WO2012031616A1 - Linear position sensor - Google Patents

Linear position sensor Download PDF

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Publication number
WO2012031616A1
WO2012031616A1 PCT/EP2010/005934 EP2010005934W WO2012031616A1 WO 2012031616 A1 WO2012031616 A1 WO 2012031616A1 EP 2010005934 W EP2010005934 W EP 2010005934W WO 2012031616 A1 WO2012031616 A1 WO 2012031616A1
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WO
WIPO (PCT)
Prior art keywords
target
track
winding
loops
secondary winding
Prior art date
Application number
PCT/EP2010/005934
Other languages
French (fr)
Inventor
Jérémie BLANC
Alain Fontanet
Jean-Louis Roux
Bertrand Vaysse
Original Assignee
Continental Automotive France
Continental Automotive Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Automotive France, Continental Automotive Gmbh filed Critical Continental Automotive France
Publication of WO2012031616A1 publication Critical patent/WO2012031616A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
    • G01D5/2053—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by a movable non-ferromagnetic conductive element

Definitions

  • the invention belongs to the field of position sensors and relates to a linear position sensor without contact. These sensors deliver a signal substantially proportional to the position of a target over a measurement range.
  • this measuring range is said to be linear, that is to say that the sensor delivers a position information only according to a coordinate in space, this coordinate being Cartesian or polar, speaks in the latter case of circular sensor or "resolver”.
  • a "linear sensor” designates any type of sensor delivering a position information according to a single coordinate, whether the displacement of the target is rectilinear or rotary.
  • the invention relates to the field of so-called inductive sensors.
  • This type of sensor is known to those skilled in the art and only the elements necessary for understanding the advantages of the invention are described below.
  • winding refers to any loop pattern described by an electrical conductor.
  • the winding can describe these loops in a helical path around an axis or along spiral paths on a plane or in a repeating pattern extending over one or more parallel planes.
  • the INDUCTOSYN® sensors are examples of inductive sensors. All these sensors have in common to measure the displacement of a target and to include a primary winding, powered by a high frequency alternating current, which induces a voltage in a secondary winding. The displacement of the target modifies the coupling between the primary winding and the secondary winding, the position of the latter being deduced from the measurement of the voltage across the secondary winding.
  • EP 0182085 describes as such a position sensor where the primary winding and the secondary winding are placed on a track.
  • Figure 1 shows schematically the constitution of such a sensor.
  • the target is made of an electrically conductive material and moves relative to both windings.
  • the track (100) comprises a primary winding (10), which is fed by a high frequency alternating current, the latter generally being between a few KHz and a few MHz, and a secondary winding (11).
  • the secondary winding (11) comprises two loops (110, 111). Compared to the direction of the current (15), the winding directions of the loops (110, 111) of the secondary winding are reversed so that the voltages induced in each of these loops by the current (15) flowing in the winding primary (10) are equal in amplitude but opposite in polarity.
  • the voltages in the two loops (110, 111) of the secondary winding (11) are balanced and the voltage measured at the terminals of this winding is zero.
  • the magnetic field produced by the current (15) flowing in the primary winding (10) induces in the target (200) a an electric field which, in turn, produces a current density which generates a magnetic field, which opposes the magnetic field generated by the primary winding (10).
  • Fig. 1B when such a target (200) is moving relative to the track, the magnitude of the measured voltage (102) across the secondary winding varies depending on the difference in area covered by the target. (200) on each of the loops (110, 111).
  • the target (200) during its displacement first progressively covers the first loop (110) of the secondary winding (11) and then the second loop (111) of this winding. Initially (position I) the target does not cover any of the loops and the amplitude of the voltage measured across the secondary winding is zero, the voltages in the two loops equilibrium.
  • the loops (110, 111) follow on the surface of the track a geometrical crenellated pattern
  • the target (200) is of rectangular shape, its length being substantially equivalent to the pitch of said slots.
  • such a sensor By demodulating the voltage measured across the secondary winding, such a sensor delivers a theoretical signal (103) for the evolution of the voltage (102), between -V and + V, as a function of the displacement (101) of the target (200) whose variation is a function of the secondary winding surface covered by the target (200).
  • this theoretical function (103) is linear.
  • the output voltage measured at the terminals of the secondary windings is also influenced by other factors such as changes in the spacing between the target and the track in a plane perpendicular to the plane of the track, referred to as "air gap". or parallelism errors between the measurement direction and the relative displacement axis of the target with respect to the track.
  • one of the solutions of the prior art is to use several secondary windings and to combine the measurements obtained on each of these windings to compensate for these effects.
  • the senor comprises a first secondary winding (21 1) comprising loops whose shape combined with the shape of the target produces a variation in the amplitude of the voltage.
  • V ! measured at its terminals as a function of the displacement x of the target (200) in the longitudinal direction (1000), in the following theoretical form:
  • K 1 and Pi being constants, L the length of the useful measurement range of the sensor, and x the position of the target.
  • It also comprises a second secondary winding (212) producing, as a function of the position x of the target (200) in the longitudinal direction (1000), a variation of the amplitude V 2 of the voltage at its terminals, according to a theoretical function. of shape :
  • the position x of the target (200) in the longitudinal direction (1000) is obtained by calculating the ratio of ⁇ by V 2 and calculating the arc-tangent function of this ratio.
  • V 2 K 2 cos (p7tx / L) + B
  • the invention proposes a device for measuring the inductive type of the position in a longitudinal direction of a target, characterized in that it comprises:
  • a moving target capable of moving parallel to the longitudinal axis of the track without contact therewith and able to modify the current induced by the primary winding in the secondary winding according to its relative position relative to the track in the longitudinal direction;
  • the secondary winding further comprising a compensation loop able to eliminate a component independent of the position of the target in the inductive coupling between the primary winding and the secondary winding.
  • This compensation loop makes it possible to eliminate the DC component (A or B above) and thus to facilitate the processing of the signal coming from this sensor and to improve its accuracy.
  • the present invention may be implemented according to various advantageous embodiments set forth below, which may be considered individually or in any technically operative combination.
  • the invention is not limited to rectilinear tracks and the longitudinal axis of the track can advantageously be a circular axis, the device can thus be used to form a resolver.
  • the device according to the invention comprises a second secondary winding organized according to a periodic repetition of loops.
  • this second secondary winding comprises a compensation loop able to eliminate a component independent of the position of the target in the inductive coupling between the primary winding and this secondary winding.
  • this compensation by combination of the signals is more easily achieved if the periodic repetitions of the loops of the two secondary windings are carried out according to the same period.
  • the repetitions of the loops of the two secondary windings are out of phase by a quarter of a period. This feature allows the combination of measurement by the combination of even and odd functions and thus simplify signal processing.
  • the device of the invention uses a target whose length is greater than or equal to the length of the track so that the target is able to cover the entire track.
  • the progressive coverage of the track has an integration effect which produces an evolution of the amplitude of the signals measured at the terminals of each secondary winding as a function of the position of the target, being able, at least over a range, to be assimilated to Sine and cosine functions, whatever the form of windings, as long as they are periodic and out of phase by a quarter of a period.
  • This feature allows for cost-effective sensors by increasing manufacturing tolerances or increasing the usable length of a given track by reducing sensitivity to edge effects.
  • the invention also relates to a method for measuring a position or displacement using a device according to any of the embodiments comprising two secondary windings as described above, comprising the steps of:
  • This method takes advantage of the characteristics of the device, and in particular the compensation of the DC components on the two secondary windings for improve the accuracy of the measurement.
  • the measurement method uses a device comprising two secondary windings comprising a periodic repetition of loops according to the same period on the two secondary windings, whose repetitions are out of phase by a quarter of a period and a target of length greater than the length of the track, the non-linear function being the arc tangent of the ratio of the amplitudes of the voltages measured at the terminals of a first and a second secondary winding.
  • the presence of compensation loops makes it possible to take full advantage of the integration effect obtained by this type of target, by improving the repeatability of the characteristics of this type of sensor manufactured in series.
  • FIGS. 1 to 6 in which:
  • FIG. 1 relating to the prior art shows a device for measuring the position of a target in a view from above, between two extreme positions of the target FIG. 1B, and FIG. 1C an evolution diagram. the measurement delivered by such a device on the useful length of the target;
  • FIG. 2 shows in an overhead view an exemplary embodiment of a sensor comprising two secondary windings capable of delivering a sinusoidal signal as a function of the longitudinal position of the target;
  • FIG. 3 is a top view of a particular embodiment of the invention in which one of the secondary windings comprises a compensation loop;
  • FIG. 4 is a top view of FIGS. 4A, 4B and 4C, an exemplary embodiment of the invention comprising two crenellated secondary windings, one of which comprises a compensation loop and a target of length greater than or equal to of the track:
  • FIG. 4A when the target is at the beginning of the measurement range of the sensor
  • FIG. 4B when the target is substantially at the end of the measuring range of the track
  • FIG. 4C the result observed on the signals delivered by such a sensor with and without compensation loop
  • FIG. 5 shows in plan view an exemplary embodiment of a sensor circular track capable of measuring the angular position of the leading edge of a target, the track comprising two secondary windings in slots each comprising a compensation loop;
  • FIG. 6 shows examples of modification of the signal delivered by a sensor with and without the addition of compensation loops:
  • FIG. 6A On the cosine function, FIG. 6A,
  • FIG. 6B On the sinus function, FIG. 6B and
  • FIG. 3 according to an exemplary embodiment of the device according to the invention, comprises a track 350 extending along a longitudinal axis 1000 corresponding to the axis on which the coordinate of position of the target 200, coordinated with which the measurement delivered by the measuring device is proportional.
