Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments

This paper addresses the observability analysis and observer design for a nonlinear interacting three-tank system. The plant configuration is first described using the process and instrumentation diagram (P&ID) and a state–space realization is derived; some insights about the behavior of the non...

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Main Authors: Santiago Rúa, Rafael E. Vásquez, Naveen Crasta, Carlos A. Zuluaga
Format: Article
Language:English
Published: MDPI AG 2020-11-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/20/23/6738
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author Santiago Rúa
Rafael E. Vásquez
Naveen Crasta
Carlos A. Zuluaga
author_facet Santiago Rúa
Rafael E. Vásquez
Naveen Crasta
Carlos A. Zuluaga
author_sort Santiago Rúa
collection DOAJ
description This paper addresses the observability analysis and observer design for a nonlinear interacting three-tank system. The plant configuration is first described using the process and instrumentation diagram (P&ID) and a state–space realization is derived; some insights about the behavior of the nonlinear system, considering equilibrium points and the phase portrait are provided. Then, observability in the Hermann–Krener sense is analyzed. A high-gain observer (HGO) is then designed, using the equivalence of the original state–space realization with its observability canonical form, in order to guarantee convergence of the state estimation. The performance was validated through simulation and experiments in a multipurpose plant equipped with real sensors; the HGO response was compared to a Luenberger observer (for a linear approximation of the plant) and the Extended Kalman Filter (for which convergence is not guaranteed), considering nonlinearities, interaction, disturbances and noise. Theoretical and experimental results show that the HGO can provide robust estimation and disturbance rejection, despite the sensitivity of HGOs to noisy variables in processes such as level of liquids.
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spelling doaj.art-3859e9f15a5e43fd873d2c8a1330d2622023-11-20T22:16:45ZengMDPI AGSensors1424-82202020-11-012023673810.3390/s20236738Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and ExperimentsSantiago Rúa0Rafael E. Vásquez1Naveen Crasta2Carlos A. Zuluaga3School of Engineering, Universidad Pontificia Bolivariana, Medellín 050031, ColombiaSchool of Engineering, Universidad Pontificia Bolivariana, Medellín 050031, ColombiaInstitute for Systems and Robotics, Instituto Superior Técnico, 1049-001 Lisbon, PortugalSchool of Engineering, Universidad Pontificia Bolivariana, Medellín 050031, ColombiaThis paper addresses the observability analysis and observer design for a nonlinear interacting three-tank system. The plant configuration is first described using the process and instrumentation diagram (P&ID) and a state–space realization is derived; some insights about the behavior of the nonlinear system, considering equilibrium points and the phase portrait are provided. Then, observability in the Hermann–Krener sense is analyzed. A high-gain observer (HGO) is then designed, using the equivalence of the original state–space realization with its observability canonical form, in order to guarantee convergence of the state estimation. The performance was validated through simulation and experiments in a multipurpose plant equipped with real sensors; the HGO response was compared to a Luenberger observer (for a linear approximation of the plant) and the Extended Kalman Filter (for which convergence is not guaranteed), considering nonlinearities, interaction, disturbances and noise. Theoretical and experimental results show that the HGO can provide robust estimation and disturbance rejection, despite the sensitivity of HGOs to noisy variables in processes such as level of liquids.https://www.mdpi.com/1424-8220/20/23/6738observability analysishigh-gain observerstate estimationadvanced process controlsoft sensorthree-tank system
spellingShingle Santiago Rúa
Rafael E. Vásquez
Naveen Crasta
Carlos A. Zuluaga
Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
Sensors
observability analysis
high-gain observer
state estimation
advanced process control
soft sensor
three-tank system
title Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
title_full Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
title_fullStr Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
title_full_unstemmed Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
title_short Observability Analysis and Observer Design for a Nonlinear Three-Tank System: Theory and Experiments
title_sort observability analysis and observer design for a nonlinear three tank system theory and experiments
topic observability analysis
high-gain observer
state estimation
advanced process control
soft sensor
three-tank system
url https://www.mdpi.com/1424-8220/20/23/6738
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