Dynamic Behavior of Pipe Inspection Robot Driven by Fluid Force

This paper discusses the dynamic behavior of a pipe inspection robot driven by fluid force. The robot is composed of an inspection part, insertion roller, floats and cables to connect the floats. The robot receives not only drag force but also lift force through each float implemented in every link unit. Through simulation, we found that according to the shape of the pipe, there exists an optimum fluid velocity which provides the inspection position at the center of the pipe. Such optimum velocity is a function of mechanical impedance existing in the robot itself and the radius of curvature. We show a method which keeps the inspection part parallel to the pipe axis irrespective of the position of the center of the radius of pipe. We also consider the dynamic behavior of the inspection part under various parameters, such as the radius of pipe curvature, mechanical impedance of the robot, and the fluid flow rate.