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Sliding Mode Control On Flexibile Spacecraft

Posted on:2008-08-20Degree:MasterType:Thesis
Country:ChinaCandidate:G J ZhangFull Text:PDF
GTID:2132360245498118Subject:Control theory and control engineering
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This paper deals with a kind of spacecraft consisting of a rapid platform and two identical flexible appendages, with attitude control of the flexible spacecraft being investigated. The aim of this paper is to suppress the flexible vibration during attitude maneuvering. Active vibration control technique is the key technology of designing of attitude control system for large flexible spacecraft to fulfill mission requirements. The maim contents of this dissertation are as the follows:First, the developing process and current situation of the attitude control of the flexible spacecraft are introduced and the development history and research status of VSC are summarized,. In chapter 2 of this dissertation, the CSVS method is summarized to several theorems. The large angle maneuver tasks applying CSVS method are simulated. By using various CSVS methods, desired maneuver tasks can be realized while suppressing flexible vibration effectively.In chapter 3, corresponding researches are done to improve control precision of system by combing closed-loop controller and CSVS method, which can effectively suppress vibration caused by both controller and structure flexibility. Based on the piezoelectric material elements as sensors/actuators bonded on the surface of the beam appendages, we add the positive position feedback (PPF) control technique, Simulation results demonstrate the proposed approach can significantly reduce the vibration of the flexible appendages during and after the maneuver operations.According to the immeasurable modes of flexible spacecraft and the uncertainties, a robust control method is presented in this thesis based on variable structure output feedback control (VSOFC). CSVS method is used to modify the input such that the flexible modes are not excited. For further suppressing the flexible vibration, uses the piezoelectric as sensors/actuators to actively suppress certain flexible modes by adding PPF compensators. An attractive feature of the method is that the vibration reduction and attitude control are achieved separately in the two separate feedback loops, allowing the pointing requirements and simultaneous vibrations suppression to be satisfied independently of one another. Compared with conventional methods, the proposed scheme guarantees closed-loop system stability, and yields good performance and robustness in the presence of parametric uncertainties and external disturbance as well. Simulation results for the spacecraft model illustrate the precise pointing control and vibration suppression.
Keywords/Search Tags:flexible spacecraft, component synthesis active vibration suppression(CSVS), positive position feedback(PPF), sliding mode control
PDF Full Text Request
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