Position Control of an SMA Actuator Using Sliding Mode Control with Time Delay Estimation

Position Control of an SMA Actuator Using Sliding Mode Control with Time Delay Estimation

  Shape Memory Alloy (SMA) actuators possess hard nonlinearities including backlash-like hysteresis and saturation. These nonlinearities result in steady-state error and limit-cycle problem when conventional controllers such as proportional integral derivative (PID) are used for trajectory control. In this study, sliding mode control with time delay estimation (SMCTE) is proposed and applied to an SMA actuator. SMCTE can help convenient estimation of plant model dynamics through time delay estimation, which is the main concept of time delay control technique. Experiments of SMCTE were carried out with and without a boundary layer, and the performances were compared against other controllers.