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Detecting Movement Type by Route Segmentation and Classification. Karol Waga , Andrei Tabarcea , Minjie Chen and Pasi Fränti. University of Eastern Finland. Joensuu. Joki = a river Joen = of a river Suu = mouth. Joensuu = mouth of a river. Motivation.
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Detecting Movement Type by Route Segmentation and Classification Karol Waga, Andrei Tabarcea,Minjie Chen and Pasi Fränti
University of Eastern Finland Joensuu Joki = a river Joen = of a river Suu = mouth Joensuu = mouth of a river
Trends and popularity of GPS Previous predictions Nokia: 50% of its smart phones has GPS by 2010-12. Gartner: 75%has GPS by the end of 2011. Nokia Android iPhone None
Trends and popularity of GPS Current situation Nokia: 50% of its smart phones has GPS by 2010-12. Gartner: 75%has GPS by the end of 2011. 70 % Our lab: Nokia 8 47 % Android 4 24 % iPhone 0 0 % None 5 30 %
Mopsi route collection4th October, 2012 173 users 7,958 routes 5,208,205 points
Collected GPS routeTime-vs-speed 14 12 10 What is the activity? 8 Speed (km/h) 6 4 2 Time
Features and classifiers Sensor data • GPS • GSM, WiFi • Accelerometers • Combination of multiple sensors Classification • Rule-based vs. trained • Fuzzy logic • Neural networks • Hidden Markov model
Run Walk Car Bicycle Boat Flight Bus Train Movement type classification Movement types considered: Other possibilities: Skiing Time tables Speed? Spatial contextneeded Track location, season
Rule-based! 2-order Hidden Markov model Problems attacked Problems addressed: • Training material is not always available • Problem of over-fit • Loss of generalization Limitations of current solution: • Correlation between neighboring segments • Accuracy of segmentation
Overall algorithm Optimal segmentation: • Minimize intra-segment speed variance • Detect stop segments Move type classification: • Speed features • 2-order Hidden Markov Model
Route segmentationDynamic programming Minimize intra-segment variance: Optimal segmentation: O(n2k)
2nd order Hidden Markov Model Previous segment Cost function: Next segment Cost function:
Long distance running Overall statisticsfrom running by move type
Interval training Intervals Stops Warm-up &slow-down
Bicycle trip represented as car Algorithm tries to be too clever
Skiing Boat Flight Bus Train Further improvements More move types Better stop detection Generate ground truth
Skiing Flight Train New movement types
Conclusions Method that (usually) works! Simple to implement No training data required