Method for Collision Avoidance in Spacecraft Rendezvous Problems with Space Objects in a Phasing Orbit

As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision should be derived.In this paper,a maneuvering method is proposed for avoiding collision with a space debris object in the phasing orbit of the initial optimal solution.Accordingly,based on the plane of eccentricity vector components,relevant dangerous area which is bounded by two parallel lines is formulated.The axises of eccentricity vector system pass through the end of eccentricity vector of phasing orbit in the optimal solution,and orientation of axis depends on the latitude argument where a collision will occur.The dangerous area is represented especially with the graphical dialogue,and it allows to find a compromise between the SO avoiding and the fuel consumption reduction.The proposed method to solve the collision avoidance problem provides simplicity to calculate rendezvous maneuvers,and possibility to avoid collisions from several collisions or from“slow”collisions in a phasing orbit,when the protected spacecraft and the object fly dangerously close to each other for a long period.

Compressive sensing for small moving space object detection in astronomical images

It is known that detecting small moving objects in as- tronomical image sequences is a significant research problem in space surveillance. The new theory, compressive sensing, pro- vides a very easy and computationally cheap coding scheme for onboard astronomical remote sensing. An algorithm for small moving space object detection and localization is proposed. The algorithm determines the measurements of objects by comparing the difference between the measurements of the current image and the measurements of the background scene. In contrast to reconstruct the whole image, only a foreground image is recon- structed, which will lead to an effective computational performance, and a high level of localization accuracy is achieved. Experiments and analysis are provided to show the performance of the pro- posed approach on detection and localization.

Scheduling Optimization of Space Object Observations for Radar

An optimizing method of observation scheduling based on time-division multiplexing is proposed in this paper,and its efficiency is verified by outdoor experiments. The initial observation scheduling is first obtained by using a semi-random search algorithm,and secondly the connection time pair（ CTP） between adjacent objects is optimized by using a genetic algorithm. After obtaining these two parameters,the final observation scheduling can be obtained. According to pre-designed tracks between each adjacent objects in observation order,the seamless observation of neighboring targets is derived by automatically steering the antenna beam,so the observation efficiency is improved.

Re-Entry of Space Objects from Low Eccentricity Orbits

This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), −86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), −89.01deg. (Long.) with an altitude of 143.5 km.

Multi-view space object recognition and pose estimation based on kernel regression

The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions.

An analysis of close approaches and probability of collisions between LEO resident space objects and mega constellations

With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting(LEO)satellites,space will become even more congested for satellite operations.The enduring effects on the long-term space environment have been investigated by various researchers using debris environment models.This paper is focused on the imminent short-term effects of LEO mega constellations on the space operation environment concerned by satellite owners and operators.The effects are measured in terms of the Close Approaches(CAs)and overall collision probability.Instead of using debris environment models,the CAs are determined from integrated orbit positions,and the collision probability is computed for each CA considering the sizes and position covariance of the involving objects.The obtained results thus present a clearer picture of the space operation safety environment when LEO mega constellations are deployed.Many mega constellations are simulated,including a Starlink-like constellation of 1584 satellites,four possible generic constellations at altitudes between 1110 km and 1325 km,and three constellations of 1584 satellites each at the altitudes of 650 km,800 km,and 950 km,respectively,where the Resident Space Object(RSO)spatial density is the highest.The increases in the number of CAs and overall collision probability caused by them are really alarming.The results suggest that highly frequent orbital maneuvers are required to avoid collisions between existing RSOs and constellation satellites,and between satellites from two constellations at a close altitude,as such the constellation operation burden would be very heavy.The study is not only useful for satellite operators but a powerful signal for various stakeholders to pay serious attention to the development of LEO mega constellations.

Research of Underwater Bottom Object and Reverberation in Feature Space

批评技术问题在水下底部对象察觉为回响信号正在成立一个稳定的特征空格分类。更多在特征空间和回响在目标回响的特征上集中的过去的文学仅仅被当作干扰。在这篇论文，回响与稳定的特征，并且在频率聚类回响被看作一种信号分离小浪变换(FDWT ) 特征空格被学习。为了提取回响信号，特征压缩和簇的识别信息，分析在在目标回响之间的可分性的这篇论文，和标准被采用，回响被给。处理回响举办的结果表演的试验性的数据在不同于对象的 FDWT 特征空格的稳定的模式回应。在回响和目标回响之间有可分性，这被证明。

Study on Logical Relations amongUnderground Survey Objects Using Quotient Topological Space

A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological space, the author studies the logical relations among underground survey objects, a partiallyordered space uuder some conditions. An example is given to show the data model’s possible applications.

Multi-objective Collaborative Optimization for Scheduling Aircraft Landing on Closely Spaced Parallel Runways Based on Genetic Algorithms

A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controller and the maximum fairness of airlines′scheduling.The time interval between two runways and changes of aircraft landing order were taken as the constraints.Genetic algorithm was used to solve the model,and the model constrained unit delay cost of the aircraft with multiple flight tasks to reduce its delay influence range.Each objective function value or the fitness of particle unsatisfied the constrain condition would be punished.Finally,one domestic airport hub was introduced to verify the algorithm and the model.The results showed that the genetic algorithm presented strong convergence and timeliness for solving constraint multi-objective aircraft landing problem on closely spaced parallel runways,and the optimization results were better than that of actual scheduling.

