调频步进雷达扩展目标运动补偿研究

本文首先对扩展目标的一维距离像进行了离散建模,然后给出了扩展目标调频步进雷达回波信号的数学模型,深入分析了径向运动对一维距离像的影响,推导得到了运动补偿的精度要求。研究了时域相关法与最小脉组误差准则,提出了一种适合工程需要的运动补偿算法。最后,进行了计算机仿真实验,证明了本文的结论。     

基于AJTF的ISAR成像算法研究

自适应联合时间-频率（AJTF）分析是一种被证实了的基于刚体目标二维运动模型的逆合成孔径雷达（ISAR）成像算法,但它在进行运动补偿参数搜索时使用的穷尽搜索方法收敛不稳定且计算量较大。介绍了一种改进的AJTF算法,它用粒子群优化方法进行运动补偿参数的搜索,提高了算法的稳定性和效率。仿真结果证明了该算法的优越性。     

一种空基雷达高速微弱机动目标信号相参积累方法

通过分析空基雷达对空目标检测时的简化运动模型,提出了一种基于时频反转互相关的方法来同时校正奇数次运动项带来的距离徙动和偶数次运动项带来的多普勒徙动。对于急动度较大的三阶运动模型,在此方法的基础上进一步提出了对称时移双重自相关处理的方法来估计得到急动度信息,通过其构建补偿函数来消除急动度带来的多普勒扩散。该方法无需进行参数搜索,计算量较小,可以适用高阶运动模型,实验验证积累效果较好。算法具有较好的工程应用前景,可推广应用到其他高速飞行器低可检测性场景下雷达回波信号的检测。     

BTT导弹增广比例导引律研究

比例导引规律相比于直接追踪法,跟踪精度有所提高,但是在目标机动性加大的情况下,传统比例导引规律制导精度仍不理想.因此,给出了三维空间导弹-目标追逃运动的空间矢量方程,建立了三维空间导弹-目标追逃运动模型,并基于李雅普诺夫稳定性理论,设计增广比例导引律(APNG).即在比例制导规律基础上,引入目标加速度补偿项来克服目标加速度对制导精度的影响.将该方法运用于机动目标的跟踪,仿真结果表明了增广比例导引律相比于传统比例导引律,制导精度高,脱靶量低,制导飞行时间短,制导性能有极大的提高.     

调频步进雷达扩展目标高分辨距离像分析

本文首先对扩展目标的一维距离像进行了离散建模;然后给出了扩展目标调频步进雷达回波信号的数学模型,证明了调频步进雷达相参合成扩展目标一维距离像原理;文章分析了目标运动对合成距离像的影响,推导了运动目标合成距离像的距离单元走动计算公式,给出了运动目标一维距离像二次相位误差补偿的速度临界值;最后给出了计算机仿真,证明了本文的结论.     

端射阵机载雷达距离模糊非平稳杂波补偿方法

端射阵天线是指波束指向垂直于阵列法线方向的一类特殊雷达天线,由于其具有低剖面和定向辐射特性,因而特别适合用于机载雷达的补盲.由于端射阵通常呈前视放置,因而与传统前视侧射阵机载雷达一样,不可避免地要面临杂波的距离非平稳问题.本文基于端射阵机载雷达杂波谱特性,提出了一种距离模糊下端射阵近程杂波补偿新方法.该方法以最远可检测距离单元为参考单元并增加了动目标约束保护条件,克服了存在距离模糊时基于杂波谱配准（Registration-Based Compensation,RBC）原理的传统补偿方法存在的目标相消以及计算量大的问题;同时针对可能存在的目标约束失配问题,进一步提出了基于虚拟波束的扩展补偿方法.计算机仿真结果验证了本文方法的有效性.     

基于非理想运动误差补偿的SAR地面运动目标成像(英文)

传统的SAR地面运动目标成像算法主要集中在距离徙动校正和目标的运动参数估计上.但在SAR实测数据处理中,非理想运动误差补偿对动目标聚焦成像质量至关重要,而且该误差既不能通过固定的SAR运动误差补偿算法来补偿,也无法通过采用自聚焦技术解决.该文根据含有非理想运动误差的SAR运动目标回波信号模型,对影响动目标多普勒中心的两类非理想运动误差进行深入分析,提出一种将INS惯导数据与距离走动轨迹相结合的非理想运动误差补偿算法,并通过实际数据和计算机仿真数据验证了该算法的有效性.      

