High-precision angular or linear non-contact magnetic position sensor

Abstract

The invention relates to an angular or linear non-contact magnetic position sensor (C) comprising a permanent magnet (A) generating a non-linearly varying magnetic field and at least a first pair of probes associated with the permanent magnet (A), each probe being able to measure at least two field components at the same point. Processing circuitry is connected to the first pair of probes and is configured to measure with at least some of the measurements supplied by the first pair of probes and to deliver a position signal representative of the absolute position of the permanent magnet (A).

Description

Field of the Invention

[0001] The present invention relates to the field of non - contact magnetic and / or electromagnetic position sensors for precisely measuring absolute angles or linear positions. Such sensors enable highly accurate detection of angular positions or linear displacements with a precision of approximately 0.1% of the total travel or < 0.5° for the detection of a complete rotation. Such systems are robust to interference and highly accurate, especially for the automotive and robotics industries. Background Art

[0002] In the prior art, document EP1083406 describes a rotary sensor composed of an annular magnet and two magneto - sensitive sensing elements that measure the radial component of the field generated by a radially magnetized annular magnet. The two magneto - sensitive elements are placed orthogonally and generate two sine signals that enable the detection of the angular position of the rotating magnet by implementing the arctangent function (Atan) of these two signals.

[0003] The drawback of this solution is its sensitivity to the placement of the magneto - sensitive sensing elements for calculating the exact angular value. This solution is also sensitive to any external field. In fact, any stray field having a component measurable by at least one of the two magneto - sensitive elements causes significant non - linear errors.

[0004] Document US7741839 is also known, which presents the principle of a rotary sensor including an annular magnet and two magneto - sensitive sensing elements that measure two orthogonal components of the field generated by the annular magnet at the same point. The two elements generate two sine signals that also enable the detection of the angular position of the rotating magnet by implementing the Atan function of these two signals.

[0005] The accuracy of the detected signals is not satisfactory, limited by significantly different signal amplitudes, leading to incorrect angular position calculations. This solution is also sensitive to any external field.

[0006] Document US7030608 describes some configurations for achieving equality between field components, but the influence is usually very limited and requires a large footprint. Moreover, the problem of sensitivity to any external field is not solved, so this solution can only be considered very insufficient for many applications.

[0007] To improve accuracy, document FR2893410 proposes applying a compensation coefficient (gain) to the ratio of the signals delivered by magneto - sensitive sensing elements located at the same point, which ratio is equal to the ratio of the maximum amplitudes of the measured orthogonal field components. This improves signal non - linearity, but this configuration is still limited to the case of a radially magnetized annular magnet.

[0008] Document EP1989505 describes a linear or rotary transducer, characterized in that the magnetization of the magnet is linearly variable. Similarly, by applying a scaling factor (gain), the linear or angular displacement of the magnet relative to the probe can be determined. However, again, the accuracy is still insufficient here, especially in cases where the magnetization harmonics of the magnet are significant, or if the magnet contains inhomogeneities.

[0009] Document FR2965347 reports a case-by-case definition of the gain value, via a large number of tests or calculations, to define a gain value different from the simple ratio of the maximum amplitude of the component. This solution improves the measurement accuracy, but the setup (test bench, simulation) is still very complex and limited to certain configurations.

[0010] The disadvantage of the latter solutions is their sensitivity to any external field.

[0011] Document FR2923903 describes an angular or linear sensor that includes a magnet whose magnetization direction varies linearly with displacement, using 2 sets of probes placed orthogonally, each probe including a pair of magneto-sensitive sensing elements for measuring orthogonal field components. By combining these different field components to obtain two signals with equal orthogonal intensities, an angular measurement that is insensitive to the external field under certain conditions can be obtained. However, the angular accuracy of the sensor remains moderate. The same principle also applies to linear transducers.

[0012] Document WO2009 / 101270 extends the above principle and introduces a third set of magneto-sensitive sensing elements and a fourth set of magneto-sensitive sensing elements, which are "wisely" offset from the first and second sets and are positioned between them in the same way as the first and second sets. By combining the signals from these 4 sets of magneto-sensitive sensing elements, an angular measurement that is insensitive to the external field under certain conditions can be obtained, and the accuracy of the sensor is improved (at least over a mechanical half-turn, i.e., 180°) by correcting the magnetization error related to the magnet geometry (especially by compensating for magnetization harmonic 3). Considering the number of elements involved (4 separate probes), this solution is still highly sensitive to probe positioning errors and is still too imprecise, with a non-linearity of + / -0.1% over the 180° angular range, i.e., the accuracy over this angular range is at best + / -0.18°. It is still too imprecise to be applied to certain automotive and robotic applications.

[0013] Document EP2711663 describes a sensor with two tracks and at least 2 probes, achieving very high angular accuracy by combining the global detection from the first track and the finer measurements from the second multi-pole track. However, this solution may indeed require a high overall detection accuracy by using additional probes (a total of 4) on this sensor 1. The disadvantage of this solution is its sensitivity to external fields and its susceptibility to errors in the positioning of the probes and the two magnetic tracks.

