Design and Analysis of Compact Rigid-flexible Coupled Waist Rehabilitation Robot

Waist diseases such as lumbar disc herniation are mostly caused by spinal instability. Starting from this pathogenic cause, a new type of waist rehabilitation robot is proposed based on the vertebral curvature theory of traditional Chinese medicine. Firstly, to meet clinical needs of waist rehabilitation, the rigid-flexible coupled structure is adopted, which mainly consists of a flexible curvature fitting mechanism composed of a set of soft actuators and a rigid parallel posture adjustment mechanism based on a 3-PRS parallel mechanism. It can realize the precise adjustment of lumbar curvature. And based on the concept of modularization and miniaturization, the modules are compactly arranged for easy use in family. Secondly, to ensure the smoothness of the fitting curves at the end of the multi-soft actuators, the relationship between the elongation of each soft actuator at different curvatures is calculated. Afterwards, considering the structural characteristics of fiber-embedded pneumatic muscles, the static mathematical model of the soft actuator is established, and the position inverse solution of the 3-PRS parallel mechanism is solved based on the screw theory. Finally, the static characteristics tests of soft actuators and the motion performance experiments of parallel mechanism are conducted. And the rehabilitation performance of the robot is evaluated through the acquisition and analysis of human-machine interaction forces and electromyographic signals. The results show that the waist rehabilitation robot can effectively achieve the predetermined rehabilitation functions. It is a promising waist rehabilitation device with good application prospects. © 2024 Chinese Mechanical Engineering Society. All rights reserved.