Hybrid sliding mode fuzzy logic-based PI controller design and implementation of shape memory alloy actuator

Abstract

In this paper, a new implementation method is proposed for shape memory alloy (SMA) model which is used to design and control SMA based linear actuator. This implementation method is based on strain-driven approach rather than stress-driven approach found in the literature. This approach removes problems associated with model implementation of SMA actuator such as algebraic loop, coupling between constitutive model and dynamic model of SMA and differentiation of algebraic constitutive equations which leads to loss of controllability. A dynamic system that describe the characteristics of one-way bias force based SMA actuator is simulated using this implementation approach. The simulation results show the accuracy of the proposed controller in both of step change and reference tracking and overcomes the disadvantages of overshooting and steady state error of controllers presented previously, in addition achieve fast response during heating and cooling. Moreover, The advantages of the proposed approaches are: simplified implementation method and high accuracy of position tracking. Next, the hybrid sliding mode fuzzy logic PI controller is proposed to removes the problems of overshooting and steady state error in reference tracking and step changes, and achieve fast response during heating and cooling, which are very important in applications such as robotics.