EasyTracker Automatic Transit Tracking, Mapping, and Arrival Time Prediction Using Smartphones James Biagioni, Tomas Gerlich, Timothy Merrifield and Jakob Eriksson
We love bus trackers! slide 2
Winter in Chicago slide 3
Our shuttle web (before) slide 4
Our shuttle web (before) slide 4
Our shuttle web (after) slide 5
One service for everyone slide 6
Our shuttle web slide 7
Our shuttle web slide 7
This paper in a nutshell ‣ Automatic generation of - route shapes - stop locations - schedules ‣ Online processing for - vehicle-to-route classification - arrival-time prediction slide 8
EasyTracker installation slide 9
EasyTracker installation 1. Obtain smartphone slide 9
EasyTracker installation 1. Obtain smartphone 2. Install EasyTracker app slide 9
EasyTracker installation 1. Obtain smartphone 2. Install EasyTracker app 3. Stick phone in bus slide 9
4. Relax slide 10
System overview GPS GPS slide 11
System overview GPS GPS slide 11
Batch processing slide 12
Batch processing slide 12
Raw GPS traces slide 13
Route map slide 14
Raw GPS traces slide 15
Kernel Density Estimation slide 16
Kernel Density Estimation slide 16
Kernel Density Estimation slide 16
Kernel Density Estimation slide 16
Kernel density estimation n f ( x ) = 1 ˆ X K ( x − x i ) n i =1 1 2 πσ 2 e − x 2 K ( x ) = 2 σ 2 √ slide 17
2-D histogram slide 18
Trajectory density estimate slide 19
Thresholded image slide 20
Map extraction ‣ Davies et al., 2006 slide 21
Route extraction ‣ Map match GPS traces - Viterbi-based map matching - based on Thiagarajan, et al. 2009 ‣ Extract common routes - edge subsequence matching - statistical test removes spurious results slide 22
Route extraction slide 23
Route extraction slide 23
Route extraction slide 23
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction slide 24
Route extraction results slide 25
Welch’s t -Test 0.030 0.023 P-value 0.015 0.008 0 slide 26
Routes separated Real Routes Spurious Routes slide 27
Stop extraction slide 28
Route-labeled GPS traces slide 29
2-D histogram slide 30
Point density estimate slide 31
Thresholded binary image slide 32
Noise in binary image slide 33
Noise reduced binary image slide 34
Stop extraction slide 35
Stop extraction slide 36
Stop extraction performance slide 37
Schedule extraction slide 38
Bus stop arrival times slide 39
Bus stop arrival times slide 39
Bus stop arrival times slide 39
Bus stop arrival times slide 39
Bus stop arrival times slide 39
Bus stop arrival times slide 40
First stop schedule slide 41
Travel time variance slide 42
Last stop arrival times slide 43
Compute mean travel times 1 X a t j − a t travel time (1 , j, t ) = 1 | D | D slide 44
Compute downstream schedules k j t = k 1 t + travel time (1 , j, t ) slide 45
Last stop arrival times slide 46
Last stop schedule slide 47
Schedule accuracy slide 48
Schedule accuracy slide 48
System architecture slide 49
Online processing slide 50
Online processing slide 50
Un-classified buses slide 51
Classified buses slide 52
Hidden Markov model slide 53
Classification accuracy 1.0 0.8 0.6 0.4 0.2 0 Correct Incorrect Unclassified slide 54
Classification delay slide 55
Classification delay slide 55
Arrival time prediction slide 56
Predicting arrival times time until arrival ( s i ) = γ travel time ( s prev +1 , s i )+ (1 − γ ) travel time ( s prev , s i ) slide 57
Arrival time predictions slide 58
Schedule vs. real-time slide 59
Schedule vs. real-time slide 59
Schedule vs. real-time slide 59
System overview GPS GPS slide 60
Come and see our demo! ‣ Thursday, 3:30p-7:30p slide 61
Thanks! Questions?
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