A Comparison of Two Approaches to Pure-Inertial and Doppler-Inertial Error Analysis

Error equations for inertial navigation systems are derived using a perturbation (or true frame) approach and a psi angle (or computer frame) approach in a manner which shows the underlying as sumptions and allows direct comparison of the two methods. The comparison is general since the analysis is not associated with any particular mechanization. Different definitions of velocity errors and misalignment angles result from the two methods of error analysis, and, consequently, have significance in testing and analysis of pure-inertial systems, Doppler-inertial systems, and inertially aided weapon delivery systems. Examples and numerical results are presented for a local-level north-pointing mechanization.     

Cubesat solar sail 3-axis stabilization using panel translation and magnetic torquing

A Cubesat mission with a deployable solar sail of 5 meter by 5 meter in a sun-synchronous low earth orbit is analyzed to demonstrate solar sailing using active attitude stabilization of the sail panel. The sail panel is kept parallel to the orbital plane to minimize aerodynamic drag and optimize the orbit inclination change caused by the solar pressure force normal to the sail surface. A practical control system is proposed, using a combination of small 2-dimensional translation of the sail panel and 3-axis magnetic torquing which is proved to have sufficient control authority over the gravity gradient and aerodynamic disturbance torques. Miniaturized CMOS cameras are used as sun and nadir vector attitude sensors and a robust Kalman filter is used to accurately estimate the inertially referenced body rates from only the sun vector measurements. It is shown through realistic simulation tests that the proposed control system, although inactive during eclipse, will be able to stabilize the sail panel to within ±2° in all attitude angles during the sunlit part of the orbit, when solar sailing is possible.     

Mini-UAV altitude estimation using an inertially stabilized payload

A novel method is introduced for autonomous attitude estimation of a mini unmanned aerial vehicle (UAV) carrying an inertially stabilized payload. The method is based on utilizing the outputs of rate gyros normally used to inertially stabilize the payload, and other data that is normally available from conventional aircraft-mounted sensors. A decentralized estimation algorithm is developed, which uses the aircraft/payload mathematical models to bound the estimation errors. Exploiting modern multiprocessor computer technology, the new estimation algorithm comprises two parallel extended Kalman filters (EKFs) and a data fusion algorithm. Real-time experimental tests, incorporating a payload model with real rate gyros mounted on a three-axis flight table, have validated the feasibility of the concept. The theoretical and experimental investigation demonstrates that the estimation algorithm is capable of estimating the attitude angles with an estimation error not exceeding 1 deg, at output rates of 13 Hz, thus constituting a viable substitute for the conventional vertical gyroscope     

应用旋转矩阵的卫星姿态输出反馈机动控制

针对卫星姿态机动控制问题,提出一种只利用向量测量信息的无角速度反馈的输出反馈控制方法。卫星姿态的指向直接通过旋转矩阵进行描述,而不是先进行参数化过程,避免了由欧拉角、修正的罗德里格参数（MRPs）与四元数等姿态描述方式产生的奇异问题与退绕问题。首先,通过向量测量信息与一组期望姿态向量,引入一个新的姿态指向误差向量,并对其性质进行分析。其次,进一步结合主导滤波器的思想,设计了无需角速度信息的卫星姿态机动控制器,并应用Lyapunov理论,对闭环系统的全局稳定性进行了严格的证明。最后,对所提出的控制算法进行了数值仿真,其结果验证了所设计的输出反馈控制算法的可行性和有效性。     

武器装备研制项目管理知识体系框架

主要通过对武器装备研制项目管理的研究,在分析对比了武器装备研制项目管理和一般项目管理的联系与区别的基础上,提出了基于武器装备全寿命周期、全过程、全方位管理所需的武器装备研制项目管理知识体系的框(WE-PMBOK),该体系框架具有模块化、结构化的特点。     

千兆三余度AFDX 帧管理的形式化建模与验证

为了提升新一代航空电子全双工交换以太网（AFDX）网络的传输速率和余度设计可靠性，在AFDX 网络标准的基础上（ARINC 664 p7），建立千兆三余度AFDX 网络的帧管理机制模型并进行了形式化建模， 而且实现了AFDX 网络标准中描述的SkewMax 机制。使用UPPAAL 形式化工具对千兆三余度AFDX 网络帧 管理机制进行形式化验证，验证帧管理机制的完整性检查及冗余管理功能的可用性。结果表明，千兆三余度 AFDX 网络帧传输过程中不存在死锁。此外，针对标准AFDX 的冗余管理中一个帧的丢失可能会导致其冗余备 份的丢失的现象，提出在接收端设置一个队列，记录那些比连续帧更晚到达的冗余备份的帧序号，从而减少不 必要的丢帧，提高QoS 和数据完整性。形式化验证的结果可以作为千兆AFDX 网络标准制定和实际应用的参考。     

