Details of a Researcher - ISHIGAMI Genya

Papers - ISHIGAMI Genya

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Design and Development of Jamming-based Stiffness-Adjustable Wheel on Soft Terrain

Suthisomboon, T., Bonardi, S., Ishigami. G.,

Journal of Terramechanics (PERGAMON-ELSEVIER SCIENCE LTD) 117 101014 (11pages) 2025

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted

Tangle- and Contact-free Path Planning for a Tethered Mobile Robot using Deep Reinforcement Learning

Shimada, R., and Ishigami, G.,

Frontiers in Robotics and AI (Frontiers in Robotics and AI) 11 1388634 (13 pages) 2024.09

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted

Acoustic Odometry for Wheeled Robots on Loose Sandy Terrain

Andreu Gimenez Bolinches and Genya Ishigami

Proceedings of 13th International Workshop on Robot Motion and Control (RoMoCo2024) 255-260 2024.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Parameter study and identification of DEM modeling for varied sand moisture content based on bulldozing experiment

Sato N., Ishigami G.

Journal of Terramechanics (Journal of Terramechanics) 113-114 100971 (15 pages) 2024.06

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00224898

The discrete element method (DEM) has been widely used to simulate varied sand particles interacting with earthmoving machines. However, past research using DEM barely addressed accurate verification and validation for different sand moisture content. Therefore, the main purpose of this paper is to reveal the range of key parameters of an adhesive force model used in the DEM simulation corresponding to the specific sand moisture content. We considered the bulldozing phenomenon to be typical earthmoving work and performed the bulldozing experiments under different sand moisture levels to investigate the bulldozing force variations. Subsequently, the DEM simulation with an adhesive force model calculated the bulldozing force corresponding to the experimental results. The values for two adhesive parameters, i.e., a scaling magnitude and the maximum adhesive distance between particles, were adjusted such that the maximum bulldozing force calculated in the DEM coincides with that of the experiments under different moisture contents. The experimental verification of the DEM revealed the relationship curves between these two key parameters corresponding to the different moisture content. The relationship obtained in this paper implies that the DEM simulation carefully adjusting the adhesive force parameters can reproduce machine interaction on moist sand environments accurately.

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Perception-and-Energy-aware Motion Planning for UAV using Learning-based Model under Heteroscedastic Uncertainty

Reiya Takemura and Genya Ishigami

Proceedings of the 2024 IEEE International Conference on Robotics and Automation (ICRA 2024) pp. 10103-10109 2024.05

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Accurate Rover Mobility Analysis Using HILS-DRFT with Real-Time Parameter Tuning Approach

Takahiro Fuke, Sora Ishikawa and Genya Ishigami

Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the International Society for Terrain-Vehicle Systems 2024.01

Research paper (international conference proceedings), Joint Work, Last author, Accepted

DEM-Based Analysis and Optimization of Excavation Bucket Drum for In-Situ Resource Utilization

Tomoyasu Nakano, Takuya Omura and Genya Ishigami

Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the International Society for Terrain-Vehicle Systems 2024.01

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Collaborative Robot Systems for Lunar Landing Pad Construction

Kenji Nagaoka, Genya Ishigami, Munetaka Ueno, Keiji Nagatani

Proc. of the AROB-ISBC-SWARM 2024 pp. 985-986 2024.01

Research paper (international conference proceedings), Joint Work, Accepted

Granular Flow in Reduced Gravity: Analysis and Insights from Centrifuge Experiments at the International Space Station

Takuya Omura and Genya Ishigami

Proceedings of the 21st International and 12th Asia-Pacific Regional Conference of the International Society for Terrain-Vehicle Systems 2024.01

Research paper (international conference proceedings), Joint Work, Last author, Accepted

車輪ロボットの移動性能を可視化する可操縦性楕円体の提案

Ryo Ueda, Genya Ishigami

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 2024

Research paper (scientific journal), Joint Work, Last author, Accepted

車輪ロボットの移動性能を可視化する可操縦性楕円体の提案

Yuki Goto, Genya Ishigami

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 2024

Research paper (scientific journal), Joint Work, Last author, Accepted

Modeling of slip rate-dependent traversability for path planning of wheeled mobile robot in sandy terrain

Sakayori G., Ishigami G.

Frontiers in Robotics and AI (Frontiers in Robotics and AI) 11 1320261 (16 pages) 2024

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 2296-9144

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DEM-based Analysis for Interaction Mechanics of Tracked Vehicle on Soils Containing Water

Yanagawa Hiroki, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 42 ( 4 ) 406 - 409 2024

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 02891824

Tracked vehicles has been widely used in unstructured environments such as on uneven/deformable terrains. The mobility of the track unit consisting of interconnected metal plates is the key to enhance the safety of the vehicle. This study focuses on the track and soil interaction, particularly the wetted soil. The Distinct Element Method is applied for analyzing the interaction stress between the track and soil with varied moisture content and slip ratio. The analysis revealed that the significant stress is generated to the leading edge of the track unit and the stress distribution shifts toward the rear region of the track in moist soil.

Granular flow experiment using artificial gravity generator at International Space Station

S. Ozaki, G. Ishigami, M. Otsuki, H. Miyamoto, K. Wada, Y. Watanabe, T. Nishino, H. Kojima, K. Soda, Y. Nakao, M. Sutoh, T. Maeda, T. Kobayashi

npj Microgravity (npj Microgravity) 9 ( 1 ) 61 (13 pages) 2023.12

Research paper (scientific journal), Joint Work, Accepted

Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for space exploration. In this study, we propose an experimental approach to examine a granular flow under stable artificial gravity conditions for a long duration generated by a centrifuge at the International Space Station. We also perform a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verify that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the experimental results reveals that the mass flow rate of granular flow quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.

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Path Planning Method for Soil Investigation using Mobile Robot

Arai Kohei, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 41 ( 9 ) 813 - 816 2023.11

Research paper (scientific journal), Last author, Accepted, ISSN 02891824

A lunar landing base is a key infrastructure for mass transportation from Earth to the Moon and for sustainable activities on the Moon in the future. Unmanned robots are expected to survey the soil stiffness of multiple points for securely constructing the landing infrastructure. There is a trade-off between the time or energy required for the survey, the number of survey points, and the completeness of the survey. This paper proposes a path planning for robotic soil investigation that determines the location and the number of additional survey points. The proposed method aims to obtain completeness of information related to the soil stiffness as well as to reduce the survey time. The simulation study reveals that the method achieves obtaining a certain level of completeness while it reduces the time required for the survey.

Experimental analysis on jumping mechanism using snap-through buckling of an elastic strip

Shuhei Shimizu, Takara Abe, Tomohiko G. Sano, Genya Ishigami

IUTAM Symposium on Nonlinear dynamics for design of mechanical systems across different length/time scales PS08, (2 pages) 2023.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

UV laser etching process: enhancing bending performance in ionic polymer-metal composites (IPMC)

N. Furusawa, K. Soda, N. Matsuhisa, G. Ishigami, J. Ogawa, M. Asai and H. Takahashi

Proc. of the 14th Japan-China-Korea Joint Conference on MEMS/NEMS 2023 2023-P-022 (2 pages) 2023.09

Research paper (international conference proceedings), Joint Work

Jumping mechanism of elastic shells on rigid or granular substrates

Takara Abe, Shuhei Shimizu, Genya Ishigami, Tomohiko G. Sano

IUTAM Symposium on Nonlinear dynamics for design of mechanical systems across different length/time scales PS07, (2 pages) 2023.09

Research paper (international conference proceedings), Joint Work, Accepted

Path Planning with Cable-obstacles Avoidance for a Tethered Mobile Robot in Unstructured Environments

Ryuki Shimada and Genya Ishigami

Proceedings of the 34th International Symposium on Space Technology and Science (ISTS 2023) 2023-k-04, (8 pages) 2023.08

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Energy-and-perception-aware planning and navigation framework for unmanned aerial vehicles

Takemura R., Aoki N., Ishigami G.

Advances in Mechanical Engineering (Advances in Mechanical Engineering) 15 ( 4 ) 1 - 17 2023.04

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 16878132

This paper presents an energy and perception aware framework for path planning and navigation of unmanned aerial vehicles (UAVs) in GNSS-denied and spatiotemporal wind environments. The proposed framework mainly consists of the global and local path planning methods that respectively consider the energy consumption of an UAV and perception quality of a light detection and ranging (LiDAR) sensor mounted on the UAV. The energy consumption is estimated based on the aerodynamic model that calculates drag and lift forces on the UAV. The global planner then uses the total energy consumption in the spatiotemporal wind as the cost function to find an energy-efficient path as a set of waypoints. The local path planning navigates the UAV between the waypoints with maintaining the perception quality. The perception quality is quantified based on how well the LiDAR sensor scans feature points around the UAV that highly correlates with the navigation accuracy. Numerical simulation study for each of the global and local path planners validates their usefulness. Further, the overall framework is entirely verified in a long-range flight scenario of the photorealistic environments developed in the Gazebo simulation.

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Hardware-in-the-loop Simulation for Real-time Autonomous Tracking and Landing of an Unmanned Aerial Vehicle

Aoki N., Ishigami G.

2023 IEEE/SICE International Symposium on System Integration, SII 2023 (2023 IEEE/SICE International Symposium on System Integration, SII 2023) 2023

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 2474-2317

Collaborative exploration using unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) has become increasingly popular in the past decade. This study addresses real-time autonomous tracking and landing of a UAV on a moving ground vehicle, which is fundamental for the UAV-UGV collaborative exploration. The method proposed in this study estimates the relative pose and velocity between a UAV and UGV, and uses model predictive control for UAV trajectory planning while considering the field of view of the camera onboard the UAV. We elaborate the hardware-in-the-loop simulator (HITL) with a physical companion computer, and confirm that the proposed method enables a UAV to land on a UGV traversing on rough terrain based on online computations in the HITL. Additionally, we present statistical analysis of the simulation results of typical and computationally demanding scenarios to elucidate the computational cost on the real machine.

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Autonomous tracking and landing of an unmanned aerial vehicle on a ground vehicle in rough terrain

Aoki N., Ishigami G.

Advanced Robotics (Advanced Robotics) 37 ( 5 ) 344 - 355 2023

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 01691864

Collaborative exploration using unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) has become increasingly popular in academia over the past decade. This study addresses the task of autonomously landing a UAV on a ground vehicle in rough terrain, which is fundamental, yet challenging, for UAV-UGV collaborative exploration. The method proposed in this paper estimates the relative pose and velocity between UAV and UGV and uses model predictive control for UAV trajectory planning while considering the field of view of camera onboard the UAV. Through a simulation study, we confirmed that the proposed method enables a UAV to accurately track the UGV traversing in rough terrain, and to land on it with 100% success rate at the UGV velocity of 1.0 m/s and still 50% at 3.0 m/s.

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LSTM-based Prediction of Excavating Resistive Force Using Bucket Trajectory Shape

Hashizume Kosuke, Aizawa Masanori, Ooi Takeshi, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 41 ( 1 ) 102 - 105 2023

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 02891824

Unmanned construction machine has become a promising technology in the civil engineering field. The machine is still less efficient, especially in excavating soil, than the manned construction because the unmanned machine works carefully to avoid potential hazards due to unpredicted soil deformation as well as excavation force. This research aims to predict time-series resistive force of bucket during soil excavation based on the Recurrent Neural Network. First, we experimentally obtain excavating resistive force for various excavation trajectories. In the experiment, a bucket follows pre-determined trajectories with four different elliptical arcs, and the resistive force acting on the bucket is measured. The prediction model of the resistive force is then elaborated by indexing the bucket trajectories. The model validation confirms that the aspect ratio of the ellipse of the trajectories is an effective index for accurately predicting the excavating resistive force.

