Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
  • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
  • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
  • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
  • G01S15/8909—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration
  • G01S15/8915—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration using a transducer array

Definitions

• the object of the invention relates to a method of reconstructing the profile of a part by means of a transducer or ultrasonic sensor multielements for example, positioned in a medium for the propagation of a wave.
• the invention applies for example for electronic scans using a transmitter element different from a receiver element. It is also used in acquisitions using all the signals transmitted and transmitted element by element of the transducer, of the total capture type or FMC (Full Matrix Capture).
• FMC Full Matrix Capture
• the technique according to the invention is used in particular for two-dimensional or three-dimensional reconstructions of the profile of a part.
• Phased array ultrasonic transducers are increasingly used for non-destructive testing of industrial components. This technology makes it possible to adapt and control an ultrasonic beam within a piece of known geometry by applying delays in transmission and reception to each of the elements of the transducer.
• imaging methods that are based on the calculation of delay laws or flight time are used, it is necessary to have a perfect or complete knowledge of the geometry of the inspected part. If this knowledge is not available, the imaging methods become inoperative or unreliable, and their implementation requires the prior application of a surface reconstruction technique.
• the part whose profile and sensor are to be reconstructed is immersed in a fluid, often in water which serves as coupling.
• a first known technique of the prior art is based on a measurement of the flight times between the elements of the sensor and the surface of the room, and the application of a reconstruction algorithm.
• the measurement of flight time is performed on the signals received during a simple electronic scan.
• FIG. 1 represents this reconstruction technique for an acquisition in transmit / receive, element by element or simple electronic scanning.
• the technique used in the reconstruction consists of sending and receiving with a single element Ej of center C ⁇ and then measuring, at the level of the same element, the flight time of the surface echo, / j.
• the measured time which corresponds to the shortest round-trip time set by the ultrasound to return to the transducer: it therefore corresponds to a specular reflection at normal incidence on the surface of the piece.
• the surface S of the part is locally tangent to this circle at the point P v
• we gets a family of circles r c ⁇ CC 2 , ... ⁇ in the XZ plane.
• the surface of the room is locally tangent to each circle of this family.
• the desired surface is the envelope of the family of circles r c . It can be calculated analytically if we know the curve described by the points C v Indeed, in the case of a linear transducer, the equation of the circle of center C ⁇ c x ,) is given by:
• R c ' is the derivative of R with respect to c x .
• R corresponds to the discrete derivative of the rays R ⁇ . compared to the abscissa of the elements.
• this reconstruction can also be performed using a mono-element sensor by performing a scan along the axis OX.
• One of the drawbacks of this technique is that the mode of emission in electronic scanning, a single element of the transducer per shot, sometimes returns surface echoes of amplitudes too low to achieve a reliable measurement of flight times. This means that, locally, the angle formed by the tangent to the profile and the axis of the sensor is too large, and that the reflected wave does not necessarily reach a transducer receiver. The totality of flight times between the sensor and the surface is therefore not measured and the reconstructed geometry of the part may have significant deviations from the expected profile. Differences can also occur when the surfaces are too irregular and when they generate, for example, several intersecting echoes.
• FTP for All-Points Focusing which mainly applies to signal acquisitions on all the elements forming the reception sensor, of total capture type or "Full Matrix Capture” supra.
• FMC acquisition gives access to data that is often much richer and more complete than those provided by simple electronic scans, particularly in the case of surfaces that are too irregular.
• the complete profile of the piece is then obtained in three stages:
• the set of points obtained then forms the desired profile, and can then be smoothed.
• the number of points forming the profile is not limited by the number of elements N of the sensor.
• Patent FR 2 379 823 describes a method and a device for determining the geometrical configuration of the submerged portion of icebergs by using in particular a reflection point corresponding to a portion of the iceberg by defining the outline of the iceberg as an envelope ellipses.
• offset is used to designate the distance separating a transmitter from a receiver of a transducer, considered in the reference of the transducer.
• transducer refers to a device composed of several elements emitter / receivers of ultrasound or other waves.
• the object of the invention relates to a method for reconstructing a profile of a room, by using a transmitter / receiver device comprising N elements, said device being adapted to emit a wave propagating in a medium, comprising at least the following steps:
• a is the length of the semi-major axis
• b the length of the semi-minor axis of the ellipse
• t flight time of the surface echo
• v speed of propagation of the wave in the medium
• Cx + 1; Cx j -i are the coordinates of the midpoint C j + i or C j -i.
• transceiver pairs ⁇ E ,, R j ⁇ are used such that the distance k is identical for all the transmitting couples. receivers ⁇ ,, R j ⁇ and the above steps are performed to obtain the profile of the part.
• a two-dimensional transceiver device can be used, and the envelope of a two-parameter ellipsoid family can be determined.
• the set of signals associated with the same emitter E is grouped together, and the signals for the (N-1) receivers R j are acquired with i different from j.
• a two-dimensional transceiver device can be used, and the envelope of a two-parameter ellipsoid family can be determined.
• the wave used for the implementation of the method is an ultrasonic wave.
• a threshold value S is used, the envelope of the received signal is compared and if the value of the envelope is lower than the threshold value, an interpolation method is used from the two nearest values to find the missing value.