Multi-objective Evolutionary Algorithm Based on Target Space Partitioning Method

Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimization problem, thus achieve the coherent solution which can meet the requirements of all target functions, and improve the population's overall evolution level. The algorithm which guarantees diversity preservation and fast convergence to the Pareto set is applied to structural optimization problems. The empirical analysis supports the algorithm and gives an example with program.

PartLabeling:A label management framework in 3D space

Background In this work,we focus on the label layout problem:specifying the positions of overlaid virtual annotations in Virtual/Augmented Reality scenarios.Methods Designing a layout of labels that does not violate domain-specific design requirements,while at the same time satisfying aesthetic and functional principles of good design,can be a daunting task even for skilled visual designers.Presenting the annotations in 3D object space instead of projection space,allows for the preservation of spatial and depth cues.This results in stable layouts in dynamic environments,since the annotations are anchored in 3D space.Results In this paper we make two major contributions.First,we propose a technique for managing the layout and rendering of annotations in Virtual/Augmented Reality scenarios by manipulating the annotations directly in 3D space.For this,we make use of Artificial Potential Fields and use 3D geometric constraints to adapt them in 3D space.Second,we introduce PartLabeling:an open source platform in the form of a web application that acts as a much-needed generic framework allowing to easily add labeling algorithms and 3D models.This serves as a catalyst for researchers in this field to make their algorithms and implementations publicly available,as well as ensure research reproducibility.The PartLabeling framework relies on a dataset that we generate as a subset of the original PartNet dataset consisting of models suitable for the label management task.The dataset consists of 10003D models with part annotations.

Additional Space Dimension in Bound Spaces Created by a Central Object

Space is a common entity in any static or dynamic system of objects whether the system is a bound system or an open system. Space is described by either measured or abstract dimensions. All motions, momentum and energy transfers take place in space in any given system of objects. By understanding space we understand many physical phenomena happening in space. One method is to observe similarities among phenomena, deduce possible relations and validate the relations through known results. De Broglie wavelength for matter waves is a typical theorized abstract dimension existence of which is established through experiments later. In this paper, the author studies two bound spaces in two bound systems, namely, atomic bound systems and gravitationally bound systems. Both these bound systems have similar characteristics;they have inertial masses in motion with constant kinetic energies for a given orbital distance around the respective central object. In atomic bound space, the central object is the central positive charge which plays the role of creating the bound space around it. In gravitationally bound space, it is the central mass that plays the same role. Thus for these two bound systems a common constitutive relation between the energies of inertial masses in kinetic state, their distance from central object could be present. By noticing the similarities of the two systems, the author proposes such a relation through introduction of an additional space dimension. The existence of the proposed additional dimension is proved in this paper by considering hydrogen atom for atomic bound space and by considering any gravitational system for gravitationally bound space. Though the magnitude of the additional space dimension is different in both the situations, the additional space dimension exists. It is observed that in hydrogen atom the additional space dimension is a constant for the given positive charge of hydrogen atom when electron is in any energy state having principal quantum number of any value from 1 to 5 and with the orbital quantum number zero. For other quantum numbers additional space dimension exists. In the case of gravitational bound space, the additional space dimension is constant for a given mass of the central object for any energy of orbiting inertial mass. The author concludes that total mass energy of an inertial mass having a constant kinetic energy in any bound space is related to an additional space dimension defined by the constitutional property of the central object creating that bound space. As the relation is generic, it throws opportunity to examine other known similar macro, micro or quantum bound spaces created by central objects with different constitutive properties.

Application of camera calibrating model to space manipulator with multi-objective genetic algorithm

The multi-objective genetic algorithm(MOGA) is proposed to calibrate the non-linear camera model of a space manipulator to improve its locational accuracy. This algorithm can optimize the camera model by dynamic balancing its model weight and multi-parametric distributions to the required accuracy. A novel measuring instrument of space manipulator is designed to orbital simulative motion and locational accuracy test. The camera system of space manipulator, calibrated by MOGA algorithm, is used to locational accuracy test in this measuring instrument. The experimental result shows that the absolute errors are [0.07, 1.75] mm for MOGA calibrating model, [2.88, 5.95] mm for MN method, and [1.19, 4.83] mm for LM method. Besides, the composite errors both of LM method and MN method are approximately seven times higher that of MOGA calibrating model. It is suggested that the MOGA calibrating model is superior both to LM method and MN method.

Multi-Scale Object Perception with Embedding Textural Space

This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representation to purse the underlying textural manifold statistically in nonparametric manner. The associative method approximately makes perceptual hierarchy in human-vision biologically coherency in specific quad-tree-pyramid structure, and the appropriate scale-value of different objects can automatically be selected by evaluating from well-defined scale function without any priori knowledge. The sufficient experiments truly demonstrate the effectiveness of scale determination in textural manifold with object localization rapidly.

