JP3292002B2 - Angular velocity sensor and method for correcting null voltage of angular velocity sensor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor and a method of correcting null voltage of the angular velocity sensor using the same, and more particularly, for example, an angular velocity sensor used in a navigation system or a camera shake correction system of a video recorder and an angular velocity using the same The present invention relates to a sensor null voltage correction method.

[0002]

2. Description of the Related Art For example, in an angular velocity sensor using vibration of a vibrating body, a constant offset voltage is set.
Then, the output voltage of the angular velocity sensor is measured with reference to the offset voltage, and the magnitude and direction of the applied rotational angular velocity are detected. However, the angular velocity sensor has a temperature characteristic, and the null voltage when the rotational angular velocity is not applied may deviate from the set offset voltage due to a temperature change. Conventionally, as shown in FIG. 7 , upper and lower limits of a null voltage are determined,
Angular velocity sensors within the range are regarded as good products, and angular velocity sensors outside the range are regarded as defective products.

As a method of correcting a null voltage of an angular velocity sensor, there is a method of using a thermistor, a method of storing temperature characteristics in a ROM, and correcting the temperature characteristics. If these methods are used, a substantially constant null voltage can be output even when the temperature changes.

[0004]

However, in the above-mentioned method, other components such as a thermistor and a ROM are required, and the number of components required for the angular velocity sensor increases. In the method using a thermistor, it is necessary to use a thermistor having different characteristics according to the temperature characteristics of the null voltage. Therefore, when manufacturing the angular velocity sensor, a thermistor suitable for each angular velocity sensor must be selected, and the number of steps increases. Further, in the method using the ROM, if the temperature setting step for correction is rough, the correction is performed at once near the boundary of the set temperature, and the null voltage changes zigzag due to the temperature change.

Therefore, a main object of the present invention is to provide an angular velocity sensor capable of grasping the temperature characteristics of individual null voltages, and a null velocity sensor capable of correcting the null voltage by using the obtained temperature characteristics. It is to provide a voltage correction method.

[0006]

According to the present invention, a temperature characteristic of a null voltage when a rotational angular velocity is not applied is expressed by a linear expression.
A linear approximation is performed, and the voltage corresponding to the slope of the
And added to the output, the sensor output at the time of no rotation at a reference temperature
With respect to a predetermined known reference voltage
The voltage should be shifted by the voltage corresponding to the slope of the approximate straight line.
To correct the null voltage of the sensor.
Sensor output can extract gradient information of voltage to temperature.
It is an angular velocity sensor superimposed on a force . Further, the method according to the present invention provides a method for controlling the angular velocity sensor at the reference voltage.
Measuring the output voltage during rotation; and
To compare with a known, predetermined reference voltage
From the above, the step of analyzing the temperature characteristics of a linear approximation of the null voltage of the angular velocity sensor, the step of measuring the temperature,
Calculating a null voltage correction value from the analyzed temperature characteristic of the null voltage of the angular velocity sensor and the measured temperature; and correcting the null voltage of the angular velocity sensor by the null voltage correction value. This is a voltage correction method.

[0007] The primary temperature characteristics of the null voltage of the angular velocity sensor
The voltage corresponding to the slope of the approximation straight line
The sensor output during non-rotation is
The slope of the approximate straight line with respect to a predetermined reference voltage
Is configured to shift by the voltage corresponding to
By comparing with a known reference voltage, the null voltage
The temperature characteristics approximated by a straight line can be analyzed. If the temperature characteristic of the null voltage of the angular velocity sensor is known, a correction value at that temperature can be obtained by measuring the temperature. The null voltage of the angular velocity sensor is corrected by the obtained correction value.

[0008]

According to the present invention, the temperature characteristics of the null voltage of each angular velocity sensor can be easily known. Therefore, by measuring the temperature, a correction value at that temperature is obtained, and the null voltage of the angular velocity sensor is corrected. Thus, when the angular velocity sensor is used, the fluctuation of the null voltage with respect to the temperature change can be suppressed. Therefore, the rotational angular velocity can be accurately detected.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an angular velocity sensor utilizing vibration of a vibrating body will be described. FIG. 1 is an illustrative view showing one example of an angular velocity sensor of the present invention. The angular velocity sensor 10 includes a vibration gyro 12. Vibrating gyroscope 12
As shown in FIGS. 2 and 3, for example, includes a regular triangular prism-shaped vibrating body 14. The material of the vibrating body 14 is generally formed of a material that generates mechanical vibration, such as an elinvar, an iron-nickel alloy, quartz, glass, quartz, or ceramic.

