Gyro sensor and control method for gyro sensor

Abstract

To reduce the impact of gain on oscillator drive / detection signals and minimize 0-point bias output in a gyro sensor.SOLUTION: A sensor unit of the gyro sensor is composed of an oscillator 2 and a mounting board 3 having a plurality of electrodes facing the oscillator 2, and is controlled by a control unit 10 including a detection gain ratio correction unit 106, a drive gain ratio correction unit 153, and a bias error correction unit 160. With two oscillation axes of the oscillator 2 defined as an axis x and an axis y, the detection gain ratio correction unit 106 corrects the gain ratio of the detection signals of the x- and y-axis oscillations from the sensor unit, and the oscillation gain ratio correction unit 153 corrects the gain ratio of the x- and y-axis drive signals to the sensor unit. After correction of the detection and drive gain ratios, the bias error correction unit 160 calculates an angle at which an angular velocity calculated by an angular velocity calculation unit 132 becomes closest to zero, and determines the angle to be the detection / drive direction of oscillation of the oscillator 2.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a gyro sensor and a method for controlling the gyro sensor.

Background Art

[0002] Conventionally, there is known a gyro sensor having a vibrator having two vibration modes with different resonance angular frequencies and a plurality of electrodes surrounding the vibrator, applying an electrostatic force from a part of the electrodes to the vibrator to vibrate in a resonance mode, and detecting an angular velocity applied from the outside. This type of gyro sensor outputs a signal corresponding to the angular velocity applied from the outside based on the capacitance between the electrodes and the vibrator, but there is a signal output due to zero point error even when no angular velocity is applied. Hereinafter, for simplicity of explanation, the signal output from the gyro sensor in a state where no angular velocity is applied is referred to as "zero point bias output".

[0003] The main cause of the zero point bias output is a component derived from the asymmetry of the vibrator. Specifically, it is known to be caused by the difference Δ(1 / τ) in the Q values of the vibration axes x and y of the vibrator and θ τ . The zero point bias output is represented by the following equation (1).

[0004] Zero point bias output = (1 / 2η)Δ(1 / τ)sin2θ τ ···(1)

[0005] In equation (1), η is a constant determined by the structure of the vibrator called Angular gain, τ is a time constant, and θ τ is the angle between the damper axis of the vibrator and the electrode axis along the electrodes for driving and detecting the vibration of the vibrator.

[0006] Examples of gyro sensors capable of reducing the zero point bias output include those described in Non-Patent Document 1. The gyro sensor described in Non-Patent Document 1 is Δ(1 / τ)sin2θ which is a component of the zero point bias output τBy using a method called Mode Deflection that biases and deflects the mode onto the attenuation axis so that the bias becomes zero, the zero-point bias output is reduced.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, even when the gyro operation is performed in the direction where the bias output due to the above-mentioned mode deflection onto the attenuation axis, i.e., θ τ is the smallest, a residual may occur in the zero-point bias output. If there is a gain ratio between the two vibration axes of the vibrator in the drive signal and the vibration detection signal of the vibrator, 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 in which the drive command is given to the vibrator is different from the actual vibration direction of the vibrator, or when the actual vibration angle of the vibrator is different from the vibration angle read from the voltage value.

[0009] In addition, it is also conceivable to perform numerical correction so that the zero - point bias output represented by the formula (1) becomes zero on the system by calibration or the like. However, since the zero - point bias output may vary due to the influence of temperature changes or changes over time in the operating state, in such cases, the effect of reducing the zero - point bias output by calibration or the like will be diminished. Also, even with this method, similar to the method described in Non - Patent Document 1, it cannot handle the case where there is a gain ratio between the two vibration axes in the detection signal or the drive signal.

[0010] In view of the above points, an object of the present disclosure is to provide a gyro sensor and its control method capable of reducing the influence of the gain ratio between the two vibration axes of the drive / detection signals of the vibrator and minimizing the zero - point bias output.

Means for Solving the Problems

[0011] According to one aspect of the present disclosure, a gyro sensor includes a vibrator (2) having a first vibration mode and a second vibration mode with different resonance angular frequencies, a mounting substrate (3) having a plurality of electrodes (51) facing the vibrator, and a control unit (10) that executes drive control of the vibrator. Taking a virtual 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, in the radial direction, the direction along the vibration direction of the first vibration mode is defined as the x - axis, and the direction along the vibration direction of the second vibration mode is defined as the y - axis. The control unit a first PLL (140) that executes frequency control of a first drive signal for resonantly driving the vibrator in the first vibration mode, a second PLL (141) that executes frequency control of a second drive signal for resonantly driving the vibrator in the second vibration mode, a detection gain ratio (G) which is the ratio between the gain of a first detection signal from a first detection electrode that detects vibration of the vibrator on the x - axis among the plurality of electrodes and the gain of a second detection signal from a second detection electrode that detects vibration of the vibrator on the y - axis among the plurality of electrodes pxyA detection gain ratio correction unit (106) that corrects A drive gain ratio (G), which is the ratio of the gain of the first drive signal to the first drive electrode for vibrating the vibrator in the first vibration mode among the plurality of electrodes, and the gain of the second drive signal to the second drive electrode for vibrating the vibrator in the second vibration mode among the plurality of electrodes. fxy A drive gain ratio correction unit (153) that corrects A first demodulation block (110) that performs calculations on a first demodulation output (V Xi1 , V Xq1 ) based on the first detection signal and the first drive signal, and a second demodulation output (V Xi2 , V Xq2 ) based on the first detection signal and the second drive signal. A third demodulation output (V Yi1 , V Yq1 ) based on the second detection signal and the first drive signal, and a fourth demodulation output (V Yi2 , V Yq2 ) based on the second detection signal and the second drive signal. A first AGC (130) that performs calculations on the drive output for maintaining the amplitude in the resonance drive in the first vibration mode of the vibrator based on the output signal from the first demodulation block. A second AGC (131) that performs calculations on the drive output for maintaining the amplitude in the resonance vibration in the second vibration mode of the vibrator based on the output signal from the second demodulation block. An angular velocity calculation unit (132) that executes calculations on the angular velocity applied from the outside. After correcting the detection gain ratio and the drive gain ratio, a bias error correction unit (160) that calculates the angle at which the angular velocity calculated by the angular velocity calculation unit is closest to zero, and determines the detection direction and the drive direction of the vibration of the vibrator as the angle.

