Gyroscope sensor and control method thereof

Abstract

A gyroscope sensor and a control method of the gyroscope sensor are provided. In a gyro sensor, a sensor unit comprising a vibrator (2) and a mounting substrate (3) having a plurality of electrodes facing the vibrator is driven and controlled by a control unit (10) having a detection gain ratio correction unit (106), a drive gain ratio correction unit (153), and an offset error correction unit (160). With the two vibration axes of the vibrator as the x axis and the y axis, the detection gain ratio correction unit corrects the gain ratio of the detection signals from the x-axis vibration and the y-axis vibration of the sensor unit, and the drive gain ratio correction unit corrects the gain ratio of the drive signals for the x-axis vibration and the y-axis vibration of the sensor unit. After the detection gain ratio and the drive gain ratio are corrected, the bias error correction unit calculates an angle at which the angular velocity calculated by the angular velocity calculation unit (132) becomes a value closest to zero, and determines the angle as the detection / drive direction of the vibration of the vibrator.

Description

Technical Field

[0001] The present disclosure relates to a gyro sensor and a control method for a gyro sensor. Background Art

[0002] Currently, a gyro sensor is known, which has an oscillator and a plurality of electrodes. The oscillator has two vibration modes with different resonant angular frequencies. The plurality of electrodes surround the oscillator, and an electrostatic force is applied to the oscillator from a part of the electrodes to vibrate it in a resonant mode, and the angular velocity applied from the outside is detected. This gyro sensor outputs a signal corresponding to the angular velocity applied from the outside based on the electrostatic capacitance between the electrodes and the oscillator, but there is also a signal output based on a zero-point error even in a state where no angular velocity is applied. Hereinafter, for convenience of explanation, the signal output from the gyro sensor in a state where no angular velocity is applied is referred to as "0-point bias output".

[0003] It is generally known that the main cause of the 0-point bias output is a component derived from the asymmetry of the oscillator. Specifically, it is due to the difference Δ(1 / τ) in the Q values of the vibration axes x and y of the oscillator and θ τ and is generated. The 0-point bias output is represented by the following formula (1).

[0004] 0-point bias output = (1 / 2η)Δ(1 / τ)sin2θ τ …(1)

[0005] In formula (1), η is a constant determined by the structure of the oscillator, called Angular gain (angular gain), τ is a time constant, and θ τ is the angle formed by the damping axis of the oscillator and the electrode axis of the electrode along which the driving and vibration detection of the oscillator are performed.

[0006] As a gyro sensor capable of reducing the 0-point bias output, for example, the gyro sensor described in Non-Patent Document 1 can be cited. The gyro sensor described in Non-Patent Document 1 reduces the 0-point bias output by adopting a method called Mode Deflection. In this method, taking Δ(1 / τ)sin2θ τ as the bias, the mode is deflected on the attenuation axis so that the bias becomes zero.

[0007] Prior Art Documents

[0008] Non-Patent Documents

[0009] Non-Patent Document 1: WANG, Peng, et al. Bias Thermal Stability Improvement of Mode-Matching MEMS Gyroscope Using Mode Deflection. Journal of Microelectromechanical Systems, 2022, 32.1: 1-3. Summary of the Invention

[0010] However, even when the above-mentioned mode is deflected on the attenuation axis, that is, when the gyroscope operates in the direction where the bias output based on θ is minimized, a residual may occur in the zero-point bias output. In the drive signal and vibration detection signal of the oscillator, when there is a gain ratio between the two vibration axes of the oscillator, a residual will occur in the zero-point bias output, and the zero-point bias output cannot be minimized. For example, a residual will occur in the zero-point bias output when the direction of the drive command issued to the oscillator is different from the actual vibration direction of the oscillator, or when the actual vibration angle of the oscillator is different from the vibration angle read according to the voltage value. τ In addition, it is also possible to consider numerically correcting the system through calibration or the like so that the zero-point bias output represented by Equation (1) becomes zero. However, since the zero-point bias output may vary due to the influence of temperature changes, aging changes, etc. under the operating state, in this case, the effect of reducing the zero-point bias output achieved through calibration or the like will be weakened. In addition, even this method, like the method described in Non-Patent Document 1, cannot cope with the case where there is a gain ratio between the two vibration axes in the detection signal and the drive signal.

[0011] In view of the above problems, an object of the present disclosure is to provide a gyroscope sensor and its control method that can reduce the influence of the gain ratio between the two vibration axes of the drive / detection signal of the oscillator and minimize the zero-point bias output.

[0012] According to one aspect of the present disclosure, a gyroscope sensor includes:

[0013] An oscillator having a first vibration mode and a second vibration mode with different resonant angular frequencies;

[0014] A mounting substrate having a plurality of electrodes facing the oscillator; and

[0015] A control unit that performs drive control of the oscillator,

[0016]

[0017] ​Define a radial direction with an imaginary straight line passing through the center of the region surrounded by multiple electrodes and along the thickness direction of the mounting substrate as the axis. Set the direction along the vibration direction of the first vibration mode as the x-axis in the radial direction, and set the direction along the vibration direction of the second vibration mode as the y-axis in the radial direction.

[0018] The control unit includes:

[0019] A first PLL that performs frequency control of a first drive signal for driving the oscillator in the first vibration mode;

[0020] A second PLL that performs frequency control of a second drive signal for driving the oscillator in the second vibration mode;

[0021] A detection gain ratio correction unit that corrects the detection gain ratio, which is the ratio of the gain of the first detection signal from the first detection electrode that detects the vibration of the oscillator on the x-axis among the multiple electrodes to the gain of the second detection signal from the second detection electrode that detects the vibration of the oscillator on the y-axis;

[0022] A drive gain ratio correction unit that corrects the drive gain ratio, which is the ratio of the gain of the first drive signal of the first drive electrode for causing the oscillator to vibrate in the first vibration mode among the multiple electrodes to the gain of the second drive signal of the second drive electrode for causing the oscillator to vibrate in the second vibration mode;

[0023] A first demodulation block that performs operations on a first demodulation output based on the first detection signal and the first drive signal and a second demodulation output based on the first detection signal and the second drive signal;

[0024] A second demodulation block that performs operations on a third demodulation output based on the second detection signal and the first drive signal and a fourth demodulation output based on the second detection signal and the second drive signal;

[0025] A first AGC that performs an operation of a drive output for maintaining the amplitude in the drive of the oscillator in the first vibration mode based on the output signal from the first demodulation block;

[0026] A second AGC that performs an operation of a drive output for maintaining the amplitude in the resonant vibration of the oscillator in the second vibration mode based on the output signal from the second demodulation block;

[0027] An angular velocity operation unit that performs an operation of the angular velocity applied from the outside; and

[0028] A bias error correction unit, which, after the detection gain ratio and the drive gain ratio are corrected, calculates an angle that makes the angular velocity calculated by the angular velocity calculation unit closest to zero, and determines this angle as the detection direction and the drive direction of the vibration of the oscillator.

[0029] In this gyro sensor, the gain ratios of the detection signals and the drive signals of the x-axis and y-axis of the oscillator are corrected by a detection gain ratio correction unit and a drive gain ratio correction unit, respectively, to reduce the influence of the gain ratios of the drive / detection signals of the oscillator on the x-axis and y-axis. In addition, after the detection gain ratio and the drive gain ratio are corrected in this gyro sensor, the angular velocity is corrected to a value closest to zero in the detection direction and the drive direction. Therefore, the zero-point bias output is minimized.

