可變結構控制與糢糊控制在飛行控制系統之應用

Abstract

本論文研製之目的為針對一實際的飛行系統,利用可變結構控制法則和模 糊控制法則設計出實用的控制器,使飛機做出平飛,爬升,轉彎及加速等行 為.本論文所重視的是飛行控制系統之分析,可變結構控制器之設計和模糊 控制器之使用.在姿態及高度控制方面使用可變結構控制器,可避免一部份 的不確定性因素(Uncertainty);而速度控制方面使用模糊控制器則是考慮 引擎的模型並不易模擬,使用模糊控制器則可避免"產生精確模型"的問題. 傳統的飛行控制器在飛機作加速飛行時,為考慮因速度改變而造成的參數 變化,必須使用增益調變法,增加設計的複雜度.使用可變結媾控制器的優 點即在於它的"強健性",對於此一因速度改變而造成參數變動的時變系統, 恰有其適用性;同時,它也兼顧了設計上的簡便性.由於引擎的非線性特性 及複雜的結構,可變結構控制器並不適用;模糊控制器在此可視為一非線性 的PI-控制器,對不同速度下的引擎皆有合乎規格的速度輸出. The purpose of the thesis is to design flight controller to make aircraft to fulfill the following maneuvers:level flight, climbing ,level turn and level acceleration. The flight controller is designed with variable structure control law and fuzzy control law for a practical flight control system. For the attitude and altitude hold control system,variable structure controller is used to help the aircraft to reject the matching type uncertainty . For the velocity hold control system, we use fuzzy control law to design the thrust controller,it could avoid the "precise modeling" problem. When the aircraft takes an accelerating flight from subsonic to supersonic,the conventional flight controller must use the gain- scheduling approach to overcome the parameter variations due to the change of the velocity. It always increase the complexity for design. The advantage of variable structure controller is its robustness for such time-varying system and its simplicity in design. Because of the nonlinearity and complexity of the engine system,variable structure controller is not suitable. Here we may treat the fuzzy controller as a nonlinear PI- controller,there exists the suitable velocity performance for engine in every different velocity.