[0012] In this gyro sensor, the gain ratios of the detection signals and drive signals of the vibrator on the x-axis and y-axis are corrected by a detection gain ratio correction unit and a drive gain ratio correction unit, respectively, and the influence of the gain ratio on the x-axis and y-axis of the drive / detection signal of the vibrator is reduced. Further, in this gyro sensor, after the correction of the detection gain ratio and the drive gain ratio, for the detection direction and the drive direction, since the angular velocity is corrected to the value closest to zero, the zero-point bias output is minimized.

[0013] 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 a vibrator (2) having a first vibration mode and a second vibration mode with different resonance angular frequencies is mounted on a mounting substrate (3) having a plurality of electrodes (51) facing the vibrator, using two PLLs (140, 141) to maintain resonance driving of the vibrator in the first vibration mode and the second vibration mode, a detection gain ratio (G pxy ) which is the ratio of the gain of the first detection signal from the first detection electrode that detects the vibration of the vibrator on the x-axis among the plurality of electrodes to the gain of the second detection signal from the second detection electrode that detects the vibration of the vibrator on the y-axis among the plurality of electrodes, is calculated and determined, a drive gain ratio (G fxy ) which is the ratio of the gain of the first drive signal to the first drive electrode for vibrating the vibrator on the x-axis among the plurality of electrodes to the gain of the second drive signal to the second drive electrode for vibrating the vibrator on the y-axis among the plurality of electrodes, is calculated and determined, after determining the detection gain ratio and the drive gain ratio, while the detection direction and the drive direction of the vibration of the vibrator are angle-input and swept in the range of 0° to 360°, the angular velocity or the drive output for vibrating the vibrator is calculated for each input angle, and the value closest to zero of the angular velocity is determined as the command value (θ0), Determining the detection direction and the driving direction as the angle of the command value and measuring the angular velocity.

[0014] This method for controlling a gyro sensor determines, by calculation, a detection gain ratio that is the gain ratio of the detection signals of the x-axis and y-axis of the vibrator, and calculates and determines a driving gain ratio that is the gain ratio of the driving signals of the x-axis and y-axis. Thereby, the error due to the gain ratio between the x-axis and y-axis of the detection signal and the driving signal is reduced. Then, after correcting the detection gain ratio and the driving gain ratio, the control method sweeps the input angle in the range of 0° to 360° for the detection direction and the driving direction, determines the value closest to zero of the angular velocity as the command value, and performs angular velocity measurement with the command value. Thereby, it becomes a control method for a gyro sensor capable of reducing the influence of the gain ratio on the x-axis and y-axis of the driving / detection signal of the vibrator and minimizing the zero-point bias output.

[0015] Note that the reference numerals in parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

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Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each of the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

[0018] (First Embodiment) The gyro sensor 1 of the first embodiment will be described with reference to the drawings.

[0019] 〔Basic Configuration〕 The gyro sensor 1 of the present embodiment has, for example, as shown in FIG. 1, a vibrator 2 and a mounting substrate 3, and includes a sensor element in which the vibrator 2 is mounted on the mounting substrate 3. The gyro sensor 1 can detect the angular velocity and the rotated angle applied to the gyro sensor 1 based on the change in capacitance between a part of the thin vibrator 2 that can vibrate in the first vibration mode and the second vibration mode and a plurality of first electrode portions 51 of the mounting substrate 3. The gyro sensor 1 can be controlled by a control unit 10 described later to minimize the zero-point bias output.

[0020] The vibrator 2 is, for example, as shown in FIG. 2, a three-dimensional substantially symmetric micro-vibrator including a curved surface portion 21 including an outer shape of a substantially hemispherical three-dimensional curved surface, and a mounting portion 22 extending from the apex side of the virtual hemisphere formed by the curved surface portion 21 toward the center side of the hemisphere. The vibrator 2 has, for example, conductive films (not shown) formed on both the front and back surfaces, and voltage can be applied from the mounting substrate 3. And, for example, at the end of the curved surface portion 21 opposite to the mounting portion 22, a rim 23 faces a plurality of first electrode portions 51, and the rim 23 vibrates in a resonance mode by the electrostatic force from the first electrode portions 51.

[0021] Note that the vibrator 2 can be manufactured, for example, by preparing a plate material made of an arbitrary reflow material such as quartz and a mold having a bowl-shaped recess and a support portion located at the center of the recess, setting the plate material in the mold, and heating and softening it while reducing the pressure in the recess.

[0022] Also, the vibrator 2 may have a substantially disc shape, for example, as shown in FIG. 3, having a disc-shaped portion and a columnar connection portion joined to the mounting substrate 3 at the center of the portion. In this case, at the end of the disc-shaped portion in the hollow state, the rim 23 is present, and the portion is surrounded by a plurality of first electrode portions 51. Thus, the vibrator 2 may have a structure capable of vibrating in a first vibration mode and a second vibration mode by a driving electrode among the plurality of first electrode portions 51, and in addition to the above structure, other known structures may also be used.

[0023] As shown in FIGS. 1 and 2 for example, the mounting substrate 3 includes a lower substrate 4 and an upper substrate 5, which are joined together. For example, the mounting substrate 3 is obtained by performing wiring film formation or the like on a lower substrate 4 made of borosilicate glass as an insulating material, and then anodically joining an upper substrate 5 made of silicon as a semiconductor material to the lower substrate 4 and performing patterning. The mounting substrate 3 has, for example, a plurality of first electrode portions 51 and second electrode portions 52 formed by performing dry etching such as DRIE (Deep Reactive Ion Etching) on the upper substrate 5 after anodic bonding. Also, for example, when the vibrator 2 has the bird bath shape shown in FIG. 2, an annular groove (not shown) along the rim 23 may be formed in the lower substrate 4 as necessary so as not to contact the rim 23.

