Development of a Reconfigurable 7-DOF Upper Limb Rehabilitation Exoskeleton With Gravity Compensation Based on DMP

Abstract

With the development of society, the aging population and the number of stroke patients are increasing year by year. Rehabilitation exoskeletons can help patients carry out rehabilitation training and improve their activities of daily living. First, this paper designs a reconfigurable exoskeleton for upper limb rehabilitation. Second, the working space and singular configuration of the exoskeleton are analyzed. Then, Dynamic Movement Primitives (DMP) and sliding mode control are combined to form a new control strategy. Additionally, by changing the working mode of the gravity compensation device and different control methods, the control experiment of the exoskeleton is carried out. The advantages of sliding mode control under combinational reaching law (CRL-SMC) are verified. The influence of the gravity compensation device on motor driving torque and energy consumption is also analyzed. Finally, experimental results show that compared with sliding mode control under power reaching law (PRL-SMC) and PID control, CRL-SMC has better control performance in single joint trajectory tracking and end trajectory tracking, improving control performance by at least 60%. In the best case, the gravity compensation device can reduce the energy consumption by 81.90% and the maximum motor current by 69.25% of the driving element.