• FIG. 1 a diagram for a first technique according to the prior art
• FIG. 2 a device configuration for reconstructing a profile of a part
• FIG. 3 an example of reconstruction of a surface according to a first variant embodiment
• FIG. 4 an example of a sequence of the steps of the method of FIG.
• FIG. 5 an example of reconstruction of a surface of a part according to a second variant embodiment
• FIG. 6 an example of a sequence of steps for implementing the method of FIG. 5.
• FIG. 2 represents a part 10 with a sinusoidal profile, immersed in a liquid 11, a multi-element sensor 12 which is connected to a signal processing device 13, in particular adapted to perform the measurement of the flight time and to execute the steps for determining the profile.
• An element 12i comprises for example a transmitter Ei and a receiver Ri.
• the method according to the invention is a technique for determining the profile of a workpiece using an immersion transducer based on a measurement of the flight times between the elements of the sensor and the workpiece, for example its surface.
• the measurement of the flight times is performed on the signals received during a FMC acquisition or an electronic scan by considering an element of the transmitting transducer and a receiving transducer element of different rank.
• FIG. 3 schematizes the reconstruction of a profile of a part according to a first mode of implementation of the method according to the invention, called offset reconstruction.
• the reconstruction by common offset is applied to the data received on a sensor by grouping the signals S, j having the same offset k, that is to say the same distance between a transmitter E, and a receiver R j .
• the data is represented in the offset coordinates h and midpoint Q defined by:
• the process will perform ⁇ / -1 independent reconstructions.
• the method allowing the offset reconstruction having the same value for all the transmitter / receiver pairs comprises, for example, the following steps, FIG. 5:
• equation A By solving the system of equations known to those skilled in the art for the calculation of an envelope of a family of surfaces, equation A.2, the coordinates of the different points P defining the surface of the part in the reference frame are obtained. of the sensor.
• FIG. 4 schematizes the reconstruction of the profile of a surface according to a second variant embodiment.
• the reconstruction of the part profile is applied to the data ordered by firing point, that is to say to the data grouping the set of signals ⁇ S ⁇ S ⁇ , ... ⁇ ⁇ associated with the same emitter E / ' .
• N For a FMC acquisition, we will perform N independent reconstructions.
• b is for example obtained by the formulas (2.5) or (2.5 ') or by
• the method according to this second embodiment executes, for example, the following steps, FIG.
• the method for reconstructing the profile of a part according to the invention performs at least the following steps:
• Step 2 According to the first variant for each offset (or parameter k) or the second variant, for each transmitter / ' , the flight time of the surface echo is measured for each transceiver pair.
• This flight time can be obtained by extracting the time of the maximum of the envelope of the received signal, for example.
• an amplitude threshold S is applied to the envelope of the signal and the flight time corresponding to the surface echo is measured if the maximum of the envelope of the signal is greater than S.
• T (C) corresponding to the flight time of the surface echo as a function of the midpoint C given by (2.3). If the amplitude of the signal received by the surface is less than S, then information on the surface is not available.
• This missing flight time can be determined, for example, by interpolation from the two nearest non-zero T (C) values, to provide a regularly sampled T signal. Note that interpolation of flight times is not a necessary step.
• Step 3 the points Pj of the desired profile are calculated.
• the middle points C ⁇ , length of the half major axis a ⁇ and the half minor axis kj are calculated by (2.3).
• the envelope of the family of ellipses is calculated using formulas (2.4).
• the application of the procedure described above makes it possible to locally reconstruct the points of the profile of the part.
• the desired profile can be obtained, for example, by a polynomial regression on the points reconstructed P
• the profile is described by a polynomial of degree n.
• the reconstructed profile is presented, for example, in a CAD file format.
• the profile is described by segments connecting the set of reconstructed points P v.
• the number of reconstructed points can be reduced by means of facet reduction methods such as, for example, the radius of curvature method or linearization linear regression method. It is also possible to use other known methods for smoothing the points obtained and present the profile in a more easily exploitable format or according to the processing implemented.
• FIG. 5 represents an exemplary implementation of the first variant of the method.
• the FMC acquisition was performed in immersion, on a piece with a sinusoidal profile, as shown in Figure 2.
• the control is performed using a linear sensor 2MHz opening 89.4 mm and composed of 64 elements of width 1 .2 mm.
• the material constituting the piece is homogeneous and made of stainless steel.
• the examples given in relation to FIGS. 2 to 6 may be used with waves other than ultrasonic waves and a propagation medium different from water.
• waves other than ultrasonic waves and a propagation medium different from water.
• the propagation medium may be a fluid, a gas or a solid medium having good propagation properties.
• the method according to the invention has notably the following advantages: a faster determination of the profile and simplicity of implementation while considering a number of processed data larger than the number used in the electronic scanning technique according to the prior art.

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• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Physics & Mathematics (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2013
  • 2013-11-22 FR FR1361502A patent/FR3013850B1/fr not_active Expired - Fee Related
• 2014
  • 2014-11-20 EP EP14802033.2A patent/EP3071992A1/fr not_active Withdrawn
  • 2014-11-20 US US15/036,758 patent/US20160299226A1/en not_active Abandoned
  • 2014-11-20 JP JP2016533022A patent/JP2017500553A/ja active Pending
  • 2014-11-20 WO PCT/EP2014/075145 patent/WO2015075121A1/fr active Application Filing
  • 2014-11-20 CA CA2931167A patent/CA2931167A1/en not_active Abandoned

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