[0024] The plurality of first electrode portions 51 are arranged at equal intervals and separated from each other so as to draw one ring on the plane of the mounting substrate while surrounding the rim 23 of the vibrator 2, and electrode films (not shown) are formed on their respective upper surfaces. The plurality of first electrode portions 51 are, for example, connected to a wire (not shown) in the electrode film (not shown) and electrically connected to an external circuit board or the like, so that the potential thereof can be controlled. All of the plurality of first electrode portions 51 are in a state of being separated from the rim 23 of the vibrator 2 by a predetermined distance, and each forms a capacitor with the vibrator 2, enabling detection of the capacitance between the vibrator 2 and the first electrode portions. A part of the plurality of first electrode portions 51 serves as a detection electrode for detecting capacitance, and another part serves as a drive electrode for applying an electrostatic force to the rim 23 of the vibrator 2.

[0025] As shown in FIG. 1 for example, the second electrode portion 52 has a frame shape surrounding the plurality of first electrode portions 51, an electrode film (not shown) is formed on the upper surface, and a wire (not shown) is connected to the electrode film (not shown). The second electrode portion 52 is connected to a conductive film (not shown) of the vibrator 2 by wiring or the like (not shown) and is configured to be able to apply a voltage.

[0026] The above is the basic configuration of the sensor element in the gyro sensor 1 of this embodiment. The control unit 10 that executes the drive control of the gyro sensor 1 will be described later.

[0027] In FIG. 1, the case where the mounting substrate 3 has 16 first electrode portions 51 and one frame-shaped second electrode portion 52 is shown as a representative example, but it is not limited thereto. For the first electrode portion 51 and the second electrode portion 52, for example, the number, arrangement, shape, etc. may be appropriately changed.

[0028] 〔Vibration Model and Zero-Point Bias Output〕 Next, the vibration model and zero-point bias output of the vibrator 2 will be described.

[0029] When the vibrator 2 is viewed from the normal direction to the plane formed by the mounting substrate 3 (hereinafter referred to as "top view"), by applying a voltage to a part of the first electrode portion 51, for example, as shown in FIG. 4, a resonance state is achieved in which the number of bellies and nodes in the vibration amplitude of the outer contour of the rim 23 is 2n each. n is an integer of 2 or more, and such a resonance state of the vibrator 2 is called the "wineglass mode". In FIG. 4, a representative example of the resonance mode of n = 2 in the wineglass mode, in which the vibration axes x and y to be described later coincide with the electrode axes X and Y, is shown, but the vibrator 2 can also be vibrated in higher-order wineglass modes of n = 3 or more.

[0030] Hereinafter, for convenience of explanation, as shown in FIG. 4, with the center position of the rim 23 in the top view 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 the straight line as the axis is called the "substrate circumferential direction". Also, among the directions along the substrate radial direction, the direction passing through the belly position of the vibration of the rim 23 of the vibrator 2 in the first vibration mode (resonance angular frequency ω1) 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 wineglass 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 wineglass mode of n = 2, the angle formed by the vibration axis x and the vibration axis y is 45°.

[0031] The plurality of first electrode portions 51 are arranged apart from each other along, for example, the circumferential direction of the substrate, and are arranged so that the distances from the rim 23 in the non-vibrating state are substantially the same. Here, for the sake of convenience of explanation, for example, as shown in FIG. 4, one direction on the actual plane where the plurality of first electrode portions 51 are arranged is defined as the "X r direction", and the direction orthogonal to the X r direction on the same plane is defined as the "Y r direction", and the same plane is defined as the "X r Y r plane". Then, one direction in the X r Y r plane is defined as the "electrode axis X", and the direction in which the electrode axis X points when rotated counterclockwise by (360 / 4k)° along the circumferential direction of the substrate on the X r Y r plane is defined as the "electrode axis Y".

[0032] The vibrator 2 can be regarded as a vibrating body of a two-degree-of-freedom system that vibrates in a two-dimensional plane, with, for example, as shown in FIG. 5 in a top view, two springs with spring constants k x and k y connected to two objects with damping coefficients C x and C y along its vibration direction. FIG. 5 shows the conversion of the vibration axes x, y and the electrode axes X, Y in the X r Y r plane into a rectangular coordinate system, with the origin of the vibration axes x, y and the origin of the electrode axes X, Y made to coincide. Hereinafter, the vibration axes x, y may be simply referred to as the x-axis and the y-axis.

[0033] Note that the two-dimensional plane mentioned here means the plane along the surface of the mounting substrate 3 on which the plurality of first electrode portions 51 are formed. The spring constants k x and k y are the spring constants on the vibration axes x and y, respectively, and the damping coefficients C x and C y are the damping coefficients of the vibration on the vibration axes x and y, respectively. The angle θ ωis the angle formed by the electrode axes X and Y and the vibration axes x and y which are the spring axes, and is the angle θ τ is the angle formed by the electrode axes X and Y and the damper axis along the direction in which vibration decays. The sensor element composed of the vibrator 2 and the mounting substrate 3 usually has θ ω ≠0 unless special processing or the like is performed.

[0034] Here, the equation of motion of the two-degree-of-freedom vibration model shown in FIG. 5 is represented by the following equation (2).

[0035]

Equation

[0036] In equation (2), ω is the resonance angular frequency of the vibrator 2, and Δω is the absolute value of the difference between these when the resonance angular frequencies of the first vibration mode and the second vibration mode are ω1 and ω2. The zero-point bias output is expressed as in equation (1) as described above, but this is obtained from equation (2). The zero-point bias output depends on the Q-value difference Δ(1 / τ) of the vibration axes x and y and θ τ Note that Δ(1 / τ) and τ are expressed by the following equations (3) and (4).

[0037] Δ(1 / τ)=(1 / τ x )-(1 / τ y ) ··· (3) τ = 1 / (ζω)=2Q / ω n =Q / πf ··· (4)

[0038] In equation (3), τ x , τ y are the time constants on the x-axis and y-axis. In equation (4), ζ is the damping ratio, and ω n is the natural angular frequency.

[0039] The zero-point bias output has a sine-wave-like waveform as shown in, for example, FIG. 6 when the vibration orientation of the vibrator 2 is taken as the horizontal axis and the vertical axis is the zero-point bias output from equation (1). That is, θ τTaking the vibration orientation θ0 at which the zero - point bias output becomes zero, the zero - point bias output is minimized by adjusting θ τ so that it becomes θ0. The gyro sensor 1 corrects the gain ratios of the x - and y - axes of the detection signal from the sensor unit composed of the vibrator 2 and the mounting substrate 3 and the gain ratios of the x - and y - axes of the drive signal to the sensor unit, and then controls the vibration orientation as described above to minimize the zero - point bias output. Details of this will be described later. Note that the sensor unit means a part composed of a sensor element composed of the vibrator 2 and the mounting substrate 3 and a circuit (not shown) such as a current - voltage conversion circuit used for voltage application to a plurality of first electrode portions 51.

