【作者】 汪岸柳；

【导师】 聂宏；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2012， 博士

【摘要】 未来月球探测需要到月面任何地方观察需要知道的任何信息，这要求月球着陆器在复杂多变的月球环境和突发条件下能安全、可靠的着陆及返回。作为着陆器的重要部分，着陆缓冲系统目前仍是被动控制技术，其系统结构及参数固定，一旦制成装机后，无法改变自身特性以适时响应外界激励的变化，难以完全满足未来着陆器的要求。在继续改进被动控制技术的同时，采用半主动控制技术也成为研究方向之一。本文的主要研究内容如下：选取四腿铰接悬臂式着陆器为研究对象，建立单套着陆腿软着陆动力学模型，同时考虑铝蜂窝缓冲材料和一般的缓冲材料。建立单套着陆腿软着陆动力学仿真模型，并以相应的落震试验结果验证，证明了所建模型精确、有效。分析研究了着陆器初始速度、月面摩擦、月面斜角、主支柱轴承摩擦以及反推火箭等对着陆器软着陆的影响。研究表明，应尽量降低初始速度；当摩擦系数确定时，着陆腿的张开角不宜设计过小；下坡着陆比上坡着陆的影响大；轴承摩擦对主、辅助缓冲器有一定的保护作用；反推火箭开机着陆对降低机体过载有明显的作用，推重比的选择以0.6为宜。选取着陆器2-2着陆模式，建立9自由度软着陆动力学模型及其仿真模型，并通过相应的落震试验结果验证，证明所建模型精确、有效。分析研究了着陆器初始速度、月面斜角、着陆初始姿态角、反推火箭推力对软着陆性能的影响，并提出安全角面的概念以分析机体初始姿态角与月面斜角对着陆器的耦合影响。研究表明，水平速度会降低机体的最大过载，降低着陆稳定性；下坡着陆时，月面斜角降低着陆稳定性；初始姿态角在0到0.16rad范围内减小机体最大过载；开机着陆稳定性较高，上坡开机着陆稳定性最好；月面斜角与着陆器初始姿态角的夹角越大，机体的最大过载越大，着陆稳定性越差；对最大过载要求严格，会导致着陆器安全角面变小；月面水平，机体姿态角水平时机体最大过载较大。提出一种适合于着陆器的旁通式磁流变阻尼器构型，并建立其动力学模型，模型考虑了紊流状态的影响和阻尼通道的局部阻力。进行旁通式阻尼器结构参数的初步设计，建立了阻尼器的跌落实验仿真模型，分析了流体行为指数、修正模型的影响，并设计一种以缓冲行程限值来开启不同电流的二级缓冲的模型。研究表明，磁流变阻尼器在缓冲行程、最大过载与缓冲效率方面均能满足着陆器的着陆要求，最大行程、最大过载随电流强度变化，这说明了阻尼力可控和可行；剪切稀化会降低阻尼器的出力和缓冲效率；修正模型的磁流变阻尼器缓冲性能差、缓冲效率低、最大过载大；二级缓冲的磁流变阻尼器，通过适当的设计，能够同时拥有低电流强度与高电流强度的优点。提出月球着陆器软着陆缓冲控制方法，建立了四分之一机体软着陆数学模型。首先设计电压状态反馈最优控制和力最优控制，之后设计状态跳跃、多态控制以及模糊逻辑控制等，及其控制器。仿真分析着陆器软着陆缓冲控制，分析其控制效果以及对初始条件的敏感性。研究表明，电压最优控制虽然缓冲性能最好，很好的减缓着陆后期机体的振动，但在线计算量大；力最优控制降低机体的最大过载最明显，但是完全拟合出这种最优控制力比较困难；状态跳跃控制的结构响应限值选取很重要；多态控制策略的调节参数的大小以0.5到0.8范围内较好；模糊控制的效果非常好，应尽量降低运算时间，可以采用离线计算。提出着陆器软着陆稳定控制方法，建立了固接1-1着陆数学模型，将软着陆过程为两阶段，并进行稳定性分析。设计了状态跳跃控制、多态控制以及模糊控制策略，及其控制器。仿真分析软着陆稳定控制，分析其控制效果，以及对初始条件敏感性。研究表明，状态跳跃、多态控制和模糊控制能很好的降低着陆器的着陆过载，减小着陆最大姿态角变化，提高着陆稳定性，对初始速度以及安全角敏感性较好。综合控制效果最好的为模糊控制，多态控制、状态跳跃控制次之。三种控制器对着陆初始条件和着环境适应性强，满足了未来着陆器在复杂环境和突发条件下安全着陆的要求。更多还原