Uncertainty-Aware Trajectory Planning: Using Uncertainty Quantification and Propagation in Traversability Prediction of Planetary Rovers

Reiya Takemura, Genya Ishigami

IEEE Robotics & Automation Magazine (Institute of Electrical and Electronics Engineers (IEEE)) 2 - 12 2023

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 10709932

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Risk-aware Path Planning via Probabilistic Fusion of Traversability Prediction for Planetary Rovers on Heterogeneous Terrains

Endo M., Taniai T., Yonetani R., Ishigami G.

Proceedings - IEEE International Conference on Robotics and Automation (Proceedings - IEEE International Conference on Robotics and Automation) 11852 - 11858 2023

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 10504729

Machine learning (ML) plays a crucial role in assessing traversability for autonomous rover operations on deformable terrains but suffers from inevitable prediction errors. Especially for heterogeneous terrains where the geological features vary from place to place, erroneous traversability prediction can become more apparent, increasing the risk of unrecoverable rover's wheel slip and immobilization. In this work, we propose a new path planning algorithm that explicitly accounts for such erroneous prediction. The key idea is the probabilistic fusion of distinctive ML models for terrain type classification and slip prediction into a single distribution. This gives us a multimodal slip distribution accounting for heterogeneous terrains and further allows statistical risk assessment to be applied to derive risk-aware traversing costs for path planning. Extensive simulation experiments have demonstrated that the proposed method is able to generate more feasible paths on heterogeneous terrains compared to existing methods.

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Experimental Validation of Traction Control of Compaction Roller Towed by Small Mobile Robot

Sasaki Yuto, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 41 ( 8 ) 732 - 735 2023

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 02891824

Constructing lunar infrastructures including landing pad and habitable base is essential for enhancing lunar exploration and utilization in the future. The lunar surface regolith, fine-grained loose soil, needs to be compacted and consolidated enough for securely constructing the infrastructures. In this paper, we present a traction control of compaction roller towed by a small mobile robot. The control method aims to minimize the relative drawbar pull between the small mobile robot and the compaction roller. We also manufactured two different shapes of compaction rollers and verified the relationship between the roller shape and control performance. The experimental results show that the proposed traction control effectively minimizes the relative drawbar pull for the spiral-shaped roller while it becomes unstable for the cylindrical-shaped roller because of the roller excites soil bulldozing or excavation during its rolling.

Computationally efficient and sub-optimal trajectory planning framework based on trajectory-quality growth rate analysis

Takemura R., Ishigami G.

Frontiers in Robotics and AI (Frontiers in Robotics and AI) 9 994437 (15 pages) 2022.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 2296-9144

A planetary exploration rover has been used for scientific missions or as a precursor for a future manned mission. The rover’s autonomous system is managed by a space-qualified, radiation-hardened onboard computer; hence, the processing performance for such a computer is strictly limited, owing to the limitation to power supply. Generally, a computationally efficient algorithm in the autonomous system is favorable. This study, therefore, presents a computationally efficient and sub-optimal trajectory planning framework for the rover. The framework exploits an incremental search algorithm, which can generate more optimal solutions as the number of iterations increases. Such an incremental search is subjected to the trade-off between trajectory optimality and computational burden. Therefore, we introduce the trajectory-quality growth rate (TQGR) to statistically analyze the relationship between trajectory optimality and computational cost. This analysis is conducted in several types of terrain, and the planning stop criterion is estimated. Furthermore, the relation between terrain features and the stop criterion is modeled offline by a machine learning technique. Then, using the criterion predicted by the model, the proposed framework appropriately interrupts the incremental search in online motion planning, resulting in a sub-optimal trajectory with less computational burden. Trajectory planning simulation in various real terrain data validates that the proposed framework can, on average, reduce the computational cost by 47.6% while maintaining 63.8% of trajectory optimality. Furthermore, the simulation result shows the proposed framework still performs well even though the planning stop criterion is not adequately predicted.

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Active Traversability Learning via Risk-Aware Information Gathering for Planetary Exploration Rovers

Endo M., Ishigami G.

IEEE Robotics and Automation Letters (IEEE Robotics and Automation Letters) 7 ( 4 ) 11855 - 11862 2022.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 2377-3766

Traversability prediction enables safe and efficient autonomous rover operation on deformable planetary surfaces. Revealing spatial distribution from terrain geometry to rover slip behavior is key to assessing prospective traversability, but is hindered by insufficient in situ measurements on hazardous states due to conservative rover traverses. To achieve a more accurate prediction, this letter proposes a framework that actively learns latent traversability by exploring informative terrain under the constraints of stochastic rover slip. With a Gaussian process (GP) modeling the spatial distribution, we devise an iterative two-stage framework that gradually refines the model estimation, combining risk-aware informative path planning and GP updates by taking in situ measurements. The path planning stage employs our designed sampling-based algorithm to generate informative trajectories with fault-tolerant risk inference, while the GP is cautiously updated with traverse data to avoid rover immobilization. Chance constraint formulation is exploited in the framework to infer the stochastic reachability of informative regions. Through GP estimates reducing uncertainty, the algorithm incrementally reaches informative yet hazardous states along feasible trajectories. Simulation studies in rough terrain environments demonstrate that the proposed framework gathers informative traverse data while averting rover stuck situations to estimate the latent traversability model.

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Active Traversability Learning via Risk-aware Information Gathering for Planetary Exploration Rovers

Masafumi Endo and Genya Ishigami

Proceedings of 2022 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2022) pp. 11855-11862 2022.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Human-Following Control in Furrow For Agricultural Support Robot

Yorozu A., Ishigami G., Takahashi M.

Proceedings of the 16th International Conference on Intelligent Autonomous Systems (Lecture Notes in Networks and Systems) 2022

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 23673370

In Japan, the reduction in agricultural work population and increase in abandoned cultivated land are major social issues. To overcome these issues, we have proposed a small agricultural robot that supports the transportation of harvested crops while it follows the user. To move in the furrowed field, ridges and furrows where the robot can move must be detected using robot-mounted sensors and follow the ridge while avoiding the ridges and crop rows. However, when the robot follows the user ahead of it, it has difficulty detecting the ridges because of occlusion by the user. In addition, the robot requires to follow the user and move in and out of furrows of different widths in the farm field. To achieve smooth and safe harvesting support in the field with different width furrows, we propose a method for ridge detection and tracking by measuring the furrow width and interpolation using an RGB-D camera and a method for human-following control while avoiding ridges according to the ridge observation state using fuzzy set theory. To verify the proposed methods, experiments in the farm are carried out.

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Energy-Efficient Path Planning for UAV Using Spatiotemporal Wind Model

Aoki Nobuaki, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 40 ( 3 ) 255 - 258 2022

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0289-1824

Unmanned aerial vehicles (UAVs) have been deployed in various applications. The UAVs are limited in their flight duration owing to the payload, battery capacity, or wind effects. To address the issue, we propose an energy-efficient path planning method for UAVs that explicitly considers spatiotemporal wind speed. The proposed method exploits the wind-based energy consumption model as the cost function and also implements a variable-resolution grid in the graph search. The simulation study with 648 scenarios confirms the validity of the proposed method. Further, the statistical analysis of the simulation results summarizes the impact of wind and freight mass on UAV path plannings.

Development of Hardware-in-the-loop Simulator for Rough Terrain Mobile Robotand Its Application to Real-time Tuning of Wheel Dynamics Model

Ishikawa Sora, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 40 ( 6 ) 542 - 545 2022

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 02891824

Robotic mobility analysis in rough terrain is essential for mission success on robots deployed on planetary surfaces, construction, or disaster sites. A Hardware-in-the-loop Simulation (HILS) is known as an accurate and feasible method for dynamic analysis. The HILS is the hybrid approach that considers the contact dynamics of a robot in an actual environment and calculates the robot vehicle dynamics in a numerical simulation. We developed a HILS for wheeled mobile robot in loose terrain using a single wheel test bed. The HILS is verified under several traction load conditions. Further, the HILS is coupled with a wheel contact model based on the Dynamic Resistive Force Theory (DRFT). This HILS-DRFT can simultaneously simulate multiple wheels of the mobile robot. To improve the reliability of the DRFT, we implemented a real-time tuning process for the scaling factor used in the DRFT based on the wheel sinkage. The HILS-DRFT with the real-time tuning accurately reproduces the driving force of the actual vehicle.

Perception-aware Receding Horizon Path Planning for UAVs with LiDAR-based SLAM

Takemura R., Ishigami G.

IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems (IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems) 2022-September 2022

Research paper (international conference proceedings), Joint Work, Last author, Accepted

This paper presents a perception-aware path planning framework for unmanned aerial vehicles (UAVs) that explicitly considers perception quality of a light detection and ranging (LiDAR) sensor. The perception quality is quantified based on how scattered feature points are in LiDAR-based simultaneous localization and mapping, which can improve the accuracy of pose estimation of UAVs. In the planning step of a UAV, the proposed framework selects the best path based on the perception quality from a library of candidate paths generated by the rapidly-exploring random trees algorithm. Consequently, the UAV can autonomously fly to a destination in a receding horizon manner. Several simulation trials of the photorealistic environments confirm that our proposed path planner reduces pose estimation error by approximately 85 % on average as compared with a purely-reactive path planner.

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CNN-Based Terrain Classification with Moisture Content Using RGB-IR Images

Goto Tomoya, Ishigami Genya

Journal of Robotics and Mechatronics (Fuji Technology Press Ltd.) 33 ( 6 ) 1294 - 1302 2021.12

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 09153942

Unmanned mobile robots in rough terrains are a key technology for achieving smart agriculture and smart construction. The mobility performance of robots highly depends on the moisture content of soil, and past few studies have focused on terrain classification using moisture content. In this study, we demonstrate a convolutional neural network-based terrain classification method using RGB-infrared (IR) images. The method first classifies soil types and then categorizes the moisture content of the terrain. A three-step image preprocessing for RGB-IR images is also integrated into the method that is applicable to an actual environment. An experimental study of the terrain classification confirmed that the proposed method achieved an accuracy of more than 99% in classifying the soil type. Furthermore, the classification accuracy of the moisture content was approximately 69% for pumice and 100% for dark soil. The proposed method can be useful for different scenarios, such as small-scale agriculture with mobile robots, smart agriculture for monitoring the moisture content, and earthworks in small areas.

Simulation Analysis on Steering Characteristics for Vehicle Design of Manned Pressurized Lunar Rover

Naho Yashiro, Genya Ishigami

Proceedings of 20th ISTVS International and 9th Americas Regional Conference 002 (11 pages) 2021.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Spatio-temporal prediction of soil deformation in bucket excavation using machine learning

Saku Yuki, Aizawa Masanori, Ooi Takeshi, Ishigami Genya

ADVANCED ROBOTICS (Advanced Robotics) 35 ( 23 ) 1404 - 1417 2021.06

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0169-1864

This paper proposes a prediction model for three-dimensional spatio-temporal soil deformation in bucket excavation. The prediction model for soil deformation (PMSD) consists of two machine learning processes: the long short-term memory (LSTM) and convolutional autoencoder (Conv-AE). These processes use datasets obtained from an experimental apparatus for bucket excavation developed in this work. The apparatus equips multiple depth cameras that precisely capture time-series data of soil deformation in bucket excavation. The LSTM, an extension of a recurrent neural network, successively predicts three-dimensional soil deformation. The Conv-AE is incorporated to both ends of the LSTM in order to quasi-reversibly compress and reconstruct the datasets so that the computational burden of the LSTM is relaxed. Qualitative and quantitative evaluations of the PMSD confirm the feasibility of time-series prediction of three-dimensional soil deformation. The Conv-AE shows sufficient accuracy equivalent to the measurement accuracy of the depth camera. The prediction accuracy of the PMSD is about 10 mm in most of the cases.

