Design and control of a robotic wrist joint actuated by the shape memory alloy actuator

This paper proposes a humanoid wrist joint structure actuated by a new shape memory alloy (SMA) actuator, the stroke and the force of which are 20mm and 12N respectively. A new spindle is proposed to achieve to transform the straight motion of the SMA actuator into the rotation of humanoid wrist joint, and simplify the structure of the wrist joint. Finally a PID controller is applied to control the humanoid wrist joint. In this paper the new SMA actuator solves the limitation of short stroke and small output force of the conventional SMA actuator effectively. The proposed humanoid wrist joint provides a new idea for the SMA as a bionic actuator.