Design and experiment of a sea-air heterogeneous unmanned collaborative system for rapid inspection tasks at sea.

• In response to the challenge of maintaining stable and accurate relative positioning information for USVs and UAVs in unpredictable maritime weather conditions, this article introduces the UWB positioning system for the inaugural application in measuring the relative position of UAV landing on USVs. It also performs a quantitative analysis of the UWB positioning array's error, taking into account the impact of short deck baseline length and wave swaying, and proposes an adaptive filter solution. • A novel "surfing" roll and pitch stability control method for USV is proposed. This adjustment effectively minimizes the rolling and pitching response of the USV, consequently facilitating the smooth landing of the UAV. Simultaneously, the UAV evaluates its relative speed, position, and heading deviation in relation to the USV, and dynamically adjusts the expected docking control inputs and motion parameters using a fuzzy working condition table. Multiple autonomous landing experiments at sea have demonstrated the UAV's high landing accuracy and stability during the docking phase. • A task allocation method for efficient sea surface inspection using a heterogeneous unmanned system is proposed. Simulation tests of a USV equipped with four UAVs conducting sea surface inspection tasks are conducted in UE4 and Simulink. Within a 2km × 2km sea area, the surrounding inspection operation covers 74 % of the sea area and can be completed within 10 minutes. This method holds reference value for large-scale maritime search missions conducted by heterogeneous unmanned systems operating in sea and air environments. The incorporation of Unmanned Aerial Vehicles (UAVs) into sea surface inspection and complex water navigation tasks performed by Unmanned Surface Vessels (USVs) enhances the operational capabilities and task efficiency of heterogeneous systems. The autonomous docking of USV by UAV at sea serves as a foundational and vital element for facilitating collaborative tasks among unmanned systems. Faced with the problem that the UAV visual positioning USV deck is susceptible to interference from maritime meteorological conditions and the positioning accuracy of GPS is poor, this paper introduces the UWB positioning system and analyzes and solves the error disturbance term of its positioning array under the influence of sea sway for the first time. At the same time, due to the error problem caused by the small baseline of UWB installed on the deck, an adaptive Kalman filter that combines GPS speed information and UWB positioning data is proposed to reduce error. In light of the destabilizing effects resulting from the swaying of the USV deck during UAV docking, this study proposes a USV roll and pitch stability control strategy that incorporates environmental wind and wave data. Additionally, a UAV docking controller utilizing a fuzzy PID approach has been developed to facilitate secure and stable UAV takeoff and docking operations at sea. The effectiveness of the proposed algorithm was verified through sea docking experiments under various working conditions. Finally, in the context of the multi-target maritime inspection mission of heterogeneous unmanned systems, an exploratory improved VRP algorithm is proposed, allowing UAVs to quickly and efficiently complete sea surface inspection operations.The feasibility and operational efficiency of the cooperative mission system are tested through joint simulation using Simulink and UE4 in a high-fidelity environment. This provides a reference solution for future applications of heterogeneous unmanned systems in real maritime environments. [ABSTRACT FROM AUTHOR]