[0040] 〔Control Unit〕 Next, the control unit 10 of the gyro sensor 1 will be described.

[0041] The control unit 10 includes, for example, as shown in FIG. 7, detection circuits 101 and 102 for detecting the vibrations of the x - axis and y - axis of the vibrator 2, and ADCs 103 and 104 for converting 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 a signal from a detection electrode that detects the vibration of the x - axis among a plurality of first electrode portions 51. The detection circuit 102 detects a signal from a detection electrode that detects the vibration of the y - axis of the vibration axis among a 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.

[0042] The control unit 10 includes, for example, a detection - direction correction unit 105 into which signals from the ADCs 103 and 104 are input, a detection - gain - ratio correction unit 106, a first demodulation block 110, and a second demodulation block 120.

[0043] The detection direction correction unit 105 corrects the detection directions of the vibrations in the x-axis and y-axis, for example, based on the input signal from the bias error correction unit 160 described later. After the correction of the detection gain ratio and the drive gain ratio, the detection direction correction unit 105 executes a process of correcting the detection direction of the vibration to the vibration azimuth θ0 at which the zero-point bias output is minimized.

[0044] The detection gain ratio correction unit 106 corrects the gain ratio of the detection signals between the x-axis and the y-axis, that is, the detection gain ratio, for example, based on the information from the demodulation blocks 110 and 120 when the AGCs 130, 131, and PLLs 140, 141 described later are operated. The detection gain ratio calculated by the detection gain ratio correction unit 106 or the demodulation output calculation unit 113 is used for calculating the vibration azimuth at which the zero-point bias output is minimized. The calculation of the detection gain ratio will be described later.

[0045] The first demodulation block 110 calculates a demodulation output related to the vibration axis x, for example, based on the input signal from the detection gain ratio correction unit 106. Further, the first demodulation block 110 outputs, for example, an amplitude component in phase with the frequency signal and an amplitude component having a 90° phase shift from the frequency signal, based on the frequency signal for 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.

[0046] The first demodulation unit 111 calculates, for example, demodulation outputs V Xβ and V Xi1 based on the first drive signal for resonantly driving the vibrator 2 in the first vibration mode at the resonance angular frequency ω1 and the processing signal V Xq1 . The demodulation outputs V Xi1 and V Xq1 are calculated based on the detection signals from the detection electrodes on the x-axis, and are the demodulation output in phase (In Phase) with the drive signal at the resonance angular frequency ω1 of the first vibration mode and the demodulation output in quadrature phase with the drive signal, respectively. The second demodulation unit 112 calculates, for example, demodulation outputs based on the second drive signal for resonantly driving the vibrator 2 in the second vibration mode at the resonance angular frequency ω2 and the processing signal V XβBased on this, the demodulated output V Xi2 , V Xq2 is calculated. This is possible because in a system where the resonance driving of the resonance angular frequencies ω1 and ω2 of the oscillator 2 is 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. The demodulated outputs V Xi2 , V Xq2 are respectively calculated based on the detection signals from the detection electrodes on the x-axis, and are the demodulated output in phase with the drive signal of the resonance angular frequency ω2 of the second vibration mode and the demodulated output with a quadrature phase with respect to the drive signal. The demodulated output calculation unit 113 calculates, for example, the amplitude and phase of the first vibration mode of the oscillator 2 based on V Xi1 , V Xq1 , V Xi2 , V Xq2 .

[0047] The second demodulation block 120 calculates, for example, the demodulated output related to the vibration axis y based on the input signal from the detection gain ratio correction unit 106. Further, the second demodulation block 120 outputs, for example, the amplitude component in phase with the frequency signal and the amplitude component with a 90° phase shift from the frequency signal with respect to the vibration axis y based on the frequency signal from the PLL 141 described later. The second demodulation block 120 includes, for example, a first demodulation unit 121, a second demodulation unit 122, and a demodulated output calculation unit 123.

[0048] The first demodulation unit 121 calculates, for example, the demodulated outputs V Yβ , V Yi2 based on the second drive signal described above and the processing signal V Yq2 . The demodulated outputs V Yi2 , V Yq2 are, for example, the demodulated output in phase with the frequency signal of the resonance angular frequency ω2 of the second vibration mode and the demodulated output with a quadrature phase with respect to the drive signal, respectively, calculated based on the detection signals from the detection electrodes on the y-axis. The second demodulation unit 122 calculates, for example, the demodulated output V Yβ based on the first drive signal described above and the processing signal V Yi1, V Yq1 is calculated. Similar to the above, the demodulation by the second demodulation unit 122 is possible because the processing signal V Yβ contains information about the vibration amplitude in the x-direction of the vibration axis of the first vibration mode. The demodulation output V Yi1 , V Yq1 are, for example, calculated based on the detection signals from the detection electrodes on the y-axis respectively, and are the demodulation outputs in phase with the frequency signal of the resonance angular frequency ω1 of the first vibration mode and the demodulation output in quadrature with the drive signal. The demodulation output calculation unit 113 calculates, for example, the amplitude and phase of the second vibration mode of the vibrator 2 based on V Yi1 , V Yq1 , V Yi2 , V Yq2 . The calculation of each of the above demodulation outputs will be described later.

[0049] The control unit 10 includes an AGC 130 and a PLL 140 for resonantly driving the vibrator 2 in the first vibration mode and maintaining it, and an AGC 131 and a PLL 141 for resonantly driving the vibrator 2 in the second vibration mode and maintaining it. AGC is an abbreviation for Automatic Gain Control and is also referred to as automatic gain control. PLL is an abbreviation for Phase Locked Loop and is also referred to as a phase-locked loop.

[0050] For example, the AGC 130 receives amplitude information about the x-direction of the vibration axis of the first vibration mode of the vibrator 2 from the first demodulation block 110, and performs calculations and signal outputs for controlling the amplitude in the first vibration mode to a predetermined constant value based on the amplitude information. The AGC 130 outputs, for example, a control signal for amplitude fixation to the modulation unit 151 and outputs a signal for angular velocity calculation to the angular velocity calculation unit 132.

