Details of a Researcher - Ohnishi, Kouhei

Papers - Ohnishi, Kouhei

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Development of microsurgical forceps equipped with haptic technology for in situ differentiation of brain tumors during microsurgery

Ezaki T., Kishima K., Shibao S., Matsunaga T., Pareira E.S., Kitamura Y., Nakayama Y., Tsuda N., Takahara K., Iwama T., Sampetrean O., Toda M., Ohnishi K., Shimono T., Sasaki H.

Scientific Reports 14 ( 1 ) 2024.12

The stiffness of human cancers may be correlated with their pathology, and can be used as a biomarker for diagnosis, malignancy prediction, molecular expression, and postoperative complications. Neurosurgeons perform tumor resection based on tactile sensations. However, it takes years of surgical experience to appropriately distinguish brain tumors from surrounding parenchymal tissue. Haptics is a technology related to the touch sensation. Haptic technology can amplify, transmit, record, and reproduce real sensations, and the physical properties (e.g., stiffness) of an object can be quantified. In the present study, glioblastoma (SF126-firefly luciferase-mCherry [FmC], U87-FmC, U251-FmC) and malignant meningioma (IOMM-Lee-FmC, HKBMM-FmC) cell lines were transplanted into nude mice, and the stiffness of tumors and normal brain tissues were measured using our newly developed surgical forceps equipped with haptic technology. We found that all five brain tumor tissues were stiffer than normal brain tissue (p < 0.001), and that brain tumor pathology (three types of glioblastomas, two types of malignant meningioma) was significantly stiffer than normal brain tissue (p < 0.001 for all). Our findings suggest that tissue stiffness may be a useful marker to distinguish brain tumors from surrounding parenchymal tissue during microsurgery, and that haptic forceps may help neurosurgeons to sense minute changes in tissue stiffness.

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Analysis of Grinding Motion using Force/Tactile Sensation

Kitamura T., Hachimine T., Matsubara T., Saito Y., Asai H., Ohnishi K.

IEEE International Symposium on Industrial Electronics 2024

ISSN 21635137

Understanding human movements is essential for teaching skills to novices and enabling robots to learn. Traditional movement analysis often relies on visual data, but incorporating force/tactile information is vital for object interactions. The spring-mass-damper model, used to represent force/tactile data, assumes continuous contact and consistent material properties, which are limitations when analyzing grinding actions that frequently alternate between contact and non-contact. This study proposes analyzing grinding by quantifying force/tactile sensations as the ratio of the root mean square (RMS) values of force to speed, using absolute impedance to measure sensations irrespective of contact. Findings indicated that operators typically initiate a pressing motion several seconds after detecting contact, and their reactions to samples of varying hardness differ significantly. These observations suggest a detailed breakdown of human grinding skills is feasible, highlighting the potential of force/tactile information in enhancing skill transfer to beginners and robots.

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Validation of a surgical drill with a haptic interface in spine surgery

Yamanouchi K., Takano S., Mima Y., Matsunaga T., Ohnishi K., Matsumoto M., Nakamura M., Shimono T., Yagi M.

Scientific Reports (Scientific Reports) 13 ( 1 ) 2023.12

Real haptics is a technology that reproduces the sense of force and touch by transmitting contact information with real objects by converting human movements and the feel of the objects into data. In recent years, real haptics technology has been installed in several surgical devices. A custom-made surgical drill was used to drill into the posterior lamina to verify the time required for penetration detection and the distance the drill advanced after penetration. A surgeon operated with the drill and the same aspects were measured and verified. All experiments were performed on female miniature pigs at 9 months of age with a mean body weight of 23.6 kg (range 9–10 months and 22.5–25.8 kg, n = 12). There were statistically significant differences in the average reaction time and the distance travelled after penetration between a handheld drill and the drill with the penetration detection function (p < 0.001). The reaction time to detect penetration and the distance after penetration were both significantly improved when compared with those of the handheld surgical drill without the penetration detection function, with mean differences of 0.049 ± 0.019 s [95% CI 0.012, 0.086 s] and 2.511 ± 0.537 mm [95% CI 1.505, 3.516 mm]. In this study, we successfully conducted a performance evaluation test of a custom-made haptic interface surgical drill. A prototype high-speed drill with a haptic interface accurately detected the penetration of the porcine posterior lamina.

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Handheld Haptic Drill Simulator Using Visual Servoing System for Axial Force Presentation

Matsunaga T., Takano S., Shimono T., Ohnishi K., Yagi M., Nakamura M.