[0030] According to another aspect of the present disclosure, a control method for a gyro sensor is a control method for a gyro sensor in which an oscillator having a first vibration mode and a second vibration mode with different resonant angular frequencies is mounted on a mounting substrate having a plurality of electrodes opposed to the oscillator, and includes:

[0031] Using two PLLs to maintain the drive of the oscillator in the first vibration mode and the second vibration mode;

[0032] Defining a radial direction with an imaginary straight line passing through the center of the region surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate as an axis, setting the direction along the vibration direction of the first vibration mode as the x-axis in the radial direction, setting the direction along the vibration direction of the second vibration mode as the y-axis in the radial direction, calculating and determining a detection gain ratio, where the detection gain ratio is the ratio of the gain of the first detection signal from the first detection electrode for detecting the vibration of the oscillator on the x-axis among the plurality of electrodes to the gain of the second detection signal from the second detection electrode for detecting the vibration of the oscillator on the y-axis among the plurality of electrodes;

[0033] Calculating and determining a drive gain ratio, where the drive gain ratio is the ratio of the gain of the first drive signal from the first drive electrode for vibrating the oscillator on the x-axis among the plurality of electrodes to the gain of the second drive signal from the second drive electrode for vibrating the oscillator on the y-axis among the plurality of electrodes;

[0034] After determining the detection gain ratio and the drive gain ratio, performing an angle input scan on the detection direction and the drive direction of the vibration of the oscillator in the range of 0° to 360°, and calculating the angular velocity or the drive output for vibrating the oscillator at each input angle, and determining the value of the angular velocity closest to zero as the command value; and

[0035] Determining the detection direction and the drive direction as the angle of the command value, and measuring the angular velocity.

[0036] The control method of the gyro sensor determines the gain ratio of the detection signals on the x-axis and y-axis of the oscillator, i.e., the detection gain ratio, through calculation, and calculates and determines the gain ratio of the drive signals on the x-axis and y-axis, i.e., the drive gain ratio. Thereby, the error caused by the gain ratio of the x-axis and y-axis of the detection signal and the drive signal is reduced. Moreover, after correcting the detection gain ratio and the drive gain ratio, the control method scans the input angle in the range of 0° to 360° for the detection direction and the drive direction, determines the value with the angular velocity closest to zero as the command value, and measures the angular velocity using this command value.

[0037] Thereby, the control method of the gyro sensor can reduce the influence of the gain ratio on the x-axis and y-axis of the drive / detection signals of the oscillator, and minimize the zero-point offset output. Description of the Drawings

[0038] Figure 1 It is a perspective view showing a structural example of the sensor element.

[0039] Figure 2 It shows Figure 1 a cross-sectional view of the cross-sectional structure at the II-II line of

[0040] Figure 3 It is equivalent to Figure 2 a drawing of

[0041] Figure 4 It is an explanatory drawing regarding the vibration axis and the electrode axis of the sensor element.

[0042] Figure 5 It is a drawing showing a two-dimensional vibration model of the oscillator of the gyro sensor.

[0043] Figure 6 It is an explanatory drawing regarding the relationship between the zero-point offset output and the vibration orientation.

[0044] Figure 7 It is a block diagram showing the gyro sensor of the embodiment.

[0045] Figure 8 It is an explanatory drawing regarding the first vibration mode and the second vibration mode of the oscillator vibrating in the wine glass mode.

[0046] Figure 9 It is an explanatory drawing regarding the demodulation output calculated by the demodulation block.

[0047] Figure 10 It is a block diagram showing the operation mode of the gain ratio.

[0048] Figure 11 It is an explanatory drawing regarding the first calculation of the detection gain ratio.

[0049] Figure 12 It is an explanatory diagram of the second operation for detecting the gain ratio.

[0050] Figure 13 It is an explanatory diagram of the third operation for detecting the gain ratio.

[0051] Figure 14 It is an explanatory diagram of the operation of the drive gain ratio. Detailed implementation mode

[0052] Hereinafter, embodiments of the present disclosure will be described based on the drawings. In addition, in the following embodiments, the same or equivalent parts are denoted by the same reference numerals for description.

[0053] (First Embodiment)

[0054] The gyro sensor 1 of the first embodiment will be described with reference to the drawings.

[0055] [Basic Structure]

[0056] For example, as Figure 1 shown, the gyro sensor 1 of the present embodiment includes a sensor element having an oscillator 2 and a mounting substrate 3, and the oscillator 2 is mounted on the mounting substrate 3. The gyro sensor 1 can detect the angular velocity and the rotation angle applied to the gyro sensor 1 based on the change in the electrostatic capacitance between a part of the thin-walled oscillator 2 that can vibrate in the first vibration mode and the second vibration mode and a plurality of first electrode portions 51 in the mounting substrate 3. The gyro sensor 1 can perform control to minimize the zero-point offset output through a control unit 10 described later.

[0057] For example, as Figure 2 shown, the oscillator 2 is a minute vibrating body having a three-dimensional substantially symmetric structure including a curved surface portion 21 and a mounting portion 22. The curved surface portion 21 includes an outer shape of a substantially hemispherical three-dimensional curved surface, and the mounting portion 22 extends from the vertex side of the imaginary hemisphere formed by the curved surface portion 21 toward the center side of the hemisphere. The oscillator 2 is formed with a conductive film (not shown) on, for example, both the front and back surfaces, and a voltage can be applied from the mounting substrate 3. Further, in the oscillator 2, for example, an edge 23 on the side opposite to the mounting portion 22 in the curved surface portion 21 faces a plurality of first electrode portions 51, and the edge 23 vibrates in a resonance mode by the electrostatic force from the first electrode portions 51.

[0058] In addition, the oscillator 2 can be manufactured, for example, by preparing a plate made of an arbitrary reflow soldering material such as quartz and a mold having a bowl-shaped concave portion and a support portion at the center of the concave portion, placing the plate in the mold, and heating and softening it while reducing the pressure in the concave portion.

[0059] In addition, for example, as Figure 3As shown, the oscillator 2 may also have a substantially disc shape with a disc-shaped portion and a columnar connecting portion that joins to the mounting substrate 3 at the center of this portion. In this case, the end at the disc-shaped portion of the hollow state of the oscillator 2 is the edge 23, and this portion is surrounded by a plurality of first electrode portions 51. Thus, the oscillator 2 only needs to be structured such that it can vibrate in the first vibration mode and the second vibration mode by the drive electrodes among the plurality of first electrode portions 51. Besides the above structure, it may also be other known structures.

[0060] For example, as Figure 1 and Figure 2 shown, the mounting substrate 3 includes a lower substrate 4 and an upper substrate 5, and is a structure formed by joining them. For example, the mounting substrate 3 is obtained by performing wiring film formation, etc. on the lower substrate 4 made of borosilicate glass as an insulating material, then anodically joining the upper substrate 5 made of silicon as a semiconductor material to the lower substrate 4, and performing patterning. The mounting substrate 3 forms a plurality of first electrode portions 51 and second electrode portions 52, for example, by performing dry etching such as DRIE on the anodically joined upper substrate 5. DRIE is an abbreviation for Deep Reactive Ion Etching. Additionally, for example, when the oscillator 2 is in the Figure 2 birdbath shape shown, a circular ring-shaped groove (not shown) along the edge 23 may be formed on the lower substrate 4 as needed so as not to contact the edge 23.

