月球漫游车关键技术初探

参考国外月球探测的现状,对月球车所涉及的关键技术问题进行了深入地分析与探 讨,提出了开发我国月球漫游车系统的具体实施方案．并针对月面的复杂环境,提出了建立 一套智能传感系统的思想,从而为实现漫游车在月面复杂、未知的环境中的自主导航与控制 提供了理论依据．     

HIT-1型月球车的运动学分析

为解决轮式移动机器人在崎岖地形中的运动问题，提出了基于摇杆-转向架的带有弹簧和移动滑块的月球车运动学分析方法，在此基础上详细分析了HIT-l型月球车的3D运动机制，推导了月球车的正向运动和反向运动求解．通过使用弹簧和关节滑块改变车体的质心分布，可加强车体运动重构性，提高车体的牵引力，有效地规划和控制月球车的动作．     

有限推力登月飞行器燃料消耗研究

首先介绍了使用基于双二体问题的圆锥曲线拼合法和齐奥尔科夫斯基公式进行登月飞行器燃料消耗量的计算方法;接着导出了地月固联三体坐标系中最优轨道情况下登月飞行器燃料消耗量的计算方法;最后给出了在一定推力范围内不同比冲常规发动机分别使用上述第1种方法得到的燃料消耗和使用上述第2种方法得到的发动机工作时间和燃料消耗的仿真结果。结果表明两种方法得到的结论吻合得很好。     

向月飞行轨道误差分析

根据月球探测器向月飞行轨道动力学方程式得到了飞行轨道误差的迭代方程,采用协方差分析方法对轨道初始误差误差源造成的轨道误差进行了分析,结合具体算例,给出了探测器初始轨道位置和速度误差引起的向月飞行轨道误差的时间历程和轨道终点误差。计算结果表明,若发射环月卫星,必须进行多次中途轨道修正。     

基于最小二乘法的月球探测器自主导航

对于地月转移轨道的月球探测器,其受力复杂,轨道动力学方程难以精确建立,因此难以应用已有的基于轨道动力学方程的滤波方法对其进行自主导航.文中提出了以太阳和恒星的天文信息为观测量,采用迭代最小二乘法进行纯几何解析定位来实现月球探测器自主导航的方法.最后还对定位结果的优化的进行了研究.通过数学仿真分析了敏感器精度、观测星个数等因素对定位精度的影响,结果表明这种方法简单可靠,可以作为深空探测自主导航的滤波方案的初值.     

A neutronics analysis of long-life, sectored compact reactor concepts for lunar surface power

Neutronics analysis is performed of low temperature (≤900 K) Sectored Compact Reactor (SCoRe-N_x) concepts for operational lives >20 years. They are cooled with circulating liquid Nak-78. The reactor vessel and the UN fuel pins cladding are made of stainless steel. The power systems with the SCoRe-N_x concepts have no moving parts and employ SiGe thermoelectric elements for converting the reactor’s thermal power to electricity at a load voltage >300 VDC. Separate SiGe elements power the electromagnetic pumps that circulate the liquid NaK-78 in the reactor and 6 pairs of primary and secondary loops. Analysis confirmed that the submerged bare reactors in wet sand and flooded with seawater, in the unlikely event of a postulated launch abort accident, are sufficiently subcritical. Results show that the SCoRe-N₅-S concept is capable of operating for 62 full power years at 200 kW_th, while requiring 75% of the control drums to shutdown the reactor at BOL. With only 50% of the control drums required at BOL to shutdown the reactor, its operational life decreases to 39 full power years.     

A general framework for three-dimensional surface reconstruction by self-consistent fusion of shading and shadow features

In this paper a novel framework for three-dimensional surface reconstruction by self-consistent fusion of shading and shadow features is presented. Based on the analysis of at least two pixel-synchronous images of the scene under different illumination conditions, this framework combines a shape from shading approach for estimating surface gradients and altitude variations on small scales with a shadow analysis method that allows for the determination of the large-scale properties of the surface. As a first step, the result of shadow analysis is used for selecting a consistent solution of the shape from shading reconstruction algorithm. As a second step, an additional error term derived from the fine-structure of the shadow is incorporated into the reconstruction algorithm. This approach is extended to the analysis of two or more shadows under different illumination conditions leading to an appropriate initialization of the shape from shading algorithm. The framework is applied to the astrogeological task of three-dimensional reconstruction of regions on the lunar surface using ground-based CCD images and to the machine vision task of industrial quality inspection.     

月球探测器重力转弯软着陆的最优制导

对于月球表面重力转弯软着陆过程,应用极大值原理研究了最优制导律,证明了其在 着陆过程中不存在奇异状态,并且至多进行一次开关切换.最后给出了一种易于实现的次优制 导律.     

模拟月壤螺旋钻进力载特性分析

月球钻探取样具有钻进对象松散、钻机功率小、质量轻、钻进过程无冲洗介质等难点,螺旋钻进因其连续排屑和干式回转钻进的能力,成为最具可行性的月球钻探取样方式之一。为确保在设备能力和月表环境限制下实现深层月壤钻探取样目的,针对月壤/模拟月壤物理力学特性,对螺旋钻探取样过程进行力载特性分析。分析表明,月球钻探具有螺旋叶片宽度窄、回转速度高的特点,可采用钻屑颗粒模式求得临界回转速度,然后选择合理的钻进工艺。螺旋钻进功耗包括钻头切削月壤的功耗和钻进排屑功耗,可根据功耗模型研究各变量对功率的影响规律,从而为钻具结构优化和钻进参数优选提供理论指导。     

Designing a powerful learning environment to promote durable conceptual change

The purpose of this study was to investigate the long-term effectiveness of a three-dimensional (3D) computer modeling supported predict–observe–explain (POE) strategy on pre-service science teachers' understanding of lunar concepts. Thirty-three preservice teachers participated in the study. A questionnaire was used to assess participants' understanding of the phases of the Moon and eclipses before, after, and 22 months after the instruction. Semi-structured interviews were conducted with six participants before and after the instruction. The results demonstrated that few participants had a scientific understanding about the targeted lunar concepts before the instruction. However, the majority of the participants had a scientific understanding after the instruction indicating that the instructional intervention was quite effective in facilitating conceptual change. The results also demonstrated that twenty-two months after the instruction most participants maintained their scientific conceptual understanding suggesting that the powerful learning environment designed for this study was effective in promoting a durable conceptual change.