A Contact Type Three-Dimensional Position Measuring Instrument for Verification of a Piping Inspection Robot

Abstract: Since 1965, the sewerage system development have been promoted in Japan, but as the number of management facilities has increased, the number of facilities that have been used for a long time has also increased, and nowadays, they are too old for daily operation. Because of this problem, the maintenance of drainage and sewer pipes have been carried out continuously. However, in-pipe inspection has a wide inspection range and is a harsh task for operating personnel, which leads to actively-performed inspections using robots in recent years. Under the circumstances mentioned above, the stand-alone type of robot, which can inspect piping by itself, is becoming the mainstream at present. We have focused on the capability of embedding downsized yet high performance PCs and sensors. In recent years, we have been studying and developing robots with those capabilities on board for piping inspection. However, for the inspection using the robot, there is always the risk that the robot itself tips over due to the undulation of the pipe joint and the slip caused by sludge. Therefore, we devised a self-position estimation in absolute coordinates using only an accelerometer in order to achieve highly accurate straight-ahead control for preventing tip over as a software approach without relying on hardware approach such as tire replacement or similar methods. Currently, we are in the stage of verifying this self-position estimation, and for that purpose, we need an instrument for measuring the position of the robot. Therefore, in this paper, we propose the structure of the measuring instrument that does not significantly disturb the driving of the robot due to the disturbance caused via the connection part of the piping inspection robot and the measuring instrument. In addition, as a result of experiments, even in the initial state where the accuracy of the measuring instrument is not calibrated, the average translation error is within 0.58 mm, the average angle error is within 0.12 degree, the standard deviation of the translation error is within 0.86 mm, and the standard deviation of the angle error is within 2.67 degree. It is shown that it can be used for verification of the robot