| 1. |
- Andersson, Sören, et al.
(författare)
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Analysis of a polarized seismic wave model
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We present a model for polarized seismic waves where the data are collected by three-component geophone receivers. The model is based on two parameters describing the polarization properties of the waveforms. These parameters are the ellipticity and the orientation angle of the polarization ellipse. The model describes longitudinal waveforms (P-waves) as well as elliptically polarized waves. For the latter waves the direction-of-propagation of the waveform is in the plane spanned by the ellipse's major and minor axes; Rayleigh waves are treated as a special case. We analyze the identifiability of the models and derive the Cramer-Rao and mean-square-angular-error (MSAE) bounds involving one or two three-component geophones.
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| 2. |
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| 3. |
- Andersson, Sören, et al.
(författare)
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Optimal Dimension Reduction for Array Processing : Generalized
- 1993
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This correspondence extends previously reported work [1, 2] on the problem, or rather possibility, of achieving optimality of beamspace (BS) array processing, where use is made of dimensionally reduced data vectors. The optimality here is with respect to the best possible element space (ESP) parameter estimation accuracy, i.e., the Cramér-Rao bound.
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| 4. |
- Andersson, Sören, et al.
(författare)
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Some Comparisons of Cramer-Rao Bounds for Vector Sensors and Scalar Sensor Arrays for Array Processing
- 1993
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The effect from polarization of emitted wave fronts on the parameter estimation accuracy for an array composed only of sensors sensitive to just one polarization direction has not been addressed in the literature this far. Antennas with such characteristics are, e.g., dipole (or scalar) antennas. A vector sensor, on the other hand, is a sensor whose output data consists of, for the electromagnetic case, the complete electric and magnetic fields at the sensor. This paper examines some of the effects on the Cram'er-Rao Bound for the elevation and/or azimuth angles to a single source emitting a polarized (electromagnetic) waveform. Since only one vector sensor is needed for estimation of both azimuth and elevation, it would be of interest to compare the lower parameter estimation error bound resulting from the vector sensor data model to the "ordinary" one, i.e. the data model used for scalar arrays. Such comparisons, both analytically and numerically, are herein made for an acoustic data model, as well as for an electromagnetic measurement model, for some simple scenarios and array configurations.
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| 5. |
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| 6. |
- Ottersten, Björn, et al.
(författare)
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Exact and Large Sample ML Techniques for Parameter Estimation and Detection in Array Processing
- 1993
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Ingår i: Radar Array Processing. - Berlin ; New York : Springer Berlin/Heidelberg. - 3540552243 - 9783540552246 - 0387552243 - 9780387552248 ; , s. 99-151
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Bokkapitel (refereegranskat)abstract
- Sensor array signal processing deals with the problem of extracting information from a collection of measurements obtained from sensors distributed in space. The number of signals present is assumed to be finite, and each signal is parameterized by a finite number of parameters. Based on measurements of the array output, the objective is to estimate the signals and their parameters. This research area has attracted considerable interest for several years. A vast number of algorithms has appeared in the literature for estimating unknown signal parameters from the measured output of a sensor array.
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| 7. |
- Ottersten, Björn, et al.
(författare)
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Exact and Large Sample ML Techniques for Parameter Estimation and Detection in Array Processing
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sensor array signal processing deals with the problem of extracting information from a collection of measurements obtained from sensors distributed in space. The number of signals present is assumed to be finite, and each signal is parameterized by a finite number of parameters. Based on measurements of the array output, the objective is to estimate the signals and their parameters. This research area has attracted considerable interest for several years. A vast number of algorithms has appeared in the literature for estimating unknown signal parameters from the measured output of a sensor array.
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| 8. |
- Prateek, G. V, et al.
(författare)
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Modeling, Detecting, and Tracking Freezing of Gait in Parkinson Disease Using Inertial Sensors
- 2018
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Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9294 .- 1558-2531. ; 65:10, s. 2152-2161
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Tidskriftsartikel (refereegranskat)abstract
- In this paper. we develop new methods to automatically detect the onset and duration of freezing of gait (FOG) in people with Parkinson disease (PD) in real time, using inertial sensors. We first build a physical model that describes the trembling motion during the FOG events. Then, we design a generalized likelihood ratio test framework to develop a two-stage detector for determining the zero-velocity and trembling events during gait. Thereafter, to filter out falsely detected FOG events, we develop a point-process filter that combines the output of the detectors with information about the speed of the foot, provided by a foot-mounted inertial navigation system. We computed the probability of FOG by using the point-process filter to determine the onset and duration of the FOG event. Finally, we validate the performance of the proposed system design using real data obtained from people with PD who performed a set of gait tasks. We compare our FOG detection results with an existing method that only uses accelerometer data. The results indicate that our method yields 81.03% accuracy in detecting FOG events and a threefold decrease in the false-alarm rate relative to the existing method.
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| 9. |
- Skog, Isaac, et al.
(författare)
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Arrays of single-chip IMUs
- 2015
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Ingår i: Proc. International Conference on Indoor Positioning and Indoor Navigation (IPIN). - Calgary, Canada : University of Calgary.
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Konferensbidrag (refereegranskat)abstract
- The development of ultralow-cost single-chip IMUs nowmake it feasible to construct massive IMU arrays. Such arrays giveproperties not attainable by single IMUs. Specifically, non-colocatedaccelerometers provide rotational information with complementary char-acteristics to that provided by the gyroscopes. In this poster we reviewthe signal model of multi-IMU systems and present experimental resultsfrom an in-house developed IMU array.
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| 10. |
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