RF odometry for localization in pipes based on periodic signal fadings

Accurate localization is a problem in environments such as tunnels or pipes due to the hostile conditions, dimensions and the general lack of distinctive visual and/or structural features. Standard indoor localization techniques (e.g. visual SLAM) do not work well in pipelines given the lack of exploitable visual features, while outdoor techniques (GPS in particular) do not work inside metal pipes. In this paper, we present a RF odometry-like method to localize a robot along a pipe. Using a radio-frequency signal transmitter and a receiver, we propose and implement the complete setup in order to obtain periodic received-signal fadings and base a localization system on the periodicity of these fadings. There are two main advantages of the proposed system. First, the sensors are easy to install and can be used with any (ground, aerial) robot. Second, the fadings obtained are periodic, avoiding cumulative errors in localization.