The Challenges of Indoor Environments and Specification on some Alternative Positioning Systems

1. 6th Workshop on Positioning, Navigation and Communication (WPNC'09), 19.3.2009 The Challenges of Indoor Environments and Specification on some Alternative Positioning Systems Rainer Mautz ETH Zürich Institute of Geodesy and Photogrammetry

2. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Contents1. Overview of Systems2. GNSS3. Alternative Positioning Systems - Locata - iGPS - Ultrasound - CLIPS4. Conclusions & Outlook

3. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Range 1 m 10 m 100 m 1 km 10 km Indoor Outdoor Classification of Positioning Systems • Further classification by: • Signal wavelength (Radio Frequencies, Light Waves, Ultrasound, RFID, Terahertz) • Principle (trilateration, triangulation, signal strength) • Active / passive sensors • Application (industry, surveying, navigation) Accuracy 10 μm 100 μm 1 mm 1 cm 1 dm 1 m 10 m 100 m graphic: Rainer Mautz

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

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

6. Overview of Positioning 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:

7. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Indoors: 100 times weaker underground: 10000 times weaker Attenuation of various building materials (L1 = 1500 MHz) • How to overcome attenuation? • Increase receiver sensibility • Increase satellite signal power • Ultra wideband GNSS signals • Assisted GNSS Stone (1997) Signal Strength in Decibel Watt of GNSS Satellites

8. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Alternative Positioning Systems - Locata Terrestrial pseudolite transceivers, Locata Corporation in Canberra Augmentation for GNSS in urban canyons, pit mines, buildings Picture from Jonas BERTSCH: On-the-fly Ambiguity Resolution for the Locata Positioning System, Master Thesis, ETH Zurich, February 2009.

9. Overview of Positioning 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 Challanges: multipath (low elevation) Synchronisation < 30 pico-seconds 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

10. Overview of Positioning 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

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

12. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook iGPS Application of iGPS in a tunnel. Master Thesis, ETH Zurich by DAVID ULRICH: Innovative Positionierungs-systeme im Untertagebau, July 2008 Results Strengths: - High accuracy (0.1 mm) confirmed - Real-time, 40 Hz confirmed Problems: - Multipath - Influence of light sources

13. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Ultrasound Systems – Crickets, Active Bat, Dolphin • Method: • TOA, TDOA (ultrasound & RF) • Multilateration

14. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Ceiling Beacon Listener Floor Ultrasound Systems – Crickets Student Project: Robot Positioning • Problems: • dependency on temperature • maximal range • deployment of reference beacons • multipath • reliability • interference with other sound sources

15. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Optical Positioning Systems: ProCam System (AICON) • Mobile probe with CCD camera. • Spatial resection of measuring head. • relies on coded reference targets. (illuminated by an infrared flash) Pictures from: http://www.aicon.de

16. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook Optical Positioning Systems: CLIPS (Camera and Laser Indoor Positioning System) Production of laser “hedgehog”

17. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook CLIPS P3 P2 Principle: P5 P1 P4 Laser Pointer Hedgehog (fixed) basevector Camera (mobile) Probe (optional) Object

18. Overview of Positioning Systems GNSS Alternative Positioning Systems Conclusions & Outlook CLIPS Difficulties in detection of laser spots

19. Overview of Positioning 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 CLIPS: Building own indoor positioning system!

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