Finite-time Attitude Tracking Control Design For Flexible Spacecraft

With the rapid development of space technology,the structure of spacecraft began to become more and more complex.In order to make the spacecraft complete more space exploration missions,a lot of flexible components,such as solar panels and satellite dishes have been added in modern spacecraft.These flexible components brings many new problems to the control of spacecraft.When the spacecraft in space to perform maneuvering tasks,flexible components caused by the elastic vibration,will weaken the spacecraft attitude control accuracy,even serious will lead to spacecraft instability.In addition,spacecraft in orbit will inevitably be affected by some disturbance torque,which will aggravate the elastic vibration caused by flexible components.In addition,many physical parameters of flexible spacecraft can not be accurately obtained,which will also bring difficulties to attitude control of such spacecraft.Based on flexible spacecraft as the research object,this paper aimed at the moment of inertia parameter uncertainties exist in the process of orbiting,the external environment disturbance and flexible attachment mode cannot be directly measured under the condition of the attitude tracking control problem of in-depth study,puts forward several new controller design method,the main research contents include:For flexible spacecraft with uncertain moment of inertia,unknown external interference and unmeasurable flexible mode,a kind of finite time controller is designed by using terminal sliding mode control method on the premise that the upper bound of interference is known.The finite time stability of the closed-loop system is proved by Lyapunov stability theory,and the feasibility and effectiveness of the controller are verified by a simulation example.For the flexible spacecraft with unknown upper boundary of external interference,the total interference is estimated by using the expanded state observer,and the estimated value is introduced into the controller to realize the compensation of the total interference.A kind of attitude tracking controller based on observer is designed by using terminal sliding mode control algorithm.Through the stability theory of Lyapunov,it is proved that the closed-loop system under the action of the controller can achieve convergence in a limited time,and the effectiveness and superiority of the controller is verified by simulation.Finally,on the basis of the previous studies,the possible actuator saturation phenomenon during the spacecraft operation is further considered.By applying the provided extended state observer design method and sliding mode control technique,a finite-time terminal sliding mode controller is developed to solve the attitude tracking control problem of the flexible spacecraft with the external environment disturbance,the moment of inertia parameter uncertainties and actuator saturation.In the same way,the validity of the controller is verified by simulation.