Series Elastic Actuators for Man-Machine Cooperation

Series Elastic Actuators (SEA) provide good characteristics for man-machine cooperation. Also, zero-torque control becomes possible. The paper presents an example of a series elastic actuator on an active knee ankle foot orthosis (KAFO) to support elderly people. A conventional DC motor with a planetary gearing and cylindrical spring is attached to the knee joint of the orthosis. A state space controller with disturbance observer is used to control the sit-to-stand (STS) movement. It becomes clear, that the slender design of the actuator is useful but for convenient daily activities a smaller SEA is needed. This could be accomplished by using special spring designs produced by the selective laser melting method.