[0014] Also known in the prior art is document FR3118804, which provides a simple angular or linear displacement measuring device that uses (at least) one magneto-sensitive sensing element capable of measuring at least two field components and a magnetized magnet, the magnetization distribution of which includes a combination of at least two periodic contributions, enabling the simultaneous calculation of the global position in one (or more) revolutions and the more precise local position of the displacement value.

[0015] Some solutions of the prior art have the disadvantage of their sensitivity to external magnetic fields.

[0016] Shielding the transducer is always possible, but this adds parts and significantly increases the manufacturing cost as well as the overall size of the transducer.

[0017] Object of the Invention

[0018] The present invention proposes to at least partially solve the above problems by exploiting the principle disclosed in document FR3118804. In particular, the present invention facilitates the calculation of the global position and the local position. In particular, the present invention enables easy implementation of accurate angular (or linear) position measurement and can be configured to be insensitive to external fields. Summary of the Invention

[0019] To achieve this object, the object of the present invention proposes an angular or linear non-contact magnetic position sensor, which comprises:

[0020] · A permanent magnet that generates a magnetic field that varies non-linearly in the moving direction, the variation including a combination of at least one first quasi-periodic signal and at least one second quasi-periodic signal in various field components, the first quasi-periodic signal being referred to as the "carried signal", the second quasi-periodic signal being referred to as the "carrier signal", and the first signal and the second signal being different from each other,

[0021] · At least one first pair of probes, which includes a first main probe and a first sub-probe, the first pair of probes being associated with the permanent magnet, and each probe being capable of measuring at least two field components at a single point; and

[0022] · A processing circuit, which is connected to the probe and is configured to utilize at least some of the measurements provided by the probe and deliver a position signal representing the absolute position of the permanent magnet.

[0023] According to the present invention, two probes in the first pair of probes are positioned relative to each other such that a first quasi-periodic signal representing the global position and a second quasi-periodic signal representing the local position can be isolated by differential combination of field component measurements.

[0024] According to other advantageous non-limiting features of the present invention (individually or according to any technically feasible combination):

[0025] - The magnetic position sensor includes a second pair of probes, which includes a second main probe and a second secondary probe. The second pair of probes is associated with the permanent magnet, and each probe in the second pair of probes is capable of measuring at least two field components at the same point. The two pairs of probes are positioned relative to each other to obtain orthogonal matching of the signals obtained by differential combination;

[0026] - The processing circuit establishes:

[0027] · Measuring the global position of the sensor by combining field components according to the following formula: Atan2((Br1 + Bt3) + (Br2 + Bt4); gain * ((Br3 - Bt1) + (Br4 - Bt2))) or

[0028] · Measuring the local position of the sensor by combining field components according to the following formula: Atan2((Br3 - Bt1) - (Br4 - Bt2); gain * (Bz1 - Bz2)),

[0029] where Bri, Bti, and Bzi respectively represent the radial field, tangential field, and axial field measured by the probe indexed by i, and where the gain is a selected quantity to minimize the angular error calculated according to the offset of the sensor;

[0030] - The processing circuit establishes: Measuring the local position of the sensor by combining field components according to the following formula: Atan2((Bz3 - Bt1) - (Bz4 - Bt2); gain * ((Bz1 + Bt3) - (Bz2 + Bt4))), where Bri, Bti, and Bzi respectively represent the radial field, tangential field, and axial field measured by the probe indexed by i, and where the gain is a selected quantity to minimize the angular error calculated according to the offset of the sensor;

[0031] - The processing circuit simultaneously establishes global position measurement and / or local position measurement on different faces of the permanent magnet;

[0032] - The permanent magnet is a multi-pole magnet or a magnet assembly or an equivalent machined magnet.

[0033] - The permanent magnet is composed of a set of current loops;

[0034] - The permanent magnet is composed of all or part of the rotor of an electric motor, a generator, an actuator, a gear reducer, a coupling, a gearbox or an oscillator;

[0035] - Each probe includes a plurality of magnetosensitive elements selected from the list consisting of Hall probes, magnetoresistive elements, eddy current elements and detection coils;

[0036] - The permanent magnet has the shape of a disc, a ring or a cylinder, and the probes in at least one pair of probes are arranged around the perimeter of the magnet;

[0037] - The probes in at least one pair of probes are separated by a first angular value corresponding to a half cycle of the carrier signal;

[0038] - The probes in the first pair of probes and the probes in the second pair of probes are separated from each other by a second angular value, which is substantially equal to a quarter cycle of the carrier signal;

[0039] - The first angular value and / or the second angular value is adjustable;

[0040] - The processing circuit is configured to correct the calculated angular value using an angular compensation factor;

[0041] - The correction of the calculated angular value is based on trigonometric functions;

[0042] - The processing circuit is configured to combine the analog detection and digital detection of field components.

