JPH08178670A - Vibration type angular velocity detector - Google Patents

Abstract

PURPOSE: To optimize the phase of a synchronous wave detection, and minimize the error of offset quantity by a temperature change. CONSTITUTION: A vibrator 11 has driving piezoelectric elements 12, 12b, detecting piezoelectric elements 13a, 13b, and reference piezoelectric elements 14a, 14b. An amplitude control circuit 22 supplies a signal for controlling the output amplitude of the reference piezoelectric elements 14a, 14b constant to the driving piezoelectric elements 12a, 12b through a phase shifting circuit 23. A synchronous wave detecting circuit 25 synchronously detects the output of the detecting piezoelectric elements 13a, 13b with the output signal of the phase shifting circuit 23 as a standard phase, and outputs the result as an angle speed signal. When the phase delay from the detecting piezoelectric elements 13a, 13b to the synchronous wave detecting circuit 25 is ▵θ1 deg., and the phase delay from the reference piezoelectric elements 14a, 14b to the synchronous wave detecting circuit 25 except the phase shifting circuit is ▵θ2 deg., the phase shifting quantity of the phase shifting circuit 23 is set to (90+▵θ1 -▵θ2 ) deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type angular velocity detector.

[0002]

2. Description of the Related Art A conventional vibration type angular velocity detector is, for example,
It is disclosed in Japanese Patent Application Laid-Open No. 62-52410, and this is intended to reduce the error due to the offset amount by shifting the output of the third piezoelectric element for detecting the vibration state of the vibrating body by 90 degrees for synchronous detection. Is. Specifically, as shown in FIG. 5, the driving piezoelectric elements 30a and 30b are feedback-controlled so that the output amplitudes of the reference piezoelectric elements 50a and 50b are constant, and the reference piezoelectric elements 50a and 50b are controlled. By synchronously detecting the outputs of the detection piezoelectric elements 40a and 40b by the synchronous detection circuit 130 based on a reference phase obtained by shifting the output phase by 90 degrees, an offset amount based on a characteristic change of the piezoelectric element due to a temperature change or the like, This is to prevent the error due to the offset amount due to the disturbance from being mixed in the angular velocity signal.

On the other hand, miniaturization is demanded as a recent social need, and miniaturization is also required for the vibration type angular velocity detector. In order to downsize the vibration type angular velocity detector, it is necessary to downsize the vibrating body.

[0004]

However, when the size of the vibrator is reduced, the mechanical resonance frequency also increases, and the phase delay in the processing circuit until the synchronous detection cannot be ignored. Then, as described above, the reference piezoelectric elements 50 a, 5
The output of 0b is accurately shifted by 90 degrees and the synchronous detection circuit 130
However, there is a problem that the error due to the offset amount due to the characteristic change of the piezoelectric element due to temperature change etc. cannot be minimized because there is a phase delay of the amplifier circuit in the previous stage, etc. Occurs.

Therefore, the present invention has been made in view of the above problems, and an error due to an offset amount due to a characteristic change of a piezoelectric element due to a temperature change or the like is mixed into an angular velocity signal by optimizing a reference phase of synchronous detection. An object of the present invention is to provide a vibration type angular velocity detector that suppresses the occurrence of vibration.

[0006]

The present invention is a vibrating angular velocity detector having a vibrating body and signal processing means for outputting a signal input from the vibrating body as an angular velocity signal. The above-mentioned first characteristic is that the vibrating body vibrates in such a manner that the vibrating body vibrates the vibrating body in the first vibrating direction and the vibration in the second vibrating direction perpendicular to the first vibrating direction of the driving means is detected. The detection means and the vibration reference means for detecting the vibration of the driving means in the first vibration direction are provided, and the signal processing means includes a phase shift means for shifting the phase of the output signal of the vibration reference means, and a phase shift means for the phase shift means. And a synchronous detection means for synchronously detecting the output of the vibration detection means with the output signal as a reference phase shift, and to set the phase shift amount of the phase shift means so as to cancel the phase delay caused by the signal processing means.

