Control an SMA-actuated rotary actuator by fractional order PID controller

The purpose of this paper is to design an appropriate controller for a rotary actuator actuated by Shape Memory Alloy (SMA) wires. The actuator is designed in such a way to be able to rotate in both clockwise and counterclockwise directions using a pair of SMA wires installed on it. The SMA wire is modeled by the Brinson model. Also dynamic and kinematic models of the system are considered in simulation. The convection coefficient of heat transfer equation is resulted from simulating the model and identifying input-output data of the system. According to the nonlinear behavior of the system and due to the nonlinearity of the SMA wires, a Fractional Order PID (FOPID) as a nonlinear controller is designed. The simulation results of trajectory tracking control for a reference input is compared with ones of a traditional PID controller. The better performance of the FOIPD controller with respect to PID controller is stablished.