Control system based on pressure distribution for wearable assist robot on multi-joint body part

Abstract

Wearable assist robots deliver power in form of direct contacts with the user, therefore, safety control is considered to be the prior requirement for wearable assist robots. To improve safety, the robot needs to be controlled based on the current contact state feedback. As a state estimation concept approach, a feedback control system based on joint torque has been proposed. The principle of this approach is that the physical contact forces appear as a certain change in measured joint torque. However, as the joint torque is the resultant of contact forces, the case of user is in danger contact state may not be detected. In this paper, a new control system based on pressure distribution is proposed. Utilizing the pressure sensors directly mounted on the robot's link surface, the robot is controlled to suppress excessive contact forces. On computer simulations, the proposed system was confirmed to be effective to improve safety.