[0051] The AGC 131 receives, for example, amplitude information in the y-axis direction of the second vibration mode of the vibrator 2 from the second demodulation block 120, and performs calculations and signal output for controlling the amplitude in the second vibration mode to a predetermined constant value based on the amplitude information. The AGC 131 outputs, for example, a control signal for amplitude fixation to the modulation unit 152 and outputs a signal for angular velocity calculation to the angular velocity calculation unit 132.

[0052] The angular velocity calculation unit 132, for example, subtracts the input signals V Ω+ , V Ω- from the AGCs 130 and 131, and divides the resulting value by a scale factor measured in advance to calculate the angular velocity externally applied to the gyro sensor 1. Also, the angular velocity calculation unit 132 calculates, for example, the angular velocity for each angular input of the bias error correction unit 160 described later when determining the vibration orientation for minimizing the zero-point bias output.

[0053] The PLL 140 receives, for example, phase information about the first vibration mode of the vibrator 2 from the first demodulation block 110, and performs frequency control and signal output of a first drive signal for resonantly driving the vibrator 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 signal of the demodulation output V Xq1 , and based on the corrected signal, the NCO circuit outputs a first drive signal of a predetermined frequency. 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.

[0054] The PLL 141 receives, for example, phase information regarding the second oscillation mode of the oscillator 2 from the second demodulation block 120, and performs frequency control and signal output of a second drive signal for resonantly driving the oscillator 2 at the resonance angular frequency ω2. The PLL 141 has, for example, the same configuration as the PLL 140, and a PI circuit corrects the demodulated output V Yq2 signal, and an NCO circuit outputs a second drive signal having a predetermined frequency based on the corrected signal. The PLL 141 outputs signals to the demodulation blocks 110, 120, and the modulation unit 152.

[0055] The control unit 10 includes, for example, a modulation unit 151 to which output signals from the AGC 130 and the PLL 140 are input, and a modulation unit 152 to which output signals from the AGC 131 and the PLL 141 are input.

[0056] The modulation unit 151 superimposes, for example, the frequency signal from the PLL 140 on 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 superimposes, for example, the frequency signal from the PLL 141 on the amplitude control signal input from the AGC 131, and outputs the superimposed signal to the drive gain ratio correction unit 153.

[0057] The control unit 10 includes, for example, a drive gain ratio correction unit 153, a drive direction correction unit 154, DACs 155 and 156, and drive circuits 157 and 158.

[0058] The drive gain ratio correction unit 153 calculates a gain ratio of the drive signals for the x-axis and the y-axis, that is, a drive gain ratio, based on the input signals from the modulation units 151 and 152 when the AGCs 130 and 131 and the PLLs 140 and 141 are operated. The drive gain ratio calculated by the drive gain ratio correction unit 153 is used, together with the detection gain ratio, for calculating the oscillation orientation at which the zero-point bias output is minimized. The calculation of the drive gain ratio will be described later.

[0059] The driving direction correction unit 154 corrects the vibration directions of the x-axis and y-axis based on, for example, the input signal from the bias error correction unit 160. The driving direction correction unit 154 executes a process of correcting the driving direction to the vibration azimuth θ0 calculated after the correction of the detection gain ratio and the driving gain ratio.

[0060] The DACs 155 and 156 convert, for example, the digital signals for driving control of the vibrator 2 input from the driving direction correction unit 154 into analog signals and output them to the driving circuits 157 and 158 respectively. DAC is the abbreviation of Digital to Analog Converter.

[0061] The driving circuits 157 and 158 output driving signals for the x-axis and y-axis to the driving electrodes among the plurality of first electrode portions 51 respectively in order to vibrate the vibrator 2 in the resonance mode. As a result, a force F due to electrostatic force acts on the vibrator 2 for the x-axis x and a force F due to electrostatic force acts on the vibrator 2 for the y-axis y respectively, and vibration control is performed.

[0062] The bias error correction unit 160 calculates, for example, the vibration azimuth θ0 at which the zero-point bias output becomes minimum after the correction of the detection gain ratio and the driving gain ratio, and outputs a command signal corresponding to the calculated vibration azimuth θ0 to the detection direction correction unit 105 and the driving direction correction unit 154. The calculation of the vibration azimuth θ0 by the bias error correction unit 160 will be described later.

[0063] The above is the basic configuration of the control unit 10. Note that the control unit 10 is not limited to the example shown in FIG. 7, and it is sufficient that the control can minimize the zero-point bias output, and the configuration may be changed as appropriate.

[0064] For example, the control unit 10 may be configured such that 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. For example, the control unit 10 may be configured such that 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. The control unit 10 may be configured to perform, for example, the gyro operation in an open-loop operation that does not feedback the y-direction information input to the second demodulation block 120. In this case, for example, the control unit 10 is configured such that the signals from the demodulation blocks 110 and 120 are directly input to the angular velocity calculation unit 132. Further, the control unit 10 may be configured to execute FtR control that feedbacks the y-direction information input to the second demodulation block 120 to control the y-direction amplitude to 0 and calculates the angular velocity from the control voltage at this time. Note that FtR is an abbreviation for Force to Rebalance. Thus, the control unit 10 can be appropriately changed for some of its components.

[0065] 〔Calculation in Demodulation Block〕

[0066] Next, the calculation of the demodulation output in the demodulation blocks 110 and 120 will be described.

[0067] When the vibrator 2 resonantly drives both the first vibration mode and the second vibration mode in the resonance mode with n = 2, for example, as shown in FIG. 8, it vibrates along two orthogonal vibration axes x and y. Let the vibration amplitude and the resonance angular frequency on the vibration axis x be A and ω1, respectively, the vibration amplitude and the resonance angular frequency on the vibration axis y be B and ω2, respectively, and 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).

[0068] x = A sin(ω1t + φ1) ··· (5) y = B sin(ω2t + φ2) ··· (6)

[0069] φ1 in equation (5) and φ2 in equation (6) are the phases with respect to the external forces applied from each direction. The respective components of the vibration with amplitude A on the electrode axes X and Y are a X , a Y , and the respective components of the vibration with amplitude B on the electrode axes X and Y are b X , b Y . Then, θ ω , which is the deviation angle between the vibration axis x and the electrode axis X, is expressed by the following equation (7) due to the orthogonality of the vibration axes x and y.

