Kinematic modeling framework for biomimetic undulatory fin motion based on coupled nonlinear oscillators

The present work is motivated by the need to develop a generic method modeling the biomimetic undulatory motion for fish robots with long fin propulsors. Combined with mechanical design of long fins proposed in current literatures, we explore the application of coupled nonlinear oscillators in the modeling of swimming gaits and propose a kinematic modeling framework. Coupled nonlinear oscillators can also be regarded as models of artificial Central Pattern Generators (CPGs) for swimming gait control of fish robots. The advantages of this method over the normal sinusoidal functions based method are discussed. The synchronization of multiple oscillators is derived, which can be utilized for the coordination of multiple joints of fish robots and the online gait transition. The framework is applied and tested in swimming motion control of an eight-DOF undulatory fin prototype. The effectiveness of the control is shown through experiments.