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Topics in Localization and Mapping
Linköping University, Department of Electrical Engineering, Automatic Control.
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The need to determine ones position is common and emerges in many different situations. Tracking soldiers or a robot moving in a building or aiding a tourist exploring a new city, all share the questions ”where is the unit?“ and ”where is the unit going?“. This is known as the localization problem.Particularly, the problem of determining ones position in a map while building the map at the same time, commonly known as the simultaneous localization and mapping problem (slam), has been widely studied. It has been performed in cities using different land bound vehicles, in rural environments using au- tonomous aerial vehicles and underwater for coral reef exploration. In this thesis it is studied how radar signals can be used to both position a naval surface ves- sel but also to simultaneously construct a map of the surrounding archipelago. The experimental data used was collected using a high speed naval patrol boat and covers roughly 32 km. A very accurate map was created using nothing but consecutive radar images.A second contribution covers an entirely different problem but it has a solution that is very similar to the first one. Underwater sensors sensitive to magnetic field disturbances can be used to track ships. In this thesis, the sensor positions them- selves are considered unknown and are estimated by tracking a friendly surface vessel with a known magnetic signature. Since each sensor can track the vessel, the sensor positions can be determined by relating them to the vessel trajectory. Simulations show that if the vessel is equipped with a global navigation satellite system, the sensor positions can be determined accurately.There is a desire to localize firefighters while they are searching through a burn- ing building. Knowing where they are would make their work more efficient and significantly safer. In this thesis a positioning system based on foot mounted in- ertial measurement units has been studied. When such a sensor is foot mounted, the available information increases dramatically since the foot stances can be de- tected and incorporated in the position estimate. The focus in this work has therefore been on the problem of stand still detection and a probabilistic frame- work for this has been developed. This system has been extensively investigated to determine its applicability during different movements and boot types. All in all, the stand still detection system works well but problems emerge when a very rigid boot is used or when the subject is crawling. The stand still detection frame- work was then included in a positioning framework that uses the detected stand stills to introduce zero velocity updates. The system was evaluated using local- ization experiments for which there was very accurate ground truth. It showed that the system provides good position estimates but that the estimated heading can be wrong, especially after quick sharp turns.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2011. , 69 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1489
Keyword [en]
sensor fusion
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:liu:diva-72575Local ID: LiU-TEK-LIC-2011:28ISBN: 978-91-7393-152-6OAI: diva2:459882
2011-05-06, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2011-11-29 Created: 2011-11-28 Last updated: 2011-11-29Bibliographically approved
List of papers
1. RADAR SLAM using Visual Features
Open this publication in new window or tab >>RADAR SLAM using Visual Features
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2011 (English)In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2011, no 71Article in journal (Refereed) Published
Abstract [en]

A vessel navigating in a critical environment such as an archipelago, requires very accurate movement estimates. Intentional or unintentional jamming makes gps unreliable as the only source of information and an additional independent navigation system should be used. In this paper we suggest estimating the vessel movements using a sequence of radar images from the preexisting body-fixed radar. Island landmarks in the radar scans are tracked between multiple scans using visual features. This provides information not only about the position of the vessel but also of its course and velocity. We present here a complete navigation framework that requires no additional hardware than the already existing naval radar sensor. Experiments show that visual radar features can be used to accurately estimate the vessel trajectory over an extensive data set.

Place, publisher, year, edition, pages
Springer, 2011
GPS, Navigation system, Radar, Sensor
National Category
Control Engineering
urn:nbn:se:liu:diva-72583 (URN)10.1186/1687-6180-2011-71 (DOI)000300999900001 ()
Swedish Foundation for Strategic Research Swedish Research Council

funding agencies|Strategic Research Center MOVIII||Swedish Foundation for Strategic Research||SSF||CADICS||Swedish Research Council||

Available from: 2011-11-29 Created: 2011-11-29 Last updated: 2013-07-23Bibliographically approved
2. Silent Localization of Underwater Sensors Using Magnetometers
Open this publication in new window or tab >>Silent Localization of Underwater Sensors Using Magnetometers
2010 (English)In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2010, no 1Article in journal (Refereed) Published
Abstract [en]

Sensor localization is a central problem for sensor networks. If the sensor positions are uncertain, the target tracking ability of the sensor network is reduced. Sensor localization in underwater environments is traditionally addressed using acoustic range measurements involving known anchor or surface nodes. We explore the usage of triaxial magnetometers and a friendly vessel with known magnetic dipole to silently localize the sensors. The ferromagnetic field created by the dipole is measured by the magnetometers and is used to localize the sensors. The trajectory of the vessel and the sensor positions are estimated simultaneously using an Extended Kalman Filter (EKF). Simulations show that the sensors can be accurately positioned using magnetometers.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2010
Underwater sensor localization, Sensor network, Magnetometers, SLAM
National Category
Signal Processing Control Engineering
urn:nbn:se:liu:diva-53589 (URN)10.1155/2010/709318 (DOI)000274966500001 ()
Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2014-09-30Bibliographically approved

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