JP3170881B2 - Gyro drift suppression circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyro drift suppression circuit, and more particularly to a gyro drift suppression circuit capable of detecting a rotational angular velocity. The present invention relates to a gyro drift suppression circuit.

[0002]

2. Description of the Related Art As a conventional vibrating gyroscope as a background of the present invention, for example, there has been a vibrating gyroscope using a vibrator in which a piezoelectric element is formed on each of three side surfaces of a triangular prism-shaped vibrator. In this vibrating gyroscope, for example, two piezoelectric elements are used for driving and detection, and another piezoelectric element is used for feedback.

In this conventional vibrating gyroscope, when a driving signal is supplied from one feedback piezoelectric element to two driving and detecting piezoelectric elements, the vibrating body vibrates. If the vibrator rotates with the vibrating body vibrating in this way, an output difference occurs between the two driving and detecting piezoelectric elements, and the rotational angular velocity is detected by an output signal corresponding to the output difference.

[0004]

However, in the conventional vibrating gyroscope, there is a possibility that an error occurs in an output signal due to a drift component generated due to a change in ambient temperature or the like, and an error occurs in a rotational angular velocity.

Therefore, the present inventor has devised a novel gyro that can suppress such a drift component. This novel gyro is a gyro including an angular velocity sensor, a signal generating circuit for generating an AC signal, and a synthesizing circuit for synthesizing the output of the angular velocity sensor and the AC signal generated by the signal generating circuit.

In this novel gyro, a signal corresponding to the rotational angular velocity to be detected and a drift component are output from the angular velocity sensor. Further, an AC signal is generated by the signal generation circuit. Further, the output of the angular velocity sensor and the AC signal generated by the signal generation circuit are synthesized by the synthesis circuit. When the rotational angular velocity is not applied to the angular velocity sensor, the signal corresponding to the rotational angular velocity to be detected is 0, and the output of the combining circuit is a composite signal of the drift component and the AC signal generated by the signal generating circuit. In this state,
When the combined signal is 0, the output of the angular velocity sensor is regarded as a drift component, and the drift component is detected. Then, by subtracting the correction signal corresponding to the drift component from the output of the angular velocity sensor, the drift component is suppressed.
Therefore, in the new gyro, the drift component can be suppressed. Therefore, if this new gyro is used, even if a drift component is included in the output of the angular velocity sensor, the rotational angular velocity can be detected with almost no error.

However, in this new gyro, a complicated circuit such as a signal generation circuit is used, so that the circuit configuration becomes complicated. Furthermore, in this new gyro, the drift component is corrected as the drift component when the combined signal obtained by combining the AC component generated by the signal generation circuit with the drift component is 0.
The AC signal area or the AC signal area is corrected and the minimum resolution of the sensitivity is deteriorated.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a gyro drift suppression circuit having a simple configuration and good resolution.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a gyro drift suppression circuit for suppressing a drift component from an output of a gyro. The gyro output is provided to one input terminal, and a substantially flat frequency characteristic is provided. And a second differential circuit provided with a gyro output at one input terminal and having a frequency characteristic on the high frequency side different from the frequency characteristic of the first differential circuit at a specific frequency as a boundary Circuit and
A comparison circuit for comparing the output of the first differential circuit with the output of the second differential circuit, and the output of the first differential circuit and the output of the second differential circuit compared by the comparison circuit And the correction signal corresponding to the output of the gyro when
A gyro drift suppression circuit including a sampling and holding circuit to be applied to the other input terminal of the first differential circuit and the other input terminal of the second differential circuit.

[0010]

The output of the gyro is applied to one input terminal of the first differential circuit. Similarly, the output of the gyro is also provided to one input terminal of the second differential circuit. Further, the output of the first differential circuit and the output of the second differential circuit are compared by the comparison circuit. Then, a correction signal corresponding to the output of the gyro when the output of the first differential circuit and the output of the second differential circuit compared by the comparison circuit are substantially the same is converted into the first difference by the sampling and holding circuit. The other input terminal of the driving circuit and the other input terminal of the second differential circuit.

