JP2006194701A - Oscillation gyro - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillation gyro which generates an angular velocity signal ωa which represents a precisely compensated bias fluctuating, according to the temperature change of a vibrator and has a structure that is high in reliability and simple in structure. <P>SOLUTION: A detection signal 101b represents the angular velocity ω the vibrator 1 receives. The resonance frequency of the vibrator 1 is a function of the temperature of the vibrator 1. A self-excited oscillation section 2 undergoes self-excited oscillation at the resonance frequency of the vibrator 1. A signal 102 by the self-excited oscillation turns into a waveform-shaped signal 103 with its frequency information being retained, and the frequency of the signal 103 is measured by a frequency measurement section 81. The output 181 of the frequency measurement section 81, which is frequency data, is outputted as the temperature signal 181, since it corresponds to the temperature of the vibrator 1. A bias compensation amount calculating section 82, on the basis of the temperature data represented by the temperature signal 181, generates a bias compensation amount signal 108. An analog adder 9 adds the bias compensation amount signal 108 to an angular velocity signal 107, to generate the angular velocity signal ωa with the bias compensated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vibrating gyroscope having a vibrator that vibrates at a mechanical resonance frequency, and a detection circuit that detects a vibration generated in the vibrator by a Coriolis force according to an angular velocity of the vibrator as a detection vibration. The present invention relates to a compensation amount calculation unit of a vibration gyro capable of correcting variations in bias and scale factor due to the above.

  The basic principle of the vibration gyro is described in Non-Patent Document 1, for example. As this type of vibratory gyro, vibrators having various shapes such as tuning fork vibrators such as U-shaped, quadruped, and hexapods and horns are used. As the material of the vibrator forming the vibrator, a constant elastic material such as Elinba, or a piezoelectric single crystal such as silicon or quartz, lithium tantalate, lithium niobate, or langasite is used. When the vibrating body is a constant elastic material or silicon, a piezoelectric element made of piezoelectric ceramic is attached to the vibrating body, and an electrode is deposited on the piezoelectric element. When the vibrating body is made of a piezoelectric single crystal, an electrode is deposited. The electrodes include a drive electrode for applying a drive signal and a detection electrode for extracting detection vibration.

  An example of a vibration gyro of a hexapod vibrator is described in Patent Document 1 or Patent Document 2. FIG. 8 is a diagram for explaining the basic structure and operation of the tuning fork type vibration gyro described in Patent Document 1 or Patent Document 2. However, the hexapodal vibrator has three driving legs and three detection legs arranged at equal intervals on both ends of a rectangular plate-shaped body part. Since this is for stabilizing the vibration and is not important in the explanation of the operation principle, FIG. 8 shows a quadruped vibrator in which the central leg is omitted. The vibrator shown in FIG. 8 includes a body portion 10, a driving leg (driving side arm in Patent Document 1) 111, and a detecting leg (detecting side arm in Patent Document 1) 112. The drive leg 111 includes excitation drive legs 111a and 111b. The detection leg 112 includes vibration detection legs 112a and 112b.

  FIG. 8A shows the state of the vibrator when there is no rotation input to the tuning fork type vibration gyro, and FIG. 8B shows the state of the vibrator when there is a rotation input to the tuning fork type vibration gyro. . The excitation drive legs 111a and 111b are paired with each other and vibrate in opposite phases. The vibration detection legs 112a and 112b are paired with each other and vibrate in opposite phases. The trunk | drum 10 is a rectangular parallelepiped, The planar shape (shape of the upper surface 10a) is a square (it does not necessarily need to be a square). Each surface of the body 10 has a top surface represented by reference numeral 10a, a bottom surface (not shown in the figure) represented by reference numeral 10b, an end surface on the drive leg 111 side represented by reference numeral 10c, and an end surface on the detection leg 112 side (in the figure). (Not appearing) is represented by reference numeral 10d, one side surface is represented by reference numeral 10e, and the other side surface (not appearing in the figure) is represented by reference numeral 10f. The upper surface 10a and the bottom surface 10b are called main surfaces.

