JP2975262B2 - Vibrating gyroscope detection 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 vibrating gyroscope detecting circuit, and more particularly to stabilizing the performance of a vibrating gyroscope by removing a false signal component due to parasitic vibration from a detection signal and improving detection accuracy. The present invention relates to a vibration gyro detection circuit.

[0002]

2. Description of the Related Art As is well known, a vibration gyroscope is
It detects angular velocity by detecting sub-vibration caused by Coriolis force induced by main-direction vibration. The vibratory gyroscope is extremely inexpensive compared to the inertial gyroscope and the optical fiber gyroscope. And a change in a parasitic signal caused by a manufacturing error. For this reason, there has been a problem that a drift occurs in the detection signal of the vibration gyroscope, and the sensor function deteriorates.

[0003] Conventionally, attempts have been made to solve this problem. For example, in Japanese Patent Laid-Open No. 3-172714, two synchronous detection circuits are provided to correct a change in sensitivity due to a detection phase shift. .

[0004]

However, the above-mentioned prior art is effective when the detected signal to be synchronously detected is composed of only a signal component proportional to the angular velocity, but is proportional to the angular velocity. It is not very effective in removing a parasitic wave component called a null wave included in the test wave signal composed only of the signal component. The reason is that the null wave itself is synchronously detected and remains in the detection signal of the final output.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems of the prior art, to accurately remove null waves even when there is a temperature change, and to effectively suppress drift due to temperature or the like. It is to provide a circuit.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an apparatus for detecting an angular velocity from vibration in a sub-direction perpendicular to the main direction, which is generated when a gyro vibrating element is vibrated in a main direction. In a vibrating gyro detection circuit for detecting, a feedback signal obtained from the gyro vibrating element is phase-shifted by an amount of phase in which a parasitic wave (null wave) is shifted by a temperature change, and transferred by the phase shifting means. And a detection circuit for detecting a detection signal generated by the sub-direction vibration using the feedback signal as a detection signal.

[0007]

According to the present invention, even if the null wave is shifted in phase due to a change in environmental temperature, the feedback signal serving as a detection signal always has a predetermined phase relationship with the null wave.
The null wave is completely canceled when the detection signal is detected by the detection circuit. For this reason, even if there is a temperature change, the null wave can be accurately removed, and drift due to temperature or the like can be effectively suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a vibration gyro detection circuit according to one embodiment of the present invention. In the figure, reference numeral 1 denotes a gyro vibrating element having a sectional shape of a square, a triangle, a circle, or the like, or a tuning fork type. The gyro vibrating element 1 is provided with a drive electrode 2, a main direction vibration detection electrode (feedback electrode) 3, and sub-direction vibration detection electrodes 4 and 5.

An FB signal output from a feedback electrode (hereinafter abbreviated as FB electrode) 3 is input to a self-excited oscillation circuit 6 and a phase correction circuit 8 of a detection signal generation circuit 7 via a voltage follower including an operational amplifier. The self-excited oscillation circuit 6 amplifies the FB signal, performs a phase shift process, and supplies the FB signal to the drive electrode 2 as a drive voltage.

As shown in FIG. 2, the phase correction circuit 8 uses a temperature-sensitive element 8a as an input-side resistor. In the phase correction circuit 8, the magnitudes of the capacitors and the resistors are changed to C1, C2, R1 and
Assuming that the self-excited vibration frequency is f, 2πfC2 R
Assuming that 2 = 1 / 2πfC1 R1, the ratio Vo / Vi of the input signal to the output signal and the phase θ are as follows.

[0011]

(Equation 1) In the phase correction circuit 8, the phase θ
Changes in proportion to the rate of change .DELTA.R1 / R1 of the resistor R1. The FB signal whose phase has been corrected by the phase correction circuit 8 is input to a synchronous detection circuit 9 via a charge amplifier including an operational amplifier. In this embodiment, the synchronous detection circuit 9 is a MOS FET
The FB signal is input to the gate of the MOS FET.

