CN102519486B - Method for evaluating threshold of fiber optic gyro - Google Patents

Abstract

The invention discloses a method for evaluating the threshold of a fiber optic gyro. The fiber optic gyro is arranged in a single-shaft position turntable with a north reference to make the input shaft of the turntable be in parallel with the horizontal plane, a test position is determined according to a threshold index to be tested and the local latitude, the position turntable is rotated to the test position, calculation is carried out after acquiring multiple fiber optic gyro datum groups, and whether the threshold of the fiber optic gyro satisfies requirements of the index to be tested is evaluated. The method has the advantages of simple operation, easy realization, and guarantee of the test correctness and the test precision.

Description

A kind of method for evaluating threshold of fiber optic gyro

Technical field

The present invention relates to navigation, guidance and control field, relate in particular to a kind of method for evaluating threshold of fiber optic gyro.

Background technology

The threshold value of optical fibre gyro refers to the minimum input angle speed that optical fibre gyro can be responsive, and the output quantity being produced by this input angle speed at least should equal by 50% of the desired output valve of constant multiplier.

Threshold value reflected optical fibre gyro can be responsive minimum input angle speed,, due to the existence of threshold value, optical fibre gyro cannot be responsive to some small angular speed input, caused the measuring error of optical fibre gyro.If threshold value is larger, the measuring error being caused by threshold value has exceeded noise error and drift error, and the static accuracy of optical fibre gyro just cannot have been weighed with conventional indexs such as zero bias stability.For example, suppose by noise and the error that comprehensively causes of drift be 0.1 degree/hour, threshold value be 1 degree/hour, input angle speed be greater than 1 degree/hour time, the measuring error of optical fibre gyro be less than 0.1 degree/hour, but input angle speed be less than 1 degree/hour time, measuring error just much larger than 0.1 degree/hour.

The threshold testing method of multiple optical fibre gyro has been proposed in " GJB2426A-2004 method for testing optical fiber gyroscope " and " GJB2426-95 method for testing optical fiber gyroscope ", as the rate table method of can inclining, panoramic table method, dividing head method and rate table method etc., but these methods all exist defect, be not suitable for threshold of fiber optic gyro test and use.First, use current rate table that the angular speed input of threshold of fiber optic gyro magnitude (0.0001 degree/second) cannot be provided, secondly, each method has all been ignored the inclined to one side concept of optical fibre gyro zero, use zero fixing inclined to one side numerical value, consider that noise during optical fibre gyro zero partially and the magnitude of drift and threshold value are suitable, partially calculate and will inevitably bring larger error with one fixing zero.

Domestic each research institute does not all have very strict test and evaluation method for the threshold value of optical fibre gyro, external yet not relevant open source literature at present.But threshold value has reflected the reliability of optical fibre gyro measuring accuracy, be necessary very much to evaluate and test accurately.We have invented a kind of effective method for evaluating threshold of fiber optic gyro for this reason.

Summary of the invention

The object of the invention is for the deficiencies in the prior art, a kind of method for evaluating threshold of fiber optic gyro is provided.

Object of the present invention is achieved through the following technical solutions:

A kind of method for evaluating threshold of fiber optic gyro, the method comprises turntable test and data processing two parts, the turntable that the method is used is the single shaft position turntable with north orientation benchmark; Wherein, the concrete steps of turntable test portion are as follows:

(1) optical fibre gyro is installed in the single shaft position turntable with north orientation benchmark by frock, and makes optical fibre gyro input shaft parallel with surface level.Now, the angular speed theoretical value Ω on optical fibre gyro input shaft and theoretical output valve F are respectively:

Ω=Ω _e·cosΨ·cosθ

F=K(D ₀+Ω _e·cosΨ·cosθ)

In formula, K is gyro constant multiplier, D ₀for optical fibre gyro zero inclined to one side, Ω _efor earth rotation angular speed, desirable 15.0411 degree/hour, Ψ is test point geographic latitude, θ be optical fibre gyro input shaft and geographic north to angle;

(2) according to threshold of fiber optic gyro Ω to be measured, by:

$\mathrm{\θ}={\cos }^{-1}\left(\frac{\mathrm{\Ω}}{{\mathrm{\Ω}}_e\cos \mathrm{\ψ}}\right)$

Determine the position while test, calculate the numerical value of the angle theta of this test position optical fibre gyro input shaft and north orientation, be designated as θ ₁;

(3) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁position on, test t optical fibre gyro second output valve is also averaged, and is designated as F ₁₁, test duration t is determined by the precision of testing fiber gyro, specifically obtains by Allan variance analysis method.

(4) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁on the position of+π, test t optical fibre gyro second output valve is also averaged, and is designated as F ₂₁.

