Mechanism Design And Research Of A4-DOF Robot With The Parallel Upper Arm

The study of the hybrid robot is very valuable because the hybrid robot has a lot of advantages, for example, simple structure, larger work space, high stiffness and high-precision and so on, which the series robot or the parallel robot can not be able to realize individually. A kind of hybrid robot with the parallel upper arm, which the drive motors of the robot had been all designed on the frame, has been researched in this article. The mechanical arm has small quality and high loading capacity, it has a good market prospect.Firstly, the robot structure has been analyzed and studied, the upper arms of the robot is in parallel form and at the same time in series form with the forearm, which can not only improve the structural rigidity but also enlarge the work space. A pitching wrist mechanism which is depend on a double parallelogram mechanism to transfer force and motion has been designed. Because of the characteristic that the upper arm and forearm motors in different axes, the wrist motor is designed on the frame and coaxial with the upper arm motor. The mechanism has a simple structure and easily to be controlled. It has been proved that the pitching wrist mechanism can improve the bending stiffness of the robot forearm arm by mechanical simulation.Secondly, the kinematics of the robot has been analyzed. A link robot coordinate system has been built with the D-H method and got the transformation matrix between the links of the robot. And then the forward kinematics and inverse kinematics of the robot were analyzed, which can provide the mathematical formula for the solving for the robot’s work space.And then, in order to further investigate the performance of the robot’s movement, analysis and research the robot’s work space by using the analytic method. Firstly solving the rod length and range of motion of each joint robot, and then programming by the Matlab software according to the principles of envelope, and then solving the work space graphics of the robot, and the work space has been Analyzed and researched.Finally, a lightweight prototype,whose arms material is aluminum profiles, is treated as the physical verification object. A dynamic static model is created by taking into account the impact of the force of inertia. And then the changes of mechanical properties of the mechanical parts with load has been obtained by the Ansys software.