  The body 10, the excitation drive legs 111 a and 111 b, and the vibration detection legs 112 a and 112 b are made of one piezoelectric single crystal, and are cut out from a single plate-like piezoelectric single crystal. The body 10, the excitation drive legs 111 a and 111 b and the vibration detection legs 112 a and 112 b have the same thickness. In a state where the excitation drive legs 111a and 111b are not excited, that is, in a stationary state, the axes of the excitation drive legs 111a and 111b and the axes of the vibration detection legs 112a and 112b are respectively on the end surfaces 10c and 10d of the body part 10. It is vertical. The axes of the excitation drive leg 111a and the vibration detection leg 112a are on the same axis. Similarly, the axes of the excitation drive leg 111b and the vibration detection leg 112b are on the same axis. In addition, the excitation drive legs 111a and 111b are symmetrical and the vibration detection legs 112a and 112b are also symmetrical with respect to a plane that passes through the center of gravity of the body portion 10 and is parallel to the side surface 10e. Excitation drive legs 111a and 111b and vibration detection legs 112a and 112b are provided with drive electrodes and detection electrodes, respectively (the illustration of these electrodes is omitted).

  When an AC voltage for excitation is applied to the drive electrode in the tuning fork type vibration gyro having the structure shown in FIG. 8, the excitation drive legs 111a and 111b are opposite to each other in the plane parallel to the upper surface 10a, that is, reverse. Vibrates in phase. This vibration is drive vibration in the tuning fork type vibration gyro. The drive vibration is vibration in a plane parallel to the main surface (the upper surface 10a and the bottom surface 10b) of the trunk portion 10, and such vibration in a plane parallel to the main surface is referred to as in-plane vibration. In-plane vibration is indicated by arrows Ha and Hb in FIG. In this state, when the rotation of the angular velocity ω is input around the input shaft in FIG. 8B, a Coriolis force is generated in proportion to the leg end velocity due to the leg vibration. It becomes the vibration of the same frequency. This vibration is referred to as Coriolis vibration in the sense of vibration based on Coriolis force. When the leg vibrates so that the displacement of the leg end is in the range of ± a, the absolute value of the leg end velocity is zero when the displacement of the leg end is ± a, and the displacement of the leg end is zero. It becomes the maximum at the time of. In the tuning fork type vibration gyro having the structure shown in FIG. 8, when the rotation of the angular velocity ω is inputted around the input shaft shown in FIG. 8B, Coriolis force acts on the excitation drive legs 111a and 111b, and the Coriolis vibrations Ca and Cb. Each occurs. The Coriolis vibrations Ca and Cb are vibrations in a direction perpendicular to the main surface of the body portion 10, and their phases are opposite to each other. The vibration in the direction perpendicular to the main surface of the body portion 10 is referred to as surface vertical vibration.

  Since the body portion 10 is plate-shaped, it has extremely high rigidity against vibration in a direction parallel to the main surface, that is, in-plane vibration, and vibration in a direction orthogonal to the main surface, that is, surface vertical vibration. Shows relatively low rigidity. Therefore, among the vibrations generated in the excitation drive legs 111a and 111b, the drive vibrations Ha and Hb that are in-plane vibrations hardly propagate to the vibration detection legs 112a and 112b, and the other surface vertical vibrations are Coriolis vibrations. Ca and Cb propagate to the vibration detection legs 112a and 112b with high efficiency. The Coriolis vibrations propagated to the vibration detection legs 112a and 112b are detected vibrations Da and Db in the tuning fork type vibration gyro. The tuning fork type vibration gyro detects the angular velocity ω by taking out the voltage appearing on the vibration detection legs 112a and 112b as an electric signal with the detection electrodes by the detection vibrations Da and Db.

  In the tuning fork type vibration gyro, the drive vibration component appearing on the vibration detection legs 112a and 112b is noise, and the detected vibration component (Da, Db) is a signal. Therefore, since the ratio of the drive vibration component to the detected vibration component (Da, Db) in the vibration detection legs 112a, 112b becomes a signal-to-noise ratio (S / N ratio), in order to detect the angular velocity ω with high accuracy, It is necessary to reduce the drive vibration component that leaks and appears in the vibration detection legs 112a and 112b. The drive vibration component leaking to the vibration detection legs 112a and 112b becomes a bias for the signal component [detected vibration component (Da, Db)]. If this bias is unstable, the detection accuracy of the angular velocity ω is lowered. The bias is a signal resulting from vibration appearing on the detection leg even when the angular velocity ω is not input to the vibration gyro. The causes of the bias include a shape error of the vibrator, an electrode formation error, and partial restriction of the vibrator due to the vibrator support structure.

