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Reference/Citation: F. Aiolli, M. Ciman, M. Donini, O. Gaggi: "ClimbTheWorld: Real-time stairstep counting to increase physical activity", In Proceedings of the 11th International Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services (Mobiquitous 14), London, Great Britain, December 2014
ClimbTheWorld: Real-time stairstep counting to increase physical activity
1. 04 November 2014 MOBIQUITOUS 2014, London
ClimbTheWorld:
Real-time stairstep counting
to increase physical activity
Fabio Aiolli, Matteo Ciman, Michele Donini, Ombretta Gaggi
Department of Mathematics,
University of Padua, Italy
{aiolli, mciman, mdonini, gaggi}@math.unipd.it
3. Wrong lifestyle
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Sedentary life and bad nutrition are increasing
overweight people
Increasing number of diseases like diabetes,
cancer etc.
Higher medical costs
4. The Fun Theory
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Piano Stairs experiment, Stockholm
5. Related works
Use mobile and ubiquitous devices to tackle
portability issues
Many serious games, gamification systems and
activity recognition to incentivize people to live
more actively
Three main problems
Fixed position of the smartphone
High energy consumption
Not always in real-time
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7. Goals
Main features:
Identify stairstep and distinguish them from
walking step
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A stairstep A step
8. Goals
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Main features:
Identify stairstep and distinguish them from
walking step
Support for (partial) orientation independence
Segmentation vs Sliding windows
Energy consumption analysis
12. Orientation Independence
First proposal: Mizell in 2003
1. Take a window of data of fixed time length
2. Estimate the gravity component g=(gx , gy , gz)
averaging the readings of the window
3. Calculate dynamic component as: d=(ax – gx , ay
– gy , az – gz) for every reading a=(ax , ay , az)
4. Calculate vertical component p=
𝑑 ∙ 𝑚
𝑚 ∙ 𝑚
𝑚
5. Horizontal component h = d - p
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13. Orientation independence
1. We use a buffer of accelerometer data of the last
500ms
2. We estimate the gravity component g = (gx , gy ,
gz) as mean value of the buffer readings
3. We calculate the real movement d=(ax – gx , ay –
gy , az – gz);
4. Using data from the rotation sensor, we rotate d
into d’ to a fixed coordinate system
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14. Orientation independence
Step 1, 2, 3 of gravity estimation and real
movement estimation are natively supported using
the Linear sensor.
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Our solution Native
solution
16. Segmentation
A stair step has a specific pattern in
the fixed coordinate system
Instead of using sliding window, we
segment data
Energy reduction
Time becomes a feature
Easier learning task
User variability
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18. Features & Classification
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VECTORIAL
REPRESENTATION
FEATURES
STANDARDIZATION
CLASSIFICATION
STAIR
or
NO_STAIR
COUNTING
19. Features
Basic features to reduce
energy consumption
FFT coefficients could be
computationally
expensive
74 different values, like
average, STD, variance,
Signal Magnitude Area
For the Mizell approach,
features becomes
74x2 = 148
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20. Test
Data collected from 7 different users with their
own smartphone
8000 windows, 1500 stairsteps
We test Mizell method, Linear method and our
solution at three different frequencies: 20Hz, 30Hz
and 50Hz
Learning algorithms: Decision Tree, kNN and
KOMD
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21. Results
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0.65
0.7
0.75
0.8
0.85
0.9
Mizell Linear Our
Method
Mizell Linear Our
Method
Mizell Linear Our
Method
20Hz 30Hz 50Hz
F-score
DT KNN KOMD
22. Energy consumption
Energy consumption is a big problem and one of
the most important aspect for final users
The best approach is the one that combines low
energy and high precision
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Power Monitor to
measure consumed
energy
23. Energy consumption – Data Stand.
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7200
7400
7600
7800
8000
8200
8400
8600
8800
9000
20Hz 30Hz 50Hz
Energy Consumption (uAh)
Mizell Linear Our Method
24. Sliding window vs Segmentation
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11500
12000
12500
13000
13500
14000
14500
15000
Sliding window Data segmentation
Energy consumption (uAh)
About 1hour
saved
25. Conclusions
Real-time stairstep counter to increase physical
activity during everyday life
Main features
Partial support for orientation independence
Data segmentation for energy consumption reduction
Energy efficiency as key aspect of design
Future works:
Use history to increase overall precision of the system
Support for trousers pocket
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26. 04 November 2014 MOBIQUITOUS 2014, London
ClimbTheWorld:
Real-time stairstep counting
to increase physical activity
Fabio Aiolli, Matteo Ciman, Michele Donini, Ombretta Gaggi
Department of Mathematics,
University of Padua, Italy
{aiolli, mciman, mdonini, gaggi}@math.unipd.it