Signal Processing - March 2016 - 40
Digitized Sensor
Acceleration Signal
200
150
100
50
0
0
1
2
3
4
5
6
Time (seconds)
7
8
9
10
Digitized Sensor
Acceleration Signal
fIguRe 4. A ten-second-long vibration sensor signal generated by a person walking.
200
150
100
50
0
0
0.2
0.4
0.6
1
1.2
0.8
Time (seconds)
(a)
1.4
1.6
1.8
2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Normalized Frequency (kHz)
(b)
0.8
0.9
1
x (jw)
8
6
4
2
0
fIguRe 5. (a) A two-second-long human fall record. (b) The Fourier transform magnitude.
The Fourier transform domain is divided into eight nonuniform bands, and subband energy values
are used as a feature set representing the time-domain vibration signal together with wavelet coefficients and Mel-frequency cepstral coefficiencts (MFCCs).
have a single vibration sensor unit installed on each floor of a
fallen items. Eight MFCCs, eight DFT coefficients, eight wavehouse; however, there are some challenges. This unit has to be
let coefficients, and eight CWT coefficients are extracted for
robust against variations on the type of the floor and the weight
each record. About 40% of falling and walking/running records
of the person as well as the distance
are used for training the SVM classifier.
between the sensor and the fall. The disAbout one-third of sitting, slammed door,
tance problem can be solved by installing
and fallen object records are also used for
AL systems may provide
two or more sensors, but this increases the
training. Remaining records are used as the
safety and autonomy
cost. To cover all possibilities, extensive
test data set. The data set is available to the
for elderly people while
studies have to be implemented. In addition,
public. Best recognition results are obtained
allowing them to live
the overall multisensor system described in
when complex wavelet transform based feaindependently, as well
[62] turns out to be a little bit too costly for
tures and modified mel-frequency cepstrum
as relieve the workload
a typical house and the network infrastruccoefficients are used. When combined with
ture. We hope that the Internet of Things
PIR sensors the multisensor AL system
of caregivers and
(IoT) will be widespread in the near future,
becomes very reliable. The AL system has
health providers.
which will make the entire system feasible.
the capability to place a phone call to a call
center whenever a fall is detected.
In [46], acoustic sensors are used instead of vibration senWearable accelerometer sensor signal processing
sors for fall detection. The acoustic sensor is placed like a
Even though several user-activated commercial devices are
stethoscope on the floor. In a practical system, it is desirable to
available for fall detection, they have limited benefits, especially
40
IEEE SIgnal ProcESSIng MagazInE
|
March 2016
|
Table of Contents for the Digital Edition of Signal Processing - March 2016
Signal Processing - March 2016 - Cover1
Signal Processing - March 2016 - Cover2
Signal Processing - March 2016 - 1
Signal Processing - March 2016 - 2
Signal Processing - March 2016 - 3
Signal Processing - March 2016 - 4
Signal Processing - March 2016 - 5
Signal Processing - March 2016 - 6
Signal Processing - March 2016 - 7
Signal Processing - March 2016 - 8
Signal Processing - March 2016 - 9
Signal Processing - March 2016 - 10
Signal Processing - March 2016 - 11
Signal Processing - March 2016 - 12
Signal Processing - March 2016 - 13
Signal Processing - March 2016 - 14
Signal Processing - March 2016 - 15
Signal Processing - March 2016 - 16
Signal Processing - March 2016 - 17
Signal Processing - March 2016 - 18
Signal Processing - March 2016 - 19
Signal Processing - March 2016 - 20
Signal Processing - March 2016 - 21
Signal Processing - March 2016 - 22
Signal Processing - March 2016 - 23
Signal Processing - March 2016 - 24
Signal Processing - March 2016 - 25
