Mechanism Design And Optimization Of A Horizontal Lower Limb Rehabilitation Robot

Walking is a necessary action for human being's survival and living.So improving gait of patients with cerebral stroke and regaining the ability to walk are the important programs and goals for rehabilitation.In a view of the accurate gait rehabilitation of patients with lower limb paralysis from the early stage of rehabilitation,a novel seriesparallel horizontal lower limb rehabilitation robot which has seven-bar mechanism is designed,this design is based on motor relearning therapy.In this paper,the mechanism design,size optimization and gait planning of the robot are made.Firstly,to achieve the training of the single joint training in the early rehabilitation and gait rehabilitation training throughout the recover time,a gait motion experiment is conducted,then the normal gait parameter of healthy human when walking on ground in normal speed is achieved,and a novel series-parallel horizontal lower limb rehabilitation robot has been put forward to realize the design requirement.The robot has a 2-DOF seven-bar mechanism,and its basic organization is a RRRRP five bar mechanism,and a RR mechanism is concatenated to the connecting rod of five bar mechanism.Only singledriven can realize the gait rehabilitation training and hybrid-driven can realize the training of the single joint training.Secondly,through the kinematic analysis of the robot mechanism,the validity of achieving lower limb gait movement by the robot is proved,and the result shows that: to realize the high coupled movement rule of hip joint and knee joint accurately by the foot driven lower limb rehabilitation robot,the displacement and speed of the ankle must be corresponded with the normal gait data.Based on the working space of the 2R serial mechanism and the dimensional synthesis of four-bar linkage,the optimization constraints of the seven-bar mechanism have been analyzed.To achieve the optimization targets: the error values to be minimum,a new kind of optimization algorithm for fourbar mechanism is designed,which is made of a classical quasi-newton methods coupled with genetic algorithm.Then the performing machine size can be solved.These steps lay the foundation for motion control.Finally,to solve the key technology of gait planning,the motor motions of hip training and gait training are studied respectively,and the laws of the lower limb joint motion under different training patterns are achieved.By analysing the laws of the lower limb joint motion,the result show that the design of lower limb rehabilitation robot can realize hip training in stable and gait training in accurate,which verifies the mechanism satisfying the design requirements.