Compared to detection methods employed by Mars rovers and orbiters, the employment of Mars UAVs presents clear advantages. However, the unique atmospheric conditions on Mars pose significant challenges to the design and operation of such UAVs. One of the primary difficulties lies in the impact of the planet’s low air density on the aerodynamic performance of the UAV’s rotor system. In order to determine the aerodynamic characteristics of the rotor system in the Martian atmospheric environment, a rotor system suitable for the Martian environment was designed under the premise of fully considering the special atmospheric environment of Mars, and the aerodynamic characteristics of the rotor system in the compressible and ultra-low Reynolds number environment were numerically simulated by means of a numerical calculation method. Additionally, a bench experiment was conducted in a vacuum chamber simulating the Martian atmospheric environment, and the aerodynamic characteristics of the UAV rotor system in the Martian environment were analyzed by combining theory and experiments. The feasibility of the rotor system applied to the Martian atmospheric environment was verified, and the first generation of Mars unmanned helicopters was developed and validated via hovering experiments, which thereby yielded crucial data support for the design of subsequent Mars UAV models.

The precise regulation of the hinge moment and pitch angle driven by the pitch-regulated mechanism is crucial for modulating thrust requirements and ensuring stable attitude control in Martian coaxial rotorcraft. Nonetheless, the aerodynamic hinge moment in rotorcraft presents time-dependent dynamic properties, posing significant challenges for accurate measurement and assessment for such characteristics. In this study, we delve into the detailed aerodynamic hinge moment characteristics associated with the pitch-regulated mechanism of Mars rotorcraft under a spectrum of control strategies. A robust computational fluid dynamics model was developed to simulate the rotor’s aerodynamic loads, accompanied by a quantitative hinge moment characterization that takes into account the effects of varying rotor speeds and pitch angles. Our investigation yielded a thorough understanding of the interplay between aerodynamic load behavior and rotor surface pressure distributions, leading to the creation of an empirical mapping model for hinge moments. To validate our findings, we engineered a specialized test apparatus capable of measuring the hinge moments of the pitch-regulated mechanism, facilitating empirical assessments under replicated atmospheric conditions of both Earth and Mars. The result indicates aerodynamic hinge moments depend nonlinearly on rotational speed, peaking at a 0° pitch angle and showing minimal sensitivity to pitch under 0°. Above 0°, hinge moments decrease, reaching a minimum at 15° before rising again. Simulation and experimental comparisons demonstrate that under Earth conditions, the aerodynamic performance and hinge moment errors are within 8.54% and 24.90%, respectively. For Mars conditions, errors remain below 11.62%, proving the CFD model’s reliability. This supports its application in the design and optimization of Mars rotorcraft systems, enhancing their flight control through the accurate prediction of aerodynamic hinge moments across various pitch angles and speeds.

This study investigates the impact of rotor spacing on the aerodynamic performance of a coaxialcopter and promotes an innovative regulated control strategy for the coaxial drone. The present research introduces a coaxialcopter with variable rotor spacing, and employing finite element numerical simulations, we assess the aerodynamic behavior of this novel configuration. Through comprehensive measurements and analysis of its aerodynamic performance across varying rotor spacings from 0.1 R to 1 R, we validate the effectiveness of a rotor-spacing control strategy for enhancing takeoff maneuvers. The numerical simulation and experiment results reveal that the performance characteristics of both the upper and lower rotors converge toward that of a single rotor as the space ratio increases, along with a reduction in their thrust fluctuations and aerodynamic performance periodicity. Considering stable power consumption patterns and endurance performance, we analyzed the interrelations binding the pitch distance of the rotors, rotational speed, and pitch angle, vis à vis the thrust coefficient and power coefficient. Through the parameter optimization method, we demonstrate that adjusting rotor spacing offers a practical means to enhance payload capacity without increasing the power input, thereby improving efficiency, which validates the practicality and efficacy of the parameter optimization approach. Furthermore, optimizing rotor spacing for specific operational scenarios enhances overall aerodynamic performance, suggesting a viable flight control strategy for takeoff and landing conditions for coaxial drones.