[0061] The plurality of first electrode portions 51 surround the edge 23 of the oscillator 2, for example, and are arranged at equal intervals and separated from each other in a manner of depicting a ring on the plane of the mounting substrate. The plurality of first electrode portions 51 each form an electrode film (not shown) on the upper surface. The plurality of first electrode portions 51 can control their potentials, for example, by connecting wires (not shown) to the electrode films (not shown) and electrically connecting them to an external circuit board or the like. The plurality of first electrode portions 51 are all in a state of being separated from the edge 23 of the oscillator 2 by a predetermined distance, and form capacitors with the oscillator 2 respectively, and can detect the electrostatic capacitance with the oscillator 2. A part of the plurality of first electrode portions 51 are detection electrodes for detecting the electrostatic capacitance, and the other part are drive electrodes for applying an electrostatic force to the edge 23 of the oscillator 2.

[0062] For example, as Figure 1 shown, the second electrode portion 52 has a frame shape surrounding the plurality of first electrode portions 51, forms an electrode film (not shown) on the upper surface, and connects wires (not shown) to the electrode film (not shown). The second electrode portion 52 is connected to a conductive film (not shown) of the oscillator 2 through wirings (not shown) or the like, and is configured to be able to apply a voltage.

[0063] The above is the basic structure of the sensor element in the gyro sensor 1 of this embodiment. The control unit 10 that performs the drive control of the gyro sensor 1 will be described later.

[0064] In addition, in Figure 1 , as a representative example, a case where the mounting substrate 3 has 16 first electrode portions 51 and one frame-shaped second electrode portion 52 is shown, but it is not limited thereto. For example, the mounting substrate 3 may appropriately change the number, arrangement, shape, etc. of the first electrode portion 51 and the second electrode portion 52.

[0065] [Vibration model and zero-point offset output]

[0066] Next, the vibration model and zero-point offset output of the oscillator 2 will be described.

[0067] When the oscillator 2 is observed from the normal direction with respect to the plane direction formed by the mounting substrate 3 (hereinafter referred to as "top view observation"), by applying a voltage to a part of the first electrode portion 51, for example, as Figure 4 shown, it becomes a resonant state in which the number of antinodes and nodes of the vibration amplitude of the outer contour of the edge 23 is 2n each. n is an integer of 2 or more, and such a resonant state of the oscillator 2 is called a "wine-glass mode". In addition, in Figure 4 , the state shown as a representative example is the resonant mode of n = 2 in the wine-glass mode, and the vibration axes x and y and the electrode axes X and Y described later coincide, but the oscillator 2 may also vibrate in a higher-order wine-glass mode of n = 3 or more.

[0068] Hereinafter, for the sake of convenience of explanation, as Figure 4 shown, with the center position of the edge 23 at the time of top view observation as the center C, the radial direction with the straight line along the thickness direction of the mounting substrate 3 passing through the center C as the axis is called the "substrate radial direction", and the circumferential direction with this straight line as the axis is called the "substrate circumferential direction". In addition, the direction passing through the antinode position of the vibration at the edge 23 of the oscillator 2 in the first vibration mode (resonant angular frequency ω1) in the direction along the substrate radial direction is called the "vibration axis x", and the direction passing through the node position is called the "vibration axis y". At this time, in the wine-glass mode of n = k (k: an integer of 2 or more), the angle formed by the vibration axis x and the vibration axis y is (360 / 4k)°. For example, in the wine-glass mode of n = 2, the angle formed by the vibration axis x and the vibration axis y is 45°.

[0069] The plurality of first electrode portions 51 are arranged separately from each other along the substrate circumferential direction, and are arranged in such a way that the distance from the edge 23 in the non-vibrating state is substantially the same. Here, for the sake of convenience of explanation, for example, as Figure 4 shown, one direction on the actual plane where the plurality of first electrode portions 51 are arranged is set as "X r"direction", the direction orthogonal to the X-axis on this plane is set as "Y r direction", and this plane is set as "X r Y r Y r plane". Moreover, a direction on the X r Y r Y plane is defined as "electrode axis X", and the direction when the electrode axis X is rotated counterclockwise by (360 / 4k)° along the circumferential direction of the substrate on the X r Y r Y plane is defined as "electrode axis Y".

[0070] For example, as Figure 5 shown, the oscillator 2 has two springs with spring constants k x , k y along its vibration direction and two objects with damping coefficients C x , C y connected, and can be regarded as a vibrating body of a two-degree-of-freedom system vibrating in a two-dimensional plane. Figure 5 represents converting the vibration axes x, y and the electrode axes X, Y on the X r Y r Y plane into an orthogonal coordinate system respectively, and making the origins of the vibration axes x, y and the electrode axes X, Y coincide. Hereinafter, the vibration axes x, y are sometimes simply referred to as the x-axis, y-axis.

[0071] In addition, the two-dimensional plane mentioned here refers to the plane along the surface of the mounting substrate 3 where a plurality of first electrode portions 51 are formed. The spring constants k x , k y are the spring constants on the vibration axes x, y respectively, and the damping coefficients C x , C y are the damping coefficients of the vibrations on the vibration axes x, y respectively. The angle θ ω is the angle formed by the electrode axes X, Y and the vibration axes x, y as the spring axes, and the angle θ τ is the angle formed by the electrode axes X, Y and the damping axis along the direction of vibration attenuation. The sensor element composed of the oscillator 2 and the mounting substrate 3 is usually θ ω ≠0 without performing special processing or the like.

[0072] Here, Figure 5 the equation of motion of the vibration model of the two-degree-of-freedom system shown is expressed by the following equation (2).

[0073]

Mathematical formula 1

[0074]

[0075] In formula (2), ω is the resonant angular frequency of the vibrator 2, and Δω is the absolute value of the difference between the resonant angular frequencies of the first vibration mode and the second vibration mode when they are set to ω1 and ω2. Although the zero-point bias output is expressed as formula (1) as described above, it is obtained by formula (2). The zero-point bias output depends more on Δ(1 / τ) which is the Q value difference between the vibration axes x and y, and θ τ . In addition, Δ(1 / τ) and τ are expressed by the following equations (3) and (4).

[0076] Δ(1 / τ)=(1 / τ x )-(1 / τ y )…(3)

[0077] τ=1 / (ζω)=2Q / ω n =Q / πf…(4)

[0078] (3) where τ x , τ y is the time constant on the x-axis and y-axis.

[0079] (4) where ζ is the attenuation ratio, ω n is the natural angular frequency.

[0080] When the 0-point bias output is based on the equation (1) with the vibration direction of the vibrator 2 as the horizontal axis and the vertical axis as the 0-point bias output, for example Figure 6 As shown in FIG. 1 , the waveform becomes a sine wave. That is, the vibration direction where the 0-point bias output is zero is set to θ0, and by making θ τ Adjust θ to achieve θ0 τ , the 0-point bias output will become the minimum. The gyro sensor 1 controls the vibration direction as described above, based on correcting the gain ratio of the x-axis and y-axis of the detection signal from the sensor unit composed of the vibrator 2 and the mounting substrate 3 and the gain ratio of the x-axis and y-axis of the drive signal of the sensor unit, so as to minimize the 0-point bias output. For details, see below. In addition, the sensor unit refers to a part composed of a sensor element including the vibrator 2 and the mounting substrate 3 and a current-voltage conversion circuit for applying voltage to the plurality of first electrode units 51, which is not shown in the figure.

[0081] [Control Department]

[0082] Next, the control unit 10 of the gyro sensor 1 will be described.

[0083] For example Figure 7As shown, the control unit 10 includes detection circuits 101 and 102 that detect vibrations in the x-axis and y-axis of the oscillator 2, and ADCs 103 and 104 that convert the analog signals of the detection circuits 101 and 102 into digital signals. ADC is an abbreviation for Analog to Digital Converter. For example, the detection circuit 101 detects signals from the detection electrodes that detect vibrations in the x-axis among the plurality of first electrode portions 51. The detection circuit 102 detects signals from the detection electrodes that detect vibrations in the y-axis among the plurality of first electrode portions 51. The ADC 103 converts the analog signal from the detection circuit 101 into a digital signal. The ADC 104 converts the analog signal from the detection circuit 102 into a digital signal.

