A Comparative Study of Model-Based Control Schemes for Contouring Accuracy Improvement of 3PRR Planar Parallel-Kinematics Manipulator

The highly nonlinear coupled dynamics in a parallel-kinematics manipulator typically cannot be simply treated as disturbance. Model-based control schemes are usually used to address this issue. This paper presents the improvement of contouring accuracy of a planar 3PRR parallel-kinematics manipulator by applying two model-based control schemes namely decentralized PID control with centralized computed torque feedforward and centralized inverse dynamics control with feedforward. The simulation shows that both control schemes provide better contouring accuracy than decentralized PID control scheme. Furthermore, it is shown that the decentralized PID control with centralized computed torque feedforward outperforms the centralized inverse dynamics control with feedforward given an accurate dynamic model of the manipulator.