The second characteristic of the present invention is that the phase shift amount of the above-mentioned phase shift means is the phase delay from the vibration detection means of the vibrating body to the synchronous detection means of the signal processing means Δθ ₁ and degrees, when a phase delay △ theta ₂ degrees to the synchronous detection means, excluding the phase shifting means of the signal processing means from the vibration reference means of the vibrating _{body, (90 + △ θ 1 -} △ θ 2) so that the degree I have set it.

[0008]

As described above, by setting the phase shift amount of the phase shift means so as to cancel the phase delay by the signal processing means, the error due to the offset amount due to the characteristic change of the piezoelectric element due to the temperature change or the like is eliminated. It will be possible to minimize it. Further, the phase shift amount of the phase shift means is a phase delay from the vibration detection means of the vibrating body to the synchronous detection means of the signal processing means is Δθ ₁ degree, and the phase shift means of the signal processing means from the vibration reference means of the vibrating body is set. Phase delay to the synchronous detection means excluding
When θ ₂ degrees is set, (90 + Δθ ₁ −Δθ ₂ ) degrees are set so that synchronous detection can be performed with an optimum reference phase in consideration of the phase delay due to the amplification circuit of the signal processing means. It has an excellent effect of becoming.

[0009]

Embodiments of the vibration type angular velocity detector of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of an embodiment of the vibration type angular velocity detector of the present invention.
In FIG. 1, the vibration type angular velocity detector of this embodiment includes a vibrating body 10 attached to a movable body and an electric circuit 20 connected to the vibrating body 10. Vibrating body 10
Is a vibrator 1 with a tuning fork structure in which a quadrangular prism is formed in a U shape.
1 and a driving piezoelectric element 12 fixed to the vibrator 11.
a, 12b, detection piezoelectric elements 13a, 13b, and reference piezoelectric elements 14a, 14b.

The driving piezoelectric elements 12a and 12b are fixed to both side surfaces near the root of the vibrator 11, and by applying an AC signal, the vibrating body 10 is tuned in the tuning fork symmetrical direction (the left and right X axis directions in FIG. 1). Vibrate. Detection piezoelectric element 13a,
13b is fixed near the tip of the vibrator 11, and the vibrator 1
The vibration due to the Coriolis force generated when the angular velocity ω is applied around the Z axis in the length direction of 1 (Y in the figure is perpendicular to the paper surface).
(Axial direction) is detected to generate an angular velocity signal.

The reference piezoelectric elements 14a and 14b are fixed to both side surfaces near the tip of the vibrator 11, and the amplitude of the vibration of the vibrating body 10 in the tuning fork symmetrical direction (the left and right X-axis directions in the figure) is detected to detect the angular velocity. Generates a vibration reference signal required for detection of. The electric circuit 20 includes an amplifier circuit 21, 24, 27, an amplitude control circuit 22, a phase shift circuit 23, and a synchronous detection circuit 25.
And a low pass filter 26.

The outputs of the reference piezoelectric elements 14a and 14b are
The signal is amplified by the amplifier circuit 21 and supplied to the amplitude control circuit 22. The amplitude control circuit 22 compares the output amplitude of the amplifier circuit 21 with the reference voltage, and outputs a signal controlled so that the output amplitude of the amplifier circuit 21 becomes constant. Amplitude control circuit 22
The phase of the output of the phase shift circuit 23 is (90 + Δθ ₁ −
The driving piezoelectric elements 12a, 12 are phase-shifted by Δθ ₂ ) degrees.
applied to b. Thereby, the reference piezoelectric element 14a,
Driving piezoelectric element 1 so that the output amplitude of 14b is constant
2a and 12b are feedback-controlled, that is, the detecting piezoelectric element 13a by the vibration of the driving piezoelectric elements 12a and 12b,
Feedback control is performed so that the vibration amplitude of 13b is constant, and the vibrating body 10 self-oscillates at its mechanical resonance frequency.

