无人机跟踪运动目标航迹规划算法

对无人机跟踪运动目标的原理进行了分析,设计了跟踪系统的动力学模型,提出了一种基于切线法的航迹规划算法。在动力学约束条件下实现了对无人机的航迹、速度、加速度等的最优控制,从而解决了无人机跟踪运动目标问题,并给出了算法的具体设计步骤。仿真结果表明,该算法能够快速、有效地为无人机规划出跟踪运动目标的最优航迹。     

基于UKF的双机协同纯角度目标定位路径规划

针对三维空间双机协同定位问题,在无迹卡尔曼滤波的基础上,提出一种规划双机路径的方法。首先,利用双机探测得到的方位角和俯仰角信息,并结合无迹卡尔曼滤波算法估计目标的状态;在此基础上根据交互信息理论提出指标函数的概念,以指标函数最大为轨迹优化的最优性能指标,将问题转化为求双机控制量的最优解;最后,采用遗传算法求解双机的控制量,得到比较合理的双机飞行路径。仿真结果表明,通过最大化指标函数可以有效地规划双机路径,且具有更高的精度和速度。     

A new vibrational genetic algorithm enhanced with a Voronoi diagram for path planning of autonomous UAV

A new optimization algorithm called multi-frequency vibrational genetic algorithm (mVGA) that can be used to solve the path planning problems of autonomous unmanned aerial vehicles (UAVs) is significantly improved. The algorithm emphasizes a new mutation application strategy and diversity variety such as the global random and the local random diversity. Clustering method and Voronoi diagram concepts are used within the initial population phase of mVGA process. The new algorithm and three additional GAs in the literature are applied to the path planning problem in two different three-dimensional (3D) environments such as sinusoidal and city type terrain models, and their results are compared. For both of the demonstration problems considered, remarkable reductions in the computational times have been accomplished.     

A grid algorithm for autonomous star identification

An autonomous star identification algorithm is described that is simple and requires less computer resources than other such algorithms. In simulations using an 8/spl times/8 degree field of view (FOV), the algorithm identifies the correct section of sky on 99.7% of the sensor orientations where spatial accuracy of the imaged star is 1 pixel (56.25 arc seconds) in standard deviation and the apparent brightness deviates by 0.4 units stellar magnitude. This compares very favorably with other algorithms in the literature.     

GMM-based target classification for ground surveillance Doppler radar

An automatic target recognition (ATR) algorithm, based on greedy learning of Gaussian mixture model (GMM) is developed. The GMMs were obtained for a wide range of ground surveillance radar targets such as walking person(s), tracked or wheeled vehicles, animals, and clutter. Maximum-likelihood (ML) and majority-voting decision schemes were applied to these models for target classification. The corresponding classifiers were trained and tested using distinct databases of target echoes, recorded by ground surveillance radar. ML and majority-voting classifiers obtained classification rates of 88% and 96%, correspondingly. Both classifiers outperform trained human operators.     

Development of airborne moving target radar for long range surveillance

The following topics are discussed in the context of the development of an airborne moving target radar for long range surveillance: US Navy long range shipborne radar; Cadillac I airborne early warning (AEW) radar; Cadillac II airborne early warning (AEW) radar; airborne moving target indicating (AMTI) radar; related post-war radar activities; and the invention of the displaced center antenna. Among the topics studied is the use of a monopulse antenna in an MTI radar to remove the degradation of the MTI caused by rapid scanning of the antenna. A method of using a monopulse antenna for motion compensation in airborne MTI is discussed.<>     

一种用于深空自主无线电的码速率估计算法

针对深空自主无线电的码速率盲估计问题,在码元起始位置未知的情况下,通过对估计误差的理论分析,提出一种改进的基于分离符号矩估计(SSME)的码速率估计算法,设计分区估计信噪比(SNR)并进行比较选大的方法,以保证码速率估计的精度。同时对该算法的计算复杂度进行定量分析,并与传统单次延迟相乘法、改进的多次累加延迟相乘法进行比较。仿真结果表明,本文算法能够有效完成低SNR条件下的码速率估计,其误估计概率明显优于单次延迟相乘法,与多次累加延迟相乘法相当,但计算复杂度不到多次累加延迟相乘法的10%。     

A nonlinear IMM algorithm for maneuvering target tracking

In target tracking, the measurement noise is usually assumed to be Gaussian. However, the Gaussian modeling of the noise may not be true. Noise can be non-Gaussian. The non-Gaussian noise arising in a radar system is known as glint noise. The distribution of glint noise is long tailed and will seriously affect the tracking performance. We develop a new algorithm that can effectively track a maneuvering target in the glint environment The algorithm incorporates the nonlinear Masreliez filter into the interactive multiple model (IMM) method. Simulations demonstrate the superiority of the new algorithm     

