一种非仿射高超声速飞行器姿态系统控制方法

针对非仿射高超声速飞行器姿态控制问题,提出了一种基于反步法的非线性控制方法.首先,通过干扰观测器估计攻角动态中的扰动量,在此基础上设计了俯仰角速度虚拟控制指令.然后,针对含有非仿射项的参数不确定的俯仰角速度动态函数,将其视为一个扩张状态,通过状态观测器对其进行估计.接着,基于动态逆方法设计了升降襟副翼的控制律并基于李雅...     

液氧/煤油高压补燃火箭发动机非线性稳态模型——考虑推进剂温升与密度变化

针对液氧／煤油高压补燃循环液体火箭发动机,考虑了推进剂供应系统中的温度与密度变化,推导建立了改进的简化非线性稳态特性数学模型。并通过数值模拟分析验证了该改进的非线性稳态模型可行性。     

多传感器融合状态估计方法综述

随着传感器网络技术的发展,多传感器融合状态估计凭借其鲁棒性、灵活性、可扩展性以及便于故障检测等优点,长期受到国内外学者的广泛关注,并取得了大量研究成果。数据融合的方法为融合状态估计奠定了理论基础,也是早期研究的主要方向,从20世纪70年代到20世纪末,相继发展出了集中式和分散式滤波架构及相应算法。无线通信技术的成熟以及一致性算法的出现使得分布式状态估计的研究进入了快车道,自2005年以来,大量基于一致性的分布式滤波算法被提出,其中不乏实用的经典方法和优秀的开创性方法。旨在梳理多传感器融合状态估计的发展,探究从数据融合到分布式滤波的内在联系,并对一些经典方法进行了总结。     

基于压缩感知的金属加筋板兰姆波健康监测技术

针对大型复杂板结构安全评价需要，发展了一种基于压缩感知的金属加筋板结构兰姆波健康监测技术。利用压缩感知技术从稀疏阵列得到的少量检测数据中恢复出加筋板结构中兰姆波的频散特性，并提出了一种将余弦相似度和皮尔森相似度相结合的稀疏阵列兰姆波复合成像方法，以实现加筋板结构中大范围缺陷检测和成像。实验结果表明，压缩感知技术可以恢复出金属加筋板中兰姆波的频率-波数关系，提出的兰姆波复合成像方法能够实现金属加筋板中单缺陷和多缺陷的检测及定位。研究工作为复杂板结构损伤检测提供了一种可行的技术方案。     

Effect of salt stress on growth and physiology in amaranth and lettuce: Implications for bioregenerative life support system

Growing plants can be used to clean waste water in bioregenerative life support system (BLSS). However, NaCl contained in the human urine always restricts plant growth and further reduces the degree of mass cycle closure of the system (i.e. salt stress). This work determined the effect of NaCl stress on physiological characteristics of plants for the life support system. Amaranth (Amaranthus tricolor L. var. Huahong) and leaf lettuce (Lactuca sativa L. var. Luoma) were cultivated at nutrient solutions with different NaCl contents (0, 1000, 5000 and 10,000 ppm, respectively) for 10 to 18 days after planted in the Controlled Ecological Life Support System Experimental Facility in China. Results showed that the two plants have different responses to the salt stress. The amaranth showed higher salt-tolerance with NaCl stress. If NaCl content in the solution is below 5000 ppm, the salt stress effect is insignificant on above-ground biomass output, leaf photosynthesis rate, Fv/Fm, photosynthesis pigment contents, activities of antioxidant enzymes, and inducing lipid peroxidation. On the other hand, the lettuce is sensitive to NaCl which significantly decreases those indices of growth and physiology. Notably, the lettuce remains high productivity of edible biomass in low NaCl stress, although its salt-tolerant limitation is lower than amaranth. Therefore, we recommended that amaranth could be cultivated under a higher NaCl stress condition (<5000 ppm) for NaCl recycle while lettuce should be under a lower NaCl stress (<1000 ppm) for water cleaning in future BLSS.     

Constrained adaptive fault-tolerant attitude tracking control of rigid spacecraft

A saturated fault-tolerant attitude tracking controller for disturbed rigid spacecraft is derived using nonlinear state feedback control method. The proposed controller achieves the constraints of control inputs by directly using the bounded function instead of the traditional saturation compensator technique, and the active tolerance to the partial loss of actuator effectiveness is also achieved by directly using the known bounds of the actuator faults in the controller. Specifically, compared with the traditional saturated control methods, a continuously bounded nonlinear function in the proposed controller is used to guarantee that the actuator outputs are smoothly bounded under the prescribed constraints. Based on some properties of the attitude tracking dynamics, the proposed controller can ensure the attitude tracking errors converge to small neighborhoods of zero via stability analysis in the Lyapunov framework. Simulation results are presented to illustrate the effectiveness of the control scheme.     

