AUTOMATIC DIGITIZATION OF FREE-FORM CURVE BY COORDINATE MEASURING MACHINES

The digitization of mathematically unknown free-form curves is frequently required. Current industrial practice relies on the experience of an operator to determine the direction of a CMM probe's approaching vector and the number of samples to represent a complex curve. An automatic procedure is proposed to generate recursively the approaching vector direction as well as the sampling rate. Several techniques including a linear prediction, a polynomial prediction, and a spline interpolation method have been presented and compared. Experimental results show that the spline interpolation method provides the best digitization accuracy and requires the least number of sampling points.