A magnetorheological (MR)shock strut with bypass was constructed and applied to lunar soft landing system for shock absorption and cushioning．A ground impact model of 1／4 lunar lander was built on the basis of the characteristics of machinery--ground interaction system．In consideration of its high velocity and high shear rate，the mechanical property of MR fluid was analyzed by Herschel-Bulkley model．Based on linear quadratic optimal(LQ)control theory，the optimal control force was solved and a state-jump algorithm was adopted to realize semi-active control during the process of soft landing．Compared with the passive and LQ control ones，the analysis results show that MR shock strut with bypass can provide controllable damping force and the overloading of semi-ac-tive state-jump control is reduced so much that it can ensure lunar lander smooth landing．At the end of landing process，the shock strut can come back to the original state．As a result，it ensures lunar lander ascent and landing again．%构造了一种旁路式结构的磁流变缓冲器,将其应用到月球软着陆系统中用来减振与缓冲.基于机械一月面系统的特性,建立了1/4月球着陆器软着陆地面冲击模型,考虑到磁流变的高速流、高剪切环境,采用Hershel-Bulkley模型来分析该缓冲器的磁流变力学特性.基于线性最优控制理论,求解出最优控制力,采用状态跳跃控制算法来实现着陆器软着陆的半主动控制,并与采用被动控制、最优控制算法的着陆器进行了对比分析.研究结果表明:该旁路结构磁流变缓冲器能够产生可控的阻尼力,而且采用的状态跳跃半主动控制算法能很好地降低过载,确保月球着陆器安全着陆;在着陆后期,缓冲器恢复到初始状态,能保证着陆器升空再着陆.
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