Design And Performance Research Of 3-UPUR/RRR Parallel Ankle Rehabilitation Robot

A 3-UPUR/RRR paralel ankle joint rehabilitation robot with adjustable virtual rotation center is proposed in this paper.The strucural design,kinematics,workspace and kinematics performane,trajectory planning and dynamics of the mechanism are emphatically analyzed,The main research of this paper is as follows:First,a brief analysis of the composition and motion characteristics of human ankle joint is male based on medical knowledge,and then a three degrete of freedom parallel ankle rehabilitation device with virtual relation center is proposed.The structure and size parameters of the various components are designed based on ergonomics theory,and then establishing the three-dimensional model of 3-UPUR/RRR mechanism in Solidworks.Secondly,the kinematics model of the parallel ankle joint rehabilitation mechanism is set up,and the kinematics analysis of the mechanism is carried out.Mainly include:the use of screw theoy io analyze the DOF(degree of freedom);to testablisb mechainism inverse solution model by closed loop vector method;using Rodridgues parameter analysis method and NewtonRaphson iterative method to establish the analytical solulions and numerical solution model,and then to verify the correctness of the two positive solutions based on the inverse solution;using the theory of iustantaneous screw to deduce the Jacobian matrix of the mechanism;Based on the inverse;kiawmatics solution,drawing the change curve of the length,speed and acceleration of the driving chain when the mechanism moving platform revolves according to the given rule,which lays the fouidation for further theoretical analysis.Then,based on the inverse solution model,and considering the kinematical constraints of each pair,the workspace is solved by using of numetieal disrcrete search method.The results verify the workspace of mechanism can meet the needs of rehabilitation.Definiting the verify the workspace of mechanism can meet the needs of rehabilitation.Definiting the kinematic performance indicators of the mechanism such as manipulability and dexterity based on the Jacobian matrix.Then the virtual prototype model of the mechanism is established and the inverse kinematics simulation is done in ADAMS.Comparing the simulation results of the ADAMS to the calculation results of the Matlab,the correctness of the kinematics is verified.And next the modified trapezoidal rule is chosen to plan the trajectory of the moving platform,Then the planned trajectories were used to simulate the three movements of the ankle joint in ADAMS.Finally,A inverse dynamics model is established.Then the numerical calculation is carried out in Matlab,and the correctness of the model is verified by ADAMS simulation.When the moving platform turns according to the displacement trajectory with sinusoidal curve transition,the force and power of driving joint changes smoothly and without mutation.It suggests that the design of the mechanism can meet the needs of the actual work.