Regarding the attitude tracking control of spacecraft,a second-order mathematical model of attitude control system based on error quaternion is established. Based on modern control theory,a state feedback controller based on error quaternion is designed to configure the poles of the attitude control system and realize the attitude stable tracking of spacecraft. The simulation results show that the state feedback controller can achieve high precision attitude tracking control of micro spacecraft.

In this paper, the fault modes of liquid rocket engine are reviewed, and the latest achievements of liquid rocket engine fault diagnosis technology at home and abroad are analyzed in recent years, including the fault diagnosis based on the models, the signal analysis and the artificial intelligence. The application progress and the diagnosis effect of the different kinds of fault diagnosis methods are compared, and the future development tendency of fault diagnosis methods for liquid rocket engine is prospected.

According to the large lift-drag ratio and strong lateral reentry maneuverability of lifting reentry vehicle, a design method for the minimum-time deorbit point is proposed, which involves the landing position, return time and deorbit burnup constraints for consideration. Firstly, the minimum lateral distance between the landing site and the ground track is solved under the given conditions of the vehicle's orbit and landing position. By considering the position and time constraints, the reentry range angle and reentry time range are determined according to the parameters of reentry landing footprint. Secondly, under the fuel consumption constraint, the analytical calculation method of the deorbit range angle and time for given reentry angle is derived, and the value range of the two is solved by Newton's iteration method. Finally, the deorbit window is determined according to the range angle in deorbit and reentry stage, and the minimum-time deorbit point is solved by nonlinear optimization method. Numerical simulation shows that the shortest deorbit time calculation can be achieved by using this method under multiple constraints, which has good adaptability and can serve as a reference for spacecraft deorbit design.

The control performance of multi-stage platform system is studied under the influence of additional connection between satellite and payload. Firstly, the Newton-Euler method is used to establish satellite-payload multi-stage dynamic system, which creates the dynamic foundation for analyzing the influence of cable connection. And then, cable connection is regarded as additional s.jpgfness, and the multi-stage dynamic model of satellite is established with additional connection in this paper. Payload vibration isolation ability is analyzed on both close-loop and open-loop with and without additional s.jpgfness. Stability and pointing accuracy are also studied for active steering and ultra-quiet platform(ASQP)with additional s.jpgfness. Some suggestions are proposed to attenuate this phenomenon. The simulation result shows that additional connection slightly degrades the vibration isolation ability and lowers the stability of payload but the influence on pointing accuracy is weak.

The perturbation evolution laws of low, medium and high orbital heights are analyzed. Regarding two typical heterogeneous constellations, the optimal offset calculation method of orbit deployment and the constellation configuration keeping control strategy are designed. Examples show that the optimal coordination of heterogeneous constellation satellites can be realized using orbit development bias and perturbation motion keeping control.

A continuous spatial domain method is used when modeling the flexible spacecraft dynamics, taking into account the global large overall rigid-body motions and local elastic vibration with finite extension and bending, as well as the controlled inputs acting at boundaries, to exactly depict the strain hardening. Then, regarding thrusters and control moment gyros equipped at boundaries, a boundary damping algorithm based on dissipativity is proposed to stabilize the attitude and to damp out the vibration in presence of strain hardening. The result of numerical simulations shows the validity of the controller.

An unscented Kalman filter relative navigation method based on relative orbital elements is introduced to achieve continual navigation results of spacecraft formation with orbit maneuver for structure preserving or reconfiguration. By taking advantage of relative measuring information and maneuver acceleration information, the Gauss perturbation equation is adopt to establish the state transition equation of state variables and high dimensional observation equation, which makes the orbit maneuver well tracked.The UKF algorithm is used for consideration of such high nonlinear dynamic. The shortages of classical relative navigation method based on Hill equation or reduced relative orbital elements can be overcome by using this method. The orbit maneuver against relative motion influence can be tracked by using this method and continual navigation results needed by control strategy are showed.

During the misssion of gravitational wave detection, the dynamic attitude planning method of the gravitational wave detection satellite is proposed for the problems of dynamic changes of the target attitude and complex attitude maneuver constraints during the large-scale laser chain building. Firstly, the optimal target attitude solution method of the gravitational wave detection satellite is developed, and then the random node heuristic expansion method and the real-time update method of the target attitude are designed to smooth the moment trajectory and realize the dynamic target attitude planning. The simulation results show that the proposed method has higher pointing accuracy and consumes less energy, which is compared with the classical RRT attitude planning method and can meets the mission requirements of large-scale chain building and maintaining of gravitational wave detection satellites.

Aiming at the attitude control problem in the case of faults and multi-disturbances in the reentry section of the launch vehicle, a refine anti-disturbance fault-tolerant control method is proposed by using some known disturbance information. Firstly, the attitude control model of the vehicle including faults and multi-disturbances is established, and then the elastic vibration disturbance model is established. Secondly, a disturbance observer is designed to accurately estimate the model uncertainty in kinematics. Then, based on the idea of enhanced anti-disturbance control, a disturbance observer is designed to estimate the elastic vibration disturbance, and an extended state observer is designed to estimate the fault and other disturbances. Finally, using the output of each observer and based on the dynamic surface control, a virtual control signal is designed to dynamically compensate the uncertainty of the model mismatched channel. A refine anti-disturbance fault-tolerant controller is designed to compensate the fault and multi-disturbances to ensure the accuracy of attitude tracking. Simulation results show the effectiveness of this method which can effectively improves the attitude tracking precision and system reliability and achieves the effect of fine attitude control.

Aiming at the great disturbance to satellite attitude caused by the rapidly rotation of the turntable, in order to maintain the high accuracy of satellite attitude, two schemes are proposed. Firstly, schemes are about the trajectory planning of the sub-satellite points that are pointed by the wave beam of payload on turntable. Using the Archimedes spiral to plan the trajectory can make the turntable's rotation angle and velocity changes smoothly and slowly so that the disturbance torque to satellite body is reduced. Secondly, according to the motion information from the trajectory, based on the accurate dynamic model of the turntable, the disturbance torques are calculated and compensated synchronously with the turntable motion as the feed-forward control torque of controller output. With the cooperation of high-bandwidth feedback control, a composite controller is formed. The simulation verifies the effectiveness of the above schemes.

The UAV formation control method based on consistency algorithm and pilot following method is applied to study the multi-dimensional cooperation of time, space and attitude in the process of multi UAV formation flying mission. Based on the pilot following method, the UAV is divided into pilot aircraft and follower random, and the pilot aircraft and follower random together form a UAV formation. On this basis, the UAV kinematics model and formation controller based on consistency algorithm are designed. The UAV formation flight control system is deployed to control multiple UAVs for performing cooperative detection formation flight mission. Finally, three UAVs are used to carry out flight experiments, which verifies the effectiveness of the formation flight control method and provides support for the use of UAV simulation satellites to test spaceborne payload equipment.