JP2566707B2 - Vibration gyro with diagnostic function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro which performs self-excited vibration, for example, a vibration gyro with a diagnostic function suitable for use in an attitude control system, a navigation system or the like mounted on an automobile or the like.

[0002]

2. Description of the Related Art Conventional vibration gyros of this type include:
For example, the one shown in FIG. 3 is known. In this vibrating gyroscope, a first piezoelectric element 2a is attached to one side surface 1a of a vibrating body 1 having a rectangular cross section, and a second piezoelectric element 2b is attached to another side surface 1b adjacent to the side surface 1a. To form the vibrator 3 and to form the piezoelectric elements 2a and 2b.
Are connected to the output side of the driving device 4 via the impedance elements Z ₁ and Z ₂ , respectively, and the capacitive element C is also connected to the output side of the driving device 4 via another impedance element Z _3. Thus, the driving device 4 simultaneously applies an AC voltage to both the piezoelectric elements 2a and 2b and the capacitive element C.

Further, here, the impedance element Z ₁ ,
Z ₂ and the piezoelectric elements 2a and 2b, respectively, at connection points 5a,
5b is connected to the input terminal of the adder 6, and the output terminal of the adder 6 and the connection point 5c of the impedance element Z ₃ and the capacitive element C are connected to the input terminal of the differential amplifier 7. The differential output from the differential amplifier 7 is fed back to the driving device 4. On the other hand, the impedance elements Z ₁ and Z ₂ and the piezoelectric element 2
The respective connection points 5a and 5b with a and 2b are also connected to the input terminal of the differential amplifier 8, and the differential output from there is
After being detected by the synchronous detector 9, it is smoothed by a smoothing circuit (not shown) and extracted as an angular velocity detection signal. The output of the driving device 4 is also supplied to the synchronous detector 9.

In this vibrating gyro, the vibrator 3 can be self-oscillated in the X-axis direction of the orthogonal three-dimensional coordinate system by applying an AC voltage from the driving device 4 to the piezoelectric elements 2a and 2b. In this vibration state, connection point 5
The outputs obtained from a and 5b are the supply voltage from the driving device 4, the vibrator 3, and the piezoelectric elements 2a and 5b, respectively.
Along with the distortion of 2b, it becomes a combined output with the voltage output from each of the piezoelectric elements 2a and 2b. Therefore, if the sum of the two combined outputs is obtained by the adder 6 and the difference between the output from the adder 6 and the output corresponding to the supply voltage from the connection point 5c is obtained by the differential amplifier 7, the X-axis is obtained. Since only the voltage generated from the piezoelectric elements 2a and 2b can be extracted based on the vibration in the direction, the output of the differential amplifier 7 is fed back to the driving device 4, so that the vibrator 3 is sufficiently stable and self-excited. Can be made.

When the vibrator 3 is rotated about the Z-axis under the condition that the vibrator 3 is self-excited as described above, the vibrator 3 is caused by Coriolis force proportional to the angular velocity. It also vibrates in the Y-axis direction, and as a result, the connection point 5
There is a difference between the outputs from a and 5b. Therefore, if the difference between the outputs is obtained by the differential amplifier 8, it is possible to separate and detect the voltage associated with the generation of the Coriolis force. Therefore, the output of the differential amplifier 8 is detected by the synchronous detector 9. After that, an angular velocity detection signal can be obtained by smoothing with a smoothing circuit.

[0006]

In such a vibrating gyroscope, the vibrator 3 can vibrate in the X-axis direction and the Y-axis direction via the supporting strips 10a and 10b as shown in FIG. It is supported by the support base 11. Here, the connecting portions 12a and 12b of the vibrator 3 and the supporting strips 10a and 10b are connected to each other with a small area that does not restrain the vibration of the vibrator 3 and are connected to the piezoelectric elements 2a and 2b. Similarly, the lead wires 13a and 13b are also made of fine strips that do not restrain the vibration of the vibrator 3. For this reason, the connecting portions 12a and 12b may be disengaged or the lead wires 13a and 13b may be broken due to long-term vibration or extremely large impact.
There is a case where both b are cut and a required AC voltage cannot be applied to the piezoelectric elements 2a and 2b.