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Visualization and analysis of wheel camber angle effect for slope traversability using an in-wheel camera

Matsumura R, Ishigami G

Journal of Terramechanics (Journal of Terramechanics) 93 1 - 10 2021.02

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00224898

This paper visualizes and analyzes an effect of a wheel camber angle for the slope traversability in sandy terrain. An in-wheel camera developed in this work captures the wheel-soil contact phenomenon generated beneath the wheel through a transparent section of the wheel surface. The images taken by the camera are then analyzed using the particle image velocimetry. The soil flows with various wheel camber angles are analyzed with regard to the soil failure observed on the slope surface. The analysis reveals that the slope failure and soil accumulation in front of the wheel significantly affect the wheel forces and distributions of the wheel sinkage in the wheel width direction. Further, the side force of the wheel in traversing a slope decreases as the slip ratio increases because the shear stress in the slope downward direction decreases owing to the slope failure.

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Experimental study on wheel-soil interaction mechanics using in-wheel sensor and particle image velocimetry Part I: Analysis and modeling of normal stress of lightweight wheeled vehicles

Tsubaki H, Ishigami G

Journal of Terramechanics (Journal of Terramechanics) 93 23 - 39 2021.02

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00224898

This study aims to develop a wheel-soil interaction model for a lightweight wheeled vehicle by measuring the normal stress distribution beneath the wheel. The main contribution of this work is to clarify the wheel-soil interaction using a wheel testbed that equips multiple sensory systems. An in-wheel sensor accurately measures the normal stress distribution as well as the contact angles of the wheel. Particle image velocimetry with a standard off-the-shelf camera analyzes soil flow beneath the wheel. The proposed model for the normal stress distribution is formulated based on these experimental data and takes into account the following phenomena for the lightweight vehicles that have not been considered in the classical model: (1) the normal stress distribution takes the form of a Gaussian curve; (2) the normal stress distribution concentrates in the front region of the wheel contact patch; (3) the distribution is divided into two areas with the boundary determined by the maximum normal stress angle; and (4) the maximum normal stress exponentially decreases as the slip ratio increases. Then, the proposed model is experimentally validated. Furthermore, a simulation study for the wheel driving characteristics using the proposed model confirms the accuracy of the proposed model.

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Spatio-Temporal Prediction of Soil Deformation using Machine Learning

Saku Yuki, Aizawa Masanori, Ooi Takeshi, Ishigami Genya

Journal of the Robotics Society of Japan (The Robotics Society of Japan) 39 ( 4 ) 367 - 370 2021

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0289-1824

Unmanned construction machine working in dangerous environments such as construction sites and disaster areas has been developed. However, it is still necessary to improve its work efficiency especially during bulldozing and excavating soil. This research aims to develop a method for predicting soil deformation using machine learning. The feasibility of the proposed method is verified in a scenario where a simple bulldozing blade excavates soil. In the experiment, soil deformation at a front part of the blade is captured by multiple stereoscopic cameras. The camera provides depth data that are then converted to height field data. This dataset is fed to machine learning using Recurrent Neural Network (RNN) because soil deformation is continuous phenomena depending on time variation. The learned model for predicting soil deformation is confirmed in varied intrusion depth of the bulldozing blade.

Energy-aware trajectory planning for planetary rovers

Sakayori G, Ishigami G

Advanced Robotics (Advanced Robotics) 35 ( 21-22 ) 1302 - 1316 2021

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 01691864

Planetary rovers are becoming indispensable for exploration activities and science missions. The rover used in such mission is often limited in its operation time owing to power and computational resources of the rover. In this paper, a trajectory planning method for a planetary rover is proposed that considers vehicle dynamics, and energy management of the rover. The vehicle dynamics is approximated from a dynamic simulation of the rover, which can estimate the power consumption in accordance with terrain traversability of the rover. The power generation of the solar array panel mounted on the rover is also taken into account. The simulation study confirmed the usefulness of the proposed method, especially in scenarios where slopes could be observed, and one result indicated that the energy margin could be improved by 4.1 kJ, 13.9 (Formula presented.) at maximum.

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Wide-range routing method for lunar exploration rovers using multi-objective optimization

Nakanishi R., Ishigami G.

Advanced Robotics (Advanced Robotics) 35 ( 21-22 ) 1317 - 1331 2021

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 01691864

This paper presents a wide-range routing method for multiple rovers deployed for a lunar polar exploration mission. In the mission scenario considered in this paper, multiple exploration points are divided into several sets of points to be assigned to multiple rovers. Subsequently, routes between the exploration points are generated for each rover. This assignment and routing problems are well known as the multiple Traveling Salesman Problem (mTSP). The scenario aims to minimize two objective functions: the sum and standard deviation of operation time among the multiple rovers. This problem is then subject to the multi-objective mTSP (MOmTSP). Therefore, the proposed method is composed of a three-step procedure for solving the MOmTSP. First, the k-means algorithm divides an exploration area into several regions for the number of rovers. Subsequently, a routing algorithm with the space-filling curve and 2-opt algorithm determines the order of exploration points in each region. A local path planner then generates a feasible path between two exploration points. The simulation results using the proposed method with 80 cases are statistically analyzed. We confirm that the proposed method solves the multiple optimization problems by finding the routes that can equalize the rover's operation time and minimize their deviations.

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Traversability-based Trajectory Planning with Quasi-Dynamic Vehicle Model in Loose Soil

Takemura R., Ishigami G.

Proceedings of the 2021 IEEE International Conference on Intelligent Robots and Systems (IEEE International Conference on Intelligent Robots and Systems) 8411 - 8417 2021

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 21530858

This paper presents a framework for trajectory planning that explicitly considers robotic traversability based on a quasi-dynamic vehicle model of a mobile robot in loose soil. The quasi-dynamic model estimates the slip effect due to wheel-terrain interaction forces regardless of solving complicated multibody dynamics. Therefore, our proposed model is computationally efficient for quantifying how the robot safely traverses each trajectory segment generated by a planning algorithm. The trajectory planning in our framework exploits a sampling-based incremental search algorithm, i.e., Closed-Loop Rapidly-Exploring Random Trees (CL-RRT). In the tree extension process of the CL-RRT, the traversability assessment based on the quasi-dynamic vehicle model excludes the trajectory segment associated with a hazardous wheel slip ratio. As a result, a trajectory generated from the proposed framework is safely traversable for the robot even in high slip terrain. Simulation results show that the proposed vehicle model can run 57K times faster than the dynamic model and predict the robot motion 3 times more accurately than the kinematic model. Multiple trials of the trajectory planning simulation show that our proposed framework incorporated with the quasi-dynamic model reduces a wheel slip ratio by about 40 % as compared with the kinematic model.

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TOWARDS MODIFIED DYNAMIC RESISTIVE FORCE THEORY FOR A FAST-ROTATING WHEEL ON LOOSE SAND

Tanabe Y., Ishigami G.

Proceedings of the 20th International and 9th Americas Conference of the International Society for Terrain-Vehicle Systems, ISTVS 2021 (Proceedings of the 20th International and 9th Americas Conference of the International Society for Terrain-Vehicle Systems, ISTVS 2021) 2021

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Newly proposed missions to the Moon/Mars often require vehicles to operate at high speed for time-efficient surface explorations. Among wheel-terrain interaction models in the past being applicable for quasi-static locomotion, a granular Resistive Force Theory (RFT) is increasingly employed alternatively for its simplicity and applicability. The RFT has also been extended to the Dynamic RFT (DRFT), which considers the rate-dependent effects often seen in the high-speed locomotion. In this research, first, we validate the DRFT through single-wheel experiments. The results suggest that the original DRFT underestimates the influence of wheel rut and that the granular flow beneath the wheel may decrease the wheel traction force. We then propose an empirically modified DRFT (m-DRFT), which considers an appropriate evaluation of the wheel rut depth and a simplified model for the granular flow. The comparison with the experimental results confirms that the m-DRFT accurately predicts the wheel drawbar pull in relatively low slip conditions while the original DRFT overestimates it. Moreover, the m-DRFT reproduces the temporal oscillations of the drawbar pull generated by the wheel grousers. These results imply that the m-DRFT is applicable for transient locomotion state or even fast-rotating wheel where estimating the sequential changes of wheel forces becomes essential.

TOWARDS HIGH-FIDELITY ANALYSIS ON WHEELED MOBILE ROBOT ON SOFT TERRAIN USING HARDWARE-IN-THE-LOOP SIMULATOR

Ishikawa S., Ishigami G.

Research paper (international conference proceedings), Joint Work, Last author, Accepted

This paper introduces a Hardware-In-the-Loop Simulation (HILS) framework for a wheeled mobile robot traveling on sandy terrain. The HILS is a hybrid method that incorporates an experimental approach into a numerical simulation. The HILS in our work employs a single-wheel testbed for the experimental setup where the traction force of the wheel on soft soil under various slip conditions is measured. The dynamics of the robot vehicle in response to the wheel traction force is calculated by a simple dynamics model based on Newton’s equation of motion. A key technique of the HILS developed in this work is the damping coefficient implemented in the dynamics model. To verify the fidelity and stability of the HILS, wheel driving tests with the HILS are conducted in the following process: first, a wheel driving data (wheel translational velocity, wheel traction force, and wheel slip) with various input parameters (damping coefficient and wheel angular velocity) is experimentally measured only using the wheel testbed. Subsequently, another wheel driving data is measured while the HILS calculates the dynamic response of the wheel in accordance with the corresponding external forces. The validity of the HILS is compared based on the difference between the actual and calculated wheel driving data. In this process, the value of the damping coefficient is determined such that the dynamic response well matches with the actual driving data. Furthermore, wheel driving data with external disturbances to the wheel is experimentally simulated using the HILS.

EXPERIMENTAL MEASUREMENT OF SOIL-TRACK CONTACT STRESS IN STEERING MOTION ON LOOSE SAND

Shomura T., Ishibashi S., Ishigami G.

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Modeling the dynamic interaction of construction machines on loose terrain is essential for accurately predicting the vehicle's motion and for reliably conducting its operation. The track system is often exploited as the mobility for the construction machine the track shows high trafficability on loose terrain. Track-terrain interaction mechanics has been well investigated in the past, while that in steering motion of the track remains an open issue. Therefore, this research aims to clarify the interaction mechanics of the steering track on loose sand using the following experimental apparatus: an in-track sensor and a track-steering testbed. The in-track sensor possesses multiple small three-axis sensors on the track shoes. Each track shoe has multiple holes for the sensor such that the sensing position is selectable along with the track direction. This in-track sensor can measure the contact stress distribution generated between the track and loose sand. The steering testbed emulates a pivot turning of a tracked vehicle by offsetting the track at an arbitrary distance from the center of rotation of the steering testbed. The experiments using these two apparatuses reveal that the shear stress beneath the track shows a different tendency in its steering motion: the maximum shear stress of the towed track is generated at the center of the contact region while that of the driving track is at the front region. These observations can contribute to a better understanding of the steering motion of a construction machine on loose terrain.

特集「古今未曽有の日本の月/火星地下世界探査 (UZUME)計画」小型探査プローブ搭載の複数広角カメラを用いた縦孔側壁の3次元再構成特集「古今未曽有の日本の月/火星地下世界探査 (UZUME)計画」小型探査プローブ搭載の複数広角カメラを用いた縦孔側壁の3次元再構成

Enokida N., Miyauchi T., Ishigami G.

