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Ubiquitous Care System to Support Independent Living : Preliminary Results

by Boštjan Kaluža, Violeta Mirčevska, Mitja Luštrek, Igone Velez, Matjaž Gams
Machine Learning (2009)

Abstract

The European FP7 project CONFIDENCE - Ubiquitous Care System to Support Independent Living is developing a system that will monitor the health conditions of the elderly in real-time based on radio tags placed on the human body. In case of health problems, the system will issue a warning to the user and an alarm to the caregiver if necessary. This way the elderly should gain the needed con dence and security to continue their independent participation in society, thus reducing costs for medical services and burden to the working age pop- ulation. The paper describes work in progress of the reconstruction and interpretation subsystem and presents encouraging results in complexfall detection scenario.

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Ubiquitous Care System to Support Independent Living : Preliminary Results

Ubiquitous Care System to Support
Independent Living: Preliminary
Results
Boštjan Kaluža1,
Violeta Mirčevska1, Mitja Luštrek1, Igone Vélez2,
and Matjaž Gams1
1 Department of Intelligent Systems, Jožef Stefan Institute, Slovenia
2 Centro de Estudios e Investigaciones Técnicas de Gipuzkoa, Spain
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Outline
1. The CONFIDENCE project
2. Reconstruction and interpretation
subsystem
3. Evaluation and results
4. Conclusion
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The CONFIDENCE project
• FP 7 project
• 10 partners
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The CONFIDENCE project
• Primary goal: create care system able to
detect abnormal situations
– Short term, e.g., fall
– Long term, e.g., gait disorders
• When hazardous situation
– Trigger alarm
– Call relatives or help center
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The CONFIDENCE hardware
• Equipment
– Small body-worn tags
• Wireless
• 3D coordinates
– Central device
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The CONFIDENCE project
• General structure of the system
Localization
Subsystem
Reconstruction
and Interpretation
Subsystem
System Interface
Subsystem
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The CONFIDENCE project
• General structure of the system
Localization
Subsystem
Reconstruction
and Interpretation
Subsystem
System Interface
Subsystem
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Reconstruction and Interpretation Subsystem
(RIS)
• Main tasks:
– Posture reconstruction
– Activity recognition
– Fall detection
– Disability/disease
detection
V. Mirčevska and B. Kaluža. Towards Intelligent Home Caregiver. In Proceedings of the 1st Jožef Stefan International
Postgraduate School Student’s Conference, Ljubljana, Slovenia, May 2009.
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RIS: Architecture
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RIS: Preprocessing
• Noisy data
• Three steps:
– Median filter
– Anatomic
constraints
– Kalman filtering
B. Kaluža and E. Dovgan. Glajenje trajektorij gibanja človeškega telesa zajetih z radijsko tehnologijo.
IS 2009, Ljubljana, Slovenia, October 2008.
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RIS: Attribute Computation
Reference coordinate system
• z coordinates
• absolute velocities, z velocities
• absolute distances between tags,
z distances
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RIS: Attribute Computation
Reference coordinate system
Body coordinate system
• z coordinates
• absolute velocities, z velocities
• absolute distances between tags,
z distances
• x, y, z coordinates
• absolute velocities,
x, y, z velocities
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RIS: Attribute Computation
• z coordinates
• absolute velocities, z velocities
• absolute distances between tags,
z distances
• x, y, z coordinates
• absolute velocities,
x, y, z velocities
Reference coordinate system
Body coordinate system
Angles
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RIS: Activity Recognition
• Two approaches:
– Machine learning
– Expert rules
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RIS: Activity Recognition with Machine
Learning
t
Snapshot
Snapshot
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RIS: Activity Recognition with Machine
Learning
t-1 t t-2 t-9 ...
Activity
Feature vector
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RIS: Activity Recognition with Machine
Learning
t-1 t t-2 t-9 ...
Activity
t+1
t+2
t+3
...
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RIS: Activity Recognition with Machine
Learning
t-1 t t-2 t-9 ...
Activity
t+1
t+2
t+3
...
Feed machine learning algorithm
M. Luštrek and B. Kaluža. Fall Detection and Activity Recognition with Machine Learning. Informatica, 33(2):197-204, 2009.
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RIS: Activity Recognition with Machine
Learning
M. Luštrek, B. Kaluža, E. Dovgan, B. Pogorelc and M. Gams. Behavior Analysis Based on Coordinates of Body Tags. AmI 2009.
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RIS: Activity Recognition Example
No noise: sitting down Noise: falling
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RIS: Activity Recognition with Expert Rules
• Common sense rules
• Rule induction from decision trees
IF
 DistZ(ankle,
 chest)
 <
 0.3
 AND
 DistXY(ankle,
 chest)
 >
 1.2
 

 
 
 
 AND
 ABS(Vz(chest)
 )
 <
 0.02
 
 
THEN
 LYING
 
IF
 DistZ(ankle,
 chest)
 <
 0.2
 AND
 ABS(Vz(chest))
 <
 0.02
 
 
THEN
 LYING
 
IF
 DistZ(ankle,
 chest)
 >
 1.2
 AND
 DistXY(ankle,
 chest)
 <
 0.35
 

 
 
 
 AND
 Vz(chest)
 >
 -­‐0.07
 
 
THEN
 STANDING
 
IF
 Vz(chest)
 <
 -­‐0.15
 
 
THEN
 FALLING
 
V. Mirčevska, M. Luštrek, M. Gams. Combining Machine Learning and Expert Knowledge for Classifying Human Posture.ERK 2009, September, Portoroz-Slovenia.
V. Mircevska, M.Lustrek, I.Velez, N. González, M.Gams. Classifying Posture Based on Location of Radio Tags. AMIF-Ambient Intelligence Forum-Czech Republic, September, 2009.
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RIS: Detection of Critical Situations
• Arise from sudden health problems
– Tripping
– Fainting
– Falling from chair
• Reflected by activity sequence
• Implemented with expert rules
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RIS: Detection of Disability/Disease Detection
• Illness reflected in daily life activities
• Statistical methods
– Monitor walking characteristics
– Behavioral changes
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Evaluation
• 4 tags attached to person
– Belt, chest, left/right ankle
– Ubisens RTLS
• Complex scenario including
– Three falls
– Three false alarms
• Data
– 5 people
– Each preformed scenario 5 times
• Evaluation: leave-one-person-out
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Evaluation
Youtube: http://www.youtube.com/watch?v=r9gSUn9RPgk or keywords confence prototype.
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Results
Case Machine learning
accuracy [%]
Expert rules accuracy
[%]
Tripping 100 96
Fainting standing 88 92
Sliding from the chair 56 40
Jumping in bed 100 100
Sitting down quickly 100 96
Searching under a table/bed 96 72
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Conclusion
• Aim:
Prolong independency of the elderly
– Detecting falls, health problems
• RIS
– Several modules in pipeline
– Machine learning + expert knowledge
• Preliminary results promising
– Detecting complex fall scenarios

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