Trajectory Tracking Control and Contouring Performance of Three-Dimensional CNC

A three-axes portal-type computer numerical control (CNC) manipulator is analyzed, in this study. In order to improve the trajectory tracking ability of the manipulator for both linear and circular trajectories different controllers are examined. To compare the effectiveness of different control approaches on the improvement of tracking and contouring performance of the examined three-axes portal-type CNC, proportional-integral-derivative (PID), observer-based PID, and feedforward computed torque (FFCT) control approaches are applied. It is observed that not only overshoot in tracking and contour errors but also transient and steady-state errors are reduced using the proposed FFCT controller. Although computing time increases, the FFCT control method is found as the best solution for the considered cases to improve the trajectory tracking ability of the manipulator for both linear and circular trajectories.