Signal Processing - March 2016 - 26
Signal Processing - March 2016 - 27
Signal Processing - March 2016 - 28
Signal Processing - March 2016 - 29
Signal Processing - March 2016 - 30
Signal Processing - March 2016 - 31
Signal Processing - March 2016 - 32
Signal Processing - March 2016 - 33
Signal Processing - March 2016 - 34
Signal Processing - March 2016 - 35
Signal Processing - March 2016 - 36
Signal Processing - March 2016 - 37
Signal Processing - March 2016 - 38
Signal Processing - March 2016 - 39
Signal Processing - March 2016 - 40
Signal Processing - March 2016 - 41
Signal Processing - March 2016 - 42
Signal Processing - March 2016 - 43
Signal Processing - March 2016 - 44
Signal Processing - March 2016 - 45
Signal Processing - March 2016 - 46
Signal Processing - March 2016 - 47
Signal Processing - March 2016 - 48
Signal Processing - March 2016 - 49
Signal Processing - March 2016 - 50
Signal Processing - March 2016 - 51
Signal Processing - March 2016 - 52
Signal Processing - March 2016 - 53
Signal Processing - March 2016 - 54
Signal Processing - March 2016 - 55
Signal Processing - March 2016 - 56
Signal Processing - March 2016 - 57
Signal Processing - March 2016 - 58
Signal Processing - March 2016 - 59
Signal Processing - March 2016 - 60
Signal Processing - March 2016 - 61
Signal Processing - March 2016 - 62
Signal Processing - March 2016 - 63
Signal Processing - March 2016 - 64
Signal Processing - March 2016 - 65
Signal Processing - March 2016 - 66
Signal Processing - March 2016 - 67
Signal Processing - March 2016 - 68
Signal Processing - March 2016 - 69
Signal Processing - March 2016 - 70
Signal Processing - March 2016 - 71
Signal Processing - March 2016 - 72
Signal Processing - March 2016 - 73
Signal Processing - March 2016 - 74
Signal Processing - March 2016 - 75
Signal Processing - March 2016 - 76
Signal Processing - March 2016 - 77
Signal Processing - March 2016 - 78
Signal Processing - March 2016 - 79
Signal Processing - March 2016 - 80
Signal Processing - March 2016 - 81
Signal Processing - March 2016 - 82
Signal Processing - March 2016 - 83
Signal Processing - March 2016 - 84
Signal Processing - March 2016 - 85
Signal Processing - March 2016 - 86
Signal Processing - March 2016 - 87
Signal Processing - March 2016 - 88
Signal Processing - March 2016 - 89
Signal Processing - March 2016 - 90
Signal Processing - March 2016 - 91
Signal Processing - March 2016 - 92
Signal Processing - March 2016 - 93
Signal Processing - March 2016 - 94
Signal Processing - March 2016 - 95
Signal Processing - March 2016 - 96
Signal Processing - March 2016 - 97
Signal Processing - March 2016 - 98
Signal Processing - March 2016 - 99
Signal Processing - March 2016 - 100
Signal Processing - March 2016 - 101
Signal Processing - March 2016 - 102
Signal Processing - March 2016 - 103
Signal Processing - March 2016 - 104
Signal Processing - March 2016 - 105
Signal Processing - March 2016 - 106
Signal Processing - March 2016 - 107
Signal Processing - March 2016 - 108
Signal Processing - March 2016 - 109
Signal Processing - March 2016 - 110
Signal Processing - March 2016 - 111
Signal Processing - March 2016 - 112
Signal Processing - March 2016 - 113
Signal Processing - March 2016 - 114
Signal Processing - March 2016 - 115
Signal Processing - March 2016 - 116
Signal Processing - March 2016 - 117
Signal Processing - March 2016 - 118
Signal Processing - March 2016 - 119
Signal Processing - March 2016 - 120
Signal Processing - March 2016 - 121
Signal Processing - March 2016 - 122
Signal Processing - March 2016 - 123
Signal Processing - March 2016 - 124
Signal Processing - March 2016 - 125
Signal Processing - March 2016 - 126
Signal Processing - March 2016 - 127
Signal Processing - March 2016 - 128
Signal Processing - March 2016 - Cover3
Signal Processing - March 2016 - Cover4
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