【作者】 张小龙；

【导师】 刘志镜； 文运丰；

【作者基本信息】 西安电子科技大学 ， 计算机技术， 2014， 硕士

【摘要】 本论文来源于某无人机测控系统的工程需求,目的是对地面定向测控天线数字引导跟踪过程中产生的方位和俯仰偏差进行修正补偿,实现对无人机的精确跟踪,从而解决地面测控站在利用数字引导方式跟踪目标无人机时,由于各种因素的影响,导致计算出的引导角度与实际目标跟踪的最优角度不一致,从而降低测控链路性能,对无人机的飞行安全和作战效能带来不利影响的问题。本论文从无人机测控链路的实际工作要求出发,结合相关理论知识,设计并实现了一种针对无人机测控链路定向天线数引角度计算误差补偿的处理方法。本文取得的主要研究成果包括:1.阐述了无人机测控系统目标跟踪的主要方式,分析了数字引导跟踪的工作原理,并对无人机数字引导跟踪中的误差现象进行了分类归纳,从中提取出了两类常见误差:滞后类误差和俯仰轴误差,并逐一分析了两类误差的产生机理;2.针对滞后类误差的产生原因,提出了相应的补偿方案,采用卡尔曼滤波外推预测算法,对数字引导跟踪中的系统时延进行补偿,并给出了具体的算法公式。通过对无人机地面定向天线在数字引导跟踪模式下的运动特性分析,建立了天线数字引导跟踪模型,并利用Matlab软件进行了仿真,验证了补偿方案的可行性;3.针对俯仰轴误差,从对大气环境、大气折射率计算、大气折射率模型描述等大气折射的基本知识出发,详细分析了无线电波大气折射效应对天线伺服数字引导跟踪的影响。利用球面大气中的斯奈尔定律,给出了大气折射的基本公式,在分析了常用的大气折射效应修正方法后,结合无人机测控的自身特点,选取基于地面参数预测的线性分层法,作为无人机数字引导跟踪俯仰轴误差的补偿算法,并提出了详细的补偿方案。利用无人机实际飞行的历史试验数据对方案进行了仿真计算,验证了补偿方案的可行性;4.在实际工程中,应用本文中提出的卡尔曼滤波外推预报算法,对系统延时240毫秒左右,数据刷新周期40毫秒的测控链路进行了6点外推预测。经实际飞行验证,在滞后类误差对数字引导跟踪影响最大的无人机起降阶段,补偿处理基本解决了因系统时延导致的数字引导跟踪滞后问题,实现了全程方位中心轴的目标对准,有效提高了无人机的飞行安全;5.在实际工程中,应用本文中提出的大气折射效应修正算法,对无人机俯仰数字引导角度进行了误差补偿。经实际飞行验证,补偿后数字引导跟踪下的测控链路信号强度明显好于不进行补偿的情况,补偿处理达到了预期的目的,有效增强了无人机远距离、低仰角情况下的链路信号强度,提高了链路的有效作用距离。目前,本文介绍的无人机数字引导跟踪误差补偿技术已经成功应用于多种无人机测控系统。多次的无人机实际飞行试验数据表明,误差补偿的功能、性能可靠性及补偿算法的运算开支均能满足工程要求,具备较高的推广价值。更多还原

【Abstract】 This paper derives from a project requirement of a aircraft TT&C(Tracking, telemetry and Command) system, and the research purpose of this paper is to correct azimuth and elevation deviation of the ground directional monitoring antenna generated during the process of Digital Guidance Tracking,to achieve accurate tracking of the UAV. ground control station so as to solve guide the way in the use of digital tracking target UAVs, due to various factors, resulting in optimum angle guidance angle computed inconsistent with the actual target tracking, thereby reducing monitoring link performance of UAV flight safety and adversely affect the operational performance issues. In this paper, Based on the actual requirements of UAV control link, combined with relevant theoretical knowledge, we design and implement a angle calculation error compensation approach for UAV TT&C system in the process of directional antenna digital guidance tracking. The main results obtained in this article include:1. Describes the main way to UAV TT&C system of target tracking, analyzes the working principle of digital guide track, and guide the UAV digital tracking errors phenomena classified summarized, extracted from the two types of common errors: time lag error and pitch axis error, and analyzes the generation mechanism of two kinds of error.2. Accroding to the reason of the time lag errors, this paper put forward the corresponding compensation scheme, using the Kalman filter extrapolation prediction algorithm for digital guide tracking system to compensate for the delay. The paper also given detailed algorithm formulas. Through the analysis of UAV ground directional antenna movement characteristics in the digital guidance tracking mode, this paper established the antenna digital guidance tracking model, and simulated it by using Matlab software. The result verified the feasibility of the compensation scheme.3. For the pitch axis error, using the basic knowledge of the atmosphere refraction(atmospheric environment, atmospheric refraction rate calculation, atmospheric refraction model description, for example), a detailed analysis of the effects of atmospheric refraction effect of radio waves on the antenna servo digital guidance tracking was given in this paper. Using spherical atmosphere Snell’s law, it also given the basic formula of atmospheric refraction. After the analysis of most commonly used correction method to the effect of atmosphere refraction, and the analysis of the inherent characteristics of the UAV monitoring, the paper selected the linear hierarchical method of ground-based parameter prediction, as digital guidance compensation algorithm of tracking error of pitch axis, and put forward a detailed compensation scheme also.Using historical flight data of drones, a simulationcalculation was made on the program, to verify the feasibility of the compensation scheme.4. In practical engineering, using the Kalman filtering extrapolation prediction algorithm presented in this paper, a 6-steps extrapolation forecast was applied to a TT&C system with a 240 ms time delay and a 40 ms data refresh frequency. Accroding to the result of actual flight experiment, in the UAV’s takeoff and landing stage, which the most impact of digital guidance tracking caused by time lag error happened,the compensation processing basically solved the digital guidance lag caused by the digital system delay. Through this data processing, An accurate tracking of the UAV was achieved, the safety of UAV flight was effectively improved also.5. In practical engineering, by ths application of atmospheric refraction effect correction algorithm presented in this paper, UAV pitch digital guidance angle error was compensated. Verified by actual flight conditions, the signal strength of the TT&C link with compensation is significantly better than without compensation, the compensation processing to achieve the desired purpose, Effectively strengthen the link single strength of UAV in Far Distance and low elevation condition, improve the effective distance of TT&C link.Currently, the error compensation technique has been successfully applied to a variety of UAV TT&C system. UAV actual flight experiment data repeatedly show that the error compensation function, performance, reliability and CPU occupancy rate uesd by compensation algorithm can meet the engineering requirements. The techmology has high value of popularization.更多还原