Position control of a single-link mechanism activated by shape memory alloy springs: experimental results

This paper presents the control performance of a novel type of single-link mechanism activated by shape memory alloy (SMA) springs. After briefly describing the configuration of the proposed mechanism, the governing equation of motion is derived using a Lagrangian equation. The actuator dynamic of the SMA spring is then empirically identified and incorporated with the governing equation. A sliding mode controller which is known to be robust to parameter variations is formulated in the error state space in order to achieve the desired end-point position of the single-link mechanism. The controller is experimentally realized and tracking control performances for various end-point position trajectories are presented.