Title: Bond-graph-based controller design for the quadruple-tank process

Authors: Matías A. Nacusse; Sergio J. Junco

Addresses: LAC, Laboratorio de Automatización y Control, Departamento de Control, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de Rosario, Ríobamba 245 Bis – S2000EKE Rosario, Argentina ' LAC, Laboratorio de Automatización y Control, Departamento de Control, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de Rosario, Ríobamba 245 Bis – S2000EKE Rosario, Argentina

Abstract: The quadruple-tank process has been proposed as a benchmark for multivariable control system design. This paper addresses the design in the bond-graph domain of a robust controller having the volumetric flows of two pumps as manipulated variables and the level of the two lower tanks as the regulated outputs. The basic control objectives are expressed in terms of desired closed-loop energy and power-dissipation functions and captured in the bond-graph domain by means of a so-called target bond-graph. A basic controller design performed via bond-graph prototyping yields a primary control law which is further robustified against parameter uncertainties, measurement deviations and faults using the diagnostic bond-graph concept. This results in an additional closed-loop consisting of a PI-law which is represented by a physically meaningful bond-graph subsystem. The design methodology is first developed on a simpler two-tank SISO-control problem and then straightforwardly extended to the multivariable problem with the help of some causal manipulations on the four-tank bond-graph model.

Keywords: quadruple tank systems; bond graphs; prototyping; nonlinear control; energy-based control; robust control; fault-tolerant control; fault tolerance; controller design; volumetric flows; pumps; pump flow; power dissipation; modelling; multivariable control.

DOI: 10.1504/IJSPM.2015.070474

International Journal of Simulation and Process Modelling, 2015 Vol.10 No.2, pp.179 - 191

Received: 14 Mar 2014
Accepted: 25 Aug 2014

Published online: 07 Jul 2015 *

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