Gyroscopic measurement method and sensor

Abstract

Gyroscopic Measurement Method and Sensor The present invention relates to a gyroscopic measurement method using a sensor (10) comprising a housing (12) and a vibrating element (15) capable of vibrating relative to the housing (12) simultaneously along a direction (x) of a pilot mode and a direction (y) of a detection mode, comprising the control (110) of a first and a second vibration amplitude of the vibrating element (15) along the directions of the pilot mode and the detection mode respectively to a predetermined pilot amplitude (xmax) and a detection amplitude (ymax), and the determination (120) of an instantaneous angular velocity (Ωmes) of the housing (12).A predetermined bias (ξ(t)) is introduced into a measurement of an angular position (θ) of the direction (x) of the pilot mode used to determine a biased force (Fass,bias) to be exerted on the vibrating element (15) for the control of the first and / or second vibration amplitude, to cause a controlled rotation of the direction of the pilot mode (x) in the vibration plane (XY). Figure for the abstract: 3.

Description

Title of the invention: Gyroscopic measurement method and sensor

[0001] The present invention relates to a gyroscopic measurement method.

[0002] The invention also relates to a gyroscopic sensor for implementing the gyroscopic measurement method, as well as a computer program comprising instructions that lead the sensor to perform the step of determining the instantaneous angular velocity of the gyroscopic sensor of this method.

[0003] A Coriolis Vibratory Gyroscope (CVG) sensor allows measurement of the component along an axis, called the sensitivity axis, of an instantaneous rotation velocity vector of a reference frame attached to a sensor housing with respect to an inertial reference frame.

[0004] The CVG comprises for this purpose a vibrating element of the sensor capable of vibrating relative to the housing. The measurement is carried out by means of the effects of the Coriolis inertial force exerted on the vibrating element.

[0005] The vibrating element of a CVG is capable of vibrating along two coplanar and perpendicular vibration directions, called the pilot mode direction and the detection mode direction, the work of the Coriolis force allowing a transfer of mechanical energy between the two directions.

[0006] The sensitivity axis of the CVG is orthogonal to the plane of the perpendicular directions of the pilot mode and the detection mode.

[0007] For the measurements, the vibrating element is excited along the pilot mode direction at its resonant frequency by the excitation system. The amplitude of the vibrations along the pilot mode is kept constant by means of an amplitude control applied to the excitation system. Any variations in the resonant frequency, particularly those related to variations in the temperature of the vibrating element, are monitored by means of a phase-locked loop.

[0008] If the component along the sensitivity axis of the instantaneous rotational velocity vector of the housing with respect to an inertial reference frame is non-zero, the displacement of the vibrating element along the direction of the pilot mode generates a Coriolis force. This Coriolis force excites the vibrating element along the direction of the detection mode, perpendicular to the direction of the pilot mode, with an amplitude that is proportional to the component along the sensitivity axis of the instantaneous rotational velocity vector.

[0009] A CVG can operate in two modes: gyroscope mode and gyrometer mode.

[0010] In gyroscope mode, the position of the pilot mode direction in the vibration plane is free. The instantaneous rotational speed to be measured is then deduced from the angular position of the vibration plane of the vibrating element in the reference frame attached to the housing.

[0011] In gyroscope mode, the direction of the pilot mode in the plane of vibration is controlled by sending an electronic command and the instantaneous rotation speed to be measured is deduced from the force to be exerted to control this direction.

[0012] Whether the CVG is used in gyroscope mode or gyrometer mode, the measurements are affected by intrinsic errors related to defects in the CVG. Among these defects, we can mention the anisotropies of stiffness or damping of the vibrating element, defects in the excitation control electronics or the position detection electronics of the vibrating element, defects in the electrical reference voltage for the excitation, etc.

[0013] Among these errors, some are called harmonic because they are proportional to cosine or sine functions of an angle that is an even multiple of the angle characterizing the direction of the pilot mode in the reference frame linked to the housing.

[0014] US 6 598 455 describes a method of gyroscopic measurements in which the geometric vibration position of the gyroscope is intentionally modified by electrostatic means over time, in order to improve the calibration of the gyroscope.

[0015] US 7 093 370 further describes a MEMS gyroscope in which an angular velocity is intentionally imposed on the sensor by mechanical means, the direction of rotation of the sensor being periodically alternated in order to reduce measurement errors and in particular scaling factor errors of the gyroscope.

[0016] FR 2937414 describes a vibrating gyroscope that combines the principles of US patent 6,598,455, by injecting an electronic signal to rotate the vibration base, and US patent 7,093,370, by imposing a periodically alternating electrical rotation to minimize harmonic errors. The control signal is adapted to rotate the geometric vibration position of the gyroscope in a first direction for a portion of the control signal period according to a first velocity profile, and then in the opposite direction according to a second velocity profile. The vibrating gyroscope then provides a corrected signal based on the difference between the measurement signal and the control signal.

[0017] However, due to errors in the chain converting the control signal into an electrostatic force, the force actually applied to the vibrating element of the gyroscope to obtain its alternating rotation is different from the force that should theoretically be obtained from the control signal.

[0018] If the errors of the conversion chain are perfectly stable over time, the error made on the angle measurement can be zero over a period characteristic of the variations of the control signal.

[0019] However, this is very unlikely, as the sources of error are numerous and of different kinds. These include, in particular, errors in the detection of the combs of detection, excitation errors of the excitation combs, as well as instabilities of the reference voltage used for the operation of these combs, and errors of the electronic boards which coordinate the implementation of the gyroscopic measurement process.

[0020] In the end, in most situations, the average value of the error committed is not zero over a period of the alternating rotation of the sensor position in the frame linked to the sensor housing.

[0021] Moreover, during the round trip of the wave, the angular errors of the sensor are all the greater as the aforementioned defects are significant.

[0022] Such a device reduces the impact of defects on the measurement without however allowing the measurement error related to these defects to be evaluated.

[0023] Furthermore, the control signal used in FR 2937414 must allow the gyroscope to return to the same angular position between the beginning and end of the control period. In cases where the gyroscope is moving in the inertial frame of reference and not at rest, such a signal will not allow both a zero-average control signal and a return to the same angular position.