IEEE International Symposium on Industrial Electronics (IEEE International Symposium on Industrial Electronics) 2023-June 2023

Bone cutting tasks in spinal surgery require advanced skills to operate a handheld drill device. Since there is a risk to injure the spinal cord, both of support for surgeons and enhancement of surgeon's skills are important for safer surgery. Therefore, orthopedic surgical robots and devices have been studied and developed. In this study, a handheld haptic drill simulator using a visual servoing system is developed. A stereo camera is used to acquire the position and posture of a handheld drill device used as a haptic interface. Voxel representation is applied to virtual objects in environment simulation. Axial cutting force is fed back to the operator via the haptic interface, while virtual environment images are presented by a two-dimensional display. A small virtual object composed of voxels is cut by the drill device in the experiment. The feasibility of the handheld haptic drill simulator and the applicability of the handheld haptic drill devices are confirmed by the experimental results.

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Verification of Anode Position and Generated Force Vector of EHD at Wire-cylinder Electrode

Kitamura T., Katagiri H., Yashita S., Saito Y., Asai H., Ohnishi K., Nozaki T.

IEEE International Symposium on Industrial Electronics (IEEE International Symposium on Industrial Electronics) 2023-June 2023

Electrohydrodynamics (EHD) is a thrust force produced when high voltage is applied to two electrodes, and actuators using EHD are expected to reduce equipment size and the effects of friction. However, the EHD effect of multiple anode electrodes has yet to be verified and should be considered when fabricating a multi-degree-of-freedom actuator using EHD. This paper examines the relationship between the applied voltage and the generated EHD to verify the effect of multiple anode electrodes on the EHD. Experiments were conducted using a device with two anode electrodes at right angles and another with two parallel electrodes. The results showed that the two anode electrodes placed at right angles interfered with each other, and the generated forces were not superposed. The direction of the generated force was approximately 45 deg. When the electrodes were placed horizontally, it was confirmed that the generated forces were superposed, indicating that the arrangement, not the number of anode electrodes, was the cause of the interference.

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Development of Orthopedic Haptic Drill for Spinal Surgery with Penetration Detection Scheme based on Viscosity Estimation

Takano S., Shimono T., Matsunaga T., Yagi M., Ohnishi K., Nakamura M., Mima Y., Yamanouchi K., Ikeda G.

IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM (IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM) 2023-June 194 - 200 2023

In orthopedic surgery, making an incision into the spine involves a risk of injury to the spinal cord. In addition, surgeons must determine penetration into the bone using only their haptic senses. This imposes a heavy burden on the surgeon. In this study, an orthopedic haptic drill with a penetration detection scheme based on viscosity estimation is proposed. This drill detects penetration by monitoring changes in the position and force of the linear motor in the drill. The threshold values are automatically optimized according to the estimated viscosity of the object being cut. Therefore, the proposed drill does not require prior setup of the parameters in accordance with the object being cut. The utility of the proposed drill is verified experimentally.

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Machine Learning-Based Performance Improvement of Bilateral Teleoperation with Hydraulic Actuator

Saito Y., Asai H., Kitamura T., Ohnishi K.

Proceedings - 2023 IEEE International Conference on Mechatronics, ICM 2023 (Proceedings - 2023 IEEE International Conference on Mechatronics, ICM 2023) 2023

Teleoperation with hydraulic actuator is useful for human action augmentation. However, disturbances in hydraulic actuators are complex and accurate estimation of external forces is difficult. In this paper, a reaction force observer and machine learning are combined to achieve high accuracy sensorless force estimation in hydraulic actuator. Furthermore, this method is applied to a bilateral control system to improve its performance. While there are many machine learning methods, this paper uses a Long Short-Term Memory network, a type of recurrent neural network that excels at inferring time series data, to accurately infer the hysteresis characteristics of disturbances in hydraulic actuator. Furthermore, 4ch bilateral control based on oblique coordinate control is used to realize teleoperation. In the experiment, a friction model-based compensation method and a machine learning-based compensation method are applied to bilateral control, and the performance of each method is evaluated.

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Development and validation of a surgical drill with a haptic interface in spine surgery

K Yamanouchi, S Takano, T Matsunaga, M Matsumoto, M Murakami, T Shimono, M Yagi, K Ohnishi

(researchsquare.com) 2022.05

Joint Work, Last author

Experimental Verification of a Novel Continuously Variable Transmission with Electro-Hydrosttic Actuator

H Asai, K Sugihara, T Kitamura, Y Saito, K Ohnishi, T Nozaki

20220220 (IEEE) 2022.02

Joint Work, Last author

Object Detection in Motion Reproduction System with Segmentation Algorithm

X Sun, T Nozaki, T Murakami, K Ohnishi

2022.02

Joint Work, Last author

Performance Impruvement of Bilateral Teleoperation with Hydraulic Actuator by Friction Compensation