Planetary People - The Japanese Society for Planetary Sciences (The Japanese Society for Planetary Sciences) 29 ( 4 ) 208 2020.12

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0918-273X

（要旨） 本論文では，月縦孔降下中の探査プローブが撮像した複数の時系列画像を用いて，月縦孔側壁形状を3次元再構成することを目的とする．3次元再構成では，Simultaneous Localization and Mapping (SLAM) の技術を援用し，探査プローブの自由落下運動条件をSLAM の各処理過程に組み込むことによって，カメラの回転に頑強なSLAM へと改良した．提案SLAM のシミュレーション検証において，3次元再構成の精度向上を確認した．さらに，探査プローブ搭載カメラの性能の違いによる3次元再構成への影響の検証も実施し，本研究で得られた検証結果から，ミッションシナリオと探査プローブの運動要件，カメラ性能に関する議論を行った．

Experimental study on wheel-soil interaction mechanics using in-wheel sensor and particle image velocimetry part II. Analysis and modeling of shear stress of lightweight wheeled vehicle

Horiko S, Ishigami G

Journal of Terramechanics (Journal of Terramechanics) 91 243 - 256 2020.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00224898

Wheeled vehicle mobility on loose sand is highly subject to shear deformation of sand around the wheel because the shear stress generates traction force of the wheel. The main contribution of this paper is to improve a shear stress model for a lightweight wheeled vehicle on dry sand. This work exploits two experimental approaches, an in-wheel sensor and a particle image velocimetry that precisely measure the shear stress and shear deformation generated at the interaction boundary. Further, the paper improves a shear stress model. The model proposed in this paper considers a force chain generated inside the granular media, boundary friction between the wheel surface and sand, and velocity dependency of the friction. The proposed model is experimentally validated, and its usefulness is confirmed through numerical simulation of the wheel traction force. The simulation result confirmed that the proposed model calculated the traction force with an accuracy about 70%, whereas the conventional one overestimated the force, and its accuracy was 13% at the best.

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Vision-based measurement of spatio-temporal deformation of excavated soil for the estimation of bucket resistive force

Tsuchiya K, Ishigami G

Journal of Terramechanics (Journal of Terramechanics) 90 11 - 21 2020

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 00224898

© 2020 ISTVS This paper reports a vision-based technique of measuring the spatio-temporal deformation of excavated soil for estimating the bucket resistive force. The proposed measurement technique uses two depth cameras to determine three-dimensional soil-surface displacement. The technique consists of the following two processes: the first is related to image correlation between the two cameras, and the second involves data filtering and smoothing for generating soil deformation as a continuously curved surface. The proposed technique delivers measurement accuracy to the nearest centimeter. Typical experimental results of the three-dimensional measurement of soil deformation using the proposed technique are presented in the paper. Further, this study updates an interaction model for the resistive-force estimation while a bucket excavates soil. The model introduces a correction variable that changes with the bucket wrist angle by exploiting the experimental measurement of soil deformation. The model estimates the resistive force with an error of less than one quarter of the maximum force. These updates also exhibit the effectiveness of the proposed technique.

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Resistive Force Estimation for Bucket Excavation Using Machine Learning

Kenji Tsuchiya Genya Ishigami

Proceedings of the 15th Europian-African Regional Conference of the International Society of Terrain Vehicle Systems (ISTVS2019) 9 pages 2019.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Slip Estimation Using Machine Learning of Wheel Trace Patterns for Mobile Robot on Loose Soil

Yuki Saku, Genya Ishigami

Proceedings of the 15th Europian-African Regional Conference of the International Society of Terrain Vehicle Systems (ISTVS2019) 9 pages 2019.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Ridge-tracking for Strawberry Harvesting Support Robot According to Farmer's Behavior

Ayanori Yorozu, Genya Ishigami, Masaki Takahashi

Proceedings of the 12th Conference on Field and Service Robotics (FSR2019) #32 (11 pages) 2019.08

Research paper (international conference proceedings), Joint Work, Accepted

Current Status of UZUME Mission

Junichi Haruyama, Isao Kawano, Toshihiko Nishibori, Takahiro Iwata, Yukio Yamamoto, Masato Sakurai, Masatsugu Otsuki, Genya Ishigami

Proceedings of the 32nd International Symposium on Space Technology and Science (ISTS 2019) k-06 (6 pages) 2019.06

Research paper (international conference proceedings), Joint Work, Accepted

Dynamic Simulation of Sky Crane Landing System for Mars Exploration Rover

Kotaro Hirota, Genya Ishigami

Proceedings of the 32nd International Symposium on Space Technology and Science (ISTS 2019) k-55 (5 pages) 2019.06

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Routing Method for Wide-Range Exploration of Multiple Rovers in Rough Terrain

Reina Nakanishi, Genya Ishigami

Proceedings of the 32nd International Symposium on Space Technology and Science (ISTS 2019) k-09 (6 pages) 2019.06

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Routing Problem of Multiple Mobile Robots with Human Workers for Pickup and Dispatch Tasks in Warehouse

Ono Y, Ishigami G

Proceedings of the 2019 IEEE/SICE International Symposium on System Integration, SII 2019 (Proceedings of the 2019 IEEE/SICE International Symposium on System Integration, SII 2019) 176 - 181 2019.04

Research paper (international conference proceedings), Joint Work, Last author, Accepted

© 2019 IEEE. This paper presents a routing problem of multiple mobile robots collaborating with human workers in a ware-house. In a scenario considered in this paper, the warehouse stores several different of heavy items on multiple stock locations. The human worker pick items up from corresponding stock location, puts them on one of the mobile robot carriers, and then visits another stock location. The multiple mobile robots deployed in the warehouse visit stock locations by following specified routes, carry several items for the worker, and deliver them to a dispatch area in the warehouse. Here, an appropriate number of robots, the maximum speed of each robot, and the load capacity of each robot should be quantitatively analyzed while the routing problem of the multiple robots with the human worker in the warehouse is considered. The research in this paper develops a simulation framework in which the worker and the robots cooperatively performs the pickup and dispatch tasks. An algorithm of the routing problem in the framework is addressed based on the Mixed-integer linear programming, which calculates the order of the picking points for each robot. Simulation studies for an actual warehouse are performed with different conditions between the number of robots, speed, and load capacity. The simulation framework calculates a task time which indicates how long the robots and worker need to complete one shipping list. The task time also quantitatively indicate how large the multiple robots reduce the work load of the human worker.

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Simulator for disaster response robotics

Kanehiro F., Nakaoka S., Sugihara T., Wakisaka N., Ishigami G., Ozaki S., Tadokoro S.

Springer Tracts in Advanced Robotics (Springer Tracts in Advanced Robotics) 128 453 - 477 2019

Research paper (scientific journal), Joint Work, Accepted, ISSN 16107438

© Springer Nature Switzerland AG 2019. This chapter presents a simulator for disaster response robots based on the Choreonoid framework. Two physics engines and a graphics engine were developed and integrated into the framework. One physics engine enables robust contact-force computation among rigid bodies based on volumetric intersection and a relaxed constraint, whereas the other enables accurate and computationally efficient computation of machine–terrain interaction mechanics based on macro and microscopic approaches. The graphics engine allows simulating natural phenomena, such as rain, fire, and smoke, based on a particle system to resemble tough scenarios at disaster sites. In addition, wide-angle vision sensors, such as omnidirectional cameras and LIDAR sensors, can be simulated using multiple rendering screens. Overall, the simulator provides a tool for the efficient and safe development of disaster response robots.

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Dual-arm construction robot with remote-control function

Yoshinada H., Kurashiki K., Kondo D., Nagatani K., Kiribayashi S., Fuchida M., Tanaka M., Yamashita A., Asama H., Shibata T., Okutomi M., Sasaki Y., Yokokohji Y., Konyo M., Nagano H., Kanehiro F., Sugihara T., Ishigami G., Ozaki S., Suzumori K., Ide T., Yamamoto A., Hioki K., Oomichi T., Ashizawa S., Tadakuma K., Takamori T., Kimura T., Murphy R., Tadokoro S.

Springer Tracts in Advanced Robotics (Springer Tracts in Advanced Robotics) 128 195 - 264 2019

Research paper (scientific journal), Joint Work, Accepted, ISSN 16107438

© Springer Nature Switzerland AG 2019. In disaster areas, operating heavy construction equipment remotely and autonomously is necessary, but conventional remote-controlled heavy equipment has problems such as insufficient operability, limited mobility on slopes and stairs, and low work efficiency because of difficult remote control. As part of the ImPACT-TRC Program, a group of Japanese researchers attempts to solve these problems by developing a construction robot for disaster relief tasks with a new mechanism and new control methods. This chapter presents the overview of construction robot and the details of main elemental technologies making up the robot. Section 5.1 describes the basic configuration of the robot and the teleoperation system. Section 5.2 is a tether powered drone which provides extra visual information. Sections 5.4 and 5.3 are force and tactile feedback for skillful teleoperation. Section 5.5 is visual information feedback which consists of an arbitrary viewpoint visualization system and a visible and LWIR camera system to observe surrounding of the robot in a dark night scene and/or a very foggy scene. These functions can dramatically increase construction eq

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Development of In-track Sensor System for Three Dimensional Measurement of Pressure Distribution on Loose Soil

Satoshi Ishibashi, Genya Ishigami

Proceedings of the Joint 10th Asia-Pacific Conference of the International Society for Terrain-Vehicle Systems 1-2 (11 pages) 2018.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Experimental Analysis of Bucket-soil Interaction Mechanics using Sensor-embedded Bucket Test Apparatus

Kenji Tsuchiya, Genya Ishigami

Proceedings of the Joint 10th Asia-Pacific Conference of the International Society for Terrain-Vehicle Systems 8-4 (11 pages) 2018.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Experimental Analysis of Camber Angle Effect on Slope Traversability of Wheeled Mobile Robot

Ryota Matsumura, Genya Ishigami

Proceedings of the Joint 10th Asia-Pacific Conference of the International Society for Terrain-Vehicle Systems 5-1 (8 pages) 2018.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Experimental Analysis on Landing Dynamics of Martian Moon Spacecraft based on Similarity Law

Daiki Yamaguchi, Genya Ishigami

Proceedings of the 14th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2018) 3a-4 (8 pages) 2018.06

Research paper (international conference proceedings), Joint Work, Last author

Strategic Deployment and Rerouting Methods for Wide-range Surface Exploration using Multiple Rovers

Reina Nakanishi, Genya Ishigami

Proceedings of the 14th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2018) 6c-a (5 pages) 2018.06

Research paper (international conference proceedings), Joint Work, Last author

Simulation Study on Landing Behavior of Spacecraft in Microgravity Environment based on Multibody Dynamics Model

Haruhi Katsumata, Genya Ishigami

Proceedings of the 14th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2018) 3a-3 (7 pages) 2018.06

Research paper (international conference proceedings), Joint Work, Last author

Computationally Efficient Mapping for a Mobile Robot with a Downsampling Method for the Iterative Closest Point

Deguchi Shodai, Ishigami Genya

Journal of Robotics and Mechatronics (Journal of Robotics and Mechatronics) 29 ( 6 ) 65 - 75 2018.02

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 09153942

© 2018, Fuji Technology Press. All rights reserved. This paper proposes a computationally efficient method for generating a three-dimensional environment map and estimating robot position. The proposed method assumes that a laser range finder mounted on a mobile robot can be used to provide a set of point cloud data of an environment around the mobile robot. The proposed method then extracts typical feature points from the point cloud data using an intensity image taken by the laser range finder. Subsequently, feature points extracted from two or more different sets of point cloud data are correlated by the iterative closest point algorithm that matches the points between the sets, creating a large map of the environment as well as estimating robot location in the map. The proposed method maintains an accuracy of the mapping while reducing the computational cost by downsampling the points used for the iterative closest point. An experimental demonstration using a mobile robot test bed confirms the usefulness of the proposed method.

