The Development And Application Of Panoramic 3D Measuring Instrument Based On Grating Projection

3D measuring technique was widely applied in reverse engineering, product testing and other fields, but there were many constraints of the development of the realization of 3D measuring technique and point clouds registration. In this paper, a precise control of the fringe phase shift had been implemented by using the subdivision driving of the step motor, the automatic registration of multi-chip had been realized by using the conversion principle between turntable coordinate system and measurement coordinate system. On the basis of these, the panoramic 3D measuring instrument had been developed.Firstly, the paper analyzed several types of non-contact 3D measurements which are based on different theory and introduced general steps of 3D measurement of structured light. The solution phase theory and general principles of phase modulation had been introduced; the unwrapping theory and the related arithmetic of parcel information haf been analyzed. Furthermore, the overall program had been designed based on fringe projection 3D measuring theory.Secondly, the main hardware modules of the panoramic 3D measuring instrument had been designed in detail according to the overall program. When using C8051F340 as the main control chip, the reset of the control circuit and the level switch module had been designed as focus. In the point of the overall program, the precise control of the fringe phase shift according to the subdivided driving of the stepper motor, and above all, the requirements of the solution phase of the four-step phase shifting can be attained. The turntable's structure had been designed in detail on the principle of panoramic measurement.Thirdly, in order to achieve the effective control of the hardware system, the control system of software had been designed. For example, the system main program, System initialization subroutine, stepping motor driver and CCD control subroutine had been designed on the foundation of the workflow of the panoramic 3D measuring system. And for the purpose of operating easily, the PC software had also been designed for human-computer interaction function. Finally, the transformation matrix between the turntable coordinate system and camera coordinate system had been obtained through the system calibration. The automatic registration of fragmentation point cloud had been achieved by utilizing the conversion operations which is received by inverse matrix of transformation and turntable rotation matrix transformed according the spatial coordinates of point cloud. The reliability of panoramic 3D measuring system and the validity of the automatic registration arithmetic of point cloud had been verified through the measurement of the porcelain vase. The data which gets from the panoramic 3D measuring system can be applied greatly during various engineering fields.