  • the track comprises a primary winding 10, a first secondary winding 211 comprising a plurality of loops in a sinusoidal periodic pattern and a second secondary winding 212 having a plurality of loops also describing a sinusoidal periodic pattern, shifted by a quarter of a period relative to to the loops of the first secondary winding.
  • the spatial organization of the loops and windings means that when the track is not covered by a target 200, the voltages induced across the two secondary windings 211, 212 are zero.
  • the device further comprises means (not shown) for supplying the primary winding with a high frequency AC voltage current, means (not shown) capable of measuring and demodulating the voltage across the secondary windings 211, 212 and signal processing means, not shown, capable of performing operations on the signals measured at the terminals of the secondary windings, so as to deliver a measurement proportional to the relative position of the target on the longitudinal axis 1000 of the track.
  • the target 200 of width substantially equal to that of the track 350 and of length substantially equal to half a period of the pattern described by the loops of the secondary windings 211, 212, is able to move in a plane parallel to that of the track and parallel to its longitudinal axis 100.0 so as to cover, without contact, a portion of the surface of the secondary windings 211, 212. This movement takes place at a substantially constant distance from the track 350.
  • each secondary winding 211, 212 delivers, after demodulation of the voltage measured at its terminals, a signal that varies significantly with the displacement of the target 200 as the area of this coil covered by the target 200.
  • Each winding 210, 211 describing loops in a sinusoidal pattern the delivered signals are comparable to a sine and a cosine whose ratio provides a tangent and from which the arc tangent can be calculated to obtain substantially linear information as a function of the position of the target 200 on the track 350.
  • This treatment works as soon as the surface of the track having secondary windings is covered by a surface substantially constant target, so that the two secondary windings 21 1, 212 provide sine and cosine signals. This condition is verified substantially between the position A and the position B of the target 200 so that the useful measurement range of such a sensor is of the order of half the length of its track 350.
  • the voltages induced in the two loops 2121, 2122 of this winding in the absence of a target covering a part of it are balanced so that the voltage measured at the terminals of this second winding 212 is zero in the absence of a target. If the signal delivered by this second winding during the path of the target 200 is not centered, the addition of a compensation loop 310 on one of the loops of this winding compensates for this effect. Such decentering of the signal can be related to different constructive aspects of the sensor.
  • the two secondary windings 211, 212 may be deposited on two different faces of the track 350 so that the distance between the target 200 and each of these secondary windings 211, 212 is different as its effect on the inductive coupling.
  • the displacement of the target may not be exactly parallel to the track 350, or have a parallelism defect with respect to the longitudinal axis 1000 thereof.
  • this compensation loop 310 extends one of the loops 2122 of this secondary winding 212 so that the voltages induced between the two loops 2121, 2122 do not balance more accurately in the absence of a target. overlying them, this imbalance of the voltages compensating for the signal shifting produced by this winding 212 as a function of the displacement of the target 200.
  • the target 400 has a length greater than or equal to the measuring range of the track 450 and covers all of it during its journey.
  • the track 450 comprises a primary winding 10 and two secondary windings 411, 412 describing periodically patterned loops phase-shifted spatially by a quarter period between the two windings 41 1, 412.
  • the repetitive patterns described by these loops can be of any shape, in this example it is a crenellated pattern.
  • This phenomenon comparable to an integration of the signal delivered as a function of the variation of the area of each winding 411, 412 covered by the target 400, is particularly advantageous because it makes it possible to increase the useful measurement range of the sensor which is then close to the length of the track 450.
  • the mode of treatment nt signal to achieve the position measurement becomes particularly sensitive to the decentering of the sinusoidal functions 403, 404 obtained.
  • the addition of a compensation loop on at least one 411 of the secondary windings 411, 412 compensates for this type of effect and to obtain a signal 403 'recentered.
  • the track 550 may be circular in shape, the longitudinal axis 5000 then being a circular axis. This configuration makes it possible to measure the displacement of the leading edge 501 of a target 500 also circular when said target moves in rotation about an axis 530 corresponding to the center of gyration of the track 550.
  • the track comprises a primary winding 513 fed by a high-frequency alternating voltage current, and two secondary windings 511, 512 whose loops reproduce period-shifted periodic units of a quarter of a period.
  • the geometry of the winding loops shown in the various figures has no other purpose than to illustrate the principle and that the actual geometry of the loops can be much more complex, since This is a periodic pattern.
  • the two secondary windings are phase shifted by a quarter period.
  • the sensor measures the angular displacement ⁇ of the leading edge 501 of the target 500.
  • the configuration of this embodiment with a target 500 covering an angular sector equal to or greater than that covered by the track 550 and able to cover the entire amplitude of measurement, is equivalent technical effect to the case of the straight track 450 shown supra Figure 4. It increases the useful measurement range with respect to known sensors of the prior art, which is particularly advantageous in the case of a resolver where the extension possibilities of the track 550 are limited by its circular shape.
  • the invention is also particularly advantageous in this embodiment where the sources of decentering of the signal, if only by constructive aspects of the sensor, are potentially more numerous.
  • defects in the circularity of the track 550 and the target 500, the concentricity of the two, the haze of one or the other are factors likely to create a decentering of the signals and expensive to settle in a mass production economy. These defects are advantageously compensated, to bring them back to an acceptable level as a function of the targeted accuracy, by the addition of compensation loops 510, 514 on one of the secondary windings or on both 51 1, 512.
  • FIG. 6 gives an example of the modification of the variation of the signals 603, 603 ', 603 ", 604, 604' 604" obtained at the terminals of the secondary windings 41 1, 51 1, 412, 512 of an inductive sensor corresponding to various embodiments of the invention with and without a compensation loop and the signal 605, 605 ', 605 "calculated from these signals as a function of the displacement 601 of a target
  • the track comprises two secondary windings each comprising a periodic repetition of loops whose geometry, combined with the shape of the leading edge of the target, is capable of producing a variation of the voltage across the winding according to a sinusoidal function as a function of the position 601 of
  • the repetition periods of the loops of the two secondary windings are identical but spatially offset from one another by a quarter of a period, so that one of the secondary windings produces a variation of the ampli study 602 of the voltage measured at its terminals, according to a sine function 604, 604 ', 604 ", FIG
  • FIG. 6A represents an example of an evolution of the amplitude of the signal measured at the terminals of a secondary winding delivering an amplitude variation 602 in cosine with the displacement 601 of the target, according to two examples of signals comprising a component independent of the displacement 603 ', 603 "and after adding a compensation loop on this winding, curve 603.
  • FIG. 6B shows an example of an evolution of the amplitude of the signal at the terminals of the secondary winding delivering a sinus variation 604 , 604 ', 604 "of said amplitude 602 with the displacement 601 of the target, in the presence of an invariable component 604 ', 604 "and after the addition of a compensation loop to this winding, curve 604.
  • FIG. 6A represents an example of an evolution of the amplitude of the signal measured at the terminals of a secondary winding delivering an amplitude variation 602 in cosine with the displacement 601 of the target, according to two examples of signals comprising a component independent of the displacement
  • 6C shows the result after calculation of the arc function.
  • tangent which delivers the measured position 606 of the target as a function of its position 601 on the track, from the ratio of the amplitudes of the signals Compared to the arc-tangent function 605 corresponding to the calculation made from the ratio of the amplitudes 604, 603 'signals obtained in the presence of compensation loops, the changes of the functions 605', 605 "calculated from the ratios of the amplitudes of the signals 603 ', 604', 603", 604 "measured across the secondary windings not including compensation loop, differ from the nominal function 605 both in value and slope.
  • the decentering component of the signal and independent of the position of the target is less than 10% of the amplitude of the variation of the amplitude of the signal over the useful measurement range. It is clear from these examples that the presence of compensation loops significantly improves the accuracy of the sensor over the entire measurement range.

