JPH06117860A - Vibratory gyro - Google Patents

Abstract

PURPOSE:To make a vibratory gyro to always make stable self-exciting vibrations and to detect the angular velocity of the gyro with high accuracy by giving three functions of a driving, feeding back, and detecting functions to a pair of piezoelectric elements. CONSTITUTION:By applying an AC voltage across piezoelectric elements 21 and 22 respectively stuck to side faces 1a and 1b of a vibrating body 1 from a driving device 7, a vibrator 6 is caused to make self-exciting vibrations in the X-axis direction. When the vibrator 6 makes the vibrations, the outputs of connecting sections 24 and 25 become the resultant outputs of the voltage supplied from the device 7 and voltage outputted from the elements 21 and 22. Therefore, when the sum of both resultant outputs are passed through a differential amplifier 27 and only the voltages generated from the elements 21 and 22 are extracted based on the vibrations in the X-axis direction, and then, the extracted voltages are fed back to the device 7 after both resultant outputs are added 26 to each other, the self-exciting vibrations of the vibrator 6 are stabilized. When the vibrator 6 is rotated around the Z-axis while the vibrator 6 makes the self-exciting vibrations, the vibrator 6 starts to make vibrations in the Y-axis direction due to a Coriolis force and a difference is generated between the output voltages of the connecting sections 24 and 25. Therefore, when both output voltages are amplified by means of a differential amplifier 8, the voltages resulting from the Coriolis force can be separately detected.

Description

Detailed Description of the Invention

[0001]

This invention relates to a pair of piezoelectric elements,
The present invention relates to a vibration gyro that makes it possible to always perform stable self-excited vibration and detection by exhibiting drive, feedback, and detection functions.

[0002]

2. Description of the Related Art Conventionally known vibration gyros are known, for example, as shown in block diagrams in FIGS. 4 and 5. In the vibrating gyro shown in FIG. 4, the driving piezoelectric element 2 is provided on one side surface of the vibrating body 1 having a rectangular cross section.
And the feedback piezoelectric element 3 on the opposite side surface facing the side surface, and the detection piezoelectric elements 4 and 5 on the other two side surfaces orthogonal to these. The vibrator 6 is formed by sticking the output, and while supplying the output from the driving device 7 to the driving piezoelectric element 2,
By feeding back the output of the feedback piezoelectric element 3 to the driving device 7, the vibrator 6 performs predetermined self-excited vibration in the X-axis direction of the orthogonal three-dimensional coordinate system. When the vibrator 6 is rotated around the Z axis under such self-excited vibration, the vibrator 6 is caused to vibrate in the Y axis direction due to the generation of Coriolis force, and this vibration in the Y axis direction occurs. The accompanying voltage
Since the voltage is generated in each of the detecting piezoelectric elements 4 and 5, the voltages are sequentially passed through the differential amplifier 8, the synchronous detector 9 and the DC amplifier 10, so that the angular velocity of the vibrator 6 is directly changed. Coriolis force is required as DC output.

Further, in the vibrating gyro shown in FIG. 5, driving piezoelectric elements 11 and 12 are attached to each of two side surfaces of a vibrating body 1 having a triangular cross-sectional shape, and the other side surface is used for returning. The piezoelectric element 3 is attached, and the output from the driving device 7 is applied to the driving piezoelectric element 1 via the resistors 13 and 14, respectively.
The vibrator 6 that is self-oscillated in the X-axis direction is configured by feeding back the output from the feedback piezoelectric element 3 to the driving device 7 while supplying the vibrations to 1 and 12. Here, the driving piezoelectric elements 11 and 12 which also function as detection piezoelectric elements
By differentially amplifying the voltage generated at, the DC detection is performed after the synchronous detection, the Coriolis force in the Y-axis direction generated by the rotation of the vibrator 6 around the Z-axis, and by extension,
The angular velocity can be detected.

[0004]

By the way, in the vibration gyro shown in FIG. 4, the respective piezoelectric elements 2, 3,
Since both 4 and 5 are adhered to the vibrating body 1 by an epoxy resin or other adhesive, for example, the driving piezoelectric element may change due to changes in the adhesive strength, elastic properties, etc. due to changes in ambient temperature. There is a problem that the characteristic difference between the piezoelectric element 3 for feedback and the feedback piezoelectric element 3 changes, and the vibration condition fluctuates, so that the self-excited vibration of the vibrator 6 becomes unstable. Also, when a temperature cycle is added,
There is also a problem that the properties of the adhesive change with time and a hysteresis occurs in the driving condition. Furthermore, the detection piezoelectric element 4,
There was also a problem that the change in the adhesive strength of No. 5 also causes the drift.

