【作者】 张伟；

【导师】 张合； 王炅；

【作者基本信息】 南京理工大学 ， 机械工程， 2017， 博士

【摘要】 为了应对新型现代战场的需求,针对常规单兵火箭弹这类无控低速飞行器经过增程发射后落点散布大的问题,将原有的无控低速飞行器进行低成本制导化改造。其方式是把导弹中的弹道修正技术经过改造应用到单兵火箭弹等低速飞行器中,通过在飞行弹道上的一次或两次修正,减少无控低速飞行器的落点偏差,提高战场效费比。但是考虑到低速飞行器发射时需承受一定发射过载的特点,并考虑到低速飞行器口径较小,以及末段弹道不稳定的特性,因此不能直接照搬较成熟的导弹制导技术。另外,激光半主动目标方位探测技术具有抗电磁干扰能力强、目标定位精度高、成本低、速度快等优点,是解决无控低速飞行器制导化改造的成本与制导精度之间矛盾的一种可行途径。所以,研究低速飞行器用的激光半主动目标方位探测技术,对于加快常规低速飞行器低成本制导化的改造进程和新型制导低速飞行器的研制进程等方面具有重要的现实意义。本文以低速飞行器为对象,分析了低速飞行器激光半主动目标方位探测的工作过程;基于近地面环境的激光传输路径因素,研究了飞行器上激光探测系统捕获激光信号的能力;针对环境背景噪声和电路噪声,研究了四象限探测器的数字式测量精度;通过对低速飞行器弹道诸元的计算,研究了末段弹道特性对激光半主动目标方位探测系统的影响。具体的研究内容如下:确定了低速飞行器上的激光半主动目标探测系统为捷联式结构以及光学系统应采用折射式光学系统的总体结构。建立了四象限探测器目标方位偏差角的测量模型,并对测量算法误差进行了补偿。根据低速飞行器被动段六自由度弹道模型,研究了飞行器在末段弹道上的空间状态。建立了低速飞行器上激光半主动目标探测系统捕获的激光信号功率模型。利用双向反射分布函数概念,推导了激光半主动体制目标反射截面公式,计算并分析了目标表面为斜面时,在末段弹道不同目标斜面倾角条件的激光半主动体制目标反射截面。基于Mie散射理论,研究了战场气溶胶粒子群对激光半主动信号传输效率产生的影响。基于Gamma-Gamma大气湍流光强闪烁理论,研究了不同条件下低速飞行器上激光半主动探测系统接收激光信号的归一化功率概率密度函数。建立了激光半主动目标探测系统捕获的倒置抛物线型激光回波信号模型和泊松分布型环境背景噪声模型,基于泊松过程的光子捕获模式,推导了四象限探测器单象限捕获的激光脉冲峰值功率的克拉美罗下限计算公式。根据四象限探测器捕获的激光回波脉冲信号,建立了激光脉冲信号经过四象限探测器和跨阻放大器形成的理想电压信号模型,并基于高斯分布的电路白噪声模型,针对不同理想电压信号的波形、半峰宽度和系统总信噪比,利用蒙特卡罗方法研究了基于四象限探测器归一化和差算法数字式测量目标位置偏差角和目标方向偏差角的统计分布规律。建立了捷联式激光半主动目标探测系统的目标捕获域模型,研究了捷联式激光目标方位探测系统的最小视场角和最佳起始探测点。建立了理想的捷联式激光接收离焦光学系统模型,设计了大视场、短焦距的离焦折射式光学系统,并通过光学仿真,提出了光学系统误差的补偿方法。反向计算了捷联式激光半主动目标探测系统在末段全弹道测量的目标位置偏差角和目标方向偏差角,并提出了利用Savitzky-Golay 一阶平滑滤波算法提取准确的目标方位偏差信息的方法。针对低速飞行器弹道修正能力的局限性,通过分析在末段弹道上激光探测系统测量的目标方位偏差角的变化特性,设计了低速飞行器弹道修正的启控时机和方向。针对在末段弹道初、中期阶段,激光探测系统中的四象限探测器随飞行器绕纵轴旋转以及光斑中心远离四象限探测器光敏面中心的特点,提出了基于对下一探测时刻光斑中心预测的对单象限电路通道单独自适应增益的方法。根据系统要求,设计了捷联式激光半主动目标方位探测电路系统总体方案以及激光脉冲探测电路系统和脉冲信号采集处理系统等子电路系统。通过加工光学系统和电路系统,以平面靶板为目标,搭建了目标方位偏差角测试平台,完成激光回波探测实验、目标方位偏差角测量与统计实验。实验结果表明模拟式测量目标位置偏差角的精度优于0.2°。更多还原

