JPS61258110A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To detect with a high accuracy an angular velocity of a rotating body by detecting a magnitude of the angular velocity and a direction of the angular velocity, from a ratio of a detecting signal obtained from a detecting element and a driving signal of the detecting element, and from a phase relation of the detecting signal and the driving signal, respectively. CONSTITUTION:A detecting element 1 has a driving part 2 and a detecting part 3, and rotates as one body with a rotating body. A driving circuit 4 supplies a driving signal VI to the driving part 2, and vibrates the detecting part 3. A signal VS which is detected 5 in accordance with a Corioli's force from the detecting part, generated thereby is brought to a full-wave rectification 11 through an amplifying circuit 9, and a DC voltage VS3 is outputted. An amplitude ratio of the voltage VS3, and a DC voltage VI4 obtained by half-wave-rectifying 10 and smoothing 13 the signal VI is detected by a logarithmic amplifying circuit (LAMP) 17, and on the other hand, as for the signal VI, the frequency is detected by a LAMP 16. An output VI3 of the circuit 17 and an output VL4 of the LAMP 16 are added 18, and the adding part 18 outputs a signal V01 corresponding to a magnitude of an angular velocity of the rotating body. On the other hand, a phase of an output VI3 of the half-wave rectifying circuit 10 and an output VS2 of the circuit 9 is detected 14, and a phase detecting circuit 14 outputs a signal VP for showing a direction of an angular velocity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an angular velocity sensor for detecting the angular velocity of a rotating body.

[Background of the invention]

In recent years, in fields such as automobiles and robots.

Demand for angular velocity sensors is increasing. Among these, vibrating types are attracting particular attention due to their longevity. An example of this vibration type Q angular velocity sensor is
Although disclosed in Japanese Patent No. 174854, this conventional example is for detecting 10,000 objects.

Two piezoelectric elements, the other of which is used for driving, are combined to form a pair, and the two piezoelectric elements of the pair are used to form a detection element χ in the shape of a tuning fork, and this detection element is connected to the rotating body to be measured. While rotating them together, these drive piezoelectric elements are vibrated with the same amplitude, the same frequency, and different phases to generate a Coriolis force in each detection piezoelectric element, and these Coriolis forces? The detection unit Φ detects the angular velocity Y of the rotating body contained therein by electrical processing. By configuring the detection element χ to Φ, the effects of linear vibration, acceleration, VCt, and acoustic vibration generated by the drive piezoelectric element are removed, and angular velocity can be detected with high accuracy.

However, the Coriolis force detected by the detection piezoelectric element depends on the vibration amplitude and vibration frequency of the drive piezoelectric element.
Furthermore, since these depend on the amplitude and frequency of the drive signal of the drive piezoelectric element, if the amplitude or frequency of this drive signal changes, the detected Coriolis force will also change, making it impossible to accurately detect the angular velocity.

So, what are the problems? In order to solve the problem, published by Senna Technology Editorial Department Information Research Committee: Sensor Device No.
1983, 11, 15) pP, 193-194 "49.
In the section "Angular Velocity Sensor", the police engineer introduced a technology that adopted an automatic gain control method to keep the amplitude of the drive signal constant in the drive circuit of the detection element, and installed a compensation capacitor to keep the frequency V constant. Disclosed.

However, in such conventional technology, the signal detected from the pipework, also from the detection piezoelectric element, depends on the vibration amplitude and vibration frequency of this piezoelectric element, and the amplitude and frequency of the drive signal cannot be accurately adjusted to the desired value. Since it is difficult to set, compensation is insufficient, and adjustment of the correction amount for automatic gain control is extremely difficult and requires a high degree of skill and effort. Furthermore, in order to detect the thickness and direction of the angular velocity of the rotating body from the signal detected from the detection piezoelectric element (this signal is synchronously detected, the reference clock for this is the drive No. 1 mentioned above and a predetermined voltage). Therefore, if the amplitude or frequency of the drive signal deviates from the desired value or fluctuates, the pulse width or phase of the reference clock will fluctuate, causing distortion. As a result, an error occurs in the magnitude of the obtained angular velocity.

[Purpose of the invention]

An object of the present invention is to solve the problems of the above-mentioned prior art, and to measure the angular velocity of a rotating body Q with high precision. An angular velocity sensor that can be detected? It is on offer.

