Ken'ichi Koyanagi

High-performance 2-D force display system using MR actuators

A force display system is a kind of human-coexistent robot systems, which share the space with people while they are working, and which directly touch and display force-senses to their users. For such a robot system, it is important to estimate safety quantitatively and to ensure mechanical safety. In this paper, it is described that using MR (magneto-rheological) actuators, which is one clutch type actuators, can ensure safety. Moreover, the characteristics of MR actuators that are low inertia, high torque/inertia ratio and high responsibility contribute to improve the performance of force display systems. In this study, we developed an MR actuator with low inertia (2.6/spl times/10/sup -5/[kg/spl middot/ m/sup 2/]), high torque/inertia ratio (3.8/spl times/10/sup 5/[1/s/sup 2/]) and high responsibility. Torque/inertia ratio of this MR actuator is highest among MR actuators developed so far and much higher than those of conventional servo actuators. Then, a high-performance 2-D force display system using the MR actuator was developed. Maximum force displayed is 190 [N] and rigidity of the system is 5.9 [N/mm]. Moreover, backdrivability, dynamic range and collision sense are improved by using MR actuators in comparison with a system using ER actuators.

Basic Algorithm of Controlling Passive Force Display System with Redundant Brakes

Force information in virtual space is important and often required for tele-operation, training, amusement, design supporting, and other virtual reality systems. While passive force display which uses only passive elements is an effective method for assuring safety, it has some directions and link postures which are hard to present force. To this problem, a method for improvement of controllability using redundant couple of brakes had been suggested. This method was able to make it possible to display various force directions and various postures of virtual objects. The purpose of this study was further improvement of controllability of systems with redundant couple of brakes. In this paper, we discussed the outline of developed redundant-type system and basic experiments with it. We also mentioned an algorithm how to use the brakes to represent various positions and orientations of virtual objects. It was confirmed by experiments in some typical cases.

Development of 3-D Rehabilitation System for Upper Limb-2nd Report: Motion Exercise Training Software for Upper Limb-

Movements of the upper limbs are complicated, various and indispensable for daily activities. It, therefore, is important for the aged to exercise to keep their upper limb function. Also when something is wrong with the upper limb function because of disease or disorder, rehabilitation along with medical treatment is needed to recover function. Application of robotics and virtual reality technology makes possible for new training methods and exercises on upper limb rehabilitation and for quantitative evaluations to enhance the qualitative effect of training. We involved in a project managed by NEDO (New Energy and Industrial Technology Development Organization as a semi-governmental organization under the Ministry of Economy, Trade and Industry, Japan), “Rehabilitation System for the Upper Limbs and Lower Limbs, ”and developed a 3-D exercise machine for upper limb (EMUL) . In this paper, We described softwares to control the moving trajectory of the patients hand by EMUL. They were able to be applied the system to practical rehabilitation training such as passive exercise training, active-assistive exercise training or active exercise training.

Study on force display system using couple of ER brakes

Force information in virtual space is important and often required for tele-operation, training, amusement, design supporting and other virtual reality systems. While conventional force displays are active systems with actuators and therefore may become inherently dangerous, passive force displays, which use only passive elements, are an effective methods for assuring safety. However, passive type systems have some directions and link postures, which are hard to present force. To this problem, a method for improvement of controllability using redundant couple of brakes had been suggested. It was able to be considered this method made it possible to display various force directions and various postures of virtual objects. The purpose of this study was, for further improvement of controllability of systems with redundant couples of brakes, design and development of more generalized redundant mechanism by adding another element of design freedom. Moreover, improvement of force display-ability by reducing equivalent inertia was also aimed. In this paper, the developed system was outlined and basic experiments with it discussed.