Chen, Longwen
Flexible Exoskeleton Control Based on Binding Alignment Strategy and Full-arm Coordination Mechanism
Cheng, Chuang, Zhang, Xinglong, Chen, Xieyuanli, Dai, Wei, Chen, Longwen, Zhang, Daoxun, Zhang, Hui, Jiang, Jie, Lu, Huimin
--In rehabilitation, powered, and teleoperation exoskeletons, connecting the human body to the exoskeleton through binding attachments is a common configuration. However, the uncertainty of the tightness and the donning deviation of the binding attachments will affect the flexibility and comfort of the exoskeletons, especially during high-speed movement. T o address this challenge, this paper presents a flexible exoskeleton control approach with binding alignment and full-arm coordination. Firstly, the sources of the force interaction caused by donning offsets are analyzed, based on which the interactive force data is classified into the major, assistant, coordination, and redundant component categories. Then, a binding alignment strategy (BAS) is proposed to reduce the donning disturbances by combining different force data. Furthermore, we propose a full-arm coordination mechanism (FCM) that focuses on two modes of arm movement intent, joint-oriented and target-oriented, to improve the flexible performance of the whole exoskeleton control during high-speed motion. In this method, we propose an algorithm to distinguish the two intentions to resolve the conflict issue of the force component. Finally, a series of experiments covering various aspects of exoskeleton performance (flexibility, adaptability, accuracy, speed, and fatigue) were conducted to demonstrate the benefits of our control framework in our full-arm exoskeleton. Upper limb exoskeletons have various applications in rehabilitation [1], [2], powered assistance [3], teleoperation [4], and other scenarios [5]. In addition to the design of the mechanism and system in upper limb exoskeleton research [6], [2], [7], another crucial research area is the control of exoskeletons [8], [9], [10], [11]. In these fields, the flexibility of the exoskeleton is an important performance (i.e., the force required by users to drive the exoskeleton) that directly affects the user experience and the operational feel. Especially for teleoperation exoskeletons, researchers expect that exoskeleton control can allow users to operate the exoskeleton freely, comfortably, and effortlessly, similar to the natural movement of their arms. In powered assistance and rehabilitation applications, the control objective can also serve as the baseline, which adds assistance or resistance force by adjusting the control gain. Therefore, research into fast and flexible exoskeleton control is particularly important.