JP2518103B2 - Optical fiber gyro and its angular velocity detection and adjustment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical fiber gyro, an angular velocity detection method for the optical fiber gyro, and an optical fiber gyro adjustment method.

[Prior Art] FIG. 3 shows a configuration of a conventional optical fiber gyro (hereinafter abbreviated as OFG).

The OFG is a light source 11 such as a laser, an optical fiber 12 that is multi-wound, a coupler 13 that couples and separates light, an output signal detector 14 that includes a photodiode, and a processing circuit 15 that processes the output signal. It is composed of

OFG uses a relativistic effect called the Sagnac effect. This effect is due to the difference in the propagation times of two lights propagating in the opposite directions in the optical path of the optical fiber 12 which is separated by the coupler 13 and is multi-wound.
That is, it is a phenomenon in which the phase difference changes in proportion to the angular velocity of rotation of the optical fiber 12. If the optical fiber 12 is not rotating, the phase difference Δφ between the two lights coupled by the coupler 13 after traveling in the opposite direction on the optical path is zero.

In an actual OFG, a signal of an optical output value of a synthetic wave formed by coupling two lights traveling in opposite directions is detected. The angular velocity Ω is detected by utilizing the fact that this output signal is proportional to the constant component and cos (Δφ).

 The relationship between the phase difference Δφ and the angular velocity Ω is shown by the following equation.

Here, λ: wavelength, С: speed of light, А: loop area of optical fiber.

At low angular velocities, cos (Δφ) changes only slightly because Δφ is small. Therefore, conventionally, a phase shift is used to increase the measurement sensitivity, and the newly measured phase difference Δφ ′ is set to Δφ ′ = Δφ ′ + π / 2. That is, by setting cos (Δφ ′) = cos (Δφ + π / 2) = sin (Δφ), the output signal is made proportional to sin (Δφ), and the sensitivity to low angular velocity is improved.

Further, the adjustment of OFG is performed by adjusting the unadjusted OFG42 as shown in FIG.
Is fixed on the turntable 41, while the turntable controller 43 controls the rotation angular velocity of the turntable 41 with high accuracy, the angular velocity detection signal of the unadjusted OFG 42 and the signal of the turntable controller 43 are compared by the computer 25, The unadjusted OFG 42 is adjusted so that its detected angular velocity matches the actual angular velocity (that is, the rotational angular velocity of the turntable 41 of the controller 43).

[Problems to be Solved by the Invention] As described above, in the conventional OFG, since the angular velocity is derived based on the change in the output signal caused by the phase difference between the two lights, a complicated calculation process including a trigonometric function is performed. is necessary. Therefore, it takes about 0.1 seconds / data to calculate the angular velocity, which is difficult to apply to an airplane, a rocket, or the like that requires high-speed response.

In addition, it is necessary to prepare a highly accurate turntable when adjusting the OFG, and it is difficult to easily perform maintenance at the site where the OFG is used.

An object of the present invention is to solve the above problems and an OFG and its angular velocity detection method capable of significantly improving responsiveness,
Another object of the present invention is to provide an OFG adjustment method that can facilitate maintenance.

[Means for Solving the Problems] In order to achieve the above object, in the OFG of the present invention,
In the area where the slope of the curve of the signal output value is large, the correlation data between the input angular velocity and the signal output value is stored with a small data interval of the input angular velocity, and the data in the memory and the optical fiber gyro are stored. An arithmetic processing unit for detecting the angular velocity by comparing it with a signal output value corresponding to the actually input angular velocity.

Next, in the angular velocity detection method for OFG according to the present invention, the correlation data between the input angular velocity and the signal output value is set to the OFG, and the data interval of the input angular velocity is set in the region where the slope of the curve of the signal output value is large. Is stored in advance with a small value, and the angular velocity is detected by comparing this correlation with the signal output value corresponding to the angular velocity subsequently input to the optical fiber gyro.

Further, in the angular velocity detection method, the correlation is stored as data in the memory inside the OFG, and the data in the memory is compared with the signal output value corresponding to the angular velocity subsequently input to this OFG. Then, the angular velocity may be detected.

