Revisiting hybrid five-bar mechanism: Position domain control application

A hybrid five-bar mechanism is a special parallel mechanism that consists two different types of driving actuators: a uncontrollable constant velocity (CV) motor and a controllable servo motor. The control for such a system is still a challenge because of the coupling behavior between the CV motor and the servomotor through a closed loop mechanism. In this paper, the hybrid five-bar mechanism is revisited with a new solution: position domain control for its ideal application in this hybrid five-bar mechanism. It is the first time to solve the challenge of controlling hybrid five-bar mechanisms. A position domain PD control developed by the authors is applied to control the servomotor that follows the master motion of the CV motor in an active way to eliminate the effect of the CV motor on the contour performance. Simulation results for different contour tracking demonstrate that the position domain control obtained much better contour tracking performances compared to previous developed complicated time domain controller.