| 1. |
- Berndtsson, Magnus, et al.
(författare)
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Design of a dynamic threshold generator for λ-tuned control loops
- 2008
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 16:5, s. 623-631
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Tidskriftsartikel (refereegranskat)abstract
- A dynamic threshold generator is employed for detecting faults in λ-tuned control loops. To this end, an optimizationalgorithm for dynamic threshold generators is proposed. The a priori-information from λ-tuning is used in designing astate estimator with integral action. A dynamic threshold generator for the residual of this state estimator is derived and the optimization algorithm is applied. Simulations with measurement data from an experimental water tank setup show that the method is capable of detecting a small fault without generating false alarms.
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| 2. |
- Düstegör, Dilek, et al.
(författare)
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Structural Analysis of Fault Isolability in the DAMADICS benchmark
- 2006
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 14:6, s. 597-608
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Tidskriftsartikel (refereegranskat)abstract
- Structural analysis is a powerful tool for early determination of fault detectability/fault isolability possibilities. It is shown how different levels of knowledge about faults can be incorporated in a structural fault isolability analysis and how they result in different isolability properties. The results are evaluated on the DAMADICS valve benchmark model. It is also shown how to determine which faults in the benchmark that need further modelling to get desired isolability properties of the diagnosis system.
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| 3. |
- Eidehall, Andreas, et al.
(författare)
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Joint Road Geometry Estimation and Vehicle Tracking
- 2007
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Ingår i: Control Engineering Practice. - Linköping : Elsevier. - 0967-0661 .- 1873-6939. ; 15:12, s. 1484-1494
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Tidskriftsartikel (refereegranskat)abstract
- Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles. Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.
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| 4. |
- Ekvall, Jenny, et al.
(författare)
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Improved web break strategy using a new approach for steam pressure control in paper machines
- 2008
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 16:10, s. 1151-1160
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new strategy for steam pressure control during web breaks in the paper machine. The aim was to restart paper production with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions which were used to find the optimal steam pressure trajectory during web breaks. The resulting strategy has been tested on a paper machine with good results and it has been well received at the mill. (C) 2008 Elsevier Ltd. All rights reserved.
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| 5. |
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| 6. |
- Falkman, Petter, 1972, et al.
(författare)
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Specification of a batch plant using process algebra and petri nets
- 2009
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Ingår i: Control Engineering Practice. - : Pergamon. - 0967-0661 .- 1873-6939. ; 17:9, s. 1004-1015
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Tidskriftsartikel (refereegranskat)abstract
- The focus of the present paper is on the specification of routing and resource allocation systems. Such systems can be described as a set of shared resources and a set of products. The products utilize the resources in order to be manipulated according to a certain specification. This product specification consists of a set of operations that are to be executed in a certain order by specific resources. This results in a desired product route through the resource system, and hence the product specification is also called a routing specification. The process algebra petri net (PPN) formalism, i.e. a combination of petri nets and process algebra, implies efficient and less complex models for routing specifications compared to PNs and automata descriptions. The aim of this paper is to show how the PPN language can be used in order to simplify the specification of desired routes of the chemical batch process.
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| 7. |
- Hellström, Erik, et al.
(författare)
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Look-ahead control for heavy trucks to minimize trip time and fuel consumption
- 2009
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 17:2, s. 245-254
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Tidskriftsartikel (refereegranskat)abstract
- The scenario studied is a drive mission for a heavy diesel truck. With aid of an on board road slope database in combination with a GPS unit, information about the road geometry ahead is extracted. This look-ahead information is used in an optimization of the velocity trajectory with respect to a criterion formulation that weighs trip time and fuel consumption. A dynamic programming algorithm is devised and used in a predictive control scheme by constantly feeding the conventional cruise controller with new set points. The algorithm is evaluated with a real truck on a highway, and the experimental results show that the fuel consumption is significantly reduced.
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| 8. |
- Höckerdal, Erik, et al.
(författare)
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Observer design and model augmentation for bias compensation with a truck engine application
- 2009
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 17:3, s. 408-417
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Tidskriftsartikel (refereegranskat)abstract
- A systematic design method for reducing bias in observers is developed. The method utilizes an observable default model of the system together with measurement data from the real system and estimates a model augmentation. The augmented model is then used to design an observer which reduces the estimation bias compared to an observer based on the default model. Three main results are a characterization of possible augmentations from observability perspectives, a parameterization of the augmentations from the method, and a robustness analysis of the proposed augmentation estimation method. The method is applied to a truck engine where the resulting augmented observer reduces the estimation bias by 50% in a European transient cycle.
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| 9. |
- Iannelli, Luigi, et al.
(författare)
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Subtleties in the averaging of a class of hybrid systems with applications to power converters
- 2008
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 16:8, s. 961-975
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Tidskriftsartikel (refereegranskat)abstract
- High-frequency dither signals are commonly used to implement modulation schemes in power electronics converters. These systems represent an interesting class of hybrid systems with external excitation. They have a rich dynamical behavior, which cannot be easily understood intuitively. Despite the common use of averaging techniques in power electronics, it was only recently proved that a dithered hybrid system can be approximated by an averaged system under certain conditions on the dither signal. Averaging and averaged models for various types of power converters are analyzed in the paper. It is shown that the averaged nonlinearity depends on the dither shape and that dither signals with Lipschitz-continuous averaged nonlinearities can be used to adapt the equivalent gain of power converters. Practical stability of the original dithered system can be inferred by analyzing a simpler averaged system. The main contribution of the paper is to show that the averaged and the dithered systems may have drastically different behavior if the assumptions of the recently developed averaging theory for dithered hybrid systems are violated. Several practical experiments and simulation examples of power electronics converters are discussed. They indicate that the conditions on the dither signal imposed by the averaging theory are rather tight.
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| 10. |
- Klein, Marcus, et al.
(författare)
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Compression ratio estimation based on cylinder pressure data
- 2006
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Ingår i: Control Engineering Practice. - : Elsevier BV. - 0967-0661 .- 1873-6939. ; 14:3 SPEC. ISS., s. 197-211
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Tidskriftsartikel (refereegranskat)abstract
- Four methods for compression ratio estimation based on cylinder pressure traces are developed and evaluated for both simulated and experimental cycles. The first three methods rely upon a model of polytropic compression for the cylinder pressure. It is shown that they give a good estimate of the compression ratio at low compression ratios, although the estimates are biased. A method based on a variable projection algorithm with a logarithmic norm of the cylinder pressure yields the smallest confidence intervals and shortest computational time for these three methods. This method is recommended when computational time is an important issue. The polytropic pressure model lacks information about heat transfer and therefore the estimation bias increases with the compression ratio. The fourth method includes heat transfer, crevice effects, and a commonly used heat release model for firing cycles. This method is able to estimate the compression ratio more accurately in terms of bias and variance. The method is more computationally demanding and is therefore recommended when estimation accuracy is the most important property. © 2005 Elsevier Ltd. All rights reserved.
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