The outputs of the detecting piezoelectric elements 13a and 13b are
The signal is amplified by the amplifier circuit 24 and supplied to the synchronous detection circuit 25. The output of the detection piezoelectric elements 13a and 13b has an angular velocity ω
The signal due to the vibration of the vibrating body 10 is also included in addition to the signal due to the vibration of the vibrating body 10, and the synchronous detection circuit 25 synchronously detects the output of the amplifying circuit 24 with the output of the phase shift circuit 23 as a reference phase. Signal is removed. The output of the synchronous detection 25 is smoothed by the low pass filter 26, amplified by the amplifier circuit 27 to have a predetermined sensitivity, and output as an angular velocity signal representing the angular velocity ω.

Here, the phase amount of the phase shift circuit 23 is (90
It is set as + Δθ ₁ −Δθ ₂ ) degrees. It should be noted that Δθ ₁ degree represents a phase delay from the output of the detection piezoelectric elements 13a and 13b to the input to the synchronous detection circuit 25, and Δθ ₂ degree represents the phase delay from the output of the reference piezoelectric elements 14a and 14b. The phase delay up to the synchronous detection circuit 25 excluding the phase circuit 23 is shown.

The operation of this embodiment configured as described above will be described. In the state of angular velocity ω = 0, the detecting piezoelectric element 1
Coriolis force acting vertically on 3a and 13b is not generated. However, the dimensional error of the vibrator 11 and the piezoelectric element for detection 1
An offset signal due to vibration is output from the detection piezoelectric elements 13a and 13b even in the state where the angular velocity ω = 0 due to an adhesion error of 3a and 13b. This signal has the same phase or opposite phase as the vibration reference signal output from the reference piezoelectric elements 14a and 14b.

On the other hand, the signals generated from the detection piezoelectric elements 13a and 13b are affected by the drive voltage applied to the drive piezoelectric elements 12a and 12b, and the offset signal due to the capacitive coupling is also superimposed. This signal is transmitted to the reference piezoelectric element 14
The phase is shifted by 90 degrees with respect to the vibration reference signals output from a and 14b. Both signals are output from the amplifier circuit 24.

Since the influence of the offset signal on the angular velocity signal is (offset signal due to vibration) >> (offset signal due to capacitive coupling), it is necessary to minimize the error with respect to the fluctuation of the offset signal due to vibration.

For that purpose, the phase difference between the reference phase signal in the synchronous detection circuit 25 and the offset signal due to the vibration may be accurately adjusted to 90 degrees. However, in reality, the synchronous detection circuit 2 is output from the outputs of the detection piezoelectric elements 13a and 13b.
A phase delay △ theta ₁ degrees to be input to 5, the difference between the phase delay △ theta ₂ degrees of the reference piezoelectric element 14a, from 14b to the synchronous detection circuit 25, except for the phase shift circuit 23 is generated, There is an error of (Δθ ₁ −Δθ ₂ ) degrees. Therefore, if the amount of phase shift of the phase shift circuit 23 is (90 + Δθ ₁ −Δθ ₂ ) degrees, the influence of the difference in phase delay between the two can be ignored, and there is no error in the fluctuation of the offset signal due to vibration. Can be

FIG. 2 is a diagram showing an embodiment of the phase shift circuit 23 of the present invention. The transfer characteristic of the phase shift circuit 23 is given by the following equation (1).

[0020]

[Number 1] _{v o / v i = (-} 1 + jωRC) / (1 + jωRC) Further, v v phase difference phi _PS of _o is for _i, is given by the formula for a number of 2.

[0021]

Φ _PS = tan ⁻¹ 2ωRC / ((ωRC) ² −1) Here, by changing R, the phase difference at each frequency ω can be changed. For example, if ωRC = 1, the phase difference φ _PS of v _o with respect to v _i is 90 degrees.

