Footstep planning for a six-legged in-pipe robot moving in spatially curved pipes

This paper presents a footstep planning algorithm for a six-legged in-pipe robot moving in spatially curved pipes. The algorithm allows us to generate sequences of points on the pipe's inner surface where the contact pads of the robot should come in contact with the surface. The algorithm uses mapping of the pipe onto a two-dimensional surface with a simpler geometry. The algorithm plans footstep sequences on that two-dimensional surface and then maps them back onto the pipe. It is shown that this procedure can be extended by implementing an obstacle avoidance algorithm formulated as a quadratic program.