Active vibration or noise suppression system
An active vibration or noise suppression system is provided that achieves fast convergence of vibration or noise. A sine wave control signal y (n) is constituted by frequency of a vibration or noise source, and an amplitude filter coefficient a (n) and a phase filter coefficient φ (n) as an adaptive filter coefficient. The sine wave control signal y (n) is expressed by a sine wave having an amplitude component and a phase component, and each of an amplitude update term Δa (n+1) and a phase update term Δφ (n+1) includes a sine wave or cosine wave term having an amplitude component and a phase component. The phase component of the sine wave control signal y (n) is multiplied by a coefficient other than 1, or the phase component of the sine wave or cosine wave term of each of the amplitude update term Δa (n+1) and the phase update term Δφ (n+1) is multiplied by a coefficient other than 1.
1. An active vibration or noise suppression system is applied to a vehicle for actively suppressing vibration or noise at an evaluation point by outputting control vibration or control sound, comprising:
an active vibration or noise suppression circuit that generates a sine wave control signal y (n) constituted by frequency of a vibration or noise source, and an amplitude filter coefficient a (n) and a phase filter coefficient φ (n) as an adaptive filter coefficient;
outputs the control vibration or control sound corresponding to the sine wave control signal y (n) ;
detects, at the evaluation point, a residual error signal e (n) generated by interference between vibration or noise caused by the vibration or noise source and the control vibration or control sound;
calculates an amplitude update term Δa (n+1) to be added to or subtracted from a last updated value of the amplitude filter coefficient a (n) for update, so as to reduce the residual error signal e (n) ; and
calculates a phase update term Δφ (n+1) to be added to or subtracted from a last updated value of the phase filter coefficient φ (n) for update, so as to reduce the residual error signal e (n) ,
the sine wave control signal y (n) is expressed by a sine wave having an amplitude component and a phase component,
each of the amplitude update term Δa (n+1) and the phase update term Δφ (n+1) contains a sine wave or cosine wave term having an amplitude component and a phase component, and
the phase component of the sine wave control signal y (n) is expressed by multiplying a coefficient other than 1 by the phase filter coefficient φ (n) , or the phase component of the sine wave or cosine wave term of each of the amplitude update term Δa (n+1) and the phase update term Δφ (n+1) is expressed by multiplying a coefficient other than 1 by the phase filter coefficient φ (n) ,
wherein the active vibration or noise suppression circuit improves convergence,
wherein the phase component of the sine wave control signal y (n) is expressed by multiplying a value greater than 1 by the phase filter coefficient φ (n) , and
wherein the sine wave control signal y (n) is expressed by Equation (1);
[Equation 1]
y (n) =a (n) ·sin(ω· t (n) +q·φ (n) ) (1)
wherein:
y (n) : sine wave control signal
a (n) : amplitude filter coefficient
φ (n) : phase filter coefficient
ω: angular frequency
q: phase multiplier coefficient (q >1)
t (n) : sampling time
(n): the number of samples (time step).
2. The active vibration or noise suppression system according to claim 1 , wherein:
the sine wave or cosine wave term of the amplitude update term Δa (n+1) is a term in Expression (2); and
the sine wave or cosine wave term of the phase update term Δφ (n+1) is a term in Expression (3);
[
Expression
2
]
a
1
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
ϕ
1
)
(
2
)
wherein:
e (n) : residual error signal
a 1 : amplitude coefficient
φ 1 : phase coefficient
m: stability coefficient (m ≧1)
[
Expression
3
]
a
2
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
ϕ
2
)
(
3
)
wherein:
a 2 : amplitude coefficient
φ 2 : phase coefficient.
3. The active vibration or noise suppression system according to claim 2 ,
wherein the amplitude coefficient a 1 and the phase coefficient φ 1 in Expression (2) and the amplitude coefficient a 2 and the phase coefficient φ 2 in Expression (3) are coefficients which are independent of a transfer function between the control signal generator and the evaluation point.
4. The active noise vibration or noise suppression system according to claim 3 , wherein:
Expression (2) is replaced by Expression (4); and
Expression (3) is replaced by Expression (5);
[
Expression
4
]
μ
a
2
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
)
(
4
)
wherein μ a2 : step size parameter
[
Expression
5
]
μ
ϕ
2
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
)
(
5
)
wherein μ φ2 : step size parameter.