[0084] For example, the control unit 10 includes a detection direction correction unit 105, a detection gain ratio correction unit 106, a first demodulation block 110, and a second demodulation block 120 that are input with signals from the ADCs 103 and 104.

[0085] The detection direction correction unit 105 corrects the detection directions of vibrations in the x-axis and y-axis, for example, based on an input signal from a bias error correction unit 160 described later. After the detection gain ratio and the drive gain ratio are corrected, the detection direction correction unit 105 performs a process of correcting the detection direction of vibration to the vibration orientation θ0 with the minimum zero-point offset output.

[0086] The detection gain ratio correction unit 106 corrects the gain ratio of the detection signals in the x-axis and y-axis, that is, the detection gain ratio, for example, based on information from the demodulation blocks 110 and 120 when the AGCs 130, 131, PLLs 140, and 141 described later are operating. The detection gain ratio calculated by the detection gain ratio correction unit 106 or the demodulation output calculation unit 113 is used to calculate the vibration orientation with the minimum zero-point offset output. The calculation of the detection gain ratio will be described later.

[0087] The first demodulation block 110 calculates the demodulation output related to the vibration axis x, for example, based on an input signal from the detection gain ratio correction unit 106. In addition, the first demodulation block 110 outputs an amplitude component in phase with the frequency signal and an amplitude component with a phase shifted by 90° from the frequency signal, for example, based on the frequency signal related to the vibration axis x from the PLL 140 described later. The first demodulation block 110 includes, for example, a first demodulation unit 111, a second demodulation unit 112, and a demodulation output calculation unit 113.

[0088] The first demodulation unit 111 calculates the demodulation outputs V Xβ , V Xi1 , V Xq1 . The demodulation output VXi1 , V Xq1 perform operations respectively based on the detection signals of the detection electrodes from the x-axis, and are the demodulation outputs in-phase (InPhase) with the drive signal of the resonance angular frequency ω1 of the first vibration mode and the demodulation outputs in quadrature phase with the drive signal. The second demodulation unit 112, for example, calculates the demodulation outputs V Xβ based on the second drive signal for driving the oscillator 2 in the second vibration mode with the resonance angular frequency ω2 and the processing signal V Xi2 , V Xq2 . In a system where the resonance angular frequencies ω1 and ω2 of the oscillator 2 are maintained by two independent PLLs 140 and 141 described later, the processing signal V Xβ contains information about the vibration amplitude in the vibration axis y direction of the second vibration mode, so this is achievable. The demodulation outputs V Xi2 , V Xq2 perform operations respectively based on the detection signals of the detection electrodes from the x-axis, and are the demodulation outputs in-phase (In Phase) with the drive signal of the resonance angular frequency ω2 of the second vibration mode and the demodulation outputs in quadrature phase with the drive signal. The demodulation output operation unit 113, for example, calculates the amplitude and phase of the first vibration mode of the oscillator 2 based on V Xi1 , V Xq1 , V Xi2 , V Xq2 .

[0089] The second demodulation block 120, for example, calculates the demodulation output related to the vibration axis y based on the input signal from the detection gain ratio correction unit 106. In addition, the second demodulation block 120, for example, outputs the amplitude component in-phase with the frequency signal related to the vibration axis y from the PLL 141 described later and the amplitude component with a phase shifted by 90° from the frequency signal based on the frequency signal related to the vibration axis y. The second demodulation block 120, for example, includes a first demodulation unit 121, a second demodulation unit 122, and a demodulation output operation unit 123.

[0090] The first demodulation unit 121, for example, calculates the demodulation outputs V Yβ based on the above-mentioned second drive signal and the processing signal V Yi2 , V Yq2 . The demodulation outputs V Yi2 , V Yq2 perform operations respectively based on the detection signals of the detection electrodes from the y-axis, and are the demodulation outputs in-phase (In Phase) with the frequency signal of the resonance angular frequency ω2 of the second vibration mode and the demodulation outputs in quadrature phase with the drive signal. The second demodulation unit 122, for example, calculates the demodulation output V Yβ based on the above-mentioned first drive signal and the processing signal VYi1 and V Yq1 。Similar to the above, since the processing signal V Yβ contains information about the vibration amplitude in the x - direction of the vibration axis of the first vibration mode, this demodulation by the second demodulation unit 122 is achievable. The demodulation output V Yi1 and V Yq1 For example, operations are respectively performed based on the detection signals from the detection electrodes on the y - axis, and are demodulation outputs in - phase with the frequency signal of the resonance angular frequency ω1 of the first vibration mode and demodulation outputs in quadrature with the drive signal. The demodulation output operation unit 113, for example, based on V Yi1 and V Yq1 and V Yi2 and V Yq2 calculates the amplitude and phase of the second vibration mode of the oscillator 2. In addition, the operations of the above - mentioned respective demodulation outputs will be described later.

[0091] The control unit 10 includes an AGC 130 and a PLL 140 for resonantly driving the oscillator 2 in the first vibration mode and maintaining it, and an AGC 131 and a PLL 141 for resonantly driving the oscillator 2 in the second vibration mode and maintaining it. AGC is the abbreviation of Automatic Gain Control and is also called automatic gain control. PLL is the abbreviation of Phase - Locked Loop and is also called phase - locked loop.

[0092] The AGC 130 is, for example, input with the amplitude information in the x - direction of the vibration axis of the first vibration mode of the oscillator 2 from the first demodulation block 110, and performs operations and signal outputs for controlling the amplitude in the first vibration mode to a specified constant value based on this amplitude information. The AGC 130, for example, outputs a control signal for fixing the amplitude to the modulation unit 151 and outputs a signal for calculating the angular velocity to the angular velocity calculation unit 132.

[0093] The AGC 131 is, for example, input with the amplitude information in the y - direction of the vibration axis of the second vibration mode of the oscillator 2 from the second demodulation block 120, and performs operations and signal outputs for controlling the amplitude in the second vibration mode to a specified constant value based on this amplitude information. The AGC 131, for example, outputs a control signal for fixing the amplitude to the modulation unit 152 and outputs a signal for calculating the angular velocity to the angular velocity calculation unit 132.

[0094] The angular velocity calculation unit 132, for example, based on the input signals V Ω+ and V Ω－, the angular velocity applied externally to the gyro sensor 1 is calculated by dividing the value obtained by subtracting these signals by a pre-measured scale factor. In addition, for example, when determining the vibration orientation for minimizing the zero-point offset output, the angular velocity calculation unit 132 calculates the angular velocity at each angular input of the bias error correction unit 160 described later.

[0095] The PLL 140 is input, for example, with the phase information of the first vibration mode of the oscillator 2 from the first demodulation block 110, and performs frequency control and signal output of the first drive signal for driving the oscillator 2 in the first vibration mode at the resonance angular frequency ω1. The PLL 140 includes, for example, a PI circuit and an NCO circuit (not shown). The PI circuit corrects the demodulated output V Xq1 of the signal, and the NCO circuit outputs a first drive signal of a specified frequency based on the corrected signal. PI is an abbreviation for Proportional Integral. NCO is an abbreviation for Numerically Controlled Oscillator, which generates signals of frequencies such as sine waves and cosine waves and is also called a numerically controlled oscillator. The PLL 140 outputs signals to the demodulation blocks 110, 120, and the modulation unit 151.