Abstract

The invention relates to the field of positions sensors and in particular to the field of inductive sensors. The device of the invention comprises a track (550) including a primary winding (513) supplied with a high-frequency alternating current and a plurality of secondary windings (511, 512). The device measures the position of the leading edge (501) of a target (500) between a first position in which the target does not overlap the track (550) and a second position in which the target (500) covers all of the track (550). The secondary windings (511, 512) comprise compensation loops (510, 514) that can eliminate components independent of the position of the target (500) in the variation of the amplitude of the voltages delivered by the secondary windings (511, 512) as a function of the position θ of the leading edge (501) of the target (500).

Description

Capteur de position linéaire  Linear position sensor
L'invention appartient au domaine des capteurs de position et concerne un capteur de position linéaire sans contact. Ces capteurs délivrent un signal sensiblement proportionnel à la position d'une cible sur une étendue de mesure. Dans le cas de l'invention, cette étendue de mesure est dite linéaire, c'est-à-dire que le capteur ne délivre une information de position que selon une coordonnée dans l'espace, cette coordonnée pouvant être cartésienne ou polaire, on parle dans ce dernier cas de capteur circulaire ou de « resolver ». Dans la suite, un « capteur linéaire » désigne tout type de capteur délivrant une information de position selon une seule coordonnée, que le déplacement de la cible soit rectiligne ou rotatif.  The invention belongs to the field of position sensors and relates to a linear position sensor without contact. These sensors deliver a signal substantially proportional to the position of a target over a measurement range. In the case of the invention, this measuring range is said to be linear, that is to say that the sensor delivers a position information only according to a coordinate in space, this coordinate being Cartesian or polar, speaks in the latter case of circular sensor or "resolver". In the following, a "linear sensor" designates any type of sensor delivering a position information according to a single coordinate, whether the displacement of the target is rectilinear or rotary.
Ce type de capteur trouve de très nombreuses applications industrielles partout où il est nécessaire de définir la position d'un élément mécanique, on peut citer les règles de mesure des machines outils, des capteurs de position de levier de vitesse dans l'automobile, des capteurs de position de manettes de gaz ou de commande de volets dans l'aéronautique ou la construction navale, sans que cette liste ne soit exhaustive.  This type of sensor finds many industrial applications wherever it is necessary to define the position of a mechanical element, we can cite the measurement rules of machine tools, position sensors of speed lever in the automobile, position sensors for throttles or shutter control in the aeronautics or shipbuilding industry, without this list being exhaustive.
Plus particulièrement, l'invention concerne le domaine des capteurs dits inductifs. Ce type de capteurs est connu de l'homme du métier et seuls les éléments nécessaires à la compréhension des avantages de l'invention sont exposés ci-après.  More particularly, the invention relates to the field of so-called inductive sensors. This type of sensor is known to those skilled in the art and only the elements necessary for understanding the advantages of the invention are described below.
Le terme « enroulement » désigne tout motif en boucle décrit par un conducteur électrique. L'enroulement peut décrire ces boucles selon une trajectoire hélicoïdale autour d'un axe ou selon des trajectoires en spirale sur un plan ou encore selon un motif répétitif s'étendant sur un ou plusieurs plans parallèles.  The term "winding" refers to any loop pattern described by an electrical conductor. The winding can describe these loops in a helical path around an axis or along spiral paths on a plane or in a repeating pattern extending over one or more parallel planes.
Les capteurs INDUCTOSYN®, ou les capteurs décrits dans le brevet européen EP 0182085, sont des exemples de capteurs inductifs. Tous ces capteurs ont en commun de mesurer le déplacement d'une cible et de comporter un enroulement primaire, alimenté par un courant alternatif à haute fréquence, lequel induit une tension dans un enroulement secondaire. Le déplacement de la cible modifie le couplage entre l'enroulement primaire et l'enroulement secondaire, la position de la celle-ci est déduite de la mesure de la tension aux bornes de l'enroulement secondaire.  The INDUCTOSYN® sensors, or the sensors described in the European patent EP 0182085, are examples of inductive sensors. All these sensors have in common to measure the displacement of a target and to include a primary winding, powered by a high frequency alternating current, which induces a voltage in a secondary winding. The displacement of the target modifies the coupling between the primary winding and the secondary winding, the position of the latter being deduced from the measurement of the voltage across the secondary winding.
EP 0182085 décrit à ce titre un capteur de position où l'enroulement primaire et l'enroulement secondaire sont placés sur une piste. La figure 1 représente schématiquement la constitution d'un tel capteur. La cible est constituée d'un matériau électriquement conducteur et se déplace relativement aux deux enroulements.  EP 0182085 describes as such a position sensor where the primary winding and the secondary winding are placed on a track. Figure 1 shows schematically the constitution of such a sensor. The target is made of an electrically conductive material and moves relative to both windings.
Sur la figure 1A, selon un exemple simple de réalisation, la piste (100) comprend un enroulement primaire (10), lequel est alimenté par un courant alternatif à haute fréquence, celle-ci étant généralement comprise entre quelques KHz et quelques MHz, et un enroulement secondaire (11 ). Dans cet exemple, l'enroulement secondaire (11 ) comprend deux boucles (110,111). Comparés au sens du courant (15), les sens d'enroulement des boucles (110, 111 ) de l'enroulement secondaire sont inversés de sorte que les tensions induites dans chacune de ces boucles par le courant (15) circulant dans l'enroulement primaire (10) sont égales en amplitude mais opposées en polarité. En l'absence de cible, les tensions dans les deux boucles (110, 111) de l'enroulement secondaire (11) s'équilibrent et la tension mesurée aux bornes de cet enroulement est nulle. Sur la figure 1 B, en présence d'une cible (200) constituée d'un matériau électriquement conducteur, le champ magnétique produit par le courant (15) circulant dans l'enroulement primaire (10) induit dans la cible (200) un champ électrique qui, à son tour, produit une densité de courant qui engendre un champ magnétique, lequel s'oppose au champ magnétique généré par l'enroulement primaire (10). In FIG. 1A, according to a simple example of embodiment, the track (100) comprises a primary winding (10), which is fed by a high frequency alternating current, the latter generally being between a few KHz and a few MHz, and a secondary winding (11). In this example, the secondary winding (11) comprises two loops (110, 111). Compared to the direction of the current (15), the winding directions of the loops (110, 111) of the secondary winding are reversed so that the voltages induced in each of these loops by the current (15) flowing in the winding primary (10) are equal in amplitude but opposite in polarity. In the absence of a target, the voltages in the two loops (110, 111) of the secondary winding (11) are balanced and the voltage measured at the terminals of this winding is zero. In FIG. 1B, in the presence of a target (200) made of an electrically conductive material, the magnetic field produced by the current (15) flowing in the primary winding (10) induces in the target (200) a an electric field which, in turn, produces a current density which generates a magnetic field, which opposes the magnetic field generated by the primary winding (10).
Sur la figure 1 B, lorsqu'une telle cible (200) se déplace relativement à la piste, l'amplitude de la tension mesurée (102) aux bornes de l'enroulement secondaire varie en fonction de la différence de surface couverte par la cible (200) sur chacune des boucles (110, 111). Selon l'exemple de la figure 1 B, la cible (200) au cours de son déplacement recouvre d'abord progressivement la première boucle (110) de l'enroulement secondaire (11 ) puis la deuxième boucle (111) de cet enroulement. Initialement (position I) la cible ne recouvre aucune des boucles et l'amplitude de la tension mesurée aux bornes de l'enroulement secondaire est nulle, les tensions dans les deux boucles s'équilibrant. Selon cet exemple de réalisation, les boucles (110, 111) suivent à la surface de la piste un motif géométrique en créneau, la cible (200) est de forme rectangulaire, sa longueur étant sensiblement équivalente au pas desdits créneaux. Ainsi, lorsque la cible recouvre l'intégralité de la première boucle (110) de l'enroulement secondaire (1 1), l'amplitude de la tension aux bornes de celui-ci est équivalente à celle de la tension induite dans la deuxième boucle (111). Lorsque la cible (200) recouvre (position II) une surface égale des deux boucles (1 10, 111), l'amplitude de la tension mesurée aux bornes de l'enroulement secondaire est nulle. Puis, lorsque la cible (200) recouvre intégralement la deuxième boucle (111), l'amplitude de la tension mesurée aux bornes de l'enroulement secondaire (1 1 ) est équivalente à celle de la tension induite dans la première boucle (110). Finalement (position III), l'amplitude de la tension mesurée aux bornes de l'enroulement secondaire (11 ) tend à nouveau vers zéro, lorsque la cible (200) ne recouvre plus la deuxième boucle (1 11) et que les tensions dans les deux boucles s'équilibrent à nouveau. In Fig. 1B, when such a target (200) is moving relative to the track, the magnitude of the measured voltage (102) across the secondary winding varies depending on the difference in area covered by the target. (200) on each of the loops (110, 111). According to the example of FIG. 1B, the target (200) during its displacement first progressively covers the first loop (110) of the secondary winding (11) and then the second loop (111) of this winding. Initially (position I) the target does not cover any of the loops and the amplitude of the voltage measured across the secondary winding is zero, the voltages in the two loops equilibrium. According to this exemplary embodiment, the loops (110, 111) follow on the surface of the track a geometrical crenellated pattern, the target (200) is of rectangular shape, its length being substantially equivalent to the pitch of said slots. Thus, when the target covers the entirety of the first loop (110) of the secondary winding (1 1), the amplitude of the voltage across it is equivalent to that of the voltage induced in the second loop (111). When the target (200) covers (position II) an equal area of the two loops (1 10, 111), the amplitude of the voltage measured across the secondary winding is zero. Then, when the target (200) completely covers the second loop (111), the amplitude of the voltage measured across the secondary winding (1 1) is equivalent to that of the voltage induced in the first loop (110) . Finally (position III), the amplitude of the voltage measured across the secondary winding (11) tends to zero again, when the target (200) no longer covers the second loop (1 11) and the voltages in the two loops balance again.
