Bilateral control using functional electrical stimulation with reaction torque observer

Abstract

This paper describes bilateral control using functional electrical stimulation (FES) with reaction torque observers (RTOB). Bilateral control provides force feedback in teleoperation systems. This technology has many potentials in daily activities. For example, it could allow medical doctors to deliver first aid in remote locations or allow humans to communicate using tactile sensation. However, when controlling bodies, operators generally must wear robot arms. However, wearing robot arm has several disadvantages; for instance operators feel restrained, and it is difficult to create the robot arms with multi degree-of-freedom. To solve these problems, bilateral control using FES has been studied. FES can control human bodies using small pads. However, in conventional studies of bilateral control using FES, the reaction force of the operated subject is not transmitted successfully to the operator. Therefore, we propose a method in which the reaction force of the operated subject is estimated using RTOB. We conducted experiments in which, the elbow joints of five healthy subjects were controlled by a bilateral controller. A force controller controlled the operators, and a position controller controlled the operated humans. The experimental results show that the reaction force of the operated subjects was successfully transmitted to the operators. The operators were able to recognize the position of an obstacle on operated subjects' side. In addition, tracking error was reduced compared to that obtained in past studies using conventional methods.