[0024] An object of the invention is to provide a gyroscopic measurement method in which an alternating rotation of the directions of the pilot and detection modes of the gyroscopic sensor is controlled and in which measurement errors, in particular the scale factor error, are reduced. To this end, the invention relates to a gyroscopic measurement method using a sensor comprising a housing and a vibrating element capable of vibrating relative to the housing in a vibration plane attached to the housing simultaneously along a direction of a pilot mode and along a direction of a detection mode different from the direction of the pilot mode, the method comprising the following steps:

[0025] a) controlling a first vibration amplitude of the vibrating element along the direction of the pilot mode to a predetermined pilot amplitude, and a second vibration amplitude of the vibrating element along the direction of the detection mode to a predetermined detection amplitude, and b) determination of an instantaneous angular velocity of the housing relative to a sensitive axis of the sensor from measurements of the vibrations of the vibrating element and the pilot amplitude, the method being characterized in that a predetermined bias is introduced into a measurement of an angular position of the pilot mode direction used to determine a biased force to be exerted on the vibrating element for the control of the first and / or second amplitude of vibrations, the introduction of the predetermined bias causing a controlled rotation of the pilot mode direction in the vibration plane,

[0026] the instantaneous angular velocity of the housing being further determined from the predetermined bias.

[0027] The introduction of a predetermined bias during the process results in the application of an amplitude control force that no longer has the same direction as the pilot mode, as in prior art processes, but an offset direction. The offset is a function of the bias that has been introduced.

[0028] This offset implies that the force exerted for amplitude control has a component orthogonal to the direction that would be desired in the absence of bias, which is added to the Coriolis force due to the rotational movement of the housing in the inertial frame of reference. A rotation of the perpendicular directions of the pilot mode and the detection mode is induced, without the need for an additional force whose control would present difficult-to-manage defects.

[0029] The bias can also be a predetermined function that varies over time. If this function is chosen judiciously, it is possible to cancel the harmonic defects of the sensor on which the process is implemented.

[0030] The gyroscopic measurement method according to the invention therefore makes it possible to carry out gyroscopic measurements of increased precision.

[0031] According to other advantageous aspects of the invention, the gyroscopic measurement method comprises one or more of the following features, taken individually or in all technically possible combinations:

[0032] - the predetermined bias is configured to cause a rotation of the direction of the pilot mode of a predetermined angle alternately in a first direction and in a direction opposite to the first direction;

[0033] - the predetermined angle is equal to 90°;

[0034] - the detection amplitude is chosen to be zero;

[0035] - the control stage includes: 1) a measurement of the vibrations of the vibrating element; 2) an estimation of a characteristic phase of the vibrations of the vibrating element along the direction of the pilot mode from the measurement results; 3) a first estimate of a first force whose direction is the direction of the pilot mode to be exerted on the vibrating element to control the first amplitude from the results of the measurement and the estimated phase; 4) a second estimate of a second force whose direction is the direction of the pilot mode to be exerted on the vibrating element to control the second amplitude from the results of the measurement and the estimated phase; 5) the introduction of the predetermined bias in the directions of the first force and the second force; 6) the control of the biased force which is equal to the resultant of the first force and of the second force after introduction of the predetermined bias in the directions of these two forces;

[0036] - the second force comprises only a component in phase with the vi vibrations of the vibrating element according to the direction of the pilot mode.

[0037] The invention also relates to a gyroscopic sensor comprising a housing and a vibrating element capable of vibrating relative to the housing in a vibration plane linked to the housing simultaneously along a direction of a pilot mode and along a direction of a detection mode different from the direction of the pilot mode and configured to implement the steps of the process according to any one of the preceding embodiments.

[0038] According to other advantageous aspects of the invention, the gyroscopic sensor comprises one or more of the following features, taken individually or in all technically possible combinations:

[0039] - the sensor comprises: a) a first control module, configured to estimate a first force to be exerted along the direction of the pilot mode to control a first amplitude of vibrations of the vibrating element along the direction of the pilot mode to a predetermined pilot amplitude; b) a second control module, configured to estimate a second force to be exerted along the direction of the detection mode to control a second vibration amplitude of the vibrating element along the direction of the detection mode to a predetermined detection amplitude; c) a measurement module, configured to generate vibration measurements of the vibrating element along two directions of a frame attached to the housing contained in the vibration plane; d) a control module, configured to determine a biased force to be exerted on the vibrating element for the control of the first and / or second amplitude of vibrations, from the first force and the second force and from a biased angular position of the pilot mode direction in the frame attached to the housing which corresponds to an angular position of the pilot mode direction in the frame attached to the housing after introduction of a predetermined bias, and to exert the biased force; (e) bias means, configured to provide the biased angular position to the control module from measurements of the vibrations of the vibrating element along the two directions of a frame of reference attached to the housing and the predetermined bias, the introduction of the predetermined bias being configured to cause a controlled rotation of the pilot mode direction in the plane of vibration when the biased force is applied; and f) a determination module, configured to determine an angular velocity instantaneous of the housing relative to a sensitive axis of the sensor from measurements of the vibrations of the vibrating element, the pilot amplitude and the predetermined bias.

[0040] - the means of biasing the sensor include: 1) a coordinate system change module, configured to generate vibration estimates of the vibrating element along the pilot mode direction and the detection mode direction from vibration measurements of the vibrating element along the two directions of a coordinate system linked to the housing provided by the measurement module and the biased angular position provided by a bias correction module; 2) a phase module, configured to receive as input estimates of the vibrations of the vibrating element along the direction of the pilot mode from the coordinate system change module and to estimate a phase characterizing a position of the vibrating element along the direction of the pilot mode at a current date; 3) a precession module, configured to receive vibration estimates of the vibrating element along the directions of the pilot mode and the detection mode from the coordinate system change module and the phase of the phase module, and to provide as output an estimated difference between the angular position of the pilot mode direction in the coordinate system linked to the housing at the current date and a biased angular position previously provided by the correction module, and 4) the correction module, configured to provide the biased angular position to the control module from the estimated difference, the correction module comprising: (i) a summing stage, configured to add the predetermined bias to said estimated difference; and ii) a feedback loop to the reference frame conversion module, the feedback loop comprising a gain stage and an integrator stage, the correction module is configured so that the estimated difference converges to a zero value.

[0041] The invention also relates to a computer program comprising instructions which lead the sensor according to one of the preceding embodiments to execute the process according to any of the embodiments described above.

[0042] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0043] [Fig-1] [Fig.1] is a schematic representation of part of the elements of a embodiment of a CVG according to the invention, including the vibrating element and the detection and excitation devices for this vibrating element;

[0044] [Fig.2] [Fig.2] is a schematic representation of the trajectory of the element vibrating from [Fig. 1] and the directions of its pilot and detection modes in a frame space related to the casing;

[0045] [Fig.3] [Fig.3] is a partial representation of an embodiment of the CVG, complementary to the representation of [Fig.1];

[0046] [Fig.4] [Fig.4] is a flowchart representation of the process according to the invention;

[0047] [Fig.5] [Fig.5] is a schematic representation of a CVG of the prior art;

[0048] [Fig.6] [Fig.6] is a schematic representation of one embodiment of a excitation device of the [Fig. 1]; and

[0049] [Fig.7] [Fig.7] shows a particular embodiment of the correction module of the [Fig.3].