基于恒加速度模型的斜视SAR成像CA-ECS算法

针对空载SAR俯冲模式下的高精度运动补偿方法进行研究,推导了恒加速度运动条件下的等效斜视距离模型,基于该模型推导出Extend Chirp Scaling相位补偿因子的数学表达式,提出了一种CA-ECS(Constant Acceleration ECS)算法.该算法的相位补偿因子包含多个方向速度和加速度参数,能够实现恒加速度条件下的运动补偿,是一种通用性强、适用面广的子孔径成像算法.计算机仿真结果表明本文使用的等效斜视距离模型的误差较小,CA-ECS算法能有效地完成加速度运动补偿.     

一种实时视轴跟踪的IRST系统像移补偿控制技术

针对面阵凝视器件运用到红外搜索跟踪(IRST)系统中出现的图像拖尾问题,为解决方位搜索转台变速运动下高质量的IRST系统像移补偿,提出一种实时视轴跟踪的IRST系统像移补偿控制技术。基于方位搜索转台速率实时感知的振镜高速、高精度控制策略,实现了对像移的准确补偿。采用高精度M/T测速算法实现了像移的准确计算,通过对振镜电机建立控制系统模型,开展了振镜补偿控制算法仿真研究。实验室成像测试结果表明,在方位搜索转台任意变速运动下,靶标成像清晰无拖尾,成像效果与凝视型几无差别。     

Modelling prostate motion for data fusion during image-guided interventions

There is growing clinical demand for image registration techniques that allow multimodal data fusion for accurate targeting of needle biopsy and ablative prostate cancer treatments. However, during procedures where transrectal ultrasound (TRUS) guidance is used, substantial gland deformation can occur due to TRUS probe pressure. In this paper, the ability of a statistical shape/motion model, trained using finite element simulations, to predict and compensate for this source of motion is investigated. Three-dimensional ultrasound images acquired on five patient prostates, before and after TRUS-probe-induced deformation, were registered using a nonrigid, surface-based method, and the accuracy of different deformation models compared. Registration using a statistical motion model was found to outperform alternative elastic deformation methods in terms of accuracy and robustness, and required substantially fewer target surface points to achieve a successful registration. The mean final target registration error (based on anatomical landmarks) using this method was 1.8 mm. We conclude that a statistical model of prostate deformation provides an accurate, rapid and robust means of predicting prostate deformation from sparse surface data, and is therefore well-suited to a number of interventional applications where there is a need for deformation compensation.     

前视扫描声呐成像径向误差分析和补偿

该文提出了一种基于运动补偿的前视扫描声呐成像方法:采用后向映射,将扇形成像区域的直角坐标系转换成极坐标系,在极坐标系进行2维插值,提取幅度并转成图像格式。通过建立载体运动模型,分析载体运动,将载体运动影响转换为图像域移动,对前视声呐图像进行实时运动补偿,消除径向误差。分析了“深海勇士”号前视声呐数据,其单幅图像最大径向误差近似达到工作距离的19%。通过仿真和实验验证所提算法补偿了由载体运动造成的图像的径向误差,能准确表示目标信息。     

步进频率雷达目标运动补偿方法研究

介绍了步进频率信号及目标运动对合成一维距离像的影响,分析步进频率雷达中目标运动补偿的思路,在此基础上提出应用最小脉组误差准则对步进频率信号进行速度补偿的方法,对该方法进行分析和仿真,证明该方法具有较高的实用价值.     

Options for airborne interferometric SAR motion compensation

Airborne interferometric SAR (InSAR) has the potential to provide topographic data with a precision of the order of one metre. However, to generate data accurate to this level it is essential to measure and compensate for nonlinear motion of the two antennas which constitute the interferometric baseline. Conventional motion compensation techniques are extended to the two-channel imaging scenario of InSAR. Phase compensation of both channels to the same reference track and compensation to two separate tracks are considered and modeled using point target simulation, and real InSAR data. The single track approach allows track segmentation to follow aircraft drifts without causing discontinuities in the differential phase, but is sensitive to range cell migration effects. The dual track approach is not sensitive to these errors but suffers from discontinuous differential phase at segmentation boundaries, which complicates the phase unwrapping process. A new formulation for each approach is presented that compensates for unknown terrain coupled with low frequency aircraft motion. In addition, a new approach that uses the dual track approach initially and then converts to a single reference track after compression is proposed. This realizes the benefits of both approaches with only a small increase in computation     

机载超宽带SAR运动补偿方法

本文基于机载合成孔径雷达（SAR）正弦运动误差模型,研究了机载超宽带SAR运动补偿方法。首先,本文从理论上解释了传统“两步运动补偿法”原理,并分析了“两步运动补偿法”的优势与不足。其次,基于分析结果,文中提出一种“两步运动补偿法”的改进处理流程,称为“单步运动补偿法”。在“单步运动补偿法”中,用于补偿距离空变相位误差的“二阶补偿”由在距离弯曲校正（RCMC）后的回波域内进行改为在RCMC前的回波域内进行。与原始“两步运动补偿法”相比,“单步运动补偿法”具有更好的高频运动误差补偿性能。文中详细推导了所提运动补偿方法,并通过仿真实验证明了该方法的有效性。      