En démodulant la tension mesurée aux bornes de l'enroulement secondaire, un tel capteur délivre un signal théorique (103) d'évolution de la tension (102), entre -V et +V, en fonction du déplacement (101 ) de la cible (200) dont la variation est fonction de la surface d'enroulement secondaire recouverte par la cible (200). Dans cet exemple de réalisation, où les boucles décrivent des créneaux et où la cible est de forme rectangulaire, cette fonction théorique (103) est linéaire.  By demodulating the voltage measured across the secondary winding, such a sensor delivers a theoretical signal (103) for the evolution of the voltage (102), between -V and + V, as a function of the displacement (101) of the target (200) whose variation is a function of the secondary winding surface covered by the target (200). In this embodiment, where the loops describe slots and where the target is of rectangular shape, this theoretical function (103) is linear.
La tension de sortie mesurée aux bornes des enroulements secondaires est également influencée par d'autres facteurs tels que des modifications de l'écartement entre la cible et la piste dans un plan perpendiculaire au plan de la piste, désigné par « air gap » en anglais, ou encore des erreurs de parallélisme entre la direction de mesure et l'axe de déplacement de relatif de la cible par rapport à la piste.  The output voltage measured at the terminals of the secondary windings is also influenced by other factors such as changes in the spacing between the target and the track in a plane perpendicular to the plane of the track, referred to as "air gap". or parallelism errors between the measurement direction and the relative displacement axis of the target with respect to the track.
De manière à corriger, au moins partiellement, ces effets indésirables, une des solutions de l'art antérieur consiste à utiliser plusieurs enroulements secondaires et à combiner les mesures obtenues sur chacun de ces enroulements pour compenser ces effets.  In order to correct, at least partially, these undesirable effects, one of the solutions of the prior art is to use several secondary windings and to combine the measurements obtained on each of these windings to compensate for these effects.
À titre d'exemple de ce mode de réalisation, sur la figure 2, le capteur comprend un premier enroulement secondaire (21 1 ) comportant des boucles dont la forme combinée avec la forme de la cible produit une variation de l'amplitude de la tension V! mesurée à ses bornes en fonction du déplacement x de la cible (200) dans la direction longitudinale (1000), sous la forme théorique suivante : As an example of this embodiment, in FIG. 2, the sensor comprises a first secondary winding (21 1) comprising loops whose shape combined with the shape of the target produces a variation in the amplitude of the voltage. V ! measured at its terminals as a function of the displacement x of the target (200) in the longitudinal direction (1000), in the following theoretical form:
\ = KiSin(pi7D(/L),  \ = KiSin (pi7D (/ L),
K1 et Pi étant des constantes, L la longueur de la plage utile de mesure du capteur, et x la position de la cible. K 1 and Pi being constants, L the length of the useful measurement range of the sensor, and x the position of the target.
II comprend également un second enroulement (212) secondaire produisant en fonction de la position x de la cible (200) dans la direction longitudinale (1000), une variation de l'amplitude V2 de la tension à ses bornes, selon une fonction théorique de la forme :It also comprises a second secondary winding (212) producing, as a function of the position x of the target (200) in the longitudinal direction (1000), a variation of the amplitude V 2 of the voltage at its terminals, according to a theoretical function. of shape :
Figure imgf000005_0001
Figure imgf000005_0001
La position x de la cible (200) selon la direction longitudinale (1000) est obtenue en calculant le rapport de \ par V2 et en calculant la fonction arc-tangente de ce rapport. The position x of the target (200) in the longitudinal direction (1000) is obtained by calculating the ratio of \ by V 2 and calculating the arc-tangent function of this ratio.
Or, en pratique, les amplitudes des tensions Vi et V2 mesurées aux bornes des deux enroulements secondaires (21 1 , 212) varient en réalité selon des fonctions : V^K^infpnx/L) + A However, in practice, the amplitudes of the voltages V 1 and V 2 measured across the two secondary windings (21 1, 212) vary in fact according to functions: V ^ K ^ infpnx / L) + A
V2=K2cos(p7tx/L) + B V 2 = K 2 cos (p7tx / L) + B
de sorte que le rapport des amplitudes des deux tensions ne fournit plus un signal proportionnel à une fonction tangente en fonction du déplacement 'x' de la cible (200). Bien que ces effets puissent être, au moins partiellement, corrigés par un traitement numérique du signal mesuré, celui-ci requiert un étalonnage et une calibration individuelle de la piste pour chaque capteur ainsi réalisé. Ces opérations sont longues et incompatibles avec la production en série de tels capteurs. so that the ratio of the amplitudes of the two voltages no longer provides a signal proportional to a tangent function as a function of the displacement 'x' of the target (200). Although these effects may be at least partially corrected by digital processing of the measured signal, this requires calibration and individual calibration of the track for each sensor thus produced. These operations are long and incompatible with the mass production of such sensors.
Pour résoudre cet inconvénient de l'art antérieur, l'invention propose un dispositif de mesure de type inductif de la position selon une direction longitudinale d'une cible caractérisé en ce qu'il comprend :  To solve this disadvantage of the prior art, the invention proposes a device for measuring the inductive type of the position in a longitudinal direction of a target, characterized in that it comprises:
• une piste s'étendant selon un axe longitudinal parallèle à la direction de mesure, laquelle piste comprend un enroulement primaire apte à induire un courant électrique dans un enroulement secondaire organisé selon une répétition périodique de boucles ;  A track extending along a longitudinal axis parallel to the measurement direction, which track comprises a primary winding capable of inducing an electric current in a secondary winding organized according to a periodic repetition of loops;
• une cible mobile apte à se déplacer parallèlement à l'axe longitudinal de la piste sans contact avec celle-ci et apte à modifier le courant induit par l'enroulement primaire dans l'enroulement secondaire en fonction de sa position relative par rapport à la piste selon la direction longitudinale ;  A moving target capable of moving parallel to the longitudinal axis of the track without contact therewith and able to modify the current induced by the primary winding in the secondary winding according to its relative position relative to the track in the longitudinal direction;
· l'enroulement secondaire comportant en outre une boucle de compensation apte à éliminer une composante indépendante de la position de la cible dans le couplage inductif entre l'enroulement primaire et l'enroulement secondaire. La présence de cette boucle de compensation permet de supprimer la composante continue (A ou B ci dessus) et ainsi de faciliter le traitement du signal issu de ce capteur et d'en améliorer la précision.  The secondary winding further comprising a compensation loop able to eliminate a component independent of the position of the target in the inductive coupling between the primary winding and the secondary winding. The presence of this compensation loop makes it possible to eliminate the DC component (A or B above) and thus to facilitate the processing of the signal coming from this sensor and to improve its accuracy.
La présente invention peut être mise en œuvre selon différents modes de réalisation avantageux exposés ci-après, lesquels peuvent être considérés individuellement ou selon toute combinaison techniquement opérante.  The present invention may be implemented according to various advantageous embodiments set forth below, which may be considered individually or in any technically operative combination.
L'invention ne se limite pas aux pistes rectilignes et l'axe longitudinal de la piste peut avantageusement être un axe circulaire, le dispositif peut ainsi être utilisé pour constituer un resolver.  The invention is not limited to rectilinear tracks and the longitudinal axis of the track can advantageously be a circular axis, the device can thus be used to form a resolver.
