Tomoyuki Shimono

Flexible Controller Design of Bilateral Grasping Systems Based on a Multilateral Control Scheme

This paper describes a novel bilateral grasping control system including master-slave robots with different degree of freedom. The master and slave controllers are designed based on a multilateral control scheme. Decoupling design of force and position controllers is realized by mode transformation using the discrete Fourier transform matrices and a disturbance observer. In the proposed system, a human operator manipulates two master robots, and three slave robots grasp an object cooperatively. The proposed system makes it possible to grasp an object tightly in the slave side and to transmit feeling of grasping to a human operator vividly. The validity of the proposed method is shown by numerical and experimental results.

Transmission of force sensation by micro-macro bilateral control with scaling of control gains

A micro-macro bilateral system consists of master and slave system of different sizes. Thus, it is vital for the micro- macro bilateral control to use appropriate scaling factors of position and force responses, And the appropriate control gains should be used according to the scaling gains. The proposed method is designed based on ideal reproducibility and ideal operationality of micro-macro bilateral control system. By deriving the control system to satisfy the ideal reproducibility, scaling factors of control gains are obtained. In this paper, the frequency analysis results of hybrid parameters are shown to verify the validity of the proposed method. And the proposed method is applied to the experimental micro-macro bilateral system and the results of the experimentation with real biological environments is shown. Moreover, the impedances of the contacted objects are estimated and compared.

Transmission of Force Sensation by Micro-Macro Bilateral Control with Respect to Standardized Modal Space

This paper proposes novel micro-macro bilateral control architecture with respect to standardized modal space. In bilateral control, force control and position control must be realized simultaneously in the same real axis. In this paper, force control is achieved in virtual common mode space and position control is attained in virtual differential mode space respectively. In the modal space, common mode and differential mode are orthogonal. Thus, force control and position control are able to be realized simultaneously. Additionally, the standardization matrix that harmonizes the standard of macro master system with the standard of micro slave system in the modal space is proposed as well. With the proposed method, the transmission of force sensation from the real micro environment is achieved. To verify the validity of the proposed method, experimental results are shown.

Abstraction of Action Components Unconstrained by Alignment of Haptic Sensing Points

This paper proposes an abstraction method of independent components of human action from haptic information. First, the haptic information is obtained using a haptic device (haptic bilateral system). Second, the action components can be abstracted from the haptic information by using the proposed method. The proposed method achieves abstraction of the action components unconstrained by the alignment of sensing points with simple calculations. The proposed method is applied for grasping and manipulation motions by two- and three-finger robots. The validity of the proposed method is shown by the experimental results.

Task Realization by a Force-Based Variable Compliance Controller for Flexible Motion Control Systems

This paper proposes a task realization method by using a force-based variable compliance controller for flexible motion control systems. In recent years, the robots working in human life space are desirable. Considering the robots working in human life space, they should achieve the safety motion. From this viewpoint, one of the key technologies is flexible motion control system. Of course, task realization instead of human beings is important. Therefore, it is necessary to propose the realization method of several tasks for the flexible motion control systems. In this paper, two robot tasks are defined: “approach task” and “pushing task.” The approach task is the motion for a robot to approach an environment and not to contact the environment. On the other hand, the pushing task is the motion for the robot to contact and push the environment in order to achieve the several tasks. For the realization of the several tasks to the environment, it is necessary to achieve both the position control during the approach task and the force control during the pushing task. Therefore, the controller has to be modified depending on the contact state, which means whether the robot is in contact with the environment or not. In order to modify the controller, the variable compliance gain which is varied according to the contact state is proposed. Focusing on the approach task, the position control which is equivalent to the conventional position-based compliance method is achieved by using the proposed method. On the other hand, the proposed controller is suitable for the pushing task compared with the conventional position-based compliance controller since the proposed controller is based on the force control. Therefore, several tasks which include the position tracking and the contact with the environment are actualized by using the proposed method. In addition, the performance analysis by a Bode diagram and stability analysis by root loci are conducted. The validity of the proposed method is confirmed from the experimental results.

