A multiple-CubeSat constellation for integrated earth observation and marine/air traffic monitoring

CubeSats has evolved from purely educational tools, to useful platforms for technology demonstration and many practical applications. This paper reviews a CubeSat constellation mission involving 3 CubeSats launched into orbit on Sep. 25th 2015, aiming to demonstrate the integrated application of low-cost CubeSat technologies with distributed payloads using a group of satellites, as well as to demonstrate several new technologies. The mission scenario, the satellite system design, the innovative technologies and instruments or devices used on the CubeSats and the in-orbit experimental results and the payload data analysis, as well as some experiences and lessons learned, are presented and summaried.     

基于载波相位的多通道相位一致性测量方法CSCD

对于卫星导航系统,由导航天线进行波束合成的多路并行导航信号需要具有严格的相位一致性,本文给出基于专用地检设备的多通道相位一致性测量方法。该地检设备采用载波相位辅助伪码测距技术,通过载波相位和伪码相位的联合解算,实现了伪码相位对载波相位解整周期模糊,最终测距精度达到1ps。采用该测试方法对系统进行配相,实现了各通道无周期模糊的相位一致性。     

An integrated graphic–taxonomic–associative approach to analyze human factors in aviation accidents

Human factors are critical causes of modern aviation accidents. However, existing accident analysis methods encounter limitations in addressing aviation human factors, especially in complex accident scenarios. The existing graphic approaches are effective for describing accident mechanisms within various categories of human factors, but cannot simultaneously describe inadequate human–aircraft–environment interactions and organizational deficiencies effectively, and highly depend on analysts' skills and experiences. Moreover, the existing methods do not emphasize latent unsafe factors outside accidents. This paper focuses on the above three limitations and proposes an integrated graphic–taxonomic–associative approach. A new graphic model named accident tree(AcciTree), with a two-mode structure and a reaction-based concept, is developed for accident modeling and safety defense identification. The AcciTree model is then integrated with the well-established human factors analysis and classification system(HFACS) to enhance both reliability of the graphic part and logicality of the taxonomic part for improving completeness of analysis. An associative hazard analysis technique is further put forward to extend analysis to factors outside accidents, to form extended safety requirements for proactive accident prevention. Two crash examples, a research flight demonstrator by our team and an industrial unmanned aircraft, illustrate that the integrated approach is effective for identifying more unsafe factors and safety requirements.     

语音识别技术应用于航空控制系统

介绍了语音识别技术基本原理及在航空控制领域的应用。     

Evaluation of airborne data link communication

An experimental prototype of a cockpit data link communication interface (modified Navigation Display (ND) and Multi-purpose Control and Display Unit (MCDU)) was developed and tested in an Airbus A340 Full Flight Simulator. 8 crews (16 professional pilots) performed simulator flights in a mixed voice and data link scenario. After each experiment video recordings were presented to the pilots and they were asked to estimate subjective strain (NASA task load index) and situational aspects retrospectively. Results show an increase in subjective strain and a decrease of ‘feeling of sovereignty’ and situation awareness under data link conditions. The effect is similar to the one caused by higher workload.     

Comparison of strapdown inertial navigation algorithm based on rotation vector and dual quaternion

 For the navigation algorithm of the strapdown inertial navigation system, by comparing to the equations of the dual quaternion and quaternion, the superiority of the attitude algorithm based on dual quaternion over the ones based on rotation vector in accuracy is analyzed in the case of the rotation of navigation frame. By comparing the update algorithm of the gravitational velocity in dual quaternion solution with the compensation algorithm of the harmful acceleration in traditional velocity solution, the accuracy advantage of the gravitational velocity based on dual quaternion is addressed. In view of the idea of the attitude and velocity algorithm based on dual quaternion, an improved navigation algorithm is proposed, which is as much as the rotation vector algorithm in computational complexity. According to this method, the attitude quaternion does not require compensating as the navigation frame rotates. In order to verify the correctness of the theoretical analysis, simulations are carried out utilizing the software, and the simulation results show that the accuracy of the improved algorithm is approximately equal to the dual quaternion algorithm.     

Integration of GPS and low cost INS for pedestrian navigation aided by building layout

In outdoor environments, GPS is often used for pedestrian navigation by utilizing its signals for position computation, but in indoor or semi-obstructed environments, GPS signals are often unavailable. Therefore, pedestrian navigation for these environments should be realized by the integration of GPS and inertial navigation system （INS）. However, the lowcost INS could induce errors that may result in a large position drift. The problem can be minimized by mounting the sensors on the pedestrian＇s foot, using zero velocity update （ZUPT） method with the standard navigation algorithm to restrict the error growth. However, heading drift still remains despite using ZUPT measurements since the heading error is unobservable. Also, tbot mounted INS suffers from the initialization ambiguity of position and heading from GPS. In this paper, a novel algorithm is developed to mitigate the heading drift problem when using ZUPT. The method uses building lay- out to aid the heading measurement in Kalman filter, and it could also be combined for the initial- ization. The algorithm has been investigated with real field trials using the low cost Microstrain 3DM-GX3-25 inertial sensor, a Leica GS10 GPS receiver and a uBlox EVK-6T GPS receiver. It could be concluded that the proposed method offers a significant improvement in position accuracy for the long period, allowing pedestrian navigation for nearly40 min with mean position error less than 2.8 m. This method also has a considerable effect on the accuracy of the initialization.     

新舟600飞机综合航电系统特点及跨机型比较

新舟600(以下简称MA600)是中航西飞公司生产的新一代涡桨支线客机。它采用了较为先进的Proline21综合航电系统,该系统和民航飞行学院运行的CJ1和CJ1+机型采用了同样的航电平台,但同时具有其独特性。本文分析了MA600飞机的构型特点及其与奖状机型的异同点,有助于机务维修人员掌握新机型系统构型特点,以便更好地进行飞机维护。     

空间相机隔振与姿态控制一体化设计

为了解决星上微振动导致高分辨率遥感卫星图像质量下降的问题,研究了空间相机隔振措施及其带来的异位控制问题,提出了同时采取相机隔振与控制规律修改措施的一体化设计方法,实现了隔振性能与姿态控制性能兼备的系统方案。对算例的研究结果表明,采用相机隔振-姿态控制一体化设计方法可以在保证姿态控制性能的同时大幅降低曝光时间内空间相机的视线抖动量。     

一体化热防护技术现状和发展趋势

防隔热/承载一体化热防护的结构承载功能使其比传统热防护具有更高的结构效率。近年来,已经发展了波纹夹芯一体化热防护及改进方案、刚性隔热夹芯一体化热防护、多层级一体化热防护等多种一体化热防护概念。首先介绍了各方案的结构特征,分析了各方案的热短路效应和结构承载性能。阐述了一体化热防护等效性能分析与热力耦合响应高效分析方法。介绍了热力耦合约束下一体化热防护的结构尺寸优化与材料优选方法。论述了一体化热防护非确定性分析与设计方面的研究进展。在此基础上,总结了一体化热防护发展的特点和不足,探讨了一体化热防护的发展方向。