The data stored in the memory is preferably graph data of the correlation between the input angular velocity and the signal output value obtained by rotating the OFG in advance.

Next, in the adjusting method according to the present invention, the correlation data between the input angular velocity and the signal output value is stored with a small data interval of the input angular velocity in the region where the slope of the curve of the signal output value is large. In an optical fiber gyro equipped with a memory, and an arithmetic processing unit that compares the data in the memory with a signal output value corresponding to the angular velocity actually input to the optical fiber gyro to detect the angular velocity, Prepare an adjusted optical fiber gyro that has been adjusted for detection and an unadjusted optical fiber gyro to be adjusted, rotate both at the same angular velocity at the same time, and adjust the detection angular velocity of the unadjusted optical fiber gyro Adjusted the correlation data stored in the memory of the optical fiber gyro so that it is equal to the detected angular velocity of the optical fiber gyro. It is.

[Operation] FIG. 2 shows the correlation between the input angular velocity when the OFG is rotated by the turntable, that is, the rotational angular velocity of the turntable (horizontal axis) and the output signal of the OFG (vertical axis).

In the present invention, this graph is stored as data in the memory in the OFG processing device. The OFG externally outputs the detected angular velocity (value on the horizontal axis) corresponding to the signal output value (value on the vertical axis) based on the phase difference between the two lights generated by the rotation. The adjustment of OFG in the present invention is nothing but correction of the data stored in the memory.

In this way, by comparing the data stored in the memory with the signal output value in advance and detecting the angular velocity, the complicated comparison for deriving the angular velocity from the signal output value unlike the conventional case is not performed, and the simple comparison is performed. The angular velocity can be accurately obtained only by calculation.

By the way, as is apparent from FIG. 2, the output signal curve has a large inclination at a minute angular velocity. Therefore, by adopting the data of the output signal curve in which the data interval of the input angular velocity is made small as the data to be stored in the memory, the angular velocity detection accuracy in the minute angular velocity region can be remarkably improved. Further, if the data of the output signal curve is stored in the memory at equal intervals of the data of the signal output values, the number of data can be reduced and the small memory area can be used.

Further, when the unadjusted OFG is adjusted, the adjustment signal can be accurately and easily adjusted by using the detection signal of the adjusted OFG that rotates at the same angular velocity as the reference signal at the same time.

Example Next, an example of the present invention will be described.

As shown in FIG. 1, on the turntable 1, an adjusted OFG2 that has already been adjusted and an unadjusted OFG3 that is to be adjusted are both fixed. The outputs of these OFGs 2 and 3 are connected to a computer 5 via a signal line 4. The turntable 1 is configured to be driven by a motor or the like so that the rotational angular velocity can be freely changed from low speed to high speed.

The adjusted and unadjusted OFGs 2 and 3 have a memory for storing the correlation data of the input angular velocity and the signal output value, and the data in the memory and the signal output value corresponding to the angular velocity actually input to the OFG. And an arithmetic processing unit for comparing and detecting the angular velocity. Therefore, adjusting the unadjusted OFG3 is nothing but correcting the correlation data stored in the memory of the unadjusted OFG3 to be equal to the correlation data stored in the memory of the adjusted OFG2.

Therefore, in this embodiment, when the rotational angular velocity of the turntable 1 is increased from low speed to high speed, the adjusted OFG2
The detected angular velocity output from the above and the signal output value output from the unadjusted OFG3 are input to the computer 5 in association with each other,
The computer 5 forms and holds the correlation data corresponding to the graph of FIG. This data is the correlation data between the input angular velocity of unadjusted OFG3 and the signal output value. Therefore, if this correlation data is input to the memory of the unadjusted OFG3, the adjustment of the unadjusted OFG3 is completed.

In this way, the unadjusted OFG3 can be easily and accurately adjusted by using the detected angular velocity of the adjusted OFG2 that rotates at the same angular velocity as the unadjusted OFG3 as the reference angular velocity. Further, this allows the OFG to be adjusted without preparing a highly accurate turntable, and the maintenance can be easily performed at the site where the OFG is used.