[0070]

Equation

[0071]

Equation

[0072] X = a X sin(ω1t + φ1) + b X sin(ω2t + φ2) ··· (9) Y = a Y sin(ω1t + φ1) + b Y sin(ω2t + φ2) ··· (10) Note that each component a X , b X , a Y , b Y in equations (9) and (10) are, in the example shown in FIG. 8, a X = Acosθ ω , b X = -Bsinθ ω , a Y = Asinθ ω , b Y = Bcosθ ω . Also, the conversion coefficients from the amplitude to the voltage according to the detection method are ξ X , ξY Assuming that, the voltages V XP and V YP at the detection electrodes of the electrode axes X and Y respectively are represented by the following equations (11) and (12).

[0073] V XP = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)} ··· (11) V YP = ξ Y {a Y sin(ω1t + φ1) + b Y sin(ω2t + φ2)} ··· (12) The first demodulation unit 111 performs an operation of the demodulation outputs V XP and V Xi1 with respect to the external forces on the vibration axes x and y based on the voltage V Xq1 in the equation (11). The demodulation output V Xi1 is calculated by multiplying the voltage V XP by sinω1t and passing it through a low-pass filter to eliminate the second harmonic and the frequency sum terms as represented by the following equation (14).

[0074]

Equation

[0075]

Equation

[0076] |f(t)| in the equation (14) LPF means the operation of eliminating the second harmonic and the frequency sum terms passed through the above-mentioned low-pass filter. The same applies to the following equations (16), (18), and (20).

[0077] The demodulation output V Xq1 is represented by the following equation (15) as the voltage V XPIt is calculated by multiplying by cosω1t and performing an operation to eliminate unnecessary terms through a low-pass filter as represented by Equation (16).

[0078]

Number

[0079]

Number

[0080] V XP sin(ω2t + Δφ)=ξ X {a X sin(ω1t + φ1)+b X sin(ω2t + φ2)}sin(ω2t + Δφ) ··· (17)

[0081]

Number

[0082] V XP cos(ω2t + Δφ) = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)}cos(ω2t + Δφ) ··· (19)

[0083]

Number

[0084] The demodulation outputs V Xi1 , V Xq1 , V Xi2 , V Xq2 , V Yi1 , V Yq1 , V Yi2 , V Yq2 are output to, for example, the demodulation output arithmetic units 113, 123, etc., and are used for calculating the amplitudes and phase differences of the first and second vibration modes. Hereinafter, for the sake of simplicity of explanation, the demodulation outputs V Xi1 , V Xq1 , V Xi2 , V Xq2 , V Yi1 , VYq1 and V Yi2 and V Yq2 are collectively referred to as "each demodulation output".

[0085] For example, the demodulation output calculation units 113 and 123 are configured to include a high-pass filter (hereinafter referred to as "HPF"), a calculation unit that performs calculations using each demodulation output after passing through the HPF, and a phase comparison unit that calculates the phase difference of the respective demodulation outputs.

[0086] The demodulation output calculation unit 113, for example, calculates |ξ Xi1 and V Xq1 by performing a sum-of-squares calculation that adds the squares of each of them calculated by the calculation unit. The demodulation output calculation unit 113 calculates |ξ X b X |. The demodulation output calculation unit 113 calculates |ξ Xi2 and V Xq2 by performing a sum-of-squares calculation in the calculation unit based on them. The demodulation output calculation unit 113 calculates |ξ X a X |. Also, the demodulation output calculation unit 113 calculates the phase difference Δφ Xi1 and V Xi2 based on and calculates the phase difference Δφ Xi respectively based on the demodulation output V Xq1 and V Xq2 after passing through the HPF. Xq

[0087] The demodulation output calculation unit 123 calculates |ξ Yi1 and V Yq1 by performing a sum-of-squares calculation based on them in the same manner as the demodulation output calculation unit 113. The demodulation output calculation unit 123 calculates |ξ Y b Y |. The demodulation output calculation unit 123 calculates |ξ Yi2 and V Yq2 by performing a sum-of-squares calculation based on them. The demodulation output calculation unit 123 calculates |ξ Y a Y |. Also, the demodulation output calculation unit 123 calculates the phase difference Δφ Yi1 and V Yi2 based on and calculates the phase difference Δφ Yi using V Yq1 and V Yq2 ​Based on the phase difference Δφ Yq perform calculations respectively.

[0088] The demodulation blocks 110 and 120 are, for example, |ξ X a X |, |ξ Y a Y |, |ξ X b X |, |ξ Y b Y |, and the amplitude information of the resonance mode can be obtained respectively by the above calculations of |ξ Xi , Δφ Xq , Δφ Yi , Δφ Yq and the phase information of the resonance mode can be obtained respectively by the above calculations of Δφ. Hereinafter, for simplicity of explanation, the calculations of |ξ X a X |, |ξ Y a Y |, |ξ X b X |, |ξ Y b Y | for calculating the above amplitudes are simply referred to as "amplitude calculations".

[0089] 〔Detection Gain Ratio, Driving Gain Ratio, and Reduction of Zero - Point Bias Output〕 Next, the detection gain ratio and the driving gain ratio will be described.

[0090] In a system for inputting a driving force to the oscillator 2 as shown in FIG. 7, consider the case where the ratio of non - ideal gains of the x - axis and the y - axis exists as G pxy . Hereinafter, this non - ideal gain ratio is referred to as the detection gain ratio G pxy . In this case, for the x and y of the vibration information of the oscillator 2, the voltages input to each axis are V x , V y , and the voltages V x , V y and the detection gain ratio G pxy are represented by the following equation (21).

[0091]

Equation

[0092] The non-ideal detection gain ratio G in the formula (21) pxy To cancel it, the detection gain ratio G may be calculated by some means pxy and multiplied by the determinant of the following formula (22) in the formula (21).

[0093]

Equation

[0094] In each gain ratio operation mode, the control unit 10 inputs the detection signals of the vibrations in the x and y axes from the sensor unit through the detection circuits 101 and 102 and the ADCs 103 and 104 to the demodulation blocks 110 and 120, and performs amplitude calculation based on each demodulation output and each demodulation output. Also, 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, held in a recording medium (not shown) in the control unit 10 and then read from the recording medium and used in the angular velocity calculation mode for calculating the angular velocity. This also applies to the drive gain ratio G fxy described later.

