  Studying snake robot locomotion in a cluttered environment has been a
complicated task because the motion model is discontinuous due to the physical
contact with obstacles, and the contact force cannot be determined solely by
contact positions. We present a unique mathematical model of the robot
interacting with obstacles in which the contact forces are mapped on the basis
of a viscous friction model. Also a motion planning strategy has been
introduced which helps deriving the simplest path that ensures sufficient
number of contacts of the robot with the obstacles required to reach a goal
position. Numerical simulations and experimental results are presented to
validate the theoretical approach.
