The Study Of Probe Compensation And Surface Mathing On CMM

Workpieces with free-form curves and surfaces are widely used in space flight,automobile, die and mould industry. The effective accurate inspecting method hasgreat effect on the quality of production in those industries. Especially the inspectionway of die and mould surface shape has become the focus of many scholars'attentions. Presently, the general automatic measuring method and data processingtechnology of free-form curve and surface are being studied both at home and abroad.This dissertation addresses a practical data processing method of free-formsurface for the coordinate measuring machine (CMM), including fitting algorithm,probe radius compensation and surface matching .In this paper, topics on how to measure high accurate free-from curves andsurfaces automatically with CNC-CMM and how to process the measuring data havebeen discussed in detail. The following achievements have been gained: measuring principle of the CNC-CMM were comprehensively introduced. The mathematics model was established for the discrete data of free-formcurve and surface, based on non-uniform B-splines and least square fitting algorithm. Based on non-uniform B-splines, a new algorithm of calculating the normalvector at random position was deduced, and a formula with probe radius correctionwas proposed. An optimization algorithm named simplex method was applied in order toeliminating the orientation error in the stage of workpiece measurement. It can settlesurfaces matching well. An effective program with free-form curve and surface fitting, probe compensation and surface matching,...