Selon un mode de réalisation préféré, le dispositif objet de l'invention comprend un deuxième enroulement secondaire organisé selon une répétition périodique de boucles. Cette caractéristique permet d'améliorer la résolution du capteur. Avantageusement, ce deuxième enroulement secondaire comprend une boucle de compensation apte à éliminer une composante indépendante de la position de la cible dans le couplage inductif entre l'enroulement primaire et cet enroulement secondaire. Ainsi, les mesures effectuées aux bornes de chaque enroulement secondaire peuvent être combinées selon des fonctions complexes, notamment non linéaires, de sorte à compenser l'effet de certains facteurs liés aux tolérances de fabrication et de mise en œuvre de ces capteurs. According to a preferred embodiment, the device according to the invention comprises a second secondary winding organized according to a periodic repetition of loops. This feature improves the resolution of the sensor. Advantageously, this second secondary winding comprises a compensation loop able to eliminate a component independent of the position of the target in the inductive coupling between the primary winding and this secondary winding. Thus, the measurements made at the terminals of each secondary winding can be combined according to complex functions, in particular non-linear functions, so as to compensate the effect of certain factors related to the manufacturing and implementation tolerances of these sensors.
Selon un exemple de réalisation, cette compensation par combinaison des signaux est plus aisément réalisée si les répétitions périodiques des boucles des deux enroulements secondaires sont réalisées selon la même période.  According to an exemplary embodiment, this compensation by combination of the signals is more easily achieved if the periodic repetitions of the loops of the two secondary windings are carried out according to the same period.
Avantageusement, les répétitions des boucles des deux enroulements secondaires sont déphasées d'un quart de période. Cette caractéristique permet de la combinaison de mesure par l'association de fonctions paires et impaires et ainsi de simplifier le traitement du signal.  Advantageously, the repetitions of the loops of the two secondary windings are out of phase by a quarter of a period. This feature allows the combination of measurement by the combination of even and odd functions and thus simplify signal processing.
Selon un mode de réalisation particulièrement avantageux utilisant cette caractéristique, le dispositif objet de l'invention utilise une cible dont la longueur est supérieure ou égale à la longueur de la piste de sorte que la cible est apte à recouvrir l'ensemble de la piste. La couverture progressive de la piste a un effet d'intégration qui produit une évolution de l'amplitude des signaux mesurés aux bornes de chaque enroulement secondaire en fonction de la position de la cible, pouvant, au moins sur une plage, être assimilée à des fonctions sinus et cosinus, quelle que soit la forme de des enroulements, dès lors qu'ils sont périodiques et déphasés d'un quart de période. Cette caractéristique permet de réaliser des capteurs économiques en augmentant les tolérances de fabrication ou d'augmenter la longueur utile d'une piste donnée en réduisant la sensibilité aux effets de bord.  According to a particularly advantageous embodiment using this feature, the device of the invention uses a target whose length is greater than or equal to the length of the track so that the target is able to cover the entire track. The progressive coverage of the track has an integration effect which produces an evolution of the amplitude of the signals measured at the terminals of each secondary winding as a function of the position of the target, being able, at least over a range, to be assimilated to Sine and cosine functions, whatever the form of windings, as long as they are periodic and out of phase by a quarter of a period. This feature allows for cost-effective sensors by increasing manufacturing tolerances or increasing the usable length of a given track by reducing sensitivity to edge effects.
L'invention concerne également un procédé pour la mesure d'une position ou d'un déplacement utilisant un dispositif selon l'un quelconque des modes de réalisation comprenant deux enroulements secondaires exposés ci-avant, comprenant les étapes consistant à :  The invention also relates to a method for measuring a position or displacement using a device according to any of the embodiments comprising two secondary windings as described above, comprising the steps of:
a. mesurer la tension aux bornes d'un premier et d'un deuxième enroulements secondaires,  at. measuring the voltage across a first and a second secondary windings,
b. délivrer une mesure en combinant les amplitudes des tensions ainsi mesurées selon une fonction non linéaire.  b. delivering a measurement by combining the amplitudes of the voltages thus measured according to a non-linear function.
Ce procédé tire avantage des caractéristiques du dispositif, et notamment la compensation des composantes continues sur les deux enroulements secondaires pour améliorer la précision de la mesure. This method takes advantage of the characteristics of the device, and in particular the compensation of the DC components on the two secondary windings for improve the accuracy of the measurement.
Avantageusement, le procédé de mesure utilise un dispositif comprenant deux enroulements secondaires comportant une répétition périodique de boucles selon la même période sur les deux enroulements secondaires, dont les répétitions sont déphasées d'un quart de période et une cible de longueur supérieure à la longueur de la piste, la fonction non linéaire étant l'arc-tangente du rapport des amplitudes des tensions mesurées aux bornes d'un premier et d'un deuxième enroulement secondaires. La présence des boucles de compensation permet de tirer pleinement partie de l'effet d'intégration obtenu par ce type de cible, en améliorant la répétabilité des caractéristiques de ce type de capteur fabriqué en série.  Advantageously, the measurement method uses a device comprising two secondary windings comprising a periodic repetition of loops according to the same period on the two secondary windings, whose repetitions are out of phase by a quarter of a period and a target of length greater than the length of the track, the non-linear function being the arc tangent of the ratio of the amplitudes of the voltages measured at the terminals of a first and a second secondary winding. The presence of compensation loops makes it possible to take full advantage of the integration effect obtained by this type of target, by improving the repeatability of the characteristics of this type of sensor manufactured in series.
L'invention sera maintenant plus précisément décrite dans le cadre de modes de réalisation préférés, nullement limitatifs, et selon les figures 1 à 6, dans lesquelles : The invention will now be more specifically described in the context of preferred embodiments, in no way limiting, and according to FIGS. 1 to 6, in which:
• la figure 1 relative à l'art antérieur, représente un dispositif de mesure de la position d'une cible en vue de dessus, entre deux positions extrêmes de la cible figure 1 B, ainsi que, figure 1C, un diagramme d'évolution de la mesure délivrée par un tel dispositif sur la longueur utile de la cible ; FIG. 1 relating to the prior art shows a device for measuring the position of a target in a view from above, between two extreme positions of the target FIG. 1B, and FIG. 1C an evolution diagram. the measurement delivered by such a device on the useful length of the target;
• la figure 2, également relative à l'art antérieur, montre en vue de dessus un exemple de réalisation d'un capteur comprenant deux enroulements secondaires aptes à délivrer un signal sinusoïdal en fonction de la position longitudinale de la cible ;  FIG. 2, also relating to the prior art, shows in an overhead view an exemplary embodiment of a sensor comprising two secondary windings capable of delivering a sinusoidal signal as a function of the longitudinal position of the target;
• la figure 3 illustre en vue de dessus un mode de réalisation particulier de l'invention dans lequel l'un des enroulements secondaires comporte une boucle de compensation ;  FIG. 3 is a top view of a particular embodiment of the invention in which one of the secondary windings comprises a compensation loop;
• la figure 4 représente en vue de dessus, figures 4A, 4B et 4C, un exemple de réalisation de l'invention comportant deux enroulements secondaires en créneaux dont l'un comporte une boucle de compensation et une cible de longueur supérieure ou égale à celle de la piste :  FIG. 4 is a top view of FIGS. 4A, 4B and 4C, an exemplary embodiment of the invention comprising two crenellated secondary windings, one of which comprises a compensation loop and a target of length greater than or equal to of the track:
- figure 4A lorsque la cible est au début de l'étendue de mesure du capteur,  FIG. 4A when the target is at the beginning of the measurement range of the sensor,
- figure 4B lorsque la cible se trouve sensiblement à la fin de l'étendue de mesure de la piste, et  FIG. 4B when the target is substantially at the end of the measuring range of the track, and
- figure 4C, le résultat observé sur les signaux délivrés par un tel capteur avec et sans boucle de compensation, FIG. 4C, the result observed on the signals delivered by such a sensor with and without compensation loop,
• La figure 5 montre en vue de dessus un exemple de réalisation d'un capteur à piste circulaire apte à mesurer la position angulaire du bord d'attaque d'une cible, la piste comportant deux enroulements secondaires en créneaux comportant chacun une boucle de compensation ; FIG. 5 shows in plan view an exemplary embodiment of a sensor circular track capable of measuring the angular position of the leading edge of a target, the track comprising two secondary windings in slots each comprising a compensation loop;
• la figure 6 présente des exemples de modification du signal délivré par un capteur avec et sans l'adjonction de boucles de compensation :  FIG. 6 shows examples of modification of the signal delivered by a sensor with and without the addition of compensation loops:
- sur la fonction cosinus, figure 6A,  on the cosine function, FIG. 6A,
- sur la fonction sinus, figure 6B et  on the sinus function, FIG. 6B and
- sur la fonction arc-tangente en résultant, figure 6C.  on the resulting arc-tangent function, FIG. 6C.