[0050] The Coriolis effect gyroscopic sensor 10, designated by the abbreviation CVG in the following, according to the invention is described with reference to figures 1 and 3.

[0051] The CVG 10 comprises a housing 12 and a vibrating element 15 capable of vibrating relative to the housing 12.

[0052] The CVG 10 is, for example, implemented as a microelectromechanical system (MEMS). The vibrating element 15 and the housing 12 are then machined from a block of silicon or quartz by micromachining, and the vibrating element 15 is set into vibration by an electrical process. This arrangement minimizes the size and / or manufacturing cost of the CVG 10.

[0053] Three axes X, Y, Z of the XYZ space frame of a reference frame (XYZ, t) linked to the housing 12 are shown on [Fig.1], the Z axis being of fixed direction in a space frame of an inertial reference frame.

[0054] The CVG 10 is configured to measure an instantaneous angular velocity Q(t) of the sensor with respect to the Z axis, which therefore constitutes the sensitivity axis (or equivalently the sensitive axis) of the CVG 10.

[0055] To this end, the vibrating element 15 comprises a test mass M, capable of vibrating in the XY plane along two directions x and y, with a natural frequency co0x, respectively co0y close to co0x-

[0056] In the following, the x direction is considered to be the direction of the pilot mode and the y direction to be the direction of the detection mode. The y direction of the detection mode is perpendicular to the x direction of the pilot mode.

[0057] The test mass M is capable of vibrating along the x direction of the pilot mode x and the y direction of the detection mode, with a resonance frequency co close to co0x-

[0058] The CVG 10 includes a measuring module 20 capable of generating measurements of the vibrations of the vibrating element 15 along the X and Y directions of the reference frame linked to the housing 12.

[0059] In particular, the measuring module 20 is capable of measuring the position X(t) (respectively Y(t)) of the vibrating element 15, and / or indirectly its velocity dX / dt(t) (respectively dY / dt(t)), and / or indirectly its acceleration d2X / dt2(t) (respectively d2Y / dt2(t)) along the X direction (respectively along the Y direction) of the frame linked to the case 12.

[0060] To this end, the measuring module 20 may include suitable detection means, such as, for example, electrostatic detection means 20A along the X direction of the marker linked to the housing 12 and electrostatic detection means 20B along the Y direction of the marker linked to the housing 12.

[0061] Advantageously, the electrostatic detection means 20A and 20B each form with the test mass M a set of interdigitated combs, on the geometric principle represented in [Fig.6].

[0062] The measurement module 20 advantageously includes a proximity card configured to amplify the signals detected by the measurement module 20.

[0063] The measuring module 20 is capable of transmitting the measurements of the vibrating element to a reference frame change module 21.

[0064] The coordinate system change module 21 is capable of generating estimates of the vibrations of the vibrating element 15 along the x directions of the pilot mode and y of the detection mode, from measurements of the vibrations of the vibrating element along the X and Y directions of the coordinate system linked to the housing 12 and a biased estimate 0biais of an angular position 0 of the x direction of the pilot mode in the coordinate system linked to the housing 12 received from a correction module 50 which will be described later.

[0065] In particular, the coordinate system change module 21 is capable of estimating the position x(t) (respectively y(t)) of the vibrating element 15 and / or indirectly its velocity dx / dt(t) (respectively dy / dt(t)) and / or indirectly its acceleration d2x / dt2(t) (respectively d2y / dt2(t)) along the direction x of the pilot mode (respectively along the direction y).

[0066] The reference frame change module 21 is capable of transmitting the generated estimates to a phase module 30, a first control module 35 and a second control module 40.

[0067] The phase module 30 is configured to estimate a phase <p(t) caractérisant la position de la masse M selon la direction x du mode pilote à la date courante t. Par exemple, la phase <p(t) est de la forme <p(t) = cot+q>0, where q>0 denotes a phase at the origin of the dates t.

[0068] The phase module 30 is configured to receive as input estimates of the position of the mass M along the x direction of the pilot mode from the coordinate system change module 21.

[0069] The phase module 30 is configured to transmit the phase <p(t) estimée au premier module d’asservissement 35 et au deuxième module d’asservissement 40.

[0070] The first servo module 35 is configured to estimate, from the es Vibration timations of the vibrating element 15 along the x direction of the pilot mode and the phase<p(t), une première force Fass> x whose direction is the x direction of the pilot mode. The first force Fass>x is the force that must be exerted on the vibrating element 15 to control a first characteristic amplitude of vibrations of the vibrating element 15 to a predetermined non-zero pilot amplitude xmax, the vibrating element 15 vibrating in sinusoidal regime, at the resonance pulsation co, along the x direction of the pilot mode.

[0071] The first servo module 35 is configured to transmit the first estimated force Fass>x to a control module 45 which will be described later.

[0072] The first servo module 35 includes, for example, a processor or a programmable logic circuit (such as a "Field Programmable Gate Array", FPGA), configured to manage the estimation of the first force Fass>x, as well as a proximity card configured to transmit this estimation to the control module 45.

[0073] The second servo module 40 is capable of estimating, from the vibration estimates of the vibrating element 15 along the y direction of the detection mode transmitted by the coordinate transformation module 21 and the phase<p(t), une deuxième force Fass> y whose direction is the y direction of the pilot mode. The second force Fass>y is the force that must be exerted to control a second characteristic amplitude of vibrations of the vibrating element 15 along the y direction of the detection mode to a detection amplitude ymax, the vibrating element 15 vibrating in sinusoidal regime along the y direction of the detection mode at the resonance pulsation co.

[0074] The second servo module 40 is configured to transmit the second estimated force Fass>y to the control module 45.

[0075] The second servo module 40 includes, for example, a processor or a programmable logic circuit, such as an FPGA.

[0076] The processor or programmable logic circuit of the second servo module 40 can be the same as that of the first servo module 35. This arrangement is advantageous but not mandatory.

[0077] The proximity map of the second servo module 40 is, for example, the same as that of the first servo module 20. This arrangement is advantageous without being mandatory.

[0078] The control module 45 is configured to: a) Determine a third biased force Fass>Xjbiaise and a fourth biased force Fass>Y biaiS to be actually exerted along the X and Y directions of the XYZ frame attached to the housing 12, from: - of the first estimated force FasSjX, - of the second Fass force, estimated, and - of a biased angular position 0 biased to the x direction of the pilot mode, and b) to actually exert the third biased force Fass>x,biaiSet the fourth force biased Fass YjbiaiS on the vibrating element 15.

