| 1. |
- Christiansson, Anna-Karin, 1947-, et al.
(författare)
-
Mixed continuous/discrete-time output feedback H∞ control : A unified approach
- 1999
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - 9783952417355 ; , s. 4077-4082
-
Konferensbidrag (refereegranskat)abstract
- A Riccati equation (RE) based solution to the H∞ optimal control problem for mixed continuous/discrete-time systems is presented. The results unify a number of recently penetrated H∞ control problems. In the infinite-horizon case a periodic behaviour is assumed, and it is shown how the related continuous RE with jumps can be replaced by an equivalent discrete periodic RE. A related algebraic RE, which involves the system behaviour during one period, then can be formulated and solved by standard methods. Typical applications are control of continuous-time or discrete-time periodic systems, as well as multirate and sampled-data control, including mixed continuous and sampled-data measurements. © 1999 EUCA.
|
|
| 2. |
- Lindberg, C. -F, et al.
(författare)
-
A pulp and paper simulator for operator training and process optimization
- 2015
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9783952417355 ; , s. 1196-1200
-
Konferensbidrag (refereegranskat)abstract
- A new dynamic simulator for pulp and paper applications has been developed. The simulator is useful for process optimization and operator training, especially when constructing a new paper machine, or rebuilding an existing one, or introducing new employees. The main advantage of the simulator is that the same control system (Distributed Control System source code) and the same displays in the Operator stations are used in the simulator as in the real plant. In this way process operators get very realistic training of various events. Optimization of an existing process line can be done by testing different ways of operation, and then selecting the best way of operation. A suitable rebuild of an existing mill could be found in a similar manner, i.e. by simulating different rebuild possibilities. A DCS functionality checkout can be done before startup of a real mill, since identical DCS code is used in the simulator as in the real mill.
|
|
| 3. |
- Lindgärde, Olof, 1967, et al.
(författare)
-
Frequency analysis for mixed continuous-time and discrete-time periodic systems
- 1999
-
Ingår i: 1999 European Control Conference, ECC 1999; Karlsruhe; Germany; 31 August 1999 through 3 September 1999. - : IEEE. - 9783952417355 ; , s. 4071-4076
-
Konferensbidrag (refereegranskat)abstract
- In this paper mixed continuous-time and discrete-time periodic systems are analyzed in the frequency domain taking the intersample behavior into account. By the presented model structure it is possible to analyze a couple of different control problems in a common framework. The suggested approach is very similar to the one presented by Yamamoto and Khargonekar. The fundamental differences are that the solution is generated, not via the lifted model, but more directly based on the transition matrix of a continuous-time periodic system with jumps. The hybrid model that is analyzed is very clean, but is general compared to model structures considered before. © 1999 EUCA.
|
|
| 4. |
- Lundström, Dag, 1968, et al.
(författare)
-
Transient identification using a fractional derivative model
- 1999
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - : IEEE. - 9783952417355 ; , s. 2865 - 2868
-
Konferensbidrag (refereegranskat)abstract
- Characterizations, control or analyses of dynamic systems often demand low order models in order to be feasible. Dynamic system studies that involve phenomena such as in-elasticity or energy dissipation yields reasonably low order models when fractional derivatives is used. Properties of impulse responses from such models are presented. The results show that both frequency and envelope changes are functions of the derivative order and can thus be used in a function approximation. A suboptimal parameter estimator for such model is presented. © 1999 EUCA.
|
|
| 5. |
- Ninness, Brett, et al.
(författare)
-
Signal spectra and conditioning when using orthonormal parameterisation
- 2015
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9783952417355 ; , s. 4656-4661
-
Konferensbidrag (refereegranskat)abstract
- There has been recent interest in using orthonormalised forms of fixed denominator model structures for system identification. A key motivating factor in the employment of these forms is that of improved numerical properties. Namely, for white input perfect conditioning of the least-squares normal equations is achieved by design. However, for the more usual case of coloured input spectrum, it is not clear what the numerical conditioning properties should be in relation to simpler and perhaps more natural model structures. This paper provides theoretical and empirical evidence to argue that in fact, even though the orthonormal structures are only designed to provide perfect numerical conditioning for white input, they still provide improved conditioning for a wide variety of coloured inputs.
|
|
| 6. |
- Rotander, C., et al.
(författare)
-
Evaluation of AR and ARMA models for estimation of core stability in nuclear reactors
- 2015
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9783952417355 ; , s. 1316-1321
-
Konferensbidrag (refereegranskat)abstract
- High-amplitude power oscillations are undesirable in a nuclear boiling water reactor, since they are a disturbance to reactor operation. The core stability is estimated from passive measurements of the neutron flux, using AR or ARMA models, to verify the stability within the operating domain. Our main concern is to estimate the core stability as accurately as possible. The aim of this paper is to study how this estimation should be carried out. More specifically, pretreatment of data, filtering and decimation, is discussed as means to focus the identificaton to the interesting frequency domain and reduce the mean square error.
|
|
| 7. |
- Wallin, Ragnar, et al.
(författare)
-
Existence of multiple global optima when identifying AR models subject to missing data
- 1999
-
Ingår i: European Control Conference, ECC 1999 - Conference Proceedings. - : IEEE. - 9783952417355 ; , s. 1322-1327
-
Konferensbidrag (refereegranskat)abstract
- If there are significant amounts of data missing, this requires special algorithms for system identification. Such methods have been previoulsy developed and typically result in iterative procedures for the parameter estimation. Since missing data could be viewed as irregular sampling (decimation) of the signals, it is obvious that there is a risk for aliasing. In this case aliasing manifests itself as multiple global optima of the identification loss function. The aim of this paper is to investigate under what circumstances, i.e. for which patterns of missing data and model orders, there may be multiple global optima. Specifically, periodic patterns have been studied, but the results also indicate that for randomly missing data this problem is of lesser concern. It is shown that it is in fact not the fraction of missing data that matters, but rather if there are more than one set of parameters that can fit the obtainable lags of the autocorrelation function.
|
|
