Experimental implementation of distributed flocking algorithm for multiple robotic fish

•A multi-link biomimetic robotic fish is modeled as an extended second-order unicycle.•A flocking algorithm is presented for multiple robotic fish swimming in the water surface.•Considering robotic fish׳s internal and external constraints, simulation results are given.•The flocking algorithm is a practical method to realize coordination control of multiple robotic fish.•The algorithm is still feasible in the presence of field limitations and uncertain disturbances.

This paper presents the experimental implementation of a flocking algorithm for multiple robotic fish governed by extended second-order unicycles. Combing consensus protocols with attraction/repulsion functions, a flocking algorithm is proposed to make the agents asymptotically converge to swim with consistent velocities and approach the equilibrium distances to their neighbors. The LaSalle–Krasovskii invariance principle is applied to verify the stability of the system. Besides numerical simulations, platform simulations involving robotic fish kinematic constraint and control mechanism are shown. An experiment with three robotic fish is implemented to illustrate the effectiveness of the proposed flocking algorithm in the presence of external disturbance and boundary collision.