[0043] According to another aspect, the present invention proposes to use a non-contact magnetic position sensor as defined above to measure added values on a complex system, including force, torque, acceleration, braking, phase shift, overall speed, direction of movement, distance, number of revolutions, inertia, imbalance, vibration, noise, harmonic content, temperature, pressure, current, voltage, current, frequency, information encoding. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features and advantages of the present invention will become apparent from the following detailed description of the present invention with reference to the accompanying drawings, in which:

[0045] Figure 1

[0046] Figure 1 shows the structure of a rotary encoder in a configuration conforming to the present invention;

[0047] Figure 2

[0048] Figure 2 ​​​​​​shows the evolution curves of the field components measured by the punctual probes of the sensor according to the invention;

[0049] Figure 3 Figure 3 shows the evolution curves of the radial field components measured by the first pair of probes phase-shifted by the first selected angular value, and the added combination of these measurements;

[0050] Figure 4 Figure 4 shows the evolution curves of the radial field components measured by two pairs of probes arranged relative to each other in a configuration according to the invention, for the purpose of calculating the global angular position;

[0051] Figure 5

[0052] Figure 5 shows the evolution curves of the global angular values obtained by combining the radial components measured by four probes arranged relative to each other in a configuration according to the invention;

[0053] Figure 6

[0054] Figure 7

[0055] Figure 6 and Figure 7 respectively show the combination of the tangential and axial components of the field obtained by combining the measurements provided by four probes arranged relative to each other in a configuration according to the invention;

[0056] Figure 8

[0057] Figure 8 shows the evolution curves of the radial field components measured by two pairs of probes arranged relative to each other in a configuration according to the invention, for the purpose of calculating the local angular position;

[0058] Figure 9

[0059] Figure 9 shows the evolution curves of the local angular values obtained by combining the radial components measured by 4 probes arranged relative to each other in a configuration according to the invention;

[0060] Figure 10

[0061] Figure 10 shows the evolution curves of the field components measured by two pairs of probes arranged relative to each other in a configuration according to the invention, the measurements being combined with each other to be less sensitive to the external field in the calculation of the global angular position; ​​​​​​​​​​​​​​​​​​​​

[0062] Figure 11

[0063] Figure 11 shows the result of the angular position calculation provided by a sensor according to the invention, which implements the combination Figure 10 ;

[0064] Figure 12

[0065] Figure 12 shows the evolution curve of the field components measured by two pairs of probes arranged relative to each other in a configuration according to the invention, the measurements being combined with each other to be less sensitive to the external field in the calculation of the local angular position;

[0066] Figure 13

[0067] Figure 13 shows the result of the angular position calculation provided by a sensor according to the invention, which implements the combination Figure 12 ;

[0068] Figure 14

[0069] Figure 14 shows the evolution curve of the field components measured by two pairs of probes arranged relative to each other in a configuration according to the invention, the measurements being combined with each other according to an alternative combination of the combination shown in Figure 12 ;

[0070] Figure 15

[0071] Figure 15 shows the result of the angular position calculation provided by a sensor according to the invention, which implements the combination Figure 14 ;

[0072] Figure 16a

[0073] Figure 16b

[0074] Figure 17a

[0075] Figure 17b

[0076] Figure 18a

[0077] Figure 18b

[0078] Figure 16a , Figure 16b , Figure 17a , Figure 17b ​​​​​​​​​​​​​​​​​​​​​​​​​​​, Figure 18a , Figure 18b shows the influence of an external magnetic field on the angular error;

[0079] Figure 19

[0080] Figure 19 shows sensor C in a linear configuration according to the present invention;

[0081] Figure 20

[0082] Figure 21

[0083] Figure 20 and Figure 21 shows the result of the angular position calculation provided by a sensor according to the present invention, which operates in a degraded mode using only a pair of probes;

[0084] Figure 22

[0085] Figure 22 shows the structure of a rotary encoder in another configuration according to the present invention. Detailed Description

[0086] Figure 1 shows the structure of a magnetic position sensor C in one embodiment. The magnetic flux generated by the disc-shaped permanent magnet A is collected at its periphery by at least four groups of sensing elements 1-4 (or magnetic sensors) positioned radially or axially, which do not contact the magnet. The permanent magnet can have any shape other than the disc shape of magnet A shown Figure 1 , in particular an annular or cylindrical shape.

[0087] Each group of sensing elements measures at least two components of the magnetic induction at the same point, if necessary via a flux collector that defines the air gap in which the sensing elements 1-4 are placed. The magnetosensitive elements can include, for example, Hall probes, magnetoresistive elements, eddy current elements, and detection coils. As is well known, each group of magnetosensitive elements can be integrated into a housing to form a magnetic probe capable of detecting two or three field components. For the sake of simplicity of expression, in the remainder of this specification, "probe" will refer to a group of magnetosensitive elements capable of detecting two or three field components at almost any given moment. However, this designation in no way limits the implementation of the principles of the present invention, which can involve placing several groups of magnetosensitive elements in the same housing to detect field components at multiple points.

