ClimbTheWorld: Real-time stairstep counting to increase physical activity

04 November 2014 MOBIQUITOUS 2014, London

ClimbTheWorld: Real-time stairstep counting to increase physical activity

Fabio Aiolli, Matteo Ciman, Michele Donini, Ombretta GaggiDepartment of Mathematics,

University of Padua, Italy{aiolli, mciman, mdonini, gaggi}@math.unipd.it

MOBIQUITOUS 2014, London

Health problem

04 November 2014 2 of 25


Wrong lifestyle


Sedentary life and bad nutrition are increasing overweight people

Increasing number of diseases like diabetes, cancer etc.

Higher medical costs


The Fun Theory


Piano Stairs experiment, Stockholm


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



ClimbTheWorld



Goals

Main features: Identify stairstep and distinguish them from

walking step


A stairstep A step


Goals


Main features: Identify stairstep and distinguish them from

walking step Support for (partial) orientation independence Segmentation vs Sliding windows Energy consumption analysis


Pipeline



Data standardization


DATA STANDARDIZATION


Orientation independence

Problem: accelerometer data changes depending on the orientation of the smartphone



Orientation Independence

First proposal: Mizell in 20031. Take a window of data of fixed time length2. Estimate the gravity component g=(gx , gy , gz)

averaging the readings of the window3. Calculate dynamic component as: d=(ax – gx , ay –

gy , az – gz) for every reading a=(ax , ay , az)4. Calculate vertical component p=5. Horizontal component h = d - p



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



Orientation independence Step 1, 2, 3 of gravity estimation and real

movement estimation are natively supported using the Linear sensor.


Our solution Native solution


Segmentation


TIME FILTER

NO_STAIR

MAYBE_STAIR

SEGMENTATION


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



Segmentation



Features & Classification


VECTORIAL REPRESENTATION

FEATURES STANDARDIZATIONCLASSIFICATION

STAIR or

NO_STAIR

COUNTING


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



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



Results


Mizell Linear Our Method



20Hz 30Hz 50Hz

0.65

0.7

0.75

0.8

0.85

0.9

F-score

DT KNN KOMD


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


Power Monitor to measure consumed energy


Energy consumption – Data Stand.


20Hz 30Hz 50Hz7200

7400

7600

7800

8000

8200

8400

8600

8800

9000

Energy Consumption (uAh)



Sliding window vs Segmentation


Sliding window Data segmentation11500

12000

12500

13000

13500

14000

14500

15000

Energy consumption (uAh)

About 1hour saved


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


04 November 2014 MOBIQUITOUS 2014, London

ClimbTheWorld: Real-time stairstep counting to increase physical activity

Fabio Aiolli, Matteo Ciman, Michele Donini, Ombretta GaggiDepartment of Mathematics,

University of Padua, Italy{aiolli, mciman, mdonini, gaggi}@math.unipd.it

Date post:	12-Feb-2017
Category:	Education
Upload:	university-of-geneva
View:	124 times
Download:	1 times

ClimbTheWorld: Real-time stairstep counting to increase physical activity

Education