  FIG. 7 is a functional block diagram of the vibrating gyroscope. As a tuning fork type vibrator in the vibrating gyroscope, a quadruped vibrator is shown in FIG. 8, but in the vibrating gyroscope of FIG. 7, the vibrator is U-shaped for simplification of illustration. In the vibrating gyroscope, a detection signal representing the angular velocity ω input to the vibrator is acquired from the vibrator by supplying a driving signal for exciting the vibrator to the vibrator. If the number of legs of the vibrator changes, the number and phase of the drive signal and detection signal change, but the basic configuration of the vibrating gyroscope does not change regardless of the number of legs of the vibrator. Therefore, the vibration gyro provided with the quadruped vibrator of FIG. 8 can also be realized by the circuit of the functional block diagram similar to FIG. In FIG. 7, the vibrator 1 is formed by vapor-depositing a drive electrode and a detection electrode on a vibrating body made of a piezoelectric single crystal.

  7 includes a vibrator 1, a self-excited transmission unit 2, a waveform shaping unit 3, a phase unit 4, an AC amplification unit 5, a synchronous detection unit 6, and a DC amplification unit 7. The self-excited transmission unit 2 is a transmission circuit that uses the vibrator 1 as a resonance means, and generates a drive signal 102. The vibrator 1 is excited by the drive signal 102 and returns an electric signal appearing on the electrode to the self-excited transmission unit 2 as a feedback signal 101a, and a detection signal 101b appearing on the detection electrode when an angular velocity ω is input from the outside. Is output to the AC amplifier 5. The waveform shaping unit 3 is composed of a comparator or the like, shapes the waveform of the drive signal 102, and outputs a waveform shaping drive signal 103. The phase unit 4 moves the phase of the waveform shaping drive signal 103 and generates a reference signal 104. The AC amplifying unit 5 amplifies the detection signal 101b that is an AC signal, and outputs an amplified detection signal 105. The synchronous detection unit 6 performs synchronous detection of the amplified detection signal 105 with the reference signal 104 and outputs a detection signal 106. The direct current amplifier 7 amplifies the detection signal 106 which is a direct current signal, and outputs the direct current amplified detection signal as an angular velocity signal ωa.

  The vibrator 1 of the vibration gyro outputs a detection signal 101b representing the angular velocity ω, but the detection signal 101b is weak and is an AC signal whose phase is 90 ° different from that of the drive signal 102. Therefore, in the vibration gyro, in order to obtain the angular velocity signal ωa, the detection signal 101b is first amplified by the AC amplification unit 5 to output the AC signal 105, and the AC signal 105 is synchronously detected by the synchronous detection unit 6. 105 is converted into a DC detection signal 106 and then further amplified by the DC amplifier 7. Further, in order to generate the reference signal 104 used in the synchronous detection unit 6, the waveform of the drive signal 102 is shaped by the waveform shaping unit 3, and the phase adjustment is performed by the phase shift unit 4.

"Ultrasonic electronics vibration theory-application and basics", Yoshiro Miyagawa, Asakura Shoten JP 2001-255152 A JP 2001-208545 A JP 05-288555 A

  In the vibration gyro, as described above with reference to FIG. 8, the actual angular velocity ω input to the vibration gyro is zero due to the shape error of the vibrator 1, the electrode formation error, the influence of the vibrator mounting structure, and the like. In some cases, the output angular velocity signal ωa may not be zero, and the angular velocity signal ωa output when the input angular velocity ω is zero is referred to as a bias. If the vibrator 1 has temperature fluctuation, the elastic coefficient, dimensions, mechanical strain, etc. of the vibrator 1 will fluctuate. Therefore, the bias varies depending on the temperature of the vibrator 1.

