Development of a multi-resolution measurement system based on light sectioning method

Abstract

With the rapid development of shape measurement technique, multi-resolution approach becomes one of valid way to enhance the accuracy. There are, however, still some key techniques such as simultaneous calibration and data fusion of several sensors being further studied. A multi-resolution system, which use light sectioning method, is developed and has been successful in many application areas for blade of aviation engine example. It can measure the shape of blade at high speed and high accuracy. The system is composed of four laser linear light sources, four or five cameras and three highprecision mechanical movement devices. Two cameras have relatively low amplifying ratios, and focus on the basin or back of blade where the radius of curvature is large. Other cameras have high amplifying ratios, and fix on the entering or ending edge of blade where the radius of curvature is small. So the system has 3600 measurement range and can carry out multi-resolution 3-D shape measurement with greatly different amplifying ratios of cameras. One measurement process has been finished when the blade mounted on mechanical movement device move up or down one time. Also the model building and principle of the measurement system, an algorithm of calibration and data fusion of several cameras are presented that calculate 3-D coordinates of one section of blade. The result shows that the accuracy of the system is about 0.05mm for the sectional circumradius approximately 50 mm measurement range, and also proves the system is feasible and efficient.