Flexible Joint Actuator for Patient´s Rehabilitation Device

Rehabilitation devices require a very precise actuating system. In this paper, a flexible joint actuator is proposed as an actuating system of an intelligent active orthosis. To generate joint torque as desired, a spring is installed between a motor and human joint and the motor is controlled to have a proper spring deflection for torque control. When the desired torque is zero, the motor should follow human joint motion which requires that the friction and inertia of the motor are compensated. The human joint and body part represent the load to the flexible joint actuator. They interact with environment and their parameters are not fixed. The controller for the flexible joint actuator must operate under these conditions.