[0096] The PLL 141 is input, for example, with the phase information of the second vibration mode of the oscillator 2 from the second demodulation block 120, and performs frequency control and signal output of the second drive signal for driving the oscillator 2 in the second vibration mode at the resonance angular frequency ω2. The PLL 141 has, for example, the same structure as the PLL 140. The PI circuit corrects the demodulated output V Yq2 of the signal, and the NCO circuit outputs a second drive signal of a specified frequency based on the corrected signal. The PLL 141 outputs signals to the demodulation blocks 110, 120, and the modulation unit 152.

[0097] The control unit 10 includes, for example, a modulation unit 151 that is input with the output signals from the AGC 130 and the PLL 140, and a modulation unit 152 that is input with the output signals from the AGC 131 and the PLL 141.

[0098] The modulation unit 151, for example, superimposes the frequency signal from the PLL 140 and the amplitude control signal input from the AGC 130, and outputs the superimposed signal to the drive gain ratio correction unit 153. The modulation unit 152, for example, superimposes the frequency signal from the PLL 141 and the amplitude control signal input from the AGC 131, and outputs the superimposed signal to the drive gain ratio correction unit 153.

[0099] The control unit 10 includes, for example, a drive gain ratio correction unit 153, a drive direction correction unit 154, DACs 155, 156, and drive circuits 157, 158.

[0100] The drive gain ratio correction unit 153 calculates the gain ratio of the drive signals for the x-axis and y-axis, i.e., the drive gain ratio, based on the input signals from the modulation units 151 and 152 when the AGCs 130, 131, PLLs 140, and 141 are operating. The drive gain ratio calculated by the drive gain ratio correction unit 153 is used together with the detection gain ratio to calculate the vibration orientation with the minimum zero-point offset output. The calculation of the drive gain ratio will be described later.

[0101] The drive direction correction unit 154 corrects the vibration directions of the x-axis and y-axis, for example, based on the input signal from the bias error correction unit 160. The drive direction correction unit 154 performs a process of correcting the drive direction to the vibration orientation θ0 calculated after correcting the detection gain ratio and the drive gain ratio.

[0102] The DACs 155 and 156 convert, for example, the digital signals for driving control of the oscillator 2 input from the drive direction correction unit 154 into analog signals and output them to the drive circuits 157 and 158 respectively. DAC is an abbreviation for Digital to Analog Converter.

[0103] The drive circuits 157 and 158 output drive signals related to the x-axis and y-axis to the drive electrodes in the plurality of first electrode portions 51, for example, to vibrate the oscillator 2 in the resonant mode. Thus, for the oscillator 2, a force F generated by electrostatic force acts on it in the x-axis x , and a force F generated by electrostatic force acts on it in the y-axis y , to perform vibration control.

[0104] The bias error correction unit 160 calculates, for example, the vibration orientation θ0 with the minimum zero-point offset output after the detection gain ratio and the drive gain ratio are corrected, and outputs an instruction signal corresponding to the calculated vibration orientation θ0 to the detection direction correction unit 105 and the drive direction correction unit 154. The calculation of the vibration orientation θ0 by the bias error correction unit 160 will be described later.

[0105] The above is the basic structure of the control unit 10. In addition, the control unit 10 is not limited to Figure 7 the example shown, and the structure can be appropriately changed as long as it can perform control to minimize the zero-point offset output.

[0106] For example, the control unit 10 may also have a structure in which the positions of the detection direction correction unit 105 and the detection gain ratio correction unit 106 are reversed, that is, the detection gain ratio is calculated before the detection direction correction is calculated. For example, the control unit 10 may also have a structure in which the positions of the drive direction correction unit 154 and the drive gain ratio correction unit 153 are reversed, that is, the drive gain ratio is calculated after the drive direction correction is calculated. The control unit 10 may also have a structure, for example, in which the gyroscope operates in an open-loop manner without feeding back the information in the y direction input to the second demodulation block 120. In this case, for example, the control unit 10 has a structure in which the signals from the demodulation blocks 110 and 120 are directly input to the angular velocity calculation unit 132. In addition, the control unit 10 may also have a structure, for example, that performs FtR control, that is, feeds back the information in the y direction input to the second demodulation block 120 to control the amplitude in the y direction to 0, and calculates the angular velocity based on the control voltage at this time. In addition, FtR is an abbreviation for Force to Rebalance. In this way, the control unit 10 can appropriately change a part of its components.

[0107] [Operations in the Demodulation Block]

[0108] Next, the operations of the demodulation outputs in the demodulation blocks 110 and 120 will be described.

[0109] When the oscillator 2 is driven in both the first vibration mode and the second vibration mode of the resonance mode with n = 2, for example, as Figure 8 shown, it vibrates along two orthogonal vibration axes x and y. Moreover, let the vibration amplitude and the resonance angular frequency on the vibration axis x be A and ω1, respectively, let the vibration amplitude and the resonance angular frequency on the vibration axis y be B and ω2, respectively, and let the angle formed by the vibration axis x and the electrode axis X be θ ω . At this time, the vibration amplitudes of the vibration axes x and y at time t are represented by the following equations (5) and (6).

[0110] x = A sin(ω1t + φ1) · · · (5)

[0111] y = B sin(ω2t + φ2) ··· (6)

[0112] φ1 in equation (5) and φ2 in equation (6) are the phases with respect to the external forces applied from each direction. If the components of the vibration with amplitude A on the electrode axes X and Y are set as a X , a Y , and the components of the vibration with amplitude B on the electrode axes X and Y are set as b X , b Y , then the offset angle θ ω between the vibration axis x and the electrode axis X is represented by the following equation (7) according to the orthogonality of the vibration axes x and y.

[0113]

Mathematical Formula 2

[0114]

[0115] In addition, the conversion between the electrode axes X and Y and the vibration axes x and y is represented by the following equation (8).

[0116]

Mathematical Formula 3

[0117]

[0118] In addition, since the sum of the X components of the two vibration modes is on the electrode axis X and the sum of the Y components of the two vibration modes is on the electrode axis Y, the vibration amplitudes of the electrode axes X and Y at time t are represented by the following equations (9) and (10).

[0119] X = a X sin(ω1t + φ1) + b X sin(ω2t + φ2) ··· (9)

[0120] Y = a Y sin(ω1t + φ1) + b Y sin(ω2t + φ2) ··· (10)

[0121] Furthermore, in Figure 8 the example shown, the respective components a X , b X , a Y , b Y in equations (9) and (10) are respectively a X = Acosθ ω , b X = -Bsinθ ω , a Y = Asinθ ω , b Y = Bcosθ ω . In addition, if the conversion coefficients from the amplitude to the voltage corresponding to the detection method are set to ξ X , ξ Y , then the voltages V XP , V YP on the detection electrodes of the electrode axes X and Y respectively are represented by the following equations (11) and (12).

[0122] V XP = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)} ··· (11)

[0123] V YP = ξ Y {a Y sin(ω1t + φ1) + b Y sin(ω2t + φ2)} ··· (12)

[0124] The first demodulation unit 111 demodulates and outputs V for the external forces on the vibration axes x and y based on the voltage V in Equation (11). XP , and performs operations on the demodulation outputs V Xi1 , V Xq1 . The demodulation output V Xi1 is calculated by multiplying the voltage V XP by sinω1t as shown in Equation (13) below, and eliminating the terms of the second harmonic and the sum of frequencies through a low-pass filter as shown in Equation (14).

[0125]

Mathematical formula 4

[0126]

[0127]

Mathematical formula 5

[0128] V Xi1 = |2V XP sinω1t| LPF

[0129] = ξ X {a X cosφ1 + b X (cosφ2cos△ωt - sinφ2sin△ωt)} = ξ X {a X cosφ1 + b X cos(△ωt + φ2)} … (14)

[0130] |f(t)| in Equation (14) LPF refers to the operation of eliminating the terms of the second harmonic and the sum of frequencies through the above-mentioned low-pass filter. The same applies to Equations (16), (18), and (20) hereafter.

