Two-axis Measurement System With Large Field Of View Based On Line Structured Light

In order to realize the high-precision and low-cost measurement of the full view of complex medium-and-small-sized object, a two-axis measurement system with large field of view based on line structured light that is mainly composed of a CCD camera, a line structured light generator and two numerical controlled rotary tables is proposed, based on the theory of image processing and machine vision. First of all, the operation principle, coordinate conversion model as well as calibration methodology of the system is intensively studied. Then, the system proves to possess comparatively high precision by the experimental measurement result. The main work accomplished and presented in this thesis can be summarized as follows:1. With the use of existing calibration method for line structured sensor, the mathematical model of the camera, in which the aberration error has been compensated, is built. And the intrinsic-parameter calibration of the system based on CMM and single saw-tooth target is finished.2. The mathematical model is established to transform the 2D data in image plane coordinate system into the 3D data in world coordinate system defined as measured-object-numerical-controlled-rotary-table coordinate.3. The extrinsic-parameter calibration methodology of the system using a single standard ball target is presented. By measuring the ball center at different angles of the numerical controlled rotary tables, some"conjugate pairs"are identified for solving the extrinsic parameters; hence the three coordinates of a point on the laser plane can be computed according to the stripe on CCD image and the rotation angles of two rotary tables.4. A software,through which the calibration and measurement process can be implemented and hardware can be controlled, is developed in Visual C++6.0 development environment on Windows XP platform. And a series of experiments are conducted.The innovation of this thesis lies in the two-axis structure, the 2D to 3D coordinate system transformation model, as well as the extrinsic-parameter calibration methodology using"conjugate pairs".