The study of tracking control of a robotic manipulator actuated by shape memory alloy

Shape memory alloy (SMA) composites offer a great potential as actuators because of its excellent power to weight ratio, smooth motion and silent actuation. However, SMA actuated robotic manipulator systems have severe hysteresis, system nonlinearities, model and parametric uncertainties those are often responsible for position inaccuracy in a regulation or tracking system. A simple and upstanding control algorithm for tracking control of a SMA actuated robotic manipulator system is presented in this paper. The controller is developed based on the combination of a variable structure control approach and a heuristic based intelligent control approach like fuzzy logic control (FLC), so that the resulting control algorithms have a superior performance both in stabilization and tracking the desired trajectories. A desktop prototype of the robotic manipulator system is recalled from our previous work. A nonlinear form of proportional-integral-derivative (PID) controller is also employed to the system for comparison of performance. Several experiments have been performed in tracking both stationary and periodically varied input signals. Experimental results from real time control verify the effective and robust performance of the controller.