Multi-parameter measurement of complex part based on color encoded structured light

In order to realize online, real-time, fast and automatic multiparameter measurement of complex part, the principle on encoded sequence is introduced. The sequence has an important property, named window property. The length of the window is quite small relative to the sequence. When the window slides over the whole sequence, the subsequences in the window can be seen exactly once and they may not be same entirely. So, the index of the subsequence in the whole sequence can be identified uniquely. Then, a vision inspection system based on color encoded multistripe structured light is presented. The system consists of a color encoded projector and a camera. Many structured light planes are projected into three-dimensional space. Every light plane has a kind of color and there are total four kinds of color. The combination of the color is expressed as encoded sequence. Corresponding color stripes are produced in camera when these color light planes intersect with the surface of object. Only the color of a stripe and its neighboring is needed to identify its index in the planes´ group. Especially, in the case that not all the light planes are imaged in camera, the window property of encoded sequence is very important to find out the index of stripes. Furthermore, all the structured light planes can be treated as spatial planes in reference coordinate system of camera. It is well known that there exists unique correspondence between each light plane and the image plane. They can be determined uniquely by a 3×1 orientation vector and a selected spatial reference point. Afterwards, a novel method to calibrate the vision system is described. In virtue of coplanarity constraint, points on every light plane are coplanar with selected spatial points respectively. So, it is easy to set up the mathematical model on multiparameter measurement. At last, experiment is carried out to verify the validity. It shows that precise fixture is not necessary while this inspection system is working and only a single image is needed to realize multiparameter measurement.