Bio-Inspired Cable-Driven Actuation System for Wearable Robotic Devices: Design, Control and Characterization

Wearable robotic devices interact with humans by applying the assistive force in parallel with muscle–tendon sys- tems. Designing actuations in mimicking the natural activation patterns of human muscles is a promising way to optimize the performance of wearable robots. In this article, we propose a bioinspired cable-driven actuation system capable of providing anisometric contractions (including concentric and eccentric con- traction) assistance or nearly acting as a transparent device in an efficient manner. A novel clutch–spring mechanism is employed to accomplish switches between assistive modes and the transparent mode. Corresponding control strategies coordinating with the me- chanical design were presented and described in detail. Multiple evaluations were conducted on a test bench to characterize the system’s performance. The closed-loop bandwidth of the system running concentric assistance control was 18.2 Hz. The R-squared values of linear fitting under eccentric assistance control were above 0.99. The engagement time of the proposed clutch was about 90 ms. Applying the actuation to an ankle exoskeleton, multiple walking experiments with electromyography measurements were Manuscript received 8 July 2023; accepted 2 October 2023. Date of publica- tion 16 October 2023; date of current version 15 December 2023. This paper was recommended for publication by Associate Editor S. Crea and Editor A. Menciassiuponevaluationofthereviewers’comments.Thisworkwassupported by the National Natural Science Foundation of China under Grant 52005011, Grant 52375001, and Grant 91948302. (Ming Xu and Zhihao Zhou contributed equally to this work.) (Corresponding author: Qining Wang.) This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the Local Ethics Committee of Peking University, China, under Application 2018-06-02. Ming Xu, Zezheng Wang, and Jingeng Mai are with the Department of AdvancedManufacturingandRobotics,CollegeofEngineering,andtheInstitute for Artificial Intelligence, Peking University, Beijing 100871, China, and also with the Beijing Engineering Research Center of Intelligent Rehabilitation Engineering, Beijing 100871, China (e-mail: xuming@stu.pku.edu.cn; zezheng- wang@stu.pku.edu.cn; jingengmai@pku.edu.cn). Zhihao Zhou is with the Institute for Artificial Intelligence, Peking University, Beijing 100871, China, and also with the Beijing Engineering Research Cen- ter of Intelligent Rehabilitation Engineering, Beijing 100871, China (e-mail: zhouzhihao@pku.edu.cn). Lecheng Ruan is with the National Key Laboratory of General Artificial In- telligence, Beijing Institute for General Artificial Intelligence (BIGAI), Beijing 100080, China (e-mail: ruanlecheng@bigai.ai). Qining Wang is with the Department of Advanced Manufacturing and Robotics, College of Engineering, and the Institute for Artificial Intelligence, Peking University, Beijing 100871, China, also with the Peking University Third Hospital, Beijing 100191, China, also with the University of Health and Rehabilitation Sciences, Qingdao 266071, China, and also with the Beijing Institute for General Artificial Intelligence, Beijing 100080, China (e-mail: qiningwang@pku.edu.cn). This article has supplementary material provided by the au- thors and color versions of one or more figures available at https://doi.org/10.1109/TRO.2023.3324200. Digital Object Identifier 10.1109/TRO.2023.3324200 performed on five subjects to show its application potential in existing wearable robots. Experimental results revealed that the proposed design could reduce soleus muscle activity by 27.32% compared with normal walking. This study highlights the im- portance of functional bionic design in human-assistance-related devices and introduces a general actuation system that could be directly applied to existing cable-driven wearable robots.