Acoustic echo-localization for pipe inspection robots

Robot localization in water and wastewater pipes is essential for path planning and for localization of faults, but the environment makes it challenging. Conventional localization suffers in pipes due to the lack of features and due to accumulating uncertainty caused by the limited perspective of typical sensors. This paper presents the implementation of an acoustic echo based localization method for the pipe environment, using a loudspeaker and microphone positioned on the robot. Echoes are used to detect distant features in the pipe and make direct measurements of the robot's position which do not suffer from accumulated error. Novel estimation of echo class is used to refine the acoustic measurements before they are incorporated into the localization. Finally, the paper presents an investigation into the effectiveness of the method and the robustness of the method to errors in the acoustic measurements.