A Control-Oriented Model of Underwater Snake Robots

In this paper we consider swimming underwater snake robots that are fully immersed in water and moving in a virtual horizontal plane. The main objective of the paper is to develop a model that is well suited for control design and stability analysis for swimming snake robots. The proposed model is notably less complex than the existing models, while significant parameters such as added mass effects, linear drag forces, torques due to the added mass and linear drag forces, are all taken into account in the modeling. An extensive analysis of a previously proposed complex model of underwater snake robots ([1]) is presented, and from this analysis a set of essential properties that characterize the overall motion of underwater snake robots is derived. The proposed control oriented modeling approach captures these essential properties, resulting in a less complex model that is well suited for control design, and at the same time has the same essential properties as the complex model. A qualitative validation of this is given by simulations that present a comparison of representative parameters of the complex and the control-oriented models for lateral undulation and eel-like motion.