Y Saito, H Asai, T Kitamura, W Iida, T Nozaki, K Ohnishi

2022.02

Joint Work, Last author

Quantification of Force/Tactile Sensation

Y.Saito, K Ohnishi

IEEJ Journal of Industry Applications (IEEJ ) 12 ( 2 ) 125 - 130 2022

Joint Work, Last author, ISSN 21871094

The force/tactile sensation (hereafter referred to as f/t sensation) has not been well defined for a long time. In the applications of real haptics, it is necessary to quantitatively evaluate the quality of the f/t sensation. The paper proposes the definition of f/t sensation as the stimulus signal. Accordingly, the instantaneous value of the stimulus signal of the f/t sensation represents the simultaneous ratio of the value of reaction force and the value of velocity. If the contact target is modeled as an inertia-damper-spring model, the stimulus signal of the f/t sensation is expressed as the equivalent circuit of the sum of the impedance (or admittance) and the voltage source (or the current source). The definition of the stimulus signal of the f/t sensation in frequency area clarifies the physical meaning. The paper presents the experimental results that confirm the viability of this novel definition on the stimulus signal of the f/t sensation.

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Validation of a Property Estimation Method Based on Sequential and Posteriori Estimation

Kitamura T., Saito A., Yamazaki K., Saito Y., Asai H., Ohnishi K.

IECON Proceedings (Industrial Electronics Conference) (IECON Proceedings (Industrial Electronics Conference)) 2022-October 2022

ISSN 21624704

Robots are being developed to perform tasks in homes and factories autonomously. Several studies have examined motion generation based on haptic information, and some studies consider the environment as physical property information. However, there is a trade-off between the accuracy and the time required for the physical property estimation. Therefore, in this study, we propose a method for estimating physical properties based on training the relationship between the two estimation models. The first is a fast sequential estimation model, and the second is a highly accurate posterior estimation model. Training the relationship between the two models makes highly accurate sequential property estimation possible. Validation results showed improved accuracy of property estimation for learning samples and some untrained samples.

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Stability and Robustness of the Disturbance Observer-Based Motion Control Systems in Discrete-Time Domain

Sariyildiz E., Hangai S., Uzunovic T., Nozaki T., Ohnishi K.

IEEE/ASME Transactions on Mechatronics (IEEE/ASME Transactions on Mechatronics) 26 ( 4 ) 2139 - 2150 2021.08

ISSN 10834435

This article analyses the robust stability and performance of the disturbance observer (DOb) based digital motion control systems in the discrete-time domain. It is shown that the phase margin and the robustness of the digital motion controller can be directly adjusted by tuning the nominal plant model and the bandwidth of the observer. However, they have the upper and lower bounds due to robust stability and performance constraints as well as the noise sensitivity. The constraints on the design parameters of the DOb change when the digital motion controller is synthesized by measuring different states of a servosystem. For example, the bandwidth of the DOb is limited by the noise sensitivity and waterbed effect when the velocity and position measurements are employed in the digital robust motion controller synthesis. The robustness constraint due to the waterbed effect is removed when the DOb is implemented by acceleration measurement. The design constraints on the nominal plant model and the bandwidth of the observer are analytically derived by employing the generalized Bode integral theorem in discrete time. The proposed design constraints allow one to systematically synthesize a high-performance DOb-based digital robust motion controller. The experimental results are given to verify the proposed analysis and synthesis methods.

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A Method to Contact with Real Environment through Virtual Object by Hidden End Effector in Teleoperation with Augmented Reality

Matsunaga T., Shimono T., Ohnishi K.

IEEE International Symposium on Industrial Electronics (IEEE International Symposium on Industrial Electronics) 2021-June 2021.06

Teleoperation systems utilizing master-slave systems and video apparatuses are useful for tasks requiring human judgments and skills. Haptic sensation can be transmitted by master-slave systems implementing bilateral control, while visual information is shown to operators by video apparatuses. Furthermore, augmented reality (AR) can be presented to operators by processing visual and haptic information. Operators can move virtual objects in real environment by using teleoperation systems. However, virtual objects cannot interact with real environment, although rendering of virtual objects can be changed according to the positional relation to real environment. The noninteractive characteristics of AR between real and virtual objects restricts application of teleoperation systems. In this paper, a method that enables operators to contact with real environment through a virtual object is proposed. Bilateral control with compliance controller is implemented to a one degree-of-freedom master-slave system as haptic AR. The end effector of the slave robot is hidden by image processing. Instead of the real end effector, a virtual end effector with a virtual object is presented as visual AR. Operators can perform contact motion by the teleoperation system, as if reaction force from real environment is presented through the virtual object. The feasibility of the proposed method is confirmed by an experiment.

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Multi functional drill incorporating linear motor for haptic surgical instrument and simulator

Matsunaga T., Shimono T., Ohnishi K., Takano S., Kobayashi H., Yagi M., Nakamura M.

