Robust adaptive control for flap positioning system with SMA actuators-inverse Duhem model-based approach

Abstract

Shape memory alloy (SMA) actuators are a class of smart materials-based actuators, which have some excellent features such as high power-to-weight ratio, large recovery strain and low driving voltages, etc. However, the saturated-type hysteresis non-linearities existing in the SMA actuators will degrade the system performance, and limit the improvement of the positioning precision. Focusing on this task, a robust adaptive control approach for the flap positioning system based on shape memory alloy actuators is addressed in this paper. A differential equation-based hysteresis model, Duhem model, is adopted to describe the saturation and minor loops characteristics in the SMA actuators by choosing the proper slope functions. The inverse of estimated Duhem hysteresis is preceded as the compensation. In this paper, the compensation error, lag effect and the unmodelled measure error are considered, and the proposed control method can stabilise the closed-loop system and ensure the accurate rotation of the flap to the desired angle. Simulations performed on a flap positioning system illustrate and clarify the approach.