Optimization of observer trajectories for bearings-only targetlocalization

The problem of bearings-only target localization is to estimate the location of a fixed target from a sequence of noisy bearing measurements. Although, in theory, this process is observable even without an observer maneuver, estimation performance (i.e., accuracy, stability and convergence rate) can be greatly enhanced by properly exploiting observer motion to increase observability. This work addresses the optimization of observer trajectories for bearings-only fixed-target localization. The approach presented herein is based on maximizing the determinant of the Fisher information matrix (FIM), subject to state constraints imposed on the observer trajectory (e.g., by the target defense system). Direct optimal control numerical schemes, including the recently introduced differential inclusion (DI) method, are used to solve the resulting optimal control problem. Computer simulations, utilizing the familiar Stansfield and maximum likelihood (ML) estimators, demonstrate the enhancement to target position estimability using the optimal observer trajectories     

Position and Velocity Estimation Via Bearing Observations

The problem of performing target motion analysis using noisy bearing measurements derived from multiple observation platforms or from a single moving observer is addressed. For the latter case, the properties of an estimator based on a Cartesian model of the process are detailed. Methods of providing estimates both before an observer maneuver, when the process is unobservable, and following an observer maneuver are developed. The results of an experimental study are presented.     

刚弹耦合飞行器的机动载荷减缓

针对飞行器刚体/弹性模态耦合作用下的机动载荷减缓问题,运用亚音速非定常空气动力学理论以及分析力学原理,建立了柔性飞机机动载荷分析及控制的气动弹性模型,分析了飞机作纵向机动飞行时结构弹性对机动飞行参数的影响。数值分析结果表明,结构弹性模态对飞机机动过程的影响不容忽视。为了有效减缓机动载荷,运用最优控制理论,采用多组控制面联合偏转的作动方案,设计机动载荷减缓最优控制律,实现了对飞机纵向机动载荷的控制。研究结果表明,提出的机动载荷减缓控制方案是有效的。     

机载单站只测向定位最优机动研究

概述了机载单站只测向定位最优机动求解算法，研究了基于最大方位角变化率准则下的观测机机动轨迹，得到理论上的最优定位机动，并结合实际运用，分析出两种近似最优的机动：“一”形（直线形）机动和S形机动，通过仿真，验证了这2种机动方式在一定条件下可以等效于最优机动，具有良好的定位效果。     

空间站伴随卫星的最优轨道机动

介绍了空间站伴随卫星的概念和轨道机动过程，给出了伴随卫星的轨道构型；建立了伴随轨道的最优机动模型，并对脉冲轨道机动进行了仿真计算，得出了伴随轨道最优机动轨迹、方位角和释放时间等的变化规律,研究结果对伴随卫星控制具有一定的参考价值。     

导弹靶弹弹道机动变轨通用控制指令设计

导弹进行一定强度的机动飞行,就能够提高突防能力,因而,在军事训练中需要具有末端机动变轨能力的靶弹.针对靶弹机动变轨弹道的设计问题,提出变轨通用控制指令设计形式,利用此设计可使靶弹位移与过载指令控制信号协调配合,控制靶弹实现跃升机动、蛇行机动、摆式机动和螺旋机动等变轨形式.通过仿真证明,此设计的变轨弹道通用控制指令,可以满足靶弹跃升机动、蛇行机动、摆式机动和螺旋机动等各种变轨形式的弹道设计要求.     

基于扰动观测器的无人机固定时间编队协同控制

针对无人机的编队控制问题,基于虚拟领航者编队方法,提出了 1种基于固定时间超螺旋干扰观测器的反步控制策略。首先,设计了 1种固定时间超螺旋扰动观测器,以保证在固定时间内,对无人机编队机动所受扰动的快速观测;其次,针对编队控制问题,设计了基于超螺旋扰动观测器的反步控制策略,该控制器显著降低了抖振效应;然后,使用李雅普诺夫理论和固定时间理论,分析了控制策略的固定时间稳定性;最后,通过仿真算例验证了所提出的控制策略的有效性与可行性。     

基于能量优化的无人机机动轨迹生成方法

基于能量优化的无人机机动能够使无人机在不失去决定性位置优势的情况下获取相对于对手的能量优势，足够的能量优势可转换为有效的位置优势，有利于无人机在空战中随时改出当前机动并投入下一机动动作，对于无人机获取空战胜利至关重要。开展了基于能量优化的无人机机动轨迹生成方法研究，通过在无人机机动飞行包线内设计合适的机动指令，使得无人机能量性能指标最优。以上升转弯机动为例进行了机动轨迹生成的详细设计，并与常规上升转弯机动轨迹生成结果进行对比，仿真结果显示所设计的机动动作完成时间缩短了28.6%~83.8%，总能量变化减少了64.7%~70.1%，实现了无人机机动飞行的能量优化。     