Here, the case where the rotational angular velocity is not given to the gyro and the case where it is given will be described separately.

First, when the rotational angular velocity is not given to the gyro, the output of the gyro is only a drift component.
Since this drift component has a low frequency, the output of the first differential circuit and the output of the second differential circuit are substantially the same. Therefore, the correction signal corresponding to the output of the gyro, that is, the drift component at that time, is supplied to the other input terminal of the first differential circuit and the other input terminal of the second differential circuit by the sampling and holding circuit. In this case, even if the magnitude of the drift component changes, the magnitude of the correction signal also changes following the change. Therefore, the output of the first differential circuit is almost zero, which always suppresses the drift component.

On the other hand, when a rotational angular velocity is given to the gyro, the output of the gyro becomes a signal corresponding to the rotational angular velocity and a drift component. Since the signal corresponding to the rotational angular velocity has a high frequency, the output of the first differential circuit and the second
Output of the differential circuit. Therefore, the signal corresponding to the output of the gyro at that time is not supplied to the other input terminal of the first differential circuit and the other input terminal of the second differential circuit by the sampling and holding circuit. The correction signal corresponding to the drift component is given. Therefore, the output of the first differential circuit is a signal corresponding to the rotational angular velocity.

As described above, in the gyro drift suppression circuit, a signal in which the drift component is suppressed from the gyro output, that is, a signal corresponding to the rotational angular velocity is output from the first differential circuit.

[0015]

According to the present invention, since a complicated circuit such as a signal generation circuit is not used, a gyro drift suppression circuit having a simple configuration can be obtained. Moreover, in the gyro drift suppression circuit according to the present invention, when the rotational angular velocity is not given to the gyro, the magnitude of the correction signal changes following the change in the magnitude of the drift component. Wider and better resolution.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0017]

FIG. 1 is a block diagram showing an example of a vibrating gyroscope according to an embodiment of the present invention. FIG. 2 is a side view showing the vibrator of the vibrating gyroscope shown in FIG. 1 and its peripheral portion. The present invention relates to a gyro drift suppression circuit. In this embodiment, an example of a vibrating gyro using the same will be described.

The vibrating gyroscope 10 includes a vibrator 12 as an angular velocity sensor.
It includes a prism-shaped vibrator 14. The vibrating body 14 is made of, for example, elinvar, iron-nickel alloy, quartz, glass, quartz,
It is generally formed of a material that generates mechanical vibration, such as ceramic.

The vibrating body 14 has piezoelectric elements 16a, 16b and 16c formed at the centers of the three side surfaces. The piezoelectric element 16a includes a piezoelectric layer 18a made of, for example, porcelain.
0a and 22a are formed respectively. The electrodes 20a and 22a are made of, for example, gold, silver, aluminum, nickel, copper-nickel alloy (monel metal)
The electrode material is formed by a thin film technology such as sputtering or vapor deposition, or by a printing technology depending on the material. Similarly, the other piezoelectric elements 16b and 16c
Also include piezoelectric layers 18b and 18c made of, for example, porcelain, and electrodes 20b and 22b and 20c and 22c are provided on both main surfaces of piezoelectric layers 18b and 18c, respectively.
c are formed respectively. And one electrode 20a-20c of these piezoelectric elements 16a-16c is
For example, it is bonded to the vibrating body 14 with an adhesive.

The portions near the two node points of the vibrating body 14 are supported by U-shaped support members 24a and 24b made of, for example, metal wires. The central portions of these support members 24a and 24b are fixed to the vicinity of two node points of the vibrating body 14, for example, by welding or bonding with a conductive paste. Further, these support members 24a and 24a
The end of 4 b is fixed to one main surface of the support plate 26.

