Cascaded sliding-mode observer and its applications in output feedback control part I: Observer design and stability analysis

Abstract

This paper proposes a cascaded sliding-mode observer for systems with high relative degree and studies its applications in output feedback controller design. In part I, the working principle and parameter design of the proposed observer are discussed in detail. It is proved that, within a sufficiently short period of time, the states of the proposed observer will reach the intersection of all the sliding surfaces. On sliding surfaces, the observation error of the proposed observer will converge to sufficiently small values. Compared with traditional high-gain observers, the proposed observer has smaller gain coefficients. In addition, the peaking-phenomenon occurred in the proposed observer is less severe. Furthermore, the proposed observer has a convergence rate of observation error as fast as that of traditional high-gain observers. Simulation studies are carried out on a fifth- order system to verify the properties of the proposed observer.