Inverse hysteresis control for shape memory alloy micro-actuators based flap positioning system

As a strong non-smooth nonlinearity, hysteresis has multivalued and nondifferential characteristics, which make it difficult to mitigate the effects caused by the hysteresis directly. For a shape memory alloy(SMA) micro-actuators based flap positioning system, the existence of hysteresis nonlinearities in the shape memory alloy actuators will degrade the system performance, and limit the positioning precision. Addressing on this task, the motion of the SMA flap positioning system and the characteristics of the hysteresis in the SMA actuators is analyzed. A generalized Prandtl-Ishlinskii model is adopted to estimate the hysteresis in the SMA actuators, and the corresponding hysteresis inverse is utilized as compensation. Considering the compensation error, lag effect and unmodeled measure error, the proposed robust adaptive control approach can stabilize the closed-loop system and ensure the accurate rotation of the flap to the desired angle. The effectiveness of the proposed control approach is demonstrated through simulation examples.