Physical properties and long-term evolution of the debris clouds produced by two catastrophic collisions in Earth orbit

The population of cataloged orbital debris increased by approximately 40% in just a couple of years, from January 2007 to February 2009. This was due to two collisions in space, which involved the catastrophic destruction of three intact satellites (Fengyun 1C, Cosmos 2251 and Iridium 33) in high inclination orbits. Both events occurred in the altitude range already most affected by previous launch activity and breakup events, thus boosting the cataloged population in low Earth orbit by more than 60%.     

基于协同进化粒子群和Pareto最优解的卫星编队队形重构方法

针对卫星编队自主队形重构问题,提出了基于协同进化粒子群优化(CPSO)和Pareto最优解的求解方法.首先,使用Legendre伪谱法(LPM)将队形重构问题离散化为非线性规划(NLP)问题;其次,根据卫星编队的特点及碰撞规避的需要,使用CPSO算法对重构问题采用既独立又集中的求解方式,避免了传统优化方法对梯度的求解;...     

Probability of Collision Error Analysis

The decision for the International Space Station (ISS) to maneuver to avoid a potential collision with another space object will be based on the probability of collision, P _C. The calculation of P _C requires the covariance of both objects at conjunction. It is well known that the covariance computed by US Space Command is optimistic (too small), especially at altitudes where atmospheric drag is the dominant perturbation, because its computation assumes there are no dynamic model errors. In this paper the effect of errors in the covariance on P _C and the sensitivity of P _C to the encounter geometry are investigated.     

MFOXBASE单用户到多用户转换及冲突处理的研究

本文通过ＭＦＯＸＢＡＳＥ，ＰＬＵＳ提供的一组出错命令和函数功能，解决怎样从单用户应用程序过渡到多用户应用程序，如何妥善处理因并发访问数据库而出现的冲突问题，使其在多用户环境下正常运行。     

飞机操纵系统舵机与助力器运动碰撞研究

飞机操纵系统中因舵机输出较快,助力器响应较慢而存在相互运动碰撞,影响操纵品质和飞行安全。对发生碰撞的机理进行了深入分析,建立了舵机与助力器运动特性匹配关系和用于碰撞研究的数学模型,通过实例,找到了对碰撞最有影响的参量。     

Collision Probabilities for Keplerian Orbits

We present a new derivation of the probability of collisions between spherical satellites occupying Keplerian orbits. The equations follow from the central concept of the instantaneous collision rate, an expression that describes the occurrence of collisions by using a Dirac -function. The derivation proceeds by showing how this instantaneous collision rate can be averaged over orbital mean anomaly angles and, additionally, over orbital precession angles to generate expressions appropriate for intermediate and long time scales. Collision rates averaged over mean anomalies tend to be non-zero during relatively brief collision seasons, when the peak collision probability may exceed the long-term average by several orders of magnitude. Derived precession-angle averages have a functional form similar but not identical to the collision probability expression derived using the spatial density approach of Kessler (Icarus, 48: 39–48, 1981), and the two methods have been found to yield numerical results to within 1% for all cases examined.     

基于合作的冗余度双臂机器人的避碰研究

冗余度双臂机器人在危险或太空环境中具有极高的应用价值，但是实现有效的和实时的合作是很困难的。在合作的双臂机器人之间实现避碰是成功地应用冗余度双臂机器人的关健。尽管基于距离函数的方法已被证明简单和有效，但是不同的避碰点经常会产生不同的避磋结果，甚至会导致失败。本讨论了避碰点的选择问题，提出了一种新的避碰点选择方法，并用冗余度平面机器人对该方法进行了验证。     

Progress in Space Debris Research

During recent years, A de-orbit disposal of SinoSat 2 satellite and the depletion of the residual propellant after SC/LV separation for all LM-4 series launch vehicles were carried out. Stuffed Whipple Shields based on hypervelocity impact particles were developed. Routine observation and collision avoidance were performed. The main progress in space debris research will be introduced from three aspects: mitigation, spacecraft protection, observation and collision avoidance.      

载人航天器空间碎片防护与减缓设计

为降低空间碎片撞击所带来的威胁,文章针对某载人航天器进行了空间碎片撞击风险分析,并设计了空间碎片专用防护结构,制定了轨道规避策略;同时针对重点设备进行钝化设计,并采用寿命末期有控离轨制动方案。以上措施可有效实现空间碎片减缓。     

拦阻钩初次碰撞道面反弹动力学

分析了飞机着舰拦阻时,拦阻钩初次接触道面碰撞后被反弹的动力学成因,建立了飞机拦阻钩碰撞道面的弹跳模型。研究了下滑轨迹角和甲板角对拦阻钩碰撞反弹角速度和拦阻钩所受冲量的影响,并分别考虑了航母俯仰运动和甲板凸起物对拦阻钩碰撞反弹性能的影响。结果表明：轨迹角约4°时,拦阻钩反弹角速度和其所受冲量随下滑轨迹角呈线性变化;反弹角速度与甲板角的余弦成反比,道面冲量与甲板角余弦的平方成反比;航母向上的俯仰运动和甲板凸起物增大了拦阻钩反弹角速度,凸起物达到一定角度时,机身推拦阻钩的冲量变为拉拦阻钩的冲量。该模型的结果为机身和拦阻钩装置的设计提供了重要依据。