  Further, when a temperature change is applied to the vibration gyroscope, the phase relationship between the input signal 105 and the reference signal 104 of the synchronous detection unit 6 changes due to the piezoelectric characteristic change of the vibrator 1 or the electric characteristic change of the electric circuit. . This variation in phase appears as a change in sensitivity in angular velocity measurement. When the sensitivity fluctuates, the angular velocity signal ωa, which is the output signal of the vibration gyroscope, fluctuates, again resulting in a measurement error of the angular velocity signal ωa. The measurement error due to this sensitivity change can be said to be a change in scale factor in a measuring instrument called a vibration gyroscope.

  FIG. 5 is a functional block diagram of a vibrating gyroscope having a compensation amount calculation unit disclosed in Patent Document 3. In FIG. 5, 15 is a temperature sensor installed in the vicinity of the vibrator 1, 18 is a compensation amount calculation unit, and 9 is an analog adder. The compensation amount calculation unit 18 is formed by connecting an A / D converter, a PLD (programmable logic device), and a D / A converter in cascade. Elements indicated by reference numerals 1 to 7 in FIG. 5 operate in the same manner as in FIG. In the circuit of FIG. 5, the output 107 (the angular velocity signal before bias compensation) of the DC amplification unit 7 is connected to one input terminal of the analog adder 9. The compensation amount calculation unit 18 generates a digitized temperature signal by performing A / D conversion on the temperature signal 115 output from the temperature sensor 15 by an A / D converter, and processes the digitized temperature signal by the PLD. Thus, the bias compensation amount signal is generated, the D / A conversion is performed on the bias compensation amount signal by the D / A converter, and the analog bias compensation amount signal 118 is input to the other input terminal of the analog adder 9. ing. Thus, the vibration gyro of FIG. 5 obtains an angular velocity signal ωa whose bias is compensated as an output of the analog adder 9 by adding the elements of 15, 18 and 9 to the elements of FIG. The bias varies according to the temperature variation of the vibrator 1, but since the bias compensation amount signal 118 is corrected based on the temperature signal 115, the bias is compensated by the bias compensation amount signal 118 regardless of the environmental temperature. . In Patent Document 3, the output 107 of the DC amplification unit 7 is an angular velocity signal including a bias, but the angular velocity signal ωa is assumed to represent an angular velocity ω excluding the bias component. Although the bias varies according to the temperature variation of the vibrator 1, the bias compensation amount signal 118 is corrected based on the temperature signal 115. Therefore, the bias compensation signal 118 compensates the bias regardless of the environmental temperature. However, it can be seen from Patent Document 3 for the time being.

  However, in the vibration gyro of Patent Document 3 shown in FIG. 5, even if the temperature sensor 15 is installed in the vicinity of the vibrator 1, the temperature sensor 15 does not measure the temperature of the vibrator 1 itself. A correction error is inevitable in the bias compensation amount signal 118. In addition, since the installation of the temperature sensor 15 in the vicinity of the vibrator 1 entails an increase in man-hours and parts costs, the method of Patent Document 3 uses a vibration gyro for providing a function of bias compensation according to the environmental temperature. Increasing manufacturing costs is inevitable. In addition, the method of Patent Document 3 in which the temperature sensor is installed has a drawback that the reliability of the vibration gyro is impaired due to the complicated support structure of the temperature sensor and fragile wiring.

  Further, when a temperature change is applied to the vibration gyroscope, the phase relationship between the input signal 105 and the reference signal 104 in the synchronous detector 6 varies due to the piezoelectric characteristic variation of the vibrator 1 or the electrical circuit characteristic variation. To do. This phase variation appears as a change in sensitivity with respect to the angular velocity signal ωa, but the sensitivity cannot be corrected by the method of Patent Document 3.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration gyro including a compensation amount calculation unit that is reliable with a simple structure and is capable of at least one of proper bias compensation and sensitivity correction.

  In order to solve the above-mentioned problems, the present invention provides the following means.

(1) Using the vibrator, one resonance frequency of the vibrator as a drive signal, vibrator driving means for driving the vibrator, and Coriolis vibration appearing in the vibrator according to the angular velocity received by the vibrator A bias compensation amount generating means for generating a bias compensation amount for compensating a bias which is an output value of the Coriolis vibration detecting means when the vibrator is not receiving the angular velocity, and a Coriolis vibration detecting means In a vibration gyro having a bias removing unit that generates an angular velocity signal that does not include the bias by combining the output and the bias compensation amount, and removing the bias from the output of the Coriolis vibration detecting unit.
The bias compensation amount generating means generates the bias compensation amount according to the resonance frequency.

