Abstract
Optical fiber cable for the broad bands 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 cable. However, once the optical fiber cable is buried under the ground, it is very difficult to confirm the buried position of the pipe. This research aims to identify easily the buried position of the pipe, using the information of the buried position from the pipe. We use two rotary encoders that have pulleys contacting right and left walls of the buried pipe in order to detect directly the information of the buried position of the pipe. Output of the rotary encoder contacting the wall shows the length of the wall. Average of summation of the outputs of the right and the left rotary encoders shows moving distance of a surveying mechanism of the position surveying system. The curvature of the buried pipe is obtained by difference of the outputs of the right and the left rotary encoders. The position of buried pipe is identified by the moving distance and the curvature 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 curvature in the error of 5.9 mm.
