Patent ID: 8692810

Claim:
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 P ij (ω)=S i (ω)·S* j (ω), where S i (ω) is a Fourier transform of a sensed signal s i (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 S i (ω)=C i (ω)·exp(−j×d i )·E(ω), and S j (ω)=C j (ω)·exp(−j×d j )·E(ω), where C j (ω) and C j (ω) are respective frequency complex responses of the sensors i and j, x=ω/C with C being an acoustic propagation velocity, d i and d j 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 P ij(ω) does not depend crucially on time origin and impact waveform; (b) calculating P inverse Fourier transforms p′ ij (u) of said P ij (ω); (c) computing, for each area k of the M determined areas, P k (u)=Σp′ ij (u−τ ijk ), where in a non-dispersive surface, u is a time and t ijk 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 t ijk 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(P k (u)) of each P k (u), and identifying, as the determined location of the impact, an area k 0 corresponding to an area k having a greatest characterizing value such that the function P k0 (u) is closest to being an impulse.