Research on Unmanned Surface Vehicle Formation and Maintenance Control Based on Improved Extended State Observer

This paper presents a novel fixed-time extended state observer-based control approach for forming and maintaining formations of multi-Unmanned Surface Vehicles (multi-USVs) in the presence of frequent ocean environmental disturbances and uncertain model parameters. Firstly, a simplified three-degree-of-freedom kinematic and dynamic model is established for the USVs. This model allows us to transform the formation control problem into a consensus control problem, aiming to achieve coherence among the formation errors within the system. Furthermore, a potential function is devised to address the issue of inter-vehicle collision avoidance, thereby significantly enhancing safety during both formation and maintenance processes. Moreover, a control strategy based on integral sliding mode is designed to minimize chattering phenomena in the control process. This ensures that the multi-USVs system can precisely establish and sustain the desired formation. Simultaneously, an improved fal-function-based fixed-time extended state observer is adopted to handle unknown disturbances caused by wind, waves, and currents during the formation maintenance. This enhanced observer not only accelerates convergence speed but also reduces the total estimation error compared to traditional observers. Finally, the Lyapunov stability is utilized to demonstrate the asymptotic stability of the entire control system.