Method for determining the location of impacts by acoustic imaging
First Claim
Patent Images
1. A computer-implemented method that is tied to a particular tangible physical object that includes a surface having N acoustic sensors, where N is at least 3, and M determined areas, said computer-implemented method being for the determination of a location of an impact on said surface, said impact generating an acoustic signal, wherein each acoustic sensor receives said acoustic signal and transmits a sensed signal to a processing unit, said method comprising(a) computing P intercorrelation products Pij(ω
- )=Si(ω
)·
S*j(ω
), where Si(ω
) is a Fourier transform of a sensed signal si(t) sensed by a sensor i of the N acoustic sensors;
Sj(ω
) is a Fourier transform of a sensed signal sj(t) sensed by a sensor j of the N acoustic sensors; and
“
*”
is the complex conjugate operator, whereby the Fourier transform of the sensed signals is given respectively by Si(ω
)=Ci(ω
)·
exp(−
j×
di)·
E(ω
), and Sj(ω
)=Cj(ω
)·
exp(−
j×
dj)·
E(ω
), where Cj(ω
) and Cj(ω
) are respective frequency complex responses of the sensors i and j, x=ω
/C with C being an acoustic propagation velocity, di and dj are respective distances between the impact location and the sensors i and j, and E(ω
) is the Fourier transform of the impact waveform such that Pij(ω
) does not depend crucially on time origin and impact waveform;
(b) calculating P inverse Fourier transforms p′
ij(u) of said Pij(ω
);
(c) computing, for each area k of the M determined areas, Pk(u)=Σ
p′
ij(u−
τ
ijk), where in a non-dispersive surface, u is a time and tijk is a stored predetermined delay value based on a difference between the respective locations of the area k and the sensors i and j, and in a dispersive surface, u is a distance and tijk is a length depending on a distance between the area k and the sensor i and the distance between the area k and the sensor j; and
(d) calculating a characterizing value f(Pk(u)) of each Pk(u), and identifying, as the determined location of the impact, an area k0 corresponding to an area k having a greatest characterizing value such that the function Pk0(u) is closest to being an impulse.
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Abstract
A method for determining the location of an impact on a surface (1) comprising N acoustic sensors (2a, 2b, 2c), transmitting a sensed signal si(t) to a processing unit (4) comprises the following steps (a) computing P intercorrelation products (b) calculating P inverse Fourier transforms p′ij (u) (c) computing for each area k, Pk(u)=ΣP′ij (u−τijk); d) finding k0, where a characterizing value of Pk0 (u) is greater than a given threshold value.
66 Citations
18 Claims
-
1. A computer-implemented method that is tied to a particular tangible physical object that includes a surface having N acoustic sensors, where N is at least 3, and M determined areas, said computer-implemented method being for the determination of a location of an impact on said surface, said impact generating an acoustic signal, wherein each acoustic sensor receives said acoustic signal and transmits a sensed signal to a processing unit, said method comprising
(a) computing P intercorrelation products Pij(ω - )=Si(ω
)·
S*j(ω
), where Si(ω
) is a Fourier transform of a sensed signal si(t) sensed by a sensor i of the N acoustic sensors;Sj(ω
) is a Fourier transform of a sensed signal sj(t) sensed by a sensor j of the N acoustic sensors; and
“
*”
is the complex conjugate operator, whereby the Fourier transform of the sensed signals is given respectively by Si(ω
)=Ci(ω
)·
exp(−
j×
di)·
E(ω
), and Sj(ω
)=Cj(ω
)·
exp(−
j×
dj)·
E(ω
), where Cj(ω
) and Cj(ω
) are respective frequency complex responses of the sensors i and j, x=ω
/C with C being an acoustic propagation velocity, di and dj are respective distances between the impact location and the sensors i and j, and E(ω
) is the Fourier transform of the impact waveform such that Pij(ω
) does not depend crucially on time origin and impact waveform;(b) calculating P inverse Fourier transforms p′
ij(u) of said Pij(ω
);(c) computing, for each area k of the M determined areas, Pk(u)=Σ
p′
ij(u−
τ
ijk), where in a non-dispersive surface, u is a time and tijk is a stored predetermined delay value based on a difference between the respective locations of the area k and the sensors i and j, and in a dispersive surface, u is a distance and tijk is a length depending on a distance between the area k and the sensor i and the distance between the area k and the sensor j; and(d) calculating a characterizing value f(Pk(u)) of each Pk(u), and identifying, as the determined location of the impact, an area k0 corresponding to an area k having a greatest characterizing value such that the function Pk0(u) is closest to being an impulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17)
- )=Si(ω
-
16. A device for determining the location of an impact on a surface of an object, said surface comprising M determined areas and said impact generating an acoustic signal, said device comprising:
- a processing unit; and
N acoustic sensors adapted to be borne by said surface, where N is at least 3, each sensor i receiving said acoustic signal and transmitting a sensed signal si(t) to the processing unit, wherein said processing unit comprises;
means for computing P intercorrelation products Pij(ω
)=Si(ω
)·
S*j(ω
), where Si(ω
) is a Fourier transform of a sensed signal si(t) sensed by a sensor i of the N acoustic sensors;
Sj(ω
) is a Fourier transform of a sensed signal sj(t) sensed by a sensor j of the N acoustic sensors; and
“
*”
is the complex conjugate operator, whereby the Fourier transform of the sensed signals is given respectively by St(ω
)=Ci(ω
)·
exp(−
j×
di)·
E(ω
), and Sj(ω
)=Cj(ω
)·
exp(−
j×
dj)·
E(ω
), where Ci(ω
) and Cj(ω
) are respective frequency complex responses of the sensors i and j, x=ω
/C with C being an acoustic propagation velocity, di and dj are respective distances between the impact location and the sensors i and j, and E(ω
) is the Fourier transform of the impact waveform such that Pij(ω
) does not depend crucially on time origin and impact waveform;
means for calculating P inverse Fourier transforms p′
ij(u) of said p′
ij(ω
);
means for computing, for each area k of the M determined areas, Pk(u)=Σ
p′
ij(u−
τ
ijk), where in a non-dispersive surface, u is a time and tijk is a stored predetermined delay value based on a difference between the respective locations of the area k and the sensors i and j, and in a dispersive surface, u is a distance and tijk is a length depending on a distance between the area k and the sensor i and the distance between the area k and the sensor j; and
means for calculating a characterizing value f(Pk(u)) of each Pk(u), and identifying, as the determined location of the impact, an area k0 corresponding to an area k having a greatest characterizing value such that the function Pk0(u) is closest to being an impulse. - View Dependent Claims (18)
- a processing unit; and
Specification
-
- Resources
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Current AssigneeElo Touch Solutions, Inc.
-
Original AssigneeElo Touch Solutions, Inc.
-
InventorsIng, Ros Kiri
-
Primary Examiner(s)MANDEVILLE, JASON M
-
Application NumberUS11/911,398Publication NumberTime in Patent Office3,282 DaysField of Search345/173, 345/177, 367/21, 367/38, 367/39, 367/41, 367/42, 367/118US Class Current345/177CPC Class CodesG01N 29/069 Defect imaging, localisatio...G01N 29/14 using acoustic emission tec...G01N 29/4472 Mathematical theories or si...G01N 29/46 by spectral analysis, e.g. ...G01N 29/50 using auto-correlation tech...G06F 3/043 using propagating acoustic ...