SpaceMocap：在轨人体运动捕捉系统

SpaceMocap是一套基于多RGB-D相机的计算机视觉航天员运动捕捉系统。地面准备阶段，扫描航天员模型，并分别标定彩色相机的内参数。在轨采集阶段，3~4台相机布置在舱内角落，同步采集航天员任务视频。地面处理阶段，通过相机外参数标定和ICP方法实现点云融合，采用深度神经网络对人体关节点位置进行检测并初始化位姿参数，再用改进的ICP方法进行位姿求精，实现序列图像中关节角度跟踪。本系统搭载TG-2升空，对SZ-11航天员的任务视频进行了采集和处理，首次获取了在轨航天员的姿态(包括中性体位)、占位空间、运动参数等重要数据。结果表明，运动捕捉的模型与点云具有良好的重合度，关节点位置与关节角度具有较高的跟踪精度。SpaceMocap是我国首个在轨运动捕捉系统，它小型、轻质，具有计算机视觉特有的非接触测量、直观、高精度优势，无需在人体上粘贴任何标志，具有良好的抗遮挡能力，完全适用于微重力、狭小空间环境下的在轨应用 。     

Software defect prevention based on human error theories

Software defect prevention is an important way to reduce the defect introduction rate.As the primary cause of software defects,human error can be the key to understanding and preventing software defects.This paper proposes a defect prevention approach based on human error mechanisms:DPeHE.The approach includes both knowledge and regulation training in human error prevention.Knowledge training provides programmers with explicit knowledge on why programmers commit errors,what kinds of errors tend to be committed under different circumstances,and how these errors can be prevented.Regulation training further helps programmers to promote the awareness and ability to prevent human errors through practice.The practice is facilitated by a problem solving checklist and a root cause identification checklist.This paper provides a systematic framework that integrates knowledge across disciplines,e.g.,cognitive science,software psychology and software engineering to defend against human errors in software development.Furthermore,we applied this approach in an international company at CMM Level 5 and a software development institution at CMM Level 1 in the Chinese Aviation Industry.The application cases show that the approach is feasible and effective in promoting developers' ability to prevent software defects,inde pendent of process maturity levels.     

中子星性质的模型依赖性

采用相对论平均场理论（RMFT）下的GL85,GL92,TM1和TM2等核物质参数组,研究了这些参数组对中子星的粒子数密度分布、状态方程及质量-半径关系的影响.结果表明,在不同的参数组下,超子出现的密度、顺序和种类均不同;状态方程的软硬情况也较大不同;中子星的引力质量和相应的半径有明显不同.计算结果也表明,采用GL85,TM1和TM2等参数组得到的中子星质量和半径均在脉冲星的观测数据范围内,而采用GL92参数组得到的中子星质量小于中子星质量下限1.4M⊙（M⊙=1.99×1030kg为太阳质量）.     

Docking control for probe-drogue refueling: An additive-state-decomposition-based output feedback iterative learning control method

Designing a controller for the docking maneuver in Probe-Drogue Refueling (PDR) is an important but challenging task, due to the complex system model and the high precision requirement. In order to overcome the disadvantage of only feedback control, a feedforward control scheme known as Iterative Learning Control (ILC) is adopted in this paper. First, Additive State Decomposition (ASD) is used to address the tight coupling of input saturation, nonlinearity and the property of NonMinimum Phase (NMP) by separating these features into two subsystems (a primary system and a secondary system). After system decomposition, an adjoint-type ILC is applied to the Linear Time-Invariant (LTI) primary system with NMP to achieve entire output trajectory tracking, whereas state feedback is used to stabilize the secondary system with input saturation. The two controllers designed for the two subsystems can be combined to achieve the original control goal of the PDR system. Furthermore, to compensate for the receiver-independent uncertainties, a correction action is proposed by using the terminal docking error, which can lead to a smaller docking error at the docking moment. Simulation tests have been carried out to demonstrate the performance of the proposed control method, which has some advantages over the traditional derivative-type ILC and adjoint-type ILC in the docking control of PDR.