Human-Robot Interaction Force Control of Series Elastic Actuator-Driven Upper Limb Exoskeleton Robot

• Published in: IEEE transactions on industrial electronics (1982) Vol. 72; no. 5; pp. 5093 - 5104
• Main Authors: Sun, Zhongbo, Xu, Changxian, Jin, Long, Pang, Zaixiang, Yu, Junzhi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Closed loops; Dynamics; Exoskeletons; Feedback control; Force; Force control; Gears; Hidden Markov models; Hill-based muscle model; human–robot interaction force control (HRIFC); Injury prevention; Muscles; novel series elastic actuator (NSEA); Performance tests; Real time; Robot control; Robots; Springs; Stability; surface electromyographic; Torque; Torsion springs; Tracking
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2024.3468711

To achieve ideal force control in robots interacting with humans, an accurate and stable actuating system is essential. In this article, a novel series elastic actuator (NSEA) with torsion spring and linear spring is designed to provide pliability and safety for physical human-robot interaction in the upper limb exoskeleton robot (ULER). The Hill-based muscle model predicted human joint torques are utilized to determine the linear spring stiffness of the NSEA that facilitates the ULER to provide the reasonable assistive torque. In addition, a human-robot interaction force control (HRIFC) scheme based on an actuator dynamics model is designed, which enables the NSEA-driven ULER to achieve stability of interactive torque in human-in-charge mode and accurate force tracking in robot-in-charge mode. Theoretical proofs demonstrate the stability of the closed-loop system under the proposed HRIFC scheme. The stability and accuracy of force trajectory tracking for the NSEA-driven ULER are verified through simulations and experiments. The muscle activation of the subjects is obtained, which infers the capability of the NSEA-driven ULER to provide effective assistive forces and maintain normal movement modes. Finally, the torsion spring performance test experiments verify that the NSEA-driven ULER can achieve real-time protection and avoid secondary injuries to the subjects.