(2) The bias compensation amount generating means measures the resonance frequency and outputs a value corresponding to the measured frequency as temperature data of the vibrator, and calculates the bias compensation amount based on the temperature data. A bias compensation amount calculation unit to generate,
The bias compensation amount calculation unit stores in advance a polynomial or a lookup table having a temperature as a variable, and obtains the bias compensation amount corresponding to the temperature data by the polynomial or the lookup table. The vibrating gyroscope according to (1).

(3) A vibrator, a vibrator driving means for driving the vibrator, and a Coriolis vibration appearing in the vibrator according to an angular velocity received by the vibrator, using a resonance frequency of the vibrator as a drive signal And means for
The Coriolis vibration detection means includes a phase shift unit that generates a reference signal by transferring the phase of the drive signal, and a synchronous detection unit that synchronously detects Coriolis vibration of the output of the vibrator using the reference signal. In vibration gyro,
A phase correction amount signal is generated based on a change in the resonance frequency, and the phase correction amount signal is supplied to the phase shift unit.
The phase amount correction means represents, as the phase correction amount signal, a phase having a magnitude sufficient to correct a variation amount of the phase difference between the Coriolis vibration and the reference signal caused by temperature fluctuation of the vibrator.
The phase shift unit shifts the phase of the reference signal by a phase correction amount represented by the phase correction amount signal.

(4) a bias compensation amount generating means for generating a bias compensation amount for compensating a bias that is an output value of the Coriolis vibration detecting means when the vibrator does not receive the angular velocity; A bias removing unit that generates an angular velocity signal that does not include the bias by combining the output and the bias compensation amount, and removing the bias from the output of the Coriolis vibration detecting unit;
The vibration gyro according to (3), wherein the bias compensation amount generation unit acquires temperature data of the vibrator based on the resonance frequency, and generates the bias compensation amount according to the temperature data. .

  According to the present invention, since the temperature of the vibrator 1 is measured by utilizing the fact that the resonance frequency of the vibrator 1 varies according to the temperature of the vibrator 1 itself, a bias compensation error associated with the temperature measurement position occurs. Absent. Further, according to the present invention, it is possible to provide a vibration gyro having a compensation amount calculation unit that corrects not only bias compensation but also fluctuations in sensitivity due to environmental temperature. Furthermore, according to the present invention, since a temperature sensor is not required, it is possible to provide a highly reliable vibration gyro which can be downsized with a simple structure and can be manufactured at low cost.

  Next, embodiments of the present invention will be described, and the present invention will be described more specifically with reference to the drawings. FIG. 1 is a functional block diagram showing a vibration gyro according to a first embodiment of the present invention. The compensation amount calculation unit 8 in this embodiment obtains temperature data from the waveform shaping drive signal 103 output from the waveform shaping unit 3. On the other hand, the compensation amount calculator 18 in the conventional vibration gyro shown in FIG. 5 obtains temperature data from the temperature signal 115 output from the temperature sensor 15. Therefore, the compensation amount calculation unit 8 in the embodiment of FIG. 1 is different from the compensation amount calculation unit 18 of FIG. 5 in configuration and operation. In the embodiment of FIG. 1, the temperature sensor 15 of FIG. 5 is not required. In other respects, the embodiment of FIG. 1 is the same as the conventional vibrating gyroscope of FIG. 5, and therefore, the embodiment of FIG. 1 will be described below focusing on these differences.

  The compensation amount calculation unit 8 of the embodiment of FIG. 1 calculates a compensation amount (a value obtained by inverting the polarity of the estimated bias amount) based on the temperature data, similarly to the conventional vibration gyro shown in FIG. The bias compensation amount signal 108 is generated, and the bias compensation amount signal 108 is directly added to the output signal 107 (the angular velocity signal before bias compensation) of the DC amplifier 7 to cancel the bias.

