提出了一种基于PMP原理的对圆形流水线上工件面形进行在线检测的方法。利用DLP将一环形正弦光栅图投射在圆型流水线上某一区域，使用相移器在物体运动方向的垂直方向上进行相移，实现了圆周运动物体各物点相移一致性，同时由于相移方向与物体移动方向垂直，工件移动不会影响相移量，相移量可以较精确地控制。通过采用参考标记和图像旋转恢复可实现N帧变形条纹图像的像素匹配，从而提取三维物体的截断相位，经过相位展开，得到连续相位，并由相位最后解调出物体的高度信息。通过计算机仿真验证了方法的可行性。该方法具有在线、快速，非接触性等特点。

A new three dimensional(3D)on-line inspecting method for workpiece on the circular pipeline by PMP was proposed. A circular sinusoidal grating pattern was projected onto a special inspecting area of the circular pipeline with DLP.The consistency of the all points of the circumferential movement was realized, when the phase-shifting direction was perpendicular to the object moving direction. Because phase-shifting direction was always perpendicular to the object moving direction, the workpiece movement didn't interfere the phase-shifting. The phase-shifting was accurately controlled by the phase-shifting. Pixel matching of these N patterns was processed by a set of referential symbols with special features. The discrete phase could be calculated by image rotating algorithm. In the pixel-matched patterns and the 3D information could be reconstructed by phase unwrapped. The computer emulation result shows that the method is feasible. This method has the characteristics of on-line, fast, non-contact and so on.