On acceleration/deceleration before interpolation for CNC motion control

To prevent from path command errors in CNC's motion control, performing "acceleration/deceleration before interpolation" (ADBI) motion planning on the desired feedrate profile is necessary. Although there are a few existing algorithms available for implementing ADBI, there is no clear choice in terms of contour error and machining efficiency. In this paper, a hybrid approach that takes both the contour error and the machining efficiency into account is proposed. In addition, based on the idea of "multi-blocks look ahead", this study also explores the problem of combining ADBI with NURBS (non-uniform rational B-spline) interpolation. A contour that consists of four blocks of NURBS curves is used to compare the performances of three different multi-blocks look ahead approaches: conventional, direct digital convolution, and the proposed hybrid approach. Experimental results show that the proposed hybrid approach exhibits superior performances compared with the other two approaches.