  FIG. 3 is a functional block diagram of the first embodiment (FIG. 1) showing a specific configuration example of the compensation amount calculation unit 8. The compensation amount calculation unit 8 in FIG. 3 includes a frequency measurement unit 81 and a bias compensation amount calculation unit 82. The frequency measuring unit 81 receives the waveform shaping drive signal 103 output from the waveform shaping unit 3 and measures the frequency of the waveform shaping drive signal 103. Since the frequency of the waveform shaping drive signal 103 is the same as the frequency of the drive signal 102, the count value of the frequency measuring unit 81 represents the frequency of the drive signal 102. Since the frequency of the drive signal 102 is the oscillation frequency of the self-excited transmission unit 2, it is the resonance frequency of the vibrator 1.

  FIG. 6 is a graph showing the relationship between the resonance frequency of the vibrator 1 and the temperature. As described above, the resonance frequency of the vibrator 1 varies with the temperature coefficient of the thermal expansion coefficient and the elastic modulus of the vibrator 1 and is a function of the temperature of the vibrator 1. Therefore, in the compensation amount calculation unit 8 in the embodiment of FIG. 3, the frequency data of the vibrator 1 can be obtained by measuring the frequency of the waveform shaping drive signal 103 by the frequency measurement unit 81. The output signal 181 of the frequency measuring unit 81 is a signal representing the resonance frequency of the vibrator 1 and is also a temperature signal because this resonance frequency uniquely corresponds to the temperature of the vibrator 1. In this embodiment, the signal 181 is referred to as a temperature signal.

  The compensation amount calculation unit 8 in the embodiment of FIG. 3 measures the frequency of the waveform shaping drive signal 103 with the frequency measurement unit 81 instead of the temperature signal 115 of the temperature sensor 15 output in the conventional vibration gyro of FIG. Thus, the temperature data of the vibrator 1 is obtained, and the bias compensation amount calculation unit 82 calculates the bias compensation amount according to the temperature data to generate the bias compensation amount signal 108.

  The bias compensation amount calculation unit 82 has a polynomial or a look-up table with temperature as a variable, and generates an output corresponding to one-to-one with respect to the input. In order to determine the coefficient in the polynomial or the table value of the lookup table, the bias is measured in advance by the temperature test of the vibration gyro. The temperature test is performed by measuring the bias at regular temperature intervals over the entire temperature range of the environment in which the vibration gyro is used. A value obtained by inverting the polarity of the bias at each temperature obtained from this test is the bias compensation amount at each temperature. When calculating the compensation amount using a polynomial, each coefficient in the polynomial is calculated and stored in the bias compensation amount calculation unit 82 so that the value of the polynomial at each temperature becomes the compensation amount at each temperature. When calculating the compensation amount using the lookup table, the compensation amount for each temperature is stored in the bias compensation amount calculation unit 82 as a table value for each temperature.

  In the first embodiment of the present invention described with reference to FIGS. 1 and 3, the self-excited oscillation unit 2 corresponds to the above-described vibrator driving means, and includes a waveform shaping unit 3, a phase shift unit 4, and an AC amplification unit. 5 and the synchronous detection unit 6 correspond to the above-mentioned Coriolis vibration detection means, the compensation amount calculation unit 8 corresponds to the above-mentioned bias compensation amount generation means, and the DC amplification unit and the analog adder 9 correspond to the above-described bias removal means. To do.

  FIG. 2 is a functional block diagram showing a vibration gyro according to a second embodiment of the present invention. When a temperature change is applied to the vibration gyro, the phase relationship between the amplification detection signal 105 and the reference signal 104 that is an input signal of the synchronous detection unit 6 is changed due to the piezoelectric characteristic fluctuation of the vibrator 1 or the electric characteristic fluctuation in the electric circuit. fluctuate. Since this phase fluctuation appears as a fluctuation in the magnitude of the angular velocity signal ωa, it becomes a change in the sensitivity of the vibration gyro. When the sensitivity fluctuates, the angular velocity signal ωa, which is the output signal of the vibration gyroscope, fluctuates, again resulting in a measurement error of the angular velocity signal ωa. The measurement error due to this sensitivity change can be said to be a change in scale factor in a measuring instrument called a vibration gyroscope. In the embodiment of FIG. 1, the measurement error due to the sensitivity change cannot be corrected.

