Cascade observers for output-feedback control under parametric uncertainties, disturbances and arbitrary sensor delays

ABSTRACT

An output-feedback control system for uncertain linear systems with arbitrary delay in the output signal and input disturbances is developed. The state of the system and the disturbances are estimated by observers connected in cascade. Unlike previous works, parametric uncertainties are allowed. Their effects are analysed by using the Small-Gain Theorem. The rejection of the exogenous and matched input disturbances is also considered in the system. The proposed control strategy guarantees global stability of the closed-loop system. A numerical example and an application to underwater vehicle control illustrate the effectiveness of the proposed control strategy to compensate arbitrary delays, disturbances and bounded uncertainties.

Keywords:

• Uncertain systems
• time-delay systems
• output feedback
• cascade observers
• global stabilisation
• matched disturbances

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Ionara Oliveira Marques http://orcid.org/0000-0002-2081-2079

Tiago Roux Oliveira http://orcid.org/0000-0002-2232-8715

José Paulo V. S. Cunha http://orcid.org/0000-0001-6120-9789

Additional information

Funding

This work was supported in part by Brazilian funding agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES – Finance Code 001.