Control and Unit Design of Redundant Snake Robots Based on Kinematic Model

Abstract

In this paper, we derive a kinematic model and a control law for snake robots which have wheeled link mechanism. First, we define the redundancy controllable system and derive a condition and a control law for the snake robot that the system becomes redundancy controllable. We find that introduction of links without wheels and of shape controllable points in the snake robot's body makes the system redundancy controllable. Using redundancy, it becomes possible to accomplish both main objective of controlling the position and the posture of the snake robot head, and sub-objectives of the singular configuration avoidance, the obstacle avoidance and other tasks. Next, by introducing the concept of an unit for the system, we find the relation of the numbers of actuators, redundancy and shape controllable points, and propose the system design method of the snake robot. Finally, in order to demonstrate the validity of the proposed controller, simulations have be carried out. From simulation results we find that the crawling motion of the snake robot is natural.