Next, an example of calculating Δθ ₁ and Δθ ₂ will be shown. Generally, the frequency characteristic of the open circuit voltage gain A of the operational amplifier circuit is
As shown in FIG. 3 shows a characteristic that the gain decreases with a slope that exceeds a predetermined gain A ₀ becomes, f ₀ to the frequency f _0. In addition, the operational amplifier circuit with negative feedback adjusts the feedback amount to β
Then, it can be represented by a block diagram as shown in FIG. The transfer characteristic of the block diagram of FIG. 4 is given by the following equation (3).

[0023]

Equation 3] _{v o / v i = A 0} / ((1 + A 0 β) + j (f / f 0)) The phase difference phi _C of v _o for v _i is given by the formula for a number of 4 .

[0024]

Φ _C = −tan ⁻¹ (f / f ₀ ) / (1 + A ₀ β) The formula 4 is applied to the amplifier circuit 21, the amplitude control circuit 23, and further to the amplifier circuit 24, and Δ It suffices to find θ ₁ and Δθ ₂ .

As described above, in the present embodiment, the synchronous detection circuit 2 is detected from the outputs of the detection piezoelectric elements 13a and 13b.
The phase delay up to 5 is Δθ ₁ degree, and the reference piezoelectric element 14
When the phase shift delay from the outputs of a and 14b to the synchronous detection circuit 25 excluding the phase shift circuit 23 is Δθ ₂ degrees, the phase shift circuit 2
By setting the phase shift amount of 3 to (90 + Δθ ₁ −Δθ ₂ ) degrees, synchronous detection can be performed at the optimum reference phase in consideration of the phase delay due to the amplifier circuits 21, 24, etc. It is possible to minimize the error due to the offset amount due to the characteristic change of the piezoelectric element due to the change or the like.

In the above embodiment, the vibrator 11
Although a prismatic tuning fork vibrator is shown as above, any vibrator capable of detecting angular velocity, such as a tuning piece vibrator, can be applied. Further, the circuit configuration may be any configuration as long as it is a circuit including the synchronous detection circuit 25. Further, the phase shift circuit 23 may have any configuration as long as it is a circuit capable of shifting the phase around 90 degrees.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a vibration type angular velocity detector of the present invention.

FIG. 2 is a diagram illustrating an example of a phase shift circuit.

FIG. 3 is a diagram showing characteristics of an operational amplifier circuit.

FIG. 4 is a block diagram of an operational amplifier circuit provided with a negative feedback circuit.

FIG. 5 is a diagram showing an overall configuration of a conventional vibration type angular velocity detector.

[Explanation of symbols]

10 ... Vibrating body, 11 ... Vibrator, 12a, 12b ... Driving piezoelectric element, 13a, 13b ... Detection piezoelectric element, 14a,
14b ... Reference piezoelectric element, 21, 24, 27 ... Amplifier circuit, 22 ... Amplitude control circuit, 23 ... Phase shift circuit, 25 ... Synchronous detection circuit, 26 ... Low-pass filter

Claims (2)

[Claims] 1. A vibrating angular velocity detector, comprising: a vibrating body; and a signal processing means for outputting a signal input from the vibrating body as an angular velocity signal, wherein the vibrating body is the first vibrating body. Driving means for vibrating in a direction, vibration detecting means for detecting vibration in a second vibration direction perpendicular to the first vibration direction of the driving means, and vibration reference for detecting vibration in the first vibration direction of the driving means The signal processing means synchronizes the output of the vibration detection means with the output signal of the phase shift means as a reference phase shift, and the phase shift means for shifting the phase of the output signal of the vibration reference means. A vibrating angular velocity detector, comprising: a synchronous detection means for detecting; and a phase shift amount of the phase shift means is set so as to cancel a phase delay caused by the signal processing means. 2. A phase delay from the vibration detection means of the vibrating body to the synchronous detection means of the signal processing means is Δθ ₁ degree, and the phase shift means of the vibration processing means of the vibrating body to the phase shift means of the signal processing means. When the phase delay to the synchronous detection means other than is Δθ ₂ degrees, the phase shift amount of the phase shift means,
The vibration type angular velocity detector according to claim 1, wherein the vibration type angular velocity detector is set to have a value of (90 + Δθ ₁ −Δθ ₂ ).