关键词: Compliant robotic fish, Nonlinear continuous model, Fluidic actuator, Assume mode method, Resonant efect

Abstract: Compliant mobile robotics is a developing bioinspired concept of propulsion for locomotion. This paper studies the modeling and analysis of a compliant tail-propelled fish-like robot. This biomimetic design uses a fluid-filled network of channels embedded into the soft body to actuate the compliant tail and generate thrust. This study analyzes the nonlinear dynamics of Fish Tail Fluidic Actuator (FTFA). The fluidic expansion under pressure creates a bending moment in the tail. It is demonstrated that the tail response follows the theoretical formulation extracted from the accurate modeling. In this modeling, tail is assumed as a continuous Euler–Bernoulli beam considering large deflection and nonlinear strain. Then, the implementation of Hamilton's principle and the method of calculation lead to the motion equations. The assumed mode method is used to achieve the mathematical model in the multi-mode system that is more similar to the soft continuous system. We investigate the tendencies of the tail amplitude, swimming speed, and Strouhal number when the input driving frequency changes. The simulation results disclose that high swimming efficiency can be obtained at the multi-order resonances; meanwhile, the compliant fish robot is pushed at the corresponding frequency illustrating nonlinear behavior.

Key words: Compliant robotic fish, Nonlinear continuous model, Fluidic actuator, Assume mode method, Resonant efect