This paper addresses two important aspects of anti-windup (AW) designs, namely the parametrization of linear AW compensators, and the role of artificial nonlinearity (AN) in the design of AW compensators for multivari...
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ISBN:
(纸本)9783952426906
This paper addresses two important aspects of anti-windup (AW) designs, namely the parametrization of linear AW compensators, and the role of artificial nonlinearity (AN) in the design of AW compensators for multivariable systems. For the first issue, a simple parametrization is given using the classical feedback structure in the framework of constrained unity feedback multivariable control system. Conditions for controller implementability and closed-loop stability are stated in terms of this parametrization. For the second issue, two existing AN designs for coordinate plant inputs whenever one plant input enters saturation are reviewed. The first design is the widely used input direction preserving technique, and the second is an optimal AN design. A comparative simulation study illustrates that the conditioning technique, enhanced by optimal AN design, gives the best tracking performance among different existing methods.
In this paper we consider the fault isolation problem for the linear time varying systems. Our approach is based on characterization of the observability of LTV systems by Kalman's rank condition, which permits us...
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ISBN:
(纸本)9783952426906
In this paper we consider the fault isolation problem for the linear time varying systems. Our approach is based on characterization of the observability of LTV systems by Kalman's rank condition, which permits us to design fault detection filters, feeding also the derivatives of the inputs and the outputs. We prove, using a computable method, that the isolation problem can be solved by generalized Luenberger's observer if and only if the detectability and the weak separability of fault signatures holds.
At ACE'94 the concept of a process laboratory for analysis, education and research of control engineering approaches and methods was presented. Three years later we are in the middle of the work on the realisation...
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At ACE'94 the concept of a process laboratory for analysis, education and research of control engineering approaches and methods was presented. Three years later we are in the middle of the work on the realisation of this laboratory, which serves a number of purposes: development and application, research, training and education in the area of industrial process control. The paper describes in detail the configuration of the process laboratory, the upgraded control system and the software tools used during our research and educational programs.
The design of a diagnostic system based on mathematical models of the plant components is performed for a gas-liquid separation unit. This design includes first modelling of the process by using physical laws governin...
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The design of a diagnostic system based on mathematical models of the plant components is performed for a gas-liquid separation unit. This design includes first modelling of the process by using physical laws governing its behaviour. Hardware redundancy and simple nonlinear observers are used to synthesise a residual generator with 7 outputs. The generalized likelihood ratio (GLR) test allows one to evaluate the residuals. Tuning of the design parameters is discussed, and a reinitialization procedure is proposed in order to distinguish between temporary and permanent changes in the mean of the residuals. Simulations are used to illustrate the choice of the design parameters
A grey box model-based method for fault diagnosis is proposed in this paper which is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the fault: the deterioration of t...
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A grey box model-based method for fault diagnosis is proposed in this paper which is based on a first principle model of the process unit: a heat exchanger, and on a grey box model of the fault: the deterioration of the heat transfer surface by aging. Under normal operating conditions the heat transfer coefficient is constant or slowly decreasing due to a layer of settled material building up on the heat transfer surface, and we propose to use a recursive least squares estimator with forgetting factor to track the heat transfer coefficients during these stages. In old heat exchangers, big chunks of the settled material can break away from the surface causing the heat transfer coefficients to rise sharply. This fault is detected via detection of abrupt positive jump in the estimated heat transfer coefficients using a Hinkley detector
A component-centred approach to the derivation of the diagnostic rules for continuous processes is presented below. It strongly relies on the causal representation of fault propagation within the basic process units w...
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A component-centred approach to the derivation of the diagnostic rules for continuous processes is presented below. It strongly relies on the causal representation of fault propagation within the basic process units where the modelling convention of Hunt et al. (1993) is adopted. Basic information concerning the disturbance and fault propagation is stored in terms of the unit mini-fault tree. Additional information on special process structures is treated systematically by making use of template trees. The diagnostic rules for the entire process are obtained by chaining the mini-trees and combining the deviations caused by a fault. The paper presents some improvements concerning more efficient on-line use of the resulting rules. A major contribution concerns the realisation of the CAD environment for the prototyping of the diagnostic systems based on the process flowsheet and library of process components. Such a concept enables the re-usability of the basic process component models and the incremental development of the components library.
The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input...
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The passivity property of dissipative mechanical structures has long been exploited in designing passive controllers that provide robust stability even in the presence of unmodeled dynamics of the system. For an input/output map of a flexible structure to be passive, collocation of the actuators and sensors is required and also the sensors should measure the velocity of the system. The so-called smart structures frequently have more sensors than actuators. Therefore, the passive controller can at best utilize only a subset of the sensors. In this paper we consider the design of a squaring down matrix which would render a system passive subject to some additional performance considerations. The problem of obtaining the synthesized passive output is cast as a set of linear matrix inequalities (LMIs) which can be efficiently solved by the LMI Toolbox in Matlab. We apply this procedure with the assumption that the sensors provide both displacement and velocity information which is generally not true. We show that the passive controllers can be implemented without the use of velocity information. By using synthesized passive outputs in addition to naturally occurring passive outputs, we obtain better system performance. We present experimental results involving a single flexible beam with torque input and hub angular position and strain gage outputs.
A procedure for the postoptimal analysis of dynamic positioning control system of floating vessels is proposed. The control system design is based on the optimal constrained covariance control (OC 3 ). Using the OC 3 ...
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A procedure for the postoptimal analysis of dynamic positioning control system of floating vessels is proposed. The control system design is based on the optimal constrained covariance control (OC 3 ). Using the OC 3 technique, the disadvantages of the classical LQG optimal control technique are avoided. The presented numerical example illustrates the properties of the new approach.
This paper presents a new approach for approximate identification under the H 2 criterion where the model is parametrized in a basis generated by apriori knowledge on the location of system poles. A frequency domain i...
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This paper presents a new approach for approximate identification under the H 2 criterion where the model is parametrized in a basis generated by apriori knowledge on the location of system poles. A frequency domain identification procedure is proposed and it is applied to obtain models for the MIT interferometer testbed.
A new matrix rule-based model of discrete-part discrete event systems is given that, together with the well-known Petri net marking transition equation, yields a complete matrix-based dynamical description of these sy...
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A new matrix rule-based model of discrete-part discrete event systems is given that, together with the well-known Petri net marking transition equation, yields a complete matrix-based dynamical description of these systems. In this application to deadlock analysis, the exact relations between circular blockings and deadlocks are given for a large class of reentrant flow lines. Explicit matrix equations are given for online dynamic deadlock analysis in terms of circular blockings, and certain 'critical siphons' and 'critical subsystems'. This allows efficient dispatching with deadlock avoidance using a generalized kanban scheme. For the class of flow lines considered, the existence of matrix formulae shows that deadlock analysis is not NP-complete, but of polynomial complexity.
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