Abstract This paper investigates the rigid–liquid–flexible coupled dynamic characteristics of geostationary orbit (GEO) satellites under impulsive thrust perturbations induced by station-keeping maneuvers. For the symmetrically mounted plate-type solar panels (flexible appendages), the Kirchhoff–Love (KL) plate theory is adopted for modeling, and the coupled vibration equations are derived via D’Alembert’s principle; the governing equations are further transformed into nonlinear state-space formulations through spatial discretization and order truncation for efficient numerical calculation. For liquid sloshing in the axisymmetric propellant tank, the carrier velocity potential is solved based on the motion of a characteristic point in the tank, and the relative velocity potential is expanded as a Gaussian hypergeometric series. Hamilton’s variational principle is employed to establish the integrated coupled governing equations that incorporate liquid propellant sloshing, satellite rigid-body dynamics, and flexible plate vibrations. The proposed coupled dynamic model is comprehensively validated against satellite on-orbit telemetry measurements and ground experimental data of liquid-filled propellant tanks. Moreover, the on-orbit dynamic responses of the satellite are systematically analyzed under north–south and east–west station-keeping processes driven by 10-N thrusters. Comparative numerical simulations are conducted to reveal the critical coupling behaviors among liquid sloshing, flexible structural vibration, and satellite attitude motion, as well as quantify the influences of liquid fill ratios and thruster firing modes on satellite attitude pointing accuracy and stability. The results provide a theoretical basis for the design and control of high-precision GEO spacecraft with liquid-filled tanks and flexible appendages.
Abstract Transition maneuvers of tiltrotor aircraft require coordinated control of nacelle position while maintaining airspeed and altitude, resulting in high pilot workload. This paper proposes a pilot-assisted conversion control approach that accounts for the transitional aerodynamic characteristics of the rotor–wing system. A conversion path and corresponding nacelle rate distribution are derived by extracting phase-dependent lift characteristics from rotor and wing aerodynamic forces. Based on a stability and control augmentation system (SCAS), a pilot-assisted control architecture is developed by integrating scheduled pitch attitude and collective pitch with an altitude error compensator, establishing a coordinated transition framework that combines tilting rate with aerodynamic surface regulation. Simulation and flight test results showed that the proposed method reduces stick activity and pilot workload through coordinated regulation of altitude and speed. The transition exhibits small variations in altitude and pitch attitude, consistent with the underlying aerodynamic characteristics. By aligning configuration transition with lift–thrust variation and synchronizing nacelle tilt with aerodynamic control, the method improves flight state evolution and reduces pilot control effort.
Abstract National Aeronautics and Space Administration (NASA) is preparing to deploy astronauts for detailed exploration of the lunar South Pole, an area primarily composed of lunar highlands regolith. A comprehensive understanding of the composition, properties, and behavior of this surface material is critical to the success of the mission, to advancing the field of lunar exploration research, and future endeavors on the Moon. This study showcases the findings from laboratory tests conducted using a scaled-down model of two types of compaction equipment: a vibrating smooth drum roller (VSDR) and a rolling dynamic compaction (RDC) 4-sided impact roller. The experiments were performed using 1:13 scale models and utilized lunar highland simulant as the test material. Surface settlements, earth pressure cells, and densities were measured to quantify the extent of improvement for these two different compaction techniques. The results indicate that the vibrating smooth drum roller technique outperforms the impact roller in surface settlement, density, earth pressure and acceleration, demonstrating superior performance in compacting lunar highland regolith simulant.
To address the ineffective fault isolation of static diagnosis strategies under field-testing constraints, this paper proposes a dynamic fault diagnosis approach for oil systems based on an improved information entropy algorithm, along with a multifault isolation method. The study analyzes field constraints, introduces the algorithm, and describes a diagnostic framework adaptable to imperfect testing. Using a temporary local fault-test correlation matrix (D-matrix) enhanced with field constraints, dynamic strategy formulation and multifault isolation are demonstrated. Experimental results showed significant improvements over rollout and particle swarm optimization (PSO) algorithms: the isolation rate increased by about 17% and 14%, the average misdiagnosis cost dropped by about 63% and 41%, the detection rate rose by 8.4% and 6.9%, the type I false alarm rate decreased by 97%, and runtime was reduced by 73% and 83%. In multifault scenarios, correctly isolated samples increased from 33 to 40 for two faults and from 70 to 80 for three faults, confirming the method's effectiveness in improving fault isolation for field applications.