Strategy Optimization for Energy Efficient Extraterrestrial Drilling Using Combined Power Map

Pan, Siyi and Ishigami Genya

IEEE Robotics and Automation Letters 2 ( 4 ) 1980 - 1987 2017.10

Research paper (scientific journal), Joint Work, Last author, Accepted

Development and performance evaluation of planar travel distance sensors for mobile robots in sandy terrain

Yanagisawa Arata, Ishigami Genya

Journal of Robotics and Mechatronics (Fuji Technology Press) 29 ( 5 ) 887 - 894 2017.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0915-3942

A planar travel distance sensor (two-dimensional sen-sor) was developed for a mobile robot in sandy terrain. The sensor system uses an optical flow device integrated into a small module with a simple configuration. The system achieves a high sampling rate on the order of milliseconds as well as precise measurement on a sub-millimeter order. Its performance was evaluated experimentally for measurement accuracy and repeatability, velocity response, robustness at varied heights with respect to terrain, and terrain surface characteristics. The experimental results confirm that the two-dimensional sensor system is accurate, having an error of distance traveled of less than a few percent, and that it possesses a wide dynamic range for the robot’s traveling velocity. This paper also discusses the applicability of the two-dimensional sensor for practical scenarios on the basis of the experimental findings.

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Traversability-based RRT∗ for planetary rover path planning in rough terrain with LIDAR point cloud data

Takemura Reiya, Ishigami Genya

Journal of Robotics and Mechatronics (Fuji Technology Press) 29 ( 5 ) 838 - 846 2017.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0915-3942

Sampling-based search algorithms such as Rapidly-Exploring Random Trees (RRT) have been utilized for mobile robot path planning and motion planning in high dimensional continuous spaces. This paper presents a path planning method for a planetary exploration rover in rough terrain. The proposed method exploits the framework of a sampling-based search, the optimal RRT (RRT∗) algorithm. The terrain geometry used for planning is composed of point cloud data close to continuous space captured by a light detection and ranging (LIDAR) sensor. During the path planning phase, the proposed RRT∗ algorithm directly samples a point (node) from the LI-DAR point cloud data. The path planner then considers the rough terrain traversability of the rover during the tree expansion process of RRT∗. This process improves conventional RRT∗ in that the generated path is safe and feasible for the rover in rough terrain. In this paper, simulation study on the proposed path planning algorithm in various real terrain data confirms its usefulness.

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Wheel slip classification method for mobile robot in sandy terrain using in-wheel sensor

Omura Takuya, Ishigami Genya

Journal of Robotics and Mechatronics (Fuji Technology Press) 29 ( 5 ) 902 - 910 2017.10

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0915-3942

This paper proposes a method that can estimate and classify the magnitude of wheel slippage for a mobile robot in sandy terrains. The proposed method exploits a sensor suite, called an in-wheel sensor, which measures the normal force and contact angle at the wheel-sand interaction boundary. An experimental test using the in-wheel sensor reveals that the maximum normal force and exit angle of the wheel explicitly vary with the magnitude of the wheel slippage. These characteristics are then fed into a machine learning algorithm, which classifies the wheel slippage into three categories: non-stuck wheel, quasi-stuck wheel, and stuck wheel. The usefulness of the proposed method for slip classification is experimentally evaluated using a four-wheel-drive test bed rover.

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Modeling of Bucket-soil Interaction Mechanics based on Improved Resistive Force Theory

Ryota Yoneyama, Takuya Omura, Genya Ishigami

Proceedings of the 19th International & 14th European-African Regional Conference of the International Society of Terrain Vehicle Systems SES-09-1 (12 pages) 2017.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Slip Estimation and Classification Using In-wheel Sensor for Mobile Robot in Sandy Terrain

Takuya Omura, Genya Ishigami

Proceedings of the 19th International & 14th European-African Regional Conference of the International Society of Terrain Vehicle Systems SES-09-2 (10 pages) 2017.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Automated Dust Devil Detection on Mars

Kazunori OGOHARA, Daiki YASUNAGA, Genya ISHIGAMI

Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan 14 ( ists30 ) Pk_131 - Pk_136 2017.02

Research paper (scientific journal), Joint Work, Accepted

A system for automated dust devil detection on Mars is developed based on images taken by the navigation camera aboard the Mars Exploration Rover, Spirit. This system enables us to pick up dust devils from the large number of images without checking each image visually and affords us a powerful tool for searching for dust devils and revealing their statistical properties for scientific studies. From an engineering point of view, the volume of dust devil image data to be downlinked to Earth for dust devil studies can also be drastically reduced by automated detection of dust devils because we can trim dust devil regions on the images onboard. A simple performance test using images taken on a particular sol shows that this system can detect almost all of the dust devils though also includes some false positives. Precision and recall are 0.85 and 0.81, respectively, which are comparable with or more effective than those in previous studies.

LDM (Life Detection Microscope): In situ Imaging of Living Cells on Surface of Mars

Akihiko YAMAGISHI, Takehiko SATOH, Keigo ENYA, Atsuo MIYAKAWA, Yoshitaka YOSHIMURA, Hajime HONDA, Eiichi IMAI, Satoshi SASAKI, Genya ISHIGAMI, Kazuhisa FUJITA, Hideaki MIYAMOTO

Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan (Japan Society for Aeronautical and Space Sciences) 14 ( ists30 ) Pk_117 - Pk_124 2017.02

Research paper (scientific journal), Joint Work, Accepted

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Energy Efficient Slope Traversability Planning for Mobile Robot in Loose Soil

Go Sakayori, Genya Ishigami

Proceedings of the 2017 IEEE International Conference on Mechatronics 99-104 2017.02

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Gyro-based odometry associated with steering characteristics for wheeled mobile robot in rough terrain

Nagata Takuma, Ishigami Genya

Advanced Robotics (TAYLOR & FRANCIS LTD) 30 ( 23 ) 1495 - 1508 2016.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 0169-1864

Mobile robot used for planetary exploration performs several scientific missions over long distance travel and needs to have a high degree of autonomous mobility system because the communication delay from the Earth impedes its direct teleoperation. Localization of a mobile robot is of particular importance on the autonomous mobility. Classical localization methods such as wheel/visual odometry have been widely investigated and demonstrated, but they possess a well-known trade-off between computational cost and localization accuracy. This paper proposes an accurate gyro-based odometry method for a wheeled mobile robot in rough terrain. The robot in rough terrain is often subject to large wheel slip or vehicle sideslip related with its steering maneuver, and those slips degrade the localization accuracy. The basic approach of the proposed method is to exploit odometry data for the robot distance traveled as well as gyroscope data for the robot heading calculation; however each data-set is weighted in accordance with steering characteristics of a robot in rough terrain. The usefulness of the proposed method is examined through field experiments using a wheeled mobile robot testbed in Martian analog site. The experimental result confirms that the proposed method accurately estimates the robot trajectory.

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Experimental Investigation of Stuck Wheel Characteristics in Loose Sand

Takuya Ohmura, Genya Ishigami

Proceedings of the 8th Americas Regional Conference of the International Society for Terrain-Vehicle Systems #56 (9 pages) 2016.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Power Consumption Model for Slope Traversal of Wheeled Robot based on Dynamic Simulation

Go Sakayori, Genya Ishigami

Proceedings of the 8th Americas Regional Conference of the International Society for Terrain-Vehicle Systems #79 (11 pages) 2016.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Modeling of Wheel-soil Interaction Mechanisms based on Accurate Measurement of Pressure Distribution for Lightweight Vehicle

Hiroki Tsubaki, Genya Ishigami

Proceedings of the 8th Americas Regional Conference of the International Society for Terrain-Vehicle Systems #39 (11 pages) 2016.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Experimental Evaluation of Gyro-based Odometry Focusing on Steering Characteristics of Wheeled Mobile Robot in Rough Terrain

Takuma Nagata, Genya Ishigami

Proceedings of the 13th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2016) 8b-4 2016.06

Research paper (international conference proceedings), Joint Work, Last author

Power-synchronized Path Planning for Mobile Robot in Rough Terrain

Go Sakayori, Genya Ishigami

Proceedings of the 13th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2016) 5c-4 2016.06

Research paper (international conference proceedings), Joint Work, Last author

Modeling of LiDAR Measurement Uncertainty for Rover Path Planning

Koki Tanaka, Genya Ishigami

Proceedings of the 13th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2016) 5c-2 2016.06

Research paper (international conference proceedings), Joint Work, Last author

Experimental Evaluation of Voltage Control Methods in Electrical Power System for Planetary Rover

Takahiro Akutsu, Genya Ishigami

Proceedings of the 13th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2016) 8a-4 2016.06

Research paper (international conference proceedings), Joint Work, Last author

Mission Concepts of Unprecedented Zipangu Underworld of the Moon Exploration (UZUME) Project

Junichi HARUYAMA, Isao KAWANO, Takashi KUBOTA, Masatsugu OTSUKI, Hiroki KATO, Toshihiko NISHIBORI, Takahiro IWATA, Yukio YAMAMOTO, Yoshiaki ISHIHARA, Aiko NAGAMATSU, Kazuhito SHIMADA, Toshiaki HASENAKA, Tomokatsu MOROTA, Masaki N. NISHINO, Ko HASHIZUME, Kazuto SAIKI, Motomaro SHIRA, Goro KOMATSU, Nobuyuki HASEBE, Hisayoshi SHIMIZU, Hideaki MIYAMOTO, Kensei KOBAYASHI, Shinichi YOKOBORI, Tatsuhiro MICHIKAMI, Satoru YAMAMOTO, Yasuhiro YOKOTA, Hitoshi ARISUMI, Genya ISHIGAMI, Katsushi FURUTANI, Yuichi MICHIKAWA

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (Japan Society for Aeronautical and Space Sciences) 14 ( ists30 ) Pk_147 - Pk_150 2016

Research paper (scientific journal), Joint Work, Accepted

We are planning to explore the caverns through the skylight holes on the Moon and Mars. The holes and their associated subsurface caverns are among the most important future exploration targets. The importance of the lunar and Martian holes and their associated caverns is categorized from two aspects: (1) fresh materials are easily observed and sampled there, and (2) the subsurface caverns provide a safe, quiet environment. The expectation of lunar and Martian hole and cavern exploration is increasing in Japan. We name the project as UZUME (Unprecedented Zipangu (Japan) Underworld of the Moon Exploration) whose name is after a Japanese mythology. The ultimate purpose of the UZUME project is to investigate how to expand human activity and survival in space and on extraterrestrial bodies.

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Excavation model of soil sampling device based on particle image velocimetry

Mori, Daiki, Ishigami, Genya

JOURNAL OF TERRAMECHANICS (PERGAMON-ELSEVIER SCIENCE LTD) 62 19 - 29 2015.12

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0022-4898

This work aims to establish an energy-efficient strategy for sampling Martian subsurface soil for future extraterrestrial-life exploration missions. To this end, requirements for a robotic arm are carefully examined and an end-effector shape suitable for subsurface soil sampling is determined. A soil tool interaction model is formulated based soil-flow measured by particle image velocimetry (PIV). The proposed model calculates the resistance forces and torque generated during the sampling procedure and is validated through a comparison of experimental data obtained from the force sensor and numerical data calculated from the proposed model. Results indicate that the proposed model provides an accurate estimation of the force generated during soil sampling. Furthermore, the interaction model is capable of estimating the robotic arm's energy consumption and calculating the most efficient tool size to use. (C) 2015 ISTVS. Published by Elsevier Ltd. All rights reserved.