Here, both when the connecting portion 12b is disengaged and when the lead wires 13a and 13b are both disconnected and a voltage cannot be applied to the piezoelectric elements 2a and 2b, the vibrator 3 is self-excited. I can no longer vibrate,
Since the vibration in the X-axis direction stops, even if the angular velocity is input, it becomes substantially impossible to detect the Coriolis force by the piezoelectric elements 2a and 2b. Therefore, when the conventional vibrating gyro is applied to a navigation system of an automobile or the like, malfunction may occur. The present invention has been made in view of such problems of the prior art, and whether or not the vibration gyro is normally operating can be quickly and accurately diagnosed, and Coriolis force, Consequently, the present invention provides a vibration gyro with a diagnostic function, which can greatly improve the reliability of the detection result of the angular velocity.

[0008]

A vibrating gyro with a diagnostic function of the present invention has at least two piezoelectric elements having a detecting function disposed on the side surface of a vibrating body having a prismatic shape such as a triangular prismatic shape or a quadrangular prismatic shape. As a vibrator, and connect the piezoelectric element and one capacitance element to the output side of the driving device through the respective impedance elements, and connect the respective connection points of the respective piezoelectric elements and impedance elements to each other.
A self-excited vibration system is formed by connecting both the capacitive element and the impedance element directly to the differential amplifier via an adder, and connecting the output side of the differential amplifier to the driving device. In this configuration, the output side of the differential amplifier is also connected to frequency monitoring means for monitoring the excitation frequency of the vibrator.

[0009]

With this vibrating gyroscope, if the connecting portion of the vibrator is disconnected or the lead wire is broken, the X
The voltage generated by each piezoelectric element based on the self-excited vibration in the axial direction disappears, and the voltage generated by the self-excited vibration is not included in the output of the differential amplifier that is fed back to the drive device. Therefore, the self-excited vibration of the vibrator stops. On the other hand, since the signals that have passed through the respective impedance elements are all input to the differential amplifier, the differential amplifier electrically operates at a frequency determined by the mutual relationship between the respective impedance elements and one capacitive element. It will oscillate. Since such an electric oscillation frequency is largely different from the excitation frequency of the oscillator in a normal state, the excitation frequency of the oscillator, in other words, the presence or absence of the oscillation frequency is connected to the differential amplifier. By monitoring by the frequency monitoring means
Whether or not the vibration gyro is operated can be accurately and quickly diagnosed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention, in which the same components as those described in the prior art are designated by the same reference numerals. That is, reference numeral 1 in the drawing denotes a quadrangular prism-shaped vibrating body, and 2a and 2b denote piezoelectric elements having a detection function, respectively, which are attached to different side surfaces 1a and 1b of each vibrating body 1, respectively. Reference numeral 3 denotes a vibrator including the vibrating body 1 and the piezoelectric elements 2a and 2b. Reference numeral 4 denotes a driving device, and the output terminals of the driving device 4 are impedance elements Z ₁ , Z ₂ and Z, respectively.
_The piezoelectric elements 2a and 2b and the capacitive element C are connected via the element ₃ . Here, the connection points 5a, 5 of the respective piezoelectric elements 2a, 2b and the impedance elements Z ₁ , Z ₂ are connected.
b is connected to the input terminal of the adder 6, and the output terminal of the adder 6 and the connection point 5c of the impedance element Z ₃ and the capacitive element C are connected to the input terminal of the differential amplifier 7. Further, by connecting the output terminal of the differential amplifier 7 to the driving device 4, a self-excited vibration system of the vibrator 3 is formed.

On the other hand, the connection points 5a, 5 of the piezoelectric elements 2a, 2b and the impedance elements Z ₁ , Z ₂ respectively.
b is also connected to the input terminal of another differential amplifier 8, and the differential amplifier 8 is further connected to the input terminal of the synchronous detector 9 to form a detection system. Here, the synchronous detector 9 is also connected to the drive device 4.

