Methods for testing laser gyroscope
1 Scope
1.1 Subject content
This standard specifies the relevant terms of single-axis laser gyroscope (hereinafter referred to as “gyroscope”) and the methods for testing its performance.
1.2 Application scope
This standard is applicable to the performance testing of gyroscopes used on various carriers in the land, sea, air and space fields.
This standard may also serve as a reference for the performance testing of three-axis laser gyroscope.
1.3 Application guide
For the test items listed in this standard, those with the same test equipment and similar test procedures can be tested together as needed, and then their respective test data can be processed with their corresponding calculation methods accordingly.
2 Normative references
GB 321-80 Preferred numbers and preferred number series
GJB 585-88 Inertial technical terms
3 Definitions
Terms not defined in this standard shall be as specified in GJB 585.
3.1
laser gyroscope
device for measuring angular velocity and angle, which is based on sagnac effect and composed of a ring laser resonator, and when it rotates around the vertical line of the equivalent plane of the closed optical path, the resonant frequencies of the two beams transmitted backwards are different, their frequency difference is proportional to the angular velocity of the resonator rotating relative to the inertial space, and the output pulse number is proportional to the rotating angle, so by checking the frequency difference and the pulse number, the angular velocity and rotating angle of the gyroscope can be obtained
3.2
input axis, IA
axis perpendicular to the equivalent plane of the closed optical path, when the gyroscope rotates around this axis, the maximum output will be produced
3.3
input reference axis, IRA
axis perpendicular to the mounting surface of gyroscope, nominally parallel to the input axis
3.4
input axis misalignment, γm
angle between input axis and input reference axis, mrad
3.5
input angular rate, Ω
angular displacement of the gyroscope around the input axis per unit time, also referred to as the input rate, (°)/s
3.6
scale factor, K
ratio of the output to the input of gyroscope, it is proportional to the area of closed loop and inversely proportional to the total length of the optical path and the working wavelength, p/(")
3.7
scale factor nonlinearity, Km
within the range of input angular rate, the ratio of the maximum deviation of gyroscope output to input relative to the scale factor to the scale factor, ppm
3.8
scale factor asymmetry, Ka
within the range of input angular rate, the ratio of the difference of scale factor between the forward and reverse input angular rate of gyroscope and its average value, ppm
3.9
scale factor repeatability, kr
consistency between scale factors of gyroscope when measured repeatedly under the same conditions and at specified intervals, expressed as the ratio of the standard deviation of the scale factors obtained from each test to its average value, ppm, %
3.10
scale factor temperature sensitivity, kt
relative to the scale factor at room temperature, ratio of the relative change in the gyroscopic scale factor due to temperature change to the change of temperature, generally expressed as a maximum, ppm/°C, %/°C
3.11
maximum input angular rate, Ωmax
maximum input angular rate of gyroscope in forward and reverse directions, within this range, the scale factor nonlinearity of gyroscope meets the specified requirements, (°)/s
3.12
lock-in threshold, Ω
maximum input angular rate at which the gyroscope output is unresponsive under the unbiased condition, it is a synchronization effect between the resonant frequencies of two beams transmitted backwards in the resonator caused by various non-uniformities present in the resonator loop of the gyroscope, (°)/s
3.13
threshold, Ω
minimum input to which the gyroscope may respond, and the output from that input shall be at least 50% of the desired output calculated at the scale factor, (°)/h
3.14
bias, B0
output of gyroscope when the input angular rate is zero, expressed as the equivalent input angular rate corresponding to the average value of output measured within the specified time, (°)/h
3.15
bias stability, Bs
degree of dispersion of the gyroscope output relative to its mean value when the input angular rate is zero, expressed as the equivalent input angular rate corresponding to the standard deviation of the output within the specified time, also referred to as zero drift, (°)/h
3.16
bias repeatability, Br
consistency between biases of gyroscope when it is measured repeatedly under the same conditions and intervals, expressed as the standard deviation of bias obtained from each test, (°)/h
3.17
bias temperature sensitivity, Bt
relative to bias at room temperature, ratio of gyroscope bias change due to temperature variation to temperature variation, generally expressed as the maximum value, (°)/h/°C
3.18
bias magnetic sensitivity, Bm
ratio of gyroscope bias change due to magnetic field to magnetic field strength, (°)/h/mT
3.19
random walk coefficient, RWC
error coefficient of the gyroscope random angle accumulated over time caused by white noise, (°)/h1/2
3.20
warm-up time, Tw
under specified working conditions, time required for the gyroscope to reach the specified performance from energy supply, s
4 General requirements
None.