【Abstract】 In order to meet the needs of the new modern battlefield,and considering the problem that the drop distribution scale of conventional low speed aircraft with no control method,such as the individual rocket,is large after extending the range of fire,the low cost guidance modification of the conventional low speed aircrafts needs to be conducted.The method is to apply the ballistic correction technology of the missile to the low speed aircraft and reduce the drop distribution scale of them by one or two corrections in the flight trajectory,and improving the battlefield efficiency.However,taking the small caliber and a certain launch overload restriction of the low speed aircraft into account,as well as the instability characteristics of terminal trajectory,it cannot directly use the mature missile guidance technology.In addition,the semi-active laser target detection and guidance technology has the advantages of strong anti-electromagnetic interference ability,high target positioning accuracy,low cost and fast speed,which is a feasible solution to the contradiction between the cost and guidance precision of the uncontrolled low speed aircraft.Therefore,it is of great practical significance to study the target detection technology based on semi-active laser for low speed aircraft,which is of great significance to speed up the low cost guidance modification process of conventional low speed aircraft,and the development of new low speed guided aircraft.In this paper,the low speed aircraft is the object of study,and the process of semi-active laser target azimuth detection is studied.Based on the ground transmission environment of the laser,the ability of the laser detection system to capture the laser signal is studied.For the background noise and the circuit noise,the measurement accuracy of quadrant photodectector is studied.The influence of terminal trajectory characteristics on the semi-active laser detection system is studied by calculating the trajectory of the low speed aircraft.The specific research contents are as follows:The target detection system structure for the low speed aircraft is defined to the strapdown type,and the optical system structure is defined to the refraction type.The measurement model of the azimuth deviation angle of the quadrant photodetector is established,and the influence of the quadrant photodetector deadband on the measurement is studied.According to the six degree of freedom trajectory model of the low speed aircraft,the spatial state of the aircraft on the terminal trajectory is analysed.The power equation of the laser signal captured by the optical system of the semi-active laser target detection system is proposed.Based on the concept of bidirectional reflection distribution function,the reflection cross section formula of semi-active laser system is deduced.The influence of different slope angle and different laser reflection angle on the target reflection cross section is calculated and analyzed,when the target surface is inclined.Based on the theory of Mie scattering,the transmission efficiency of aerosol particles on laser transmission path is studied.Based on the Gamma-Gamma atmospheric turbulence theory,the intensity fluctuation effect of the strong ground turbulence field on the laser signal captured by the laser detection system is studied.The models of inverted parabolic laser signal and Poisson distribution environment background noises captured by the semi-active laser target detection system are established,and based on the Poisson photon capture mode,the Cramer-Rao lower bounds of laser pulse peak power in single quadrant of the quadrant photodetector are generated.Based on the laser pulse signal captured by the quadrant photodetector,the model of ideal voltage pulse signal produced by the transimpedance amplifier is established.Considering the white noise model of the circuit that obeys the Gaussian distribution,the statistical distributions of the target position deviation angle and the target direction deviation angle calculated by the normalized sum-difference algorithm of quadrant photodetector are studied based on Monte Carlo method,under the conditions of different signal distribution types in the time domain,different ideal signal widths at half maximum and different signal to noise ratios.The model of target capture domain for the semi-active laser detection system is established,and the optimal field of view angle and the optimal starting trajectory point for the target detection are studied.The ideal defocused optical system model of the strapdown laser detection system is established,and a defocused optical system with large field of view and short focal length is designed.The error compensation method for the optical system is studied by optical simulations.The target position deviation angle and the target direction deviation angle of the strapdown semi-active laser detection system in terminal trajectory are calculated reversely,and the accurate azimuth deviation information is extracted by the mothod of Savitzky-Golay first order smoothing filter.Considering the limitation of the trajectory correction capability of the low speed aircraft,the moment and direction of the trajectory correction of the low speed aircraft are designed by analyzing the variation characteristics of the target azimuth deviation angle calculated by the strapdown laser detection system in terminal trajectory.Considering the characteristics that the quadrant photodetector is rotating with the aircraft longitudinal axis and spots’ centers are far away from the center of the quadrant photodetector in the early and middle terminal trajectory,the programmable gain method for single quadrant circuit channel is proposed based on the prediction of the spot’s center at the next detection time.According to the system requirements,the overall system scheme of the strapdown semi-active laser target detection circuit and the sub circuit systems such as the pulsed laser detection circuit system and the pulsed signal acquisition and processing system are designed.The optical system and the circuit system are processed,and a plane target is set as the target,so the test platform for detecting target azimuth deviation angle is set up.The echoed laser detection experiment,the target azimuth deviation angle measurement and statistical experiment are conducted.The experimental results show that the analogue measurement accuracy of target position deviation angle is better than 0.2°.更多还原