This study investigates the impact of rotor spacing on the aerodynamic performance of a coaxialcopter. It has been observed that a small distance between two rotors can result in significant interaction between the propellers, consequently affecting the rotor's aerodynamic efficiency. Exploiting this characteristic, the present research introduces a coaxialcopter with variable rotor spacing. Employing finite element numerical simulations, we assess the aerodynamic behavior of this novel configuration. Through comprehensive measurements and analysis of its aerodynamic performance across varying rotor spacings from 0.1R to 1R, we validate the effectiveness of a rotor spacing control strategy for enhancing takeoff maneuvers. Our numerical simulation results reveal that the performance characteristics of both upper and lower rotor converges toward that of a single rotor as pitch ratio increases, along with the reduce of their thrust fluctuations and aerodynamic performance periodicity. Considering stable power consumption patterns and endurance performance, we analysis the interrelations binding of pitch distance of the rotors, rotational speed, and pitch angle, vis-à-vis the thrust coefficient and power coefficient. Through parameter optimization method, we demonstrate that adjusting rotor spacing offers a practical means to enhance payload capacity without increasing power input, thereby improving the efficiency, which validates the practicality and efficacy of the parameter optimization approach. Furthermore, optimizing rotor spacing for specific operational scenarios enhances overall aerodynamic performance, suggesting a viable flight control strategy for takeoff and landing conditions.

The precise regulation of hinge moment and pitch angle driven by the pitch regulated mechanism is crucial for modulating thrust requirements and ensuring stable attitude control in Martian coaxial rotorcraft. Nonetheless, the aerodynamic hinge moment in rotorcraft presents time-dependent dynamic properties, posing significant challenges for accurate measurement and assessment for such characteristics. In this study, we delve into the detailed aerodynamic hinge moment characteristics associated with the pitch regulated mechanism of Mars rotorcraft under a spectrum of control strategies. A robust computational fluid dynamics model has been developed to simulate rotor’s aerodynamic loads, accompanied by a quantitative hinge moment characterization that takes into account the effects of varying rotor speeds and pitch angles. Our investigation has yielded a thorough understanding of the interplay between aerodynamic load behavior and rotor surface pressure distributions, leading to the creation of an empirical mapping model for hinge moments. To validate our findings, we engineered a specialized test apparatus capable of measuring the hinge moments of the pitch regulated mechanism, facilitating empirical assessments under replicated atmospheric conditions of both Earth and Mars. The result indicates aerodynamic hinge moments depend non-linearly on rotational speed, peaking at a 0° pitch angle and showing minimal sensitivity to pitch under 0°. Above 0°, hinge moments decrease, reaching a minimum at 15° before rising again. Simulation and experimental comparisons demonstrate that under Earth conditions, the aerodynamic performance and hinge moment errors are within 8.54% and 24.90%, respectively. For Mars conditions, errors remain below 11.62%, proving the CFD model’s reliability. This supports its application in the design and optimization of Mars rotorcraft systems, enhancing their flight control through accurate prediction of aerodynamic hinge moments across various pitch angles and speeds.

The recycling and secondary utilization of retired power batteries have become increasingly important with the rapid growth of new energy vehicle ownership. Assessing their residual value and guiding trade-in decisions have emerged as key challenges. This study proposes a dynamic residual value assessment and trade-in decision framework for multi-scenario secondary applications. The framework integrates operational data, maintenance records, and market and policy information to characterize battery condition through feature extraction and health indicator construction. A dynamic residual value function combines state of health, remaining useful life, and market adjustment factors to account for nonlinear battery degradation and changing economic conditions. Residual value grading and application scenario matching guide the allocation of retired batteries to suitable utilization pathways. A standardized closed-loop process covering inspection, registration, evaluation, transactions, logistics, and reuse links assessment outcomes to trade-in pricing and implementation. The framework provides a structured basis for residual value assessment, allocation for secondary utilization, and trade-in decision-making for retired power batteries.