5. The active vibration or noise suppression system according to claim 2 , wherein:
the active vibration or noise suppression system further comprises an estimated transfer function storage for storing an estimate value of a transfer function between the control signal generator and the evaluation point beforehand; and
at least one of the amplitude coefficient a 1 and the phase coefficient φ 1 in Expression (2), and at least one of the amplitude coefficient a 2 and the phase coefficient φ 2 in Expression (3) are coefficients obtained based on the estimate value of the transfer function.
6. The active vibration or noise suppression system according to claim 5 , wherein:
Expression (2) is replaced by Expression (6); and
Expression (3) is replaced by Expression (7);
[
Expression
6
]
μ
a
1
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
Φ
^
p
)
A
^
(
6
)
wherein:
μ a1 : step size parameter
Â: amplitude component of the estimate value of the transfer function
{circumflex over (φ)}phase component of the estimate value of the transfer function
p: coefficient
[
Expression
7
]
μ
ϕ
1
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
Φ
^
p
)
(
7
)
wherein μ φ1 : step size parameter.
7. The active vibration or noise suppression system according to claim 2 , wherein:
the stability coefficient m is set to a value greater than 1; and
the phase multiplier coefficient q is set to a value greater than the stability coefficient m.
8. An active vibration or noise suppression system is applied to a vehicle for actively suppressing vibration or noise at an evaluation point by outputting control vibration or control sound, comprising:
an active vibration or noise suppression circuit that
generates a sine wave control signal y (n) constituted by frequency of a vibration or noise source, and an amplitude filter coefficient a (n) and a phase filter coefficient 100 (n) as an adaptive filter coefficient;
outputs the control vibration or control sound corresponding to the sine wave control signal y (n) ;
detects, at the evaluation point, a residual error signal e (n) generated by interference between vibration or noise caused by the vibration or noise source and the control vibration or control sound;
calculates an amplitude update term Δa (n) to be added to or subtracted from a last updated value of the amplitude filter coefficient a (n) for update, so as to reduce the residual error signal e (n) ; and
calculates a phase update term Δφ (n) to be added to or subtracted from a last updated value of the phase filter coefficient φ (n) for update, so as to reduce the residual error signal e (n) ,
the sine wave control signal y (n) is expressed by a sine wave having an amplitude component and a phase component,
each of the amplitude update term Δa (n+1) and the phase update term Δφ (n+1) contains a sine wave or cosine wave term having an amplitude component and a phase component, and
the phase component of the sine wave control signal y (n) is expressed by multiplying a coefficient other than 1 by the phase filter coefficient φ (n) , or the phase component of the sine wave or cosine wave term of each of the amplitude update term φa (n+1) and the phase update term φΔ (n+1) is expressed by multiplying a coefficient other than 1 by the phase filter coefficient φ (n) ,
wherein the active vibration or noise suppression circuit improves convergence,
wherein when the sine wave control signal y (n) is expressed by Equation (8),
the sine wave or cosine wave term of the amplitude update term Δa (n+1) contains a sine wave term in Expression (9); and
the sine wave or cosine wave term of the phase update term Δa (n+1) contains a cosine wave term in Expression (10);
[Equation 8]
y (n) =a (n) ·sin(ω· t (n) =φ (n) ) (8)
wherein:
y (n) sine wave control signal
a (n) ): amplitude filter coefficient
φ (n) : phase filter coefficient
ω: angular frequency
t (n) : sampling time
(n): the number of samples (time step)
[
Expression
9
]
a
1
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
ϕ
1
)
(
9
)
wherein:
e (n) :residual error signal
a 1 : amplitude coefficient
φ 1 : phase coefficient
m: stability coefficient (m >1)
[
Expression
10
]
a
2
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
ϕ
2
)
(
10
)
wherein:
a 2 : amplitude coefficient
φ 2 : phase coefficient.
9. The active vibration or noise suppression system according to claim 8 ,
wherein the amplitude coefficient a 1 and the phase coefficient φ 1 in Expression (9) and the amplitude coefficient a 2 and the phase coefficient φ 2 in Expression (10) are coefficients which are independent of a transfer function between the control signal generator and the evaluation point.
10. The active vibration or noise suppression system according to claim 9 , wherein:
Expression (9) is replaced by Expression (11); and
Expression (10) is replaced by Expression (12);
[
Expression
11
]
μ
a
2
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
)
(
11
)
wherein μ a2 : step size parameter
[
Expression
12
]
μ
ϕ
2
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
)
(
12
)
wherein μ φ2 : step size parameter.