[0088] Therefore, Figure 1 ​​​​​​​​​​​The magnetic position sensor C shown has four probes 1 - 4, including on the one hand a first main probe 1 and a second main probe 2, and on the other hand a first secondary probe 3 and a second secondary probe 4. The first main probe 1 and the first secondary probe 2 form a first pair of probes 1, 2 which are angularly out of phase with each other at a first separation angle θ. The second main probe 3 and the second secondary probe 4 form a second pair of probes 3, 4 which are angularly out of phase with each other at the first separation angle θ. The first pair of probes 1, 2 and the second pair of probes 3, 4 are angularly out of phase with each other at a second separation angle β.

[0089] In the next section of this specification, we will study the advantages of such a configuration.

[0090] The permanent magnet A can be a multi - pole magnet or a magnet assembly, or an equivalent machined magnet. The magnet can consist of all or part of the rotor of an electric motor, a generator, an actuator, a gear reducer, a coupling, a gearbox or an oscillator. Alternatively, the permanent magnet can consist of a set of current loops.

[0091] The sensor also includes a processing circuit which is connected to the probes 1 - 4 and is configured to output a position signal depending on the absolute position (offset) of the permanent magnet A.

[0092] The magnetic position sensor C in accordance with the invention has a magnetization distribution following the teachings of the document FR3118804 cited in the introduction of this application. This distribution is complex and, based on the measurement of the air gap and the relative trajectory of the magnet, results in a multi - periodic variation of the magnetization distribution (or its orientation with respect to an axis or a reference point). The permanent magnet A generates a magnetic field that varies non - linearly along the direction of movement, and the variation takes a form corresponding to a combination of at least two different quasi - periodic contributions.

[0093] Thus, the magnetization distribution can be presented as a first so - called "loaded" pattern with a period p and including P measurement increments. It can also include a second so - called "carrier" mode with a period p*n (n real > 0; constant or variable), including N increments. This dual mode enables the combination of a rough detection (the global output of the sensor) and a finer detection of the absolute position (the local output of the sensor). The measurement increments are, for example, constituted by the measurement of magnetic poles. Thus, two poles of opposite polarity will be able to constitute a period of a given cycle. At least one magnetic anomaly can also be provided in the magnetization distribution, which results in an atypical flux used as an "event counting" indicator, so that the number of revolutions or events made beyond a first offset can be counted. The output signal includes a predetermined number T of measurement increments within a measurement interval.

[0094] By way of illustration, Figure 2shows the magnetization distribution for an angular travel of 360° (a full rotation), the three field components (radial component Br, tangential component Bt, and axial component Bz) from one of the probes 1 - 4, where the increment of the carrier signal is N = 2 and the increment of the signal being carried is P = 48. The number T of magnetic anomalies used as an indicator for "revolution counting" to assist in counting the number of revolutions is considered zero so as not to unnecessarily complicate the description of the present invention.

[0095] By wisely combining the measurements made by two probes from the same pair of probes, it is noted that there is always (at least) a first angular value (denoted as θ) separating these two probes, such that it is possible to generate a sine curve representing the period of the carrier signal by combining the measurements of the field components respectively generated by these two probes. This first angular value θ roughly corresponds to half the period of the signal being carried. Figure 3 shows the radial field measurements Br1, Br2 provided respectively by the first main probe 1 and the first secondary probe 2 for the first separation angle value θ of approximately 7.5° for these two probes 1, 2 (in this configuration, P = 48), and the addition Br1 + Br2 of these two signals.

[0096] By wisely combining the measurements made by the second main probe 3 and the second secondary probe 4 with the same phase shift of the first angular value θ, it can be seen that there is always (at least) a second angular value (denoted as β) separating the first main probe 1 and the first secondary probe 2 from the second main probe 3 and the second secondary probe 4 respectively, such that a second sine curve representing the period of the carrier signal can be generated by combining the measurements of the field components generated by these probes 3, 4, and this second sine curve is orthogonal to the sine curve obtained from the first pair of probes 1, 2. This second angular value β roughly corresponds to a quarter of the period of the carrier signal.

[0097] Figure 4 shows the results of the radial field measurements Br3, Br4 provided respectively by the probes in the second pair of probes 3, 4 for the second separation angle value β of approximately 90° (for this configuration, N = 2), and the addition Br3 + Br4 of these two measurements.

[0098] Figure 5 shows the results of the angular position calculation provided by the sensor C with the configuration described in the present invention, thus obtaining Figure 4 the results shown in. This calculation uses the arctangent of two orthogonal sine curves from the measured radial component Brad, combined by addition. Over a full rotation, the angular error of the calculated global position is + / - 5°.

[0099] The same strategy can be advantageously applied to the tangential Bt component and the axial Bz component of the field, respectively as Figure 6 and​​Figure 7 As shown. The tangential Bt component and the axial Bz component are combined additively in pairs. This enables three sets of curves to be obtained, which have similar intensities in pairs, thus enabling the overall angular value to be accurately calculated.

[0100] To calculate the local position, the same method can be used. This time, the field components are combined to highlight the signal being carried. In this case, by subtracting pairwise the components supplied by the probes of the same pair, as Figure 8 shown.

[0101] Therefore, Figure 9 shows the result of the angular position calculation provided by the sensor C having the configuration described in the present invention, thus obtaining the result shown in Figure 8 . This calculation uses the arctangent of two sine curves orthogonal to the radial component Brad. Over a part of a rotation, the angular error of the calculated local position is + / -3.5° (in the example configuration, it is a pair of increments of the signal being carried, i.e., approximately 15° mechanical angle). Therefore, the angular accuracy of the mechanical angle measurement is 3.5 / 24 pairs of increments (P = 48), i.e., + / -0.15°.

[0102] The same strategy can be advantageously applied to the tangential component Bt and the axial component Bz. Three sets of curves (not shown) can be obtained, which have similar intensities in pairs, thus enabling the local angular value to be accurately calculated.

[0103] This very general method makes it easy to understand the advantages of differential processing of at least one of the measured field components. "Differential processing or combination" is understood to mean combining the field components from at least some of the probes 1-4 of the sensor C by difference or addition. This enables the carrier signal for calculating the global angle (position in rotation) and the signal being carried for calculating the local angle (position in the considered increment) to be highlighted by basic calculations.

[0104] The simultaneous calculation of the two angular values guarantees an immediate and absolute knowledge of the precise angular (or linear) position, without the need for a minimum offset to complete the initial calculation.

[0105] The use of the component ratios utilized in the tangent arc calculation ensures that the angle calculation is essentially insensitive to temperature variations. The components are affected in the same way, so the ratio remains constant.

[0106] However, the previously used field components are still sensitive to external fields. To compensate for this phenomenon, the signals provided by the probes can be combined in order to incorporate external field compensation, such that the detection is insensitive to stray external fields.

[0107] Referring to Figure 1 , we note that:

[0108] - The first pair of probes 2 arranged along the first axis x measures Br2 + Hx, i.e., the radial field Br2 of the magnet plus the projection Hx of the external field Hext along the first axis x. Similarly, the second pair of probes 4 positioned along the second axis y orthogonal to the axis x measures Bt4 - Hx, i.e., the tangential field Bt4 of the magnet 4 minus the projection Hx of the external field Hext along the first axis x. Thus, the sum of these two measurements (Br2 + Hx) + (Bt4 - Hx) is not affected by the component Hx of the external field along the first axis x. The same observation can be made by selecting another pair of orthogonal probes 1, 3.

[0109] - The first pair of probes 2 positioned along the first axis x measures the tangential field Bt2 + Hy of the magnet, to which the projection Hy of the external field Hext along the second axis y is added. Similarly, the second pair of probes 4 arranged along the second axis y measures Br4 + Hy, and the radial field Br4 of the magnet 4 is also added with the projection Hy of the external field Hext along the second axis y. Thus, the difference between these two measurements (Bt2 + Hy) - (Br4 + Hy) is not affected by the component Hy of the external field Hext along the second axis y. The same observation can be made by selecting another pair of orthogonal probes 1, 3.

[0110] - Finally, the first pair of probes 2 positioned along the first axis x measures the axial field Bz2 + Hz of the magnet, to which the projection Hz of the external field Hext along the third axis z (forming a trihedron with the first axis x and the second axis y) is added. Similarly, the second pair of probes 4 arranged along the second axis y measures Bz4 + Hz, and the axial field Bz4 of the magnet 4 is also added with the projection Hz of the external field Hext along the axis z. Thus, the difference between these two measurements (Bz2 + Hz) - (Bz4 + Hz) is not affected by the component Hz of the external field Hext along the third axis z.

[0111] This description is based on the assumption that the external field impinges on all four probes uniformly. In practice, the distance between the probes is small but inevitable, which will cause minor variations, but has no significant impact on the final angular accuracy.

[0112] By combining the field components according to the following formula (whose expression is simplified):

[0113] · Br1 + Bt3 and Br2 + Bt4, and their addition;

[0114] · Br3 - Bt1 and Br4 - Bt2, and their addition;

[0115] A robust detection of the external magnetic field for global angular position calculation can be obtained, as shown in Figure 10 .

[0116] Figure 11 ​Shows the result of the angular position calculation provided by sensor C implementing the combination just presented. This calculation uses the arctangent (or Atan2 function) of the ratio of two curves of equal intensity:

[0117] ·Atan2((Br1 + Bt3)+(Br2 + Bt4); gain * ((Br3 - Bt1)+(Br4 - Bt2)))

[0118] · Adjust the gain value to minimize the angular error calculated based on the sensor offset (here 0.998)

[0119] The angle measured over a full mechanical rotation gives an angular position value of + / - 5° ( Figure 11 ).

[0120] Advantageously, by combining the field components according to the following formula (as Figure 12 shown):

[0121] · Br3 - Bt1 and Br4 - Bt2, and their subtraction;

[0122] · Bz1 - Bz2;

[0123] A robust detection of the external magnetic field for local angular position calculation can be obtained.