The piezoelectric element 1 is provided on three sides of the vibrating body 14.
6a, 16b and 16c are formed. Piezoelectric element 16a
Is a piezoelectric layer 1 formed of, for example, a piezoelectric ceramic.
8a. The electrodes 2 are provided on both sides of the piezoelectric layer 18a.
0a and 22a are formed. Then, one electrode 22a
Is adhered to the vibrating body 14. Similarly, the piezoelectric element 16
b, 16c include piezoelectric layers 18b, 18c,
b, 18c, electrodes 20b, 22b and electrode 2
0c and 22c are formed. Then, the piezoelectric elements 16b,
One electrode 22b, 22c of 16c is adhered to the vibrating body 14.

The resistors 24a and 24b are connected to the piezoelectric elements 16a and 16b, respectively. These resistors 24a,
An oscillation circuit 26 is connected between 24b and the piezoelectric element 16c. Further, the piezoelectric elements 16a and 16b are connected to a differential circuit 28. The differential circuit 28 is connected to a synchronous detection circuit 30, and the synchronous detection circuit 30 is connected to a DC amplifier 32. This DC amplifier 32 is connected to an offset voltage adjuster 34. Note that the offset voltage adjuster 3
4 may be connected before the DC amplifier 32. The offset voltage adjuster 34 may be any device having a function of adjusting the final DC output.

In the vibrating gyroscope 12, the piezoelectric elements 16a,
16b is used for driving to vibrate the vibrating body 14 and for detecting for obtaining a signal corresponding to the rotational angular velocity. Further, another piezoelectric element 16c is used for feedback for driving the vibrating body 14 by self-excited vibration. That is, the piezoelectric element 1
A drive signal is given to 6a and 16b, and an output signal of the piezoelectric element 16c is fed back to the oscillation circuit 26. By this drive signal, the vibrating body 14 bends and vibrates in a direction orthogonal to the surface on which the piezoelectric element 16c is formed.

At the time of non-rotation, the piezoelectric elements 16a, 1
6b are the same, and no signal is output from the differential circuit 28. When rotated about the axis of the vibrating body 14, the direction of vibration of the vibrating body 14 changes due to Coriolis force. As a result, a difference occurs between the output signals of the piezoelectric elements 16a and 16b, and a signal corresponding to the change in the vibration direction, that is, a signal corresponding to the Coriolis force, is output from the differential circuit 28. Therefore, the output signal of the differential circuit 28 is a signal corresponding to the added rotational angular velocity.

The output signal of the differential circuit 28 is detected by a synchronous detection circuit 30. The detected signal is amplified by the DC amplifier 32. Then, the offset voltage adjuster 34
Sets the offset voltage. Usually, the offset voltage is set so as to be のof the drive voltage as a reference voltage . For example, when the drive voltage is 5V, the offset voltage is set to 2.5V. That is, normal temperature (25 ° C)
Is adjusted by the offset voltage adjuster 34 so that the null voltage of the angular velocity sensor 10 becomes 2.5V.

However, the angular velocity sensor 1 of the present invention
At 0, the temperature characteristics of the null voltage are measured first. That is, while the rotational angular velocity is not applied, the ambient temperature is changed, and the change in the output voltage of the angular velocity sensor 10 is measured. Then, as shown in FIG. 4, the slope of the temperature characteristic of the null voltage is analyzed from the output voltage of the angular velocity sensor 10 by, for example, the least square method. The offset voltage is set by the offset voltage adjuster 34 in accordance with the obtained gradient of the temperature characteristic. For example, when the slope of the temperature characteristic of the null voltage is 200 mV / 100 ° C., the offset voltage is set to 2.7 V higher than the normal offset voltage (reference voltage) by 0.2 V. If the slope of the temperature characteristic of the null voltage is −100 mV / 100 ° C., the offset voltage is set to 2.4 V by lowering the offset voltage (reference voltage) by 0.1 V. Thus, the offset voltage corresponding to the temperature characteristic of the null voltage is set for each angular velocity sensor 10.

