Biomedical Engineering Reference
In-Depth Information
1
1
0
0
II
0
500
1000
1500
2000
0
500
1000
1500
2000
-1
-1
I
II
I
-2
-2
-3
-3
-4
-4
Time (ms)
(a) Measured voltage and fitted curve
at
F
o
= 150 N and
t
o
= 250 ms
Time (ms)
(b) Measured voltage and fitted curve
at
F
o
= 150 N and
t
o
= 500 ms
1
1
0
0
0
500
1000
1500
2000
0
500
1000
1500
2000
II
II
-1
-1
I
I
-2
-2
-3
-3
-4
-4
Time (ms)
(c) Measured voltage and fitted curve
at
F
o
= 150 N and
t
o
= 1000 ms
Time (ms)
(d) Measured voltage and fitted curve
at
F
o
= 100 N and
t
o
= 250 ms
1
II
0
0
500
1000
1500
2000
I
-1
-2
-3
-4
Time (ms)
(e) Measured voltage and fitted curve
at
F
o
= 50 N and
t
o
= 250 ms
FIGURE 9.12
Fitting functions with different
F
o
and
t
o
for sample no. 1 (I: fitting results; II: measured results).
relaxation) during load holding. Equation (9.1) represents the fitting function
for the measured piezovoltage
V
(
t
):
β
t
d
−
()
()
τ
(9.1)
Vt
=
KF te
where
t
is time
F
(
t
) is the load function
K
is a proportional coefficient between load
F
(
t
) and piezovoltage