[0095] 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).

[0096] [Number]

[0097] D in formula (23) x and D y are calculated values obtained by operations shown in FIGS. 11 and 12, for example. Specifically, for example, as shown in FIG. 11, the first demodulation block 110 performs amplitude operations based on the demodulated output V Xi1 and amplitude operations based on the demodulated output V Xq1 to calculate a first addition value obtained by adding two values obtained by each amplitude operation. Further, for example, the first demodulation block 110 performs amplitude operations based on the demodulated output V Xi2 and amplitude operations based on the demodulated output V Xq2 to calculate a second addition value obtained by adding two values obtained by each amplitude operation. Then, for example, the first demodulation block 110 multiplies the first addition value and the second addition value to calculate the calculated value D x .

[0098] The second demodulation block 120 performs amplitude operations based on the demodulated outputs V Yi1 and V Yq1 respectively as shown in FIG. 12, for example, adds the two obtained values to calculate a third addition value. Further, for example, the second demodulation block 120 performs amplitude operations based on the demodulated outputs V Yi2 and V Yq2 respectively, calculates a fourth addition value obtained by adding two values obtained by each amplitude operation, and then multiplies the third and fourth addition values to calculate the calculated value D y .

[0099] Then, as shown in FIG. 13, for example, the detection gain ratio correction unit 106 performs an operation of taking the square root of the value obtained by dividing the calculated value D x by the calculated value D y to calculate the detection gain ratio G pxy . Then, the detection gain ratio correction unit 106 calculates the detection gain ratio G pxyBased on the above, a detection gain ratio correction value represented by equation (22) is calculated, and the detection gain ratio is corrected by multiplying this value by equation (21).

[0100] Next, in the system where driving forces F x , F y are input, consider the case where the ratio of the non-ideal gains of driving forces F x and F y exists as G fxy . Hereinafter, the non-ideal gain ratio in these two driving forces F x , F y is referred to as the driving gain ratio G fxy . Let the output signal from DAC155 on the x-axis and the output signal from DAC156 on the y-axis be VF x、 VF y respectively. Based on the driving signals from driving circuits 157 and 158, the driving forces F x , F y applied to the vibrator 2 are expressed by the following equation (24) including the driving gain ratio G fxy .

[0101]

Equation

[0102] In order to cancel the non-ideal driving gain ratio G fxy in equation (24), the driving gain ratio G fxy is calculated by some means, and the determinant of the following equation (25) may be multiplied by equation (24).

[0103]

Equation

[0104]

Number

[0105] Finally, after the correction of the detection gain ratio and the drive gain ratio, the control unit 10 drives the vibrator 2 in the resonance mode in a stationary state where no angular velocity is applied to the gyro sensor 1 to perform a gyro operation. The bias error correction unit 160 inputs an angle in the range of 0° to 360° to the detection direction correction unit 105 and the drive direction correction unit 154 to rotate the gyro operation axis by 360°. At this time, the bias error correction unit 160, for example, sweeps the input angle at an arbitrary angle step and an arbitrary drive time, and records the angular velocity or the drive outputs of the AGCs 130 and 131 for each input angle on a recording medium (not shown). The bias error correction unit 160 records the angle θ at which the angular velocity becomes the value closest to zero at the input angles of 0° to 360° described above on 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 a command value for the angle input to the detection direction correction unit 105 and the drive direction correction unit 154, and outputs it to each direction correction unit as a command signal for the vibration azimuth θ0. Thereby, the gyro sensor 1 is configured to perform a gyro operation in the vibration azimuth θ0 where the zero-point bias output is minimized.

[0106] According to the present embodiment, in the gyro sensor 1, the detection gain ratios G pxy and the drive gain ratios G fxy of the x-axis and y-axis of the vibrator 2 are corrected, and the error due to the gain ratio between the x-axis and y-axis of the detection signal and the drive signal is reduced. Further, after the correction of the gain ratios of the detection signal and the drive signal, the gyro sensor 1 corrects the detection direction and the drive direction to the value closest to zero for the angular velocity, so that the zero-point bias output is minimized.

[0107] Also, the gyro sensor 1 of the present embodiment minimizes the zero-point bias output in the measurement of the angular velocity by a control method including the following first to fourth steps. The first step is the detection gain ratio G which 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 vibrator 2 to the gain of the second detection signal from the second detection electrode that detects the vibration on the y-axis. pxyis to calculate and determine. The second step is the drive gain ratio G, which is the ratio of the gain of the first drive signal to the first drive electrode used for the first vibration mode and the gain of the second drive signal to the second drive electrode used for the second vibration mode fxy is to calculate and determine. In the third step, the gain ratio G pxy , G fxy After determining, while sweeping the detection direction and drive direction of the vibration of the vibrator 2 by inputting an angle in the range of 0° to 360°, the angular velocity or drive output is calculated for each input angle. Then, in the third step, the value closest to zero of the angular velocity is determined as the command value (vibration orientation θ0). The fourth step is to determine the detection direction and drive direction to the vibration orientation θ0 and measure the angular velocity

[0108] (1) The gyro sensor 1 multiplies the matrix of equation (22) including 1 / G, which is the reciprocal of the detection gain ratio, by the determinant of equation (21), and performs a matrix operation to cancel the non-ideal detection gain ratios G pxy between the x-axis and the y-axis pxy

[0109] (2) The gyro sensor 1 multiplies the matrix of equation (25) including 1 / G, which is the reciprocal of the drive gain ratio, by the determinant of equation (24), and performs a matrix operation to cancel the non-ideal drive gain ratios G fxy between the x-axis and the y-axis fxy

[0110] (Other embodiments) Although the present disclosure has been described based on examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one element thereof, more, or less, fall within the scope and spirit of the present disclosure

[0111] ​​In addition, as a representative example, the sensor element has been described with a configuration in which the vibrator 2 has a substantially hemispherical shape or a substantially disc shape, and a plurality of first electrode portions 51 are arranged so as to surround the vibrator 2. However, the present invention is not limited to such forms. For example, if the gyro sensor 1 is in a form in which the sensor element can be regarded as a two-degree-of-freedom vibrator shown in FIG. 5, the above-described control by the control unit 10 is possible. Therefore, the forms and arrangements of the vibrator 2 and the electrode portions 51 and 52 may be other known ones.

