Configuration Design And Experiment Of A Gait Rehabilitation Robot Driven By Cables

In this paper,a cable-driven gait rehabilitation robot is designed for stroke patients with motor impairment.Design and analysis of a gait rehabilitation robot based on cable-driven parallel mechanism under gravity are studied.In order to limit the generation of abnormal gait trajectory points,singularity analysis of a type of cabledriven parallel mechanism with pairwise arrangement is studied.According to the dynamic equations of the cable-driven parallel mechanism and the parallelogram constraint condition of the pairwise cables,the characteristics of two kinds of singular pose of the mechanism are analyzed.In order to ensure that the end-effector has only three translational degrees of freedom(the end-effector does not rotate),the matrix composed of the plane normals of each pair of cables should maintain in full rank.Through the analysis of two cable parallel mechanisms with different end-effectors in plane and space,the singular characteristics of suspended cable parallel mechanisms with redundant actuation are explored and summarized.This conclusion can be used not only for the design of gait rehabilitation robots,but also for the design of cabledriven mechanisms in other fields.Then,the detailed mechanical structure design of the suspended cable-driven gait rehabilitation robot is carried out.The cable is connected to two fixed parts installed on the thigh and shank to assist patients in gait rehabilitation training.The dynamic model of gait rehabilitation robot is established,and two types of cable-driven parallel mechanism configurations are analyzed,namely suspended cable-driven parallel mechanism(under-constrained cable-driven parallel mechanism configuration)and fully constrained cable-driven parallel mechanism configuration.The changes of each cable force when the two types of configurations achieve the same normal gait trajectory are compared.The results show that the suspended cable-driven parallel mechanism has lower cable forces,which can effectively reduce the power of the drive servo-motors and therefore reduce the product cost.Then,the structural parameters of the cable outlet points of the suspended cabledriven parallel mechanism gait rehabilitation robot are optimized.The cable tension values are calculated using the minimum 2 norm condition of cable tensions,and the optional range of structural parameters is calculated.According to the minimum mean square values of cable tensions,the optimal cable point positions are determined,and the configuration and scale design of suspension gravity assisted gait rehabilitation robot are completed.Finally,the experimental control platform of cable-driven gait rehabilitation robot is introduced,including hardware composition,connection mode and effective configuration of hardware parameters.The serial port control program is designed based on Lab VIEW and verified by experiments.The communication principle of the driver based on CANopen protocol is introduced.The hardware connection and parameter configuration of the CANopen control mode are realized by combining with the NI controller,and the normal communication is verified by the program.The research results of this paper are applicable to the field of gait rehabilitation.Combined with the characteristics of cable flexibility,the safety and comfort of patients are fully considered.