11. The active vibration or noise suppression system according to claim 8 , wherein:
the active vibration or noise suppression system further comprises an estimated transfer function storage for storing an estimate value of a transfer function between the control signal generator and the evaluation point beforehand, and
at least one of the amplitude coefficient a 1 and the phase coefficient φ 1 in Expression (9), and at least one of the amplitude coefficient a 2 and the phase coefficient φ 2 in Expression (10) are coefficients obtained based on the estimate value of the transfer function.
12. The active vibration or noise suppression system according to claim 11 , wherein:
Expression (9) is replaced by Expression (13), and
Expression (10) is replaced by Expression (14);
[
Expression
13
]
μ
a
1
·
e
(
n
)
·
sin
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
Φ
^
p
)
A
^
(
13
)
wherein:
μ a1 : step size parameter
Â: amplitude component of the estimate value of the transfer function
{circumflex over (φ)}phase component of the estimate value of the transfer function
p: coefficient
[
Expression
14
]
μ
ϕ
1
·
e
(
n
)
·
cos
(
ω
·
t
(
n
)
+
ϕ
(
n
)
m
+
Φ
^
p
)
(
14
)
wherein μ φ1 : step size parameter.
13. The active vibration or noise suppression system according to claim 1 ,
wherein an initial value φ (0) of the phase filter coefficient is set based on a value φ (last) of the phase filter coefficient at a time of last convergence.
14. The active vibration or noise suppression system according to claim 13 ,
wherein the initial value φ (0) of the phase filter coefficient is the value φ (last) of the phase filter coefficient at the time of last convergence.
15. The active vibration or noise suppression system according to claim 13 ,
wherein the initial value φ (0) of the phase filter coefficient is set based on the value φ (last) of the phase filter coefficient at the time of last convergence, frequency f at the time of last convergence, and frequency f at a present time.
16. The active vibration or noise suppression system according to claim 13 ,
wherein an initial value a (0) of the amplitude filter coefficient is set based on frequency f at a present time.
17. The active vibration or noise suppression system according to claim 13 ,
wherein a step size parameter of the amplitude update term ωa (n+1) is set based on a value a (last) of the amplitude filter coefficient at the time of last convergence.
18. The active vibration or noise suppression system according to claim 17 , wherein:
the active vibration or noise suppression system is applied to a vehicle having an engine; and
the step size parameter of the amplitude update term ωa (n+1) is set to a value which is proportional to a value obtained by dividing the value a (last) of the amplitude filter coefficient at the time of last convergence by a value trq (last) of a driving torque variation amount of the engine at the time of last convergence.
19. The active vibration or noise suppression system according to claim 1 ,
wherein an initial value φ (0) of the phase filter coefficient is set within a range which satisfies Inequality (15);
[
Math
.
15
]
4
k
+
1
2
π
<
ϕ
(
0
)
<
4
k
+
3
2
π
(
15
)
wherein: k: integer.
20. The active vibration or noise suppression system according to claim 1 , wherein the amplitude filter coefficient is a positive number.
21. An active vibration or noise suppression system for actively suppressing vibration or noise at an evaluation point by outputting control vibration or control sound, comprising:
an active vibration or noise suppression circuit that generates a sine wave control signal y (n) constituted by frequency of a vibration or noise source, and an amplitude filter coefficient a (n) and a phase filter coefficient φ (n) as an adaptive filter coefficient;
outputs the control signal or control sound corresponding to the sine wave control signal y (n) ;
detects a residual error signal e (n) generated by interference between vibration or noise caused by the vibration or noise source and the control vibration or control sound at the evaluation point;
calculates an amplitude update term Δa (n+1) to be added to or subtracted from a last updated value of the amplitude filter coefficient a (n) for update, so as to reduce the residual error signal e (n) ; and
calculates a phase update term Δφ (n+1) to be added to or subtracted from a last updated value of the phase filter coefficient φ (n) for update, so as to reduce the residual error signal e (n) ; and
an initial value φ (0) of the phase filter coefficient is set based on a value φ (last) of the phase filter coefficient at a time of last convergence,
wherein the active vibration or noise suppression system is applied to a vehicle having an engine,
wherein the active vibration or noise suppression circuit improves convergence, and
wherein a step size parameter of the amplitude update term Δa (n+1) is set to a value which is proportional to a value obtained by dividing the value a (last) of the amplitude filter coefficient at the time of last convergence by a value trq (last) of a driving torque variation amount of the engine at the time of last convergence.