[0131] The demodulation output V Xq1 is calculated by multiplying the voltage V XP by cosω1t as shown in Equation (15) below, and eliminating the unnecessary terms through a low-pass filter as shown in Equation (16).

[0132]

Mathematical formula 6

[0133]

[0134]

Mathematical formula 7

[0135] V Xq1 = |2V XP cosω1t| LPF

[0136] = ξ X {a X sinφ1 + b X (cosφ2cos△ωt - sinφ2cos△ωt)}

[0137] = ξ X {a X sinφ1 + b X sin(△ωt + φ2)}…(16)

[0138] The second demodulation unit 112 demodulates and outputs V XP for the external forces on the vibration axes x and y based on the voltage V in equation (11). Xi2 V Xq2 The second demodulation unit 112, for example, obtains a frequency signal for driving the oscillator 2 in the second vibration mode at the resonance angular frequency ω2 from the PLL 141, and performs the operation of demodulation output V Xi2 V Xq2 The demodulation output V Xi2 is calculated by performing a process of multiplying the voltage V XP by sin(ω2t + Δφ) as shown in the following equation (17), and eliminating unnecessary terms through a low-pass filter as shown in equation (18). In addition, Δφ is, for example, the phase of the output signal of an oscillation circuit (not shown) in the PLL 140 with respect to the output signal of an oscillation circuit (not shown) in the PLL 140 as a reference.

[0139] V XP sin(ω2t + △φ) = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)}sin(ω2t + △φ)…(17)

[0140]

Mathematical formula 8

[0141] V Xi2 = |2V XP sin(ω2t + △φ)| LPF

[0142] = ξ X {b X cos(φ2 - △φ) + a X cos(△ωt - φ1 + △φ)}…(18)

[0143] Demodulation output V Xq2 By performing the process of multiplying the voltage V as shown in the following equation (19): XP by cos(ω2t + Δφ), and calculating through the operation of eliminating unnecessary terms by a low-pass filter as shown in equation (20).

[0144] V XP cos(ω2t + △φ) = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)}cos(ω2t + △φ)…(19)

[0145]

Mathematical formula 9

[0146] V Xq2 =|2V XP cos(ω2t + △φ)| LPF

[0147] =ξ X {b X sin(φ2 - △φ) + a X sin(△ωt - φ1 + △φ)}…(20)

[0148] The first demodulation unit 121 performs the operation of the demodulation output V for the external forces on the vibration axes x and y based on the detected voltage V in equation (12). YP , and calculates the demodulation output V Yi2 , V Yq2 . The second demodulation unit 122, for example, obtains a frequency signal for driving the oscillator 2 in the second vibration mode at the resonance angular frequency ω1 from the PLL 140, and performs the operation of the demodulation output V Yi1 , V Yq1 . The demodulation output V YP , V Yi1 , V Yq1 , V Yi2 , V Yq2 is calculated through the same arithmetic processing as the above V Xi1 , V Xq1 , V Xi2 , V Xq2 and is represented by the equations shown by Figure 9 . When φ1 = φ2 = Δφ = 0 is satisfied, these demodulation outputs can be deformed into mathematical formulas without the terms of φ1, φ2, and Δφ.

[0149] Demodulation output V Xi1 , V Xq1 , V Xi2 , V Xq2 , V Yi1 , V Yq1 , VYi2 , V Yq2 For example, it is output to the demodulation output arithmetic units 113, 123, etc., and is used for the arithmetic operation of the amplitudes of the first vibration mode and the second vibration mode and the calculation of the phase difference. Hereinafter, for the sake of convenience of explanation, the demodulation output V Xi1 , V Xq1 , V Xi2 , V Xq2 , V Yi1 , V Yq1 , V Yi2 , V Yq2 are collectively referred to as "each demodulation output".

[0150] For example, the demodulation output arithmetic units 113, 123 have a structure including a high-pass filter (hereinafter referred to as "HPF"), an arithmetic unit that performs arithmetic operations using each demodulation output after passing through the HPF, and a phase comparison unit that calculates the phase difference of each demodulation output.

[0151] The demodulation output arithmetic unit 113, for example, operates |ξ Xi1 , V Xq1 | by performing a sum-of-squares operation in which the squares of the demodulation outputs V X b X | after passing through the HPF are respectively squared and added by the arithmetic unit. The demodulation output arithmetic unit 113, for example, operates |ξ Xi2 , V Xq2 | by performing a sum-of-squares operation based on the demodulation outputs V X a X | after passing through the HPF by the arithmetic unit. In addition, the demodulation output arithmetic unit 113, for example, calculates the phase difference Δφ Xi1 , V Xi2 based on the demodulation outputs V Xi after passing through the HPF, and calculates the phase difference Δφ Xq1 , V Xq2 based on the demodulation outputs V Xq .

[0152] The demodulation output arithmetic unit 123, for example, operates |ξ Yi1 , V Yq1 | by performing a sum-of-squares operation based on the demodulation outputs V Y b Y | through the same processing as the demodulation output arithmetic unit 113, and operates |ξ Yi2 , V Yq2 | by performing a sum-of-squares operation based on the demodulation outputs V Y a Y |. In addition, the demodulation output arithmetic unit 123, for example, is the same as the demodulation output arithmetic unit 113, and calculates the phase difference Δφ Yi1 , V Yi2 based on the demodulation outputs VYi , based on V Yq1 , V Yq2 to calculate the phase difference Δφ Yq .

[0153] Demodulation blocks 110, 120 can, for example, obtain the amplitude information of the resonant mode through the above operations of |ξ X a X |, |ξ Y a Y |, |ξ X b X |, |ξ Y b Y |, and obtain the phase information of the resonant mode through the above operations of the phase difference Δφ Xi , Δφ Xq , Δφ Yi , Δφ Yq . Hereinafter, for the sake of convenience of explanation, the above operations of |ξ X a X |, |ξ Y a Y |, |ξ X b X |, |ξ Y b Y | for calculating the amplitude are simply referred to as "amplitude operations".

[0154] [Detection gain ratio, drive gain ratio, and reduction of zero-point bias output]

[0155] Next, the detection gain ratio and the drive gain ratio will be described.

[0156] In Figure 7 the system shown for inputting a driving force to the oscillator 2, the ratio of the non-ideal gains of the x-axis and the y-axis is considered as G pxy and the case where it exists is explored. Hereinafter, this non-ideal gain ratio is referred to as the detection gain ratio G pxy . In this case, the voltages input to each axis are set as V x , V y , and the vibration information x, y of the oscillator 2 is expressed by the following equation (21) through the voltages V x , V y and the detection gain ratio G pxy .

[0157] [Mathematical formula 10]

[0158]

[0159] To cancel the non-ideal detection gain ratio G pxy in equation (21), as long as the detection gain ratio G is calculated by some meanspxy , and the determinant of the following formula (22) can be multiplied by formula (21).

[0160]

Mathematical formula 11

[0161]

[0162] For example, the detection gain ratio correction unit 106 performs matrix operations of multiplying the determinant of formula (22), that is, a matrix containing the reciprocal of the detection gain ratio, 1 / G pxy by the determinant of the detection signal obtained via the detection circuits 101 and 102 shown in formula (21). When the control unit 10 calculates the detection gain ratio and the drive gain ratio, for example, as Figure 10 shown, the gain ratio calculation process is performed in an operation mode that does not perform the processing of a part of the components shown in Figure 7 . In addition, in Figure 10 , for ease of observation, a part of the components that are not used in the angular velocity calculation and the gain ratio calculation is omitted.

