This study presents an autonomous inspection system for underground pits using an articulated mobile robot. The underground pit is composed of several rooms surrounded by concrete connected to each other by winding pipes. Based on an action list created in advance and environmental maps, the robot autonomously inspects the underground pit by switching between three actions: planar motion, winding pipe passing motion, and image capturing. In planar motion, the robot moves around the room while avoiding obstacles and crosses ditches through distinctive behaviors, switching the allocation of the grounded/ungrounded wheels. In the winding pipe-passing motion, the target path is autonomously generated based on the parameters of the winding pipe. Laboratory and field tests were conducted to demonstrate the effectiveness of the proposed system.

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