Command Generation For Contouring Motion Control

Recently, modern manufacturing systems can machine arbitrary parametric curveswhile greatly reducing data communication between CAD/CAM and CNC systems.But a constant feedrate between two interpolated points along parametric curves arestill used and it is difficult to achieve chord accuracy. Because of the shape of theparametric curve and the hardware limitation of the systems, an interpolation whichinvolves feedrate should be studied.An adaptive-feedrate interpolation for parametric curves with a confined chord errorand acceleration/deceleration limitation is proposed in this paper. Because the chorderror in interpolation depends on the curve speed and the radius of curvature, and theacceleration/deceleration must be under the admission of the system limitation, thefeedrate in the proposed algorithm is automatically adjusted so that a specified limiton the chord error is met. The feasibility and precision of the proposed interpolationalgorithm is verified by simulation and experiment for non-uniform rational B-spline(NURBS) examples.