| 1. |
- Fischer, Britta, et al.
(författare)
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Laguerre shift identification of a pressurized process
- 1998
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Ingår i: Proceedings of the 1998 American Control Conference, ACC, June 24 - 26, 1998, Philadelphia, Pennsylvania, USA. - Piscataway, NJ : IEEE Communications Society. - 0780345304 ; , s. 1933-1937
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Konferensbidrag (refereegranskat)abstract
- The identification of a pressurized tank process is considered. A subspace identification method is employed that identifies the system in question from the Laguerre spectra of the input/output data. The method is presented in a general form and valid in the continuous and in the discrete-time case. Using the input/output Laguerre spectra for identification, instead of the complete input/output data vectors, leads to a considerable data reduction. Furthermore, it is shown by a simulation study that the subspace identification method n4sid works better in Laguerre domain than in the time domain.
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| 2. |
- Johansson, Andreas, et al.
(författare)
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Model-based leakage detection in a pulverized coal injection vessel
- 1998
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Ingår i: Proceedings of the 1998 American Control Conference, ACC, June 24 - 26, 1998, Philadelphia, Pennsylvania, USA. - Piscataway, NJ : IEEE Communications Society. - 0780345304 ; , s. 1742-1746
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Konferensbidrag (refereegranskat)abstract
- A method for detecting and isolating incipient leakages in the valves of a pulverized coal injection vessel for a blast furnace process is presented. Non-linear physical gray-box models of the plant are developed. Values of the unknown parameters are estimated by identification. Observers are constructed for these models and the residuals are used in a Generalized Likelihood Ratio test. The method is successfully tested with real leakages intentionally introduced in the plant.
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| 3. |
- Johansson, Karl H., et al.
(författare)
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A multivariable laboratory process with an adjustable zero
- 1998
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Ingår i: Proceedings of the American Control Conference, Philadelphia, Pennsylvania June 1998. - : AACC. - 0780345304 ; , s. 2045-2049
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Konferensbidrag (refereegranskat)abstract
- A novel multivariable laboratory process that consists of four interconnected water tanks is presented. The linearized dynamics of the system have a multivariable zero that is possible to move along the real axis by changing a valve. The zero can be placed in both the left and the right half-plane. In this way the quadruple-tank process is ideal for illustrating many concepts in multivariable control, particularly performance limitations due to multivariable right half-plane zeros. Accurate models are derived from both physical and experimental data and multi-loop control is illustrated.
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| 4. |
- Johansson, Karl H., et al.
(författare)
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Multivariable controller tuning
- 1998
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Ingår i: Proceedings of the American Control Conference, 1998. - : IEEE. - 0780345304 ; , s. 3514-3518
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Konferensbidrag (refereegranskat)abstract
- The problem of tuning individual loops in a multivariable controller is investigated. It is shown how the performance of a specific loop relates to a row in the controller matrix. Several interpretations of this relation are given. An algorithm is also presented that estimates the model required for the tuning via a relay feedback experiment. The algorithm does not need any prior information about the system or the controller. The results are illustrated by an example.
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| 5. |
- Larsson, John Erik, et al.
(författare)
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Paper machine dry line position control during grade changes
- 1998
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Ingår i: Proceedings of the 1998 American Control Conference. - Piscataway, NJ : IEEE Communications Society. - 0780345304 ; , s. 2997-3001
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Konferensbidrag (refereegranskat)abstract
- The detection and control of the dry line machine direction position on a fourdrinier paper machine are considered. The dry line position is detected using a digital image processing system consisting of a CCD camera, a frame grabber and a standard PC. The system was installed on a kraft liner machine and both open loop and closed loop experiments were performed with encouraging results. The introduction of automatic control of the dry line position reduces the time for grade changes and it also reduces the machine operators work load. The reduced time leads to smaller production losses and hence to economical benefits.
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| 6. |
- Nilsson, Johan, et al.
(författare)
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Some Topics in Real-time Control
- 1998
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Ingår i: IEEE Xplore : Proceedings of the 1998 American Control Conference. ACC - Proceedings of the 1998 American Control Conference. ACC. - 0780345304
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Konferensbidrag (refereegranskat)abstract
- This paper discusses some problems that can arise in distributed real-time control systems, for instance, sampling- interval jitter, timeout, and asynchronous loops.
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| 7. |
- Pedersen, Lars Malcolm, et al.
(författare)
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On the reheat furnace control problem
- 1998
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Ingår i: IEEE Xplore : Proceedings of the 1998 American Control Conference. ACC - Proceedings of the 1998 American Control Conference. ACC. - 0780345304
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Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to develop a model and control algorithm for the slab temperature control problem, which is the control of a number of steel blocks (slabs) passing through a furnace burner zone. The slab temperature is controlled by varying the zone temperatrure. First a model for a single slab passing through the furnace is developed and the parameters are estimated. Data from the reheat furnace no. 2 at The Danish Steel Work Ltd. is used for the identification. Based on the slingle slab model a model for all slabs in a burner zone is constructed. The controllability of this model is analyzed and it is concluded that problems can arise if the temperature of two or more slabs are equal. A quadratic error function for the slab temperature is defined. From this error function and the constructed model a nonlinear controller is designed to minimize the vlaue of the error function. The stability of the control law is analyzed and it is concluded that the controlled system is stable.
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| 8. |
- Zell, Caj, et al.
(författare)
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Robust detection and isolation of mechanical faults in processes driven by induction machines
- 1998
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Ingår i: Proceedings of the 1998 American Control Conference, ACC, June 24 - 26, 1998, Philadelphia, Pennsylvania, USA. - Piscataway, NJ : IEEE Communications Society. - 0780345304 ; , s. 3307-3311
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Konferensbidrag (refereegranskat)abstract
- A robust model-based technique for fault detection and isolation in electro-mechanical systems comprising induction machines is introduced. A state observer for reconstructing the magnetic flux components of the induction machine and thereby the electrical torque is used in combination with a robust state estimator for the mechanical load torque based on a model with structured uncertainties. The fault detection and isolation problem is reduced to validation/invalidation of the models representing different fault hypotheses. The practical applicability of the method is demonstrated in a simulation example
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