Workspace solution and PID control of 3-DOF parallel mechanism based on Matlab/SimMechanics

This paper deals with the workspace solution and PID control realization of an R-P-S (Revolute-Prismatic-Spherical) joint structural 3-DOF parallel mechanism. Workspace and controllability are two important aspects of parallel mechanisms. This paper analyzes the inverse kinematics of this mechanism and proposes a numerical method of dispersing independent pose variables to determine its workspace in Matlab software under the consideration of inverse kinematics and physical constraints. After a virtual model is established using SimMechanics module from Matlab/Simulink, a PID controller and other modules are designed to make the manipulator reach desired pose. And response of the center of upper platform for a 2cm motion along the z direction is analyzed and result shows that this virtual model could simulate the motion of this mechanism properly.