Dynamic Modeling and Simulation of a Crocodile-Like Robot

The ability of crocodiles to adapt to complex aquatic and terrestrial environments, such as land and nearshore tidal flats, provides an excellent biological prototype for the design of amphibious robots. In this paper, a 16-degree-of-freedom biomechanical crocodile robot multibody dynamic model is presented within the Lagrangian framework, using centroid coordinates and quaternions to describe rigid body motion, and Coulomb model and non-smooth LCP formulations to describe contact and friction with the ground. A discrete numerical solution is obtained using the linear-time variational integration algorithm, and a simulation study of the locomotion of the crocodile robot on land is conducted. The results of the virtual prototype simulation show that the crocodile robot can achieve stable crawling under the set control torques, verifying the rationality of the biomimetic crocodile robot design. This research lays the foundations for subsequent gait trajectory optimization and control of the crocodile robot.