[0079] The control module 45 includes, for example, a processor or a programmable logic circuit, such as an FPGA, 45A configured to determine the third biased force Fass>Xjbiaiset the fourth biased force Fass YjbiaiS.

[0080] The control module 45 includes excitation means 45B and 45C of the vibrating element 15 along respectively the X direction and the Y direction of the XYZ frame linked to the housing 12.

[0081] These means are not shown in detail in Figures 1 and 3. They include, for example, the excitation means described in document EP2960625.

[0082] By way of example, the excitation means 45B include an electrostatic device configured to exert on the vibrating element 15 the third biased force Fass>x biaiS along the X direction of the XYZ frame linked to the housing 12.

[0083] By way of example, the excitation means 45C include an electrostatic device configured to exert on the vibrating element 15 the fourth biased force Fass>Y >bias along the Y direction of the XYZ frame linked to the housing 12

[0084] The electrostatic device of the excitation means 45B and / or 45C and the test mass M of the vibrating element 15 form, by way of example, a set of interdigitated combs, as shown in [Fig.6].

[0085] In this case, the control module 45 advantageously includes a proximity card, configured to inject an amplitude control signal into each of the electrostatic devices of the excitation means 45B and / or 45C.

[0086] The processor or programmable logic circuit of the control module 45 is advantageously configured to manage the control of the vibration pulse of the vibrating element 15 according to the y direction of the detection mode, for example to the resonance pulse co.

[0087] The control module 45 receives the biased angular position 0bias of the x direction of the pilot mode from a correction module 50.

[0088] The correction module 50 is configured to receive from the precession module 25 an estimated difference θ between the angular position θ of the pilot mode direction x estimated by the precession module 25 and the biased angular position θ bias and a bias function ^(t), and to provide as output the biased angular position θ bias*

[0089] To this end, the correction module 50 includes a processor or a programmable logic circuit (such as an FPGA).

[0090] The bias function ^(t) can be constant or depend on the time t at which the biased angular position 0biais is calculated.

[0091] The biased angular position 0biais of the rotating frame is the result of applying the bias function ^(t) in the estimation of the angle 0 by the correction module 50.

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101] It is understood from [Fig.3] that the biased angular position 0biais at the output of the correction module 50 is used by the change of reference module 21. The precession module 25 is used to determine the estimated difference ô supplied at the input of the correction module 50. The estimated difference ô used by the correction module 50 to determine the biased angular position 0biais at a given date t is calculated among other things from a biased angular position 0biaismesure at a date prior to date t. The precession module 25 is configured to receive vibration estimates of the vibrating element 15 along the x direction of the pilot mode and the y direction of the detection mode from the coordinate system change module 21 and the phase <p(t) du module de phase 30 et pour fournir en sortie la différence estimée ô. The precession module 25 constitutes an element of a tracking loop configured to estimate the biased angular position 0biais step by step, from a known unbiased initial angular position Oimtiaie and a demodulation of the position estimate of the vibrating element 15 according to the directions of the pilot and detection mode. In particular, the tracking loop also includes the correction module 50, the correction module 50 itself comprising an integrator circuit 504 and a gain module 503 which will be described later with reference to [Fig. 7], the variation of the biased angular position 0biais over an integration period T being calculated on the basis of the following equations: ' rnT J(„-i)rx(t) • cos( tp(t) )dt enT 10bias (t + dt) = ebias (t) + K tan4 (Qn) dt The precession module 25 is capable of transmitting the estimated difference ô to the correction module 50. The CVG 10 also includes a determination module 55 capable of determining a measured instantaneous angular velocity Qmes(t), which is an estimator of the desired angular velocity Q(t), from the estimated biased angular position 0biais and the bias function ^(t). We will now describe the method 100 according to the invention with reference to [Fig.4], in comparison with a prior art method 200 implemented on the CVG shown in [Fig.5]. The method 100 according to the invention comprises: a) a control step 110 of the first amplitude of the vibrations of the vibrating element 15 along the direction x of the pilot mode to the pilot amplitude xmax pre determined, and the second amplitude of the vibrations of the vibrating element 15 along the y direction of the detection mode at the predetermined detection amplitude ymax, during which the predetermined bias function ^(t) is introduced into the measurement of the angular position 0 of the pilot mode direction used to determine a force Fass to be exerted on the vibrating element for the control of the first and second vibration amplitudes, and b) the determination 120 of an instantaneous angular velocity Qmes of the housing 12 with respect to the sensitive axis Z of the sensor 10 from measurements of the vibrations of the vibrating element (15), of the pilot amplitude xmax and of the predetermined bias function ^(t).

[0102] The servo stage 110 is shown in detail in [Fig.4].

[0103] The control step 110 includes a first calculation step 1101 of the first force Fass x, whose direction is the x direction of the pilot mode, to be exerted on the vibrating element 15 to control the first amplitude to the pilot amplitude xmax.

[0104] The first calculation step 1101 is implemented by the first control module 35.

[0105] For this purpose, the first servo module 35 receives from the coordinate system transformation module 21 estimates of the vibrations of the vibrating element 15 along the x direction of the pilot mode. These estimates are based on measurements previously taken by the measurement module 20 during a measurement step 1102a of the vibrations of the vibrating element 15, and obtained during a coordinate system transformation step 1102b performed by the coordinate system transformation module 21.

[0106] The first servo module 35 also receives the phase q> previously estimated by the phase module 30 in a phase estimation step 1103 from the measurements of the vibrations of the vibrating element 15 along the direction x of the pilot mode carried out in the measurement step 1102.

[0107] Simultaneously, the control step 110 includes a second estimation step 1104 of the second force Fassy whose direction is the y direction of the detection mode to be exerted on the vibrating element 15 to control the second amplitude to the detection amplitude ymax.

[0108] The second estimation step 1104 is implemented by the second control module 40 based on the vibration estimates of the vibrating element 15 along the y direction of the detection mode from the coordinate system change step 1102b and transmitted by the coordinate system change module 21, and of the phase <p(t) estimée par le module de phase 30 à l’étape d’estimation de phase 1103.

[0109] It should be noted that the fact that the coordinate system conversion module receives the biased angular position 0 bias and not the angular position 0 has a negligible impact on the accuracy of the vibration estimation of the vibrating element 15 along the x direction of the pilot mode and the y direction of the detection mode. In particular, the difference between The biased angular position 0 and the angular position 0 of the ellipse described by the oscillation can be limited by choosing a suitable bias function. The control step 110 further includes a third estimation step 1105 of the difference θ.

