抄録
Optical fiber cable for high-speed and large-capacity communication is usually covered by plastic pipe and buried under the ground. Then, we are required to grasp its real buried position before digging at the construction or the maintenance in order to prevent from the cutting of the optical fiber. This research aims to identify easily the buried position of the pipe, using the information of the buried position from the pipe. We use four rotary encoders that have pulleys contacting top, bottom, right and left walls of the buried pipe in order to detect directly the information of the buried position of the pipe. It is confirmed that the new position surveying system can identify the buried position of a pipe that is 20 m long and has loose three-dimensional curvature in the error of 39 mm