  In the embodiment of FIG. 2, in order to correct the phase variation, the phase of the magnitude of the variation is calculated as a correction phase amount by the compensation amount calculation unit 80, and the phase correction amount signal 108b representing the correction phase amount is obtained. Is added to the phase shifter 4 and the phase of the reference signal 104 is shifted by the amount of the corrected phase, thereby preventing phase fluctuation between the two input signals (the amplified detection signal 105 and the reference signal 104) of the synchronous detector 6. is doing. In this way, by adjusting the phase of the reference signal 104 by the phase shift unit 4 by the phase amount corresponding to the phase correction amount signal 108b, the sensitivity variation due to the temperature variation is compensated, and the scale factor of the vibration gyro Correction is possible. The compensation amount calculation unit 80 also has a function of generating the bias compensation amount 108 and compensating for the bias in the angular velocity signal 107, similarly to the compensation amount calculation unit 8 in the embodiment of FIG.

  FIG. 4 is a functional block diagram of the second embodiment showing a specific configuration example of the compensation amount calculation unit 80. The compensation amount calculation unit 80 includes a frequency measurement unit 81, a bias compensation amount calculation unit 82, and a sensitivity correction calculation unit 83. The frequency measurement unit 81 and the bias compensation amount calculation unit 82 in the compensation amount calculation unit 80 in FIG. 4 are the same as those in the compensation amount calculation unit 8 in FIG. Since the compensation amount for the bias and the correction amount for the sensitivity are different, the compensation amount calculation unit 80 includes a sensitivity correction calculation unit 83 separately from the bias compensation amount calculation unit 82. Similar to the bias compensation amount calculation unit 82 in the embodiment of FIG. 3, the sensitivity correction calculation unit 83 has a polynomial or look-up table with temperature as a variable, and outputs an output corresponding to one-to-one with respect to the input. Generate. In order to determine the coefficient value of the polynomial or the table value of the lookup table, a temperature test of the vibration gyroscope is performed, and the amount of phase fluctuation between the amplified detection signal 105 and the reference signal 104 due to temperature fluctuation is measured in advance. . A polynomial coefficient or a table value of a lookup table is determined so that a value obtained by inverting the polarity of the phase variation amount is generated as a correction phase amount. The coefficient or table value in the sensitivity correction calculation unit 83 is determined in the same manner as the coefficient value or table value in the bias compensation amount calculation unit 82 described above. The sensitivity correction calculation unit 83 applies the temperature signal 181 to a polynomial or lookup table stored in advance, calculates a correction phase amount, and generates a phase correction amount signal 108b representing the correction phase amount.

  In the second embodiment of the present invention described with reference to FIGS. 2 and 4, the self-excited oscillation unit 2 corresponds to the above-described vibrator driving unit, and includes a waveform shaping unit 3, a phase shift unit 4, and an AC amplification unit. 5 and the synchronous detection unit 6 correspond to the above-mentioned Coriolis vibration detection means, the compensation amount calculation unit 80 corresponds to the bias compensation amount generation means, the DC amplification unit and the analog adder 9 correspond to the above-described bias removal means, The sensitivity correction calculation unit corresponds to the aforementioned phase amount correction means.

  Although the embodiments of the present invention have been specifically described above with reference to the drawings, it goes without saying that the present invention is not limited to these embodiments. For example, the input signal of the compensation amount calculation units 8 and 80 (corresponding to the bias compensation amount generation means) in the above embodiment is the drive signal 103 with the waveform shaping, but it is replaced with the drive signal 103 with the waveform shaping. The drive signal 102 or the feedback signal 101a may be used. This is because the frequencies of the drive signal 102 and the feedback signal 101a include temperature information of the vibrator 1. Further, an electrode different from the drive electrode is fixed to the surface of the vibrator 1 on which the drive electrode is disposed, and a signal extracted from the other electrode is replaced with the drive signal 103 to calculate a compensation amount. The input signals of the units 8 and 80 may be used. The above-mentioned matters regarding the signal source of the input signals of the compensation amount calculation units 8 and 80 are the same regardless of whether the leg shape of the vibrator 1 is U-shaped, quadruped, hexapoded, or the like. .