La figure 3, selon un exemple de réalisation le dispositif objet de l'invention, comporte une piste 350 s'étendant selon un axe longitudinal 1000 correspondant à l'axe sur lequel se projette la coordonnée de position de la cible 200, coordonnée à laquelle la mesure délivrée par le dispositif de mesure est proportionnelle. La piste comprend un enroulement primaire 10, un premier enroulement secondaire 211 comportant une pluralité de boucles selon un motif périodique sinusoïdal et un deuxième enroulement secondaire 212 comportant une pluralité de boucles décrivant également un motif périodique sinusoïdal, déphasé d'un quart de période par rapport aux boucles du premier enroulement secondaire. L'organisation spatiale des boucles et des enroulements fait que lorsque la piste n'est pas couverte par une cible 200, les tensions induites aux bornes des deux enroulements secondaires 211 , 212 sont nulles.  FIG. 3, according to an exemplary embodiment of the device according to the invention, comprises a track 350 extending along a longitudinal axis 1000 corresponding to the axis on which the coordinate of position of the target 200, coordinated with which the measurement delivered by the measuring device is proportional. The track comprises a primary winding 10, a first secondary winding 211 comprising a plurality of loops in a sinusoidal periodic pattern and a second secondary winding 212 having a plurality of loops also describing a sinusoidal periodic pattern, shifted by a quarter of a period relative to to the loops of the first secondary winding. The spatial organization of the loops and windings means that when the track is not covered by a target 200, the voltages induced across the two secondary windings 211, 212 are zero.
Le dispositif comprend en outre des moyens (non représentés) pour alimenter l'enroulement primaire par un courant de tension alternative à haute fréquence, des moyens (non représentés) aptes à mesurer et à démoduler la tension aux bornes des enroulements secondaires 211 , 212 et des moyens de traitement du signal, non représentés, aptes à réaliser des opérations sur les signaux mesurés aux bornes des enroulements secondaires, de sorte à délivrer une mesure proportionnelle à la position relative de la cible sur l'axe longitudinal 1000 de la piste.  The device further comprises means (not shown) for supplying the primary winding with a high frequency AC voltage current, means (not shown) capable of measuring and demodulating the voltage across the secondary windings 211, 212 and signal processing means, not shown, capable of performing operations on the signals measured at the terminals of the secondary windings, so as to deliver a measurement proportional to the relative position of the target on the longitudinal axis 1000 of the track.
La cible 200, de largeur sensiblement égale à celle de la piste 350 et de longueur sensiblement égale à une demi-période du motif décrit par les boucles des enroulements secondaires 211 , 212, est apte à se déplacer dans un plan parallèle à celui de la piste et parallèlement son axe longitudinal 100,0 de sorte à recouvrir, sans contact, une partie de la surface des enroulements secondaires 211 , 212. Ce déplacement s'effectue à une distance sensiblement constante de la piste 350.  The target 200, of width substantially equal to that of the track 350 and of length substantially equal to half a period of the pattern described by the loops of the secondary windings 211, 212, is able to move in a plane parallel to that of the track and parallel to its longitudinal axis 100.0 so as to cover, without contact, a portion of the surface of the secondary windings 211, 212. This movement takes place at a substantially constant distance from the track 350.
Au cours de ce déplacement, chaque enroulement secondaire 211 , 212 délivre, après démodulation de la tension mesurée à ses bornes, un signal qui varie sensible avec le déplacement de la cible 200 comme l'aire de cet enroulement recouverte par la cible 200. Chaque enroulement 210, 211 décrivant des boucles selon un motif sinusoïdal les signaux délivrés sont assimilables à un sinus et à un cosinus dont le rapport fournit une tangente et dont on peut calculer l'arc-tangente pour obtenir une information sensiblement linéaire en fonction de la position de la cible 200 sur la piste 350. Ce traitement fonctionne dès lors que la surface de la piste comportant des enroulements secondaires est recouverte par une surface de cible sensiblement constante, de sorte que les deux enroulements secondaires 21 1 , 212 délivrent des signaux sinus et cosinus. Cette condition est vérifiée sensiblement entre la position A et la position B de la cible 200 de sorte que la plage de mesure utile d'un tel capteur est de l'ordre de la moitié de la longueur de sa piste 350. During this displacement, each secondary winding 211, 212 delivers, after demodulation of the voltage measured at its terminals, a signal that varies significantly with the displacement of the target 200 as the area of this coil covered by the target 200. Each winding 210, 211 describing loops in a sinusoidal pattern the delivered signals are comparable to a sine and a cosine whose ratio provides a tangent and from which the arc tangent can be calculated to obtain substantially linear information as a function of the position of the target 200 on the track 350. This treatment works as soon as the surface of the track having secondary windings is covered by a surface substantially constant target, so that the two secondary windings 21 1, 212 provide sine and cosine signals. This condition is verified substantially between the position A and the position B of the target 200 so that the useful measurement range of such a sensor is of the order of half the length of its track 350.
En théorie, pour un enroulement donné, par exemple le deuxième enroulement 212, les tensions induites dans les deux boucles 2121 , 2122 de cet enroulement en l'absence de cible recouvrant une partie de celui-ci, s'équilibrent de sorte que la tension mesurée aux bornes de ce second enroulement 212 est nulle en l'absence de cible. Si le signal délivré par ce second enroulement au cours du trajet de la cible 200 n'est pas centré, l'adjonction d'une boucle de compensation 310 sur l'une des boucles de cet enroulement permet de compenser cet effet. Un tel décentrage du signal peut être lié à différents aspects constructifs du capteur. Par exemple, les deux enroulements secondaires 211 , 212 peuvent être déposés sur deux faces différentes de la piste 350 de sorte que la distance entre la cible 200 et chacun de ces enroulements secondaires 211 , 212 est différente comme son effet sur le couplage inductif. Le déplacement de la cible peut ne pas être exactement parallèle à la piste 350, ou présenter un défaut de parallélisme par rapport à l'axe longitudinal 1000 de celle-ci. Sans être liée par une quelconque théorie, cette boucle de compensation 310 allonge l'une des boucles 2122 de cet enroulement secondaire 212 de sorte que les tensions induites entre les deux boucles 2121 , 2122 ne s'équilibrent plus exactement en l'absence de cible les recouvrant, ce déséquilibre des tensions compensant le décentrement de signal produit par cet enroulement 212 en fonction du déplacement de la cible 200.  In theory, for a given winding, for example the second winding 212, the voltages induced in the two loops 2121, 2122 of this winding in the absence of a target covering a part of it, are balanced so that the voltage measured at the terminals of this second winding 212 is zero in the absence of a target. If the signal delivered by this second winding during the path of the target 200 is not centered, the addition of a compensation loop 310 on one of the loops of this winding compensates for this effect. Such decentering of the signal can be related to different constructive aspects of the sensor. For example, the two secondary windings 211, 212 may be deposited on two different faces of the track 350 so that the distance between the target 200 and each of these secondary windings 211, 212 is different as its effect on the inductive coupling. The displacement of the target may not be exactly parallel to the track 350, or have a parallelism defect with respect to the longitudinal axis 1000 thereof. Without being bound by any theory, this compensation loop 310 extends one of the loops 2122 of this secondary winding 212 so that the voltages induced between the two loops 2121, 2122 do not balance more accurately in the absence of a target. overlying them, this imbalance of the voltages compensating for the signal shifting produced by this winding 212 as a function of the displacement of the target 200.
Dans la figure 4, selon un mode de réalisation avantageux de l'invention, la cible 400 a une longueur supérieure ou égale à l'étendue de mesure de la piste 450 et recouvre l'intégralité de celle-ci au cours de son trajet. La piste 450 comporte un enroulement primaire 10 et deux enroulements secondaires 411 , 412 décrivant des boucles à motif périodique déphasées spatialement d'un quart de période entre les deux enroulements 41 1 , 412. Les motifs répétitifs décrits par ces boucles peuvent être de forme quelconque, dans cet exemple il s'agit d'un motif en créneaux. En passant de la figure 4A à la figure 4B, dans son trajet selon l'axe longitudinal 1000, la cible 400 recouvre une surface toujours croissante de la piste 450. Selon ce mode de réalisation, figure 4C, le signal 102 démodulé mesuré aux bornes des enroulements secondaires 411 , 412 suit, en fonction du déplacement 101 du bord d'attaque 401 de la cible 400 par rapport à la piste 450, des évolutions 404, 403 assimilables à des fonctions sinus et cosinus, quel que soit le motif périodique décrit par les boucles, et dont le rapport et le calcul de l'arc-tangente fourni une mesure quasi-linéaire de la position du bord d'attaque 401 de la cible 400. Ce phénomène, assimilable à une intégration du signal délivré en fonction de la variation de l'aire de chaque enroulement 411 , 412 couvert par la cible 400, est particulièrement avantageux car il permet d'augmenter la plage de mesure utile du capteur qui avoisine alors la longueur de la piste 450. Cependant, le mode de traitement du signal pour aboutir à la mesure de position, devient particulièrement sensible au décentrement des fonctions sinusoïdales 403, 404 obtenues. L'adjonction d'une boucle de compensation sur au moins un 411 des enroulements secondaires 411 , 412 permet de compenser ce type d'effet et d'obtenir un signal 403' recentré. In FIG. 4, according to an advantageous embodiment of the invention, the target 400 has a length greater than or equal to the measuring range of the track 450 and covers all of it during its journey. The track 450 comprises a primary winding 10 and two secondary windings 411, 412 describing periodically patterned loops phase-shifted spatially by a quarter period between the two windings 41 1, 412. The repetitive patterns described by these loops can be of any shape, in this example it is a crenellated pattern. By moving from FIG. 4A to FIG. 4B, in its path along the longitudinal axis 1000, the target 400 covers an ever increasing surface of the track 450. According to this embodiment, FIG. 4C, the demodulated signal 102 measured at the terminals secondary windings 411, 412 follow, depending on the displacement 101 of the leading edge 401 of the target 400 with respect to the track 450, evolutions 404, 403 assimilable to sinus and cosine functions, whatever the periodic pattern described. by the loops, and whose ratio and calculation of the arc tangent provides a quasi-linear measurement of the position of the leading edge 401 of the target 400. This phenomenon, comparable to an integration of the signal delivered as a function of the variation of the area of each winding 411, 412 covered by the target 400, is particularly advantageous because it makes it possible to increase the useful measurement range of the sensor which is then close to the length of the track 450. However, the mode of treatment nt signal to achieve the position measurement, becomes particularly sensitive to the decentering of the sinusoidal functions 403, 404 obtained. The addition of a compensation loop on at least one 411 of the secondary windings 411, 412 compensates for this type of effect and to obtain a signal 403 'recentered.