(5) repeating step (3) and step (4), carries out N two positions test altogether, and N is generally the natural number that is greater than 5, obtains optical fibre gyro output data F _1jand F _2j(j=1-N).In each test, the theoretical output valve of the optical fibre gyro angular speed of two positions is respectively:

F _1j=K(D ₀+Ω _e·cosΨ·cosθ ₁)

F _2j=K(D ₀+Ω _e·cosΨ·cos(θ ₁+π))

After turntable off-test, collect altogether N group data of optical fiber gyroscope and process, for passing judgment on the whether satisfied judging quota for the treatment of of threshold value of optical fibre gyro,

Described data processing section concrete steps are as follows:

(1) calculate the optical fibre gyro angular rate measurement value ω that N group is tested _j(j=1-N);

${\mathrm{\ω}}_j=\frac{F_{1j}-F_{2j}}{2K}$

(2) for N result of calculation ω _j(j=1-N), abandon two maximal values and two minimum value, remaining test value is averaged as the measured value ω of angular speed;

(3) numerical value of computation and measurement error delta:

$\mathrm{\δ}=\left|\frac{\mathrm{\ω}-\mathrm{\Ω}}{\mathrm{\Ω}}\right|$

When δ drops in [0.5,1.5] interval, think that the threshold value of tested optical fiber gyro is better than treating judge value, treat judge value otherwise think that the threshold value of tested optical fiber gyro is inferior to.

The invention has the beneficial effects as follows:

1, simple to operate, testing procedure is clear and definite, and the test duration is short, and total testing time is no more than 30 minutes;

2, data processing method has been eliminated zero inclined to one side impact,, containing approximate error, has not guaranteed the precision of test value and the correctness of test result.

3, propose first feasible method for evaluating threshold of fiber optic gyro, filled up the blank of measuring technology.

Embodiment

The principle of threshold testing is to manage to make optical fibre gyro to be in input angle speed very under circlet border, tests its output and compares with theoretical value.Near optical fibre gyro input shaft points to geographical East and West direction time, the angular speed on optical fibre gyro input shaft is very little, by the measurement to these little angular speeds, can pass judgment on the threshold property of optical fibre gyro.Therefore, as long as select suitable position, the theoretical input angle speed of this position is identical with threshold value to be measured, just can realize threshold value evaluation and test.

Will accurately obtain the angular rate measurement value of optical fibre gyro under certain test position, must remove the inclined to one side impact of optical fibre gyro zero, can adopt two positions method of testing for this reason,, on two test positions, the difference of the numerical value of optical fibre gyro and north orientation angle is 180 degree.Further, because zero of optical fibre gyro contains random and drift error in partially, use the angular rate measurement value of two positions method gained still to comprise error.Therefore first in the time of each position measurement, will select the suitable test duration, this can be drawn by the Allan variance analysis method of optical fibre gyro, secondly also will increase the number of times of test and abandon exceptional value to increase the confidence level of test value.

Further, 50% criterion in threshold of fiber optic gyro definition is also unreasonable, in the time that the magnitude of optical fibre gyro zero bias stability approaches or is greater than tested angular speed magnitude, test value can not reflect measured value, for example for 0.01 degree/hour angular speed input, as the precision of optical fibre gyro be 0.1 degree/hour, actual test value can not be less than 0.005 degree/hour certain numerical value.Therefore actual criterion can not be unidirectional, must be an interval.Consider the symmetry of error, it is rational criterion being made as to [0.5,1.5].The meaning of threshold value is just clearer and more definite like this, and threshold value is the minimum input angle speed of optical fibre gyro institute energy Measurement accuracy, and so-called Measurement accuracy refers to that measuring error is no more than measured 50%.

Describe the present invention in detail according to above-mentioned evaluation and test principle below, it is more obvious that object of the present invention and effect will become.

This method of testing is divided into turntable test and data processing two parts.The turntable that this method is used is the single shaft position turntable with north orientation benchmark.

The concrete steps of turntable test are as follows:

(1) optical fibre gyro is installed in the single shaft position turntable with north orientation benchmark by frock, and makes optical fibre gyro input shaft parallel with surface level.Now, the angular speed theoretical value Ω on optical fibre gyro input shaft and theoretical output valve F are respectively:

Ω=Ω _e·cosΨ·cosθ （1）

F=K(D ₀+Ω _e·cosΨ·cosθ)

In formula, K is gyro constant multiplier, D ₀for optical fibre gyro zero inclined to one side, Ω _efor earth rotation angular speed, desirable 15.0411 degree/hour, Ψ is test point geographic latitude, θ be optical fibre gyro input shaft and geographic north to angle;

(2) according to threshold of fiber optic gyro Ω to be measured, by

$\mathrm{\θ}={\cos }^{-1}\left(\frac{\mathrm{\Ω}}{{\mathrm{\Ω}}_e\cos \mathrm{\ψ}}\right)---\left(2\right)$

Determine the position while test, calculate the numerical value of the angle theta of this test position optical fibre gyro input shaft and north orientation, be designated as θ ₁;

(3) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁position on, test t optical fibre gyro second output valve is also averaged, and is designated as F ₁₁, test duration t is determined by the precision of testing fiber gyro, specifically obtains by Allan variance analysis method.

(4) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁on the position of+π, test t optical fibre gyro second output valve is also averaged, and is designated as F ₂₁.