In the vibrator 12, for example, two piezoelectric elements 16a and 16b are used for driving and detection, and another piezoelectric element 16c is used for feedback. When the output from the feedback piezoelectric element 16c is amplified and a drive signal is applied to the driving and detecting piezoelectric elements 16a and 16b, the vibrating body 14 vibrates, and the same vibration is generated from the piezoelectric elements 16a and 16b. A waveform is output. If the vibrator 12 rotates about its axis in that state, the output of one of the driving and detecting piezoelectric elements increases according to the rotational angular velocity, and conversely, the output of the other driving and detecting piezoelectric element increases. The output decreases with the rotational angular velocity.

Therefore, between the electrode 22c of the feedback piezoelectric element 16c of the vibrator 12 and the electrodes 22a and 22b of the driving piezoelectric elements 16a and 16b, the vibrator 12 is driven by self-excitation. The oscillation circuit 30 and the phase circuit 32 are connected as a feedback loop.

Further, the piezoelectric element 16a and the piezoelectric element 1
6b is connected to two input terminals of the differential circuit 40, respectively. Differential circuit 40 includes, for example, an operational amplifier,
The electrodes 22a and 22b of the piezoelectric elements 16a and 16b are connected to the non-inverting input terminal and the inverting input terminal of this operational amplifier.
Are connected respectively. This differential circuit 40 is for detecting the output difference between the piezoelectric elements 16a and 16b.

The output terminal of the differential circuit 40 is connected to the synchronous detection circuit 4
2 input terminals. The phase circuit 32 is connected to another input terminal of the synchronous detection circuit 42. The synchronous detection circuit 42 detects the output of the differential circuit 40 in synchronization with the drive signal of the vibrator 12.

Further, an output terminal of the synchronous detection circuit 42 is connected to an input terminal of the rectification amplification circuit 44. The rectifying and amplifying circuit 44 rectifies and amplifies the output of the synchronous detection circuit 42.

The rectifying amplifier circuit 44 of the vibrating gyroscope 10
Is connected to the first differential circuit 5 of the drift suppression circuit 50.
2 non-inverting input terminals. This first differential circuit 5
2 has a substantially flat frequency characteristic. for that reason,
The first differential circuit 52 outputs a signal obtained by subtracting the input to the inverting input terminal from the input to the non-inverting input terminal from the low frequency band to the high frequency band. The first differential circuit 52 includes a rectifying amplifier circuit 44 of the vibration gyro 10.
Is to subtract a correction signal corresponding to a drift component from the output of FIG.

Further, the output terminal of the rectifier amplifier circuit 44 is connected to the non-inverting input terminal of the second differential circuit 54. The second differential circuit 54 differs from the first differential circuit 52 in frequency characteristics on the high frequency side at a specific frequency.
In this embodiment, the second differential circuit 54 outputs an amplified signal in a high frequency band as compared with the first differential circuit 52.

The output terminal of the first differential circuit 52 and the output terminal of the second differential circuit 54 are connected to one input terminal and the other input terminal of the comparison circuit 56, respectively. The comparison circuit 56 is for comparing the output of the first differential circuit 52 with the output of the second differential circuit 54.

In this embodiment, when the input to one input terminal and the input to the other input terminal are substantially the same, for example, 1 / (1) of the power supply voltage Vcc (V) of the comparison circuit 56 2 Vcc / 2 (V). Therefore, when the output of the first differential circuit 52 and the output of the second differential circuit 54 are substantially the same, the comparison circuit 56 outputs Vcc / 2
(V) signal is output. When the input to one input terminal is smaller than the input to the other input terminal, the comparison circuit 56 outputs, for example, a signal of Vcc (V). Therefore, the output of the first differential circuit 52 is
Is smaller than the output of Vcc (V)
The signal of is output. Further, when the input to one input terminal is larger than the input to the other input terminal, the comparison circuit 56 outputs, for example, a signal of 0 (V). Therefore, when the output of the first differential circuit 52 is larger than the output of the second differential circuit 54, the comparison circuit 56 outputs a signal of 0 (V).

The output terminal of the comparison circuit 56 is connected to the input terminal of the sampling and holding circuit 58. The other input terminal of the sampling and holding circuit 58 is connected to the output terminal of the rectifying amplifier circuit 44 of the vibrating gyroscope 10. Further, the output terminal of the sampling and holding circuit 58 is connected to the inverting input terminal of the first differential circuit 52 and the inverting input terminal of the second differential circuit 54.

