Three-dimensional Free-form Surface Profile Of The Cmm Adaptive Assessment Methods Research And Software Development,

CNC Coordinate Measuring Machines (CMM) are necessary measuring devices in the modem manufacturing system. Developing mating softwar ofCMM that is used to measure and evaluate parts of profile With complicated andirregular surface accurately is the one of the important projects in the field ofgeometrical metrology all the time.First, in this paper, from the view of actual application and combined withthe characteristic of CMM, the mathematical model of free-form surface is set upby the interpolating bi-cubic parameter B-spline fitting method. Then the set ofreal points with high precision on measured profile is obtained through the proberadius compensation based on the principle that the trace of the center of the ball-shaped is the offset surface of the surface measured. Finally, after an accuratemethod for calculating the normal distance between a measured point and thetheoretical profile is deduced, an optimum model based on least-square method beset up, and an optimum algorithm is introduced to evaluate the real profile error.Its distinguishing characteristic lies in that the position of measured profile can beadjusted automatically to adapt to an ideal profile by iterative optimization untilprecision can meet our needs during data processing. Otherwise, as a part ofCIMS, CMM need exchanging data With the sofftware of CAD/CAM, so IGESexport interface is developed based on IGES standard. In order to show the wholeinformation of the surface, the 3-dimensional free-form surface is drawing usingthe OpenGL.The above functions have been successfully debugged and results show thatsoftware runs steadily, and that final data is accurate and reliable.