Three-dimensional hysteresis compensation enhances accuracy of robotic artificial muscles

Smart Materials and Structures, 2018

Jun Zhang, Anthony Simeonov, Michael C Yip

Abstract: Robotic artificial muscles are compliant and can generate straight contractions. They are increasingly popular as driving mechanisms for robotic systems. However, their strain and tension force often vary simultaneously under varying loads and inputs, resulting in three-dimensional hysteretic relationships. The three-dimensional hysteresis in robotic artificial muscles poses difficulties in estimating how they work and how to make them perform designed motions. This study proposes an approach to driving robotic artificial muscles to generate designed motions and forces by modeling and compensating for their three-dimensional hysteresis. The proposed scheme captures the nonlinearity by embedding two hysteresis models. The effectiveness of the model is confirmed by testing three popular robotic artificial muscles. Inverting the proposed model allows us to compensate for the hysteresis among temperature surrogate, contraction length, and tension force of a shape memory alloy (SMA) actuator. Feedforward control of an SMA-actuated robotic bicep is demonstrated. This study can be generalized to other robotic artificial muscles, thus enabling muscle-powered machines to generate desired motions.

Zhang et al. (2018) Three-dimensional hysteresis compensation enhances accuracy of robotic artificial muscles, Smart Materials and Structures, vol. 27, no. 3, pp. 35002.

Pub Link: http://iopscience.iop.org/article/10.1088/1361-665X/aaa690/meta
arXiv: