EP3111173A1

EP3111173A1 - Magnetic sensor for determining the relative position between a magnetized target and a measurement system

Info

Publication number: EP3111173A1
Application number: EP15713542.7A
Authority: EP
Inventors: Sébastien Guerin; Harijaona RAKOTOARISON; Mathieu LE NY
Original assignee: Electricfil Automotive SAS
Current assignee: EFI Automotive SA
Priority date: 2014-02-28
Filing date: 2015-02-27
Publication date: 2017-01-04
Also published as: FR3018113B1; US20160349080A1; MX2016011178A; CN106062518A; WO2015128592A1; FR3018113A1

Abstract

The invention relates to a magnetic sensor for determining the position along a displacement trajectory (T), between a target (2) and a measurement system (3) for measuring the amplitude of the magnetic field created or modified by the target. The sensor comprises: - a system for creating a magnetic field according to a direction (M) perpendicular to the displacement trajectory (T) and with an intensity varying according to a parabolic law, - a measurement system (3) comprising at least two measurement elements (3a), (3b) spatially offset from one another and sensitive to the amplitude of the magnetic field along a given direction, - a processing circuit able to carry out a differential processing of the signals delivered by the measurement elements so as to obtain a linear variation signal giving the position of the target along the displacement trajectory.

Description

MAGNETIC SENSOR

TO DETERMINE THE RELATIVE POSITION BETWEEN A MAGNIFYING TARGET AND A MEASURING SYSTEM

The present invention relates to the technical field of magnetic non-contact sensors, adapted to determine the position of a moving part moving along a determined path.

The present invention finds applications that are particularly advantageous, but not exclusively, in the field of motor vehicles with a view to equipping various mobile parts whose position must be known and forming part of, for example, a gearbox, the engine or a clutch. piloted, a power steering, a trim system, etc.

The state of the art has proposed many alternative embodiments of such magnetic non-contact sensors. In general, a magnetic sensor makes it possible to determine, without contact, the relative position, along an angular displacement trajectory, linear or curvilinear, between a target and a system for measuring the magnetic field created or modified by the target. The target or the measuring system is mounted integral with the mobile whose position is to be determined. The target is part of a system for creating a magnetic field along the path of travel. The measuring system is connected to a processing circuit of the signals delivered by the measurement system for delivering a signal depending on the relative position between the target and the measurement system.

According to a first category of solutions described for example in documents US 2001/0038281, US 2004/0164727, the measurement system comprises a single-element sensitive cell adapted to measure the amplitude of the magnetic field. The advantages of such sensors are the simplicity of realization and the insensitivity to the temperature whereas the main disadvantage concerns its sensitivity to variations of airgap and disturbing magnetic fields inducing a significant error of nonlinearity. According to a second category of solutions described for example in documents EP 0 979 988 and FR 2 953 286, the measuring system detects the orientation of the magnetic field by measuring the different components of the magnetic field. The advantage of such sensors is insensitivity to temperature and air gap variations. However, this sensor is sensitive to disturbing magnetic fields and has difficulty in achieving the correct orientation of the magnetic field.

It is also known from US Pat. No. 3,419,798, a magnetic system for detecting the linear displacement between a magnetic target and a magnetic field amplitude measuring system comprising two Hall effect sensors. The magnetic target is in the form of a magnetized blade extending in a parabolic or hyperbolic form. The direction of the magnetic field is parallel to the width of the target considered between its two opposite longitudinal edges.

Thus, this magnet is magnetized in a direction perpendicular to the plane formed by the stroke and the direction of the hall effect sensor. Such an arrangement implies a low value of the magnetic field seen by the sensor, which requires working with a very low air gap. Moreover, the magnetization is obtained by the deformation of the magnet, which induces mechanical stresses in the material, disturbing the magnetization. Finally, the use of pads to deform the magnet and the making of holes in the magnet to fix it induce a disturbance of the magnetic field provided by the magnet so that it is not possible to obtain a distribution. controlled spatial magnetic field.

US Pat. No. 6,323,643 describes a position sensor comprising a magnet fixed to a rotor rotating about an axis of rotation. The magnet has a polarized surface of semi-parabolic shape and located opposite a fixed Hall effect sensor. Such a position sensor is sensitive to external magnetic fields since it comprises a single Hall effect sensor.

The present invention aims to remedy the disadvantages of the state of the art by proposing a magnetic position sensor insensitive to the temperature, air gap variations and magnetic disturbance fields.

To achieve such an objective, the invention aims to use a magnetic signature whose intensity varies according to a parabolic law and to ensure the difference between the magnetic field amplitude measurements considered in at least two points of space.

The sensor according to the invention relates to a magnetic sensor for determining the relative angular or linear position, along a path of movement, between a target and a system for measuring the amplitude of the magnetic field created or modified by the target having an external shape. , the target forming part of a system for creating a variable magnetic field according to at least the displacement trajectory, the measurement system comprising at least two measuring elements spatially offset from one another and sensitive to the amplitude of the magnetic field according to a given direction, this measuring system being connected to a processing circuit of the signals delivered by the measuring system. According to the invention:

the creation system creates a magnetic field with an intensity varying according to a parabolic law, in a direction perpendicular to the trajectory of displacement and traversing the external shape of the target and the gap delimited between the external shape of the target and the system measuring,

- The processing circuit is adapted to perform a differential treatment of the signals delivered by the measuring elements to obtain a linear variation signal giving the position of the target along the path of movement.

The sensor according to the invention further comprises, in combination, one and / or the other of the following additional characteristics:

the creation system creates a magnetic field with an intensity varying according to a parabolic law according to the trajectory of displacement, the processing circuit is able to perform a metric ratio processing of said signals delivered by the measuring elements,

the creation system creates a magnetic field whose direction is perpendicular to a trajectory of linear displacement or rotation, the creation system creates a magnetic field whose direction is perpendicular to a trajectory of displacement carried out according to a surface and in that the measuring system has at least three non-aligned measuring elements,

the creation system creates a magnetic field whose direction is perpendicular to a displacement trajectory combining a rotation and a translation and that the measurement system comprises at least three non-aligned measuring elements,

the creation system creates a magnetic field whose direction is perpendicular to a displacement trajectory combining two rotations and the measurement system comprises at least three non-aligned measuring elements,

the creation system comprises a magnetized target with a constant magnetization intensity and with at least one external shape according to a parabolic law,

the creation system comprises a magnet having a constant magnetization intensity and a ferromagnetic target delimiting with the magnet, an air gap in which the measurement system is placed, the magnet having a direction of magnetization oriented perpendicular to the shape external of the ferromagnetic target which follows a parabolic law, - the creation system comprises a magnetized target having a magnetic field of intensity distributed according to a parabolic law,

the creation system comprises at least one coil and a target making it possible to create a parabolic variation of the intensity of the magnetic field at the level of the measurement system.

Various other characteristics appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the subject of the invention. Figure 1A illustrates a first embodiment of a position sensor according to the invention.

Figure 1B illustrates a second embodiment of a position sensor according to the invention.

Figure 1C illustrates a third embodiment of a position sensor according to the invention.

Figure 1D illustrates a fourth embodiment of a position sensor according to the invention.

Figures 2A and 2B are schematic views of two equivalent mounting examples of a measuring system forming part of the position sensor according to the invention.

Figure 2C illustrates different mounting variants of measuring elements of a measuring system adapted to determine the trajectory of a mobile being established according to a surface.

Figure 3A is a diagram illustrating the parabolic variation of the magnetic field as a function of the stroke of a moving body.

Figure 3B is a diagram illustrating the difference between parabolic shaped signals as a function of the stroke of the mobile.

Figures 4A and 4B are respectively perspective and front views, of an exemplary embodiment of a linear position sensor which comprises a convex shaped target.

Figures 4C and 4D show an embodiment of a linear position sensor implementing a concave target.

Figures 5A and 5B are respectively perspective and top views of an exemplary embodiment of a radial position sensor.

Figures 6A and 6B respectively illustrate views in perspective and from above, of an exemplary embodiment of a radial position sensor.

Figures 7A to 7D are respectively perspective views, side, front and top, of a position sensor for a mobile moving in a plane. FIGS. 8A to 8D are respectively perspective views, side views in a linear displacement, of face along the axis of rotation and from above, of an exemplary embodiment of a position sensor for a mobile having a trajectory of linear and rotational movement.

Figures 9A to 9D are respectively perspective views, front, side and top, a position sensor for a mobile having a linear trajectory and rotation about an axis.

FIGS. 10A to 10D are respectively perspective, side, front and top views of an exemplary embodiment of a sensor for terminating the path of movement in two rotations.