On the other hand, the sub-direction vibration detecting electrodes 4 and 5
Is amplified by a differential amplifier 10, synchronously detected by a synchronous detection circuit 9, and input to a smoothing amplifier 11.

Next, the operation of the main part of this embodiment will be described.
This will be described with reference to FIGS. In these figures,
(a) shows a detected signal, (b) shows a signal component to be detected, and (c) shows a waveform of a null component to be detected. The detection signal a is a signal input to the synchronous detection circuit 9 in FIG. 1, and the detection signal component b and the detection null wave component c are waveforms of the output signal of the differential amplifier 10.

FIG. 3 shows the waveform of each signal when there is no temperature drift. At this time, the phase relationship between the detected signal a and the detected null wave component c is shifted by 90 ° as shown. Therefore, during the detection period, that is, during the period when the detection signal a is positive, the detected null wave component c is canceled by the positive and negative components,
A detection signal containing no null wave component is supplied to the smoothing amplifier 11.

Here, when a temperature drift occurs in the vibration gyroscope, as shown in FIG.
The null wave component c to be detected is shifted in phase by Δθ, and the phase difference with the detection signal a is not 90 °. Therefore, in the present embodiment, assuming that the phase correction circuit 8 does not exist, the synchronous detection circuit 9 performs synchronous detection using the detection signal a whose phase is not corrected, so that the detected null wave component c is positive and negative as shown in the figure. The components are synchronously detected without being canceled by the above components, and a null wave component is mixed into the detection signal.

However, in this embodiment, since the phase correction circuit 8 is provided, the detection signal a is shifted by Δθ by the phase correction circuit 8 as shown in FIG. As a result, the detected null wave component c is canceled by the positive and negative components again by the synchronous detection, and a detection signal containing no null wave component is supplied to the smoothing amplifier 11.

The temperature sensing element 8a is an element having such a characteristic that the phase correction circuit 8 shifts the phase of the detection signal a by the temperature drift amount of the null wave component c to be detected in accordance with the environmental temperature. Of course there is.

As described above, according to the present embodiment, when a temperature drift occurs in the vibrating gyroscope, the detection signal a is also shifted in phase by the same amount Δθ as the phase shift of the detected null wave component c. , The test wave null wave component c
Disappears during synchronous detection, and a highly accurate detection signal can be obtained. In general, most of the detected signal is a null wave based on a manufacturing error. In other words, as is clear from FIG. 3, the signal component of the detected signal is much smaller than the null component. Therefore, automatically adjusting the phase of the detection signal using the temperature sensing element is very effective in reducing drift. Further, when the signal is corrected by the phase correction circuit 8, the amplitude slightly changes as is clear from the above equation. However, in the present embodiment, since the detected signal is not the detected signal but the amplitude, the synchronous detection has almost no adverse effect, and the null wave component is integrated and canceled by the detection. The amplitude of the signal component is unchanged. Therefore, a highly accurate detection signal can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, 20 is a phase correction circuit, 21
Indicates a smoothing circuit, and other reference numerals indicate the same or equivalent components as those in FIG.

In this embodiment, the point that the temperature sensing element 8a is used as the feedback resistor of the phase correction circuit 20, and that the self-excited oscillation circuit of the drive electrode 2 is formed by the phase correction circuit 20 and the smoothing circuit 21. There is a feature.

The temperature-sensitive element 8a of the phase correction circuit 20 changes its resistance value when the environmental temperature changes. For this reason, the phase correction circuit 20 shifts the phase of the FB signal output from the FB electrode 3 by Δθ and outputs it to the synchronous detection circuit 9.
As a result, similarly to the first embodiment, the null wave component c to be detected can be eliminated at the time of synchronous detection, and a highly accurate detection signal can be obtained. In this embodiment, since the self-excited oscillation circuit of the drive electrode 2 is formed by the phase correction circuit 20 and the smoothing circuit 21, the amplitude of the drive voltage applied to the drive electrode 2 slightly varies. There is an advantage that the circuit can be configured with a smaller number of circuit elements and at lower cost than in the first embodiment.

