Kinematic Analysis And Simulation Of A Parallel Manipulator For Ankle Rehabilitation

Ankle injuries are one of the most common injuries in orthopaedics clinic. They result in repeated injuries by ankle instability and anchylosis etc. Clinic experiments prove that rehabilitation therapy to the sprained ankle effectively promots functional recovery of ankle joint and prevents future injury. At present, ankle rehabilitation devices used in clinic have less functions and they can't meet all needs of the rehabilitation therapy. Home rehabilitation robots based on parallel robotic mechanisms in process of development are expensive, noise, using inconveniently and not fit for home.Mechanism structure decides characteristic of parallel robotic mechanism. The paper proposes a new 3-RSS/RU rotation-inputting parallel robotic mechanism with a central strut based on the .ankle recover mechanism after analyzing and comparing many kinds of parallel mechanism for sprained ankle rehabilitation therapy. It can rotate in three axes and is applicable to sprained ankle rehabilitation therapy.The paper presents the formulation of the inverse kinematics of the 3-RSS/RU parallel mechanism and analyzes the direct solution. It deduces velocity Jacobian matrix. The moment transfer Jacobian matrix is obtained base on the principle of virtual work and simulated the input and output. Based on the inverse kinematics solution, the paper analyzes sections of the workspace, protracts the 3D bend plane of the workspace, obtains the figure of the workspace, discusses the mechanism's parameter influence to the workspace and gets some conclusions by searching boundary numerical values. The velocity isotropy of the parallel mechanism is investigated by the theory of space model and protracted capability charts. These achievements are beneficial to optimizing design for the future.At last based on the inverse kinematics, the simulation system of kinematics and workspace are developed through the method that combines parametic design with interactive design by MATLAB. The simulation system proves that the 3-RSS/RU parallel mechanism robot is fit to ankle rehabilitation therapy and it is valuable for the simulation system to improve designing efficiency.