5 Specific requirements
5.1 Test conditions
5.1.1 Standard atmospheric conditions
a. Ambient temperature: 15~35℃;
b. Relative humidity: 20%~80%;
c. Atmospheric pressure: air pressure at the test site.
5.1.2 Test site
a. The test bench shall be mounted on a separate foundation, and the temperature within the site shall not vary by more than ±2°C;
b. Accurate geographical latitude angle and geographical north reference shall be available at the site;
c. The vibration frequency and amplitude of the base and the magnetic field of the environment shall meet the requirements of product specifications.
5.1.3 Mounting conditions
The gyroscope shall be mounted in the fixture on the test bench, and it is desirable that the mounting conditions be the same as for actual use. The positioning accuracy in each test shall be guaranteed by the accuracy of the test bench and mounting fixture, and shall meet the requirements of product specifications.
5.1.4 Requirements for steering of gyroscope
Looking down on the turntable, it is forward when the turntable rotates counterclockwise. Mount the gyroscope on the turntable. When the turntable rotates forward, the output of the gyroscope is the forward rotation output. According to the right-hand screw rule, the four fingers shall point to the rotating direction of the gyroscope and the thumb shall point to the positive direction of the input axis of the gyroscope.
5.1.5 Requirements for the axis of gyroscope
LA and NA are two mutually perpendicular axes in the laser beam plane. LA passes through the center line of the laser branch containing single electrode (or generating maximum gain in resonator) in gyroscope, and NA bisects the laser branch containing LA, and it can be regarded as an axis of symmetry. LA and NA shall orthogonal to the input axis (IA) of gyroscope, and the positive directions of the three axes shall meet the requirements of ;
IRA, LRA, and NRA are reference axes determined during gyroscope installation, which shall nominally parallel to IA, LA, and NA, respectively, and the positive direction of the three axes shall meet the requirements of . And the three reference axes shall be marked on the gyroscope shell.
5.2 Test equipment
5.2.1 Requirements for accuracy of test equipment
The test equipment shall have a product certificate and be within the validity period of metrological verification.
The accuracy and frequency characteristics of the test equipment shall meet the performance requirements of the gyroscope. The systematic error and accidental error of the test equipment shall be less than one tenth and one third of the corresponding errors of gyroscope, respectively.
5.2.2 Requirements for temperature test chamber
a. Where the gyroscope is in operation in the temperature test chamber, it shall be so positioned that the corresponding requirements for accuracy can be met;
b. The gyroscope mounting fixture shall have good thermal conductivity;
c. The temperature in the temperature test chamber shall be monitored by its internal temperature sensor. Unless otherwise specified, the operating temperature of the gyroscope is considered to be stable when the gyroscope is in operation and the temperature of the component with the greatest heat capacity in it does not vary by more than 2°C per hour at the specified test temperature. Or the operating temperature of the gyroscope is considered to be stable after keeping the gyroscope constant for a certain time at the specified test temperature.
1 Scope
1.1 Subject content
1.2 Application scope
1.3 Application guide
2 Normative references
3 Definitions
4 General requirements
5 Specific requirements
5.1 Test conditions
5.1.1 Standard atmospheric conditions
5.1.2 Test site
5.1.3 Mounting conditions
5.1.4 Requirements for steering of gyroscope
5.1.5 Requirements for the axis of gyroscope
5.2 Test equipment
5.2.1 Requirements for accuracy of test equipment
5.2.2 Requirements for temperature test chamber
5.3 Test item and method
5.3.1 Scale factor
5.3.2 Scale factor nonlinearity
5.3.3 Scale factor asymmetry
5.3.4 Scale factor repeatability
5.3.5 Scale factor temperature sensitivity
5.3.6 Maximum input angular rate
5.3.7 Lock-in threshold
5.3.8 Threshold
5.3.9 Input axis misalignment
5.3.10 Bias
5.3.11 Bias stability
5.3.12 Bias repeatability
5.3.13 Bias temperature sensitivity
5.3.14 Bias magnetic sensitivity
5.3.15 Random walk coefficient
Methods for testing laser gyroscope
1 Scope
1.1 Subject content
This standard specifies the relevant terms of single-axis laser gyroscope (hereinafter referred to as “gyroscope”) and the methods for testing its performance.
