Objectives   The sewer pipeline network is an essential urban infrastructure. It is easy to be with faults because of the complicated circumstance under the ground, as well as undertaking the transportation and circulation of water. To avoid serious accidents caused by the faults, periodic and systematical inspection devices and methods are necessary. While current methods exist a variety of limitations, especially for large-scale and hard-inspected urban sewer pipe networks. Thus, we proposed a novel collaborative inspection method with high efficiency and availability, and low cost for urban sewer pipe networks.

  Methods  Firstly, we invent a novel device named pipe capsule equipped with video cameras, lights, and a data storage facility. It will be dropped into pipes, move along with water flow, and record the videos of the inner walls until salvaged by the staff from the downstream. Such that, the video is captured to inspect the underground pipe. Multiple capsules are cooperated to complete the inspection task. A collaborative inspection method is designed through well design practice plan by maximizing the inspection range and degree, as well as minimizing the traveling length and time of the workers. Simulated annealing with a simple neighborhood search strategy is used to find the best practice plan.

  Results  Taking the sewer pipe network at Shenzhen University, China an example, an experiment was conducted to verify the performance of the proposed approach. The results demonstrate that the collaborative inspection method achieves the same inspection with a shorter working time.

  Conclusion  This study presented a collaborative inspection approach to detect the large-scale and complicated urban sewer networks with machine vision. It will benefit the inspection and operation of the urban underground pipe network.