Study on a method of control to improve transparency of a wearable joint for kinesthetic feeling induced by an object

It is considered that kinesthetic feeling induced by the kinetic characteristic of a manipulated object plays an important role for performance of human daily skills. Therefore, if we consider a wearable robot/joint as the robot/joint operated by the daily skills, it is necessary to control the robot/joint so that kinesthetic feeling induced by the kinetic characteristic of an object is directly transmitted to a wearer, without any distortion by the kinetic characteristic of the wearable robot/joint itself. This is the control issue of "kinesthetic transparency". This paper discusses a method of control to improve kinesthetic transparency of a wearable joint. Kinesthetic transparency can be basically improved by active compensation. In order to avoid necessity of offline estimation for unknown kinetic parameters of the joint, this paper formulates a control law which automatically estimates the unknown parameters during operation of the joint. Simulation results demonstrate effectiveness of the method. However, experimental results reveal that accurate compensation of frictional terms is necessary for further improvement.