| Summary: | 博士 === 國立成功大學 === 航空太空工程學系碩博士班 === 96 === This dissertation proposes a new approach to consider the nonlinear H_inf control of hovering aircraft that is described by six-degree-of-freedom nonlinear dynamics with plant uncertainties, which are due to the variation of moments of inertia, and are caused by fuel consumption and/or payload operation. Taking account of nonlinear effect, plant uncertainty, and exogenous disturbances which is caused by wind gust, we show in this dissertation that the six-degree-of-freedom nonlinear H_inf controller can be exactly decoupled into two three-degree-of-freedom controllers. One controller is for translational motion; while the other is for rotational motion. It could be done even when the longitudinal and lateral dynamics of the flight vehicle in hovering is highly nonlinear and severely coupled. In this dissertation, a numerical simulation has proved the decoupling properties of the nonlinear H_inf control system. Simultaneously show that nonlinear H_inf controller can provide good performance and good stability for hovering flight. We also evaluate the flying quality through the simulation. The helicopter flying quality by quickness index is adopted to test the robustness of the H_inf controller. It shows that the controller can maintain the specifications in level-1 standard while Beaufort scale of wind gust changes. Due to the nonlinear H_inf decoupling controls for hovering flight, the system can provide more robustness and have better disturbance rejection abilities.
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