Orbital maneuver strategy design based on piecewise linear optimization for spacecraft soft landing on irregular asteroids

Recently, asteroid exploration becomes an important branch of human’s deep space activities. In this paper, a piecewise linear optimal orbital maneuver strategy is designed for a spacecraft soft landing on irregular-shaped asteroids. First, the space around an irregular asteroid is converted into several grid units, and the gravitational field of the asteroid is linearly fitted in each unit. Then, the soft-landing orbital maneuver strategy design problem is formulated as a piecewise linear optimal problem, and further transferred into a family of two-point boundary value problems, which can be solved using collocation method. Finally, a corresponding algorithm is developed to obtain the piecewise linear optimal maneuver strategy, which is proved to be able to achieve the soft-landing mission well. Simulation results show that the error of the model linearization is small enough, while the calculation efficiency is remarkably improved, and the robustness of maneuver strategy is also improved.     

A Decision?Directed Adaptive Tracker

In the design of a tracking filter for air traffic control (ATC) applications, a maneuvering aircraft can be modelled by a linear system with random noise accelerations. A Kalman filter tracker, designed on the basis of a variance chosen according to the distribution of the potential maneuver accelerations, will maintain track during maneuvers and provide some improvement in position accuracy. However, during those portions of the flight path where the aircraft is not maneuvering, the tracking accuracy will not be as good as if no acceleration noise had been allowed in the tracking filter. In this paper, statistical decision theory is used to derive an optimal test for detecting the aircraft maneuver; a more practical suboptimal test is then deduced from the optimal test. As long as no maneuver is declared, a simpler filter, based on a constant-velocity model, is used to track the aircraft. When a maneuver is detected, the tracker is reinitialized using stored data, up-dated to the present time, and then normal tracking is resumed as new data arrives. In essence, the tracker performs on the basis of a piecewise linear model in which the breakpoints are defined on-line using the maneuver detector. Simulation results show that there is a significant improvement in tracking capability using the decision-directed adaptive tracker.     

基于扩张状态观测器的动态逆过失速机动飞行控制

针对飞机过失速机动飞行控制问题,提出了一种将动态逆与扩张状态观测器相结合进行扰动估计补偿的新思路。根据时标分离原则将飞机状态分为快变量和慢变量,并分别设计了两个回路的动态逆控制器。在快慢回路分别引入扩张状态观测器对系统的不确定部分进行估计补偿,抵消不确定部分对系统动态特性的影响。最后对控制律进行了过失速机动仿真。结果表明,在存在较大参数摄动情况下,设计的控制律能控制飞机跟踪控制指令,表现出良好的稳定性和鲁棒性。     

Detumbling and reorientation maneuvers and stabilization of NASASCOLE system

The questions of rotational maneuver and vibration stabilization of the NASA Spacecraft Control Laboratory Experiment (SCOLE) system is considered. The mathematical model of the SCOLE system includes the rigid body dynamics as well as the elastic dynamics representing transverse and torsional deformations of the elastic beam connecting the orbiter and end body (reflector). For the rotational maneuver, a new control law (orbiter control law) is derived using an orbiter input torque vector. Detumbling and reorientation maneuvers of the SCOLE system are accomplished using this control law; however, this excites the elastic modes of the beam. The orbiter control law asymptotically linearizes the flexible dynamics. Using the linearized model, a linear feedback control law is designed for vibration suppression. An observer is designed for estimating the state variables using sensor outputs which are also used for the synthesis of the control law. Simulation results are presented to show that in the closed-loop system detumbling and reorientation maneuvers can be accomplished and the effect of control and observation spillover is insignificant     

机动目标的模型与跟踪算法

 <正> 在机动目标的“当前”统计模型中,目标的加速度被描述为修正的瑞利—马尔科夫过程,对应的自适应跟踪算法呈现出较好的跟踪特性。文献[2]研究了该模型及其自适应算法在实际的机载雷达跟踪系统的应用;文献[3]进一步推广了基于“当前”模型的MPDAF算法。本文提出一个新的机动目标模型,即假定目标加速度为一高斯—马尔     

