This paper investigates the adaptive quasi-passification-based stabilization problem for a class of switched nonlinearly parameterized systems via average dwell time method. First, when all the subsystems have any same relative degree, the global practical stability is achieved by combining the recursive feedback quasipassification design technique with a switched adaptive control technique. The states and parameter estimation errors converge to the ball whose sizes can be reduced by choosing appropriate design parameters. Second, when the system states are unavailable for measurements, adaptive output feedback controllers are designed to stabilize the system using quasi-passivity. The proposed output feedback controllers do not depend on any state observer. Finally, three examples show the effectiveness of the proposed methods.
KEYWORDSadaptive quasi-passification, recursive feedback quasi-passification, global practical stability, switched nonlinear systems, average dwell timeAs a special kind of hybrid dynamical systems, a switched system is composed of a family of continuous-time subsystems and a rule that governs the switching among them. Switched systems have attracted a great amount of attention because of their importance from both theoretical and practical points of view. 1-4 Many practical systems, such as aircraft control systems, mechanical systems and electrical systems, can be modeled as switched systems. 2,4-6 Stability analysis and stabilization problems for switched systems have been extensively studied. Since uncertainties which may cause instability and undesirable performance exist widely in real world systems, one should consider these effects on plant. H ∞ control, robust control and adaptive control are often used to deal with uncertainties. 7-13 For parametric uncertainties, adaptive control has been one of the most effective methods. The asymptotic stability is often the desired performance. 3,5,10,11,14 However, in many practical applications, asymptotic stability may be difficult to obtain due to large uncertainties. From an engineering point of view, the global practical stability can be often satisfactory. 12,13 On the other hand, passivity, introduced by Willems, 15 provides an effective tool for solving the problems of stability analysis and stabilization. 15-17 When a system involves unknown parameters, the adaptive passification and adaptive passivity-based stabilization problems were solved in. 6,18-21 However, the exact feedback passification and asymptotical stabilization problems were intractable because of the large system uncertainties. Therefore, the development of passivity-based methodology for this case would be desirable. The convention passivity property was extended to quasipassivity, 22,23 which were used to investigate the ultimate boundedness of state trajectories of nonlinear uncertain systems. Similar to the concept of strict quasi-passivity, the concepts of passivity with respect to a set and semipassivity were proposed to derive a stability property of the set....