Modelling, simulation and experimental study of a rigid–flexible coupled eel-like robot

Aiming at the problems of weak environmental adaptability, poor flexibility, and low propulsion efficiency of existing bionic robotic fish, this paper proposes a rigid-flexible coupling eel-like robot. Based on the morphology and propulsion mechanism of eels, kinematic and dynamic models are constructed. Dynamic mesh technology and User-Defined Functions (UDF) are used to carry out undulatory drive simulations, analyzing the influence of parameters such as amplitude, frequency, and wavelength on the flow field and propulsion performance. The results indicate that the propulsion force originates from the pressure difference between the two sides of the body, and changing the incoming flow direction can significantly affect the tail vortex morphology and drag components. Through underwater experiments, the propulsion performance of the robot during undulatory swimming is analyzed. Experimental results show that reasonably matching body wave parameters can enhance propulsion capability and directional stability. This research provides theoretical reference and technical support for highly environmentally adaptable underwater robots to achieve efficient, low-noise bionic propulsion in confined spaces and unsteady hydrodynamic regime scenarios.