Observer-based robust control for fractional-order nonlinear uncertain systems with input saturation and measurement quantization

Abstract

The paper is concerned with the observer-based robust control problem for fractional-order (FO) nonlinear uncertain systems subject to control input saturation and measurement quantization, in which the fractional commensurate order satisfies α∈(0,1). The state measurements of observer are quantized by a logarithmic quantizer. Firstly, by introducing a continuous frequency distributed equivalent model of fractional integrator, sufficient condition for guaranteeing the asymptotic stability of closed-loop FO systems is established via the indirect Lyapunov approach. Then, by using matrix’s singular value decomposition (SVD) and linear matrix inequality (LMI) technique, the co-design problem of desired observer and controller gains are derived, which will be shown that the solution guarantees the stability of closed-loop FO nonlinear uncertain control systems. Finally, a simulation example is given to illustrate the validity of this method.