using a triaxial accelerometer for movement monitoring presenter: chang-yu tsai adviser: cheng- jui...

Using a Triaxial Accelerometer forMovement Monitoring

Presenter: Chang-Yu Tsai

Adviser: Cheng- Jui Hung

2009/11/23

2009/11/232

Outline

Introduction

Papers review

Future works

References

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Introduction

Triaxial accelerometer applications for a Behavior Monitoring Systems.

Advantages of MEMS Triaxial accelerometer ： Low cost. High precision. Small volume. Low power.

MEMS: Microelectromechanical Systems ( 微機電系統 )

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Papers review

[1] Dean M. Karantonis, Michael R. Narayanan, Merryn Mathie, Nigel H. Lovell, Branko G. Celler ,“Implementation of a Real-Time Human Movement Classifier Using a Triaxial Accelerometer for Ambulatory Monitoring,” IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 10, NO. 1, JANUARY 2006

[2] Koichi Sagawa,Hikaru Inooka, Yutaka Satoh,“ Non-restricted measurement of walking distance,” IEEE Trans. January 30, 2009.

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Paper review(1) Abstract

In this way, the system distinguishes between periods of activity and rest.

Recognizes the postural orientation of the wearer, detects events such as walking and falls.

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Paper review(1) Abstract

12 tasks (283 tests)

Overall accuracy ： 90.8 %

Postural orientation ： 94.1 %

Walking ： 83.3 %

Fall ： 95.6 %

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Paper review(1) Methods

Form Michael R. Narayanan, Merry, Nigel H. Lovell, IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 10, NO. 1, JANUARY 2006

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Paper review(1) TA Unit

Triaxial Accelerometer (TA) ： Dimension ： 22 X 50 X 50 mm Weight ： 51 g Range ： ±10 g Noise ： 5.06 mg Bandwidth ： 100 Hz RAM ： 2 KB A/D ： 45 Hz

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Paper review(1) Flow Chart

TA signal

Median Filter

LPF

Computer SMA

SMA > th

AbnormalAcc. peak

Upright

Upright

Sitting Lying

Possible Fall

Upright Active Lying Active

Sitting Standing Inverted

DetermineLying Position

Front Back Right Left

n=3

LPF=0.25 HZ

RestActivity

YES

NO

YESNO

NO

NONO

YES

YES

YES

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TA signal

Median Filter

LPF

Computer SMA

SMA > th

AbnormalAcc. peak

Upright

Upright

Sitting Lying

Possible Fall





n=3

LPF=0.25 HZ

RestActivity

YES

NO

YESNO

NO

NONO

YES

YES

YES

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TA signal

Median Filter

LPF

Computer SMA

SMA > th

AbnormalAcc. peak

Upright

Upright

Sitting Lying

Possible Fall





n=3

LPF=0.25 HZ

RestActivity

YES

NO

YESNO

NO

NONO

YES

YES

YES

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TA signal

Median Filter

LPF

Computer SMA

SMA > th

AbnormalAcc. peak

Upright

Upright

Sitting Lying

Possible Fall





n=3

LPF=0.25 HZ

RestActivity

YES

NO

YESNO

NO

NONO

YES

YES

YES

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The first step is median filtering: n = 3

The second step is low pass filtering (LPF) ： Cut-off frequency at

0.25 Hz

Signal Magnitude Area (SMA) ：

SMA ：每秒所產生三軸運動量總和

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The z-axis and the gravitational vector g by the relation:

θ = cos-1(z).

Z-axis


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Classification of lying postures

X-axis

Y-axis


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signal magnitude vector (SVM) ：

SVM at a threshold of 1.8 g.

SVM:信號向量強度 (向量合 )

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Paper review(1)Trial Experiment Protocol


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Time (s) Time (s)

Walking (slow) Walking (fast)Form Michael R. Narayanan, Merry, Nigel H. Lovell, IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 10, NO. 1, JANUARY 2006

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Walking (slow) Walking (fast)Form Michael R. Narayanan, Merry, Nigel H. Lovell, IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 10, NO. 1, JANUARY 2006

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Paper review(2)Abstract

Walking distance is discussed.

A piezoelectric gyro.

The horizontal distance is obtained by integrating the horizontal acceleration twice every step.

Distance estimated ： 5.3 %

Average ： 0.0 %

Vertical distance ： 11.1 %.

Authorized licensed use limited to: Southern Taiwan University of Technology. Downloaded on January 30, 2009 at 02:45 from IEEE Xplore. Restrictions apply.

2009/11/2325

Paper review(2)Horizontal distance

deg/s：每秒角動量變化Authorized licensed use limited to: Southern Taiwan University of Technology. Downloaded on January 30, 2009 at 02:45 from IEEE Xplore. Restrictions apply.

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Paper review(2)Calculation method


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Paper review(2)Experiment


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Future Works

Use the Triaxial accelerometer to do it.

Find a good method to distinguishes the slow walking and lying.

To count of metabolic energy expenditure.

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References

[1] Dean M. Karantonis, Michael R. Narayanan, Merryn Mathie, Nigel H. Lovell, Branko G. Celler ,“Implementation of a Real-Time Human Movement Classifier Using a Triaxial Accelerometer for Ambulatory Monitoring,” IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 10, NO. 1, JANUARY 2006

[2] Koichi Sagawa,Hikaru Inooka, Yutaka Satoh“Non-restricted measurement of walking distance,” IEEE Trans. January 30, 2009.

using a triaxial accelerometer for movement monitoring presenter: chang-yu tsai adviser: cheng- jui...

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