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WalkCompass: I am a Smartphone and I can Tell my Users Walking - PowerPoint PPT Presentation

Apr 29, 2023 •17 likes •537 views

WalkCompass: I am a Smartphone and I can Tell my Users Walking Direction MobiSys 2014, Bretton Woods, NH Nirupam Roy He Wang Romit Roy Choudhury ! ! Indoor Localization: Chasing Accuracy Location Accuracy 2 Meter 50 Centimeter 3 Meter

  1. WalkCompass: I am a Smartphone and I can Tell my User’s Walking Direction MobiSys 2014, Bretton Woods, NH Nirupam Roy He Wang Romit Roy Choudhury ! !

  2. Indoor Localization: Chasing Accuracy Location Accuracy 2 Meter 50 Centimeter 3 Meter 1 Meter Mean 2000 2004 2007 2010 2013

  3. Indoor Localization: Chasing Accuracy Location Accuracy 2 Meter 50 Centimeter 3 Meter 1 Meter Mean 95 th Percentile 2000 2004 2007 2010 2013

  5. Hardware Walking Map/ Step Device Homogeneity Direction Floor plan Length Orientation …

  6. Walking Direction

  7. Walking Direction: The Definition Walking Direction 8!

  8. Walking Direction: The Definition 9!

  9. Why Not Compass ? 10!

  10. Why Not Compass? Y axis 60° NE N 60° NE

  11. Why Not Compass? Y axis Y axis 30° NE 60° NE N N 60° NE 12!

  12. Why Not Compass? Y axis Y axis 60° NE 30° NE N N Walking Direction Walking Direction 60° NE 13!

  13. Why Not Compass? Compass Direction �� Walking Direction 14!

  14. Walking Direction Force Force 15!

  15. Challenges 16!

  16. Challenge 1: Finding the Right Force Complex combination of forces 17!

  17. Challenge 2: Finding Common Solution Different walking patterns Different phone locations 18!

  18. Understanding a Walk Signal Raw accelerometer signal Phone Location: Pants pocket 19!

  19. Understanding a Walk Signal Foot!step! Body!movement! Leg!touches! ground! Leg!swing! Raw accelerometer signal Phone Location: Pants pocket 20!

  20. Segmentation of the Signal: Key Intuition 21!

  21. Technique Overview 22!

  22. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) Heel-touch Heel-touch Heel-touch (Right) (Left) (Right) 23! Raw Accelerometer Signal

  23. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) Heel-touch Heel-touch Heel-touch (Right) (Left) (Right) 24! High Frequency Components

  24. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) Heel-touch Heel-touch Heel-touch (Right) (Left) (Right) 25! Heel-touch Detection Signal

  25. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) 26! Raw Accelerometer Signal

  26. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) 27! Low Frequency Components

  27. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) 28!

  28. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) 29!

  29. Anatomy of a Human Walk Swing Phase (40%) Stance Phase (60%) 30!

  30. Walking Direction Vector W 3D 31!

  31. Walking Direction Vector W 3D Y W 2D 32!

  32. Global Walking Direction 60° North-East W 2D 33!

  33. But… 34!

  34. Global Walking Direction W 2D 35!

  35. Compass: How Reliable is this? 36!

  36. Compass Correction 37!

  37. Compass: How It Works N S 38!

  38. Compass: Effect of Interference N Ferromagnetic Material S 39!

  39. Compass: Effect of Interference N Ferromagnetic Material S 40!

  40. Compass: Effect of Interference N R esultant I nterference G eo-mag R = G + I - G = I R 41!

  41. Iterative Magnetic Triangulation (IMT) 42!

  42. Iterative Magnetic Triangulation (IMT) - = G correct R I R G correct I 43!

  43. Iterative Magnetic Triangulation (IMT) - = G incorrect R I R G incorrect I 44!

  44. Evaluation 45!

  45. Methodology

  46. Error in Walking Direction 150 Absolute Error (degree) Median 75th Percentile 100 50 0 0 10 20 30 Number of Steps 47!

  47. Error in Walking Direction 150 Absolute Error (degree) Median 75th Percentile 100 Error!converges!to!8°!! within!6!steps! 50 0 0 10 20 30 Number of Steps 48!

  48. Better Compass 90 90 120 60 120 60 150 30 150 30 180 0 180 0 210 330 210 330 240 300 240 300 270 270 Today’s Corrected Compass Compass (IMT Algorithm) 49!

  49. Better Compass 90 90 120 60 120 60 150 30 150 30 180 0 180 0 Error!±40°! Error!±10°! 210 330 210 330 240 300 240 300 270 270 Today’s Corrected Compass Compass (IMT Algorithm) 50!

  50. Discussion and Future Work - Convergence time of the system - Performance when the phone is in a bag 51!

  51. Conclusion 52!

  52. Thank You. SyNRG!@!UIUC! hCp://synrg.csl.illinois.edu! hCp://synrg.csl.illinois.edu/projects/localizaSon/ walkcompass!

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