Mechanism Design For A Foot-Plate-Based Lower Limb Rehabilitation Robot

The clinical research shows that the body weight support treadmill training,which is based on the principle of neural plasticity,can promote the recovery of lower limb motor function.However,the high labor intensive,bad repetitiveness and low efficiency limited its application.Robot-assisted gait rehabilitation may be a promising approach.According to the need of the robot-assisted gait rehabilitation,this thesis investigates into the conceptual design and dimensional synthesis of a foot-plate-based lower limb rehabilitation robot,and the coupling simulation of human-machine system.The following works have been accomplished.After analyzing the gait feature,gait cycle,gait event and parameters used to describe the human gait,the gait data of a healthy participant is collected using LUKOtronic motion capture system,and the kinematic model of lower limb is developed.Then,the main function of the major lower limb muscles,the function relationship between muscle force,muscle length and its contraction velocity is described.Combining a 2-DOF crank-slider seven-bar mechanism and a cam mechanism,a novel cam linkage mechanism for gait trajectory generation is proposed.The forward and inverse kinematic model of the mechanism is developed,and a method is proposed for the dimensional synthesis of the mechanism,by which a gait mechanism is synthesized based upon normative gait trajectory.The result shows that,the coupler curve matches well with the gait trajectory,and constant speed motor is sufficient for the control of the mechanism.A novel attitude adjustment mechanism is proposed.The mechanism is composed of a cam linkage mechanism that is serially connected with a parallelogram mechanism.The inverse kinematic model and the method for dimensional synthesis of the mechanism is also studied.The foot posture data is used during the synthesis.Finally,a 1-DOF mechanism for gait rehabilitation considering the foot pose is presented by combing the trajectory generation mechanism and the attitude adjustment mechanism,and the structure design of the robot system is also completed.Based upon the three human-machine coupling model under three different training gait,which are developed using Anybody biomechanical modeling software,the effectiveness of the proposed mechanism is analyzed.And referring to the function of lower limb muscles,the reason leads to the difference in physiological parameters between the robot-assist and normal walking is given,and the effects of gait trajectory and the simplification of the degrees of lower limbs on physiological parameters are discussed.