Intelligent Vibration And Shape Control Of Large Flexible Space Plate-like Structure

The control of large flexible space plate-like structure systems has application to control of spacesystems, aircraft and active optics, to name a few. Large flexible space plate-like structure systems aretypically lightweight and highly flexible. These systems have distributed-parameter dynamics; theirnatural damping is very small; they have many densely packed low-frequency modes; and their modelparameters are uncertain. Moreover, performance requirements such as pointing accuracy, shapecontrol, and bandwidth are very stringent and make the problem of structural vibration more acute.This dissertation is concerned with the intelligent high precision shape and vibration control oflarge flexible space plate-like structures. The dynamics of large flexible space plate-like structuresystems is uncertain due to factors such as high non-linearity, consideration of higher modalfrequencies, high dimensionality, multiple inputs and outputs, operational constraints, as well asunexpected failures of sensors and/or actuators. This dissertation addresses the modeling of thesestructures and the associated vibration and shape control system design technique. Essentially thisthesis consists of four primary sections.Firstly, to ensure the highest energy efficiency, controllability, and observability of the system aprocess of optimization is described. This thesis uses several kinds of intelligent algorithms to solvethree optimization problems for vibration and shape control of the large flexible space plate-likestructure. The first problem optimizes the position of a single group of piezoelectric actuators on thelarge flexible space plate-like structure. The second problem optimizes the activation of apre-determined number of actuators. The third problem optimizes the orientation of a single组ofpiezoelectric actuators on the large flexible space plate-like structure. The fitness function foroptimization is determined form the surface strain measured at a strain sensor for the activation ofeach possible actuator. The advantage of this method lies in the decoupling of the fitness functionformulation from the optimization. In comparison to previous approaches, this allows optimization onmuch more complex geometries where the derivation of an analytical fitness function is prohibitive orimpossible. The optimization results obtained through simulation are verified through a comparisonwith results obtained from a report in the existing literature. The agreement between results fromsimulation and experiment demonstrates the validity of the optimizations.Secondly, a novel modeling method is proposed for flexible space plate-like structure. An explicit,complete, and accurate dynamic mode of large flexible space plate-like structure system is developedusing the proposed new modeling method. The advantage of this type of modeling is that the main mode of vibrations wherein the total energy is concentrated are accommodated thereby avoiding theso-called “spillover” phenomenon. The new model is reduced order model and it is used in designingcontroller for flexible space plate-like structure due to its simplicity, however, it doesn’t lead tocontrol spillover effect which tends to degrade the performance or even destabilize. Besides, the newmodel can facilitate the design of controller. The new modeling method is validated throughcomparative analyses on examples circular plate structure and rectangular plate structure.Thirdly, thesis develops and evaluates several kinds of intelligent strategies for vibration and shapecontrol of large flexible space plate-like structures through computer simulation and experiment.Simulation and experiment results show that intelligent strategies can more effectively vibration andshape control of large flexible space plate-like structures when compared with conventional algorithm.The intelligent vibration and shape control system can be capable of handing complexity, uncertainty,nonlinearity, and variations with time.Finally, the experiment system of intelligent vibration and shape control validate modeling method,muti-objects optimization algorithm and intelligent control strategies.