Details of a Researcher - ISHIGAMI Genya

Papers - ISHIGAMI Genya

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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

<p><b>（要旨） </b>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．</p>

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

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

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 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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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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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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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 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 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

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