Sur la figure 5, selon un autre mode de réalisation de l'invention, la piste 550 peut être de forme circulaire, l'axe longitudinal 5000 étant alors un axe circulaire. Cette configuration permet de mesurer le déplacement du bord d'attaque 501 d'une cible 500 également circulaire lorsque ladite cible se déplace en rotation autour d'un axe 530 correspondant au centre de giration de la piste 550. De la même manière, la piste comprend un enroulement primaire 513 alimenté par un courant de tension alternative à haute fréquence, et deux enroulements secondaires 511 , 512 dont les boucles reproduisent des motifs périodiques déphasés d'un quart de période.  In FIG. 5, according to another embodiment of the invention, the track 550 may be circular in shape, the longitudinal axis 5000 then being a circular axis. This configuration makes it possible to measure the displacement of the leading edge 501 of a target 500 also circular when said target moves in rotation about an axis 530 corresponding to the center of gyration of the track 550. Similarly, the track comprises a primary winding 513 fed by a high-frequency alternating voltage current, and two secondary windings 511, 512 whose loops reproduce period-shifted periodic units of a quarter of a period.
L'homme du métier comprendra que la géométrie des boucles d'enroulement représentées sur les diverses figures n'a d'autre but que d'illustrer le principe et que la géométrie réelle des boucles peut être nettement plus complexe, dès lors qu'il s'agit d'un motif périodique. Avantageusement, les deux enroulements secondaires sont déphasés d'un quart de période.  Those skilled in the art will understand that the geometry of the winding loops shown in the various figures has no other purpose than to illustrate the principle and that the actual geometry of the loops can be much more complex, since This is a periodic pattern. Advantageously, the two secondary windings are phase shifted by a quarter period.
Selon cet exemple de réalisation, figure 5, le capteur mesure le déplacement angulaire Θ du bord d'attaque 501 de la cible 500. La configuration de ce mode de réalisation avec une cible 500 couvrant un secteur angulaire égal ou supérieur à celui couvert par la piste 550 et apte à recouvrir la totalité de l'amplitude de mesure, est équivalente en effet technique au cas de la piste rectiligne 450 présentée supra figure 4. Elle permet d'augmenter la plage de mesure utile par rapport aux capteurs connus de l'art antérieur, ce qui est particulièrement avantageux dans le cas d'un resolver où les possibilités d'extension de la piste 550 sont limitées de par sa forme circulaire. L'invention est aussi particulièrement avantageuse dans ce mode de réalisation où les sources de décentrage du signal, ne serait-ce que par des aspects constructifs du capteur, sont potentiellement plus nombreuses. À titre d'exemples, non exhaustifs, des défauts de circularité de la piste 550 et de la cible 500, de concentricité des deux, de voile de l'un ou de l'autre sont des facteurs susceptibles de créer un décentrage des signaux et coûteux à régler dans une production économique en grande série. Ces défauts sont avantageusement compensés, pour les ramener à un niveau acceptable en fonction de la précision visée, par l'adjonction de boucles de compensation 510, 514 sur l'un des enroulements secondaires ou sur les deux 51 1 , 512. According to this exemplary embodiment, FIG. 5, the sensor measures the angular displacement Θ of the leading edge 501 of the target 500. The configuration of this embodiment with a target 500 covering an angular sector equal to or greater than that covered by the track 550 and able to cover the entire amplitude of measurement, is equivalent technical effect to the case of the straight track 450 shown supra Figure 4. It increases the useful measurement range with respect to known sensors of the prior art, which is particularly advantageous in the case of a resolver where the extension possibilities of the track 550 are limited by its circular shape. The invention is also particularly advantageous in this embodiment where the sources of decentering of the signal, if only by constructive aspects of the sensor, are potentially more numerous. By way of non-exhaustive examples, defects in the circularity of the track 550 and the target 500, the concentricity of the two, the haze of one or the other are factors likely to create a decentering of the signals and expensive to settle in a mass production economy. These defects are advantageously compensated, to bring them back to an acceptable level as a function of the targeted accuracy, by the addition of compensation loops 510, 514 on one of the secondary windings or on both 51 1, 512.
La figure 6 donne un exemple de la modification de la variation des signaux 603, 603', 603", 604, 604' 604" obtenus aux bornes des enroulements secondaires 41 1 , 51 1 , 412, 512 d'un capteur inductif correspondant à différents modes de réalisation de l'invention avec et sans boucle de compensation et du signal 605, 605', 605" calculé à partir de ces signaux en fonction du déplacement 601 d'une cible. Dans cet exemple, la piste comprend deux enroulements secondaires comprenant chacun une répétition périodique de boucles dont la géométrie, combinée à la forme du bord d'attaque de la cible, est apte à produire une variation de la tension aux bornes de l'enroulement suivant une fonction sinusoïdale en fonction de la position 601 de la cible. Les périodes de répétition des boucles des deux enroulements secondaires sont identiques mais déphasées spatialement l'une de l'autre d'un quart de période. Ainsi, l'un des enroulements secondaires produit une variation de l'amplitude 602 de la tension mesurée à ses bornes, suivant une fonction sinus 604, 604', 604", figure 6B, et pour l'autre enroulement, figure 6A, cette amplitude 602 varie selon une fonction cosinus 603, 603', 603".  FIG. 6 gives an example of the modification of the variation of the signals 603, 603 ', 603 ", 604, 604' 604" obtained at the terminals of the secondary windings 41 1, 51 1, 412, 512 of an inductive sensor corresponding to various embodiments of the invention with and without a compensation loop and the signal 605, 605 ', 605 "calculated from these signals as a function of the displacement 601 of a target In this example, the track comprises two secondary windings each comprising a periodic repetition of loops whose geometry, combined with the shape of the leading edge of the target, is capable of producing a variation of the voltage across the winding according to a sinusoidal function as a function of the position 601 of The repetition periods of the loops of the two secondary windings are identical but spatially offset from one another by a quarter of a period, so that one of the secondary windings produces a variation of the ampli study 602 of the voltage measured at its terminals, according to a sine function 604, 604 ', 604 ", FIG. 6B, and for the other winding, FIG. 6A, this amplitude 602 varies according to a cosine function 603, 603', 603" .