Satellite intercept targeting DSP algorithm design and evaluation

A unified processing approach for the detection and localization of satellites or other exoatmospheric targets is presented. Enhanced filtering and centroid determination algorithms were developed based on real-time implementation constraints, mission conditions including accuracy requirements, and signature structure. The signature structure consisted of target returns, high-frequency random noise, low-frequency structured noise, and contamination sources resulting from debris and cosmic events. Detailed signal processing analyses were performed to verify the required subsample accuracy and the sensitivity to hardware and system constraints. The resultant system design was functionally verified in a real-time breadboard processor     

飞行小目标自适应双波门跟踪算法

波门跟踪是一种利用实际图像处理的区域范围的视觉跟踪算法。在飞行小目标信噪比较低的情况下,现有方法往往不能获得稳定的跟踪结果。针对小目标跟踪的特点,提出了一种自适应双波门的跟踪算法。该算法采用帧间差分算法检测小目标,通过质心标定修正当前帧目标的初始位置,并利用最小二乘估计预测算法实现目标范围的估计,从而实现自适应跟踪的目的。实验结果表明,即使在飞行小目标被短时遮挡情况下,利用本算法也能稳定地检测出它的位置,能根据目标的轮廓自适应地确定目标波门形状,并能有效解决目标跟踪偏移和短时丢失等问题。     

Modified multiple sample correlation algorithm for electronic target location

This research proposes a modification to the Multiple Sample Correlation Algorithm (MSCA) where some statistical concepts are aggregated to the original method. With our modifications we were able to improve the emidtter position fix estimate more than 240% compared to the original MSCA and more than 1,200% compared to the Extended Kalman Filter Methodology.     

基于非等距偏置的纤维铺放路径规划算法

复合材料由于其高比强度、高比刚度、耐烧蚀、抗侵蚀等一系列优点,广泛地应用于航空、航天、汽车等领域。纤维铺放是实现复合材料成型的主要方法之一,同时也是近年来发展最快、最有效的先进制造技术。为实现构件(特别是复杂结构件)的成型制造,必须将材料精确地铺放到芯模表面。针对上述问题,根据微分几何理论提出了一种面向复杂曲面的路径规划算法。在确定压辊位置和方向的前提下,利用平面-曲面求交构造初始路径,并通过非等距偏置以获得覆盖整个芯模的全部路径。该方法所生成的压辊路径,不仅可使纤维完全贴合到芯模表面,还包含了铺放系统所需的丝数信息,理论上实现了构件的精确铺放成型。通过在MATLAB中进行路径仿真,验证了所提纤维铺放路径规划算法的正确性与有效性。     

Passive ionosonde operation algorithm and technique for evaluating high-frequency band communication quality

An algorithm for operation of a new software-hardware complex to be meant for evaluating the information and technical characteristics of the bandlimited communication systems operating in the high-frequency band is presented. The algorithm makes it possible to evaluate jamresistant radio-channels in the aeronautical, marine, and other long-range radio links using the data on their passive oblique sounding by linear FM signals.     

基于自适应遗传算法的航迹规划研究

对传统遗传算法进行了改进,通过采用交叉概率和变异概率的自适应设计,避免了进化过程中固定的交叉概率和变异概率产生的个体早熟和收敛缓慢的现象。仿真算例结果表明,自适应遗传算法能够有效地提高遗传算法的全局寻优能力,加快算法的收敛速度,有较强的地形和威胁回避能力,可为低空突防飞行器提供满足战术要求的参考航迹。     

A LODBO algorithm for multi-UAV search and rescue path planning in disaster areas

In disaster relief operations, multiple UAVs can be used to search for trapped people. In recent years, many researchers have proposed machine le arning-based algorithms, sampling-based algorithms, and heuristic algorithms to solve the problem of multi-UAV path planning. The Dung Beetle Optimization(DBO) algorithm has been widely applied due to its diverse search patterns in the above algorithms. However, the update strategies for the rolling and thieving dung beetles of the DBO algorithm are overly simplistic, potentially leading to an inability to fully explore the search space and a tendency to converge to local optima, thereby not guaranteeing the discovery of the optimal path. To address these issues, we propose an improved DBO algorithm guided by the Landmark Operator(LODBO). Specifically, we first use tent mapping to update the population strategy,which enables the algorithm to generate initial solutions with enhanced diversity within the search space. Second, we expand the search range of the rolling ball dung beetle by using the landmark factor. Finally, by using the adaptive factor that changes with the number of iterations., we improve the global search ability of the stealing dung beetle, making it more likely to escape from local optima. To verify the effectiveness of the proposed method, extensive simulation experiments are conducted, and the result shows that the LODBO algorithm can obtain the optimal path using the shortest time compared with the Genetic Algorithm(GA), the Gray Wolf Optimizer(GWO),the Whale Optimization Algorithm(WOA) and the original DBO algorithm in the disaster search and rescue task set.     