速度矢量滚转的运动学及气动力分析

速度矢量滚转定义为飞机在保持定常迎角的情况下,围绕其瞬时速度矢量所产生的无侧滑、速度保持为常值的旋转运动。对于典型的战术飞机,最大俯仰力矩是飞机方位的函数,在水平轨迹中出现在倾斜90°的情况,此时飞机的滚转速率达到峰值,迎角超过45°。最大滚转力矩依赖于滚转模态时间常数。对于较小的滚转时间常数（快速响应）,最大滚转力矩出现在最大滚转加速度、零迎角,基本与飞机的方位无关;对于较大的滚转时间常数,最大滚转力矩出现在最大滚转速率、迎角最大、倾斜角180°的水平飞行中。最大的航向力矩出现在最大滚转加速度、迎角最大时,基本与飞机的方位无关。     

Distributed bearing-based formation control of unmanned aerial vehicle swarm via global orientation estimation

Most existing formation control approaches for Unmanned Aerial Vehicle(UAV)swarm assume that global position and global coordinate frame are directly available for each agent. To extend the application domain, this paper proposes a distributed bearing-based formation control scheme, without any reliance on global position or global coordinate frame. The interactions among UAVs are described by a directed topology with two-leader structure. To address the issue of unavailable global coordinate fr...     

刚体航天器最短时间姿态调整研究

在最小值原理的基础上，研究了完全刚体最短时间机动问题。由最小值原理推导出问题解的必要条件，采用修正开关时间优化算法，由遗传算法确定无耦合项时的开关特性；基于同伦算法的思想，引入松弛参数，采用模拟退火法确定开关点，对传统模拟退火法进行了改进。仿真结果表明，该方法简单可行，对实际工程有一定的参考价值。     

Nonlinear Estimation Via Kalman Filtering

The extended Kalman-Bucy filtering algorithm is applied to the problem of estimating the system parameters of a single-channel missile attitude control system. In particular, noisy observations of body angular rate, normal acceleration, and control surface deflec tion are used in the algorithm to obtain estimates of body angular rate, angle of attack, control surface deflection, air density, and missile velocity. Computational results obtained for this problem are presented. These results are evaluated to determine the applicapility of this estimator as a part of an adaptive control scheme. In addition, a general approach to the formulation of practical nonlinear estimation problems is suggested.     

Image-enhanced tracking

Measurement of the angular orientation of the target or the target designation makes possible the design of high-accuracy tracking and prediction systems. Such measurements are best accomplished with an imaging sensor. A model is presented for the image-based observation link, along with the equations used to convert a sequence of image processor outputs into an estimate of target status. An example examines the interrelationship which exists between the rate of feature changes of a target, the frame rate of the imager, and the sensitivity of the sensor-image processor. It is shown that even at high frame rates, anomalous events may occur     

考虑敏捷性的过失速机动优化研究

建立了考虑敏捷性的过失速机动优化模型 ,取飞机的滚转、俯仰转动角速度为控制变量 ,代替了传统的以迎角、速度矢滚转角为控制变量的优化方法 ,使得优化的结果能在一定程度上反映飞机的敏捷性。用罚函数处理约束条件 ,用共轭梯度法对飞机的最短时间 1 80°航向转弯进行了寻优计算 ,优化结果接近于六自由度仿真结果     

刚体飞行器大角度机动的反馈非线性化控制

研究了刚体飞行器大角度的姿态控制问题,采用四元数描述刚体姿态,建立了刚体姿态运动的数学模型。基于反馈非线性化技术,通过构造李雅普诺夫函数推导出标量增益的线性控制律和矩阵增益的非线性控制律。两种控制律不需要知道系统参数,对模型误差具有鲁棒性。理论分析和仿真结果表明,所求控制律对闭环系统具有全局渐近稳定性。     

基于多传感器信息融合的物体位姿检测方法

 提出了利用摄像机和超声传感器信息融合对机器人操作对象进行位姿检测的方法。该方法通过单幅图像获取目标点在图像中的理想坐标,求得投影矢量的方向,然后通过机器人末端的运动,导引超声传感器坐标原点与未移动前摄像机坐标系的原点重合,而其Z轴方向与求得的投影矢量方向相同,再由超声传感器测出投影矢量的长度,从而确定目标点在摄像机坐标系中的坐标,并可进一步转换到机器人基坐标系中。通过测量操作物体上两点的空间坐标,就能够确定物体空间姿态。该方法简单易行,计算量小,精度较高。     

