Robust sliding mode position control of a fast response SMA-actuated rotary actuator using temperature and strain feedback

摘要

Shape Memory Alloys (SMAs) have a wide variety of applications due to their interesting property called Shape Memory Effect (SME). When the temperature of SMA changes, its crystal structure is transformed between two major phases and stress and strain are generated. Therefore, SMA can extensively be used in order to produce motion and force as an actuator which requires to be controlled in practice. Convection heat transfer and ambient temperature changes impose unwanted disturbances from the environment because of the dependency of SME to temperature. To deal with this problem, an accurate information about the temperature of the SMA is helpful. For this reason, a novel control approach based on Robust Sliding Mode Control (RSMC) is developed for a fast response SMA-actuated rotary actuator that simultaneously utilizes both the strain and temperature of the SMA as feedback signals. To track the desired rotation command signal with small error and to guarantee the stability of the closed-loop system, both strain and temperature feedbacks are used to generate an appropriate electrical current. The performance of the proposed controller is investigated by two experimental tests under free and forced convection heat transfer. Results clarify that the proposed controller exhibits perfect tracking when the environmental conditions affecting the temperature of SMA are variable and unknown. (C) 2019 Published by Elsevier B.V.