The sampling and holding circuit 58 is a rectifying and amplifying circuit of the gyro 10 when the output of the first differential circuit 52 and the output of the second differential circuit 54 compared by the comparing circuit 56 are substantially the same. The purpose of this is to provide a correction signal corresponding to an output of 44, that is, a drift component, to an inverting input terminal of the first differential circuit 52 and an inverting input terminal of the second differential circuit.

In this embodiment, the sampling and holding circuit 58 corresponds to the output of the rectifying and amplifying circuit 44, that is, the drift component only when the signal of Vcc / 2 (V) is input to the input terminal. Outputs a correction signal. In this case, if the magnitude of the drift component changes, the magnitude of the correction signal also changes following the change. The sampling hold circuit 58 has a V
When a signal other than the signal of cc / 2 (V), for example, a signal of Vcc (V) or a signal of 0 (V) is input, the correction signal in advance is held and output. In this case, the sampling and holding circuit 58 supplies the next Vcc / 2 to its input terminal.
The output of the correction signal is maintained until the signal (V) is input. When the next signal of Vcc / 2 (V) is input to the input terminal, the sampling and holding circuit 58 outputs a correction signal corresponding to the drift component at that time.

Next, the operation or operation of the vibrating gyroscope 10 will be described.

In the vibrating gyroscope 10, the output of the piezoelectric element 16c for feedback of the vibrator 12 is fed back to the driving and detecting piezoelectric elements 16a and 16b by the oscillation circuit 30 and the phase circuit 32 as a feedback loop. Drive self-excited.

Here, the case where the rotational angular velocity is not applied to the vibration gyro 10 and the case where the rotational angular velocity is applied will be described separately.

When no rotational angular velocity is applied to the vibrating gyroscope 10, a low-frequency drift component that increases with time is output from the output terminal of the rectifying and amplifying circuit 44, for example.

This drift component is supplied to the drift suppression circuit 5
0 is input to the non-inverting input terminal of the first differential circuit 52, the non-inverting input terminal of the second differential circuit 54, and the sampling and holding circuit 58.

Since this drift component has a low frequency, the output of the first differential circuit 52 and the output of the second differential circuit 54 are
It will be almost the same.

Therefore, the input to one input terminal of the comparison circuit 56 and the input to the other input terminal thereof become substantially the same, and the comparison circuit 56 outputs a signal of Vcc / 2 (V).

The Vcc / 2 (V) signal is input to the sampling and holding circuit 58. Therefore, the sampling hold circuit 58 is connected to the rectifying amplifier circuit 44 at that time.
, Ie, a correction signal corresponding to the drift component, and outputs it. In this case, even if the magnitude of the drift component changes, the magnitude of the correction signal also changes following the change.

The correction signal is input to the inverting input terminal of the first differential circuit 52 and the inverting input terminal of the second differential circuit 54. Therefore, the output of the first differential circuit 52 is almost always zero, in which the drift component is suppressed by the correction signal.

On the other hand, when a rotational angular velocity is given to the vibrating gyroscope 10, the output of the rectifying and amplifying circuit 44 becomes a high-frequency signal corresponding to the rotational angular velocity and a low-frequency drift component.

The output of the rectifying and amplifying circuit 44 is input to the non-inverting input terminal of the first differential circuit 52 of the drift suppressing circuit 50, the non-inverting input terminal of the second differential circuit 54, and the sampling and holding circuit 58. You.

Since the signal corresponding to the rotational angular velocity is high frequency, the output of the second differential circuit 54 is output from the first differential circuit 5.
2 output.

Therefore, the input to one input terminal of the comparison circuit 56 becomes smaller than the input to the other input terminal, and the comparison circuit 56 outputs a signal of Vcc (V).

The signal of Vcc (V) is input to the sampling and holding circuit 58, and the sampling and holding circuit 58 outputs a correction signal corresponding to the output of the rectifying and amplifying circuit 44 of the vibrating gyroscope 10, that is, the drift component. Continue to output.

