Buffering mechanism and optimization of the mobility system with variable-stiffness wheel under lunar landing conditions

This paper investigates the impact dynamics of the variable-stiffness flexible wheel and lunar rover mobility system during lunar landing scenarios. A coupled numerical model for landing impact, incorporating the rover body, wheel, and lunar soil, is established based on the Coupled Eulerian-Lagrangian (CEL) method. The buffering performance of mobility system with flexible wheel under different stiffness states is investigated. Results demonstrate that the mobility system in high-stiffness configuration exhibits superior buffering performance, whereas under low-stiffness conditions, the peak acceleration increases by 11.75%. Meanwhile, in heavy load landings, lunar soil's plastic deformation dominates energy dissipation, averaging 79.68%. Subsequently, a 3-DOF analytical dynamics model is established. Together with the numerical results, it confirms that the degree of disturbance of the lunar soil by the flexible structure dominates the buffering performance. Based on the above findings, a surrogate model of the impact response is constructed using the response surface method (RSM). Multi-objective optimization results enhance the energy dissipation capability while reducing crater depth, which helps mitigate landing rebound and facilitate extrication. Finally, the effects of other factors on buffering performance are also examined, including the landing angle and spikes. An inclined landing increases crater depth while simultaneously improving buffering performance by reducing the impact force. Furthermore, the introduction of spikes reduces the buffering performance and poses strength requirements, requiring a trade-off analysis to balance the integrated demands of landing and mobility.