[0124] Use the arctangent (or Atan2 function) of the ratio of two curves of equal intensity to calculate the value of the local angular position:

[0125] · Atan2((Br3 - Bt1)-(Br4 - Bt2); gain * (Bz1 - Bz2))

[0126] · Adjust the gain value to minimize the angular error calculated based on the sensor offset (here 0.933)

[0127] The angle calculated over one period of the carrier signal (a pair of increments) gives a local angular position value of + / - 5° (electrical), as Figure 13 shown. Relative to the mechanical angle, the angular accuracy measured over the entire rotation is 5 / 24 = + / - 0.21° mechanical angle, where the angular error measured for each increment pair over the rotation remains very similar.

[0128] According to the Figure 14 shown specific embodiment, the combination of the field components according to the following formula:

[0129] · Bz1 + Bt3 and Bz2 + Bt4, and their subtraction;

[0130] · Bz3 - Bt1 and Bz4 - Bt2, and their subtraction;

[0131] A second detection for calculating the local angular position can be obtained, which has overall improved accuracy.

[0132] Use the arctangent (or Atan2) of the ratio of two curves of equal intensity to calculate the value of the local angular position:

[0133] ·atan2((Bz3 - Bt1) - (Bz4 - Bt2); gain * ((Bz1 + Bt3) - (Bz2 + Bt4)))

[0134] ·Adjust the gain value to minimize the angular error calculated based on the sensor offset (here it is 0.995).

[0135] The angles (a pair of increments) calculated over one period of the carrier signal give local angular position values (electrical) of + / - 3°, as Figure 15 shown. Relative to the mechanical angle, the angular accuracy measured over the entire rotation is 3 / 24 = + / - 0.125° mechanical angle, where the angular error measured for each increment pair over the rotation remains very similar.

[0136] Figure 16a and Figure 16b shows the influence of the external magnetic field Hext (measured separately at one probe: Bx = 10 mT, By = -3 mT, and Bz = 7 mT; uniform over all probes), which is the influence on the measured field components in the absence of the external field Hext ( Figure 16a ), and the influence in the presence of the external field Hext ( Figure 16b ).

[0137] Figure 17a 、 Figure 17b and Figure 18a 、 Figure 18b Compare the angular errors calculated in the two cases.

[0138] - In Figure 17, for (a) the global angular position and (b) the local position measured for one increment, there is an external field Hext.

[0139] - In Figure 18, for (a) the global angular position and (b) the local position measured for one increment, there is no external field Hext.

[0140] As expected, the signal remains unchanged. Other tested field strengths confirmed these measurements.

[0141] A person skilled in the art will be able to easily distinguish the differences between the present invention and the solution proposed in the prior art WO2009 / 101270, which is used to calculate the angular travel performed by radially detecting a ring magnetized in diameter for a field that varies linearly with the angular position. In the sensor C according to the present invention, the field measured by the magnetosensitive element does not vary linearly with the angular position. This is particularly evident in Figure 10 . Therefore, these two methods cannot be confused.

[0142] The sensor C according to the present specification may include a signal processing circuit to combine components and determine instantaneous global and local angular values. The circuit may also perform various compensations required to correct these angular values.

[0143] To reduce the calculation time, the device may combine the analog detection and digital detection of field components.

[0144] According to a specific embodiment, the sensor C further includes means for storing angular values and linear coefficients for compensating the linearity of the sensor. These storage resources can be accessed by the signal processing circuit, which can use them to apply processing to compensate for the linearity of the sensor.

[0145] According to a specific embodiment, the sensor further includes means for determining, based on the overall angular position, the facing of an increment or a pair of increments. This increment or pair of increments is referred to as "valid".

[0146] Each valid increment (for example) is associated with a serial number or a global angular position (identified, for example, by the zero crossing of one of the field components or a combination of components). This method ensures in a simple and accurate manner that the increment readings correspond to the calculated global values without the risk of errors with adjacent increments.

[0147] Each local angular value calculated at a valid increment can be used as a local angular value or a percentage of full scale, or directly as a global angular value (by dividing the read value by the number of increment pairs (here 24), and then adding it to the global angular position associated with the valid increment pair): for example, an increment calculated at a global position (zero crossing) corresponding to 157.3° that gives 183.4° immediately gives an angular position of 157.30 + 183.4 / 24 = 164.94°.

[0148] Since each increment may contain magnetization anomalies, the exact angular value of each increment can be used to conform to the true angular value read on the magnetic track. Thus, for a pair of increments of 15.7° (instead of the theoretically expected 15°): 157.30 + 183.4 / (360 / 15.7) = 165.29°.

[0149] According to a particular embodiment, an angular compensation coefficient is calculated for each increment (i) according to the following formula: Increment coefficient (i) = angular value of the theoretical increment / value of the measured increment. This coefficient is used to correct local and / or global angular values.

[0150] According to a particular embodiment, the field component detection mode can be axial or radial, or a combination thereof.

[0151] In a particular embodiment, the field component detection mode can be performed simultaneously on different faces of the magnetic target.

[0152] According to a particular embodiment, the sensor further comprises self-calibration means such that certain calculated values can be adjusted during the lifetime of the sensor to maintain an optimal performance level.