一种适用于机场场面MLAT监视系统的定位算法及其性能分析

与通常的三维目标不同,机场场面目标的高度是已知固定值,这点在设计应用于民用机场场面监视的无源多点时差定位(MLAT)系统时应予以考虑。基于机场场面目标及MLAT系统的特点,提出了一种改进的时差定位算法,该算法特别适合应用于场面监视的MLAT系统中。相比于传统的三维定位算法,该算法不但可以提高定位精度,还可增强系统的鲁棒性。给出了该改进时差定位算法的克拉美罗界(CRLB),并进一步推导出了该算法与三维定位算法精度之间的理论关系,从理论上证明了该算法的定位精度高于三维定位算法。与此同时,基于条件数理论还证明了该算法的鲁棒性优于三维定位算法。仿真实验及实测数据证明了所得结论的正确性和有效性。     

A multi-objective multi-memetic algorithm for network-wide conflict-free 4D flight trajectories planning

Under the demand of strategic air traffic flow management and the concept of trajectory based operations (TBO),the network-wide 4D flight trajectories planning (N4DFTP) problem has been investigated with the purpose of safely and efficiently allocating 4D trajectories (4DTs) (3D position and time) for all the flights in the whole airway network.Considering that the introduction of large-scale 4DTs inevitably increases the problem complexity,an efficient model for strategic level conflict management is developed in this paper.Specifically,a bi-objective N4DFTP problem that aims to minimize both potential conflicts and the trajectory cost is formulated.In consideration of the large-scale,high-complexity,and multi-objective characteristics of the N4DFTP problem,a multi-objective multi-memetic algorithm (MOMMA) that incorporates an evolutionary global search framework together with three problem-specific local search operators is implemented.It is capable of rapidly and effectively allocating 4DTs via rerouting,target time controlling,and flight level changing.Additionally,to balance the ability of exploitation and exploration of the algorithm,a special hybridization scheme is adopted for the integration of local and global search.Empirical studies using real air traffic data in China with different network complexities show that the pro posed MOMMA is effective to solve the N4DFTP problem.The solutions achieved are competitive for elaborate decision support under a TBO environment.     

Accurate and autonomous navigation for the ATV

The Automated Transfer Vehicle (ATV) is a European spacecraft intended to service the International Space Station (ISS). It is designed to perform automated phasing, approach, rendezvous and docking to the ISS, then departure and deorbitation manoeuvres. Such an automated rendezvous mission towards a manned facility raises severe performance and safety constraints for the vehicle, which are declined towards the on-board Navigation in terms of availability, accuracy and failure tolerance: the ATV shall be operational after any first failure and safe conditions shall be reached after a second failure. The whole ATV navigation system has been designed to fulfil these very stringent requirements. Based on fully redundant hardware, the navigation algorithms present optimal estimators and multi-layers Failure, Detection, Isolation and Recovery (FDIR) capabilities to ensure the continuity of the state vector in case of failure. Several functions provide state vectors estimations and health reports, according to the flight phase: the attitude and drift estimation function provides the vehicle absolute attitude and angular rate during the whole flight; for the far rendezvous, position and velocity relative to the ISS are estimated by the relative GPS navigation and a dedicated relative navigation with Videometer applies in close rendezvous, in the final approach. All these autonomous navigation functions offer nevertheless a high level of monitoring and control to the ATV Control Centre operators. Thus the ATV innovative navigation chain provides the high level of performance, robustness and autonomy required by modern spacecrafts involved in human programs, today in Earth orbit but also for future space exploration missions.     

基于并联机构的轻型自主爬行钻铆系统法向调姿算法

法向调姿是飞机部件自动化钻铆的技术基础,是提高制孔质量的技术保证。根据飞机装配自主爬行钻铆系统的功能需求分析,设计了一套基于并联机构法向调姿的轻型自主爬行钻铆系统,采用改进的Grubler-Kutzbach算法对其进行自由度分析,论证该系统符合法向调姿时所需的5自由度运动。搭建了法向检测及法向调姿数学模型,提出了在保证虚拟刀尖点位置不变的情况下末端执行器由初始状态调姿到期望的姿态时并联机构所需调整量的位置逆解算法和算例,并运用Matlab对算法进行算例验证。结果表明:法向调姿位置逆解算法正确,计算过程简单。     

机动飞行目标的数学模型与仿真算法研究

描述系统运动的状态方程所含的状态理越多,其数学模型就越准确,但其数字仿真时的算法实现也越困难。困此,采用“当前”统计模型建立机动飞行目标的空间运动方程,并结合桥函数级数理论求解,实现了对机动飞行目标稳定、准确、实时地仿真计算。以典型机动目标为例,进行了数字仿真,通过对各主要状态量的计算结果分析,验证了该方法的有效性。