SELF-LOCALIZATION METHOD USING ACOUSTIC REFLECTION FOR INSPECTION ROBOT IN UNDERGROUND ENVIRONMENTS

Abstract

 In this paper, we propose a method of self-localization using acoustic reflection to introduce a robot into an indoor civil engineering environment. The acoustic sensor consists of a pair of horizontal omnidirectional loudspeakers and a horizontal omnidirectional microphone. The sound emitted from the loudspeaker is reflected from the wall and reaches the microphone. By measuring this time, the distance of the reflection path to each wall is measured. Using the distance of the reflection path, the rotation speed of the rotary encoder attached to the wheels of the robot, and the pre-supplied map information, we used an extended Kalman filter to estimate the self-position. Simulation verification showed that when the standard deviation of the acoustic sensor was 0.2 m, the positional error was less than 0.1 m. When the robot stage was moved 1 m in an anechoic room, the maximum error in position estimation was found to be ±0.05 m.