Comparison of Model-free and Model-based Control Techniques for a Positioning Actuator based on Magnetic Shape Memory Alloys

This paper addresses the control issue of a precise positioning system based on Magnetic Shape Memory Alloys (MSMAs). This family of smart materials exhibits a hysteresis phenomenon that needs to be properly addressed in order to build effective devices. A model-free control scheme is compared with two different model-based approaches which exploit an accurate hysteresis model to perform hysteresis cancellation or feedforward compensation. All the control schemes are based on a PID controller which is automatically tuned by solving a set of Linear Matrix Inequalities (LMIs) able to guarantee a desired exponential rate for the error convergence to zero. Finally, the comparison of model-free and model-based control schemes is performed using an experimental set-up to emphasize both the advantages and disadvantages of the different control strategies.