Fixed-time sliding mode based observer for nonlinear systems with unknown parameters and unknown inputs

• Published in: IET control theory & applications Vol. 14; no. 14; pp. 1920 - 1927
• Main Authors: Langueh, Kokou A.A., Zheng, Gang, Floquet, Thierry
• Format: Journal Article
• Language: English
• Published: Institution of Engineering and Technology 2020
• Subjects: Automatic Control Engineering; Computer Science
• ISSN: 1751-8644
• DOI: 10.1049/iet-cta.2019.1049

It is of importance to design observers for multi-variable nonlinear systems with unknown parameters and partially driven by unknown inputs. Such a problem arises in systems subject to disturbances or with inaccessible inputs and in many applications such as parameter identification, fault detection and isolation or cryptography. In this paper, the problem of fixed-time observation for nonlinear dynamical systems with unknown parameter and inputs is studied. Conditions on full/partial state and parameters identification are provided by the the way of an observation algorithm based on differential geometry theory. Then, an uniform differentiator for estimating simultaneously the states and unknown parameters in fixed-time while avoiding observability singularities is designed. An example on topology identification of network systems is described to show the effectiveness of the proposed method.