Design And Realization Of Correction Technology In Antenna Digital Guidance Tracking Of UAV

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.