大气层外拦截弹中段制导方法研究

针对大气层外拦截弹飞行中段采用固体燃料发动机，且关机后需要经过较长的无控滑行段才能进入末制导段的情况，提出一种基于拦截弹修正能力，且考虑无控滑行段拦截弹与目标引力差影响的中制导律。仿真表明，采用该制导律的拦截弹在发动机工作期间推力方向变化平稳，且可获得较高的制导精度。     

台速度估计(英文)

针对惯性稳定平台中高精度和高带宽的速度信号需求,提出了基于低成本MEMS传感器的最优速度估计算法。采用一种新颖的传感器组合形式,包括一个低带宽的MEMS陀螺和两个低性能的MEMS加速度计。陀螺由于自身动态特性的影响,主要提供速度的低频信息,加速度计组合则由于自身偏置的影响,主要提供速度的高频信息,而估计器将两者信号进行融合。实验表明:最优状态估计器能够在时频域上,提供无偏的、高性能的速度信号。同时,在单自由度微型惯性稳定平台的应用过程中,其控制性能得到了相应的提高。该算法也适用于机器人控制、姿态估计和摩擦补偿等领域。     

Autonomous attitude coordinated control for spacecraft formation with input constraint,model uncertainties,and external disturbances

To synchronize the attitude of a spacecraft formation flying system, three novel autonomous control schemes are proposed to deal with the issue in this paper. The first one is an ideal autonomous attitude coordinated controller, which is applied to address the case with certain models and no disturbance. The second one is a robust adaptive attitude coordinated controller, which aims to tackle the case with external disturbances and model uncertainties. The last one is a filtered robust adaptive attitude coordinated controller, which is used to overcome the case with input con- straint, model uncertainties, and external disturbances. The above three controllers do not need any external tracking signal and only require angular velocity and relative orientation between a spacecraft and its neighbors. Besides, the relative information is represented in the body frame of each spacecraft. The controllers are proved to be able to result in asymptotical stability almost everywhere. Numerical simulation results show that the proposed three approaches are effective for attitude coordination in a spacecraft formation flying system.     

基于改进SSD的舰船目标精细化检测方法

以SSD为代表的主流深度学习方法在目标检测领域取得了显著的成绩，但由于该类方法只能以矩形框给出目标的概略位置，检测结果具有很大的背景冗余区域，特别是港口密集停泊的舰船在图像中会出现区域重叠，导致误检和漏检。针对以上问题，提出了一种具有旋转不变性的舰船目标精细化检测方法，该方法综合利用可变形卷积、可变形池化、旋转的边框回归和旋转的非极大值抑制等模块的优点，借鉴MobileNet架构对网络加速，通过学习密集区域目标的几何形变，有效预测目标的旋转角度，最终以旋转的矩形框给出目标的位置。实验结果表明，该算法可实现多类舰船目标类型区分和目标朝向判定的功能，有效地解决了实际应用中的目标精确定位定向难题，提高了自动目标识别的精确性，并满足工程应用的实时性要求。     

基于邻帧差分近邻反相特征的红外运动点目标检测算法

基于运动点目标在邻帧差分图像中所具有的近邻反相特征,即运动点目标的两个位置相邻近、灰度值一正一负,提出一种在复杂背景下,基于红外序列图像的运动点目标检测算法.本算法利用该特征在邻帧差分图像中检测反相点对,进而构造反相点对矢量图,最后依据累积反相点对矢量图中多矢量首位相接的连续性检测出运动的点目标.文中给出并证明应用本算法能以概率1检测到运动点目标的收敛性定理.对典型复杂背景下10幅1000帧图像的仿真结果表明,当信噪比大于或等于1.5时,可以有效检测出运动点目标.     

基于螺旋理论的机械手最优位姿轨迹规划方法研究

提出了一种在笛卡儿空间实现机器人操作手最优位姿轨迹规划新方法。基于欧拉刚体有限转动定理,根据旋量理论和计算几何中三维直纹面路程参数生成原理,求以等效角位移矢量在空间的运动轨迹形成的直纹曲面面积及其变化率并考虑运动时的灵活性为泛函的泛函极值来实现以路径最短、运动灵活性最好、或动力学性能最优为目标的机器人位置和姿态轨迹优化生成,建立了相应的优化数学模型及求解方法。最后,用该法对三自由度平面机器人操作手进行了仿真计算。