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M. Troger, C. Fösleitner, J. Seybold TeleConsult Austria GmbH, Austria

GNSS/INS Integration using a Tightly Coupled Approach for Navigation of People with Visual Impairments. M. Troger, C. Fösleitner, J. Seybold TeleConsult Austria GmbH, Austria European Navigation Conference 2013 23 rd – 25 th April 2013 Vienna, Austria. Motivation (1/2).

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M. Troger, C. Fösleitner, J. Seybold TeleConsult Austria GmbH, Austria

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  1. GNSS/INS Integration using a Tightly Coupled Approach for Navigation of People with Visual Impairments M. Troger, C. Fösleitner, J. Seybold TeleConsult Austria GmbH, Austria European Navigation Conference 2013 23rd – 25th April 2013 Vienna, Austria

  2. Motivation (1/2) • Navigation of pedestrian through GNSS • Position is determined by means of GNSS • Route to the destination point (track point) is calculated • Manoeuvring list is generated • Visually guidance to the track point through Smartphone screen • How to proceed, if the pedestrian is visually impaired? ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  3. Motivation (2/2) • Navigation of visually impaired people • Determination of position • Binaural sounds generated • Depending on user’s position • Depending on user’s heading • Depending on position of track point • Binaural sounds provided to user through stereo-headphone • Requirements: • High accuracy and availability of position • High availability of heading • Fusion between GNSS and INS sensors • Different properties of both systems qualify them for combined use • Kalman Filter  optimal tool for fusion ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  4. Contents • Loosely vs. tightly coupling • Tightly coupled approach • Parameters of the state • Measurement updates • Dynamic model • Dynamic test and results • Conclusion and future work ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  5. Loosely vs. tightly coupling Loosely coupling Tightly coupling • Advantage of tightly coupling: GNSS measurements can be used if less than four satellites are visible! ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  6. Tightly coupled approach (1/4) • Parameters of the state vector • ECEF position • ECEF velocity • Distance error caused by receiver clock error • Velocity error caused by receiver clock drift • Quaternion vector • Biases of the gyroscopes ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  7. Tightly coupled approach (2/4) • Measurement update: GNSS observations • Code pseudoranges • Corrected due to ionosphere, troposphere, and satellite clock error • Elevation based measurement noise • Doppler • Measurement noise indirect proportional to SNR ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  8. Tightly coupled approach (3/4) • Measurement update: Velocity • Derivation of step frequency using autocorrelation of acceleration measurements • Computation of horizontal velocity with step length and step length variation parameter • Measurement update: Bias of angular rates • During phases without rotation and without movements • Identification of phases using inertial measurements ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  9. Tightly coupled approach (4/4) • Time update • Model of uniform motion • Angular rates and gyro biases are introduced into dynamic coefficient matrix ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  10. Dynamic test and results (1/3) • Positioning unit was fixed tightly onto the belt at the back of a test person • Low-cost GPS L1 receiver with raw data output • Code pseudoranges, Doppler (Output rate: 1 Hz) • Navigation Message • IMU with low-cost characteristics • Angular rates, accelerations (Output rate: 20 Hz) • Synchronisation and storage of measurements on micro-processor board  sensor fusion in post-processing • Reference trajectory based only on GPS observations processed by means of Kalman filtering in real-time (1 Hz) • Initial alignment at the beginning of the dynamic test • Roll and pitch  from accelerations during static phase • Heading  from GPS during dynamic phase • Default step length of user ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  11. Dynamic test and results (2/3) Horizontal positions without GPS outage Heading without GPS outage Horizontal positions with simulated GPS outage (35 s) Heading with simulated GPS outage (35 s) ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  12. Dynamic test and results (3/3) • Overview of trajectories overlaid with GoogleTM Earth Horizontal positions overlaid with GoogleTM Earth

  13. Conclusion and future work • Conclusion • Kalman Filter approach shows potential in area of pedestrian navigation • GPS outages can be bridged over short time interval • Heading information is usable for binaural guidance • Future work • Find the optimal weighting between measurement noise and system noise • Software integration for real time operation • Online step length derivation • Refinement of bias update ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  14. Acknowledgement • The research work described was conducted within the project ARGUS, which is co-funded by the EU Seventh Framework Programme under grant FP7-288841(ARGUS). ENC 2013, April 23rd - 25th 2013 - Vienna, Austria

  15. Markus Troger Senior Systems Engineer E-MAIL mtroger@tca.at WEB www.tca.at PHONE +43-316-890971-11 FAX +43-316-890971-55

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