[0163] In each gain ratio operation mode, in the control unit 10, the detection signals of the vibrations of the x and y axes from the sensor unit are input to the demodulation blocks 110 and 120 via the detection circuits 101, 102 and the ADCs 103, 104, and various demodulation outputs and amplitude calculations based on the various demodulation outputs are performed. In addition, the demodulation outputs V Xq1 , V Yq2 are used for the calculation of the detection gain ratio G pxy . The detection gain ratio G pxy calculated in the gain ratio operation mode is, for example, stored in a recording medium (not shown) held in the control unit 10, and then read from the recording medium and used in the angular velocity operation mode for calculating the angular velocity. The same applies to the drive gain ratio G fxy described later.

[0164] The calculation of the detection gain ratio G pxy is performed in a state where no angular velocity input is applied to the sensor unit, that is, in an offline state. The detection gain ratio G pxy is represented by the following formula (23).

[0165]

Mathematical formula 12

[0166]

[0167] D in formula (23) x , D y are, for example, calculated values obtained by the operations shown in Figure 11 , Figure 12 . Specifically, for example, as Figure 11As shown, the first demodulation block 110 performs amplitude operations based on the demodulation output V Xi1 and amplitude operations based on the demodulation output V Xq1 to calculate a first addition value obtained by adding the two values obtained in each amplitude operation. Additionally, for example, the first demodulation block 110 performs amplitude operations based on the demodulation output V Xi2 and amplitude operations based on the demodulation output V Xq2 to calculate a second addition value obtained by adding the two values obtained in each amplitude operation. For example, the first demodulation block 110 calculates the operation value D x by multiplying the first addition value by the second addition value.

[0168] For example, as Figure 12 shown, the second demodulation block 120 performs amplitude operations based on the demodulation outputs V Yi1 and V Yq1 respectively, and adds the two obtained values to calculate a third addition value. Additionally, for example, the second demodulation block 120 performs amplitude operations based on the demodulation outputs V Yi2 and V Yq2 respectively, and adds the two values obtained in each amplitude operation to calculate a fourth addition value. Then, the third and fourth addition values are multiplied to calculate the operation value D y .

[0169] Then, the detection gain ratio correction unit 106, for example, as Figure 13 shown, performs an operation of taking the square root of the value obtained by dividing the calculated operation value D x by the operation value D y to calculate the detection gain ratio G pxy . Then, the detection gain ratio correction unit 106 calculates the detection gain ratio correction value shown in equation (22) based on the detection gain ratio G pxy and corrects the detection gain ratio by multiplying it by equation (21).

[0170] Next, in a system where driving forces F x and F y are input to the oscillator 2, the case where the ratio of the non-ideal gains of the driving forces F x and F y exists as G fxy is discussed. Hereinafter, the non-ideal gain ratio of these two driving forces F x and F y is called the drive gain ratio G fxy . Let the output signal from the DAC 155 on the x-axis and the output signal from the DAC 156 on the y-axis be V Fx and V Fy, the driving force F applied to the oscillator 2 based on the driving signals from the driving circuits 157 and 158 x , F y includes the driving gain ratio G fxy is represented by the following equation (24).

[0171] [Mathematical formula 13]

[0172]

[0173] In order to cancel the non-ideal driving gain ratio G in equation (24) fxy , it is only necessary to calculate the driving gain ratio G by some means fxy , and multiply the determinant of equation (24) by the determinant of the following equation (25).

[0174] [Mathematical formula 14]

[0175]

[0176] For example, the driving gain ratio correction unit 153 performs a matrix operation of multiplying the determinant of equation (25), that is, the matrix including the reciprocal of the driving gain ratio 1 / G fxy by the determinant of equation (24). The operation of the driving gain ratio G fxy is the same as the operation of detecting the gain ratio G pxy , and is performed in an offline state. The driving gain ratio G fxy is represented by the following equation (26).

[0177] [Mathematical formula 15]

[0178]

[0179] For example, as Figure 14 shown, the driving gain ratio correction unit 153 calculates the driving gain ratio G x , Q x , AGC y , Q y and the driving gain ratio correction value. AGC fxy x is the AGC output related to the driving force F on the x-axis output from the AGC 130 to the modulation unit 151 x , and AGC y is the AGC output related to the driving force F on the y-axis output from the AGC 131 to the modulation unit 152 y . Q x , Q y ​They are respectively the Q value of the vibration of the vibrator 2 on the x-axis and the Q value of the vibration of the vibrator 2 on the y-axis, which are pre-calculated by a known Q value measurement method and recorded in a recording medium (not shown). The drive gain ratio correction unit 153 calculates the first multiplication value obtained by multiplying with Q x and Q x and the second multiplication value obtained by multiplying with Q y and Q y and calculates the drive gain ratio G by a division operation of dividing the first multiplication value by the second multiplication value fxy . Then, the drive gain ratio correction unit 153 calculates the drive gain ratio correction value represented by equation (25) based on the drive gain ratio G fxy and corrects the drive gain ratio by multiplying it with equation (24).

[0180] Finally, after correcting the detection gain ratio and the drive gain ratio, the control unit 10 drives the vibrator 2 in a resonant mode in a stationary state without applying an angular velocity to the gyro sensor 1 to perform a gyro operation. The bias error correction unit 160 inputs an angle to the detection direction correction unit 105 and the drive direction correction unit 154 in the range of 0° to 360° to rotate the gyro operation axis by 360°. At this time, the bias error correction unit 160 scans the input angle at an arbitrary angle step and an arbitrary drive time, for example, and records the angular velocity or the drive output of the AGCs 130 and 131 in a recording medium (not shown) at each input angle. The bias error correction unit 160 records the angle θ that makes the angular velocity closest to zero at the above input angle of 0° to 360° in a recording medium (not shown). This angle θ corresponds to the vibration azimuth θ0 that minimizes the zero-point bias output. Then, the bias error correction unit 160 sets the above angle θ as the command value for the angle input to the detection direction correction unit 105 and the drive direction correction unit 154 and outputs it as a command signal of the vibration azimuth θ0 to each direction correction unit. Thereby, the gyro sensor 1 is configured to perform a gyro operation in the vibration azimuth θ0 that minimizes the zero-point bias output.

[0181] According to the present embodiment, the gyro sensor 1 corrects the detection gain ratio G pxy and the drive gain ratio G fxy of the x-axis and y-axis of the vibrator 2 to reduce the error caused by the gain ratio of the x-axis and y-axis of the detection signal and the drive signal. In addition, after correcting the gain ratio of the detection signal and the drive signal, the gyro sensor 1 corrects the angular velocity to the value closest to zero in the detection direction and the drive direction, so that the zero-point bias output becomes minimum.

[0182] In addition, the gyro sensor 1 of the present embodiment minimizes the zero-point offset output in the measurement of the angular velocity by a control method including the following first to fourth steps. The first step is to calculate and determine the detection gain ratio G pxy , where the detection gain ratio G pxy is the ratio of the gain of the first detection signal from the first detection electrode that detects the vibration on the x-axis of the oscillator 2 to the gain of the second detection signal from the second detection electrode that detects the vibration on the y-axis. The second step is to calculate and determine the drive gain ratio G fxy , where the drive gain ratio G fxy is the ratio of the gain of the first drive signal for the first drive electrode for the first vibration mode to the gain of the second drive signal for the second drive electrode for the second vibration mode. In the third step, after determining the gain ratios G pxy and G fxy , the detection direction and drive direction of the vibration of the oscillator 2 are scanned by angular input in the range of 0° to 360°, and the angular velocity or drive output is calculated at each input angle. Then, in the third step, the value at which the angular velocity is closest to zero is determined as the command value (vibration azimuth θ0). The fourth step is to determine the detection direction and drive direction as the vibration azimuth θ0 and measure the angular velocity.