As is apparent from the drawings, the subject of the invention relates to a magnetic sensor 1 making it possible to determine, without contact, the position of a mobile moving along a trajectory T which can be angular, linear or curvilinear, as shown in the various embodiments illustrated in the drawings. The magnetic sensor 1 comprises a target 2 and a system 3 for measuring a magnetic field created or modified by the target.

According to a first embodiment, the target 2 is part or is integral with the mobile whose position is to be determined while the measurement system 3 is fixed relative to the target which is movable. According to a second embodiment, the measuring system 3 is part or is mounted integral with the mobile whose position is to be determined while the target 2 is fixed relative to the measuring system 3 which is movable. The sensor 1 according to the invention thus makes it possible to determine the relative position between the target 2 and the system 3 for measuring the magnetic field. For the sake of simplicity and clarity, it is considered in the remainder of the description that the sensor is adapted to determine the position of the mobile corresponding either to the mobile target 2 with respect to the measurement system 3 which remains fixed or to the system. measurement 3 mobile relative to the target 2 fixed.

Conventionally, the target 2 and measurement system 3 are positioned to delimit an air gap E traversed by the magnetic field. For this purpose, the target 2 comprises a shape or an outer surface 2a delimiting a portion of the gap and directed towards the measuring system 3.

The target 2 is part of a system for creating a magnetic field 4. According to a characteristic of the invention, the creation system 4 creates a magnetic field in a direction M perpendicular to the trajectory of displacement T and with an intensity varying according to a parabolic law. The direction M of the magnetic field passes through the outer shape 2a of the target 2 and also passes through the gap E defined between the target 2 and the measurement system 3. This creation system 4 can be realized in different ways.

In the example illustrated in FIG. 1A, the creation system 4 comprises a magnetized target 2 made by a magnet delivering a magnetic field having a magnetization direction M and an amplitude or intensity varying according to a parabolic law in at least one direction M crossing the outer shape 2a of the target and the gap E. The target 2 thus delivers a magnetic field of intensity distributed according to a parabolic law in at least one direction. This parabolic variation of the intensity of the magnetic field is created to be detected or measured by the measurement system 3.

In the example illustrated in FIG. 1B, the creation system 4 comprises a magnetized target 2 made by a magnet having an outer shape 2a according to a parabolic law. This magnet has a constant magnetization intensity with a magnetization direction M passing through the external shape 2a of the target and the gap E. The target 2 thus delivers a magnetic field of intensity distributed according to a parabolic law according to at least one direction. This parabolic variation of the intensity of the magnetic field is created to be detected or measured by the measurement system 3.

In the example illustrated in FIG. 1C, the creation system 4 comprises a magnet 4a and a ferromagnetic target 2. It should be noted that the magnet 4a is considered to be part of the measuring system 3. The ferromagnetic target 2 has for example an outer shape 2a according to a parabolic law. The magnet 4a has a constant magnetization intensity with a direction of magnetization M passing through the external shape 2a of the ferromagnetic part and the gap E. The target 2 thus delivers a magnetic field of intensity distributed according to a parabolic law according to at least one direction. This parabolic variation of the intensity of the magnetic field is created to be detected or measured by the measurement system 3.

In the example illustrated in FIG. 1D, the creation system 4 comprises at least one coil 4b and a ferromagnetic or conductive target 2. It should be noted that the coil 4b is considered to be part of the measurement system 3. The target 2 has for example an outer shape 2a following a parabolic law. The coil 4b generates a constant or time-varying magnetic field in a direction M crossing the outer shape 2a of the ferromagnetic part and the gap E. The target 2 thus delivers a magnetic field of intensity distributed according to a parabolic law according to least one direction. This parabolic variation of the intensity of the magnetic field is created to be detected or measured by the measurement system 3.

In the examples illustrated in FIGS. 1C and 1D, the parabolic variation of the intensity of the magnetic field according to the stroke of the mobile is obtained by the parabolic form of the target 2. Of course, this parabolic variation can be obtained differently and depends on the nature of the different materials used by the target 2.

Thus, the creation system 4 makes it possible to obtain, according to a measurement direction x, a parabolic distribution of the magnetic field B such that:

B (x) = ax ² + bx + c.

According to an advantageous variant of embodiment, the creation system 4 creates a magnetic field with an intensity varying according to a parabolic law along the path of displacement T. Thus, the measurement direction x corresponds to the trajectory of displacement T. Of course, as this will be understood in the following description, the measurement direction x can be shifted with respect to the displacement path T. In this case, the measurement system 3 performs the calculations to determine the position of the mobile relative to the path of movement.

Of course, the distribution of the magnetic field created by the system 4 depends on the nature of the trajectory of the mobile. In the example above illustrated in FIGS. 1A to 1D, the parabolic magnetic field varies along a direction making it possible to determine the trajectory of the mobile moving in a linear or curved trajectory.

In the case where the trajectory of the mobile is established on a surface such as flat, cylindrical or spherical for example, then the creation system 4 creates a parabolic magnetic field distributed according to the moving surface T of the mobile. Thus, the creation system 4 makes it possible to obtain a parabolic distribution of the induction B on the displacement surface x, y such that:

B (xy) = ax ² + by ² + cxy + dy + ex + f.

The amplitude of the magnetic field whose intensity varies according to a parabolic law is measured by the measuring system 3. This measurement system 3 comprises at least two measuring elements 3a, 3b, 3c ... spatially offset between them. Each measuring element 3a, 3b, 3c ... is sensitive to the amplitude of the magnetic field in a given direction. For example, these measurement elements are Hall effect cells, magnetoresistive effect cells (AMR, GMR, TMR) or detection coils.

According to a first embodiment, the measuring elements 3a, 3b, 3c, ... are spatially offset from each other in the direction of displacement T as illustrated in FIG. 2A. According to this example, the measuring elements 3a, 3b, 3c, ... are spatially offset in a direction perpendicular to the direction of magnetization M. According to a second embodiment, the measuring elements 3a, 3b, 3c,. .. are spatially offset from each other in a direction perpendicular to the direction of travel T as shown in FIG. 2B. According to this example, the measuring elements 3a, 3b, 3c, ... are spatially offset in a direction parallel to the direction of magnetization M. The mounting of the measuring elements 3a, 3b, 3c, ... according to these two embodiments makes it possible to obtain equivalent measurements of the amplitude of the magnetic field.

The measuring system 3 comprises at least two measuring elements 3a, 3b, 3c, ... for determining the position of the moving body having a displacement path T in one direction. In the case where the trajectory of the mobile is established on a surface then the measuring system 3 comprises at least three measuring elements and for example four or five measuring elements 3a, 3b, 3c, 3d, 3e (FIG 2C). spatially shifted to determine the position of the mobile. The number and the positioning of the measuring elements 3a, 3b, 3c, 3d, 3e are chosen and adapted as a function of the trajectory of the mobile. Thus, in the case where the path of the mobile is established in two directions x, y of a plane then it is advantageous to position at least 2 measuring elements in each direction.

As can be seen from FIG. 3A, each measuring element 3a, 3b, 3c, ... thus delivers an output signal Sa, Sb, Se, ... having a parabolic shape which is a function of the relative position of the measuring system 3 with respect to mobile, along the path of travel T.

The measurement system 3 is connected to a processing circuit, not shown, of the signals delivered by the measuring elements 3a, 3b, 3c, .... According to the invention, the processing circuit is adapted to perform a differential treatment of the signals delivered by the measuring elements in order to obtain a signal S of linear variation giving the position x of the moving body along the path of displacement. As is clear from FIG. 3B, the difference S between parabolic shaped signals gives a linear function as a function of the stroke of the mobile.

The sensor 1 according to the invention thus makes it possible to obtain a linearity of the output signal giving the position of the mobile over the entire path of travel, with the advantage that such an output signal is insensitive to magnetic disturbing fields.

According to an advantageous variant embodiment, the processing circuit is able to perform a metric ratio processing of the signals Sa, Sb, Se, ... delivered by the measuring elements. In other words, the circuit of processing is intended to ensure the difference of two measurement signals divided by the sum of these two measurement signals or by another measurement signal. Thus, the output signal S is no longer a simple differential signal but a ratio between a difference of two measurements and their sum or another measurement. Thus, the output signal S can be expressed as follows:

S = (a.Sa - b.Sb) / (c.Sa + d.Sb) or S = (a.Sa - b.Sb) / c.Sc, where a, b, c and d are constants.

According to this variant, the proportional variation of the magnetic field due to the variation of temperature or gap is thus compensated for by the use of such a metric ratio output signal.

The examples which follow describe various alternative embodiments of the sensor according to the invention as a function of various trajectories of movement of the mobile. In the following drawings, the parabolic distribution of the magnetic field is obtained by the outer shape 2a of a magnetic target 2 having a magnetization direction M, as described in relation to FIG. 1B. Such a choice makes it possible to visualize the shape of the distribution of the magnetic field through the external shape 2 a of the magnetic target. Of course, these different embodiments of the sensor according to the invention may comprise a creation system 4 according to FIGS. 1A, 1C or 1D.

In the example illustrated in FIGS. 4A-4B and 4C-4D, the displacement trajectory T is linear so that the creation system 4 creates a parabolic magnetic field whose magnetization direction M is perpendicular to a linear trajectory T. The creation system 4 comprises a target 2 having in the direction T and depending on the stroke of the mobile, a parabolic outer shape 2a in front of which is positioned the measuring system 3. In the example illustrated in FIGS. 4A-4B, an exterior parabolic form 2a of the target 2 is convex whereas in the example illustrated in FIGS. 4C-4D, the parabolic outer shape of the target 2 is concave.

In the example illustrated in FIGS. 5A-5B, the displacement path T is curved and in particular along a circular segment around an axis O of so that the creation system 4 creates a magnetic field of parabolic shape whose magnetization direction M is perpendicular to a circular or rotational trajectory T. The creation system 4 comprises a target 2 having in the direction T and as a function of the race of the mobile, a parabolic external form 2a in front of which is positioned the measuring system 3

It should be noted that in the example illustrated in FIGS. 5A-5B, the parabolic outer shape 2a of the target 2 is made axially, that is to say along the axis O, while in the example illustrated in FIGS. 6A-6B, the parabolic outer shape 2a of the target 2 is made radially. According to this example, the parabolic external shape 2a is located between the axis of rotation O and the measuring system 3.

In the examples illustrated in FIGS. 5A-5B and 6a-6B, the target 2 has a convex parabolic outer shape 2a but it is clear that the parabolic outer shape 2a can be concave.

In the example illustrated in FIGS. 7A to 7D, the displacement path T is performed along a surface that is an x, y plane. According to this example, the creation system 4 creates a parabolic magnetic field whose magnetization direction M is perpendicular to the displacement path T, that is to say on the x, y plane. Such a creation system 4 makes it possible to obtain a parabolic distribution of the magnetic field on a measurement plane x, y. The creation system 4 comprises a target 2 having in the plane x, y and as a function of the stroke of the mobile, an outer parabolic form 2a in front of which is positioned the measuring system 3. The parabolic external form 2a of the target 2 results from the combination of parabolic forms established along the x and y directions. In the example illustrated in FIGS. 7A to 7D, the parabolic outer shape 2a of the target 2 is convex but it is clear that the parabolic outer shape 2a of the target 2 can be concave. According to this exemplary embodiment illustrated in FIGS. 7A to 7D, the measurement system comprises at least three non-aligned measuring elements, as described in FIG. 2C. In the example illustrated in FIGS. 8A to 8D, the displacement trajectory T is performed according to a surface defined by a rotation at an angulation Θ of center O and by a linear displacement x radial with respect to the angular displacement Θ. According to this example, the creation system 4 creates a parabolic magnetic field whose magnetization direction M is perpendicular to the displacement trajectory T, that is to say to the surface x, Θ. The creation system 4 comprises a target 2 having, according to the surface x, Θ and as a function of the stroke of the mobile, an outer parabolic form 2a in front of which the measurement system 3 is positioned. The parabolic external form 2a of the target 2 which is realized axially results from the combination of the parabolic forms being established according to the directions x and Θ. In the example illustrated in FIGS. 8A to 8D, the parabolic outer shape 2a of the target 2 is convex, but it is clear that the parabolic outer shape 2a of the target 2 can be concave. According to this exemplary embodiment illustrated in FIGS. 8A to 8D, the measurement system comprises at least three non-aligned measuring elements, as described in FIG. 2C.

Figs. 9A to 9D illustrate another exemplary embodiment in which the displacement trajectory T is carried out according to a surface defined by a rotation Θ around a center O and by a linear direction x which is axial, that is to say parallel to the axis O. According to this example, the creation system 4 creates a parabolic magnetic field whose magnetization direction M is perpendicular to the displacement path T, ie to the surface x, Θ. The creation system 4 comprises a target 2 having, according to the surface x Θ, and according to the stroke of the mobile, an outer parabolic form 2a in front of which the measurement system 3 is positioned. The parabolic external form 2a of the target 2 results from the combination of parabolic forms established in the directions x and Θ. In the example illustrated in FIGS. 9A to 9D, the parabolic outer shape 2a of the target 2 is convex but it is clear that the parabolic outer shape 2a of the target 2 can be concave. According to this exemplary embodiment illustrated in FIGS. 9A to 9D, the measuring system has at least three non-aligned measuring elements, as described in FIG. 2C.

Figs. 10A to 10D illustrate another exemplary embodiment in which the displacement trajectory T is performed according to a surface defined by the combination of a first rotation Θ1 and a second rotation Θ2. According to this example, the creation system 4 creates a parabolic magnetic field whose magnetization direction M is perpendicular to the displacement trajectory T, ie to the spherical surface Θ1, Θ2. The creation system 4 comprises a target 2 having, according to the surface Θ1, Θ2 and as a function of the stroke of the mobile, an outer parabolic form 2a in front of which the measuring system 3 is positioned. The parabolic external form 2a of the target 2 results from the combination of parabolic forms established in directions Θ1 and Θ2. In the example illustrated in FIGS. 10A to 10D, the parabolic outer shape 2a of the target 2 is convex but it is clear that the parabolic outer shape 2a of the target 2 can be concave. According to this exemplary embodiment illustrated in FIGS. 10A to 10D, the measurement system comprises at least three non-aligned measuring elements, as described in FIG. 2C.

The invention is not limited to the examples described and shown because various modifications can be made without departing from its scope.

Claims

1 - Magnetic sensor for determining the relative angular or linear position, according to a displacement trajectory (T), between a target (2) and a measurement system (3) of the amplitude of the magnetic field created or modified by the target ( 2) having an external shape (2a), the target (2) forming part of a system (4) for creating a variable magnetic field according to at least the displacement path, the measurement system comprising at least two elements of measuring (3a, (3b, 3c, ...) spatially offset from one another and sensitive to the amplitude of the magnetic field in a given direction, this measuring system being connected to a circuit for processing the signals delivered by the measurement system characterized in that

the creation system (4) creates a magnetic field with an intensity varying according to a parabolic law, in a direction (M) perpendicular to the trajectory of displacement (T) and passing through the external form (2a) of the target and the air gap (E) delimited between the outer shape of the target and the measuring system (3),

2 - Magnetic sensor according to claim 1, characterized in that the creation system (4) creates a magnetic field with an intensity varying according to a parabolic law along the path of displacement (T).

3 - magnetic sensor according to claim 1, characterized in that the processing circuit is capable of performing a metric ratio processing said signals delivered by the measuring elements (3a, 3b, 3c, ...) ·

4 - Magnetic sensor according to one of claims 1 to 3, characterized in that the creation system (4) creates a magnetic field whose direction (M) is perpendicular to a path of travel (T) linear or rotation.

5 - magnetic sensor according to one of claims 1 to 3, characterized in that the creation system (4) creates a magnetic field whose direction (M) is perpendicular to a path of displacement (T) carried out along a surface and in that the measuring system (3) comprises at least three non-aligned measuring elements (3a, 3b, 3c, ...).

6 - Magnetic sensor according to one of claims 1 to 3, characterized in that the creation system (4) creates a magnetic field whose direction is perpendicular to a displacement path (T) combining a rotation and a translation and in that the measuring system (3) comprises at least three non-aligned measuring elements (3a, 3b, 3c, ...).

7 - Magnetic sensor according to claims 1 or 2, characterized in that the creation system (4) creates a magnetic field whose direction (M) is perpendicular to a displacement path (T) combining two rotations and in that the measuring system (3) has at least three non-aligned measuring elements.

8 - Magnetic sensor according to one of claims 1 to 7, characterized in that the creation system (4) comprises a magnetized target (2) with a constant magnetization intensity and with at least one external shape following a parabolic law .

9 - magnetic sensor according to one of claims 1 to 7, characterized in that the creation system (4) comprises a magnet (4a) having a constant magnetization intensity and a ferromagnetic target (2) delimiting with the magnet, an air gap in which the measuring system is placed, the magnet (4a) having a magnetization direction (M) oriented perpendicular to the outer shape of the ferromagnetic target following a parabolic law.

10 - magnetic sensor according to one of claims 1 to 7, characterized in that the creation system (4) comprises a magnetized target (2) having a magnetic field intensity distributed according to a parabolic law.

11 - Magnetic sensor according to one of claims 1 to 7, characterized in that the creation system (4) comprises at least one coil (4b) and a target (2) for creating a parabolic variation of the intensity of the magnetic field at the measuring system (3).