Design of high D.O.F. mobile micro robot using electrical resistance control of shape memory alloy

Shape-memory alloy(SMA) is a suitable actuator for a micro mobile robot due to its size and weight. However, length of SMA actuators is known to be nonlinear and hysteretic. We can control SMA´s shape analogously to its electrical resistance. This paper presents a platform to construct high degree of freedom robots with tendons of SMA actuators. We incorporate coil shape SMA as variable length tendons of tendon-driven robots. By controlling electrical resistance of SMA tendons, we can control posture of the robot structure in model-based method. A method to resolve electrical resistance for control from given posture of a high degree of freedom robot by using model of SMA and the robot is proposed. A small electrical system for high D.O.F. robots is also developed. As an application of our system, we show a four-legged robot with 16 D.O.F. joints and 24 SMA tendons.