ISAR成像处理中的一种运动补偿方法

运动补偿是ISAR成像的关键问题之一,通常都是利用目标的一个孤立点作基准进行补偿。实际目标不一定存在孤立点,本文提出了一种对连片目标回波运动补偿的新方法。     

Backward motion compensation for interlaced HDTV

The pel-recursive approach to motion estimation has been widely studied for compensating progressively scanned, moderate-resolution video. Although pel-recursive algorithms may not be suitable for application to interlaced high-definition television (HDTV), the underlying principle of backward motion compensation, upon which pel-recursive algorithms are based, can be exploited to improve the existing motion compensation algorithms. This paper proposes applying a backward approach to motion compensation to improve the performance of standard block-based algorithms for motion-compensated interlaced HDTV sequences. First, we describe a framework for motion compensation in which motion information is parameterized by a motion operator and a domain for that operator. Within this framework, we characterize the type of motion information represented by forward (e.g. block-based) and backward approaches to motion compensation. We propose a method for combining these two sources of motion information to form an optimal motion-compensated prediction. Simulations on two interlaced HDTV sequences demonstrate performance improvements between 1 and 2 dB over standard block-based methods.     

基于距离单元统计模型的ISAR包络对齐方法

包络对齐是逆合成孔径雷达（ISAR）平动补偿的关键技术之一。本文通过分析目标平动和转动对距离像的影响,建立了距离单元统计模型,并提出了一种基于该统计模型的包络对齐方法。该方法通过两个步骤完成包络对齐：利用目标回波数据提取各距离单元统计模型的参数;搜索使各距离单元的联合概率密度函数取得最大值的距离偏移量进行包络对齐。分析...     

基于参数化模型的空间目标一维距离像补偿技术

空间目标往往具有很高的速度,甚至还具有一定的加速度,回波信号经过去斜率处理后仍然是一个多分量的多项式相位信号,高阶相位使得目标的一维距离像产生畸变,脉冲压缩前必须进行运动补偿,否则无法得到正确的一维距离像。本文以平均距离像最小熵准则为基础,提出了一种基于测距元参数化模型的空间目标一维距离像畸变补偿技术。根据空间目标的运动特性,建立了目标测距元的参数化模型。结合雷达的宽窄带测元信息,以平均一维距离像的熵作为目标函数,建立了测距元模型参数估计的优化模型和算法,并利用该参数对一维距离像进行运动补偿。仿真结果验证了本文算法的有效性。      

TRBR: Flight body posture compensation for transverse ricochetal brachiation robot

Transverse ricochetal brachiation is a sophisticated locomotion style that mimics athletes swinging their bodies with their hands on a ledge in order to propel themselves for a leap to a target ledge. This paper describes the development of a transverse ricochetal brachiation robot (TRBR) and outlines motion control strategies for active flight body posture compensation. The crucial design parameters were obtained by formulating an optimization problem with the goal of maximizing flight distance. Shoulder joints with switchable stiffness were used to enable resonance excitation via the swinging of a robot tail during the swing phase, while enabling tight arm-and-body engagement during the flight phase. Novel electric grippers were designed to provide the required holding forces as well as quick-release functionality to ensure that the kinetic energy accumulated during the swing phase could be transferred smoothly to the flight phase. The reference trajectory of the robot tail was obtained using an optimization procedure based on a dynamic model of the swing phase. We also adopted a dynamic model for the flight phase to elucidate the effects of midair body rotation with the aim of developing body posture compensation methods. Simulation and experimental results demonstrate the efficacy of the proposed body posture compensation method based on a successive loop closure design in improving flight body posture during transverse ricochetal brachiation. The integration of arm swing motion with tail compensation also proved highly effective in enhancing hang time and travel distance.     

一种基于多普勒信息的雷达目标跟踪方法

机载预警雷达采用脉冲多普勒体制,具有良好的低空探测性能,但其存在不可忽略的多普勒盲区问题。在目标跟踪的过程中,该盲区容易造成目标中断和重起批。针对多普勒盲区条件下的目标连续跟踪问题,文中提出了一种基于多普勒预测的扩展卡尔曼滤波算法(Doppler Prediction EKF,DP-EKF),该方法将多普勒盲区的先验信息并入到扩展卡尔曼滤波算法中,通过状态预测判断目标在未来时刻是否落入多普勒盲区,从而自适应地调整跟踪滤波规则,解决多普勒盲区条件下目标连续跟踪问题。仿真结果表明,该算法对于运动模型已知的航迹不连续目标具有较好的跟踪效果,能够维持其航迹的连续性。