Abstract

Coordinate measuring machines (CMMs) are one of the most important geometrical measurement devices which are widely used in various industrials. The development of high precision, reliable and high speed trigger probe enables automatic and accurate measurement of freeform surfaces, which leads the trigger probe to be the most widely used probing system in the CMM machines. However, the traditional probing system has its limitations. For example, it can only measure points on a relatively smooth surface. When measuring sharp features (e.g. edges, corners), the probing error is large. Moreover, it is difficult to probe on these features. This paper presents a multi-sensor CMM measurement method for measuring freeform shapes with sharp features, which utilizes the trigger probe to measure the points on the smooth surface while uses the image sensor to measure the sharp features. Experiment was conducted on a multi-sensor CMM machine to demonstrate the effectiveness of the proposed method. The enhancement of the accuracy with the proposed method was also discussed. The result proved that the proposed method can significantly improve accuracy for measurement of the sharp features.