Control of spring actuator and its application to biped robot

This paper presents a control method for spring actuators. A spring actuator consists of a motor, a harmonic drive, springs, and a output rotor. The effectiveness of this system is verified by simulations and experiments. The proposed system realizes smooth torque response like direct drive systems, although the mechanism has less volume than the direct drive systems. Moreover, we show an application of the proposed spring actuators to a biped robot. The robot has the spring actuators in all joints. Polyurethane elastomer is utilized as a torsion spring. The robot is 1.3 m height and 80 kg weight