Super twisting sliding mode control of a robotic manipulator actuated by shape memory alloy: Design and experiment

This paper implements a robust control strategy for a robotic arm actuated with shape memory alloy (SMA). The complexity of mathematical models of SMA, arising from the hysteresis behavior, adds complexity to designing a suitable model-based controller. For this reason, a second-order model is utilized to design the position controller. This reduced-order model contains uncertainties arising from the disparity with the actual system. Consequently, the super-twisting sliding mode control (ST-SMC) is implemented due to its capability in handling uncertainty, reducing chattering phenomena, and ensuring high tracking accuracy. Simulation and experimental results demonstrate that the ST-SMC approach has a high performance in handling uncertainties, leading to a high accuracy in tracking time-varying trajectories. Furthermore, in comparison with sliding mode control (SMC), the proposed control exhibits superior performance.