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Multivariable Experimental Identification And Adaptive Inverse Control Of Flexible Structures With Close Modes

Posted on:2007-07-03Degree:DoctorType:Dissertation
Country:ChinaCandidate:G ChenFull Text:PDF
GTID:1118360212960397Subject:Navigation, guidance and control
Abstract/Summary:PDF Full Text Request
A distinct character of space flexible structures is small lower frequency damping, which lead to long free vibration of structures when excited by certain disturbance. The operation precision of the equipments will be greatly influenced by the vibration. Another important character of large flexible structures is dense modes. Because the modes are closely spaced, the two or more close modes will be too difficult to identify and be considered as one by classical identification methods, and this will result in fail of the controller design. In addition, flexible structures with close modes can be easily influenced by the environment and changes of structures parameters, which may disable the controller. Thus, there are important realistic meaning and application value for developing the research of the model identification and adaptive control of flexible structures with dense modes.According to this background, in order to increase the damping and suppress the vibration, several major problems in active vibration control of large flexible structures with close modes are discussed in this paper, These problems are: the location of the discrete piezoelectric sensors/actuators on a 2-D flexible plate with close modes; the mathematical description suitable for the controller design of the object, which is infinite dimensional distributed system essentially; optimal control based on the model identified by frequency domain method; adaptive inverse control of the vibration of the flexible structure, etc.The vibration control strategy should be supported by not only the theory and simulations but also practical experiments. In this paper, a 2-D flexible plate test system with close modes is constructed, considering the experimental objects that in most experimental demonstrations there were only 1-D beams or 2-D plates without close modes considered. Based on this flexible plate with close modes, Modeling methods and control design strategy will be studied and realized in the practical experiments, and then it can also be validated whether the detecting and driving system, the software and the hardware, the complement and cost etc are feasible or not.Based on this vibration test system of flexible plate with close modes, it is further researched the optimal allocation of the discrete piezoelectric sensors/actuators. The interaction of the sensors/actuators and the plate is considered and the four lower modes of plate are synthesized. The controllability and observability of different...
Keywords/Search Tags:close modes, flexible structures, active vibration control, piezoelectric sensors/actuators, optimal allocation, multivariable frequency domain identification, maximum likelihood estimator (MLE), least square estimator (LSE), optimal control
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