天基空间态势感知数据仿真研究进展

空间态势感知(Space Situational Awareness,SSA)数据仿真可以为空间监测设备及态势感知算法(包括空间目标检测、跟踪、识别和表征)的开发、测试和验证提供关键性数据支持,在空间态势感知能力建设中发挥重要作用。本文以天基空间态势感知光学数据仿真为研究对象,给出了SSA数据仿真的研究目的和主要研究内容,详述了SSA光学成像仿真的典型研究方法与过程。介绍了国内外相关工作的研究现状与工作进展,涵盖双目视觉传感器、激光雷达、红外传感器、可见光望远镜和恒星敏感器等不同光学传感系统的成像建模与仿真工作成果。分析了空间态势感知数据仿真研究的发展趋势,为未来SSA数据仿真研究思路与方法提供参考。

基于光学成像探测的仅测角高轨空间物体接近感知方法

提出一种仅利用任务航天器光学成像探测设备给出的测角信息进行高轨空间物体接近行为感知的方法。首先,分析了空间物体相对任务航天器的方位变化规律,得到物体接近时在任务航天器轨道坐标系下方位角正切值随时间波动幅值逐渐增大;其次,分析了在光学成像探测设备成像过程中,逆光与探测设备灵敏度对空间物体可见性的影响,得到物体可见弧段在每个轨道周期内具有一定的相似性;进一步地,根据物体相对方位及可见性的变化规律,设计了一种空间物体接近行为感知方法,利用物体观测量的轨道周期一致性进行多段观测量关联,拟合方位角正切值随时间波动趋势,预测波动极值并统计极值变化规律,实现物体接近行为感知;最后,仿真验证了该方法具备不依赖距离信息感知高轨空间物体相对任务航天器接近行为的能力,仅利用3个轨道周期内、每周期有效弧段大于30 min的高轨空间物体指向测量信息判断物体相对任务航天器存在接近行为的准确率优于96%。结果证明:该方法通过赋能任务航天器常用光学成像探测设备高效费比地实现航天器自我防护能力有效提升,可普遍用于高轨航天器任务。

自由漂浮空间机器人捕获翻滚目标的力-位-型融合控制方法

翻滚目标捕获过程中,空间机器人的运动会对基座产生扰动、接触过程的冲击碰撞容易产生安全风险。因此,为了在捕获翻滚目标的同时抑制空间机械臂对基座的扰动和对目标的碰撞冲击,提出一种自由漂浮空间机器人力-位-型融合控制方法。首先将自由漂浮空间机器人的非完整冗余性、运动冗余性表征为型空间,构建由末端位姿、型状态组合的广义状态空间并建立系统的运动学和动力学模型;通过优化基座与机械臂的位-型及零空间运动,减小机械臂抓捕运动在基座产生的扰动;通过优化基座、机械臂与翻滚目标的相对位-型,减小碰撞冲击力在基座产生的姿态扰动。给定最优位-型及末端操作力,基于阻抗控制原理及零空间投影策略,实现多优先级力-位-型融合控制。最后,开展了空间机器人捕获翻滚目标的典型任务仿真,结果表明通过力-位-型融合优化与控制方法可以有效减小空间机器人捕获过程产生的基座扰动。

众创空间的政策反馈研究

基于政策反馈理论,以全国数据为样本,探析达成众创空间政策目标的因果复杂机制。研究发现:资源效应、解释效应、演化效应、学习效应和营商环境能够以组态形式达成政策目标;解释效应是达成政策目标的关键核心条件;不同政策目标所需政策资源和强度具有明显差异。各政策目标均产生了5条组态路径,可归纳为3种构型,即并驾齐驱型强调全要素政策资源配置;主动有为型注重解释效应为关键基础;辅以其他政策资源,无为而治型则倾向于依赖市场运行机制,鼓励自由生长。

客货共运模式的高铁货运发展空间分析

在铁路运输技术不断改善的背景下,高速铁路的运输条件得到了大力改善,运力也得到了相应增加,货物运输变得更加快捷、安全、可靠。利用高铁开展快捷货物运输可以满足高附加值、高时效要求的快递市场需求。针对该现状,考虑高铁、高速公路和民航之间的货运竞争,在由若干OD形成的货运网络中,以客运动车组预留车厢模式下总运输利润最大为目标,构建基于多目标的客货共运模式的高铁货运双层规划模型,计算货运网络中高铁的运价以及货流量在高铁快运网络中的分布。通过NSGA-Ⅱ多目标优化算法,求出Pareto最优解。最后以京沪间快递运输为例,验证所建模型的有效性。算例结果表明:预留货运车厢模式对于高铁客运的影响较小,可以增加高铁的盈利能力,在一些客运量不足的短途高铁线路上可以开展客货共运模式,以增加高铁收益,增强高铁在短途运输中对于公路货运的竞争力。