Modeling And Simulation Of Satellite Dynamics And Attitude Control System Based On Modelica

With the development of aerospace science and technology,the tasks of satellites have become diversified,some equipment needs to maintain a certain rotation speed,which means that the satellites need to carry a rotating load cabin with a large mass.However,because of the influence of the actual factors such as the manufacturing process and installation deviation,the load cabin will have an unbalanced mass distribution,and the interference torque will be brought to the satellite when load cabin rotates,which will affect the stability of the satellite attitude.This article aims to model and simulate the satellite with large mass rotating load cabin based on the multi-domain modeling language Modelica,to study the dynamic coupling and attitude control problems between the satellite load cabin and platform cabin.Firstly,the space coordinate system,the attitude description of satellite and the structure of satellite dynamics and attitude control system are introduced.Then based on the idea of model reuse and easy expansion,the organization structure of satellite Modelica model is designed.And the Modelica models of satellite platform cabin,load cabin,balance wheel,reaction flywheel,error quaternion controller and sensor are built,according to the working principle of each basic component.And the unbalance parameters of the satellite dynamics components can be conveniently set,which lays a foundation for the subsequent system-level model construction.Secondly,based on the basic satellite Modelica models,a dynamic system model of a certain type of satellite is established,to study the influence of unbalanced load cabin rotation on the attitude of platform cabin.And then,the dynamic characteristics of the platform cabin under the condition of normal and failure of balance wheel are compared,so that the working effect of balance wheel is verified.Then the cases of load cabin’ speed with noise interference,installation with center of mass deviation,rotation axis deviation are studied.It is shown that the long-term rotation of the load cabin will bring the accumulated attitude deviation to the platform cabin.And the axis deviation has a great influence on platform cabin dynamics,which will cause unstable of platform cabin attitude in serious cases.Finally,based on the satellite Modelica dynamics model and the basic models,the closed loop of attitude control system model of the satellite is built,which can realize the maneuver from the initial attitude to the desired attitude.And the controller parameters are tuned and optimized to improve the response speed and control accuracy of the system.Then the validity and accuracy of the attitude control system under the conditions of load cabin rotation,noise interference,center of mass deviation and axis deviation are simulated and verified.Subsequently,the fault simulation is carried out under the two conditions,which are a single flywheel failure and the control signal distribution correction after the failure,to verify the reliability of satellite attitude control system.