Further, in the illustrated example, the output terminal of the differential amplifier 7 is also connected to the frequency monitoring means 14, and this frequency monitoring means 14 determines whether or not the output frequency from the differential amplifier 8 is within a predetermined range. If it can be detected. by the way,
As the frequency monitoring means 14, for example, as shown in FIG. 2, an FV converter composed of a monostable multivibrator 15 and an average value circuit 16 can be used. In this case, the input frequency is a monostable multivibrator. The vibrator 15 converts the duty cycle, and the average value circuit 16 converts the duty cycle.
Is converted into a voltage according to, and it is determined whether the voltage level at that time is within a predetermined range.

In the vibrating gyroscope having the above-described structure, when the vibrating gyro is normally operated, the vibrator 3 is operated under the action of the self-excited vibrating system in the same manner as described in the prior art. The system can be self-oscillated in the X-axis direction with sufficient stability, and the rotation about the Z-axis is generated under the action of the detection system. Similarly, each connection point 5a, 5b
The difference in the output from the differential amplifier 8 is obtained by the differential amplifier 8, the voltage associated with the generation of the Coriolis force is separated, and the output of the differential amplifier 8 is detected by the synchronous detector 9 and then smoothed by the smoothing circuit. Thus, the angular velocity detection signal can be obtained. As described above, when the vibration gyro is in a normal operating state, the output frequency from the differential amplifier 7 is within the predetermined range, so that the voltage level output from the frequency monitoring means 14 is within the predetermined range. Fits.

On the other hand, as described with reference to FIG.
The connecting portion 12b of the vibrator 3 is disconnected, the lead wire 13a,
If both 13b are disconnected, the oscillator 3
It becomes impossible to perform self-excited vibration in the axial direction, and the voltage generated from the piezoelectric elements 2a and 2b based on the self-excited vibration disappears. For this reason, the voltage based on the self-excited vibration in the X-axis direction is not included in the output of the differential amplifier 7 which is fed back to the drive device 4, and the self-excited vibration of the vibrator 3 is stopped. . In this case, since the signal that has passed through the impedance elements Z ₁ and Z ₂ and the signal from the connection point 5c are input to the differential amplifier 7, the differential amplifier 7
Are electrically oscillated at a frequency determined by the mutual relation of the impedance elements Z ₁ , Z ₂ , Z ₃ and the capacitive element C, and the oscillation frequency at this time is
It is far from the excitation frequency of the vibrator 3 in the normal state. Therefore, by monitoring the excitation frequency of the vibrator 3 by the frequency monitoring means 14, it is possible to accurately and quickly diagnose whether or not the operation of the vibration gyro is correct.

[0015]

As is apparent from the above description, according to the present invention, the output based on self-excited vibration of at least two piezoelectric elements having a detection function is monitored by the excitation frequency of the vibrator. The abnormal self-excited vibration can be detected accurately and quickly.
Appropriateness of the operation of the vibration gyro can be appropriately diagnosed, and the reliability of the detection result of the angular velocity can be greatly improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a configuration example of frequency monitoring means.

FIG. 3 is a diagram showing a conventional example.

FIG. 4 is a view showing a support mechanism of a vibrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibrating body 1a, 1b Side surface 2a, 2b Piezoelectric element 3 Oscillator 4 Driving device 5a, 5b, 5c Connection point 6 Adder 7,8 Differential amplifier 9 Synchronous detector 10a, 10b Supporting strip 11 Supporting base 12a, 12b Connection part 13a, 13b Lead wire 14 Frequency monitoring means

Claims (1)

(57) [Claims] 1. A vibrator having at least two piezoelectric elements having a detection function disposed on the side surface of a prismatic vibrating body, and these piezoelectric elements are provided on the output side of a driving device via respective impedance elements. The output side of the drive device is also connected to the capacitive element via another impedance element, and the respective connection points of the respective piezoelectric elements and impedance elements are connected via an adder,
Where the connection point of the other impedance element and the capacitive element is directly connected together to a differential amplifier, and the output side of this differential amplifier is connected to the drive unit to configure an automatic vibration system, A vibration gyro with a diagnostic function, characterized in that the output side of the differential amplifier is also connected to frequency monitoring means for monitoring the excitation frequency of the vibrator.