Loop forming snake-like robot ACM-R7 and its Serpenoid Oval control

Abstract

This paper discusses the design of a new snake-like robot without wheels, named ACM-R7. It has 18 DOFs, is 1.6 m in length and weighs 11.7 kg. It features a water-tight structure, a large motion range pitch joint of ±90 degree and a high output-power actuator arrangement, based on the coupled drive concept. Furthermore the control method “Loop Gait” is discussed. For this gait the ACM-R7 forms a loop shape and rolls like a wheel on the rim. We introduce the “Serpenoid Oval” for the loop shape. It s formed by a smooth sinusoidal angular motion of the joints. Moreover we consider the modification of the “Serpenoid Oval” for steering and obstacle avoidance. The performance is then verified by several motion experiments.