Further, due to variations in the characteristics of the piezoelectric elements 2, 3, 4, 5 and the asymmetry of the sectional shape of the vibrating body 1,
Ideally, vibration in the Y-axis direction, which does not occur when the vibrator 6 is not rotating, actually occurs, causing a so-called leakage voltage. However, there is a problem in that the magnitude of the leakage voltage also changes depending on the driving voltage and other driving conditions and causes drift. Further, in the case of this conventional technique, there is another problem that the work of assembling the vibrator 6 is extremely troublesome because each piezoelectric element needs to be bonded to each side surface of the vibrating body 1 with high accuracy.

In the prior art shown in FIG. 5, the driving piezoelectric elements 11 and 12 connected to the driving device 7 through the resistors 13 and 14 also function as detection piezoelectric elements. The change in leakage voltage due to the change in adhesive can be reduced more than that of the prior art shown in FIG. However, also in this conventional technique,
Since the feedback piezoelectric element 3 is separately provided like the one shown in FIG. 4, the same problem as described above remains with respect to the vibration condition.

An object of the present invention is to solve the above problems of the prior art in an advantageous manner, and to drive, return and detect a pair of piezoelectric elements without specially providing a return piezoelectric element. By functioning as each piezoelectric element for vibration, the assembly work of the vibrator is facilitated and the fluctuation of the vibration condition and the driving condition due to the influence of the adhesive is effectively reduced, and the change of the leakage voltage is sufficiently small. A vibration gyro that can be suppressed is provided.

[0008]

A vibrating gyroscope according to the present invention has a first piezoelectric element attached to a first side surface of a vibrating body having a polygonal transverse cross section and parallel to the first side surface. A second piezoelectric element is attached to a second side surface that does not become a vibrator to form a vibrator, and each of the first and second piezoelectric elements of the vibrator is connected to one of the vibrators via an impedance element. When connected to the vibration driving means, the connecting portion between each piezoelectric element and the impedance element is connected to the driving means through, for example, an adder and a differential amplifier that performs differential between the added output and the reference AC voltage in order. On the other hand, while connecting, each of the connection parts is also connected to a differential amplifier that differentially outputs the outputs of the connection parts, or a connection part of each piezoelectric element and an impedance element, for example, Output of connection A differential amplifier that performs a differential between the two and another differential amplifier that performs a differential between a differential output and a reference AC voltage are sequentially connected to the driving means, and each of the connection parts is also connected to an adder. It is connected.

Further, in another vibrating gyroscope of the present invention, the first piezoelectric element is attached to the first side surface of the vibrating body having a polygonal transverse cross section, and the vibrating body is not parallel to the first side surface. A second piezoelectric element is attached to the second side surface to form a vibrator, and each of the first and second piezoelectric elements of the vibrator is connected to one of the vibrators via the impedance element. When connected to the driving means, the connection portion between each piezoelectric element and the impedance element is sequentially driven through each differential amplifier and adder that performs the differential between the output of each connection portion and each reference AC voltage. On the other hand, each of the connection parts is also connected to a differential amplifier that differentially outputs the outputs of the connection parts, or a connection part of each piezoelectric element and an impedance element is connected to each connection. Output and each reference AC power The differential amplifiers and the adders that perform differential with each other are sequentially connected to the driving means, and the differential amplifiers are connected to each other and the differential outputs of the differential amplifiers are mutually differential. It is also connected to another differential amplifier for performing.

In each of the above-mentioned vibration gyros, more preferably, each reference AC voltage is a voltage at a connecting portion between the capacitive element connected to the driving means via the impedance element and the impedance element.

[0011]

When a stress is applied to the piezoelectric element, the piezoelectric element generates strain and the piezoelectric effect causes an electric displacement proportional to the stress. When an electric field is applied, the piezoelectric element causes an electric displacement and the inverse piezoelectric effect causes a proportional electric field. Strain. Therefore, when an AC voltage is applied to the piezoelectric element through the impedance element, the applied AC voltage and the voltage generated due to the distortion of the piezoelectric element are combined at the connection portion between the piezoelectric element and the impedance element. Voltage is observed.

Therefore, in the vibrating gyroscope of the present invention, by applying an AC voltage to a pair of piezoelectric elements attached to two side surfaces of the vibrating body which are not parallel to each other, self-excited vibration of the vibrator is caused and It was decided that the pair of piezoelectric elements have three functions of drive, feedback, and detection by separating and extracting the voltage generated by the strain of the piezoelectric element in each direction in each strain direction.