When this angular velocity sensor 10 is incorporated in a device, as shown in FIG. 5 , an output signal of the angular velocity sensor 10 is passed through an A / D converter 36 to the arithmetic unit 3 in the device.
8 is input. In the arithmetic unit 38, as shown in FIG.
To, from the output signal of the angular velocity sensor 10 at the time of no rotation at room temperature, the offset voltage is measured. This offset voltage is stored in a ROM or the like. Then, the slope of the temperature characteristic of the null voltage is obtained from the stored offset voltage. Further, the ambient temperature is measured by the temperature sensor. Next, from the measured temperature and the slope of the temperature characteristic,
A correction value at the temperature at that time is calculated. That is,
Assuming that the normal temperature (25 ° C.) is the reference temperature T ₀ and the inclination of the temperature characteristic is α, the correction value V of the null voltage at the temperature T _X
Is determined by V = α (T _X −T ₀ ). Therefore,
If the difference between the output voltage of the angular velocity sensor 10 and the correction value V is calculated, the angular velocity sensor 10
Can be kept almost constant. As described above, if the null voltage is corrected using the angular velocity sensor 10, drift due to a temperature change can be suppressed, and the rotational angular velocity can be accurately detected.

[0018] In the angular velocity sensor 10 of the present invention, corresponding to the inclination of the temperature characteristic of the null voltage, since the to output a correction signal to adjust the offset voltage, when using the angular velocity sensor 10, the null The voltage can be corrected. For this reason, an angular velocity sensor that has been defective in the past can be used, and the rotational angular velocity can be detected with a very small error.

Although the vibrating gyroscope 12 is used for the angular velocity sensor 10 described above, even when an angular velocity detecting element other than the vibration type is used, the offset voltage is adjusted according to the temperature characteristics of the null voltage. Or, by outputting the correction signal, all the angular velocity sensors can be used as non-defective products. Moreover, even when an angular velocity sensor having a temperature characteristic of a null voltage is used, the rotational angular velocity can be accurately detected by correcting the angular velocity sensor.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one example of an angular velocity sensor of the present invention;

FIG. 2 is a perspective view of a vibrating gyroscope used in the angular velocity sensor shown in FIG.

FIG. 3 is a sectional view of the vibrating gyroscope shown in FIG. 2;

FIG. 4 is a graph showing a change in a null voltage of an angular velocity sensor with respect to a temperature change, and a slope of a temperature characteristic obtained from the relationship between the change in the null voltage.

FIG. 5 is an illustrative view showing a case where the angular velocity sensor shown in FIG. 1 is incorporated in a device;

6 is a flowchart showing a case where a null voltage is corrected using the angular velocity sensor shown in FIG.

FIG. 7 is a graph showing the relationship between a good product and a bad product in temperature characteristics of a conventional angular velocity sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Angular velocity sensor 12 Vibration gyroscope 26 Oscillation circuit 28 Differential circuit 30 Synchronous detection circuit 32 DC amplifier 34 Offset voltage regulator 36 A / D converter 38 Arithmetic unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-167342 (JP, A) JP-A-4-152210 (JP, A) JP-A-3-162616 (JP, A) 33022 (JP, U) Kunio Tada (eds.), Sensor Technology, Japan, Maruzen Co., Ltd., September 10, 1991, 207-222 (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19 / 56 G01P 9/04

Claims (2)

(57) [Claims] 1. A linear approximation of a temperature characteristic of a null voltage when a rotational angular velocity is not applied by a linear expression, and a slope of the approximate straight line.
The corresponding voltage is added to the sensor output to
Sensor output during non-rotation
Corresponds to the slope of the approximate straight line with respect to a known reference voltage
By configuring to shift by the voltage,
Information on the slope of the null voltage with respect to temperature
An angular velocity sensor that superimposes information on the sensor output in an extractable manner . 2. The reference voltage of the angular velocity sensor according to claim 1,
Measuring the output voltage at the time of non-rotation , the output voltage and a predetermined known reference voltage
By comparing, the null voltage of the angular velocity sensor ,
Analyzing a linearly approximated temperature characteristic; measuring a temperature; obtaining a null voltage correction value from the analyzed temperature characteristic of the null voltage of the angular velocity sensor and the measured temperature;
And a step of correcting the null voltage of the angular velocity sensor based on the correction value of the null voltage.