Nezha-FX: A Morphing HAUV Designed Based on Balanced Cross-Domain Performance Optimization

As emerging multirotor-type hybrid aerial underwater vehicles capable of both flight and underwater operations, numerous conceptual prototypes have been proposed in recent years. However, existing designs lack a balanced consideration of cross-medium stability, underwater maneuverability, and mode-switching reliability within a single configuration, and there remains no unified evaluation criterion for cross-domain performance. To compensate for the limitations of conventional optimization-based design, this work leverages key constraints identified through experiments and employ a multiobjective optimization approach to achieve a balanced design among these competing requirements. A lightweight and reliable foldable-arm system is further developed to support the implementation of the optimized configuration. In addition, through systematic integration of aerial propulsion bench test data with vehicle design parameters, we develop novel static quantitative metrics (cross-domain thrust margin@50%) to comprehensively assess overall design rationality. Finally, simulation and field tests show that the underwater damping of the final prototype has decreased by 55.2%. Compared with the previous generation, the cross-domain average power consumption is reduced by 68.9%.