| Agile Satellite is receiving growing attention from researchers because of its strong attitude maneuver ability,efficient operation mode and wide application prospect,and it is an important trend of complex observation mission.Agile Satellite Maneuvering Imaging Mode is a complex mode,it can achieve continuous imaging of arbitrary surface track and will provide more application for energy field,territory and national security and national defense.Agile Maneuvering Imaging technology has a variety of complex requirements for the attitude control during maneuvers and imaging process,it concludes different constraint conditions in different stages.It has high requirement of attitude pointing accuracy and attitude angular velocity accuracy,proper attitude planning method and control strategy for agile maneuvering imaging should be designed to ensure that agile satellite can follow specific push-scanning mode to complete high precision imaging.Aiming at these above problems,the research of corresponding attitude maneuvers planning method is conducted to explore high precision attitude maneuvers planning method and support optimization design of agile platform in this paper.The main work of the research is as follows:(1)Attitude kinematics model,attitude dynamics model and orbit dynamics model are established according to agile satellite maneuver characteristics.Agile earth observing process is analyzed,take multi-segmented banded imaging task as the instance to carry out the work and research of attitude planning for agile maneuvering imaging mission.(2)A deep research about attitude planning problems of agile satellite attitude maneuvering process has been done aiming at its movement features and constraints,and the attitude maneuvers planning method that satisfied multitasking sequence is designed.Based on attitude/control integrated planning,under the constraints of limited attitude adjusting time and executive ability,proper change rate of angular position is planned.Meanwhile,considering the flexural vibration caused by nonzero maneuvering angular acceleration and taking planned track as input of agile control system,the corresponding optimal control parameters can be obtained.On the basis of present planning attitude track study,the tasks are divided more particularly,and considering the constraints of nonzero initial/terminal attitude angle and attitude angle velocity,the related mathematical simulation about the designed planning method has been done.The simulation results show that the proposed track planning method has a certain inhibitory effect,and the proposed attitude planning method can solve three kinds of practical track application problems.(3)Aiming at the attitude motion requirement of agile satellite maneuvering imagingprocess,the constrains influencing imaging quality are analyzed,some deep research of push-scanning imaging planning for banded targets has been done.Considering that maneuvering imaging need agile satellite to complete imaging mission during attitude maneuvering process,attitude adjustment is more agile than traditional imaging satellite,but the imaging process is more complex,it should not only satisfy the constrains of observation time,observation area and photographic ground velocity simultaneously,also need to meet the attitude accuracy requirement.An attitude planning method of agile satellite during constant ground speed push-scanning mode has been proposed with considering drift angle influence to ensure the agile imaging accuracy.An optimized model is established to obtain the observation initial time of each band,and hence the lateral angular cumulative sum of satellite can be minimal during all imaging process.Meanwhile,the drift angle influence of agile active push-scanning has been considered during solutions,attitude angle and attitude angular velocity planning is done based on the constant ground velocity mode of earth push-scanning.Experiments show that the proposed imaging process attitude planning method can satisfy the requirement of agile imaging accuracy and solve the problem of drift angle compensation during maneuvering imaging.(4)Aiming at the problems of optimization goals that is energy/time optimum,open-loop control mode and the precision that cannot meet agile satellite accuracy requirement,the optimal planning based on pseudospectral method is described in detail,its advantages and characteristics are analyzed,and the subsection attitude planning scheme is proposed.In order to accomplish fast large angle attitude maneuvering within a short time and quickly enter the steady state when approaching imaging region,this scheme comprehensively considers the factors of agile mission requirement and satellite constrains,the whole attitude maneuvering process is divided into fast maneuvering section and stable section approaching imaging region,optimal attitude track of fast maneuvering section is obtained by using pseudospectral method,then the attitude track of stable section approaching imaging region is planned in constant attitude angular velocity,and the subsection close-loop controller whose control parameters is obtained by intelligent genetic algorithm is applied to efficiently track the attitude trajectory.Simulation shows that,compared with traditional planning method that only using pseudospectral method,the proposed subsection attitude planning method has better performance in attitude pointing accuracy and attitude angular velocity error. |
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