This paper considers global output feedback stabilization via sampled-data control for a general class of nonlinear systems, which admit unknown control coefficients and nonderivable output function. A sector region of the output function is given by utilizing a technical lemma, and a sampled-data controller is designed by combining a robust state stabilizer and a reduced-order sampled-data observer. By carefully choosing an appropriate sampling period, the proposed controller guarantees the globally asymptotical stability of the closed-loop systems.
KEYWORDSnonlinear systems, output feedback, sampled-data control, unknown output function where (t) = ( 1 (t), … , n (t)) ⊤ ∈ R n is the unmeasurable state, u(t) ∈ R is the control input, and y(t) ∈ R is the output. 1 (t), … , n (t) are unknown control coefficients, and h(·) is an unknown output function. For i = 1, … , n, nonlinearities f i (·) are assumed to be continuous in t and locally Lipschitz in and u, and f i (t, 0, 0) = 0. Output function h(·) is Lipschitz in its argument and vanishes at zero.With the rapid development of computer technology, more and more controllers are being implemented by digital computers. The design and analysis of sampled-data control for nonlinear systems have received a great deal of attention (see, for example, other works 1-4 ). However, it is not a trivial problem to design sampled-data controllers for nonlinear systems because unlike the linear case, the equivalence between sampled linear continuous-time systems and discrete-time systems is no longer available. In the literatures, a discretization method based on the discrete-time approximation of Int J Robust Nonlinear Control. 2018;28:2853-2867.wileyonlinelibrary.com/journal/rnc