Research On Spacecraft Large Angle Attitude Sliding Mode Control

When the spacecraft maneuvering in a large-angle attitude,the attitude control system presents the characteristics of nonlinearity and strong coupling.It is very complicated to applied the existing linearized optimal control method in the spacecraft attitude control system directly.Besides,taking into account the increasing number of the flexible attachments carried by the actual spacecraft,the low-order mode vibration of flexible attachments caused an important impact on the attitude motion of the spacecraft.These factors pose a great challenge to the spacecraft’s performance and accuracy of control.In this paper,the spacecraft attitude maneuver control issues is studied in depth,including the following aspects:First,in view of the shortest time optimization of spacecraft maneuver in highangle attitude,a research on near-optimal sliding mode control of spacecraft attitude system is carried out.The global linearization method based on the tensor product model transformation is used to realize the spacecraft attitude control system.Then the near-optimal attitude maneuver control law of the spacecraft is designed using the linear quadratic regulator(LQR)optimal control method.So as to reduce the complexity of designing the attitude controller by directly applying the linear optimal control method.Combined with the global sliding mode control technique,the controller which combines the global sliding mode control law and the near optimal control law which is obtained through the tensor product model transformation is designed.So that the spacecraft attitude control system has the advantages of fast response,strong robustness and small on-line calculation.The simulation results show the effectiveness of the designed method.Secondly,aiming at the negative influence of the flexible attachment vibration on the spacecraft attitude movement,a vibration suppression control method for the flexible spacecraft is carried out.The input shaping device is used to design the active vibration suppression controller of attitude control system.On the other hand,sliding mode control is difficult to obtain the switching gain due to external torque disturbance and moment of inertia uncertainties.An adaptive integral sliding mode attitude control law based on input shaping is designed in this paper.Then,the stability of spacecraft attitude control system is proved by Lyapunov stability criterion.Then the simulation analysis of the designed method is carried out in this paper.Finally,in order to verify the effectiveness of the control method designed in this paper,a single-axis air bearing test platform is built.Then,the attitude control method proposed in this paper is applied to the attitude control system of single-axis flotation platform.The experimental results show that the designed attitude control strategy could guarantee the high dynamic performance and control precision.What’s more,the results are in good agreement with the numerical simulation.