La figure 6A représente un exemple d'évolution de l'amplitude du signal mesuré aux bornes d'un enroulement secondaire délivrant une variation d'amplitude 602 en cosinus avec le déplacement 601 de la cible, selon deux exemples de signaux comprenant une composante indépendante du déplacement 603', 603" et après adjonction d'une boucle de compensation sur cet enroulement, courbe 603. La figure 6B représente un exemple d'évolution de l'amplitude du signal aux bornes de l'enroulement secondaire délivrant une variation en sinus 604, 604', 604" de ladite amplitude 602 avec le déplacement 601 de la cible, en présence d'une composante invariable 604', 604" et après l'adjonction d'une boucle de compensation à cet enroulement, courbe 604. La figure 6C montre le résultat après calcul de la fonction arc-tangente, qui délivre la position mesurée 606 de la cible en fonction de sa position 601 sur la piste, à partir du ratio des amplitudes des signaux. Comparées à la fonction arc-tangente 605 correspondant au calcul effectué à partir du rapport des amplitudes 604, 603 des signaux obtenus en présence de boucles de compensation, les évolutions des fonctions 605', 605" calculées à partir des rapports des amplitudes des signaux 603', 604', 603", 604" mesurés aux bornes des enroulements secondaires ne comprenant pas de boucle de compensation, diffèrent de la fonction nominale 605 à la fois en valeur et en pente. Or, dans ces exemples, la composante de décentrement du signal et indépendante de la position de la cible est inférieure à 10 % de l'amplitude de la variation de l'amplitude du signal sur la plage de mesure utile. Il ressort clairement de ces exemples que la présence de boucles de compensation permet d'améliorer significativement la précision du capteur sur toute la plage de mesure. FIG. 6A represents an example of an evolution of the amplitude of the signal measured at the terminals of a secondary winding delivering an amplitude variation 602 in cosine with the displacement 601 of the target, according to two examples of signals comprising a component independent of the displacement 603 ', 603 "and after adding a compensation loop on this winding, curve 603. FIG. 6B shows an example of an evolution of the amplitude of the signal at the terminals of the secondary winding delivering a sinus variation 604 , 604 ', 604 "of said amplitude 602 with the displacement 601 of the target, in the presence of an invariable component 604 ', 604 "and after the addition of a compensation loop to this winding, curve 604. FIG. 6C shows the result after calculation of the arc function. tangent, which delivers the measured position 606 of the target as a function of its position 601 on the track, from the ratio of the amplitudes of the signals Compared to the arc-tangent function 605 corresponding to the calculation made from the ratio of the amplitudes 604, 603 'signals obtained in the presence of compensation loops, the changes of the functions 605', 605 "calculated from the ratios of the amplitudes of the signals 603 ', 604', 603", 604 "measured across the secondary windings not including compensation loop, differ from the nominal function 605 both in value and slope. However, in these examples, the decentering component of the signal and independent of the position of the target is less than 10% of the amplitude of the variation of the amplitude of the signal over the useful measurement range. It is clear from these examples that the presence of compensation loops significantly improves the accuracy of the sensor over the entire measurement range.
La description ci-avant illustre clairement que par ses différentes caractéristiques et leurs avantages, la présente invention atteint les objectifs qu'elle visait. En particulier, elle permet d'améliorer pour un coût réduit la précision des dispositifs de mesure inductifs linéaires, notamment ceux fabriqués en très grande série.  The above description clearly illustrates that by its different features and advantages, the present invention achieves the objectives it intended. In particular, it makes it possible to improve at a reduced cost the accuracy of linear inductive measuring devices, in particular those manufactured in very large series.

Claims

REVENDICATIONS
1. Dispositif de mesure de type inductif de la position selon une direction longitudinale (1000, 5000) d'une cible (200, 400, 500) caractérisé en ce qu'il comprend : 1. Inductive type measuring device of the position in a longitudinal direction (1000, 5000) of a target (200, 400, 500) characterized in that it comprises:
• une piste (350, 450, 550) s'étendant selon un axe longitudinal (1000, 5000) parallèle à la direction de mesure, laquelle piste (350, 450, 550) comprend un enroulement primaire (10, 513) apte à induire un courant électrique dans un enroulement secondaire (21 1 , 212, 411 , 412, 511 , 512) organisé selon une répétition périodique de boucles ; A track (350, 450, 550) extending along a longitudinal axis (1000, 5000) parallel to the measuring direction, which track (350, 450, 550) comprises a primary winding (10, 513) capable of inducing an electric current in a secondary winding (21 1, 212, 411, 412, 511, 512) organized according to a periodic repetition of loops;
• une cible (200, 400, 500) mobile, apte à se déplacer parallèlement à l'axe longitudinal (1000, 5000) de la piste (350, 450, 550) sans contact avec celle- ci et apte à modifier le courant induit par l'enroulement primaire (10, 513) dans l'enroulement secondaire (211 , 212, 411 , 412, 511 , 512) en fonction de sa position (101 , 601) relative par rapport à la piste (350, 450, 550) selon la direction longitudinale (1000, 5000) ;  A target (200, 400, 500) movable, able to move parallel to the longitudinal axis (1000, 5000) of the track (350, 450, 550) without contact therewith and able to modify the induced current by the primary winding (10, 513) in the secondary winding (211, 212, 411, 412, 511, 512) as a function of its relative position (101, 601) with respect to the track (350, 450, 550 ) in the longitudinal direction (1000, 5000);
• l'enroulement secondaire (212, 411 , 511 , 512) comportant en outre une boucle de compensation (310, 410, 510, 514) apte à éliminer une composante indépendante de la position de la cible dans le couplage inductif entre l'enroulement primaire (10, 513) et l'enroulement secondaire (212, 411 , 511 , 512).  The secondary winding (212, 411, 511, 512) further comprising a compensation loop (310, 410, 510, 514) capable of eliminating a component independent of the position of the target in the inductive coupling between the winding primary (10, 513) and the secondary winding (212, 411, 511, 512).
2. Dispositif selon la revendication 1 , caractérisé en ce que l'axe longitudinal (5000) de la piste (550) est un axe circulaire.  2. Device according to claim 1, characterized in that the longitudinal axis (5000) of the track (550) is a circular axis.
3. Dispositif selon la revendication 1 , caractérisé en ce qu'il comprend un deuxième enroulement secondaire (211 , 412, 512) organisé selon une répétition périodique de boucles.  3. Device according to claim 1, characterized in that it comprises a second secondary winding (211, 412, 512) organized according to a periodic repetition of loops.
4. Dispositif selon la revendication 3, caractérisé en ce que le deuxième enroulement secondaire (211 , 412, 512) comprend une boucle de compensation (514) apte à éliminer une composante indépendante de la position de la cible (200, 400, 500) dans le couplage inductif entre l'enroulement primaire (10, 513) et cet enroulement secondaire (211 , 412, 512).  4. Device according to claim 3, characterized in that the second secondary winding (211, 412, 512) comprises a compensation loop (514) capable of eliminating a component independent of the position of the target (200, 400, 500) in the inductive coupling between the primary winding (10, 513) and this secondary winding (211, 412, 512).
5. Dispositif selon la revendication 3, caractérisé en ce que les répétitions périodiques des boucles des deux enroulements secondaires (211 , 212, 41 1 , 412, 511, 5. Device according to claim 3, characterized in that the periodic repetitions of the loops of the two secondary windings (211, 212, 41 1, 412, 511,
512) sont réalisées selon la même période. 512) are carried out according to the same period.
6. Dispositif selon la revendication 5, caractérisé en ce que les répétitions des boucles des deux enroulements secondaires (211 , 212, 412, 511 , 512) sont déphasées d'un quart de période. 6. Device according to claim 5, characterized in that the repetitions of the loops of the two secondary windings (211, 212, 412, 511, 512) are out of phase. a quarter period.
7. Dispositif selon la revendication 6 caractérisé en en ce que la longueur de la cible (400, 500) est supérieure ou égale à la longueur de la piste (450, 550) de sorte que la cible (400, 500) est apte à recouvrir l'ensemble de la piste (450, 550).  7. Device according to claim 6 characterized in that the length of the target (400, 500) is greater than or equal to the length of the track (450, 550) so that the target (400, 500) is adapted to cover the entire runway (450, 550).
8. Procédé pour la mesure d'une position ou d'un déplacement utilisant un dispositif selon l'une quelconque des revendications 3 à 7, caractérisé en ce qu'il comprend les étapes consistant à : 8. A method for measuring a position or displacement using a device according to any one of claims 3 to 7, characterized in that it comprises the steps of:
c. mesurer la tension aux bornes d'un premier (211 , 411 , 51 1 ) et d'un deuxième (212, 412, 512) enroulements secondaires,  vs. measuring the voltage across a first (211, 411, 51 1) and a second (212, 412, 512) secondary windings,
d. délivrer une mesure en combinant les amplitudes (404, 403, 603, 604) des tensions ainsi mesurées selon une fonction non linéaire (605).  d. delivering a measurement by combining the amplitudes (404, 403, 603, 604) of the voltages thus measured according to a non-linear function (605).
9. Procédé selon la revendication 8 utilisant un dispositif selon la revendication 7 caractérisé en ce que la fonction non linéaire est l'arc-tangente (605) du rapport des amplitudes des tensions mesurées aux bornes d'un premier (211 , 411 , 511) et d'un deuxième (212, 412, 512) enroulements secondaires. 9. The method of claim 8 using a device according to claim 7 characterized in that the nonlinear function is arc-tangent (605) of the ratio of the amplitudes of the voltages measured across a first (211, 411, 511). ) and a second (212, 412, 512) secondary windings.
PCT/EP2010/005934 2010-09-10 2010-09-29 Linear position sensor WO2012031616A1 (en)

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FR3031588B1 (en) 2015-01-13 2018-11-16 Hutchinson INDUCTIVE DISPLACEMENT SENSORS
FR3031587B1 (en) 2015-01-13 2018-11-16 Hutchinson INDUCTIVE DISPLACEMENT SENSORS
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