Oscillation reduction scheme for wearable robots employing linear actuators and sensors

While compliance control scheme is done for the wearable robot combined with the linear actuator and sensor on it as intended by the user, oscillations occur due to the joint kinematical mechanism. In this paper, the cause of oscillation on the knee joint is analyzed in detail. Also, it is shown that the moment arm is varied with joint angle, it is confirmed that sensed pressure is changed by the variation. In addition, for canceling the oscillation, torque sensor - using the method to move its force/pressure sensor position from the cylinder to the joint, and a wire-pulley system that adjusts the moment arm with a mechanical impedance compensation are proposed. Finally, simulations and experiments are done for demonstrating oscillation reduction by using the DSME wearable robot.