[0110] The third estimation step 1105 is implemented by the precession module 25 based on the vibration estimates of the vibrating element 15 along the x direction of the pilot mode and along the y direction of the detection mode from the coordinate system change step 1102b, as well as from the phase <p(t) estimée par le module de phase 30.

[0111] It should be noted that it is in no way necessary to use an explicit calculation of the angular position 0 to estimate the difference ô. Indeed, this difference is estimated step by step using the tracking loop comprising the precession module 25 and the correction module 50, from the known initial angular position 0initiaie.

[0112] Following the third estimation step 1105, a bias step 1106 is implemented by the correction module 50.

[0113] During the bias step 1106, the biased angular position 0bias of the pilot mode direction is determined step by step by the correction module 50 from a difference ô estimated at the previous instant and the bias function ^(t).

[0114] A control step 1107 is then implemented by the control module 45. The control step includes a determination substep 1107a and an exercise substep 1107b.

[0115] During the determination substep 1107a, the processor 45A of the control module 45 receives the first Fassx force estimated during the first estimation step 1101 and the second Fassy force estimated during the second estimation step 1104.

[0116] The 45A processor also receives the biased angular position 0bias.

[0117] The processor 45A then determines the third biased force Fass>Xjbiais and the fourth biased force Fass>Yjbiais to be actually exerted along the X and Y directions of the XYZ frame linked to the housing 12 from the first estimated force Fass>x, the second estimated force Fass>y, and the biased angular position 0biais of the x direction of the pilot mode, considering that the biased angular position is the actual angular position of the x direction of the pilot mode.

[0118] Then during exercise substep 1107b, the third biased force Fass>x,biaiSet the fourth biased force FasSjYjbiaissont exerted by the excitation means 45B, 45C on the vibrating element 15.

[0119] Due to the introduction of the bias, the resultant of the third biased force Fass>x,biaiSet of the fourth biased force FasSjYjbiais does not have the necessary direction for the control, but a biased direction, as seen in [Fig.2].

[0120] As a result, an additional rotation of the direction of the detection mode is caused, this rotation being controlled by means of the bias function ^(t).

[0121] This additional rotation is added to the rotation caused by the Coriolis force associated with the angular velocity Q(t) that we seek to measure.

[0122] To better understand the effects obtained during the control step 1107, we will first describe the operating equations of the CVG 10 common to the process 100 according to the invention and to a prior art process, then we will describe more precisely a prior art process and finally, we will detail the particularities of the process according to the invention.

[0123] I) OPERATING EQUATIONS COMMON TO THE PRIOR ART PROCESSES AND THE PROCESS ACCORDING TO THE INVENTION

[0124] The following section describes the operating equations common to the prior art processes and the process according to the invention, equations which underlie the operation of the first and second servo modules 35 and 40 and of the control module 45 in the case of the sensor 10 according to the invention.

[0125] To simplify the writing of the equations enabling understanding of the prior art process and the process 100 according to the invention, the vibrating element 15 is modeled in the following by a mass M suspended on a rigid frame C by means of two pairs of springs 15A, 15B of respective stiffnesses Kx and Ky, as shown in [Fig.1].

[0126] Furthermore, it is assumed in the following that the stiffness constants and natural frequencies of the vibrating element 15 are identical in pilot mode x and mode y. In this particular case, we can therefore write that Kx = Ky = K and that co0x = (¾ = «o-

[0127] This simplification should in no way be considered as limiting the operation of the sensor 10 according to the invention, the following equations being able to be rewritten without difficulty in the most general case.

[0128] In general, the trajectory of the mass M in forced sinusoidal regime is an ellipse in the (X,Y) plane.

[0129] This ellipse is reduced to a straight line segment whose direction is the x direction of the pilot mode in the case where the amplitude of the vibrations according to the detection mode is controlled to a zero detection amplitude ymax.

[0130] Without making any assumptions at this stage about the value of the detection amplitude ymax, the position x of the mass M along the x direction of the pilot mode as a function of time t is of the form x(t) = xmaxcos(cot+q>0) and the position y of the mass M along the y direction of the detection mode as a function of time t is of the form y(t) = ymaxsin(cot+q>0)-

[0131] To simplify the writing of the equations, we consider that the phase at the origin of the dates <poest nulle, sans que cela n’ait d’impact sur le fonctionnement du procédé selon the invention.

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] If the x direction of the pilot mode with respect to the X axis of the XYZ frame linked to the housing 12 is located by the angle 0 shown in [Fig.2], the X and Y coordinates of the mass M in the XYZ frame linked to the housing 12 are related to the x and y coordinates of the mass M in the xyZ frame by equation 1: [XI [ms# -WZ01 p] _ [X] M in which R(0) is the change-of-basis matrix from the xy coordinate system to the XY coordinate system: [c^*9 -stWl L sin0 cosO J \ / The transition matrix R(0) is a function of time if the direction of the pilot mode is not constant in the XYZ frame linked to the housing 12. The first time derivatives dX / dt and dY / dt of the X and Y coordinates of mass M therefore satisfy: The second time derivatives d2X / dt2 and d2Y / dt2 of the X and Y coordinates of the mass M, for its part, satisfies: In a forced sinusoidal regime at angular frequency co, if we neglect the terms that are not proportional to a positive integer power of the angular frequency co compared to the other terms, equation 4 can be written in the simplified form of equation 5: =Æ(0) ■ v 420X + V In the frame of reference of housing 12, the mass M is subjected to the resultant force Fass exerted by the excitation means 45B, 45C for its control, the component of which along the x direction of the pilot mode (respectively the X direction of the frame linked to the housing 12) is noted Fass>x (respectively Fass>x) and the component along the y direction of the detection mode (respectively the Y direction of the frame linked to the housing 12) is noted Fass>y (respectively FasSjY) The mass M is also subject to the restoring forces of the springs, as well as to damping which is modeled by a fluid friction force along each of the x and y directions associated with a quality factor Q. The damping matrix A of the vibrating element 15, taking into account damping anisotropies, is of the form: 4 _ [ 1 01 , [ tü «2 ] (A a -“LawJ + l«2-«iJ h

[0146] The stiffness matrix Kl of the vibrating element 15, taking into account anisotropies of stiffness, is of the form:

[0147] Furthermore, when the frame of reference of the housing 12 is undergoing a rotational motion of component Q(t) along the Z direction relative to the inertial frame of reference, the mass M, due to its non-zero relative velocity in the frame of reference of the housing 12, is subjected to a Coriolis inertial force in this frame of reference of the case 12.