[0153] According to a particular embodiment, the sensor further comprises diagnostic means which are capable of signalling possible faults (probe, magnetosensitive element, magnetic track, communication, calculation, temperature, external field, sensor travel, speed, etc.) and of entering a possible degradation mode, thereby enabling the sensor to operate with reduced performance. In particular, this degradation mode enables detection to be carried out using a minimum number of magnetosensitive elements.

[0154] Figure 20 gives a good indication of the global position calculation using only the signals from 2 θ-shifted probes (e.g., the first pair of probes 1, 2 or the second pair of probes 3, 4 - left figure). The global position (graph on the right) is obtained using the Atan(Bz / Btan) calculation or the Asin(Brad) calculation, where Brad, Btan and Brz respectively correspond to the sum of the radial field component, tangential field component and axial field component provided by each of the two probes. The linearity of the calculation is + / −6° over a full mechanical rotation.

[0155] Figure 21 gives a good indication of the local position calculation using only the signals from 2 probes phase-shifted by a first angular value θ. The local position is obtained using the Atan(Bz / Btan) calculation or the Asin(Brad) calculation, where Brad, Btan and Brz respectively correspond to the difference between the radial field component, tangential field component and axial field component provided by each of the two probes ( Figure 21 b). The linearity of the calculation is + / −3° over a pair of increments, i.e., + / −0.125° or a full mechanical rotation.

[0156] According to the envisaged operating conditions, other combinations of field components for isolating the global angular position and / or local angular position can be selected to achieve an effective detection mode.

[0157] In particular, as​​Figure 22 as shown:

[0158] - The first pair of probes 1, 2 is phase-shifted by a first angular value θ corresponding to half a period of the signal being carried. This first pair of probes 1, 2 can be used to determine the local position.

[0159] - The second pair of probes 3, 4 is phase-shifted by an angular value corresponding to one signal period. This second pair of probes 3, 4 can be used to determine the global position.

[0160] In this case, the first and second probe pairs can be separated by any second angular value (β), for example chosen to be zero.

[0161] The method for determining the exact angular position based on the calculated angular measurements will first involve calculating the global and local positions. In a second step, compensation values for these angular positions can be defined. Finally, a detection diagnosis can be performed to verify the measurements and, if necessary, initiate a degraded detection mode. Values for the rotational speed and direction are determined from the calculated angular values.

[0162] According to a particular embodiment, a mathematical function (such as a polynomial) can be used to compensate for the angular value (or linear offset) calculation. Each increment will be associated with a set of coefficients (6 coefficients for a 5th-order polynomial) required to define the function and the function combination.

[0163] According to a particular embodiment, trigonometric functions (or their equivalents) can be used to compensate for the angular value (or linear offset) calculation. Each increment will be associated with a set of coefficients (e.g., intensity, period, angular deviation) required to define the function and the function combination.

[0164] According to a particular embodiment, the sensor can use only a very small number of magnetosensitive elements capable of measuring one or more field components, or any combination, to meet spatial or price requirements. This solution can also be envisaged for detection over a very limited stroke (for a rotational sensor < 360°).

[0165] In another variant, the measuring device can include a plurality of probes, each arranged at a specific point such that the operating mode can be doubled or tripled. By averaging all the values obtained from all these probes, an average angular value can be obtained, which reduces the uncertainty associated with a single set of probes (e.g., a set of 4 probes capable of measuring one or more field components). Thus, it is possible to envisage using 5, 6, 7, or 8 probes, for example, to create a fully redundant sensor for applications requiring maximum integrity and reliability (ASIL D type for automotive applications). This can also be used to enrich the combination of different field components.

[0166] Of course, the present invention is not limited to the described embodiments, and variant embodiments can be added thereto without departing from the scope of the invention defined by the claims.

[0167] In this way, the sensor C can assume a linear configuration as shown Figure 19 . This linear configuration can be obtained by mentally unfolding the solution obtained for axial or radial angle detection. Since the field distributions of the various field components are similar, the processing remains the same, taking care to correctly (linearly spaced) position the groups of magnetosensitive elements to obtain valid first angle values β and second angle values θ for differential analysis.

[0168] Regardless of whether the sensor C is linear or disc-shaped, the groups of magnetosensitive elements can be repositioned relative to the permanent magnet, so that the first angle value θ and / or the second angle value β can be adjusted.

[0169] In addition to measuring angular or linear displacements in complex systems, the sensor can also be used to measure quantities. The quantity values can correspond to force, torque, acceleration, braking, phase shift, overall speed, direction of movement, distance, number of revolutions, inertia, imbalance, vibration, noise, harmonic content, temperature, pressure, current, voltage, current, frequency, information coding.

