Development of a 3 in Sewer Pipe Inspection Robot with a Wire-driven Parallel Elastic Actuator for Emergency Evacuation

This paper proposes a 3 in in-pipe inspection robot "Xbot 1.1", which combines a wire driven mechanism with parallel elastic elements in a link mechanism and a backdrivable rack-and-pinion mechanism. When the power supply fails in emergency, this robot can automatically (passively) shrink its outer diameter, allowing the manual evacuation by pulling in the tether with human hand. To examine the validity of the mechanism, a prototype of the proposed robot was fabricated and tested on an actual force main. Despite the harsh and slimy environment with sewage, the robot successfully traveled approximately 20 m and took camera images inside 3 in pipe, including one bend with connecting part.