Localization Techniques for In-pipe Robots in Water Distribution Systems

In water distribution systems, in-line robots are designed to continuously access pipelines for water quality monitoring, leak detection, and visual inspection. However, these robots suffer from limits in the aspects of power supply, under-ground wireless communication, mechanism flexibility, actuator architecture, and control algorithms. In this paper, we propose an end-to-end methodology that lists the requirements and procedures to design and fabricate a new in-line robot with more capabilities. Wireless communication between a base station (BS) and the robot operating underground has been a challenge in the field of underground robot monitoring. We propose two solutions to address the shortcomings of underground wireless communication. In the first scenario, "two parallel robots" that communicate based on Magnetic Induction (MI) communication are presented. We simulate the proposed MI communication link based on a real operating condition. The simulation result shows the received signal power can be detected with a lock-in amplifier for a 1.4 m distance between primary and secondary coils. Also, we propose another wireless communication solution based on Radio Frequency Identification (RFID) with a 13.56 MHz carrier frequency and based on the ISO15693 standard. The mechanism of the RFID based wireless communication works is explained via an experimental setup. The experiment shows that the proposed setup can penetrate the harsh and dynamic environment of water. Also, the read range was measured around 10 cm, which is a safe range to avoid overlap for the nearby readers that might lead to confusion for the robot.