2021 IEEE International Conference on Mechatronics, ICM 2021 (2021 IEEE International Conference on Mechatronics, ICM 2021) 2021.03

ISSN 9781728144429

In orthopedic surgery, tasks to cut the vertebra by surgical drills involve the risk of the spinal cord injury. Since the spinal cord injury causes motor and sensory disorder to patients, orthopedists who perform spine surgery must have skills to achieve tasks using surgical drills. Although robotic technologies is being applied to orthopedic surgical operations, support for surgeons in delicate tasks requiring surgeon's skills is insufficient. In this study, a multi functional drill available for both a surgical instrument and a simulator is presented. A linear motor incorporated in the proposed device used as a surgical instrument provides support for operators, while measuring position information and estimating force information. Furthermore, environmental information can be abstracted by haptic information such as position and force information. Virtual environment reproduced by the environmental information is presented by the proposed device used as a simulator. The feasibility of the multi functional drill is confirmed by utilizing functions as a surgical instrument and a simulator.

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Development of multi degrees-of-freedom haptic forceps robot with three actuated fingers

Matsunaga T., Shimono T., Ohnishi K.

IEEJ Journal of Industry Applications (IEEJ Journal of Industry Applications) 10 ( 2 ) 247 - 253 2021.03

ISSN 21871094

Surgical robots have been studied and developed to assist surgeons. Master-slave flexible forceps robots that are components of a flexible endoscopic surgical robot are useful to realize novel minimally invasive surgical procedures that are difficult for conventional rigid medical devices. Although driving force for the tip portion of a flexible forceps robot is mechanically transmitted by wires through the flexible portion, friction and backlash changed by the posture of the flexible portion make it difficult to realize precise end effector control. Furthermore, transmission of haptic sensation is necessary to realize safer operation. In this study, a multi degrees-of-freedom (DoF) haptic forceps robot with three fingers is presented as an end effector of a flexible forceps robot. Transmission of driving force in flexible structure that causes performance deterioration is eliminated by arranging motors near the end effector. To transmit haptic sensation to operators, bilateral control is implemented to a master-slave system composed of the haptic forceps robot and a multi DoF input device. Additionally, control on modal space is implemented to verify finger dexterity. The utility of the haptic forceps robot is experimentally validated.

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A study on safe forseps grip force for the intestinal tract using haptic technology

K Yatabe, S Ozawa, J Oguma, S Hiraiwa, S Tomita, T M Yokoyama, T Shiimono, K Ohnishi

Invasive Therapy (Taylor and Fransis) 2021.01

Joint Work, Last author

Bilateral teleoperatìon system with extension of information based on visual information

Matsunaga T., Shimono T., Ohnishi K.

Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering (Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering) 87 ( 4 ) 380 - 387 2021

ISSN 09120289

Master-slave teleoperatìon robots are useful for tasks that require human judgments and skills. Haptic sensation can be transmitted between a master and a slave by implementing bilateral control. Besides, visual information of the slave side that cannot be directly seen from the master side is presented by devices such as cameras, endoscopes, and displays. Therefore, advanced support of the teleoperatìon robots for operators can be expected by utilizing extended visual and haptic information. In this paper, a master-slave teleoperation system with ability to extend information transmitted to operators is proposed. The teleoperation system consists of one degree of freedom master-slave system implementing bilateral control based on robust acceleration control and an image processing system. To support operators, visual and haptic augmented reality is generated by image processing, micro-macro bilateral control, and compliance control. In addition, a design method of position and force scaling for micro-macro bilateral control according to magnification ratio of image is presented. The utility of the proposed bilateral teleoperation system is verified by experiments.

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Online Motion Modification by Operator in Motion Reproduction System

Sun X., Nozaki T., Ohnishi K., Murakami T.

IECON Proceedings (Industrial Electronics Conference) (IECON Proceedings (Industrial Electronics Conference)) 2020-October 668 - 673 2020.10

ISSN 9781728154145

© 2020 IEEE. This paper proposes a novel online motion modification method in motion reproduction system. Motion reproduction is used to reproduce human motion saved through bilateral control. Bilateral control is a teleoperation which can transmit both position and force. Human judgement is needed for compensating the saved motion when the environment is different. However, conventional motion reproduction system only relies on saved motion or environment in slave side. Therefore operators in master side cannot modify the motion after motion has been saved. Instead of just reproducing the motion data, the proposed method adds master system at motion reproduction phase so that an operator can modify the motion. If the master system is simply added to motion reproduction system, the operator's motion and saved motion will interfere each other. Therefore, we propose to use weightings to suppress the interference. Simulated results validates the effectiveness of the proposal.

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