有向拓扑条件下针对机动目标的分布式协同制导律设计

研究了在有向拓扑条件下针对机动目标的分布式协同制导律的设计问题。首先，根据飞行器与目标之间追击过程的几何关系建立制导过程系统模型，针对该模型的非线性问题采用动态反馈线性化方法进行处理。将目标未知机动视为干扰，通过扩张状态观测器进行观测，同时将该估计值用于制导律的设计中，通过直接补偿的方式剔除目标机动对飞行器剩余飞行时间的影响。然后，将所设计的制导律代入到制导模型中，利用一致性分析方法将多飞行器协同制导问题转化为一致性问题，利用极点分析的方法对非一致性子空间的收敛性进行分析，得到协同制导律收敛的充要条件。最后，通过仿真分析的方式对所设计的协同制导律以及制导律的参数选取方法进行分析。     

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     

Bearings-only tracking for maneuvering sources

Classical bearings-only target-motion analysis (TMA) is restricted to sources with constant motion parameters (usually position and velocity). However, most interesting sources have maneuvering abilities, thus degrading the performance of classical TMA. In the passive sonar context a long-time source-observer encounter is realistic, so the source maneuver possibilities may be important in regard to the source and array baseline. This advocates for the consideration and modeling of the whole source trajectory including source maneuver uncertainty. With that aim, a convenient framework is the hidden Markov model (HMM). A basic idea consists of a two-levels discretization of the state-space. The probabilities of position transition are deduced from the probabilities of velocity transitions which, themselves, are directly related to the source maneuvering capability. The source state sequence estimation is achieved by means of classical dynamic programming (DP). This approach does not require any prior information relative to the source maneuvers. However, the probabilistic nature of the source trajectory confers a major role to the optimization of the observer maneuvers. This problem is then solved by using the general framework of the Markov decision process (MDP)     

Evaluation on novel architecture for harmonizing manual and automatic flight controls under atmospheric turbulence

Pilot uncertainty in aircraft response under automatic flight control has triggered aircraft accidents/incidents in the past. This uncertainty compels a pilot to disengage autopilot and switch to manual control. However, the decision to disengage autopilot and when to do it can be difficult: especially if there is not enough time to monitor the cockpit displays, for instance while countering atmospheric turbulence. Against this background, we proposed the “human as a control module” architecture for harmonizing pilot and autopilot controls. The architecture blends pilot maneuver with autopilot control instead of switching between them when simultaneous inputs are given to the aircraft. By automatically adjusting pilot and autopilot control inputs, the architecture avoids overlaps of both control authorities and helps to circumvent the effect of conflicting actions. This paper applies the architecture to the situations of past aircraft incidents which had been caused by the transfer from autopilot control to pilot maneuver after encountering atmospheric turbulence. The effectiveness of the architecture is evaluated via simulation study for the specific incident examples. Furthermore, this paper extends the architecture with an Extended Kalman Filter (EKF) based observer and evaluates its robustness under errors in wind estimation.     

Optimal motion planning for dual-spacecraft interferometry

We address the question of design and optimal control of a class of dual-spacecraft interferometric imaging formations. The first main contribution is that we combine two ideas introduced separately in the literature and propose a maneuver that offers improved imaging performance. We then formulate an optimal control problem to minimize fuel consumption and maximize image quality by minimizing the relative speed, which is proportional to the signal-to-noise ratio (SNR) of the reconstructed image. We show that the necessary conditions are also sufficient and that the resulting optimal control is unique. Finally, we apply a continuation method to solve for the unique optimal trajectory.     

跟踪飞机机动的自适应滤波方法

本文研究了对目标机动的最优检测问题,针对飞机主要有三种飞行状态:匀速直线运动、加速直线运动与圆运动这一特点,提出了既探测飞机机动又同时判断飞机作何种形式的机动的方法;并建议对飞机的不同飞行状态,采用相应的动态模型。在此基础上,给出了自适应滤波方法。最后给出的仿真计算果表明,自适应滤波方法有较高的跟踪精度。     

应用轨迹优化技术评估战斗机的功能敏捷性

应用三维轨迹优化方法 ,推导出最优操纵律完成 1 80°偏航机动。分析采用优化操纵策略对功能敏捷性的三种评估尺度 (战斗周期时间、动态速率转弯图和相对能量状态 )的影响。结果表明最优操纵策略可以最大限度地减少敏捷性评估尺度受飞行员操纵因素的影响 ,明显地改善战斗机的功能敏捷性