Although the above embodiment has been described with reference to the example using the piezoelectric gyro vibrating element 1, the present invention is not limited to this, and a gyroscope driven by electrostatic force and driven by thermal stress. Needless to say, the present invention can be applied to a gyroscope or a gyroscope driven by an electromagnetic force.

[0023]

As is apparent from the above description, according to the first to fifth aspects of the present invention, the phase shift between the null wave, which is the main cause of the drift, and the synchronous detection signal is corrected, and the corrected synchronous Since the detected signal is detected by the detected signal, a null wave can be removed from the detected signal, and a highly accurate vibration gyro detection circuit can be provided.
Further, it is possible to effectively reduce adverse effects due to temperature drift, which is a problem in the vibration gyroscope.

According to the third aspect of the present invention, inexpensively,
The vibration gyro detection circuit of the present invention can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of the phase correction circuit of FIG.

FIG. 3 is a waveform diagram showing waveform examples of a detected signal, a detected signal component, and a null component when there is no drift.

FIG. 4 is a waveform diagram showing a waveform example of a detection signal and a null wave component when there is a drift and there is no phase correction circuit.

FIG. 5 is a waveform diagram showing a waveform example of a detection signal and a null wave component when there is a drift and a phase correction circuit is provided.

FIG. 6 is a circuit diagram showing a configuration of a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gyro vibration element, 2 ... Drive electrode, 3 ... Main direction vibration detection electrode (feedback electrode), 4 ... Sub-direction vibration detection electrode, 6 ... Self-excited vibration circuit, 7 ... Detection signal generation circuit,
8: phase correction circuit, 9: synchronous detection circuit, 10: differential amplification circuit, 11: smoothing amplification circuit, 20: phase correction circuit, 21
... Smoothing circuit.

Continuation of front page (56) References JP-A-4-295716 (JP, A) JP-A-4-297874 (JP, A) JP-A-5-297677 (JP, A) JP-A-5-302833 (JP, A) JP-A-60-188809 (JP, A) JP-A-4-273013 (JP, A) JP-A-3-48714 (JP, A) JP-A-61-20810 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01C 19/56 G01P 9/04

Claims (5)

(57) [Claims] 1. A vibration gyro detection circuit for detecting an angular velocity from a vibration in a sub-direction perpendicular to the main direction generated when the gyro vibration element is vibrated in a main direction, wherein the gyro vibration element is obtained from the gyro vibration element. Means for shifting the feedback signal by a phase amount by which a parasitic wave (null wave) is shifted by a temperature change; and generating the detection signal using the feedback signal transferred by the phase shifting means, by the vibration in the sub-direction. A detection circuit for detecting the detected signal, wherein a residual component after detection of a null wave included in the detection signal is removed. 2. The vibration gyro detection circuit according to claim 1, wherein a feedback signal before being phase-shifted by said phase shift means is supplied to a self-excited oscillation circuit, and said self-excited oscillation circuit causes said gyro-oscillation element to be driven. A vibration gyro detection circuit, wherein a drive signal for causing vibration in a main direction is generated. 3. The vibration gyro detection circuit according to claim 1, wherein a self-excited oscillation circuit is configured by a phase shifter that shifts the phase of the feedback signal and a smoothing circuit, and the self-excited oscillation circuit is used by the self-excited oscillation circuit. A vibrating gyro detection circuit, which generates a drive signal for vibrating in a main direction. 4. The vibration gyro detection circuit according to claim 1, wherein said phase shift means uses a temperature-sensitive element as an input resistance or a feedback resistance, and adjusts a phase of said detection signal in accordance with an environmental temperature. Is shifted by the temperature drift amount of the null wave. 5. The vibration gyro detection circuit according to claim 1, wherein the gyro vibration element is a piezoelectric drive type, an electrostatic drive type,
A vibration gyro detection circuit, which is one of a thermal stress drive type and an electromagnetic force drive type.