Speed trajectory tracking of a robotic fish based on iterative learning control approach

In this paper, a novel work is presented, where iterative learning control (ILC) approach is applied to a precise speed control approach for a two-link robotic fish. First, by virtue of the Lagrangian mechanics method, we establish a mathematical model for the two-link carangiform robotic fish, which is highly nonlinear and non-affine in control input. According to the structure of the constructed dynamical model, a P-type iterative learning control (ILC) algorithm is proposed for speed tracking tasks of the robotic fish. The convergence analysis of the proposed controller is derived based on composite energy function (CEF). Moreover, its efficiency is not only illustrated by simulations, but also verified through experimental results. It is shown that ILC is an effective control approach for the motion control of robotic fish because of its model-free property and the simplicity of the algorithm.