| 1. |
- Forsman, Krister, et al.
(författare)
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FuzzyCAT - Towards a Mathematical Analysis of Fuzzy Controllers
- 1993
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Ingår i: Proceedings of the 32nd Conference on Decision and Control. - Linköping : Linköping University Electronic Press. - 0780312988 ; , s. 1284-1285 vol.2
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to show that, contrary to what is commonly believed, it is possible to get rather simple analytic expressions for a class of fuzzy controllers. The authors describe a Maple package called FuzzyCAT that supports analysis and simulation of fuzzy controllers. The restrictions made in the program concern the shape of the membership functions, the defuzzification methods available and the number of input and output variables.
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| 2. |
- Forsman, Krister, et al.
(författare)
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Solving the ARE Symbolically
- 1993
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Ingår i: Proceedings of the 32nd Conference on Decision and Control. - Linköping : Linköping University. - 0780312988 ; , s. 363-368 vol.1
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Konferensbidrag (refereegranskat)abstract
- Methods from computer algebra, mostly so called Grobner bases (gb) from commutative algebra, are used to solve the algebraic Riccati equation (ARE) symbolically. The methods suggested allow us to track the influence of parameters in the system or penalty matrices on the solution. Some nontrivial aspects arise when addressing the problem from the point of view commutative algebra, for example the original equations are rational, not polynomial. We explain how this can be dealt with rather easily. Some methods for lowering the computational complexity are suggested and different methods are compared regarding efficiency. Preprocessing of the equations before applying gb can make computations more efficient.
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| 3. |
- Hjalmarsson, Håkan, 1962-
(författare)
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Asymptotic correct correlation tests in model validation
- 1993
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - San Antonio, TX, USA. - 0780312988 ; , s. 2058-2059
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Konferensbidrag (refereegranskat)abstract
- It is well-known that correlation tests may give true significance levels that differ significantly from the desired ones; the tests are less inclined to reject the null hypothesis when second-hand data are used compared with how they are designed to behave and the situation is the opposite for 'fresh' data. The reason is that the tests are based on the assumption that the limit model (corresponding to infinite data) is available. In this contribution we propose a methodology to design correlation tests that avoid this artifact. This leads to tests of higher order correlations.
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| 4. |
- Hjalmarsson, Håkan, 1962-, et al.
(författare)
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Discussion of `unknown-but-bounded' disturbances in system identification
- 1993
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - San Antonio, TX, USA : Linköping University. - 0780312988 ; , s. 535-536
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Konferensbidrag (refereegranskat)abstract
- In this contribution we point out that a fundamental property of a disturbance is that it is independent of the input - otherwise it is rather part of the system. Based on this characterization we show that parameter convergence can be obtained not only for stochastic but also for unknown-but-bounded disturbances if the input is at our disposal.
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| 5. |
- Klein, Inger, et al.
(författare)
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Automatic Creation of Sequential Control Schemes in Polynomial Time
- 1993
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Ingår i: Proceedings of the 32nd Conference on Decision and Control. - Linköping : Linköping University. - 0780312988 ; , s. 211-216 vol.1
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Konferensbidrag (refereegranskat)abstract
- Of all hard- and software developed for industrial control purposes, the majority is devoted to sequential, or binary valued, control and only a minor part to classical linear control. The sequential parts of the controller are typically invoked during startup or shut-down phases to bring the system either into its normal operating region or into some safe standby region. Despite its importance, fairly little theoretical research has been devoted to this area, and sequential control programs are still created manually without much support for a systematic approach. We propose a method to create sequential control programs automatically and online upon request, for example when a plant fault has occurred. The main idea is to spend some effort off-line on modeling the process, and from this model generate the control strategy, i.e. the plan. Here we present a planning tool implemented in a real-time expert system called G2. The planning system contains algorithms for creating plans in form of minimal GRAFCET charts that show maximal parallelism. The algorithms can handle a restricted class of problems and for this class the complexity only increases polynomially with the number of state variables.
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| 6. |
- Ljung, Lennart, 1946-, et al.
(författare)
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Identifiability Implies Robust Identifiability
- 1993
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Ingår i: Proceedings of the 32nd IEEE Conference on Decision and Control. - Linköping : Linköping University. - 0780312988 ; , s. 567-569 vol.1
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Konferensbidrag (refereegranskat)abstract
- In identification from a deterministic point of view an algorithm is said to be robustly convergent if the true system is regained when the noise level tends to zero. In this paper we introduce a concept close to this performance measure: robust global identifiability. A model structure, i.e. a smoothly parametrized set of models, is said to be robustly globally identifiable if there exist an identification algorithm such that the true parameters are regained when the noise level tends to zero. We show that global identifiability implies robust global identifiability when the model structure in consideration is a characteristic set of differential polynomials.
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| 7. |
- Ljung, Lennart, 1946-
(författare)
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Information Contents in Identification Data from Closed-Loop Operation
- 1993
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Ingår i: Proceedings of the 32th IEEE Conference on Decision and Control. - Linköping : Linköping University. - 0780312988 ; , s. 2248-2252 vol.3
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the light of the literature on “identification for control” we examine some asymptotic properties of models obtained by closed loop experiments. Essentially, it turns out that in many cases it is the input spectrum that determines the asymptotic properties, regardless if the input is realized in open or closed loop.
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| 8. |
- Ljung, Lennart, 1946-
(författare)
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Some Results on Identifying Linear Systems Using Frequency Domain Data
- 1993
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Ingår i: Proceedings of the 32nd IEEE Conference on Decision and Control. - Linköping : Linköping University. - 0780312988 ; , s. 3534-3538 vol.4
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The usefulness of frequency domain interpretations in linear systems is well known. In this contribution the connections between frequency domain and time domain expressions are discussed. In particular, the author considers some aspects of using frequency domain data as primary observations.
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| 9. |
- Medvedev, Alexander, et al.
(författare)
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On perfect disturbance rejection
- 1993
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Ingår i: Proceedings of the 32nd IEEE Conference on Decision and Control. - Piscataway, NJ : IEEE Communications Society. - 0780312988 ; , s. 1324-1329
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Konferensbidrag (refereegranskat)abstract
- A new observer-based approach to perfect disturbance rejection in linear continuous systems is introduced. A technique of continuous deadbeat observation is exploited to estimate the disturbance signal described by a known dynamic model. A realization condition in the form of linear algebraic equations is derived. It is shown that the introduced disturbance rejection scheme can be used in combination with any conventional control technique such as stabilization or servo control
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