| 1. |
- Nielsen, Lars, 1955-, et al.
(författare)
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Issues in Diagnosis, Supervision, and Safety
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Issues concerning diagnosis, supervision and saftey are found in many technologically advanced products. There is now a trend to extend the functionality of diagnosis and supervision systems to handle more advanced situations. This report collects some of the initiatives taking place in research and some of the developments taking place in the industry.
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| 2. |
- Gustafsson, Fredrik, 1964-, et al.
(författare)
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Best Choice of Coordinate System for Tracking Coordinated Turns
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A standard approach to tracking is to use the extended Kalman filter (EKF) applied to a nonlinear state-space model. We compare two conceivable choices of state variables for modeling civil aircrafts. One where Cartesian velocities are used and one where absolute velocity and heading angle are used. In both choices, Cartesian coordinates are used for position and angular velocity for turning. It is shown that the latter state vector always performs better. This is proven by considering the linearization error made in the extended Kalman filter applied either to a time-continuous model or a discretized model. The result is supported by a Monte Carlo simulation study.
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| 3. |
- Gustafsson, Fredrik, 1964-, et al.
(författare)
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Blind Equalization by Direct Examination of the Input Sequences
- 1995
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Ingår i: IEEE Transactions on Communications. - Linköping : Linköping University. - 0090-6778 .- 1558-0857. ; 43:7, s. 2213-2222
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a novel approach to blind equalization (deconvolution), which is based on direct examination of possible input sequences. In contrast to many other approaches, it does not rely on a model of the approximative inverse of the channel dynamics. To start with, the blind equalization identifiability problem for a noise-free finite impulse response channel model is investigated. A necessary condition for the input, which is algorithm independent, for blind deconvolution is derived. This condition is expressed in an information measure of the input sequence. A sufficient condition for identifiability is also inferred, which imposes a constraint on the true channel dynamics. The analysis motivates a recursive algorithm where all permissible input sequences are examined. The exact solution is guaranteed to be found as soon as it is possible. An upper bound on the computational complexity of the algorithm is given. This algorithm is then generalized to cope with time-varying infinite impulse response channel models with additive noise. The estimated sequence is an arbitrary good approximation of the maximum a posteriori estimate. The proposed method is evaluated on a Rayleigh fading communication channel. The simulation results indicate fast convergence properties and good tracking abilities.
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| 4. |
- Hjalmarsson, Håkan, 1962-, et al.
(författare)
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Composite modeling of transfer functions
- 1995
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - New Orleans, LA, USA : Institute of Electrical and Electronics Engineers (IEEE). - 0780326857 ; 40:5, s. 820-832
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Konferensbidrag (refereegranskat)abstract
- The problem under consideration is how to estimate the frequency function of a system and the associated estimation error when a set of possible model structures is given and when one of them is known to contain the true system. The 'classical' solution to this problem is to, firstly, use a consistent model structure selection criterium to discard all but one single structure. Secondly, estimate a model in this structure and, thirdly, conditioned on the assumption that the chosen structure contains the true system, compute an estimate of the estimation error. However, for a finite data set one cannot guarantee that the correct structure is chosen and this 'structural' uncertainty is lost in the previously mentioned approach. In this contribution a method is developed that combines the frequency function estimates and the estimation errors from all possible structures into a joint estimate and estimation error. Hence, this approach by-passes the structure selection problem. This is accomplished by employing a Bayesian setting.
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| 5. |
- Homer, John, et al.
(författare)
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Improved LMS Estimation via Structural Detection
- 1995
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Ingår i: Information Theory, 1995. Proceedings., 1995 IEEE International Symposium on.
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In various adaptive estimation applications, the unknown channel is characterized by an impulse response which consists of extended regions of negligible response or `inactivity'. We consider the LMS estimation of a channel that may be well approximated by an FIR (filter) model with only a few nonzero tap coefficients within a given delay horizon or tap length n. When the number of nonzero tap coefficients m is small compared to the delay horizon n, the performance of the LMS estimator is greatly enhanced when this specific structure is exploited. We propose a consistent algorithm that performs identification of nonzero taps only
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