EasyTracker Automatic Transit Tracking, Mapping, and Arrival Time - - PowerPoint PPT Presentation
EasyTracker Automatic Transit Tracking, Mapping, and Arrival Time - - PowerPoint PPT Presentation
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
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We love bus trackers!
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Winter in Chicago
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Our shuttle web (before)
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Our shuttle web (before)
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Our shuttle web (after)
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One service for everyone
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Our shuttle web
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Our shuttle web
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This paper in a nutshell
- Automatic generation of
- route shapes
- stop locations
- schedules
- Online processing for
- vehicle-to-route classification
- arrival-time prediction
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EasyTracker installation
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EasyTracker installation
- 1. Obtain smartphone
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EasyTracker installation
- 1. Obtain smartphone
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- 2. Install EasyTracker app
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EasyTracker installation
- 1. Obtain smartphone
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- 2. Install EasyTracker app
- 3. Stick phone in bus
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- 4. Relax
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System overview
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GPS GPS
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System overview
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GPS GPS
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Batch processing
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Batch processing
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Raw GPS traces
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Route map
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Raw GPS traces
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Kernel Density Estimation
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Kernel Density Estimation
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Kernel Density Estimation
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Kernel Density Estimation
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K(x) = 1 √ 2πσ2 e− x2
2σ2
Kernel density estimation
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ˆ f(x) = 1 n
n
X
i=1
K(x − xi)
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2-D histogram
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Trajectory density estimate
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Thresholded image
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- Davies et al., 2006
Map extraction
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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
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction
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Route extraction results
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Welch’s t-Test
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0.008 0.015 0.023 0.030 P-value
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Routes separated
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Real Routes Spurious Routes
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Stop extraction
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Route-labeled GPS traces
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2-D histogram
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Point density estimate
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Thresholded binary image
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Noise in binary image
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Noise reduced binary image
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Stop extraction
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Stop extraction
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Stop extraction performance
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Schedule extraction
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Bus stop arrival times
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Bus stop arrival times
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Bus stop arrival times
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Bus stop arrival times
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Bus stop arrival times
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Bus stop arrival times
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First stop schedule
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Travel time variance
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Last stop arrival times
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travel time(1, j, t) = 1 |D| X
D
at
j − at 1
Compute mean travel times
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Compute downstream schedules
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kj
t = k1 t + travel time(1, j, t)
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Last stop arrival times
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Last stop schedule
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Schedule accuracy
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Schedule accuracy
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System architecture
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Online processing
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Online processing
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Un-classified buses
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Classified buses
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Hidden Markov model
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Classification accuracy
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Classification delay
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Classification delay
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Arrival time prediction
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Predicting arrival times
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time until arrival(si) = γtravel time(sprev+1, si)+ (1 − γ)travel time(sprev, si)
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Arrival time predictions
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Schedule vs. real-time
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Schedule vs. real-time
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Schedule vs. real-time
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System overview
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GPS GPS
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Come and see our demo!
- Thursday, 3:30p-7:30p
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