A miniature inspection robot negotiating pipes of widely varying diameter

The purpose of this research is to realize a small robot which can negotiate pipes whose diameter varies widely during the robot's course. A new in-pipe locomotion mechanism named "snaking drive" is proposed in this paper and its potential and fundamental characteristics are shown with experimental data of the prototype model. First, in the sections 2 to 5, the basic traveling characteristics of the snaking drive mechanism are discussed: a theoretical formula of the fundamental characteristics and control algorithm are derived, the motions of the robot are simulated on a PC, and the prototype model was designed, developed, and tested. Next, in the sections 6 and 7, additional control algorithms for the front link are derived. They are necessary for steering at T-branches and L-bends of pipes, and also for camera view stabilization. Their performances are also shown by software simulation and experiments. The prototype robots moved in pipes whose diameter varies between 55 mm to 331 mm with the maximum speed of 22 mm/s. The paper also shows that the prototype negotiates T-branches and L-bends of pipes with inspection capability through a camera mounted on the robot.