SYSTEM AND METHOD FOR DETECTING DEFECTS IN ELONGATED STRUCTURES

Abstract

The present invention relates to a system and method for detecting defects in an elongated structure acting as an ultrasonic waveguide, in particular a railway track-type structure. The elongated structure is instrumented with a plurality of transducers capable of acquiring measurement signals of characteristic quantities of guided ultrasonic waves propagating in the structure. Each transducer is coupled to an electronic device installed along the structure and configured to process measurement signals received from at least one transducer. All the electronic devices are synchronized to the same clock. Figure for the abstract: Fig. 1

Claims

Demands

1. Method for detecting defects in an elongated structure acting as an ultrasonic waveguide, said elongated structure being equipped with a plurality of transducers capable of acquiring signals for measuring characteristic quantities of ultrasonic waves guided particles propagating within said elongated structure, each transducer being coupled to an electronic device installed along said structure, this electronic device being configured to process measurement signals received from at least one transducer, the set of Since electronic devices are synchronized to the same clock, the process being implemented by computer and comprising the steps consisting of: - (602, 604) to be carried out between a transmitting transducer and a transducer receiver, at least one operation of transmitting and receiving a wave guided ultrasound in the elongated structure, said ultrasound wave guided corresponding to a modulated signal where the signal is a Y(-t) signal obtained by time reversal of an acquired calibration signal Y(t) between the receiving transducer and the transmitting transducer, and where the mo- modulation is a predefined initial modulation code composed of a bit sequence with 0 and 1; - (608) perform a mathematical correlation between the initial code of predefined modulation and the signal 's' received by the receiving transducer, or between the initial predefined modulation code and the averaged signal s””” signals received by the receiving transducer; - (610) compare the correlation result to a predefined threshold; and - (612) depending on the result of the comparison, determine whether or not there is a defect in the elongated structure between the transmitting transducer and the transducer receiver.

2. A method according to claim 1, comprising before the emission step and reception, a preliminary step (601) of calibration of each of the dis- positive electronics associated with the transmitting transducer and the transducer receiver, the calibration consisting of transmitting from said The transducer receives a signal and receives a calibration signal. Y / (t) by said emitting transducer.

3. A method according to claim 1 comprising before the emission step and reception, a preliminary step (601) of calibration of each of the dis- positive electronics associated with the transmitting transducer and the transducer receiver, the calibration consisting of transmitting from said transducer emits a signal, to receive a calibration signal Y(t) at the level of said receiving transducer, and to communicate the signal of calibration audit transducer transmitter to store it before re- time twist.

4. A method according to claim 2 or 3 wherein the preliminary step (601) further includes a step of defining an initial code of calibration signal modulation, composed of a sequence of bits to - lethal.

5. A method according to any one of claims 1 to 4 wherein the The initial modulation code also includes a bit sequence of error correction chosen either as a single parity bit, or as a more complex code, such as a Hamming code or a Golay code.

6. A method according to any one of the preceding claims including, before the correlation step, a cleaning step (606) of the 's' signal or the averaged 's' signal*, received by the transducer receiver, said cleaning step comprising a step consisting of smooth the 's' signal or the averaged 's' signal using a low-pass filter to eliminate high-frequency transient disturbances highly energetic parasites.

7. Method according to claim 6 wherein the signal smoothing step 's' or the averaged signal 's' received, defines a smoothed signal $ on a moving average according to the following equation respectively: s(,) = + ï 1 costt,)°*5(1,) + È Los") and where f; are the time samples of the received signal 's' or 's'', and 'N°' is the number of samples on which the moving average is performed.

8. A method according to claim 6 or 7 further comprising a step consisting of setting to zero | the samples of the received signal 's' or 15" or of the smoothed signal, whose amplitude in absolute value is less than one given threshold.

9. A method according to any one of the preceding claims, in in which the correlation step (608) is performed according to the following equation: (way x 50) i=1 s=} ie where Ç is the code consisting of the bits sent at times t, and is the signal received at the receiving transducer, possibly averaged and / or cleaned.

10. Method for detecting defects in an elongated structure acting as an ultrasonic waveguide, said elongated structure being equipped with a plurality of transducers capable of acquiring signals for measuring characteristic quantities of ultrasonic waves guided particles propagating within said elongated structure, each transducer being coupled to an electronic device installed along said structure, this electronic device being configured to process measurement signals received from at least one transducer, the set of Since electronic devices are synchronized to the same clock, the process being implemented by computer and comprising the steps consisting of: - (602, 604) to be carried out between a transmitting transducer and a transducer receiver, at least one operation of transmitting and receiving a wave guided ultrasound in the elongated structure, said ultrasound wave guided corresponding to a modulated signal where the signal is a Y(-t) signal obtained by time reversal of an acquired calibration signal Y(t) between the receiving transducer and the transmitting transducer, and where the mo- modulation is a predefined initial modulation code composed of a bit sequence with 0 and 1; - a step (606) of cleaning the 's' signal or the averaged 's' signal””, received by the receiving transducer, said cleaning step comprising a step consisting of smoothing the 's' signal or the averaged 's' signal to using a low-pass filter to suppress transient disturbances high-energy parasitic high frequencies; - (608) perform peak detection of the signal obtained after cleaning - (610) compare the detection result to a predefined threshold; and - (612) depending on the result of the comparison, determine whether or not there is a defect in the elongated structure between the transmitting transducer and the transducer receiver.

11. | Method according to claim 10, wherein the detection step of peaks of the signal obtained after cleaning are achieved with an operation of thresholding.

12. A method according to claim 10, wherein the detection step of The peaks of the signal obtained after cleaning are done with a procedure of signal processing such as a time-frequency transform or by re- knowledge of motives.

13. A method according to any one of the preceding claims in which the defect determination step (612) includes a step of generate an alert if the comparison result is an in- value less than a predefined threshold.

14. System for detecting defects in an elongated structure acting as an ultrasonic waveguide, said elongated structure being ins- equipped with a plurality of transducers capable of acquiring signals measurement of characteristic quantities of guided ultrasonic waves propagating in said elongated structure, each transducer being coupled with an electronic device installed along said structure, a electronic device configured to process signals from measurements received from at least one transducer, all devices with electronics synchronized to the same clock, the system including means to implement the steps of the process according to any one of claims 1 to 13.

15. Use of the system of claim 14 for railway tracks.

16. Product computer program, said computer program including code instructions to perform the steps of method according to any one of claims 1 to 13, when said The program is executed on a computer.

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