Design, Fabrication and Control of a New Type of The Omnidirectional Spherical Wrist

In this paper, a new type of spherical wrist is investigated. By using CAD/CAM software, simulation and analysis have been done. So, a new type of mechanism has been fabricated by involute axes in the form of conical gears that can create an unlimited revolution for the wrist without singularity. This wrist has the special ability due to its structure and mechanism to use robots for high precision applications and continuous movements without singularity. According to the drawings, the manufacturing of the model for molding and casting of pieces is carried out and then by machining, the dimensions of the parts are achieved to the standard of drawing. After the assembly, the mechanical work pieces are prepared. The direct and inverse kinematics of the involute angles are obtained for the directions of the wrist. Also, according to the kinematics of the robot, the position of the end-effector is calculated. At first, Matlab software is used to simulate the wrist model and also the experimental test is done for validation. At the end, the PD controller is designed to control the yaw, roll and pitch angles and the changes necessary to improve the wrist control have been applied in the controller and AVR-based microcontrollers. Finally, simulation results are verified through theoretical and experimental test.