Hysteresis modeling and position control of actuator with magnetic shape memory alloy

This paper is focused on magnetic shape memory alloys (MSMAs), used for precise movement generation. MSMAs belongs to group of so-called smart materials, which change their properties under external stimulus. Transducers with these materials are alternative designs for classical solutions, where movement is generated by electromagnetic force. Especially in the most advanced mechatronic devices e.g. in bioengineering, aerospace engineering, CNC machines, unconventional actuators can significantly improve their operating parameters. Magnetic shape memory alloys combine good dynamics, similar to magnetostrictive materials such as terfenol D, and deformations range similar to thermally activated SMAs. These properties make it suitable for positioning systems, but before engineering applications it should be well tested. The biggest disadvantage of MSMAs is wide, asymmetric, saturated hysteresis curve. Reason for that is internal friction located on twin boundaries in crystal lattice. These non-linearities have negative influence on control quality in open and closed loop control systems. It can be limited by compensation based on hysteresis modeling techniques. In this paper authors adapted generalized Prandtl-Ishlinskii model (GPIM) and its analytical inversion. GPIM is phenomenological model where hysteresis can be expressed as a sum of weighted play operators. Paper is summarized by results of experimental investigations, where authors made comparison between classical control system with PID regulator and the same control system supported by cascade hysteresis compensation.