Structural Design And Modeling Analysis Of Lower Limb Rehabilitation Robot

Rehabilitation robotics,as an alternative solution for patients with functional impairments,has proven to be an effective approach.Compared to manual rehabilitation therapy,rehabilitation robots offer higher movement precision and stronger load-bearing capacity,making them more suitable for high-repetition rehabilitation training.In this study,based on the Stevenson III six-bar linkage synthesis technique,a single motor-driven rehabilitation robot was designed to assist patients in achieving the restoration of a normal gait.The main research work conducted is outlined as follows:(1)Exploring the design of a single degree-of-freedom lower limb rehabilitation robotic leg with a mechanism capable of natural walking motion,utilizing the six-bar linkage synthesis theory.Firstly,an analysis of the human lower limb structure and motion mechanism was performed,leading to the construction of a 3R chain structure.Then,leveraging the mathematical theory of linkage synthesis,250 data points were collected using the Nokov Mars2 H 3D gait analysis system.Subsequently,B-spline fitting and selection were employed to plot the ankle joint’s motion trajectory,based on which a set of feasible design solutions using the Stevenson III six-bar linkage was obtained.(2)The three-dimensional model of the rehabilitation robotic leg was designed using Solid Works software.Furthermore,finite element static analysis of the robotic leg’s structure was conducted using ANSYS-Workbench software.(3)Kinematic and dynamic analyses were performed.The kinematic equations of the rehabilitation robotic leg system were derived using vector loop equations.Kinematic simulations of the leg’s linkages were carried out using Solid Works Motion and MATLAB software to validate the correctness of the kinematic equations.Additionally,dynamic analysis of the designed rehabilitation robotic leg structure was conducted using the Lagrangian method,obtaining the input torque of the driving shaft.(4)To meet the control requirements of the lower limb rehabilitation robot,a control system was designed,and control software was developed.The PID control algorithm was employed,and experiments were conducted on a physical prototype.The results of simulations and experiments were compared to verify the effectiveness of the control system.Simultaneously,it was demonstrated that the designed lower limb rehabilitation robotic leg can meet the requirements of patients undergoing rehabilitation training with a normal human gait.