The correction signal is input to the inverting input terminal of the first differential circuit 52 and the inverting input terminal of the second differential circuit 54. Therefore, the output of the first differential circuit 52 is a signal corresponding to the rotational angular velocity in which the drift component is suppressed by the correction signal.

As described above, in the drift suppression circuit 50, a signal in which the drift component is suppressed from the output of the rectification amplification circuit 44 of the vibration gyro 10, that is, a signal corresponding to the rotational angular velocity is output from the first differential circuit 52. Is done.

In the above embodiment, the second differential circuit for outputting the signal amplified in the high frequency band is used. Instead of this second differential circuit, the signal attenuated in the high frequency band is used. May be used. In this case, the outputs of the second differential circuit and the comparison circuit differ depending on the case, but the other circuits operate in the same manner as in the above-described embodiment.

In the above embodiment, the output terminal of the rectifying amplifier circuit 44 is connected to the non-inverting input terminals of the first differential circuit 52 and the second differential circuit 54, and the first differential circuit 52 The output terminal of the sampling and holding circuit 58 is connected to the inverting input terminal of the second differential circuit 54, and the sampling and holding circuit is connected to the non-inverting input terminal of the first differential circuit 52 and the second The output terminal of the circuit 58 may be connected, and the output terminal of the rectifying amplifier circuit 44 may be connected to the inverting input terminals of the first differential circuit 52 and the second differential circuit 54. In this case, the polarity is reversed, but the output of the first differential circuit 52 is a signal corresponding to the rotational angular velocity in which the drift component is suppressed by the correction signal.

Further, in the above embodiment, Vcc / 2
A comparison circuit that outputs a signal of (V), a signal of Vcc (V), or a signal of 0 (V) is used. Instead of this comparison circuit, the output of the first differential circuit and the second circuit are output. A comparison circuit that can detect that the output of the differential circuit is substantially the same as that of the differential circuit and that outputs another signal may be used. In this case, the sampling and holding circuit may be configured to operate with another signal output from the comparison circuit. Note that each of the comparison circuit and the sampling and holding circuit may be configured by combining a plurality of circuits.

In the above-described embodiment, a regular triangular prism-shaped vibrator is used as the vibrator of the vibrating gyroscope. However, a vibrator having another cross-sectional shape such as a quadrangular prism may be used. .

Although the vibration gyro has been described in the above embodiment, the drift suppression circuit according to the present invention can be applied to a gyro such as an optical fiber, a gas rate, and a top gyro other than the vibration gyro.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a vibrating gyroscope as one embodiment of the present invention.

FIG. 2 is a side view showing a vibrator of the vibrating gyroscope shown in FIG. 1 and a peripheral portion thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibration gyroscope 12 Vibrator 14 Vibrator 16a, 16b, 16c Piezoelectric element 24a, 24b Support member 26 Support plate 30 Oscillation circuit 32 Phase circuit 40 Differential circuit 42 Synchronous detection circuit 44 Rectification amplification circuit 50 Drift suppression circuit 52 First Differential circuit 54 Second differential circuit 56 Comparison circuit 58 Sampling and holding circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19/00-19/72 G01P 9/04 G01C 21/00

Claims (1)

(57) [Claims] 1. A gyro drift suppression circuit for suppressing a drift component from an output of a gyro, wherein the output of the gyro is provided to one input terminal, and the first differential circuit has a substantially flat frequency characteristic. A second differential circuit provided with an output of the gyro at one input terminal, and a frequency characteristic on a high frequency side different from a frequency characteristic of the first differential circuit at a specific frequency; A comparison circuit for comparing the output of the differential circuit with the output of the second differential circuit, and the output of the first differential circuit and the output of the second differential circuit compared by the comparison circuit. Sampling for providing a correction signal corresponding to the output of the gyro when the output is substantially the same to the other input terminal of the first differential circuit and the other input terminal of the second differential circuit Hold circuit A gyro drift suppression circuit.