| The maritime satellite relay communication system based on small buoy requires that the satellite pointing antenna in the buoy has the characteristics of low profile,small volume and light weight.Based on this situation,this thesis proposes a satellite signal automatic tracking control strategy satisfying four Level 4 sea condition.In this thesis,the whole development process is discussed in detail from the overall structure,software algorithm and hardware unit level.At the same time,the thesis also describes the simulation test results of the automatic tracking control strategy.The test results show that the proposed strategy can be applied to the relay communication buoy system under the Level 4 sea condition,which can support the communication buoy system to track satellite signal stably.The main research contents of this thesis are as follows:(1)First of all,using top-down design pattern,the appropriate system index is given according to the degree of wave impact fluctuation on the buoy under the Level4 sea condition,designing the overall method,and then by adopting the idea of modularization,the whole system is divided into specific modules,each module are introduced in the system's role as well as the matters need to pay attention in type selection,then provide detailed work flow of the whole strategy,make the system run orderly.(2)Then,it is discussed in detail from the software algorithm level,including the initial star search algorithm and stable tracking control algorithm.Software algorithm is the core content of this thesis,which directly determines the tracking performance of this system.The static star search formula of the initial star search algorithm is derived from the coordinate transformation method and plane geometry method,and it is proposed that a more accurate earth model can be established by introducing the curvature radius of the standard unitary circle to improve the pointing accuracy of the antenna.In order to analyze the influence of antenna disturbance,the carrier coordinate system is established,and the formula of antenna theory alignment algorithm under dynamic condition is derived.The effect of the missing roll Angle on the whole tracking algorithm is discussed in detail and the solution is given for the two-axis flat antenna.A feed-forward compensation method based on Kalman filter is proposed to solve the transmission delay and burr problems of inertial navigation unit measurement data,and the effectiveness of the method is proved by Matlab simulation.In the tracking control algorithm design,by comparing the advantages and disadvantages of all kinds of closed-loop tracking algorithm and combining with the actual project requirements,the conical scanning tracking algorithm is finally selected,and on the basis of traditional conical scanning tracking algorithm,the conical scanning tracking algorithm which can quickly adjust the center of the circle and the conical scanning tracking algorithm based on AGC threshold are improved.(3)Finally,the hardware modules are selected and tested,and the overall joint debugging is carried out.Firstly,the selection and specific parameters of each module are described in detail,and then the single board test and the combined test with the central control unit are carried out one by one.Joint debugging was carried out after all modules were tested without error,including initial star search test,cone scan tracking test,AGC closed-loop tracking test and stepper motor tracking test,etc.,and the experimental results basically reached the expectation.Referring to the relevant literature,this thesis discusses the performance evaluation index and error analysis of the "satcom on the move" system,and expounds the errors from servo system,and expounds the errors caused by the servo system,data signal delay jitter,sensor,antenna workmanlike aspects and gives the improvement measures.This thesis summarizes the research results and shortcomings,and technically gives improved work for supporting practical applications. |
PDF Full Text Request