As a result, in the vibrating gyroscope of the present invention, the influence of the adhesive on the vibration condition and the driving condition is reduced to bring about stable self-excited vibration of the vibrating body, and when a temperature cycle is applied. Also, it is possible to suppress the occurrence of hysteresis in the driving condition, and to suppress the change in the leakage voltage to be sufficiently small. Furthermore, according to the vibrating gyroscope of the present invention, it suffices to attach the pair of piezoelectric elements to the vibrating body, so that the work of assembling the vibrator can be performed extremely simply and quickly.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, in which the same parts as those described in the prior art are designated by the same reference numerals. In this specific example, the first piezoelectric element 21 is provided on one side surface 1a of the vibrating body 1 having a triangular cross section.
And the other side surface 1b adjacent to the side surface 1a.
By attaching the second piezoelectric element 22 to the vibrator 6,
, And their respective piezoelectric elements 21, 22
Is connected to the driving device 7 via the impedance elements Z ₁ and Z ₂ respectively, and the driving device 7 is also connected to the capacitance element 23 via another impedance element Z ₃ so that the driving device 7 AC voltage from both piezoelectric elements 2
It is possible to apply the voltage to both 1, 22 and the capacitive element 23 at the same time.

On the other hand, each of the impedance element elements Z ₁ ,
Z ₂ and the connecting portions 24 and 25 between the piezoelectric elements 21 and 22, respectively,
It is connected to the differential amplifier 27 via the adder 26, and the adder 26 adds the outputs from both the connection parts 24 and 25, and in the differential amplifier 27, the impedance element Z ₃ and the capacitive element 23 are connected. The output from the connection section 28 and the output from the adder 26 are differentially amplified, and the differential output therefrom is fed back to the drive unit 7.

By the way, as each of the impedance elements Z ₁ , Z ₂ and Z ₃ herein, any type of resistance type, capacitance type and inductive type can be used. And further, each impedance element
Connection parts 24, 25 between Z ₁ , Z ₂ and the respective piezoelectric elements 21, 22
Is connected to another differential amplifier 8, and this differential amplifier 8 is sequentially connected to the synchronous detector 9 and the DC amplifier 10 as in the prior art.

According to the vibrating gyroscope constructed as described above, the vibrator 6 can be caused to self-oscillate in the X-axis direction by applying an AC voltage from the driving device 7 to the respective piezoelectric elements 21 and 22. it can. In such an oscillating state, the outputs from the respective connecting portions 24 and 25 are output from the respective piezoelectric elements 21 and 22 in accordance with the voltage supplied from the driving device 7 and the strain of the respective piezoelectric elements 21 and 22. It is a composite output with the applied voltage. Therefore, after adding both of these combined outputs in the adder 26, they are passed through the differential amplifier 27 to extract only the voltage generated from the piezoelectric elements 21 and 22 based on the vibration in the X-axis direction, Then, by feeding it back to the driving device 7, the self-excited vibration of the vibrator 6 can be made sufficiently stable.

When the vibrator 6 is rotated around the Z axis under such self-excited vibration, the vibrator 6 moves in the Y axis direction based on the Coriolis force. Vibration is generated, which causes a difference in the output voltage of the connection portions 24 and 25. Therefore, by differentially amplifying both of these output voltages by the differential amplifier 8, it is possible to separately detect the voltage associated with the generation of the Coriolis force.

FIG. 2 shows a modification of the embodiment shown in FIG. 1, in which the polarization direction of either one of the piezoelectric elements 21a, 22a attached to the respective side faces 1a, 1b of the vibrating body 1 is changed. , Which is the reverse of that shown in FIG. 1, whereby the strain and the output voltage are mutually reversed between the piezoelectric elements 21a and 22a. Therefore, differentiating the outputs of the respective connection parts 24a and 25a has the same meaning as adding in the example shown in FIG. 1, and adding these outputs is different in FIG. It has the same meaning as moving.

Therefore, each impedance element
Z _1, and Z _2, each of the piezoelectric elements 21a, 22a and the connecting portion 24a,
25a is connected to a differential amplifier 29 which differentiates the outputs from those connections 24a, 25a from each other, and this differential amplifier 29
Is connected to the drive device 7 via a differential amplifier 27 that differentially outputs a differential output from the reference AC voltage, and both connection portions 24a and 25a thereof are connected via an adder 30 to a synchronous detector. Connect to 9. In addition, here, each piezoelectric element 21a, 2
It is assumed that one of the phases of the drive voltage supplied to 2a is inverted by 180 degrees. It is needless to say that such a vibration gyro can bring about the same operation as that described with reference to FIG.

FIG. 3 is a block diagram showing another embodiment of the present invention. In this example, the driving device 7 is connected to each piezoelectric element via each impedance element Z ₁ and Z _2.
21 and 22, and also connected to the respective capacitive elements 31 and 32 via the other respective impedance elements Z ₄ and Z ₅ , and the respective connection parts 24 and 25 to the difference from the reference AC voltage. The present embodiment is different from the embodiment shown in FIG. 1 in that it is connected to the adder 25 via respective differential amplifiers 33 and 34 which operate.

