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Overview of Current Indoor Positioning Systems

3rd BALTIC-SWISS GEODETIC SCIENCE WEEK, Sept. 10-12, 2008, Tallinn. Overview of Current Indoor Positioning Systems. Dr. Rainer Mautz ETH Zürich Institute of Geodesy and Photogrammetry.

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Overview of Current Indoor Positioning Systems

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  1. 3rd BALTIC-SWISS GEODETIC SCIENCE WEEK, Sept. 10-12, 2008, Tallinn Overview of Current Indoor Positioning Systems Dr. Rainer Mautz ETH Zürich Institute of Geodesy and Photogrammetry

  2. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Contents1. Positioning Requirements 2. Overview of Systems3. GNSS4. Alternative Positioning Systems5. Conclusions & Outlook

  3. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook dynamic all environments: indoors: household, office & factory outdoors: urban & rural User Requirements: availability: 100% of the time timeliness: realtime reliability: no failures hybrid systems: to be avoided local installations: none accuracy: mm - cm coverage: global

  4. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook • Classification of Positioning Systems: • Signal wavelength (Radio Frequencies, Light Waves, Ultrasound, RFID, Terahertz) • Principle (trilateration, triangulation, signal strength) • Environment (indoor, outdoor, urban, rural, remote) • Active / passive sensors • Accuracy (μm – km) • Application (industry, surveying, navigation)

  5. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Range 1 m 10 m 100 m 1 km 10 km Indoor Outdoor Accuracy 10 μm 100 μm 1 mm 1 cm 1 dm 1 m 10 m 100 m graphic: Rainer Mautz

  6. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Range 1 m 10 m 100 m 1 km 10 km Indoor Outdoor graphic: Rainer Mautz Accuracy 10 μm 100 μm 1 mm 1 cm 1 dm 1 m 10 m 100 m

  7. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Range 1 m 10 m 100 m 1 km 10 km Indoor Outdoor graphic: Rainer Mautz 10 μm 100 μm 1 mm 1 cm 1 dm 1 m 10 m 100 m Accuracy

  8. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Range Most Geodetic Applications 1 m 10 m 100 m 1 km 10 km Indoor Outdoor Most Geodetic Applications graphic: Rainer Mautz Accuracy 10 μm 100 μm 1 mm 1 cm 1 dm 1 m 10 m 100 m

  9. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook limitations: • in addition: • strong attenuation • fading: reflections, diffraction, scattering • no general model • no direct line-of-sight: • obstacles • multipath GNSS – Performance:

  10. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook gain number of satellites Number of satellites in space Today: 10 satellites (open sky) 2013: 40 satellites (open sky) Implications on indoor environments ? marginal Other improvements: integrity, anti-jam power, security, clocks!

  11. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Indoors: 100 times weaker underground: 10000 times weaker Attenuation of various building materials (L1 = 1500 MHz) Stone (1997) Signal Strength in Decibel Watt of GNSS Satellites

  12. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Assisted GNSS (AGNSS, AGPS) ephemeris, almanac via mobile phone (+) hot start, quicker position fix (-) long acquisition times indoors (-) high power needs for high sensitivity (-) accuracy degrades to m-level indoors How to overcome attenuation? • Increase receiver sensibility • Increase satellite signal power • Use ultra wideband GNSS signals graphic from: www.semsons.com

  13. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Alternative Positioning Systems Locata: Terrestrial pseudolite transceivers Picture from Barnes et al. (2003) 6thIinternational Symposium on Satellite Navigation Technology , Melbourne, Australia

  14. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Locata – Key Parameters: (+) RTK: 1 – 2 cm deviations at 2.4 m/s (+) signal magnitude stronger than GNSS (+) indoors dm Problem: multipath (low elevation) Picture from J. Barnes, C. Rizos, M. Kanli, A. Pahwa „A Positioning Technology for Classically Difficult GNSS Environments from Locata“, IEEE Conference, San Diego California, 26 April 2006

  15. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook iGPS iGPS transmitter and sensor during a test in a tunnel

  16. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook iGPS – “laser resection” • Key design: • two or more fixed transmitters • rotating fan-shaped laser beams • infrared signal • various sensors detect arrival times • position determination with spatial forward intersection graphic from Metris

  17. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook α Δt Localisation using direction of arrival • Key design: • mobile units are transmitters • min. 3 receiving units with 4 patch antennas each • accuracy currently 2 angular degrees • position determination with trilateration graphic from Fraunhofer Institute

  18. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Picture: Cambridge University Ultrasound Systems – Crickets, Active Bat, Dolphin

  19. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Ultrasound Systems – Crickets, Active Bat, Dolphin • Problems: • dependency on temperature • maximal range • deployment of reference beacons • multipath • reliability • interference with other sound sources

  20. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook Positioning based on Signal Strength • All signals can be used: • WLAN, Ultrasound, RF, GPRS, etc. • Problems: • reliability • accuracy Picture from: USC Robotics Research Lab

  21. Positioning Requirements Overview of Systems GNSS Alternative Positioning Systems Conclusions & Outlook ConclusionsOutdoors: GNSS dominating system for open-skyIndoors: No overall solution yetSeveral indoor systems on the market low accuracy sophisticated setups limited coverage area inadequate costsOutlook signals will penetrate buildings use existing infrastructure for higher accuracy are local installations unavoidableProject: Building own indoor positioning system!

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