Adaptive control for shape memory alloy actuated systems with applications to human-robot interaction

Enming Shi; Xu Zhong; Tian Wang; Xiaoguang Li; Chunguang Bu; Xingang Zhao

doi:10.3389/fnins.2024.1337580

Adaptive control for shape memory alloy actuated systems with applications to human-robot interaction

Front Neurosci. 2024 Jan 31:18:1337580. doi: 10.3389/fnins.2024.1337580. eCollection 2024.

Authors

Enming Shi^{1

2

3}, Xu Zhong⁴, Tian Wang⁵, Xiaoguang Li⁶, Chunguang Bu^{1

2}, Xingang Zhao^{1

2

3}

Affiliations

¹ State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang, Liaoning, China.
² Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang, Liaoning, China.
³ University of Chinese Academy of Sciences, Beijing, China.
⁴ Medical Engineering Department, Affiliated Hospital of Yangzhou University, Yangzhou, Jiangsu, China.
⁵ The Fourth Affiliated Hospital of China Medical University, Shenyang, China.
⁶ School of Intelligent Manufacturing, Huzhou College, Zhejiang, China.

Abstract

Introduction: Shape memory alloy (SMA) actuators are attractive options for robotic applications due to their salient features. So far, achieving precise control of SMA actuators and applying them to human-robot interaction scenarios remains a challenge.

Methods: This paper proposes a novel approach to deal with the control problem of a SMA actuator. Departing from conventional mechanism models, we attempt to describe this nonlinear plant using a gray-box model, in which only the input current and the output displacement are measured. The control scheme consists of the model parameters updating and the control law calculation. The adaptation algorithm is founded on the multi-innovation concept and incorporates a dead-zone weighted factor, aiming to concurrently reduce computational complexities and enhance robustness properties. The control law is based on a PI controller, the gains of which are designed by the pole assignment technique. Theoretical analysis proves that the closed-loop performance can be ensured under mild conditions.

Results: The experiments are first conducted through the Beckhoff controller. The comparative results suggest that the proposed adaptive PI control strategy exhibits broad applicability, particularly under load variations. Subsequently, the SMA actuator is designed and incorporated into the hand rehabilitation robot. System position tracking experiments and passive rehabilitation training experiments for various gestures are then conducted. The experimental outcomes demonstrate that the hand rehabilitation robot, utilizing the SMA actuator, achieves higher position tracking accuracy and a more stable system under the adaptive control strategy proposed in this paper. Simultaneously, it successfully accommodates hand rehabilitation movements for multiple gestures.

Discussion: The adaptive controller proposed in this paper takes into account both the computational complexity of the model and the accuracy of the control results, Experimental results not only demonstrate the practicality and reliability of the controller but also attest to its potential application in human-machine interaction within the field of neural rehabilitation.

Keywords: SMA actuator; adaptive control; gray-box model; hand rehabilitation robots; robustness.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was partly supported by the National Natural Science Foundation of China under grant numbers U22A2067, 62103406, and 62333007, and also supported by the Applied Basic Research Program Project of Liaoning Province under grant number 2022JH2/101300102, as well as by the Huzhou Science and Technology Project under grant number 2023YZ39 (Corresponding authors: XZ and TW).