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。     

A newly bio-inspired path planning algorithm for autonomous obstacle avoidance of UAV

In this paper, a bio-inspired path planning algorithm in 3D space is proposed. The algorithm imitates the basic mechanisms of plant growth, including phototropism, negative geotropism and branching. The algorithm proposed in this paper solves the dynamic obstacle avoidance path planning problem of Unmanned Aerial Vehicle (UAV) in the case of unknown environment maps. Compared with other path planning algorithms, the algorithm has the advantages of fast path planning speed and fewer route points, and can achieve the effect of low delay real-time path planning. The feasibility of the algorithm is verified in the Gazebo simulator based on the Robot Operating System (ROS) platform. Finally, an actual UAV autonomous obstacle avoidance path planning experimental platform is built, and a UAV obstacle avoidance path planning flight test is carried out based on this actual environment.     

基于IMMKF算法的ADS-B监视应用目标跟踪

目标跟踪是机载广播式自动相关监视（ADS-B）应用的基础功能,对提升航空器周边的弱机动民航飞机目标跟踪性能具有重要意义。提出一种基于交互式多模型卡尔曼滤波（IMMKF）算法的ADS-B 监视应用目标跟踪方法。首先,针对弱机动背景下的民航飞机的飞行特点,建立包含匀速模型和标准协同转弯模型的运动模型集,并对模型进行线性化近似;然后,将模型预测和ADS-B 状态矢量量测数据作为IMMKF 算法中多个并行卡尔曼滤波器的输入,进行并行滤波;最后,计算得到目标状态矢量的估计和模型近似概率,并作为下一次迭代的输入。结果表明：相比于基于匀速模型的卡尔曼滤波目标跟踪方法,IMMKF 方法的位置跟踪误差降低了59%,速度跟踪误差降低了77%,显著提升了状态估计性能,具备较高的跟踪精度、稳健性与计算效率,在ADS-B 监视应用中具有实际应用价值与借鉴意义。     

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。     

北斗三号系统卫星自主完好性监测技术

完好性对于全球卫星导航系统(GNSS)来说至关重要,关乎到其能否被放心应用。卫星自主完好性监测(SAIM)技术,是完好性监测技术发展的前沿趋势,国内外卫星导航系统均竞相发展。介绍了北斗三号系统SAIM技术设计与实现的重要意义,从功能设计和实现原理两个方面,阐述了北斗三号SAIM技术体制。针对SAIM实际在轨监测数据的正态分布特性服从程度和长期稳定性等问题,随机选取某一颗中圆轨道(MEO)卫星自2020年7月31日北斗三号系统正式开通服务以来至2021年7月31日连续1年期间的监测数据,得到真实在轨监测数据的分布特性。最后,提出了告警门限优化、分级告警策略设计、星历完好性自主监测等方面的后续发展必要性建议,旨在为北斗系统更好地为全球用户提供更优质的完好性服务提供参考。     

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 memetic algorithm for path planning of curvature-constrained UAVs performing surveillance of multiple ground targets

The problem of generating optimal paths for curvature-constrained unmanned aerial vehicles （UAVs） performing surveillance of multiple ground targets is addressed in this paper. UAVs are modeled as Dubins vehicles so that the constraints of UAVs＇ minimal turning radius can be taken into account. In view of the effective surveillance range of the sensors equipped on UAVs, the problem is formulated as a Dubins traveling salesman problem with neighborhood （DTSPN）. Considering its prohibitively high computational complexity, the Dubins paths in the sense of terminal heading relaxation are introduced to simplify the calculation of the Dubins distance, and a boundary-based encoding scheme is proposed to determine the visiting point of every target neighborhood. Then, an evolutionary algorithm is used to derive the optimal Dubins tour. To further enhance the quality of the solutions, a local search strategy based on approximate gradient is employed to improve the visiting points of target neighborhoods. Finally, by a minor modification to the individual encoding, the algorithm is easily extended to deal with other two more sophisticated DTSPN variants （multi-UAV scenario and multiple groups of targets scenario）. The performance of the algorithm is demonstrated through comparative experiments with other two state-of-the-art DTSPN algorithms identified in literature. Numerical simulations exhibit that the algorithm proposed in this paper can find high-quality solutions to the DTSPN with lower computational cost and produce significantly improved performance over the other algorithms.     

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.     

A grasp planning algorithm under uneven contact point distribution scenario for space non-cooperative target capture

The contact point configuration should be carefully chosen to ensure a stable capture,especially for the non-cooperative target capture mission using multi-armed spacecraft. In this work scenario, the contact points on the base and on the arms are distributed on the opposite side of the target. Otherwise, large forces will be needed. To cope with this problem, an uneven-oriented distribution union criterion is proposed. The union criterion contains a virtual symmetrical criterion and a geometry ...     

Radar maneuvering target tracking algorithm based on human cognition mechanism

Radar Maneuvering Targets Tracking(RMTT) in clutter is a quite challenging issue due to the errors in the models and the varying dynamics of the processes. Modern radar tracking system calls for the adaptive signal and data processing algorithm urgently to adapt the uncertainty of the environment. The mechanism of human cognition can help persons cope with the similar diffi-culties in visual tracking. Inspired by human cognition mechanism, a comprehensive method for RMTT is proposed. In the method, the model transition probability in Interacting Multiple Model(IMM) and the validation gate can be adjusted dynamically with target maneuver; the waveform in radar transmitter can vary with the perception of the environment. Experimental results in cluttered scenes show that the proposed algorithm is more accurate for perceiving the environment and targets, and the waveform selection algorithm is better than that with fixed waveform.     

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.<>     

反舰导弹航路规划的递推算法

为了减小武器系统的作战反应时间,针对具有航路规划功能的反舰导弹,总结了导弹进行航路规划所需满足的约束条件,提出一种信息处理量小、计算迅速的无威胁规避航路规划算法——递推算法。递推算法秉承导弹按预定攻击方向攻击目标所需导航点最少的原则,根据一定的假设条件,由目标位置开始,按攻击方向的反方向,依据平面几何理论,依次递推得到所有导航点位置,以及导弹在各导航点的转弯角度,直至发射点。仿真数据表明,由该算法得到的参考航路,相对较短且便于工程实现。     

Minimal submodel-set algorithm for maneuvering target tracking

The variable structure multiple model (VSMM) approach to the maneuvering target tracking problem is considered. A new VSMM design, the minimal submodel-set switching (MSMSS) algorithm for tracking a maneuvering target is presented. The MSMSS algorithm adaptively determines the minimal set of models from the total model set and uses this to perform multiple models (MM) estimation. In addition, an iterative MSMSS algorithm with improved maneuver detection and termination properties is developed. Simulations results demonstrate that, compared with a standard interacting MM (IMM), the proposed algorithms require significantly lower computation while maintaining similar tracking performance. Alternatively, for a computational load similar to IMM, the new algorithms display significantly improved performance.     

Moving target imaging algorithm for SAR data

A digital processing algorithm for fine-resolution imaging of synthetic aperture radar (SAR) moving targets is described. The targets may have any translational and rotational motion components relative to the data collection platform. The algorithm requires the presence of up to three prominent points in the image of the target; the signals from these points provide estimates of the unknown target motion parameters. Phase compensation and data formatting based on these estimates eliminate motion-induced phase errors. This algorithm has been implemented on a VAX computer and used to process both simulated and real SAR data of moving targets. Results obtained using the simulated data are presented     

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     

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.     

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。