[0112] The control unit 10 and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit 10 and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the control unit 10 and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor programmed to execute one or more functions and a memory and a processor configured by one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

[0113] It goes without saying that in each of the above embodiments, the elements constituting the embodiment are not necessarily essential, except in cases where it is explicitly stated that they are particularly essential and cases where they are considered to be clearly essential in principle. Also, in each of the above embodiments, when numerical values such as the number, numerical value, amount, and range of the components of the embodiment are mentioned, they are not limited to the specific number, except in cases where it is explicitly stated that they are particularly essential and cases where they are clearly limited to a specific number in principle. Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the components, etc., they are not limited to the shape, positional relationship, etc., except in cases where it is explicitly stated and cases where they are clearly limited to a specific shape, positional relationship, etc. in principle.

Description of Symbols

[0114] 2... Vibrator, 3... Mounting substrate, 10... Control unit, 51... First electrode part, 106... Detection gain ratio correction part, 110... First demodulation block, 120... Second demodulation block, 130, 131... AGC, 132... Angular velocity calculation part, 140, 141... PLL, 153... Driving gain ratio correction part, 160... Bias error correction part, G fxy ... Driving gain ratio, G pxy ... Detection gain ratio, V Xi1 、V Xq1 、V Xi2 、V Xq2 、V Yi1 、V Yq1 、V Yi2 、V Yq2 … Demodulation output

Claims

1. A gyro sensor, comprising: a vibrator (2) having a first vibration mode and a second vibration mode with different resonance angular frequencies; a mounting substrate (3) having a plurality of electrodes (51) facing the vibrator; a control unit (10) for executing drive control of the vibrator. Taking a virtual 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, in the radial direction, with the direction along the vibration direction of the first vibration mode as the x-axis and the direction along the vibration direction of the second vibration mode as the y-axis, the control unit a first PLL (140) for executing frequency control of a first drive signal for resonantly driving the vibrator in the first vibration mode; a second PLL (141) for executing frequency control of a second drive signal for resonantly driving the vibrator in the second vibration mode; The detection gain ratio (G), which is the ratio of the gain of the first detection signal from the first detection electrode that detects the vibration of the vibrator in the x-axis among the plurality of electrodes, to the gain of the second detection signal from the second detection electrode that detects the vibration of the vibrator in the y-axis among the plurality of electrodes ｐｘｙ A detection gain ratio correction unit (106) that corrects The drive gain ratio (G), which is the ratio of the gain of the first drive signal to the first drive electrode for causing the vibrator to vibrate in the first vibration mode among the plurality of electrodes, and the gain of the second drive signal to the second drive electrode for causing the vibrator to vibrate in the second vibration mode among the plurality of electrodes ｆｘｙ A drive gain ratio correction unit (153) that corrects the drive gain ratio A first demodulation output (V Ｘｉ１ , V Ｘｑ１ ) based on the first detection signal and the first drive signal, and a second demodulation output (V Ｘｉ２ , V Ｘｑ２ ) based on the first detection signal and the second drive signal, and a first demodulation block (110) that performs an operation of A third demodulation output (V Ｙｉ１ , V Ｙｑ１ ) based on the second detection signal and the first drive signal, and a fourth demodulation output (V Ｙｉ２ , V Ｙｑ２ ) based on the second detection signal and the second drive signal, and a second demodulation block (120) that performs an operation of a first AGC (130) for performing an operation of drive output to maintain the amplitude in the resonant drive of the vibrator in the first vibration mode based on the output signal from the first demodulation block; a second AGC (131) for performing an operation of drive output to maintain the amplitude in 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 (132) for calculating the angular velocity applied from the outside; a bias error correction unit (160) for calculating an angle at which the angular velocity calculated by the angular velocity calculation unit becomes the value closest to zero after correction of the detection gain ratio and the drive gain ratio, and determining the angle as the detection direction and the drive direction of the vibration of the vibrator.

2. The detection gain ratio correction unit multiplies a matrix including 1 / G which is the reciprocal of the detection gain ratio, and performs matrix operation to cancel the detection gain ratio. The gyro sensor according to claim 1 ｐｘｙ which performs matrix operation to cancel the detection gain ratio by multiplying a matrix including 1 / G which is the reciprocal of the detection gain ratio. The gyro sensor according to claim 1

3. The drive gain ratio correction unit multiplies a matrix including 1 / G, which is the reciprocal of the drive gain ratio, and performs a matrix operation that cancels out the drive gain ratio. The gyro sensor according to claim 1 or 2. ｆｘｙ ​

4. A control method for a gyro sensor in which a vibrator (2) having a first vibration mode and a second vibration mode with different resonance angular frequencies is mounted on a mounting substrate (3) having a plurality of electrodes (51) facing the vibrator, comprising: using two PLLs (140, 141) to maintain resonant driving of the vibrator in the first vibration mode and the second vibration mode; Taking as the x-axis the direction along the vibration direction of the first vibration mode, which is the radial direction with respect to the virtual straight line passing through the center of the region surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate, and taking as the y-axis the direction along the vibration direction of the second vibration mode, calculating the detection gain ratio (G ｐｘｙ ), which is the ratio of the gain of the first detection signal from the first detection electrode that detects the vibration of the vibrator in the x-axis among the plurality of electrodes to the gain of the second detection signal from the second detection electrode that detects the vibration of the vibrator in the y-axis among the plurality of electrodes, and determining it; The drive gain ratio (G), which is the ratio of the gain of the first drive signal to the first drive electrode for vibrating the vibrator along the x-axis among the plurality of electrodes, and the gain of the second drive signal to the second drive electrode for vibrating the vibrator along the y-axis among the plurality of electrodes ｆｘｙ ), is calculated and determined; After determining the detection gain ratio and the drive gain ratio, while sweeping by inputting angles in the range of 0° to 360° for the detection direction and the drive direction of the vibration of the vibrator, calculate the angular velocity or the drive output for vibrating the vibrator for each input angle, and determine the value closest to zero of the angular velocity as the command value (θ ０ ), and determining the detection direction and the drive direction as the angle of the command value and measuring the angular velocity.

Images