Analytical control design for a biomimetic robotic fish

In this paper, the modeling and control of a biomimetic robotic fish is presented. The Anguilliform robotic fish consists of N links and N-1 joints, and the driving forces are the torques applied to the joints. Considering kinematic constraints, Lagrangian formulation is used to obtain the dynamics of the fish model. The computed torque method is applied, which can provide satisfactory tracking responses for fish joints. Since this robotic fish is essentially an underactuated system, the reference trajectories for the orientation of the N links are planned in such a way that, at a neighborhood of the equilibrium point, the tracking task of N links can be achieved by using N - 1 joint torques. A four-link robotic fish is modeled and simulated, and the results validate the effectiveness of the controller and reference planning.