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161] Newton's second law applied to the mass M in the non-Galilean frame of reference linked to case 12 therefore takes the following form: + A LF - M1 X _ FassX 0 J . Ÿ. . F as s .Y where Fass>x and Fass>Y respectively denote the component and the resultant Fass of the forces exerted by the excitation means 45B, 45C along the X direction of the frame linked to the case 12 and following the Y direction of the reference frame linked to case 12. To simplify the writing of the equations, anisotropies are neglected in the following. damping and stiffness anisotropies, without this being limiting for the implementation of the process. Neglecting damping and stiffness anisotropies, the previous equation, After multiplication by R(-0), it can be written as follows: ■ x-(?x-28ÿ-8v m ■ 28x + 8x + ÿ-'8X Or, to put it another way: Ma, Q r • ? ... xB x-20y-6y 23X+ Bx+y-iFy x - 8y Ûx + y 0 -M Fa^ ass.y ±-0yl rj] + M Wq v to+yj + 2MQ - X F Ft assj: assx If we separate the pilot mode along the x-direction, the terms in phase or op- phase position with the position x of the mass M of the terms in quadrature with this position, by decomposing Fass>x into: F — F ass^.phase + Fass> x^quad (1 O) We obtain the following system of equations, where ABS denotes the absolute value: - 6^-2(0 + Q )y) (lia) Fass^uad^ 0 in which FasSjX phase and Fass>x>quads are the amplitudes of the terms of the component Fass>x respectively in phase and in quadrature with the position x of the mass M. Similarly, if we separate, along the y direction of the detection mode, the terms of the component Fass>y in phase or opposite phase with the position x of the mass M of the terms in quadrature with this position in:

[0162] Fass,y — Pass;y,phase + Fass,y^uad (12)

[0163] we obtain the following system of equations: 101641 | | = M( ( + 2T2).t - (S2 + )y ) (13b}

[0165] In sinusoidal steady state at resonance frequency co, if we neglect the terms that are not proportional to a positive integer power of the frequency co compared to the other terms, and taking into account that the resonance frequency co and the natural frequency co0 are close, we can write:

[0166] Fass^piwse = -2Mœ(é + (14a) * ass^quad q % F^.y.^e = ~Q^ 3' (14c) F(9 + Q))X (14d)

[0167] When the direction of the pilot mode is constant in the frame linked to the housing 12, equation 14a shows that the phase component Fass>x>phase of the force Fass>x to be exerted along the direction x of the pilot mode for the control of the mass M is zero.

[0168] Equation 14b shows that the quadrature component F^x^ of the force Fass>x is non-zero and makes it possible to combat the damping of oscillations along the x direction of the pilot mode.

[0169] Equation 14c shows that, when the amplitude of the vibrations of the mass M along the direction of the detection mode is controlled to a non-zero detection amplitude ymax, the phase component Fass> y>PhaSede of the force Fass>y to be exerted along the direction y of the detection mode for the control of the mass M is also non-zero and makes it possible to fight against the damping of the oscillations along the direction y of the detection mode.

[0170] At the relative equilibrium of the mass M in the frame of reference attached to the housing 12, if the quadrature component FasSjy>quadde of the force Fass>y is taken to be zero, then the angular velocity of rotation of the direction x of the pilot mode in the frame of reference attached to the housing 12 is the opposite of the angular velocity Q of the housing in the inertial frame of reference that we seek to measure.

[0171] II) PROCESS ACCORDING TO PRIOR ART

[0172] In the prior art method described with reference to sensor 200 shown partially in [Fig. 5], the amplitude xmax of the oscillation along the x direction of the measurement mode is equal to a non-zero constant value, the amplitude ymax of the oscillation along the y direction of the detection mode is zero and the rotating frame (x,y) is aligned with the principal axes of the ellipse described by the oscillation, thanks to four servo loops, namely an amplitude loop 210, a quadrature loop 220, a phase loop 230 and a precession loop 240.

[0173] The amplitude loop 210 is configured to calculate the Fass>x component to be exerted on the mass M along the x direction of the pilot mode for the control of its vibrations.

[0174] For this purpose, a processor of the amplitude loop 210 receives as input information on the position of the mass M along the x direction of the pilot mode from a coordinate system change module 250a, as well as information on the phase <p(t) = cot+cpode la position de masse M selon la direction x du mode pilote à la date courante t.

[0175] Information on the position of mass M along the x direction of the pilot mode is calculated by the coordinate system change module 250a from measurements of the position of mass M along the X and Y directions of the coordinate system linked to the housing 12 transmitted by a measuring module 250.

[0176] The quadrature loop 220 is configured to estimate the Fass>y component to be exerted on the mass M along the y direction of the detection mode for the control of its vibrations.

[0177] For this purpose, a quadrature loop processor 220 receives input information on the position of the mass M along the y direction of the detection mode from the measuring module 250, as well as information on the phase<p(t) = cot+q> 0 of the mass position M along the x direction of the pilot mode at the current date t.

[0178] Information on the position of mass M according to the y direction of the detection mode is calculated by the coordinate system change module 250a from the measurements of the position of mass M according to the X and Y directions of the coordinate system linked to the housing 12 transmitted by the measuring module 250.

[0179] The phase loop 230 is configured to estimate the phase<p(t) = cot+q> 0 of the mass position M along the x direction of the pilot mode at the current time t and transmit it to the processors of the amplitude loop 210 and the quadrature loop 220.

[0180] To this end, in a phase estimation step <p(t), le processeur de la boucle de phase 230 reçoit en entrée des informations sur la position de la masse M selon la direction x du mode pilote, par exemple issues de mesures de la position de la masse M selon la direction X du repère lié au boîtier 12 effectuées par le module de mesure 250.

[0181] The phase <p(t) estimée au moyen de la boucle de phase est fournie en entrée de la boucle d’amplitude 210 et de la boucle de quadrature 220.

