Design And Analysis Of 3-DOF Underactuated Robot Wrist

As underactuated robot has many advantages such as light weight, low cost and low energy consumption, many researches have been focused on it in recent years with many valuable fruits. Based on the project that key technology of robot moving parts is researched which is a key project of Shanghai Science and Technology Commission, the project that the device of 3-DOF underactuated robot wrist is researched which is a project of the fourth Shanghai University Graduate Innovation Fund, and the Shanghai Key Laboratory project "knowledge-based approach to intelligent machnism design", this paper studys a 3-DOF underactuated robot wrist.Firstly, based on the characteristics of the human wrist's operation, this paper provides three concepts for the 3-DOF underactuated robot wrist. Compared with the other two concepts, the concept with a prototype of spherical parallel manipulators is the best concept for the 3-DOF underactuated robot wrist. The drive way that two branches of the 3-DOF underactuated robot wrist are actuated and the other branch is underactuated is decided. Some key parts of the 3-DOF underactuated robot wrist are designed elementarily.Secondly, based on the D-H method, the coordinates systems of the 3-DOF underactuated robot wrist are built. The kinematics of the 3-DOF underactuated robot wrist is analyzed with the spherical analysis theory, meanwhile, forward and inverse kinematics are calculated. According to the conclusion of the forward and inverse kinematics, the rotation matrixes of the links of the underactuated robot wrist are calculated. According to the Lagrange equation, the dynamic model of the underactuated robot wrist is built, meanwhile, the forward and inverse dynamics are calculated. The dynamic equations of the actuated subsystem and the underatuated subsystem are caculated.Thirdly, the simulation model of 3-DOF underactuated robot wrist is established by ADAMS, and the kinematics and dynamics of the 3-DOF underactuated robot wrist are simulated. The influence of the mechanical friction, drive speed and drive direction on the controllability of the 3-DOF underactuated robot wrist are analyzed respectively. The Simulation results prove that the 3-DOF underactuated robot wrist can be controlled. The kinematics of the 3-DOF underactuated robot wrist is simulated again with MATLAB, which proves the kinematics analysis. According to the Monte Carlo method, the workspace of the 3-DOF underactuated robot wrist is simulaed with MATLAB.Lastly, based on the total differential theory, error model of the 3-DOF underactuated robot wrist is built. The error model is simulated in MATLAB, which proves the error model. The study of error model lays the groundwork for the error synthesis.