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Development of in-wheel sensor system for accurate measurement of wheel terrain interaction characteristics

Shirai, Takayuki, Ishigami, Genya

JOURNAL OF TERRAMECHANICS (PERGAMON-ELSEVIER SCIENCE LTD) 62 51 - 61 2015.12

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 0022-4898

Planetary rovers need high mobility on a rough terrain such as sandy soil, because such a terrain often impedes the rover mobility and causes significant wheel slip. Therefore, the accurate estimation of wheel soil interaction characteristics is an important issue. Recent studies related to wheel soil interaction mechanics have revealed that the classical wheel model has not adequately addressed the actual interaction characteristics observed through experiments. This article proposes an in-wheel sensor system equipped with two sensory devices on the wheel surface: force sensors that directly measure the force distribution between the wheel and soil and light sensors that accurately detect the wheel soil surface boundary line. This sensor design enables the accurate measurement of wheel terrain interaction characteristics such as wheel force distribution, wheel soil contact angles, and wheel sinkage when the powered wheel runs on loose sand. In this article, the development of the in-wheel sensor system is introduced along with its system diagram and sensor modules. The usefulness of the in-wheel sensor system is then experimentally evaluated via a single wheel test bench. The experimental results confirm that explicit differences can be observed between the classical wheel model and practical data measured by the in-wheel sensor system. (C) 2015 ISTVS. Published by Elsevier Ltd. All rights reserved.

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Design and Development of Built-in-Clutch Joint for Single-Drive and Multi-Degrees of Freedom Manipulator

Saki Morita. Daiki Mori, and Genya Ishigami

The 6th International Conference on Advanced Mechatronics 2A1-11 2015.12

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Design, Development, and Mobility Evaluation of an Omnidirectional Mobile Robot for Rough Terrain

Ishigami, Genya, Iagnemma, Karl, Overholt, Jim, Hudas, Greg

JOURNAL OF FIELD ROBOTICS (WILEY-BLACKWELL) 32 ( 6 ) 880 - 896 2015.09

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1556-4959

Omnidirectional vehicles have been widely applied in several areas, but most of them are designed for the case of motion on flat, smooth terrain, and are not feasible for outdoor usage. This paper presents the design and development of an omnidirectional mobile robot that possesses high mobility in rough terrain. The omnidirectional robot consists of a main body with four sets of mobility modules, called an active split offset caster (ASOC). The ASOC module has independently driven dual wheels that produce arbitrary planar translational velocity, enabling the robot to achieve its omnidirectional motion. Each module is connected to the main body via a parallel link with shock absorbers, allowing the robot to conform to uneven terrain. In this paper, the design and development of the ASOC-driven omnidirectional mobile robot for rough terrain are described. A control scheme that considers the kinematics of the omnidirectional mobile robot is presented. The mobility of the robot is also evaluated experimentally based on a metric called the ASOC mobility index. The mobility evaluation test clarifies a design tradeoff between terrain adaptability and omnidirectional mobility due to the shock absorbers. In addition, an odometry improvement technique that can reduce position estimation error due to wheel slippage is proposed. Experimental odometry tests confirmed that the proposed technique is able to improve the odometry accuracy for sharp-turning maneuvers.

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Generalized Force-and-Energy Manipulability for Design and Control of Redundant Robotic Arm

Daiki Mori, Genya Ishigami

Proceedings of the 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2015) pp. 1131-1136 2015.09

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Automated Dust Devil Detection on Mars

Kazunori Ogohara, Daiki Yasunaga1, Genya Ishigami

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) k-44 2015.07

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Design and Development of Navigation/Geological Cameras for a Mars Rover

Takehiko Satoh, Hideaki Miyamoto, Takafumi Niihara, Genya Ishigami

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) k-41 2015.07

Research paper (international conference proceedings), Joint Work, Accepted

LDM (Life Detection Microscope): In situ imaging of living cells on surface of Mars

Akihiko Yamagishi, Takehiko Satoh, Keigo Enya, Atsuo Miyakawa, YoshimuraYoshitaka, Hajime Honda, Eiichi Imai, Satoshi Sasaki, Genya Ishigami, Hirohide Demura, Kazuhisa Fujita, Hideaki Miyamoto

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) k-40 2015.07

Research paper (international conference proceedings), Joint Work, Accepted

Preliminary Thermal Design of a Mars Rover Mission "MELOS"

Ryuta Hatakenaka, Kazuhisa Fujita, Taku Nonomura, Moto Takai, Hiroyuki Toyota, Takehiko Satoh, Hiroyuki Sugita, Genya Ishigami, Akihiko Yamagishi, Hideaki Miyamoto, Kazuhiro Umetani

Proceedings of the 45th International Conference on Environmental Systems ICES-2015-247 2015.07

Research paper (international conference proceedings), Joint Work

Mission Scope Definition and Preliminarily Design Study of Mars Surface Exploration Rover

Genya Ishigami, Kazuhisa Fujita, Ryuta Hatakenaka, Hiroyuki Toyota, Takehiko Sato, Moto Takai, Taku Nonomura

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) k-39 2015.07

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Mission Concepts of Unprecedented Zipangu Underworld of the Moon Exploration (UZUME) Project

Junichi Haruyama, Isao Kawano, Takashi Kubota, Masatsugu Otsuki, Hiroki Kato, Toshihiko Nishibori, Takahiro Iwata, Yukio Yamamoto, Yoshiaki Ishihara, Aiko Nagamatsu, Kazuto Shimada, Toshiaki Hasenaka, Tomokatsu Morota, Masaki N. Nishino, Ko Hashizume, Kazuto Saiki, Motomaro Shirao, Goro Komatsu, Nobuyuki Hasebe, Hisayoshi Shimizu, Hideaki Miyamoto, Kensei Kobayashi, Shinichi Yokobori, Tatsuhiro Michikami, Satoru Yamamoto, Yasuhiro. Yokota, Hitoshi Arisumi, Genya Ishigami, Katsusi Furutani, Yuichi Michikawa

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) k-29 2015.07

Research paper (international conference proceedings), Joint Work, Accepted

Japan’s Mars Rover Mission - System Design and Development Status

Kazuhisa Fujita, Genya Ishigami, Ryuta Hatakenaka, Moto Takai, Hiroyuki Toyota, Naoko Ogawa, Misuzu Haruki, Hiroshi Takeuchi, Taku Nonomura, Kazuhiko Yamada, Hiroki Takayanagi, Takashi Ozawa, Shingo Matsuyama, Akira Oyama, Akihiko Yamagishi, Shingo Kameda, Hirdy Miyamoto, Takehiko Satoh

Proceedings of the 30th International Symposium on Space Technology and Science (ISTS 2015) 2015.07

Research paper (international conference proceedings), Joint Work, Accepted

車輪走行実験による沈下過渡状態におけるせん断変形モデル有効性の評価

水上憲明, 石上玄也, 吉光徹雄, 久保田孝

日本機械学会論文集 (日本機械学会) 81 ( 825 ) 14 - 00514-14-00514 2015.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 2187-9761

Soft soils cover on planetary surfaces, so the wheels for exploration rovers easily slip. Understanding an interaction between a wheel and soft soils is important for a traction control to improve rover traversability. The interaction between the wheel and soft soils has been studied in a field of terramechanics. Since the classical terramechanics-based wheel model considers only a static state of a wheel sinkage, the wheel model is not applicable to the wheel sinkage and slip. Thus the dynamic normal stress model and shear deformation model were proposed to deal with the problems of the wheel sinkage and the slip. The dynamic normal stress model was proposed by considering the wheel sinking velocity and a variation of soil state for solving the problem of wheel sinkage. And the shear deformation model was proposed by considering the shear characteristics for solving the problem of wheel slip. The shear deformation model was formulated by the shear test. The simulation verified the validity of the dynamic normal stress model and the shear deformation model in the transient state. In this paper, a single wheel experiments was performed to evaluate the shear deformation model by comparing the simulation results and the experimental results. Then the characteristics of the wheel sinkage and slip and the effectiveness of the model were confirmed.

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Accurate Measurement of Multidirectional Interaction Mechanisms between Wheel Stress and Soil Deformation using In-wheel Sensor and PIV techniques

Hiroki Tsubaki, Takayuki Shirai, Genya Ishigami

Proceedings of the 13th European Conference of the International Society for Terrain-Vehicle Systems 97-109 2015.01

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Towards Terrain Classification Method based on Force-sinkage Characteristics measured with In-wheel Sensor System

Takayuki Shirai, Hiroki Tsubaki, and Genya Ishigami

Proceedings of the 13th European Conference of the International Society for Terrain-Vehicle Systems 282-289 2015.01

Research paper (international conference proceedings), Joint Work, Last author, Accepted

Japan's mars rover mission for edl demonstration and life search

Kazuhisa Fujita, Genya Ishigami, Takehiko Satoh, Akihiko Yamagishi, Hirdy Miyamoto

Proceedings of the International Astronautical Congress, IAC 2 1061 - 1068 2015

Research paper (international conference proceedings), Joint Work, ISSN 0074-1795

A Martian rover mission is currently entertained in Japan Aerospace Exploration Agency (JAXA) for launch in 2020s. The primary scopes of this mission are to demonstrate the entry-descent-landing and surface exploration technologies on Mars, to search for signs of live organisms, and to determine when the ocean is lost in the past Martian history. In order to cut down the mission cost and the development risk, the spacecraft is designed as a compact medium-class spacecraft whose total wet mass at Earth departure is approximately 900 kg. The spacecraft system consists of the cruise module and the atmospheric entry module which is subdivided into a forebody and an aftbody aeroshell, a landing module, and a rover, in a typical reference mission design under consideration. The current status of research and development is briefly presented as well.

Accurate Estimation of Wheel Pressure-Sinkage Traits on Sandy Terrain using In-wheel Sensor System

Takayuki Shirai, Genya Ishigami

Proceedings of the 12th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2014) 8a-2 2014.06

Research paper (international conference proceedings), Joint Work, Last author

Current Status and Prospects of Terramechanics-based Simulation Techniques for Planetary Rover Locomotion

Taizo Kobayashi, Genya Ishigami, Shingo Ozaki, Masataku Sutoh

Proceedings of the 12th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2014) 11b-3 2014.06

Research paper (international conference proceedings), Joint Work

Light-Independent Feature Detection using Intensity Data of Laser Range Finder

Kentaro Kimura, Genya Ishigami

Proceedings of the 12th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2014) 11a-3 2014.06

Research paper (international conference proceedings), Joint Work, Last author

Towards Space-hardened, Small-lightweight Laser Range Imager for Planetary Exploration Rover

Genya Ishigami, Takahide Mizuno

Proceedings of the 12th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2014) 11a-2 2014.06

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author

Soil Interaction Model of Hemispherical Sampling Device based on PIV Analysis

Daiki Mori, Genya Ishigami

Proceedings of the 12th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2014) 9a-2 2014.06

Research paper (international conference proceedings), Joint Work

Conceptual Design Study of Mars EDL System with a Compact Rover

Kazuhisa Fujita, Genya Ishigami, Naoko Ogawa, Akira Oyama, Kazuhiko Yamada, Takashi Kubota, Akihiko Yamagishi, Hirdy Miyamoto, and Takehiko Satoh

Proceedings of the AIAA Science and Technology Forum and Exposition 2014 1739890 2014.01

Research paper (international conference proceedings), Joint Work

Design, development, and mobility test of an omnidirectional mobile robot for rough Terrain

Genya Ishigami, Elvine Pineda, Jim Overholt, Greg Hudas, Karl Iagnemma

Springer Tracts in Advanced Robotics 92 599 - 611 2014

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1610-7438

Omnidirectional vehicles have been widely applied in several areas, but most of them are designed for the case of motion on flat, smooth terrain, and are not feasible for outdoor usage. This paper presents an omnidirectional mobile robot that possesses highmobility in rough terrain. The omnidirectional robot employs four sets of mobility modules, called active split offset caster (ASOC). The ASOCmodule has two independently-driven wheels that produce arbitrary planar translational velocity, enabling the robot to achieve its omnidirectional mobility. Each module is connected to the main body of the robot via a parallel link with shock absorbers. In this paper, a design and development of the ASOC-driven omnidirectional mobile robot for rough terrain are described. Also, a control scheme that considers a kinematics of the omnidirectional mobile robot is presented. The omnidirectional mobility of the robot regardless of ifs heading direction is experimentally evaluated based on ametric called omnidirectional mobility index. © Springer-Verlag Berlin Heidelberg 2014.

