Motion estimation of snake robots in straight pipes

We present a method of estimating a snake robot´s motion inside and outside of straight pipes using only knowledge of the robot´s joint angles. We accomplish this by introducing a novel method to constructing a body frame for the robot that is aligned with the centerline of the pipe. In addition to greatly simplifying the motion model this method allows us to accurately estimate the diameter of the pipe. We present experimental results using a 16-DOF snake robot traversing the inside and outside of straight pipes.