A Quintic Spline Interpolator for Motion Command Generation of Computer-Controlled Machines

Abstract

This paper presents a new method of motion command generation for computer controlled multi-axis machines. The method is based on a quintic spline interpolator (QSI) which generates motion commands to trace a set of desired discrete position data via a composite quintic spline (CQS). This CQS is nearly arc length parametrized and has second order continuous at the data points. Consequently, the generated motion trajectories are continuous in both velocity and acceleration throughout the motion. A quick motion command generation scheme is also developed. Compared to the existing linear interpolator (LI), the proposed method takes comparable execution time, but is superior in many other aspects, including position accuracy, speed smoothness, acceleration continuity, torque requirement, and jerk reduction. Compared to the existing cubic spline interpolator (CSI), the proposed method is able to maintain a similarly smooth composite profile, but better speed accuracy. On-line implementation of this interpolator is believed very promising.