Here, the differential amplifier 33 includes the output from the connecting portion 36 of the impedance element Z ₄ and the capacitive element 31, and the connecting portion
The output from 24 is differentially amplified, and the differential amplifier 34 differentially amplifies the output from the connecting portion 37 between the impedance element Z ₅ and the capacitive element 32 and the output from the connecting portion 25. Further, the adder 35 separates and detects only the voltage generated by the vibration of the vibrator 6 in the X-axis direction by adding the two differential amplified outputs, and feeds back the detected voltage to the drive device 7. Thus, stable self-excited vibration of the vibrator 6 is brought about.

In such a vibrating gyro, the Coriolis force during rotation of the vibrator 6 is generated by the respective connecting portions 24,
The output of 25 is input to another differential amplifier 8 and differentially detected, so that the differential detection can be performed.

In the above-mentioned place, the connecting portions 24, 25
Although the output of the differential amplifier 8 is directly input to the differential amplifier 8, the output from the differential amplifiers 33 and 34 is input to the differential amplifier 8 as in the case of FIG. It is possible to detect the Coriolis force and eventually the angular velocity. Further, in the present invention, the cross-sectional shape of the vibrating body 1 may be any polygonal shape other than the triangular shape.

[0025]

As is apparent from the above description, according to the present invention, by providing the piezoelectric elements on the two side surfaces of the vibrating body which are not parallel to each other, the feedback piezoelectric element is specially provided. It is possible to always provide stable self-excited vibration, and to detect the angular velocity with high accuracy, without providing the above. That is, by making the pair of piezoelectric elements perform the three functions of driving, returning, and detecting, the influence of the adhesive on the driving condition can be sufficiently reduced, and the driving condition when the temperature cycle or the like is added is changed. The occurrence of hysteresis is effectively suppressed, and the change in leakage voltage is suppressed sufficiently small. As a result, stable self-excited vibration is always provided, and high detection accuracy can be secured.

Further, in this case, since the vibrator can be constructed only by sticking the pair of piezoelectric elements to the vibrating body 1, the vibrator can be assembled very easily and quickly.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a modified example of the example shown in FIG.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a block diagram showing another conventional example.

FIG. 6 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

1 Vibrating body 1a, 1b Side surface 6 Transducer 7 Driving device 8, 27, 29, 33, 34 Differential amplifier 9 Synchronous detector 10 DC amplifier 21, 21a, 22, 22a Piezoelectric element 23, 31, 32 Capacitive element 24, 24a, 25, 25a, 28, 36, 37 Connection 26, 30, 35 Adder Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ Impedance element

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[Procedure amendment]

[Submission date] June 16, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

Claims (5)

[Claims] 1. A first vibrating body having a polygonal cross section.
Of the first piezoelectric element on the side surface of the first piezoelectric element and the second piezoelectric element on the second side surface that is not parallel to the first side surface, respectively. Is connected to one vibration driving means via each impedance element, and the sum of the respective outputs of the connecting portion of each piezoelectric element and the impedance element is differentiated with the reference AC voltage and fed back to the driving means. On the other hand, a vibrating gyro, wherein the respective outputs of the connection section are taken out differentially with respect to each other. 2. A first vibrating body having a polygonal cross section.
Of the first piezoelectric element on the side surface of the first piezoelectric element and the second piezoelectric element on the second side surface that is not parallel to the first side surface, respectively. Is connected to one vibration driving means via each impedance element, the outputs of the connection portion of each piezoelectric element and the impedance element are mutually differentiated, and the differential output is different from the reference AC voltage. A vibrating gyro, wherein the vibrating gyro is characterized in that the output of the connecting portion is added and taken out while being moved and returned to the driving means. 3. A first vibrating body having a polygonal cross section.
Of the first piezoelectric element on the side surface of the first piezoelectric element and the second piezoelectric element on the second side surface that is not parallel to the first side surface, respectively. Is connected to one vibration driving means via each impedance element, each output of the connecting portion between each piezoelectric element and the impedance element is differentiated from the reference AC voltage, and the sum of each differential output is calculated. A vibrating gyro, wherein each output of the connecting portion is differentially extracted while being fed back to the driving means. 4. A first vibrating body having a polygonal cross section.
Of the first piezoelectric element on the side surface of the first piezoelectric element and the second piezoelectric element on the second side surface that is not parallel to the first side surface, respectively. Is connected to one vibration driving means via each impedance element, each output of the connecting portion between each piezoelectric element and the impedance element is differentiated from the reference AC voltage, and the sum of each differential output is calculated. A vibrating gyro, wherein each of the differential outputs is taken out while being differentially fed back to the driving means. 5. The voltage according to claim 1, wherein the reference AC voltage is a voltage of a capacitive element connected to a driving means via an impedance element and a voltage at a connecting portion of the impedance element. Vibration gyro described in.