(5) repeating step (3) and step (4), carries out the test of several times (general more than 5 times, to be 10 times in the present embodiment) two positions altogether, obtains optical fibre gyro output data F _1jand F _2j(j=1-10).In each test, the theoretical output valve of the optical fibre gyro angular speed of two positions is respectively:

F _1j=K(D ₀+Ω _e·cosΨ·cosθ ₁) （3）

F _2j=K(D ₀+Ω _e·cosΨ·cos(θ ₁+π))

After turntable off-test, collect altogether 10 groups totally 20 data of optical fiber gyroscopes process, whether the threshold value of passing judgment on optical fibre gyro meets and treats judging quota.

Data processing section concrete steps are as follows:

(1) calculate 10 groups of optical fibre gyro angular rate measurement value ω that test _j(j=1-10);

${\mathrm{\ω}}_j=\frac{F_{1j}-F_{2j}}{2K}---\left(4\right)$

(2) for 10 result of calculation ω _j(j=1-10), abandon two maximal values and two minimum value, average as the measured value ω of angular speed to remaining 6 test values;

(3) numerical value of computation and measurement error delta:

$\mathrm{\δ}=\left|\frac{\mathrm{\ω}-\mathrm{\Ω}}{\mathrm{\Ω}}\right|---\left(5\right)$

In the time that δ is less than 0.5, thinks that the threshold value of optical fibre gyro is greater than Ω, otherwise think that the threshold value of optical fibre gyro is less than Ω.The threshold value of measuring fiber gyro as accurate in need, can reduce Ω gradually, until δ is less than 0.5.And actual in the performance evaluating of optical fibre gyro, threshold value is a judging quota rather than a test index, and whether the threshold value that only need obtain tested optical fiber gyro is better than treating the conclusion of judging quota, and without testing out threshold value accurately.Therefore, as long as select test position according to judging quota, test value differentiated: when δ drops in [0.5,1.5] interval, think that the threshold value of tested optical fiber gyro is better than (being less than) and treats judge value, otherwise think that the threshold value of tested optical fiber gyro is inferior to (being greater than) and treats judge value.

Claims (1)

1. a method for evaluating threshold of fiber optic gyro, is characterized in that, the method comprises turntable test and data processing two parts, and the turntable that the method is used is the single shaft position turntable with north orientation benchmark; Wherein, the concrete steps of turntable test portion are as follows:

(1) optical fibre gyro is installed in the single shaft position turntable with north orientation benchmark by frock, and makes optical fibre gyro input shaft parallel with surface level; Now, the angular speed theoretical value Ω on optical fibre gyro input shaft and theoretical output valve F are respectively:

Ω=Ω _e·cosΨ·cosθ

F=K(D ₀+Ω _e·cosΨ·cosθ)

In formula, K is gyro constant multiplier, D ₀for optical fibre gyro zero inclined to one side, Ω _efor earth rotation angular speed, get 15.0411 degree/hour, Ψ is test point geographic latitude, θ be optical fibre gyro input shaft and geographic north to angle;

(2) according to threshold of fiber optic gyro Ω to be measured, by:

$\mathrm{\θ}={\cos }^{-1}\left(\frac{\mathrm{\Ω}}{{\mathrm{\Ω}}_e\cos \mathrm{\ψ}}\right)$

Determine the position while test, calculate the numerical value of the angle theta of this test position optical fibre gyro input shaft and north orientation, be designated as θ ₁;

(3) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁position on, test t optical fibre gyro second output valve is also averaged, and is designated as F ₁₁, test duration t is determined by the precision of testing fiber gyro, specifically obtains by Allan variance analysis method;

(4) angle that position turntable is turned to optical fibre gyro input shaft and north orientation is θ ₁on the position of+π, test t optical fibre gyro second output valve is also averaged, and is designated as F ₂₁;

(5) repeating step (3) and step (4), carries out N two positions test altogether, and N is greater than 5 natural number, obtains optical fibre gyro output data F _1jand F _2j(j=1-N); In each test, the theoretical output valve of the optical fibre gyro angular speed of two positions is respectively:

F _1j=K(D ₀+Ω _e·cosΨ·cosθ ₁)

F _2j=K(D ₀+Ω _e·cosΨ·cos(θ ₁+π))

After turntable off-test, collect altogether N group data of optical fiber gyroscope and process, for passing judgment on the whether satisfied judging quota for the treatment of of threshold value of optical fibre gyro,

Described data processing section concrete steps are as follows:

(1) calculate the optical fibre gyro angular rate measurement value ω that N group is tested _j(j=1-N);

${\mathrm{\ω}}_j=\frac{F_{1j}-F_{2j}}{2K}$

(2) for N result of calculation ω _j(j=1-N), abandon two maximal values and two minimum value, remaining test value is averaged as the measured value ω of angular speed;

(3) numerical value of computation and measurement error delta:

$\mathrm{\δ}=\left|\frac{\mathrm{\ω}-\mathrm{\Ω}}{\mathrm{\Ω}}\right|$

When δ drops in [0.5,1.5] interval, think that the threshold value of tested optical fiber gyro is better than treating judge value, treat judge value otherwise think that the threshold value of tested optical fiber gyro is inferior to.