Claims

1. A non-contact angular or linear magnetic position sensor (C), the magnetic position sensor comprising: · A permanent magnet (A) that generates a magnetic field that varies non-linearly in the direction of movement, the variation including a combination of at least one first quasi-periodic signal and at least one second quasi-periodic signal in various field components, the first quasi-periodic signal being referred to as the "carried signal" and the second quasi-periodic signal being referred to as the "carrier signal", the first signal and the second signal being different from each other, · At least one first pair of probes (1, 2; 3, 4), the at least one first pair of probes including a first main probe (1; 3) and a first secondary probe (2; 4), the first pair of probes being associated with the permanent magnet (A), and each probe being capable of measuring at least two field components at a single point; and · A processing circuit that is connected to the probes and is configured to utilize at least some of the measurements provided by the probes and deliver a position signal representing the absolute position of the permanent magnet (A), The sensor is characterized in that the two probes in the first pair of probes (1, 2) are separated by a first angular value (θ) corresponding to a half-period of the carried signal, such that the first quasi-periodic signal representing the global position and the second quasi-periodic signal representing the local position can be isolated by a differential combination of field component measurements.

2. The magnetic position sensor (C) according to the preceding claim, the magnetic position sensor including a second pair of probes (3, 4), the second pair of probes including a second main probe (3) and a second secondary probe (4) that are separated by an angular value corresponding to the period of the carried signal.

3. The magnetic position sensor (C) according to claim 1, the magnetic position sensor including a second pair of probes (3, 4), the second pair of probes including a second main probe (3) and a second secondary probe (4), the second pair of probes (3, 4) being associated with the permanent magnet (A), and each probe in the second pair of probes (3, 4) being capable of measuring at least two field components at the same point, the two pairs of probes (1, 2; 3, 4) being positioned relative to each other so as to obtain an orthogonal match obtained by differential combination from the signals.

4. The non-contact magnetic position sensor (C) according to the preceding claim, wherein the probes in the first pair of probes (1, 2) and the probes in the second pair of probes (3, 4) are separated from each other by a second angular value (β), the second angular value (β) being substantially equal to a quarter-period of the carrier signal.

5. The non-contact magnetic position sensor (C) according to the preceding claim, wherein the first angular value (θ) and / or the second angular value (β) is adjustable.

6. The non-contact magnetic position sensor (C) according to one of claims 3 to 5, wherein the processing circuit establishes: · Measuring the global position of the sensor by combining the field components according to the following formula: Atan2((Br1 + Bt3)+(Br2 + Bt4); gain * ((Br3 - Bt1)+(Br4 - Bt2))) or · Measuring the local position of the sensor by combining the field components according to the following formula: Atan2((Br3 - Bt1)-(Br4 - Bt2); gain * (Bz1 - Bz2)), where Bri, Bti and Bzi respectively represent the radial field, tangential field and axial field measured by the probe with index i, and where the gain is a selected quantity so as to minimize the angular error calculated according to the offset of the sensor.

7. The non-contact magnetic position sensor (C) according to one of claims 3 to 6, wherein the processing circuit establishes: measuring the local position of the sensor by combining the field components according to the following formula: Atan2((Bz3 - Bt1)-(Bz4 - Bt2); gain * ((Bz1 + Bt3)-(Bz2 + Bt4))), where Bri, Bti and Bzi respectively represent the radial field, the tangential field and the axial field measured by the probe with index i, and where the gain is a selected quantity so as to minimize the angular error calculated according to the offset of the sensor.

8. The non-contact magnetic position sensor (C) according to one of the preceding claims, wherein the permanent magnet (A) is a multi-pole magnet or a magnet assembly or an equivalent machined magnet.

9. The non-contact magnetic position sensor (C) according to one of claims 1 to 7, wherein the permanent magnet (A) consists of a set of current loops.

10. The non-contact magnetic position sensor (C) according to one of the preceding claims, wherein the permanent magnet (A) consists of all or part of the rotor of an electric motor, a generator, an actuator, a gear reducer, a coupling, a gearbox or an oscillator.

11. The non-contact magnetic position sensor (C) according to one of the preceding claims, wherein each probe (1, 2; 3, 4) comprises a plurality of magneto-sensitive elements selected from the list consisting of Hall probes, magnetoresistive elements, eddy current elements and detection coils.

12. The non-contact magnetic position sensor (C) according to one of the preceding claims, wherein the permanent magnet (A) has the shape of a disc, a ring or a cylinder, and the probes in at least one pair of probes (1, 2; 3, 4) are arranged on the periphery of the magnet.

13. The non-contact magnetic position sensor (C) according to one of the preceding claims, wherein the processing circuit is configured to correct the calculated angular value using an angular compensation factor.

14. The non-contact magnetic position sensor (C) according to the preceding claim, wherein the correction of the calculated angular value is based on trigonometric functions.

15. The contactless magnetic position sensor (C) according to one of the two preceding claims, wherein the processing circuit is configured to combine the analog detection and the digital detection of the field components.

16. Use of a contactless magnetic position sensor (C) according to any one of the preceding claims for measuring added values on a complex system, said added values including force, torque, acceleration, braking, phase shift, overall speed, direction of movement, distance, number of revolutions, inertia, imbalance, vibration, noise, harmonic content, temperature, pressure, current, voltage, current, frequency, information coding.

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