[Summary of the invention]

To achieve this objective, the present invention calculates the magnitude of angular velocity from the ratio of the detection signal obtained from the detection element and the drive signal of the detection element. The present invention is characterized in that the direction of the angular velocity is detected and independently from this, the direction of the angular velocity is detected from the phase relationship between the detection signal and the drive signal.

[Embodiments of the invention]

First, the present invention will be explained with reference to FIG.

In a three-dimensional coordinate system consisting of the Y-axis, Y-axis, and Z-axis that are orthogonal to each other, on the X-Y plane consisting of the Y-axis and the Y-axis gZ-axis Y
An object M is rotating at an angular velocity Ω around the center, and the orbit drawn by this object M is a circular orbit with a radius R from the origin O, and this object M is also vibrating within the X-Y plane. Then, this object M is subjected to the following Coriolis force F in a direction perpendicular to its vibration direction and a direction parallel to the two axes.

occurs.

FC=zm (￥x7) Here, m tz The mass %v of the object M is the object M. 17) Velocity vector due to vibration, "7! H is an angular velocity transformation vector, and the direction is the Z-axis direction.Here, the object M is caused to vibrate greatly in the direction of the origin O, and the resulting Coriolis force Yc is generated in the tangential direction B-B/ of the rotating orbit.

Now, if the mass M is displaced (vibrated) in the direction A- by r sin ωt, then the magnitude of the Coriolis force fC is FC
is expressed by the following equation. Note that ω is 2πf, and f is the vibration frequency.

FC=2mΩr ωcos ωt -----
(1) In this equation, m, r, and ω simply indicate the size, but does the angular velocity Ω take a positive or negative value depending on the direction? I have it. Therefore, the Coriolis force FC has a phase with respect to r sin ωt representing the displacement of the mass M at the angular velocity Ω
Depending on the orientation, it will be delayed by 90 degrees or advanced by 90 degrees.

10,000, the radial Q force FA in the original vibration in the A-A/direction is Fh = mrω"sinωt.Furthermore, the centrifugal force FCL due to the angular velocity Ω is the radius R
, r71- "F1-, then FcL= mΩ"
(R+ rsiJ6) t). Therefore, A
The force F, which is generated in the direction of -, is: F, = FA + FcL; -mr(ω2-Ω") sincc
+t-1-mR122...(2) It becomes. Here, if we set ω〉Ω and extract the alternating current component of the force FT using a χ filter, then the direction F? □ is FTA-m r Q12sioωt =, pm. Therefore, the force FTA) represents the displacement of the two masses M and r
The phase is shifted by 180@ with respect to 5iflωt.

So, power FTAt? If we look at the Coriolis force FcY as a reference, its phase advances by 90° depending on the direction of the angular velocity Ω,
Also! Since the phase is delayed by 90 degrees, the direction of the angular velocity Ω can be detected by this phase χ detection section. Also, dividing the Coriolis Fcg) amplitude by the amplitude of the force FTA gives Φ. In addition, the power FTA si
By extracting ω from nωt and multiplying it, the magnitude of the angular velocity Ω can be detected regardless of fluctuations in the amplitude r and frequency f of the mass M.

The above is the principle of the present invention. Hereinafter, based on this principle, embodiments of the present invention will be described with reference to the drawings.

Is Fig. 1 an example of an angular velocity sensor according to the present invention? 1 is a block diagram showing a detection element, 2 a drive section, 3 a detection section, 4 a drive circuit, 5 a charge amplification circuit, 6, 7) an X bandpass filter, 8) an X phase shift circuit, 9 is an amplifier circuit, 1
0 is a half-wave rectifier circuit, 1 is a full-wave rectifier circuit, 12 is a frequency-voltage conversion circuit, 13 is a smoothing circuit, 14 is a phase detection circuit, 15 is a programmable multi-function remodule, 16 is a logarithmic amplifier circuit, 17 is a logarithmic ratio amplifier circuit,
184! Addition circuit, 19 is an anti-logarithm amplifier circuit, 20 is an inversion circuit, 21 is an analog switch, 22 is an amplifier circuit, 23
, 24 and 25 are output terminals.

In the same figure, the drive circuit 4 supplies a drive signal to the detection element IC1) drive section 21C to vibrate the detection section 3.