Haptics for medical applications

Robots and intelligent machines in the future should adapt themselves autonomously to the open environment in order to realize physical support for human activities. In addition, the physical support by them must be based on the individual’s “action” and “sensation” in order that the physical support becomes really human-friendly. Then, the robots must actively recognize the unknown environment according to the individual’s action. They also have to transmit the environmental information obtained to the individual in harmony with their sensations. Since haptic information is so important, as well as visual information and auditory information, the development of realworld haptics is one of the important key issues for the purpose. Haptic information is inherently bilateral, since an action is always accompanied by a reaction. That means that bilateral control with high transparency is necessary to transmit real-world haptic information artificially. A acceleration-based bilateral controller is one of the solutions for realizing high transparency. There remain many issues to solve for the application of haptics to the physical support of actual human activities. A haptic system with high transparency should obtain flexibility in order to extend its function. This article presents flexible actuation techniques that have high force transferability and flexibility in actuators’ arrangements. Furthermore, in order to support human activities in remote environments, bilateral telehaptics over a network is also described. Finally, this article introduces the fundamental techniques in haptics, including several examples of medical applications, since they are the first target of real-world haptics.

A Realization of Haptic Skill Database by Bilateral Motion Control

This paper proposes the novel technology for the haptic skill database. In recent years, skill preservation and skill acquisition have been serious problems in various fields. However, the conventional recording technology of visual and audio information is not suitable for the preservation and acquisition of the skill. This is because the expert skill requires haptic information that is obtained from the real environment. So, in order to realize the preservation and acquisition of the skill, the novel database which is able to store and replay bilateral haptic information as well must be developed. Thus, in this paper, the haptic skill database based on bilateral control that is able to preserve the skill and to replay it is proposed. The experimental results show the viability of the proposed methods

Improvement of operationality for bilateral control based on nominal mass design in disturbance observer

In recent years, although there are many researches on bilateral control, there is little research on improvement of operationality. It will be so effective for operators to improve the operationality of the system in bilateral control. In this paper, a new improving method of operationality which is based on design of nominal mass in disturbance observer is proposed. First, disturbance observer which is implemented in the system is introduced. Then, the relationship between observer gain and nominal mass variation in disturbance observer is discussed. Secondly, bilateral control for transmitting of vivid force sensation is proposed. Then, the proposed method is applied to bilateral control. Finally, the experimental results show the viability of the proposed method.

Bilateral control with different inertia based on modal decomposition

A bilateral control robot is one of the master-slave teleoperation robots. Consider two robots, a master robot is manipulated by human operators and a slave robot contacts remote environment. Decoupling of a force control and a position control in bilateral control is realized using the mode transformation i.e. a force controller in the common mode and a position controller in the differential mode. In conventional method, high transparency in a bilateral control is obtained when the inertia of the master and slave robots are equal. However, high transparency is not achieved when the inertia of the master and slave robots is different. Additionally, transparency goes down in the case of the bilateral control with scaling. Since the common mode and the differential mode interfere when the inertia and scaling of the master robot slave robots are different. In this paper, modal space disturbance observer (MSDOB) is proposed to solve these interferential problems. MSDOB is disturbance observer in the modal space and is implemented in each mode. MSDOB eliminates these interferences and modeling error in the modal space. In the results, decoupling of the force control and the position control is realized. Therefore, high transparency is achieved even if the inertia and the scaling of the master and slave robots are different. From the simulation and experimental results, the validity of the proposed method was confirmed.

A Bilateral Controller Design Method for Master-Slave Robots with Different DOF

In this paper, a bilateral controller for master-slave robots with different DOF (degrees of freedom) is designed based on concept of multilateral control. A multilateral control system is a kind of bilateral control systems, and it is composed of multi-master and multi-slave robots, e.g. two master robots and three slave robots. It is shown that multilateral control, including bilateral control, is realized by using mode transformation by DFT (discrete Fourier transform). In addition, decoupling of each mode and transparency for multilateral control are discussed. Moreover, multilateral control is applied to a bilateral grasping control system. In this system, a human operator manipulates two master robots, and three slave robots grasp an object cooperatively. The proposed system makes it possible to grasp an object tightly in the slave side and to transmit feeling of grasping to a human operator vividly. The validity of the proposed method is shown by the experimental results.