[0182] The precession loop 240 is configured to estimate the angular position 0 of the

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192]

[0193] direction x of the pilot mode corresponding to the principal axis of the ellipse described by the oscillation. To this end, in an angular position estimation step 0, the precession loop processor 240 receives input information on the position of mass M along the x direction of the pilot mode and along the y direction of the detection mode, for example from measurements of the position of mass M along the X and Y directions of the frame linked to the housing 12. In a control step, a processor 260A of a control module 260 then receives the angular position 0, the force Fass>x and the force Fass>y thus estimated and deduces the forces Fass>x and Fass>Y to be commanded to excitation devices 260B, 260C of the mass M according to the directions X and Y of the frame linked to the housing 12. Excitation devices 260B, 260C implement this control so that the force Fass= Fass>x + Fass>Y is actually exerted. In particular, equations 14a to 14d show that if the detection amplitude ymax is zero, the resultant Fass of the forces Fass>x and Fass>Y actually exerted must be the force Fass,x,quad whose direction is the x direction of the pilot mode and in quadrature with the vibrations of the vibrating element along the x direction of the pilot mode. More precisely, | Fa.^x = F \FassJ=Fa III) PROCESS ACCORDING TO THE INVENTION In the method 100 according to the invention, the bias ^(t) is introduced into the estimation of the angular position 0(t) of the x direction of the pilot mode, so that the control module 45 receives a biased angular position 0bias(t) of this direction. Figure 7 shows a particular embodiment of the correction module 50, allowing us to understand the influence of the bias function ^(t) on the position of the rotating frame in which the first force Fass>x and the second force F ass>y are estimated with respect to the actual positions of the x direction of the pilot mode and the y direction of the detection mode. In the case of [Fig.7], the correction module 50 is placed at the output of a comparator stage 251 comprising the reference frame change module 21 and the precession module 25. The correction module 50 receives from the precession module 25 the difference ô(t) estimated between the angular position 0(t) of the pilot mode direction and the biased position 0biais (t) of the rotating frame used by the control module 45. The 50 correction module includes a 502 summing stage, configured to add cosS ass^x^uad ss^cnuad. the bias function ^(t) to the estimated difference ô(t).

[0195] The corrector module 50 finally includes a feedback loop to the comparator stage 251. The feedback loop includes the gain stage 503 and the integrator stage 504 of the corrector module 50.

[0196] The corrector module 50 is configured so that the signal supplied at the input of the comparator stage 251 converges to a zero value.

[0197] In steady state, due to the introduction of the bias function ^(t), the estimated difference ô(t) is therefore equal to the opposite of the bias function ^(t).

[0198] It is therefore understood that the biased angle 0biais differs in the process 100 from the angular position of the direction 0 of the pilot mode, unlike the prior art process.

[0199] Except for their directions, the first estimated force Fass>x and the second estimated force Fass>y are identical to those of the prior art process.

[0200] In particular, in the simplified case where the detection amplitude ymax is zero, only the FasSjXjPhase component is non-zero

[0201] Due to the introduction of the bias ^(t), the transformation matrix from the xyZ frame linked to the wave to the XYZ frame linked to the housing is a biased matrix R(0biaiS), so that the third biased force Fass>x,biaiSet the fourth biased force FasSjYjbiais controlled by the control module 40 are different from the forces Fass>x and Fass>Y of the prior art process.

[0202] By way of example, in the simplified case where the detection amplitude ymaxcst is zero, ^ass^Mais= F quad^^b^ bias “auad^^bias (

[0204] It is therefore understood that the direction of the resultant FasSjbiais of the forces exerted for the control of the vibrations of the vibrating element 15 is not the necessary direction but a biased direction, namely the biased pilot mode direction in the simplified case where the detection amplitude ymax is zero. This is shown in [Fig.2].

[0205] In other words, Fass>biais is not perfectly aligned with the x direction of pilot mode in this simplified case.

[0206] The FN component of this resultant Fass bias normal to the direction of the pilot mode xa results in the rotation of the direction of the pilot mode in the vibration plane XY, in addition to the rotation imposed by the Coriolis force.

[0207] It should be noted that the effect of introducing bias on the control of the second amplitude along the direction of the detection mode is generally negligible.

[0208] Preferably, the bias function remains permanently less than 5° in absolute value, or even less than 4°, less than 3°, less than 2°, or preferably less than 1°.

[0209] The additional angular velocity of rotation A# imposed by the introduction of the bias is known. In the simplified case where the detection amplitude ymax is zero, it is given by: [021°] (17)

[0211] The force to be exerted for the control of the second amplitude therefore becomes

[0212] (18)

[0213] The determination module 55 can therefore, at determination step 120, provide an estimator Qmes of the desired angular velocity Q based on the biased position 0 bias estimated from these measurements, as well as the bias function ^(t) and the pilot amplitude xmax. In particular, the desired angular velocity Q can be determined based on the following equation:

[0214] o (t+dt) -C 6+*)) - ((11-U0) / 1

[0215] In a particular embodiment, the bias function ^(t) is chosen to cause additional rotations of the x direction of the pilot mode by an angle a, alternately in the trigonometric and anti-trigonometric directions, the direction of rotation being changed at times f for integer i.

[0216] The angle a can be bounded in absolute value by a predetermined threshold value amax. is for example equal to ji / 2.

[0217] The instants t; can in this case be the successive instants for which the angle has reached in absolute value the predetermined threshold value amax.

[0218] The bias function can be constant and equal in absolute value to a value cons between times f and ti+i, the sign of the bias function being modified at each new date t; so as to modify the direction of the additional rotation imposed on the direction x of the pilot mode by the introduction of the bias function ^(t).

[0219] Preferably, if the bias function ^(t) is constant in absolute value, this constant absolute value being denoted , each time the sign of the bias function ^(t) is changed, therefore at each instant h, the value 0bias at the output of the correction module 50 is corrected by adding the opposite of twice the bias function at time t, that is to say -2^(ti), over an integration time step of the integrator stage 504 from time t;.

[0220] This provision makes it possible to limit the duration of the transient regime linked to the change in direction of the additional imposed rotation, the measurement of the desired angular velocity being carried out in steady state.

[0221] In particular, if we denote K as the gain of the gain stage 503 and dt as the integration time step of the integrator stage 504,

[0222]

[0223]

[0224]

[0225] / \ / \ / >+1 x with <5 ( t ) + £ =0cn steady state, i.e. S(r;+1) = -5cons / \ / \ fz'+1 / / x with ô(t}- = 0 in = <w(» w ) 4 ( «(o- established regime, i.e. = + Çœns. Adding twice ^consur the integration time step following time t i+i allows the estimated difference ô at the output of the precession module 25 to be brought more quickly to the zero value towards which it must converge at the end of the following time interval AT. The invention also relates to a computer program comprising instructions which lead the sensor 10 as described above to execute the process 100.

Claims

Demands

1. A method (100) for gyroscopic measurement using a sensor (10) comprising a housing (12) and a vibrating element (15) capable of vibrating relative to the housing (12) in a vibration plane (XY) attached to the housing (12) simultaneously along a direction (x) of a pilot mode and along a direction (y) of a detection mode different from the direction (x) of the pilot mode, the method comprising the following steps of: a) controlling (110) a first vibration amplitude of the vibrating element (15) along the direction (x) of the pilot mode to a predetermined pilot amplitude (xmax), and a second vibration amplitude of the vibrating element (15) along the direction (y) of the detection mode to a predetermined detection amplitude (ymax), and b) determining (120) an instantaneous angular velocity (Qmes) of the housing (12) with respect to a sensitive axis (Z) of the sensor (10) from measurements of the vibrations of the vibrating element (15) and of the pilot amplitude (x^),the method being characterized in that a predetermined bias (^(t)) is introduced into a measurement of an angular position (0) of the direction (x) of the pilot mode used to determine a biased force (Fass>bias) to be exerted on the vibrating element (15) for the control of the first and / or second vibration amplitude, the introduction of the predetermined bias (^(t)) causing a controlled rotation of the direction of the pilot mode (x) in the vibration plane (XY), the instantaneous angular velocity (Qmes) of the housing (12) being further determined from the predetermined bias (^(t)).