As shown in FIG. 2, the detection element 1 includes a driving section 2 made of a tuning fork-shaped piezoelectric element (crystal oscillator) and a detection section 3 made of a tuning fork-shaped piezoelectric element (crystal oscillator), respectively. The resonant waves 2A and 3A and the resonant waves 2B and 3B are joined together to form an integral structure. These piezoelectric elements are made by processing artificial quartz crystals into the same shape using photo-injection technology, but they are cut so that the mechanical axes of these crystals are orthogonal to each other. In the detection element l having such a configuration,
Add the angular velocity Ω to be detected in the warp length direction.

As shown in FIG. 3(a) vc, the drive unit 2 is provided with electrodes 26 and 27 made of aluminum evaporation on one surface of each of the resonant waves 2A and 2B, and the dividing line in FIG. 3(a) A cross section along C-C/? As shown in Figure 3(b), the sum,
Electrodes 26' and 27' are also provided on the other side of the resonant waves 2A and 2B, facing the electrodes 26 and 27. moreover,
I! As shown in FIG. 3(a), the tips of the resonant waves 2A and 2B (an adhesive material 28.degree. 29 made of a low melting point metal is provided).

Here, electrodes 26 and 27' shown in FIG. 3(b), electrode 2
7t26' are electrically connected, and the electrode 26
．． During the period 27, a drive signal is applied from the drive circuit 4, and the drive section 2 vibrates.

The distribution of this vibration is shown by the arrow 30 and broken line 31 in FIG. 3 (!l) when shown for two resonance waves.

On the other hand, the detection unit 3 detects FIG. 4(a) and its dividing line D-
FIG. 4 shows a cross section along D/ (as shown in bl, the electrodes 32 are connected to each other along the outer surfaces f! Further, an adhesive 34.3 of a low melting point metal is provided at the tip of the resonant waves 3A and 3B.
5 is provided b0 0B Resonance wave 2 of the drive unit 2 shown in Figure (a) 2 A I) Resonance wave of the detection unit 3 shown in Figure 4 [a] 3A (1) Tip and the adhesive material 28.34, and the tip of the resonant wave 2B cy) of the drive unit 2 and the tip of the detection unit 3 (1) are bonded with the adhesive 29.35, as shown in FIG. A detection element 1 is obtained. And drive! fl
s2 has an angular velocity Ω with the distribution shown by the arrow 30 and the broken line 31.
When vibrating in the direction perpendicular to the direction of (Fig. 2),
Detection T! i53, as shown in Fig. 4 f1), there are arrows 36. A Coriolis force Fc is generated in the direction and distribution indicated by the broken line 37. A voltage proportional to the Coriolis force FcTlc is obtained between the electrodes 32 and 33.

Returning to FIG. 1, the drive circuit 4 is the drive unit 2 configured in the above Q) J:5? The oscillation circuit Y is configured as an Il-resonant element, and therefore, the stiffness drive circuit 4 is designed to handle the rotational radial force FA and centrifugal force F of the drive element 1v explained earlier.
A driving voltage vlY proportional to the sum of forces F and r of CL is generated. This driving voltage x is vXoc-mr(ω2-Ω
")sinωt-4-mBΩ" - - (3) It is supplied to the drive section 2 of the detection element 1 and is also supplied to the bandpass filter 6 via the buffer Y in the drive circuit 4. Ru.

−10,000, as explained earlier, the above equation (1
) of the Coriolis force Fc, the electrode 32 of the detection 113
．． A charge is generated between 33 and 33. This charge is transferred to the charge amplification circuit 5
Vc is supplied, and its output voltage vs is supplied to the bandpass filter 7. Therefore, this voltage V8 becomes a voltage corresponding to the Coriolis force Fc. In other words, V soe 2 rr)Ωra+cosωt.

The band pass filter 6.7 is set to a center frequency Yf, and passes through the band pass filter 6 by Y of the component Vll of the first term of the equation (3) from the electrical voltage vX.
The band pass filter 7 allows the voltage to pass through with a delay of the same time as that of the band pass filter 6. Then, the band-pass filter 6f voltage v1□ is supplied to the phase shift circuit 8, and the band-pass filter 7 supplies the voltage V8t' to the amplifier circuit
supply to. Therefore, the voltage V11 has the following proportional relationship with each of v and 1t'z.

VIloc m, (ωx-Ωt) sinωt...
...-(4)V, 1 oe2mr ΩωC05(
c) f”
' Hoe・(5) Note that ω=2πf.