According to the OFG adjusted by the above method, the angular velocity can be accurately obtained by comparing the data stored in the memory with the signal output value. Therefore, the calculation processing is greatly simplified as compared with the conventional OFG, and the responsiveness can be significantly improved. As a result, OFG can be applied with sufficient reliability as a gyro for rockets that require a high degree of responsiveness. In addition, due to the simplified arithmetic processing, OFG
Since a low-priced one with a small processing capacity can be used as an internal arithmetic unit, or a part of it can be substituted with a memory,
The price of OFG can be reduced.

In the above embodiment, when adjusting the unadjusted gyro 3,
The adjusted OFG2 and the unadjusted OFG3 are fixed on the turntable 1, but the point is that these two OFGs should be given the same angular velocity at the same time. Therefore, the unadjusted OFG3 may be fixed on the adjusted OFG2 and the adjusted OFG2 may be rotated.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects can be exhibited.

(1) Since the angular velocity can be accurately obtained only by a simple comparison calculation without performing complicated calculation, the responsiveness can be significantly improved.

Particularly, in the present invention, as the correlation data of the input angular velocity and the signal output value, the signal output value data in which the data interval of the input angular velocity is small is adopted in the region where the slope of the curve of the signal output value is large, so that the minute angular velocity The angular velocity detection accuracy in the area can be significantly improved.

(2) Since OFG can be adjusted accurately without using a high-precision turntable, it can be used in the field where OFG is used.
Can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a correlation between an input angular velocity and a signal output value, FIGS. 3 and 4 are diagrams showing a conventional example. In the figure, 2 is an adjusted optical fiber gyro, and 3 is an unadjusted optical fiber gyro.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) The inventor Hisanori Nakai 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hidaka factory, Hiritsu Electric Wire Co., Ltd. (56) References Japanese Patent Laid-Open No. 1-303811 A) JP 61-284622 (JP, A) JP 3-152415 (JP, A) JP 4-106419 (JP, A) JP 61-48714 (JP, A)

Claims (5)

(57) [Claims] 1. A memory in which correlation data between an input angular velocity and a signal output value is stored with a small data interval of the input angular velocity in an area where the slope of the curve of the signal output value is large, and data in the memory. An optical fiber gyro, comprising: an arithmetic processing unit for detecting the angular velocity by comparing the signal output value corresponding to the angular velocity actually input to the optical fiber gyro. 2. Correlation data between an input angular velocity and a signal output value is stored in advance in an optical fiber gyro with a small data interval of the input angular velocity in an area where the slope of the curve of the signal output is large. An angular velocity detecting method for an optical fiber gyro, wherein the angular velocity is detected by comparing the correlation with a signal output value corresponding to the angular velocity subsequently input to the optical fiber gyro. 3. The correlation is stored as data in a memory inside the optical fiber gyro, and the data in the memory is compared with a signal output value corresponding to an angular velocity subsequently input to the optical fiber gyro. The angular velocity detecting method for an optical fiber gyro according to claim 2, wherein the angular velocity is detected. 4. The light according to claim 3, wherein the data stored in the memory is graph data of a correlation between an input angular velocity and a signal output value obtained by previously rotating the optical fiber gyro. Fiber gyro angular velocity detection method. 5. A memory in which correlation data between an input angular velocity and a signal output value is stored with a small data interval of the input angular velocity in a region where the slope of the curve of the signal output value is large, and data in the memory. In the optical fiber gyro, the adjustment for detecting the angular velocity is completed in the optical fiber gyro that includes an arithmetic processing unit that compares the signal output value corresponding to the angular velocity actually input to the optical fiber gyro Prepare an adjusted optical fiber gyro and an unadjusted optical fiber gyro to be adjusted, rotate both at the same angular velocity at the same time, and the detected angular velocity of the unadjusted optical fiber gyro becomes equal to the detected angular velocity of the adjusted optical fiber gyro. The optical fiber gyro is characterized in that the correlation data stored in the memory of the unadjusted optical fiber gyro is adjusted. Method of adjusting the color.