A study on turning motion control of a 3-joint fish robot using sliding mode based controllers

The fish robot is a new type of biomimetic underwater robot. Because it moves silently, saves energy, and is flexible in its operation in comparison to other kinds of underwater robot such as ROVs (Remotely Operated Vehicles) or AUVs (Autonomous Underwater Vechicles) or UUV (Unmanned Underwater Vehicle) and etc, the fish robot can be applied to many underwater research projects in recent years. In this paper, a model of 3-joint (4 links) Carangiform fish robot type is presented at initial. Then, the dynamic model of fish robot is developed which is based on Lagrange's method. This dynamic model also includes the heading motion of fish robot which is not covered much in other researches. Then, the Sliding Mode Controller (SMC) and the Fuzzy Sliding Mode Controller (FSMC) are proposed to control the straight motion and turning motion of fish robot. Finally, some numerical simulations are conducted to show the feasibility and the merit of the proposed controllers.