月球着陆器软着陆半主动多态控制

基于磁流变阻尼器在月球着陆器上应用的可行性及其阻尼的可控性,设计了一种磁流变缓冲装置.考虑到着陆时减速火箭的反推力影响以及着陆时地面撞击的作用,假设着陆器的着陆初始高度多变,建立了一种月球着陆器着陆地面冲击模型.根据着陆过程缓冲与减振的要求,采用了软着陆半主动多态控制策略.应用加速度与速度响应进行状态切换,并根据能量守恒原理确定出多态控制缓冲嚣的状态参数.3种不同被动控制进行比较分析.结果表明,半主动控制缓冲器能很好地降低着陆器着陆冲击时的过载,同时也能很好地减缓其着陆时的振动.采用半主动多态控制策略的着陆器对较高的着陆初始高度和较大的接地下沉速度的适应性很强,其缓冲效率随着着陆初始高度的增加而增加,在达到允许的最大加速度和允许的最大缓冲行程时,缓冲效率达到最高,这能很好地保障着陆器软着陆安全.

Semi-active Multistate Control of Soft Landing for Lunar Lander

Based on the feasibility of Magneto-Rheological(MR)shock strut application on lunar lander and the controlability of its damping, a magnetorheology shock aborber is designed .Considering the impact of retro-rocket reverse thrust and the characteristic of the machinery-ground interaction system, the changeableness of initial landing altitude is assumed and a ground impact model of 1/4 lunar lander is established. According to the requirements of the shock absorption and the vibration reduction during the process of soft landing, a semi-active multi-state strategy controI is proposed. The acceleration and the velocity response are used to switch the state,and the state parameters are determined by the energy balance law. Compared with three different passive ones, results show that the overloading of the lunar lander by semi-active control is evidently reduced. Meanwhile, the body vibration is effectively absorbed. Furthermore, its adaptability with the higher initial altitude and the touchdown sink rating is stronger and its buffer efficiency is enhanced with the increase of the initial landing altitude. When approaching the allowable peak acceleration and the maximal cushion stroke, its buffer efficiency is the highest. Thus, it can increase soft landing safety for lunar lander.