Next, the amplifier circuit 9 receives the voltage Vst'! 'Amplify voltage V8
□ Assuming this, the full-wave rectifier circuit 11 and the phase detection circuit 14
supply. Further, the phase shift circuit 8 sets the phase of the voltage Vll to approximately the same phase (or opposite phase) &CL as the voltage v8, and supplies the voltage VI2 to the half-wave rectifier circuit 10. The half-wave rectifier circuit 10 consists of a level shift section and an idealization diode section, and after attenuating the amplitude of the voltage v Circuit 13. and phase detection circuit 1
Furthermore, the full-wave rectifier circuit 11 consists of an absolute value circuit section and a smoothing section, and converts the voltage vs□ into a DC voltage V113.
Convert to This DC voltage V83 is programmable.
Multi-function fist module (manufactured by Analog Devices (1) 433 B) 15 log ratio amplification section 1
Supply to 7. Here, there is a linear proportional relationship between voltage and 3%.

V B s Oe 2mrΩω ---
--1(6) The frequency-voltage conversion circuit 2 forms a DC voltage vr proportional to the frequency f of the supplied voltage VXS, and supplies it to the logarithmic amplification section 16 of this module 15(1). Further, the smoothing circuit 13 smoothes the voltage to form a DC voltage VI4, which is supplied to the logarithmic ratio amplifying section 17 of the module 15. Here, the voltages vr and VX have a proportional relationship of less than 100 m. That is, v, ocω (°, °ω=2rf) ・−
・-・('7)v, 4ocmr(ω2-Ω2)
(8) In the module 15, the logarithmic ratio of the supplied voltages VB3 and VX4 is taken by the logarithmic ratio amplifying section 17 to form voltages VL and rx, which are added to the adding section 18.
supply to. On the other hand, the logarithmic amplifier 16 receives the supplied voltage
2 to form a voltage VL4v, which is supplied to the adder 18. The adder 18 converts both voltages v11 and VL4
A voltage VL5V is obtained by adding the voltage VL5, and this is supplied to the anti-logarithmic amplification section 19. Then, the anti-logarithmic amplification section 19 receives the voltage vL
The voltage V is obtained by performing anti-logarithmic transformation on s. ! Output. here,
Voltage V. ! Policeman.

0vRFj F
”9*n=1vd=v,,VzeVF1..
Vx=V,.

Shikatsu [, from the above equations (6)-(8), electric 1Evo!
It is expressed by a proportional relationship less than or equal to tz. In other words, V 0CIO2mrΩω 01 ] mr(ω−Ω).

By the way, as mentioned above, for the angular velocity Ω to be detected, if the vibration frequency f is set to a sufficiently high value (that is, ω
〉Ω), (ω!-, g can be approximated by ω8￥C. For example, if the angular velocity Ω is 0.01 degrees/sec and the vibration frequency f is 33KHz, then ω;2πf
, and if 2π is replaced with 360, it becomes approximately 12X10
'°/sec. Therefore, no problem arises even if the equation 5 is approximated as described above. Therefore, the above equation (9) becomes: 20 ω8 Ω−LΩ vol 9 (,,9).

[, the output voltage V of this module 15. 1 is supplied to the output terminal 254, the inverting circuit 20, and the analog switch 21. Then, the inverting circuit 20 receives the voltage V. ! Reverse the polarity and apply the voltage ■. ! 7 voltages o2Y: are supplied to the analog switch 21.

On the other hand, the phase detection circuit 14 consists of a synchronous detection section and a comparison section, and depends on the voltage VK3, the voltage v, 2? After performing synchronous detection and smoothing this synchronously detected voltage, the reference voltage (HaboOv) is obtained.
High level or rs fZlow level voltage V,r compared to
eOutput. Here, the voltage V13 is the voltage vX2'lk:
Some are half-wave rectified, voltage V12 + z above formula (4)
By the engineered phase shift circuit 8, V 1 z oe -111r (ω2-Ω2)cns
ωt becomes b6 and the voltage V, 2tzVs d (
Similarly to equation (5)), V8. oe 2 m rΩωcosωt, so depending on the direction of the angular velocity Ω, V B 20e 2
m r l Ω l ωcos ω 1
-Conflict・・Url jQ, 1 or 7%: ``I 820C-2m rIΩ1ωcosωt
---------Da. Therefore, voltage vs
3%t[EEv! Only the positive and negative (in-phase or negative phase) of the voltage vP obtained by synchronous detection with , are effective for detecting the direction of the angular velocity Ω.