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Particle Filter based 3D Position Tracking for Terrain Rovers using Laser Point Clouds

Peshala G. Jayasekara, Genya Ishigami, Takashi Kubota

2014 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS 2014) (IEEE) 2369 - 2374 2014

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 2153-0858

Difficult conditions on outdoor terrains make outdoor autonomy for rovers, a challenging task. The conventional wheel odometry method uses orientation measurements to assume a momentary plane to apply wheel encoder readings. On uneven terrains, this method often gives poor results for position tracking, and therefore rarely used. To improve the conventional odometry motion model, immediate terrain data can be used. This paper proposes a novel state variable extension (SVE) method to establish a connection between state space variables of a terrain rover by combining terrain point clouds with rover kinematics. The simulation results show that when the 2D state variables (x, y, yaw) are known, the 2D state can be extended to its 3D state (x, y, z, roll, pitch, yaw) with minimal error. The proposed SVE method is employed in a particle filter to determine the 2D state variables, which in turn results in achieving the full 3D position tracking of the rover.

Path planning and navigation framework for a planetary exploration rover using a laser range finder

Genya Ishigami, Masatsugu Otsuki, Takashi Kubota

Springer Tracts in Advanced Robotics 92 431 - 447 2014

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1610-7438

This chapter presents a path planning and navigation framework for a planetary exploration rover and its experimental tests at a Lunar/Martian analog site. The framework developed in this work employs a laser range finder (LRF) for terrain feature mapping. The path planning algorithm generates a feasible path based on a cost function consisting of terrain inclination, terrain roughness, and path length. A set of navigation commands for the rover is then computed from the generated path. The rover executes those navigation commands to reach a desired goal. In this paper, a terrain mapping technique that uses a LRF is described along with an introduction to a cylindrical coordinate digital elevation map (C2DEM). The gird-based path planning algorithm is also presented. Field experiments regarding the path planning and navigation that evaluate the feasibility of the framework developed in this work are reported. © Springer-Verlag Berlin Heidelberg 2014.

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Terrain adaptive detector selection for visual odometry in natural scenes

Kyohei Otsu, Masatsugu Otsuki, Genya Ishigami, Takashi Kubota

Advanced Robotics 27 ( 18 ) 1465-1476 - 1476 2013.10

Research paper (scientific journal), Joint Work, Accepted

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Range-Dependent Terrain Mapping and Multi-path Planning using Cylindrical Coordinates for Planetary Exploration Rover

Genya Ishigami, Masatsugu Otsuki, Takashi Kubota

Journal of Field Robotics (WILEY-BLACKWELL) 30 ( 4 ) 536-551 - 551 2013.07

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1556-4959

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Case Study of Trajectory Design for Synergetic Mars Exploration by Orbiter and Lander

Naoko Ogawa, Kazuhisa Fujita, Takashi Kubota, Genya Ishigami, Akira Oyama, Kazuhiko Yamada, and Takehiko Satoh

Proceedings of the 29th International Symposium on Space Technology and Science (ISTS 2013) k-66p 2013.06

Research paper (international conference proceedings), Joint Work, Accepted

Design Study of Mars EDL Demonstrator for MELOS mission

Kazuhisa Fujita, Genya Ishigami, Naoko Ogawa, Akira Oyama, Kazuhiko Yamada, Takashi Kubota, Hirdy Miyamoto, and Takehiko Satoh

Proceedings of the 29th International Symposium on Space Technology and Science (ISTS 2013) k-11 2013.06

Research paper (international conference proceedings), Joint Work, Accepted

Feasibility Study of a Small, Lightweight Rover for Mars Surface Exploration

Genya Ishigami, Takashi Kubota, Kazuhisa Fujita, Naoko Ogawa, Takehiko Sato

Proceedings of the 29th International Symposium on Space Technology and Science (ISTS 2013) k-12 2013.06

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

MELOS Life Search Plan: Search for Microbes on the Mars Surface with Special Interest in Methane-oxidizing Bacteria

Akihiko Yamagishi, Yoshitaka Yoshimura, Hajime Honda, Aatsuo Miyakawa, Takehiko Satoh, Gennya Ishigami, Junichi Haruyama, Kensei Kobayashi, Takeshi Naganuma, Sho Sasaki, Hideaki Miyamoto

Proceedings of the 29th International Symposium on Space Technology and Science (ISTS 2013) k-13 2013.06

Research paper (international conference proceedings), Joint Work, Accepted

Preliminary Design Study of EDL System for Japan's Mars Rover Mission

Kazuhisa Fujita, Genya Ishigami, Naoko Ogawa, Akira Oyama, Kazuhiko Yamada, Takashi Kubota, Hirdy Miyamoto, and Takehiko Satoh

Proceedings of the 4th International Atmospheric reentry Association Days 2013.04

Research paper (international conference proceedings), Joint Work

An examination of feature detection for real-time visual odometry in untextured natural terrain

Kyohei Otsu, Masatsugu Otsuki, Genya Ishigami, Takashi Kubota

Advances in Intelligent Systems and Computing (Springer Verlag) 208 405 - 414 2013

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 2194-5357

Estimating the position of a robot is an essential requirement for autonomous mobile robots. Visual Odometry is a promising localization method in slippery natural terrain, which drastically degrades the accuracy of Wheel Odometry, while relying neither on other infrastructure nor any prior knowledge. Visual Odometry, however, suffers from the instability of feature extraction from the untextured natural terrain. To date, a number of feature detectors have been proposed for stable feature detection. This paper compares commonly used detectors in terms of robustness, localization accuracy and computational efficiency, and points out their trade-off problems among those criteria. To solve the problem, a hybrid algorithm is proposed which dynamically switches between multiple detectors according to the texture of terrain. Validity of the algorithm is proved by the simulation using dataset at volcanic areas in Japan. © 2013 Springer-Verlag.

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Proposal for the Mars life search equipments : Search for cells, aminoacids and methane

山岸明彦, 吉村義隆, 長沼毅, 宮川厚夫, 出村裕英, 豊田岐聡, 本多元, 小林憲正, 三田肇, 大野宗佑, 石丸亮, 小林喬郎, 戸野倉賢一, 石上玄也, 佐々木晶, 宮本英昭

Planetary People (Journal of the Japanese Society for Planetary Sciences) (The Japanese Society for Planetary Sciences) 21 ( 2 ) 276 - 282 2012.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 0918-273X

火星生命探査機器群提案 -- 細胞，アミノ酸，メタン検出を目的とした --

山岸明彦, 吉村義隆, 長沼毅, 宮川厚夫, 出村裕英, 豊田岐聡, 本多元, 小林憲正, 三田肇, 大野宗祐, 石丸亮, 小林喬郎, 戸野倉賢一, 石上玄也, 佐々木晶, 宮本英昭

日本惑星科学会誌 (The Japanese Society for Planetary Sciences) 21 ( 3 ) 276-282 - 282 2012.09

Research paper (scientific journal), Joint Work, Accepted, ISSN 0918-273X

Advanced Visual Odometry for Planetary Exploration Rover,

Kyohei Otsu, Masatsugu Otsuki, Genya Ishigami, Takashi Kubota

Proceedings of the 11th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2012) 9a-2 2012.09

Research paper (international conference proceedings), Joint Work

LIDAR-based Terrain Mapping and Navigation for Planetary Exploration Rover,

Genya Ishigami, Masatsugu Otsuki, Takashi Kubota

Proceedings of the 11th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2012) 4c-4 2012.09

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author

Testing and Validation of Autonomous Navigation for Planetary Exploration Rover, Cuatro, using Opensource Simulation Tools,

Peshala G. Jayasekara, Genya Ishigami, Takashi Kubota

Proceedings of the 11th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2012) 9c-4 2012.09

Research paper (international conference proceedings), Joint Work

Motion Control with Modification ofAcceleration for planetary Rover on soft Terrain,

Masatsugu Otsuki, Genya Ishigami, Shinichiro Narita, Sachiko Wakabayashi

Proceedings of the 11th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2012) 11a-2 2012.09

Research paper (international conference proceedings), Joint Work

Design, Development, and Mobility test of an Omnidirectional Mobile Robot for Rough Terrain,

Genya Ishigami, Elvine Pineda, Jim Overholt, Greg Hudas, Karl Iagnemma

Proceedings of the 8th International Conference on Field and Service Robotics (FSR 2012) No. 48 2012.07

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

自立移動ロボットによる火山地域の探査活動

大槻真嗣, 石上玄也, 嶋田貴信, 久保田孝, 作田真理子, オリチロンアン, 大津恭平, 清水拓

日本惑星科学会誌 21 ( 2 ) 111-120 2012.06

Research paper (scientific journal), Joint Work, Accepted, ISSN 0918-273X

Multi-material Anisotropic Friction Wheels for Omnidirectional Ground Vehicles

Genya Ishigami, Jim Overholt, Karl Iagnemma

Journal of Robotics and Mechatronics (Fuji Technology Press) 24 ( 1 ) 261-267 - 267 2012.02

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1883-8049

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Field Robotics Technology for Secure System and Exploration from the Earth to the Space,

Takashi Kubota, Masatsugu Otsuki, Genya Ishigami, Takanobu Shimada

Proceedings of the Global COE Symposium on Secure-Life Electronics pp. 3--18 2012.01

Research paper (international conference proceedings), Joint Work

Load Distribution Control of a Six-Wheeled Robotic Vehicle in Rough Terrain

Taizo Kobayashi, Genya Ishigami, Keiji Nagatani, Kazuyoshi Tateyama

Proceedings of 17th International Conference of the International Society for Terrain-Vehicle Systems (ISTVS 2011) Track 2-4 2011.09

Research paper (international conference proceedings), Joint Work, Accepted

Development of Electrical Power Systems for Test-bed Rovers Aiming to Planetary Surface Exploration,

Takanobu Shimada, Masatsugu Otsuki, Hiroyuki Toyota, Genya Ishigami, Takashi Kubota

Proceedings of the 9th European Space Power Conference Ref. 2104158 2011.06

Research paper (international conference proceedings), Joint Work

Experimental Study on Mobility and Navigation for Exploration Rover in Natural Rough Terrain,

Masatsugu Otsuki, Genya Ishigami, Takanobu Shimada, Shogo Takanashi, Orchlon Ann, Takashi Kubota

Proceedings of the 28th International Symposium on Space Technology and Science (ISTS 2011) d-87p 2011.06

Research paper (international conference proceedings), Joint Work, Accepted

Modeling of Flexible and Rigid Wheels for Exploration Rover on Rough Terrain

Genya Ishigami, Masatsugu Otsuki, Takashi Kubota, Karl Iagnemma

Proceedings of the 28th International Symposium on Space Technology and Science (ISTS 2011) d-30 2011.06

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Performance Analysis and Odometry Improvement of an Omnidirectional Mobile Robot for Outdoor Terrain

Genya Ishigami, Elvine Pineda, Jim Overholt, Greg Hudas, Karl Iagnemma

2011 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IEEE) 4091 - 4096 2011

Research paper (international conference proceedings), Joint Work, Lead author, Accepted, ISSN 2153-0858

In this paper an omnidirectional mobile robot that possesses high mobility in rough terrain is presented. The omnidirectional robot has four active split offset caster (ASOC) modules, enabling the robot to move in any planar direction. It also possesses passive suspension articulation, allowing the robot to conform to uneven terrain. The agility of the robot is experimentally evaluated in various configurations. In addition, an odometry method that mitigates position estimation error due to wheel slippage is proposed. A key aspect of the proposed method is to utilize sensory data of wheel velocity, and turning rate around each ASOC pivot shaft, along with kinematic constraints of the robot configuration. Experimental odometry tests with different maneuvers in rough terrain are presented that confirm the utility of the proposed method.

