Bionic fish tail design and trajectory tracking control

Bionic fish have received wide attention due to their high mobility, high concealment, and high propulsion efficiency. This paper proposes a new type of bionic fish tail, uses the fish body wave equation and penalty function to optimise its parameters, and then conducts a multimodal motion simulation using Adams to verify the feasibility of the bionic fish tail. Second, to realise the trajectory tracking control of the bionic fish, the central pattern generator (CPG) and the sliding mode controller are combined through the transfer function obtained by experiments and data fitting, and a CPG-based sliding mode controller (SMC-CPG Controller) is proposed and proven to be stable. Finally, simulations and experiments of bionic fish tracking under straight and circular trajectories are performed. The experiments show that under the initial error conditions, the bionic fish can quickly eliminate the position error and the heading angle error under the control of the SMC-CPG controller and track the expected trajectory. The position errors for straight and circular trajectory tracking are 8.62% and 11.5% of the body length, respectively, and the heading angle error during the movement always fluctuates between −40° and 60°. The effectiveness of the proposed SMC-CPG controller and the bionic fish tail is verified through experiments.