FIG. 2 is a functional block diagram showing a vibration gyro having a compensation amount calculation unit according to the first embodiment of the present invention. It is a functional block diagram which shows the vibration gyro which has a compensation amount calculating part of the 2nd Embodiment of this invention. 3 is a functional block diagram of a first embodiment showing a specific configuration example of a compensation amount calculation unit 8. FIG. 6 is a functional block diagram of a second embodiment showing a specific configuration example of a compensation amount calculation unit 80. FIG. It is a functional block diagram of the conventional vibration gyro which performs bias compensation by acquiring temperature data with a temperature sensor. It is a graph which shows the relationship between the temperature in a vibrator | oscillator, and the resonant frequency. It is a figure which shows the basic function of a vibration gyro, and is a functional block diagram of a gyro which does not have a compensation amount calculating part. It is a figure explaining the principle of operation of a tuning fork type vibration gyro having a structure in which a driving leg and a detection leg are coupled by a body part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrator 2 Self-excited oscillation part 3 Waveform shaping part 4 Phase shift part 5 AC amplification part 6 Synchronous detection part 7 DC amplification part 8, 18, 80 Compensation amount calculation part 9 Analog adder 10 Body part 10a Body upper surface 10b Body Bottom surface 10c, 10d Body end surface 10e, 10f Body side surface 15 Temperature sensor 81 Frequency measurement unit 82 Bias compensation amount calculation unit 83 Sensitivity correction calculation unit 101a Feedback signal 101b Detection signal 102 Drive signal 103 Waveform-shaped drive signal 104 Signal 105 Amplified detection signal 106 Detection signal 108, 118 Bias compensation amount signal 108b Correction phase amount signal 111a, 111b Excitation drive leg 112a, 112b Vibration detection leg 115, 181 Temperature signal ω Angular velocity ωa Angular velocity signal Ca, Cb Coriolis Vibration Ha, Hb Drive vibration Da, Db Detection vibration

Claims (4)

A vibrator, vibrator driving means for driving the vibrator using one resonance frequency of the vibrator as a drive signal, and means for detecting Coriolis vibration appearing in the vibrator according to an angular velocity received by the vibrator; A bias compensation amount generating means for generating a bias compensation amount for compensating a bias which is an output value of the Coriolis vibration detecting means when the vibrator does not receive the angular velocity; an output of the Coriolis vibration detecting means; A vibration gyro having a bias removing unit that generates an angular velocity signal that does not include the bias by combining with a bias compensation amount and removing the bias from the output of the Coriolis vibration detecting unit.
The bias compensation amount generating means generates the bias compensation amount according to the resonance frequency. The bias compensation amount generation means measures the resonance frequency and outputs a value corresponding to the measured frequency as temperature data of the vibrator, and a bias that generates the bias compensation amount based on the temperature data A compensation amount calculation unit,
The bias compensation amount calculation unit stores in advance a polynomial or a lookup table having a temperature as a variable, and obtains the bias compensation amount corresponding to the temperature data by the polynomial or the lookup table. The vibrating gyroscope according to Item 1. A vibrator, vibrator driving means for driving the vibrator using one resonance frequency of the vibrator as a drive signal, and means for detecting Coriolis vibration appearing in the vibrator according to an angular velocity received by the vibrator; Have
The Coriolis vibration detection means includes a phase shift unit that generates a reference signal by transferring the phase of the drive signal, and a synchronous detection unit that synchronously detects Coriolis vibration of the output of the vibrator using the reference signal. In vibration gyro,
A phase correction amount signal is generated based on a change in the resonance frequency, and the phase correction amount signal is supplied to the phase shift unit.
The phase amount correction means represents, as the phase correction amount signal, a phase having a magnitude sufficient to correct a variation amount of the phase difference between the Coriolis vibration and the reference signal caused by temperature fluctuation of the vibrator.
The phase shift unit shifts the phase of the reference signal by a phase correction amount represented by the phase correction amount signal. Bias compensation amount generating means for generating a bias compensation amount for compensating a bias that is an output value of the Coriolis vibration detecting means when the vibrator does not receive the angular velocity; an output of the Coriolis vibration detecting means; A bias removing unit that generates an angular velocity signal that does not include the bias by combining the bias compensation amount and removing the bias from the output of the Coriolis vibration detecting unit;
4. The vibration gyro according to claim 3, wherein the bias compensation amount generation unit acquires temperature data of the vibrator based on the resonance frequency and generates the bias compensation amount according to the temperature data.

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