In-Pipe Robot Position Estimation and Moving Speed Improvement via VOD-PIGs

In this paper, a position estimation method for a variable-outside-diameter pipe-inspection gauge (VOD-PIG) for in-pipe inspection is described, as well as how this method improves the robot’s moving speed. Previous studies have developed in-pipe inspection robots (VOD-PIG) that can perform real-time inspections in environments where radio reception is difficult, such as inside pipes. However, a VOD-PIG location estimation method has not been established to data and the deffective locations found via inspection cannot be identified. Therefore, a PIG location estimation method in piping is required. In this study, a location estimation system for VOD-PIGs in piping was developed based on the pressure response of incoming air. Using this estimation system, the appropriate pressure application time according to the pipe length can be commanded from the position estimation, enabling efficient inspections. Experimental results for in-pipe VOD-PIG position estimation showed that the average error rate between the measured and estimated values was 8.2%. Experiments were also conducted on VOD-PIG movement using the estimation system, and a comparison was made with the movement speed results obtained by the conventional control method. Compared to the conventional control method, the control using the developed estimation system enabled the VOD-PIG to move 2.3 times faster. These results indicate that a position-based inspection system enables efficient VOD-PIG position estimation and inspection.