The Space Attitude Control And Error Compensation Of Four-axis Rotating Frame

When the ship is sailing on the sea,the attitude of the ship is changing all the time because of ocean current and waves.These factors will decline the receiving efficiency of satellite antenna,even make the satellite antenna lose its signal.This paper analyzed the features of four-axis framework combining with the reality of sailing boat.And studied the control algorithms of four-axis framework.By analyzing the affections of friction,the paper proposed a method of friction compensation for the four-axis framework.And at last,design a four-axis framework.This thesis mainly completes the works as follows:Firstly,according to characteristics of the four-axis framework,the mathematical model is built from the inner framework to the outer framework.And at last,by analyzing it dynamics the articles established an integrated mathematical model of the four-axis framework.Due to the adjacent axis of it are orthogonal,so the axis coupling with each other stronger.So the thesis designed a decoupling method based on Lyapunov,and then tested it by MATLAB.Secondly,kinematics of it was analyzed according to the structural characteristics of the rotation axis framework.Then the paper proposed two attitude solution methods,and they are based on three axis and four axis.This paper compared the two methods by MATLAB.Finally,it select the elements based on the design of four-axis framework.Thirdly,this thesis analysis the system error.Taking the azimuth axis for example,the paper analyzes the impact of friction torque for motor low-speed characteristics and location tracking features.Then it designed feed-forward compensation control based on the model of static friction,and studied on the effect of friction compensation.And then,this thesis studied on control algorithms based on the subsystem that deduced before and the rotation angles of each axis.And it mainly studied fuzzy-PID control algorithm and sliding mode control algorithm,and compared the results of every control algorithm.By using simulink,two advanced algorithm designed separately simulated and compared with the traditional PID regulating algorithm,and show the good performance of the two advanced PID control algorithm.Finally,this paper made the four-axis framework,and introduced the major hardware and software.And at last it do some test to prove the designed four-axis is worked.By the test,we know that the control system of four-axis framework designed in the paper can make the received satellite signals when the ship is sailing meet the error requirement.