An advanced NURBS interpolator for mechanical-coupled linear servo systems

This study presents a real-time motion control scheme for the control of mechanical-coupled linear servo systems. The scheme comprises a variable-feedrate non-uniform rational B-spline (NURBS) curve interpolator with an S-curve velocity planning function and a synchronous controller, which are implemented in real-time using a digital signal processor. In the proposed approach, acceleration/deceleration (ACC/DEC) planning on the feedrate command is performed prior to the feedrate interpolation process such that the path command errors caused by conventional schemes in which ACC/DEC planning is executed after feedrate interpolation are eliminated. The effectiveness of the proposed control structure is demonstrated experimentally using a NURBS circle for illustration purposes.