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An Accurately Controlled Antagonistic Shape Memory Alloy Actuator with Self-Sensing
Robotic Laboratory, BeiHang University, HaiDian District, 37 XueYuan Road, Beijing 100191, China
* Author to whom correspondence should be addressed.
Received: 10 April 2012; in revised form: 21 May 2012 / Accepted: 30 May 2012 / Published: 7 June 2012
Abstract: With the progress of miniaturization, shape memory alloy (SMA) actuators exhibit high energy density, self-sensing ability and ease of fabrication, which make them well suited for practical applications. This paper presents a self-sensing controlled actuator drive that was designed using antagonistic pairs of SMA wires. Under a certain pre-strain and duty cycle, the stress between two wires becomes constant. Meanwhile, the strain to resistance curve can minimize the hysteresis gap between the heating and the cooling paths. The curves of both wires are then modeled by fitting polynomials such that the measured resistance can be used directly to determine the difference between the testing values and the target strain. The hysteresis model of strains to duty cycle difference has been used as compensation. Accurate control is demonstrated through step response and sinusoidal tracking. The experimental results show that, under a combination control program, the root-mean-square error can be reduced to 1.093%. The limited bandwidth of the frequency is estimated to be 0.15 Hz. Two sets of instruments with three degrees of freedom are illustrated to show how this type actuator could be potentially implemented.
Keywords: shape memory alloy; self-sensing; hysteresis compensation; instrument
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MDPI and ACS Style
Wang, T.-M.; Shi, Z.-Y.; Liu, D.; Ma, C.; Zhang, Z.-H. An Accurately Controlled Antagonistic Shape Memory Alloy Actuator with Self-Sensing. Sensors 2012, 12, 7682-7700.
Wang T-M, Shi Z-Y, Liu D, Ma C, Zhang Z-H. An Accurately Controlled Antagonistic Shape Memory Alloy Actuator with Self-Sensing. Sensors. 2012; 12(6):7682-7700.
Wang, Tian-Miao; Shi, Zhen-Yun; Liu, Da; Ma, Chen; Zhang, Zhen-Hua. 2012. "An Accurately Controlled Antagonistic Shape Memory Alloy Actuator with Self-Sensing." Sensors 12, no. 6: 7682-7700.