Hybrid-polynomial-based optimization for buffer mechanism of asteroid probe with uncertainty

Purpose For a legged-type asteroid probe (AP), the buffer mechanism’s (BM’s) performance determines whether it can achieve a reliable soft landing. Therefore, this paper aims to improve the BM's comprehensive performance by conducting multi-objective design optimization. Because of the unknown asteroid environment and limited controller accuracy, the uncertainty should be considered in the optimization calculation. Design/methodology/approach The dynamic model of an AP is established, and performance evaluation parameters and working condition parameters are presented to achieve the quantitative analysis of the probe’s performance. Then, the surrogate models of the dynamic model are fitted by a hybrid polynomial to improve the performance evaluation efficiency. A hybrid polynomial consists of power and trigonometric function terms, which can accurately estimate the boundaries of performance evaluation parameters under uncertain working conditions based on interval analysis theory, thereby constructing optimization objective functions. The buffer spring parameters are selected as design variables, and the multi-objective optimization algorithm is used for iterative calculation. Findings Dynamic simulation results verify the rationality of the design scheme of the BM. After optimization, the spring compression stroke is reduced by 6.56%, the dip angle of the main body is reduced by 2.07% and the safety distance of the bottom nozzle is increased by 2.85%. Practical implications This paper provides theoretical guidance for improving the AP’s design level, especially ensuring the robustness of optimization results. Originality/value This study demonstrates the feasibility of the hybrid polynomial method in the performance optimization of an AP, which will enrich the corresponding design theory.