  In this paper, we propose a novel strategy for a snake robot to move straight
up a cylindrical surface. Prior works on pole-climbing for a snake robot mainly
utilized a rolling helix gait, and although proven to be efficient, it does not
reassemble movements made by a natural snake. We take inspiration from nature
and seek to imitate the Arboreal Concertina Locomotion (ACL) from real-life
serpents. In order to represent the 3D curves that make up the key motion
patterns of ACL, we establish a set of parametric equations that identify
periodic functions, which produce a sequence of backbone curves. We then build
up the gait equation using the curvature integration method, and finally, we
propose a simple motion estimation strategy using virtual chassis and non-slip
model assumptions. We present experimental results using a 20-DOF snake robot
traversing outside of a straight pipe.