2. Method (100) of gyroscopic measurement according to claim 1, wherein the predetermined bias (^(t)) is configured to cause a rotation of the pilot mode direction by a predetermined angle (amax) alternately in a first direction and in a direction opposite to the first direction.

3. Method (100) of gyroscopic measurement according to claim 2, wherein the predetermined angle (amax) is equal to 90°.

4. Method (100) of gyroscopic measurement according to any one of the preceding claims, wherein the detection amplitude (ymax) is chosen to be zero.

5. Method (100) of gyroscopic measurement according to any one of the re- previous claims, in which the control step (110) comprises: - a measurement (1102) of the vibrations of the vibrating element (15); - an estimation (1103) of a phase ( <p(t)) caractéristique des vibrations de l’élément vibrant (15) selon la direction (x) du mode pilote à partir des résultats de la mesure (1102) ; - une première estimation (1101) d’une première force (Fass.x) dont la direction est la direction (x) du mode pilote à exercer sur l’élément vibrant (15) pour asservir la première amplitude à partir des résultats de la mesure (1102) et de la phase estimée (<p(t)) ; - une deuxième estimation (1104) d’une deuxième force (Fass.y) dont la direction est la direction (x) du mode pilote à exercer sur l’élément vibrant (15) pour asservir la deuxième amplitude à partir des résultats de la mesure (1102) et de la phase estimée (<p(t)) ; - l’introduction (1106) du biais (^(t)) prédéterminé dans les directions de la première force (Fass.x) et de la deuxième force (Fass.y) ; - the command (1107) of the biased force (Fass>biaiS) which is equal to the resultant of the first force (Fass.x) and the second force (Fass.y) after introduction of the predetermined bias (^(t)) in the directions of these two forces.

6. Method (100) of gyroscopic measurement according to claim 5, wherein the second force (Fass.y) comprises only one component (Fass>y.phase) in phase with the vibrations of the vibrating element along the direction (x) of the pilot mode.

7. Gyroscopic sensor (10) comprising a housing (12) and a vibrating element (15) capable of vibrating relative to the housing (12) in a vibration plane (XY) linked to the housing (12) simultaneously along a direction (x) of a pilot mode and along a direction (y) of a sensing mode different from the direction (x) of the pilot mode and configured to implement the steps of the process according to any one of the preceding claims.

8. Gyroscopic sensor (10) according to claim 7, comprising: - a first servo module (35), configured to estimate a first force (Fass.x) to be exerted along the direction (x) of the pilot mode to control a first vibration amplitude of the vibrating element (15) along the direction (x) of the pilot mode to a predetermined pilot amplitude (xmax); - a second servo module (40), configured to estimate

9. a second force (Fass>y) to be exerted along the direction (y) of the detection mode to control a second amplitude of vibrations of the vibrating element (15) along the direction (y) of the detection mode to a predetermined detection amplitude (ymax); - a measurement module (20), configured to generate vibration measurements of the vibrating element (15) along two directions (X,Y) of a reference frame linked to the housing (12) contained in the vibration plane (XY); - a control module (45), configured to determine a biased force (FasSjbiais) to be exerted on the vibrating element (15) for the control of the first and / or second amplitude of vibrations, from the first force (Fass>x) and the second force (Fass >y) and from a biased angular position (0biais) of the direction (x) of the pilot mode in the frame linked to the housing (12) which corresponds to an angular position (0) of the direction (x) of the pilot mode in the frame linked to the housing (12) after introduction of a predetermined bias (^(t)), and to exert the biased force (FasSjbiais); - bias means (21, 25, 30, 50), configured to provide the biased angular position (0 bias) to the control module (45) from the vibration measurements of the vibrating element (15) along the two directions (X,Y) of a frame attached to the housing (12) and the predetermined bias (^(t)), the introduction of the predetermined bias (^(t)) being configured to cause a controlled rotation of the pilot mode direction (x) in the vibration plane (XY) when the biased force is exerted (Fassbiais); and - a determination module (55), configured to determine an instantaneous angular velocity (Qmes) of the housing (12) with respect to a sensitive axis (Z) of the sensor (10) from the vibration measurements of the vibrating element (15), the pilot amplitude (xmax) and the predetermined bias (^(t)). Gyroscopic sensor according to the preceding claim, wherein the bias means (21, 25, 30, 50) comprise: - a coordinate system change module (21), configured to generate estimates of the vibrations of the vibrating element (15) according to the direction (x) of the pilot mode and the direction (y) of the detection mode from the measurements of the vibrations of the vibrating element (15) along the two directions (X,Y) of a coordinate system linked to the housing (12) provided by the measurement module (20) and the biased angular position (0 bias) provided by a correction module (50) of the bias means; - a phase module (30), configured to receive input from timations of the vibrations of the vibrating element (15) along the direction (x) of the pilot mode by the coordinate conversion module (21) and to estimate a phase ( <p(t)) caractérisant une position de l’élément vibrant (15) selon la direction (x) du mode pilote à date courante (t) ;- a precession module (25), configured to receive vibration estimates of the vibrating element (15) along the directions (x) of the pilot mode and (y) of the detection mode from the coordinate system change module (21) and the phase ( <p(t)) du module de phase (30), et pour fournir en sortie une différence estimée (ô) entre la position angulaire (0) direction (x) mode pilote dans le repère lié au boîtier (12) à date courante biaisée (0biais) fournie antérieurement par correcteur (50), et- the correction module (50), configured to provide the biased angular position (0bia;s) to the control module (45) from the estimated difference (δ), the correction module (50) comprising: (i) a summing stage (502), configured to add the predetermined bias (§(t)) to said estimated difference (ô); and ii) a feedback loop to the reference frame conversion module (21), the feedback loop comprising a gain stage (503) and an integrator stage (504), the correction module (50) being configured so that the estimated difference (ô) converges to a zero value.

10. Computer program comprising instructions that cause the sensor (10) according to any one of claims 7 to 9 to perform the method (100) according to any one of claims 1 to 6.