Relaxations of Conditions of Lyapunov Functions

Öz

In this study, stability conditions are given for nonlinear time varying systems using the classical Lyapunov 2nd Method and its arguments. A novel approach is utilized and so that uniform stability can also be proved by using an unclassical Lyapunov Function. In contrast with the studies in the literature, Lyapunov Function is allowed to be negative definite and increasing through the system. To construct a classical Lyapunov Function, we use a reverse time approach methodology for the intervals where the unclassical one is increasing. So we prove the stability using a new Lyapunov Function construction methodology. The main result shows that the existence of such a function guarantees the stability of the origin. Some numerical examples are also given to demonstrate the efficiency of the method we use.

Anahtar Kelimeler

• Nonlinear Systems
• Stability Analysis
• Lyapunov 2nd Method
• Lyapunov Function
• Time-varying Systems
• Uniform Stability

Lyapunov Fonksiyonun Koşullarının Gevşetilmesi

Öz

Bu çalışmada, klasik Lyapunov 2. Metodu ve bu metoda dair argümanlar kullanılarak, zamanla değişen yapıdaki Doğrusal Olmayan Sistemler için kararlı olma koşulları verilmektedir. Özgün bir yaklaşım kullanılmış ve böylece düzgün kararlılık, klasik olmayan bir Lyapunov Fonksiyonu kullanılarak da ayrıca ispatlanabilmiştir. Literatürdeki çalışmaların aksine, kullandığımız klasik olmayan Lyapunov Fonksiyonunun bazı aralıklar için sistem boyunca artan ve negatif tanımlı olmasına izin verilmiştir. Klasik Lyapunov Fonksiyonu’nu inşaa etmek için, klasik olmayan Lyapunov Fonksiyonu’nun artan olduğu aralıklarda ters zaman yaklaşımını kullanıyoruz. Böylece yeni bir Lyapunov Fonksiyonu inşa etme yaklaşımı kullanarak kararlığı ispatlamış oluyoruz. Ana sonuç böyle bir fonksiyonun varlığının, orjinin kararlılığını garantilediğini gösterir. Yaklaşımın efektif olduğunu göstermek için ayrıca bir takım nümerik örnekler de verilmiştir.

Anahtar Kelimeler

• Nonlineer Sistemler
• Kararlılık Analizi
• Lyapunov 2. Metodu
• Lyapunov Fonksiyonu
• Zamanla değişen Sistemler
• Düzgün Kararlılık

Kaynakça

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