Cubic Spline Trajectory Planning and Vibration Suppression of Semiconductor Wafer Transfer Robot Arm

Vibration-free motion in minimal time is desired for industrial robotic applications. Hence, these criteria have to be considered during trajectory planning for a robot arm, wherein polynomial splines are often used for interpolating the trajectory through several via points. Among polynomial splines, the cubic spline is the lowest-degree spline that can provide jerk limitation, a feature that is important for reducing vibration during motion. However, using jerk limitation alone does not eliminate vibration completely and sometimes restricts the performance of industrial robots. This paper proposes an implementation of cubic spline optimization with free via points for reducing motion time, combined with input shaping for suppressing vibration. Experiments are conducted on a semiconductor wafer transfer robot arm to demonstrate the effectiveness of the proposed approach.