Efficient Cooperative Structured Control for a Multijoint Biomimetic Robotic Fish

Abstract

In this article, we propose an efficient locomotion control method for a two-dimensional tracking task of a biomimetic four-joint robotic fish. Regarding this issue as a comprehensive optimization procedure, we propose an optimization-based cooperative structured control framework, in which the combination of evolutionary strategy and deep deterministic policy gradient is employed to optimize the same objective function. An inconsistent optimization method is presented to further enhance the effect of parameter optimization on central pattern generator model. Moreover, for the sake of a higher reward and better robustness of controllers governed by deep reinforcement learning, we propose a linear weighted controller trained with periodic method. Extensive simulation and experimental results verify the significant energy saving of the proposed method in tracking tasks. Noticeably, the cooperative structured control can save <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{23.97}\%$</tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{22.13}\%$</tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{38.72}\%$</tex-math></inline-formula> energy compared with sliding mode control, active disturbance rejection control, and proportional-integral-differential control in experiments, respectively, holding a great promise for the long-term intelligent work of the biomimetic robotic fish in complex aquatic environments.