[0183] (1) In the gyro sensor 1, the detection gain ratio correction unit 106 multiplies the matrix of the formula (22) including the reciprocal of the detection gain ratio, i.e., 1 / G pxy , by the determinant of the formula (21) to cancel the matrix operation of the non-ideal detection gain ratio G pxy between the x-axis and the y-axis.

[0184] (2) In the gyro sensor 1, the drive gain ratio correction unit 153 multiplies the matrix of the formula (25) including the reciprocal of the drive gain ratio, i.e., 1 / G fxy , by the determinant of the formula (24) to cancel the matrix operation of the non-ideal drive gain ratio G fxy between the x-axis and the y-axis.

[0185] (Other Embodiments)

[0186] The present disclosure has been described based on the embodiments, but it should be understood that the present disclosure is not limited to the embodiments or structures. The present invention also includes various modifications and modifications within the equivalent range. Moreover, various combinations, manners, and other combinations, manners that include only one of them, include more elements or fewer elements also fall within the scope and spirit of the present disclosure.

[0187] In addition, regarding the sensor element, a structure in which the oscillator 2 has a substantially hemispherical shape or a substantially disk shape, and a plurality of first electrode portions 51 are arranged so as to surround the oscillator 2 has been described as a representative example, but it is not limited to these forms. For example, as long as the gyro sensor 1 is in a form in which the sensor element can be regarded as Figure 5 the vibrating body of the two-degree-of-freedom system shown, the above control can be performed by the control unit 10. Therefore, the forms, arrangements, etc. of the oscillator 2 and the electrode portions 51 and 52 can also be other known forms, arrangements, etc.

[0188] The control unit 10 and its method described in the present disclosure can also be implemented by a dedicated computer, which is provided by a processor and a memory configured to execute one or more functions embodied by a computer program. Alternatively, the control unit 10 and its method described in the present disclosure can also be implemented by a dedicated computer, which is provided by a processor constituted by one or more dedicated hardware logic circuits. Alternatively, the control unit 10 and its method described in the present disclosure can also be implemented by one or more dedicated computers, which are constituted by a combination of a processor programmed to execute one or more functions and a memory and a processor constituted by one or more hardware logic circuits. In addition, the computer program can also be stored as instructions executed by a computer in a computer-readable non-transitory tangible storage medium.

[0189] Furthermore, in each of the above embodiments, regarding the elements constituting the embodiments, unless specifically stated as essential or clearly considered essential in principle, etc., they are not necessarily essential. In addition, in the above embodiments, when referring to numerical values such as the number, value, quantity, range, etc. of the elements constituting the embodiments, unless specifically stated as essential or clearly limited to a specific number in principle, etc., they are not limited to that specific number. In addition, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the elements, etc., unless specifically stated or clearly limited to a specific shape, positional relationship, etc. in principle, etc., they are not limited to that shape, positional relationship, etc.

Claims

1. A gyro sensor, characterized in that: have: A vibrator having a first vibration mode and a second vibration mode having different resonant angular frequencies; A mounting substrate having a plurality of electrodes facing the vibrator; and a control unit that performs drive control of the vibrator, A radial direction is defined with an imaginary straight line passing through the center of the region surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate as an axis, and a direction along the vibration direction of the first vibration mode as the radial direction is set as an x-axis, and a direction along the vibration direction of the second vibration mode as the radial direction is set as a y-axis, The control unit has: a first PLL that performs frequency control of a first drive signal for driving the vibrator in the first vibration mode; a second PLL that performs frequency control of a second drive signal for driving the vibrator in the second vibration mode; The detection gain ratio correction unit performs detection gain ratio G pxy The correction of the detection gain ratio G pxy is a ratio of a gain of a first detection signal from a first detection electrode for detecting the vibration of the vibrator on the x-axis among the plurality of electrodes to a gain of a second detection signal from a second detection electrode for detecting the vibration of the vibrator on the y-axis among the plurality of electrodes; The drive gain ratio correction unit performs drive gain ratio correction. fxy The correction of the drive gain ratio G fxy is a ratio of a gain of the first drive signal to a first drive electrode among the plurality of electrodes for causing the vibrator to vibrate in the first vibration mode to a gain of the second drive signal to a second drive electrode among the plurality of electrodes for causing the vibrator to vibrate in the second vibration mode; a first demodulation block that performs operations on a first demodulation output based on the first detection signal and the first drive signal and a second demodulation output based on the first detection signal and the second drive signal; a second demodulation block that performs operations on a third demodulation output based on the second detection signal and the first drive signal and a fourth demodulation output based on the second detection signal and the second drive signal; a first AGC that performs a calculation of a drive output for maintaining the amplitude of the vibrator in the first vibration mode based on the output signal from the first demodulation block; a second AGC that performs operation of a drive output for maintaining the amplitude of the resonant vibration of the vibrator in the second vibration mode based on the output signal from the second demodulation block; an angular velocity calculation unit for calculating an angular velocity applied from the outside; as well as The offset error correction unit calculates an angle that makes the angular velocity calculated by the angular velocity calculation unit the value closest to zero after the detection gain ratio and the drive gain ratio are corrected, and determines the angle as the detection direction and the drive direction of the vibration of the vibrator.

2. The gyro sensor according to claim 1, characterized in that: The detection gain ratio correction unit performs a correction on 1 / G, which is the inverse of the detection gain ratio. pxy The matrix multiplication of the detection gain ratio is offset.

3. The gyro sensor according to claim 1 or 2, characterized in that: The drive gain ratio correction unit performs a correction operation to convert 1 / G, which is the inverse of the drive gain ratio, into fxy The matrix multiplication of the drive gain ratio is offset.

4. A method for controlling a gyro sensor, wherein a vibrator having a first vibration mode and a second vibration mode with different resonance angular frequencies is mounted on a mounting substrate having a plurality of electrodes facing the vibrator, wherein: include: Using two PLLs to maintain the driving of the vibrator in the first vibration mode and the second vibration mode; A radial direction with an imaginary straight line passing through the center of the region surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate as an axis is defined, the radial direction along the vibration direction of the first vibration mode is set as the x-axis, and the radial direction along the vibration direction of the second vibration mode is set as the y-axis, and the detection gain ratio G is calculated and determined. pxy , the detection gain ratio G pxy is a ratio of a gain of a first detection signal from a first detection electrode for detecting the vibration of the vibrator on the x-axis among the plurality of electrodes to a gain of a second detection signal from a second detection electrode for detecting the vibration of the vibrator on the y-axis among the plurality of electrodes; Calculate and determine the drive gain ratio G fxy , the driving gain ratio G fxy is a ratio of a gain of a first driving signal for a first driving electrode among the plurality of electrodes for causing the vibrator to vibrate on the x-axis to a gain of a second driving signal for a second driving electrode among the plurality of electrodes for causing the vibrator to vibrate on the y-axis; After the detection gain ratio and the drive gain ratio are determined, the detection direction and the drive direction of the vibration of the vibrator are scanned by inputting an angle in the range of 0° to 360°, and an angular velocity or a drive output for vibrating the vibrator is calculated at each input angle, and a value of the angular velocity closest to zero is determined as a command value; as well as The detection direction and the driving direction are determined as the angle of the command value, and the angular velocity is measured.

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