Fault detection method and system

1. A method of detecting faults in a member, said member having a first and second face opposite each other and communicating fluidically in the presence of at least one fault; the method comprising the steps of:

generating a first sound signal with a transmitter, so that said first sound signal interacts with at least one portion of the first face of the member;

arranging a receiver, configured to receive a second sound signal, close to a respective portion of said second face of the member corresponding to said portion of said first face, said second sound signal being the outcome of said first sound signal interacting with said member;

moving said receiver, close to the second face of the member;

generating a detection signal with the receiver, as a function of the received said second sound signal;

calculating, at a number of instants (ti˜t N ) in which said receiver is moved, respective detection values (A τ , B τ , N τ ) of a quantity associated with the energy of said detection signal; and

in the event of said at least one fault in said member:

locating the fault on the basis of said detection values and of the positions assumed by said receiver at the respective instants,

calculating a discrimination threshold, adaptively varying between a peak value (IMX) and a noise value (IMN) of said detection values as a function of said peak value and noise value the peak value being the highest value among said detection values and the noise value being the lowest value among said detection values, and

acquiring a spectrogram of said detection signal for a number of frequencies (fi-f M ) and said number of instants (ti˜t N ), so as to associate a respective amplitude value (Ai-A M ; Bi-B M , Xi-X M ; Ni-N M ) with each pair defined by a frequency in said number of frequencies, and an instant in said number of instants; and, for each of the instants in said number of instants, summing the amplitude values associated with the same instant, to obtain said detection values (A τ , B T , N T ) of said quantity associated with the energy of said detection signal.

2. The method as claimed in claim 1 , wherein said first sound signal is an inaudible-frequency signal, and said step of generating a detection signal comprises the step of converting the received said second sound signal to an audible-frequency signal.

3. The method as claimed in claim 1 , wherein said locating step comprises:

determining the presence of said at least one fault when at least one of said detection values (A τ , B T , N T ) exceeds said discrimination threshold; determining the position assumed by said receiver at the instant associated with said at least one of said detection values; and

determining the location of said at least one fault as a function of said position assumed by said receiver.

4. The method as claimed in claim 3 , wherein said step of determining the presence of said at least one fault comprises determining said presence when a predetermined number of consecutive detection values among said detection values exceed said discrimination threshold.

5. The method as claimed in claim 3 , wherein the step of defining a discrimination threshold comprises the steps of:

acquiring the peak value (IMX);

acquiring the noise value (IMN);

calculating a percentage value of said peak value (IMX);

multiplying said noise value (IMN) by a proportionality factor;

acquiring the maximum value (ITU) of said peak value and said noise value;

multiplying said maximum value (ITU) of said peak value and said noise value by a compensation factor; and calculating a fraction of said maximum value (ITU).

6. The method as claimed in claim 3 , wherein the step of defining a discrimination threshold comprises the steps of:

acquiring the peak value (IMX);

acquiring the noise value (IMN);

calculating a percentage value of said peak value (IMX);

multiplying said noise value (IMN) by a proportionality factor;

acquiring the minimum value (ITL) of said peak value and said noise value; and

multiplying said minimum value (ITL) of said peak value and said noise value by a compensation factor.

7. A system for detecting faults in a member, said member having a first and a second face opposite each other and communicating fluidically in the presence of at least one fault; said system comprising:

a transmitter positioned facing a portion of the first face of the member, and configured to generate an inaudible-frequency sound signal;

a receiver positioned movably facing a portion of the second face of the member, and configured to receive the sound signal generated by the transmitter and convert it to an audible-frequency detection signal; and

processing means for:

receiving the detection signal;

calculating, at a number of instants (t 1 -t N ) in which the receiver is moved, respective detection values (A τ , B τ , N τ ) of a quantity associated with the energy of said detection signal;

in the event of said at least one fault in said member, locating the fault on the basis of said detection values and of the positions assumed by said receiver at respective instants;

