Modeling of swimming posture dynamics for a beaver-like robot

A bionic underwater robot swims to generate its propulsion in water, which in turn directly determines its movement stability. Exploring the relationship between the swimming force and the posture is important. This study aims to analyze and model the swimming posture dynamics of a beaver-like robot. The posture dynamics is decomposed into three parts: leg dynamics, body hydrodynamics, and body posture dynamics. First, the leg dynamic model of the beaver-like robot is established using the rigid-fluid integration method. Then, the overall fluid dynamics of the robot is modeled via numerical calculation methods to obtain the forces of the water on the robot body during swimming. Lastly, the swimming posture dynamic model of the robot is constructed to describe the relationship between the leg movement and body posture. The swimming process of the beaver-like robot with bionic alternating and synchronous trajectory is simulated with ADAMS 2019. The proposed modeling method and the swimming posture dynamic model are verified by comparing the simulation and theoretical calculation results of robot posture, which could be used for the swimming posture control of a bionic underwater robot.