By the way, when the drive section 2 or the drive circuit 4 is affected by the external environment and the amplitude and frequency of the drive signal fluctuate, the timing (time width and phase) of synchronous detection in the phase detection circuit 14 changes due to the characteristics of the circuit itself. fluctuate. Therefore, the level of the voltage V obtained by synchronous detection and smoothing (integration) also fluctuates. However, the voltage V8□, ■13
If the phase between
The voltage V, , g) can be determined as positive or negative, and therefore the direction of the angular velocity Ωυ can be detected once.

Now, the output voltage V of the phase detection circuit 14, +z output terminal 2
4 and the analog switch 21.

The analog switch 21 sets the voltage EEV0 and voltage V when the voltage EEvP is high, and the voltage V when the voltage EEvP is low. , Y is selected and the output voltage EEVo is set as the amplifier circuit 22.
supply to. The amplifier circuit 22 has a low-pass filter configuration and has a voltage of V. , V is amplified to obtain a voltage Vo4 v, which is supplied to the output terminal 23.

Therefore, the voltage VQ4k”L voltage 81:Vo(ocΩ
)? It is an amplified voltage whose polarity changes depending on the direction of the angular velocity Ωυ.

By the way, is it indicated by an analog meter? DojJ%&
Is the angular velocity Ω used in electronics EEvo, Y, computers, etc.? Detection, processing voltage V, and Mo! '! 'Use.

Note that the phase detection circuit 14g) synchronous detection section can be replaced with an analog multiplier and an integrator.

〔Effect of the invention〕

As explained above, according to the present invention, the detection signal corresponding to the Coriolis force obtained from the detection element is full-wave rectified, and the IC can efficiently obtain the amplitude @Y of the detection signal accurately. Since the magnitude of the angular velocity to be detected is detected based on the amplitude ratio of the voltage signal and the drive signal, the magnitude of the detected angular velocity t! It is possible to efficiently detect the drive signal without being affected by the amplitude, frequency and phase of the drive signal, or the mass of the vibrator constituting the detection element. Furthermore, the detection signal χ is used by the synchronous detection unit Φ to detect the Since the direction of the power angular velocity is detected, the detection result of the direction of the angular velocity is not affected even by a phase change over a relatively wide range between the detection signal and the drive signal. , an excellent device that can always detect angular velocity with high accuracy.

[Brief explanation of drawings]

FIG. 2 is a schematic configuration diagram showing an example Y of the detection element in FIG. 1, FIG. 3 is a perspective view showing the specific configuration of the drive section in FIG. 2, and FIG. is a sectional view taken along the dividing line C-C/ in Fig. 3 fa), I! Figure 4 (a) is a perspective view showing the specific configuration of the detecting section 6 in Figure 2, wc Figure 4 (bl G! Figure 5 is an N-embedded explanatory diagram of the present invention.
...Detection unit, 4...Drive circuit, 10...
... half-wave rectifier circuit, 11 ... full-wave rectifier circuit, 12 ... frequency-voltage conversion circuit, 13 ...
... Smoothing circuit, 14 ... Phase detection circuit, 16
...logarithmic amplifier circuit, 17...logarithmic ratio amplification circuit, 18...addition circuit, 19...
Anti-logarithm amplifier circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] a detection element that has a drive part and a detection part and rotates integrally with the rotating body; a drive means that supplies a drive signal to the drive part to vibrate the detection part; and a detection element that vibrates the detection part by supplying a drive signal to the drive part; full-wave rectification means for full-wave rectification of the detection signal; amplitude ratio detection means for detecting the amplitude ratio between the output signal of the full-wave rectification means and the drive signal; and frequency detection means for detecting the frequency of the drive signal. , comprising a multiplication means for multiplying the output signal of the amplitude ratio detection means and the output signal of the frequency detection means, and a phase detection means for detecting the phase of the detection signal based on the drive signal, the multiplication means An angular velocity sensor, characterized in that the angular velocity sensor is configured to output a signal corresponding to the magnitude of the angular velocity of the rotating body, and the phase detection means outputs a signal representing the direction of the angular velocity.