Path Planning and Evaluation for Planetary Rovers Based on Dynamic Mobility Index

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

2011 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IEEE) 601 - 606 2011

Research paper (international conference proceedings), Joint Work, Lead author, Accepted, ISSN 2153-0858

Planetary exploration rovers are required to (semi-) autonomously navigate itself on rough terrain. In such scenario, a feasible path to be followed must be accurately planned, allowing the rover to safely traverse without any mobility hazards. In this paper, a path planning and evaluation strategy that explicitly considers dynamic mobility of the rover is presented. The proposed strategy consists of the following three steps. First, various paths on a given terrain map are generated with varying weighting factors for path planning algorithm. Each path is then examined through complete dynamic simulations of the rover in which the rover travels along with the path. The simulation result provides a metric for robotic mobility. The metric, termed a dynamic mobility index, consists of stability of the rover, wheel slippage, elapsed time, and energy consumption. All of the paths generated are quantitatively evaluated based on the dynamic mobility index, and then, the most feasible path between them is obtained. Demonstrations for the path planning and evaluation are presented in this paper that confirms the validity of the proposed strategy.

Multi-material Anisotropic Friction Wheels for Omnidirectional Ground Vehicles,

Genya Ishigami, Jim Overholt, Karl Iagnemma

Proceedings of the 5th International Conference on Advanced Mechatronics pp. 658--662 2010.10

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Development of a Visual Odometry System for a Wheeled Robot on Loose Soil Using a Telecentric Camera

Keiji Nagatani, Ayako Ikeda, Genya Ishigami, Kazuya Yoshida, Isaku Nagai

Advanced Robotics (TAYLOR & FRANCIS LTD) 24 ( 8-9 ) 1149-1167 - 1167 2010.05

Research paper (scientific journal), Joint Work, Accepted, ISSN 0169-1864

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Statistical Mobility Prediction for Planetary Surface Exploration Rovers in Uncertain Terrain,

Genya Ishigami, Gaurav Kewlani, Karl Iagnemma

Proceedings of the 2010 IEEE International Conference on Robotics and Automation (ICRA 2010) pp. 588--593 2010.05

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Odometry Correction Using Visual Slip-Angle Estimation for Planetary Rovers

Giulio Reina, Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Advanced Robotics (VSP BV) 24 ( 3 ) 359-385 - 385 2010.02

Research paper (scientific journal), Joint Work, Accepted, ISSN 0169-1864

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Design and Analysis of a Soft Mobile Robot Composed of Multiple Thermally Activated Joints Driven by a Single Actuator

Nadia Cheng, Genya Ishigami, Stephan Hawthorne, Hao Chen, Malik Hansen, Maria Telleria, Robert Playter, Karl Iagnemma

2010 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA) (IEEE) 5207 - 5212 2010

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 1050-4729

Soft robotic systems have applications in industrial, medical, and security applications. Many applications require these robots to be small and lightweight. One challenge in developing a soft robotic system is to drive multiple degrees-of-freedom (DOF) with few actuators, thereby reducing system size and weight. This paper presents the analysis and design of an inchworm-like mobile robot that consists of multiple, independent thermally activated joints but is driven by a single actuator. To realize control of this under-actuated system, a solder-based locking mechanism has been developed to selectively activate individual joints without requiring additional actuators. The design and performance analysis of a prototype mobile robot that is capable of inchworm-like translational and steering motion is described. The design of novel "feet" with anisotropic friction properties is also described.

Predictable Mobility A Statistical Approach for Planetary Surface Exploration Rovers in Uncertain Terrain

Genya Ishigami, Gaurav Kewlani, Karl Iagnemma

IEEE ROBOTICS & AUTOMATION MAGAZINE (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC) 16 ( 4 ) 61 - 70 2009.12

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1070-9932

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Slope Traversal Controls for Planetary Exploration Rover on Sandy Terrain

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Journal of Field Robotics (WILEY-BLACKWELL) 26 ( 3 ) 264-286 - 286 2009.03

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1556-4959

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Stochastic Mobility-based Path Planning in Uncertain Environments

Gaurav Kewlani, Genya Ishigami, Karl Iagnemma

2009 IEEE-RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IEEE) 1183 - 1189 2009

Research paper (international conference proceedings), Joint Work, Accepted

The ability of mobile robots to generate feasible trajectories online is an important requirement for their autonomous operation in unstructured environments. Many path generation techniques focus on generation of time- or distance-optimal paths while obeying dynamic constraints, and often assume precise knowledge of robot and/or environmental (i.e. terrain) properties. In uneven terrain, it is essential that the robot mobility over the terrain be explicitly considered in the planning process. Further, since significant uncertainty is often associated with robot and/or terrain parameter knowledge, this should also be accounted for in a path generation algorithm. Here, extensions to the rapidly exploring random tree (RRT) algorithm are presented that explicitly consider robot mobility and robot parameter uncertainty based on the stochastic response surface method (SRSM). Simulation results suggest that the proposed approach can be used for generating safe paths on uncertain, uneven terrain.

Action Planner of Hybrid Leg-Wheel Robots for Lunar and Planetary Exploration.

Eric Rohmer, Giulio Reina, Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Proceedings of the 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems 3902 - 3907 2008.10

Research paper (international conference proceedings), Joint Work, Accepted

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Trafficability Analysis for Lunar/Planetary Exploration Rover Using Thrust-Cornering Characteristic Diagram Proc. of IEEE/RSJInt

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Conference on Intelligent Robots and Systems 2228 - 2233 2008.09

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

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Sensing Position Planning for Lunar Exploration Rovers2008

Andres Mora, Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

IEEE International Conference on Mechatronics and Automation TA3-3 2008.08

Research paper (international conference proceedings), Joint Work, Accepted

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Slope Traversal Experiments with Slip Compensation Control for Lunar/Planetary Exploration Rover,

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Proceedings of the 2008 IEEE International Conference on Robotics and Automation (ICRA 2008) pp. 2295--2300 2008.05

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Terramechanics-based Analysis and Control for Lunar/Planetary Exploration Robots

Genya Ishigami

東北大学大学院工学研究科航空宇宙工学専攻博士学位論文 2008.02

Doctoral thesis, Single Work, Lead author, Last author, Corresponding author, Accepted

Vision-based Estimation of Slip Angle for Mobile Robots and Planetary Rovers

Giulio Reina, Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

IEEE International Conference on Robotics and Automation 2295 - 2300 2008

Research paper (international conference proceedings), Joint Work, Accepted

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Path Planning for Planetary Exploration Rovers and Its Evaluation Based on Wheel Slip

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Proceedings of the International Conference on Robotics and Automation 2361 - 2366 2007.04

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

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Terramechanics-Based Model for Steering Maneuver of Planetary Exploration Rovers on Loose Soil

Genya Ishigami, Akiko Miwa, Keiji Nagatani, Kazuya Yoshida

Journal of Field Robotics (JOHN WILEY & SONS INC) 24 ( 3 ) 233--250 - 250 2007.03

Research paper (scientific journal), Joint Work, Lead author, Corresponding author, Accepted, ISSN 1556-4959

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Path Following Control with Slip Compensation on Loose Soil for Exploration Rover

Genya Ishigami, Keiji Nagatani, Kazuya Yoshida

Proceedings of the 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems 5552 - 5557 2006.10

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

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Terramechanics-Based Analysis on Slope Traversability for a Planetary Exploration Rover

Ishigami, G., Miwa, A., Nagatani, K., and Yoshida, K.,

Proceedings of the 25th International Symposium on Space Technology and Science (ISTS 2006) pp. 1025--1030 2006.06

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Terramechanics-based analysis and traction control of a lunar/planetary rover

Kazuya Yoshida, Toshinobu Watanabe, Noriyuki Mizuno, Genya Ishigami

FIELD AND SERVICE ROBOTICS: RECENT ADVANCES IN RESEARCH AND APPLICATIONS (SPRINGER-VERLAG BERLIN) 24 225 2006

Research paper (international conference proceedings), Joint Work, Accepted, ISSN 1610-7438

This paper presents analysis of traction mechanics and control of a lunar/planetary rover based on the models obtained from terramechanics. A case study has been conducted for a rover test bed to negotiate a slope of loose soil such as regolith that covers most of lunar surface. The tire traction force is modeled as a function of the vertical load and slip ratio of the wheel. Bekker's terramechanic formulae are employed to derive an improved practical model that calculates net traction force, referred to as Drawbar Pull, with a reasonable precision. Experiments are carried out in two phases. First, the physical behavior of a wheel on loose soil is observed using a single-wheel test bed, then the empirical parameters of the tire and soil are identified. Second, the slope climbing capability is studied by using a rover test bed that has independently driven four wheels. The traction margin and slip margin are defined to be used in a traction control. In the slope experiment, it turned out that the climbing capability was saturated at 14 degrees due to the lack of enough driving torque in wheels. But theoretical investigation suggests that this is not the limitation of terrain trafficability and climbing capability can be improved by increased driving torque and proper load distribution.

Steering Trajectory Analysis of Planetary Exploration Rovers Based on All-Wheel Dynamics Model

Genya Ishigami, Akiko Miwa, Kazuya Yoshida

The 8th Int. symposium on Artificial Intelligence, Robotics and Automation in Space SP-603 1 - 8 2005.09

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author

Steering Characteristics of a Rigid Wheel for Exploration on Loose Soil

Kazuya Yoshida, Genya Ishigami

Proceedings of 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems 3995 - 4000 2005

Research paper (international conference proceedings), Joint Work, Accepted

Steering characteristics of an exploration rover on loose soil based on all-wheel dynamics model

G Ishigami, K Yoshida

2005 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS, VOLS 1-4 (IEEE) 2041 - 2046 2005

Research paper (international conference proceedings), Joint Work, Lead author, Accepted

In this paper, steering characteristics of an exploration rover on loose soil is studied. Analysis of the steering characteristics is a key to plan and control the motion trajectory of a rover. Traditionally, such analysis has been made based on a model called "bicycle model" In that model, a four-wheel car-like vehicle is approximated by a two-wheel bicycle-like vehicle with the fore-wheels and the rear-wheels paired. However, the bicycle model does not show a good performance when a vehicle travels off-road. In order to analyze the steering characteristics of a vehicle on loose soil, the authors develop a model that respects the dynamics of each wheel's slip and skid behavior. The developed model is called All-Wheel Dynamics Model. In the all-wheel dynamics model, the behavior of each wheel on loose soil is modeled based on terramechanics. The motion trajectory of the vehicle is obtained by numerical simulation using the wheel-and-vehicle dynamics model. The validity of the proposed model is examined by the experiments of a wheel and a vehicle using simulated lunar-surface soil. The experimental results show that the proposed model provides a better approximation than the traditional bicycle model.

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Long Range Navigation on Desert by a Dual-Wheel Micro Rover

Genya ISHIGAMI, Noriyuki MIZUNO, Akiko MIWA, Kazuya YOSHIDA

The 24th International Symposium on Space Technology and Science, Miyazaki, Japan 1 - 6 2004

Research paper (international conference proceedings), Joint Work, Lead author, Corresponding author, Accepted

Terramechanics-Based Analysis for Slope Climbing Capability of a Lunar/Planetary Rover

K.Yoshida, N.Mizuno, G.Ishigami, A.Miwa

The 24th International Symposium on Space Technology aned Science,2004 k-6, (6 pages) 2004

Research paper (international conference proceedings), Joint Work, Accepted

Slip, Traction Control, and Navigation of a Lunar Rover

Yoshida, K., Watanabe, T., Mizuno, N., and Ishigami, G.,

Proceedings of the 7th International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2003) AS21 2003.06

Research paper (international conference proceedings), Joint Work, Last author

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