一种仿生附着装置柔顺关节的优化设计

为提高仿生附着装置在捕获空间非合作目标物时对目标运动参数的适应性,设计了一种3自由度串联柔顺关节,可通过关节嵌入系统后的协调运动来辅助装置被动适应运动目标物姿态,并在运动过程中基于弹簧、阻尼缓冲器组成的关节柔顺机构及其能量耗散原理来降低目标物动能。为验证、优化关节性能,通过ADAMS虚拟样机软件建立了基于柔顺关节的仿生附着装置捕获过程运动学与动力学模型,分析了柔顺关节3组弹簧刚度系数、黏滞阻尼系数对非合作目标物捕获状态的影响,并利用ADAMS-iSIGHT联合仿真平台,通过多岛遗传算法对上述弹簧、阻尼器的重要参数进行了优化,极大提高了柔顺关节的能量耗散效果,同时保证了可捕获目标物运动参数达到规定要求。      

LEO enhanced Global Navigation Satellite System (LeGNSS) for real-time precise positioning services

Global Navigation Satellite System (GNSS) has been widely used in many geosciences areas with its Positioning, Navigation and Timing (PNT) service. However, GNSS still has its own bottleneck, such as the long initialization period of Precise Point Positioning (PPP) without dense reference network. Recently, the concept of PNTRC (Positioning, Navigation, Timing, Remote sensing and Communication) has been put forward, where Low Earth Orbit (LEO) satellite constellations are recruited to fulfill diverse missions. In navigation aspect, a number of selected LEO satellites can be equipped with a transmitter to transmit similar navigation signals to ground users, so that they can serve as GNSS satellites but with much faster geometric change to enhance GNSS capability, which is named as LEO constellation enhanced GNSS (LeGNSS). As a result, the initialization time of PPP is expected to be shortened to the level of a few minutes or even seconds depending on the number of the LEO satellites involved. In this article, we simulate all the relevant data from June 8th to 14th, 2014 and investigate the feasibility of LeGNSS with the concentration on the key issues in the whole data processing for providing real-time PPP service based on a system configuration with fourteen satellites of BeiDou Navigation Satellite System (BDS), twenty-four satellites of the Global Positioning System (GPS), and sixty-six satellites of the Iridium satellite constellations. At the server-end, Precise Orbit Determination (POD) and Precise Clock Estimation (PCE) with various operational modes are investigated using simulated observations. It is found out that GNSS POD with partial LEO satellites is the most practical mode of LeGNSS operation. At the user-end, the Geometry Dilution Of Precision (GDOP) and Signal-In-Space Ranging Error (SISRE) are calculated and assessed for different positioning schemes in order to demonstrate the performance of LeGNSS. Centimeter level SISRE can be achieved for LeGNSS.     

基于GA-SVM的GNSS-IR土壤湿度反演方法

针对提高大范围土壤湿度测量精度的问题,研究了土壤湿度的全球卫星导航系统干涉测量法（GNSS-IR）,提出了一种基于支持向量机（SVM）的土壤湿度反演模型,利用遗传算法（GA）的自动寻优功能寻找SVM的最佳参数。结果表明,GA-SVM模型在测试集上得到的土壤湿度反演值与实测值的平均绝对百分比误差（MAPE）仅为0.69%,最大相对误差（MRE）为1.22%,线性回归方程决定系数达到了0.956 9。进一步与统计回归、粒子群优化的SVM模型（PSO-SVM）及反向传播（BP）神经网络方法进行对比,结果说明:在样本数目有限的情况下,GA-SVM方法更适用于土壤湿度的GNSS-IR技术反演,且反演精度较高,泛化性能良好。      

空间柔性臂的解耦动力学模型及其控制

提出了一种空间柔性结构通过关节电机同时实现轨迹控制和振动抑制的方法。针对单连杆空间柔性臂,采用非约束模态法建立了刚柔解耦动力学模型;提出了基于应变反馈的PID控制策略,并设计了PID／应变反馈复合控制器,同时实现对柔性臂末端运动轨迹的定位控制和弹性振动抑制控制;仿真结果验证了该控制策略的可行性。     

遥感卫星高精度高稳定度控制技术

对遥感卫星高精度高稳定度控制技术进行了综述。给出了国内外高稳定度多挠性遥感卫星控制、快速机动控制、高精度姿态确定、自主智能控制等典型应用,以及未来发展趋势。分析了挠性多体卫星结构-控制一体化设计、卫星在轨试验和高精度姿态确定等关键技术。讨论了挠性多体卫星动力学建模仿真及地面试验验证,H∞控制、自适应滤波前馈等卫星姿态控制方法研究与应用,卫星结构模态与无干扰力矩在轨辨识,以及基于陀螺、星敏感器及其误差、卫星动力学模型、在轨热变形标定等高精度姿态确定技术。     

柔性接头频率特性的计算方法研究

为防止作动器驱动力矩载荷频率与柔性接头固有频率的共振，需确定柔性接头的频率特征。本文给出了柔性接头频率特征的计算公式，包括对固有频率，共振频率，稳态摆幅，共振摆幅以及摆动角速度和角加速度的分析，给出了设计算例，供柔性接头设计时参考。     

飞机静电环境特性研究

飞机上的静电主要由飞机表面与物质粒子发生碰撞而形成,静电会引起许多影响飞机安全及系统效能的问题。本文分析了产生静电的各种途径,并介绍了静电的危害以及飞机的静电防护措施。     

A conceptual configuration of the lunar base bioregenerative life support system including soil-like substrate for growing plants

The paper presents a conceptual configuration of the lunar base bioregenerative life support system (LBLSS), including soil-like substrate (SLS) for growing plants. SLS makes it possible to combine the processes of plant growth and the utilization of plant waste. Plants are to be grown on SLS on the basis of 20 kg of dry SLS mass or 100 kg of wet SLS mass per square meter. The substrate is to be delivered to the base ready-made as part of the plant growth subsystem. Food for the crew was provided by prestored stock 24% and by plant growing system 76%. Total dry weight of the food is 631 g per day (2800 kcal/day) for one crew member (CM). The list of candidate plants to be grown under lunar BLSS conditions included 14 species: wheat, rice, soybean, peanuts, sweet pepper, carrots, tomatoes, coriander, cole, lettuce, radish, squash, onion and garlic. From the prestored stock the crew consumed canned fish, iodinated salt, sugar, beef sauce and seafood sauce. Our calculations show that to provide one CM with plant food requires the area of 47.5 m². The balance of substance is achieved by the removal dehydrated urine 59 g, feces 31 g, food waste 50 g, SLS 134 g, and also waters 86 g from system and introduction food 236 g, liquid potassium soap 4 g and mineral salts 120 g into system daily. To reduce system setup time the first plants could be sowed and germinated to a certain age on the Earth.