【Abstract】 Lunar exploration in future requires to land anywhere to be landed and to observe anything tobe observed. That means lunar lander should be able to land and return safely and reliably even intough lunar environments and emergency landing conditions. However, as an important part oflander, the buffer system still uses passive control technologies and cannot meet the requirementsof the lander of next generation. The main reason is that the buffer system does not changeits characteristics to respond timely to external excitation after it is located andparameters are fixed. Passive control technologies should continue to be improved. At the sametime, semi-active control technologies have also become research direction. The main researchcontents are as follows:A type of lunar lander with four cantilever hinged legs is selected for research and a softlanding dynamic model is developed for a single set of landing leg, the aluminumhoneycomb cushioning materials and the general buffering materials are also put intoconsideration. The soft landing dynamic model for a single set of landing leg is simulated andvalidated by the corresponding drop test. As a result, the model is proved accurate and effective. Inthe research process, the author also analyzed the impacts on soft landing of lunar lander from theaspects of initial velocity of lunar lander, the friction on the surface, the slope of lunar surface, thebearing friction of the primary strut, and the thrust of the retro-rocket. It is proved that the initialvelocity should be reduced as much as possible. When the friction coefficient is determined, therange of the opening angle should not be designed too small. The impact of downhill landing ismuch more than uphill landing. The bearings friction can protect the primary and secondarybuffering systems. The retro-rocket with engine power is significant to reduce overload duringlanding, and it is appropriate to choose0.6as the thrust-weight ratio.The2-2landing mode of lunar lander is selected and a soft landing dynamic model with9DOF is established. Through the corresponding drop test, the mode is proved accurate andeffective. The soft landing performance impacts of the initial velocity of lander, the angle of lunarslope, the angle of initial landing attitude and the thrust of the rocket are analyzed. By doing so,the concept of safe angle scope is proposed to analyze the coupling effects of the slope of lunarsurface and the attitude of lunar lander. The results show that the horizontal speed will reducethe body’s maximum overload and landing stability. When downhill landing, the lunar anglereduces the stability. In the range of0to0.16rad, the initial attitude angle will reducethe maximum overload. The stability of landing with engine power is higher; the stability of uphillwith engine power is the best. The larger the angle between the initial attitude of lunar lander and the slope of lunar surface, the greater the overload of lunar lander, and the worse thelanding stability. If the maximum overload is critical, the safe angle scope is small. When the lunarsurface and the body attitude are both level, the maximum overload is much larger.A configuration of bypass-type MR damper is designed for lunar lander and the dynamicmodel of the bypass damper is established, the impacts of turbulent state and the local resistanceof damping channel are also put into consideration. A sketch of the bypass-type damper is givenwith structural parameters, and a drop test simulation of the damper is built. The impact of thefluid behavior index and corrected model are analyzed in simulation. A model with two differentcurrent buffers operated by the limits of buffer stroke is designed. Study showsthat MR dampers can meet the requirements of lunar soft landing in the buffer stroke, maximumoverload and buffer efficiency. The maximum buffer stroke can be adjusted and the maximumoverload can be changed by current intensity, which provides the controllability and feasibility ofdamping of lunar lander. Shear-thinning will reduce the output force and buffer efficiency of thedamper. The corrected model of MR damper has worse buffer performance, lowerbuffer efficiency and larger maximum overload. When designed legitimately, A MR damper withtwo buffers can also have the advantages of both low current intensity and high current intensity.The buffer control method of soft landing is proposed and the mathematical model of aquarter of lunar lander is established. The first step is to design the state feedback optimal controlsof voltage and force, and the second step is to design the three semi-active control strategies,including jump-state, multistate and fuzzy logic control, and their controllers. The soft landingbuffer controls of lunar lander are simulated and their control effects and the sensitivities to initialcondition are analyzed. The results show that the optimal control of voltage can provide the bestcushioning performance, and reduce vibration during post-landing, but its online computation timeis too long. The optimal control of force is best for the reduction of the maximum overload, but itis difficult to completely fit the optimal force. It is very important to choose the structuralresponse limits for jump state control. It is better to adjust parameter of multistate control strategyfrom0.5to0.8. The fuzzy control is very effective. Off-line calculation can be used to reduce thecomputation time.The stability control method of soft landing is proposed and the mathematical model of a1-1landing mode with fixed legs is established. The process of soft landing is refined as twophases and the landing stability is analyzed. Three strategies, such as Jump-state control strategy,multi-state control strategy and fuzzy logic control strategy, are established, and their controllersare designed. The stability controls for soft landing are simulated and their control effects and thesensitivities to initial conditions are analyzed. Research shows that jump-state control, multi-statecontrol and fuzzy logic control can largely reduce the maximum overload and the maximum attitude angle, improve the stability of soft landing, the sensitivities to initial velocity and safetyangle scope. Fuzzy logic control is the best in integrated control effects, and then the multi-statecontrol and jump-state control. These three control methods have strong adaptability to landingconditions and lunar environments, so that they can meet the requirements of lunar lander even inextreme landing conditions and tough lunar environments.更多还原