calculating, as a function of a peak value (IMX) and a noise value (IMN) of said detection values, a discrimination threshold adaptively varying between the peak value and the noise value, the peak value being the highest value among said detection values and the noise value being the lowest value among said detection values; and

acquiring a spectrogram of said detection signal for a number of frequencies (fi-f M ) and said number of instants (ti˜t N ), so as to associate a amplitude value (Ai-A M ; Bi-B M , Xi ˜ X M ; Ni ˜ N M ) with each pair defined by a frequency in said number of frequencies and an instant in said number of instants; and, for all the instants in said number of instants, to sum the amplitude values associated with the same instant, to obtain said detection values (A τ , B τ N τ ) of said quantity associated with the energy of said detection signal.

8. The system as claimed in claim 7 , wherein said first sound signal is an inaudible-frequency signal, and said processing means are for converting the received said second sound signal to an audible-frequency signal.

9. The system as claimed in claim 7 , wherein said processing means are for:

determining the presence of said at least one fault when at least one of said detection values (A τ , B T , N T ) exceeds said discrimination threshold; determine the position assumed by said receiver at the instant associated with said at least one of said detection values; and

determining the location of said at least one fault as a function of said position assumed by said receiver.

10. The system as claimed in claim 9 , wherein said processing means are for determining said presence of said at least one fault when a predetermined number of consecutive detection values among said detection values exceed said discrimination threshold.

11. The system as claimed in claim 9 , wherein said processing means are for:

acquiring the peak value (IMX);

acquiring the noise value (IMN);

calculating a percentage value of said peak value (IMX);

multiplying said noise value (IMN) by a proportionality factor;

acquiring the maximum value (ITU) of said peak value and said noise value;

multiplying said maximum value (ITU) of said peak value and said noise value by a compensation factor; and calculating a fraction of said maximum value (ITU).

12. The system as claimed in claim 9 , wherein said processing means are for:

acquiring the peak value (IMX);

acquiring the noise value (IMN);

calculating a percentage value of said peak value (IMX);

multiplying said noise value (IMN) by a proportionality factor;

acquiring the minimum value (ITL) of said peak value and said noise value; and

multiplying said minimum value (ITL) of said peak value and said noise value by a compensation factor.

13. A system for detecting faults in a member, said member having a first and a second face opposite each other and communicating fluidically in the presence of at least one fault; said system comprising:

a transmitter positioned facing a portion of the first face of the member, and configured for generating an inaudible-frequency sound signal;

a receiver positioned movably facing a portion of the second face of the member, and configured for receiving the sound signal generated by the transmitter and convert it to an audible-frequency detection signal; and

a processor configured to:

receive the detection signal;

calculate, at a number of instants (t 1 -t N ) in which the receiver is moved, respective detection values (A τ , B τ , N τ ) of a quantity associated with the energy of said detection signal;

in the event of said at least one fault in said member, locate the fault on the basis of said detection values and of the positions assumed by said receiver at respective instants;

calculate, as a function of a peak value (IMX) and a noise value (IMN) of said detection values, a discrimination threshold adaptively varying between the peak value and the noise value the peak value being the highest value among said detection values and the noise value being the lowest value among said detection values; and

acquire a spectrogram of said detection signal for a number of frequencies (fi-f M ) and said number of instants (ti˜t N ), so as to associate a amplitude value (Ai-A M ; Bi-B M , Xi ˜ X M ; Ni ˜ N M ) with each pair defined by a frequency in said number of frequencies and an instant in said number of instants; and, for all the instants in said number of instants, to sum the amplitude values associated with the same instant, to obtain said detection values (A τ , B τ N τ ) of said quantity associated with the energy of said detection signal.

14. The system as claimed in claim 13 , wherein said first sound signal is an inaudible-frequency signal, and said processor is configured to convert the received said second sound signal to an audible-frequency signal.