基于位置传感器的微细管道内表面无损检测

Non-Contact Inspection Based on Laser-PSD for the Inner Surface of Small-Diameter Pipes

基于位置传感器(PSD)的特性,提出了一种长距离曲线型微细管道内表面形貌无损检测技术,开发了相应的管道内表面形貌检测器.激光束经过2次反射后,在管道内壁上形成细小的光斑.该光斑被二维PSD接收,产生4路电流信号.根据这些信号和检测器的结构参数,可以计算出对应光斑在局部三维坐标中的位置.反射镜在微型马达带动下旋转1周,使激光束完成1个管道截面环的扫描,从而得到该截面上所有采样点的相对坐标.最后对测量数据进行分割、拟合等处理,重构出截面环的形状,得到该截面处的管道半径以及缺陷情况.在微型管道机器人的带动下,可以对整条管道进行检测和三维重构.根据该技术开发的检测系统,可以实现内径在9.5～10.5 mm、曲率半径大于100 mm的曲线型长距离微细管道内表面的检测,对管道内壁缺陷的测量精度达到±0.1 mm.

A new non-contact inspection technique based on laser and position sensitive detector（PSD） to inspect the inner surface of mini-diameter pipe is proposed,and the corresponding sensor has been developed. A light spot is projected onto the pipe inner wall after the laser beam being reflected by two mirrors. Four channels signal is produced when the light pot is read by the two-dimensional PSD. According to the signals and the structure parameters of the sensor,the spot position on the wall can be calculated in the local 3-D coordinate system. With a micro-motor, the laser beam scans a whole section ring of the pipe inner wall. So the coordinates of all the sample points in the section are obtained. Then, several reasonable data processing methods are deployed, such as data segmentation, least square fitting and so on. Finally, the section curve can be reconstructed, the radius of the section and the defect of the section can be obtained. Driven by a micro-pipe robot, the sensor can inspect a long curved pipe. The inspection system based on the technique can detect the mini-diameter pipe whose inner diameter is 9.5～10.5 mm,and curvature radius is larger than 100 mm. The measurement accuracy of the inner surface defect is ±0. 1 mm.