Published papers

© 2019 IEEE. Bilateral control can realize haptic feedback required for securing safety and diversity in teleoperation by robots. Since conventional approaches are based on a servo controller which has high-performance current control or torque control, there is a barrier for advancing into society. The objective of this paper is to propose a design method of the bilateral controller using velocity control driver to achieve haptic feedback. The velocity control driver such as an inverter is widely used in the industrial fields. In the proposed method, a reaction force observer modified for velocity control driver is used to estimate environmental reaction force. The control system is constructed by applying the concept of hybrid control which controls velocity and force independently, and the concept of modal space which separates motions into functions is also applied. Furthermore, the proposed bilateral controller is designed based on the ideal conditions of operationality and reproducibility. The validity of the proposal is verified through a simulation and an experiment. The obtained results show that the proposed controller successfully achieves the teleoperation with haptic feedback using velocity control driver.

© 2019 IEEE. Bilateral control is getting much attention as a key technology in teleoperation. A reproducibility is one of the performance indices of bilateral teleoperation, and four-channel acceleration-based bilateral control (4ch ABC) which has a high reproducibility with wide bandwidth enables operators to feel environmental impedance, clearly. Both position control and force control are required for the 4ch ABC, and a PD controller and a P controller are often utilized with a disturbance observer (DOB) and a reaction force observer (RFOB). This paper discusses how operators can feel environmental impedance with wide bandwidth in the 4ch ABC. A damping ratio of a PD controller has been, conventionally, set about 1 by imitating a traditional design principle of servo control. This paper theoretically reveals that a velocity feedback gain of a PD controller affects a bandwidth of reproducibility as a synergy with observer gains of a DOB, and a PD controller using a high velocity feedback gain is introduced. The validity of the theoretical analysis is confirmed by simulations and experimental results.

© 2019 IEEE. Teleoperation technology is widely employed in the fields of industry and human support. Bilateral control, which is one of the possible methods to achieve teleoperation, enables mutual transmission of operational force of an operator and reaction force from remote environment. However, teleoperation often involves non negligible communication delays, due to the limits of the communication networks. As a countermeasure against communication delays, bilateral control using a force-control-based communication delay compensation has been proposed. This approach is effective in stabilizing system behavior and in maintaining the force states, so that operator's operational force and reaction force from environment can act in pairs and opposite direction, even during contact tasks. In this paper, we introduce a bilateral control that makes use of a force-control-based communication delay compensation, with a new control structure in which structural redundancy of conventional system is removed. The proposed bilateral control system demonstrates through experiments a stable teleoperation and an accurate force matching performance through experiments.

©2020 The Institute of Electrical Engineers of Japan. A bilateral control system aims at realizing a fine haptic transmission between a human operator and a remote environment object. Such a system is expected to realize multiple requirements in practical applications, and the architecture design based on a layer structure has to be considered. This paper treats a surgery robot system as an example, and its system has two requirements: "large workspace"and "fine haptic sensation". Using the conventional bilateral control system to realize these requirements simultaneously is difficult because mechanical and control designs are separately discussed. At the same time, a system that has multiple requirements such as a fine/coarse system is often designed only using position information. This study proposed to consider not only mechanical/control design but also the position/force information simultaneously from the perspective of an architecture design. The proposed architecture decomposes the functions into each motor/robot by defining roles and combining each role in the layer structure. The advantage of the proposal is that a complex system can be designed as a entire by combining multiple sub-functions that can be simply designed. As a result, the surgery robot system is designed by considering its requirements, and the experiments are carried out to verify if the requirements are satisfied. Â

© 2020 IEEE. Recently, the demand for collaborative robot is increasing. Most of them are smaller to conventional industrial robots. In order to support humans in various field, it is required that they acquire flexible and dexterous motions. The soft motion based on force control will be one of keys to realize such a motion. However, the introduction of force control leads to a decrease in the rigidity of the system, which results in a decrease in positioning accuracy. This poor position tracking accuracy could cause the drop of grasped object, and it leads property damage accidents. Recently, there have been much discussions about the responsibility, handling, and risk management of accident caused by robots. As a solution, we propose the automatic grasping position adjustment for robotic hand to prevent the grasped object from falling. By observing the center of gravity and adjusting its position, the system attempts to shift unstable grasping position to stable position. This paper shows the automatic grasping position adjustment method. Then the performance of proposed method is verified by using actual robotic hand.

© 2020 Wiley Periodicals, Inc. Robotic technologies are being increasingly utilized for medical treatments to support surgeons and reduce the burden on patients. Flexible endoscopic surgical systems with an endoscope and flexible forceps robots are state-of-the-art devices that are expected to realize more difficult and less invasive surgery. Surgeons teleoperate these flexible forceps robots as their own hands and conduct various medical tasks. The wire-driven mechanism is applied to many flexible forceps robots to transmit the driving force to the tip of the robots in a narrow space. However, the flexible structure makes it difficult to control the wire-driven robots and implement the haptic technologies to realize safer surgery. In this paper, a force sensor-less, small-diameter flexible forceps robot with the ability to transmit haptic sensation is presented. The driving part at the tip of the flexible part, composed of a small actuator with a reduction mechanism, realizes the miniaturization of the robot. Haptic information is estimated by low-resolution position information. The bending of the flexible part with electric wires does not deteriorate the performance of the end effector. The performance of the haptic flexible forceps robot is evaluated through experiments.

© 2019 The Institute of Electrical Engineers of Japan. Robotic technologies are being increasingly utilized for medical treatments to support surgeons and reduce the burden to patients. Flexible endoscopic surgical systems with an endoscope and flexible forceps robots are state-of-the-art devices that are expected to realize more difficult and less invasive surgery. Surgeons teleoperate these flexible forceps robots as their own hands and conduct various medical tasks. The wire-driven mechanism is applied to many flexible forceps robots to transmit the driving force to the tip of the robots in a narrow space. However, the flexible structure makes it difficult to control the wire-driven robots and implement the haptic technologies to realize safer surgery. In this paper, a force sensor-less, small-diameter flexible forceps robot with the ability to transmit haptic sensation is presented. The driving part at the tip of the flexible part, composed of a small actuator with a reduction mechanism, realizes the miniaturization of the robot. Haptic information is estimated by low resolution position information. The bending of the flexible part with electric wires does not deteriorate the performance of the end effector. The performance of the haptic flexible forceps robot is evaluated through experiments.