Enter The Application Molding In Flexible Spacecraft Maneuver Control

Vibration of modern spacecraft’s large flexible appendages is always excited during large angle attitude maneuver, which will not only influenced the stability of the attitude seriously, but also may damage the appendages. Therefore, the vibration suppression is the most important problem that must be solved in the flexible spacecraft attitude control. In this paper, the attitude control for flexible spacecraft rapid and steady maneuver is studied, and the main contents are as follows.Single axis attitude dynamics model of the flexible spacecraft is established, and input shaping technology is introduced in the flexible spacecraft attitude control system to design a feedforward controller. Considering the influence of the coupled parameters of the closed loop system, a multiple mode input shaper is designed utilizing the whole closed-loop vibration frequency and damping ratio, and an active vibration restrain scheme based on input shaping technology in conjunction with feedback control is employed. The simulation results show that this closed-loop input shaper can suppress the vibration of the flexible attachment and reduce the attitude maneuver time much more effectively.In order to ensure the stability of spacecraft attitude and reduce the delay caused by the input shaper, an optimization control method based on input shaping is proposed by taking the relationship between various parameters of control system and the closed loop modal parameters into account. An input shaper is designed for flexible modes of closed loop system to suppress the flexible appendages’vibration, as well as, an optimization performance index consisting of maneuver time, stabilization time and modal vibration energy is given for a chosen rigid-body’s damping ratio of closed loop system and optimizing feedback control parameters, which improves the stability of rigid body motion. Simulation results show that the performance of flexible spacecraft attitude maneuver can be improved greatly with the method.Aiming at suppressing the vibration of flexible appendages excited by jet switch action during moving-to-rest large angle maneuver of spacecraft using jet and fly wheel as actuators, a ZVMM (Zero Vibration for Moving-to-rest Maneuver) shaper is designed to shape the jet command under the Bang-Bang control law. In order to further suppress the vibration excited by the abrupt change of the modal parameters during the jet process, a novel approach including the ZVMM shaper and parameter identification was proposed to shape the jet command additionally. To improve the control precision after the attitude maneuver, the actuator is switched to flywheel to output continous torque and a variable structure control law was applied for stability control. Simulation results demonstrate the proposed approach can not only complete moving-to-rest large angle attitude maneuver rapidly and steady, but also suppress the vibration excited by the abrupt change of the modal parameters.The differences of the input shaper and digital filter on the vibration suppression and control performance are both studied comparatively. The Chebyshev low-pass digital based on IIR filter is designed for reference instruction filtering, and the attitude angle acceleration spectrum got by the two methods is analyzed respectively. The simulation results show that the input shaper and digital filter both have good effect in restraining the vibration of the flexible appendages, but the input shape is superior to the digital filter on the stability and steady-state accuracy.