1.2 Application scope
This standard is applicable to the performance testing of gyroscopes used on various carriers in the land, sea, air and space fields.
This standard may also serve as a reference for the performance testing of three-axis laser gyroscope.
1.3 Application guide
For the test items listed in this standard, those with the same test equipment and similar test procedures can be tested together as needed, and then their respective test data can be processed with their corresponding calculation methods accordingly.
2 Normative references
GB 321-80 Preferred numbers and preferred number series
GJB 585-88 Inertial technical terms
3 Definitions
Terms not defined in this standard shall be as specified in GJB 585.
3.1
laser gyroscope
device for measuring angular velocity and angle, which is based on sagnac effect and composed of a ring laser resonator, and when it rotates around the vertical line of the equivalent plane of the closed optical path, the resonant frequencies of the two beams transmitted backwards are different, their frequency difference is proportional to the angular velocity of the resonator rotating relative to the inertial space, and the output pulse number is proportional to the rotating angle, so by checking the frequency difference and the pulse number, the angular velocity and rotating angle of the gyroscope can be obtained
3.2
input axis, IA
axis perpendicular to the equivalent plane of the closed optical path, when the gyroscope rotates around this axis, the maximum output will be produced
3.3
input reference axis, IRA
axis perpendicular to the mounting surface of gyroscope, nominally parallel to the input axis
3.4
input axis misalignment, γm
angle between input axis and input reference axis, mrad
3.5
input angular rate, Ω
angular displacement of the gyroscope around the input axis per unit time, also referred to as the input rate, (°)/s
3.6
scale factor, K
ratio of the output to the input of gyroscope, it is proportional to the area of closed loop and inversely proportional to the total length of the optical path and the working wavelength, p/(")
3.7
scale factor nonlinearity, Km
within the range of input angular rate, the ratio of the maximum deviation of gyroscope output to input relative to the scale factor to the scale factor, ppm
3.8
scale factor asymmetry, Ka
within the range of input angular rate, the ratio of the difference of scale factor between the forward and reverse input angular rate of gyroscope and its average value, ppm
3.9
scale factor repeatability, kr
consistency between scale factors of gyroscope when measured repeatedly under the same conditions and at specified intervals, expressed as the ratio of the standard deviation of the scale factors obtained from each test to its average value, ppm, %
3.10
scale factor temperature sensitivity, kt
relative to the scale factor at room temperature, ratio of the relative change in the gyroscopic scale factor due to temperature change to the change of temperature, generally expressed as a maximum, ppm/°C, %/°C
3.11
maximum input angular rate, Ωmax
maximum input angular rate of gyroscope in forward and reverse directions, within this range, the scale factor nonlinearity of gyroscope meets the specified requirements, (°)/s
3.12
lock-in threshold, Ω
maximum input angular rate at which the gyroscope output is unresponsive under the unbiased condition, it is a synchronization effect between the resonant frequencies of two beams transmitted backwards in the resonator caused by various non-uniformities present in the resonator loop of the gyroscope, (°)/s
3.13
threshold, Ω
minimum input to which the gyroscope may respond, and the output from that input shall be at least 50% of the desired output calculated at the scale factor, (°)/h
3.14
bias, B0
output of gyroscope when the input angular rate is zero, expressed as the equivalent input angular rate corresponding to the average value of output measured within the specified time, (°)/h
3.15
bias stability, Bs
degree of dispersion of the gyroscope output relative to its mean value when the input angular rate is zero, expressed as the equivalent input angular rate corresponding to the standard deviation of the output within the specified time, also referred to as zero drift, (°)/h
3.16
bias repeatability, Br
consistency between biases of gyroscope when it is measured repeatedly under the same conditions and intervals, expressed as the standard deviation of bias obtained from each test, (°)/h
3.17
bias temperature sensitivity, Bt
relative to bias at room temperature, ratio of gyroscope bias change due to temperature variation to temperature variation, generally expressed as the maximum value, (°)/h/°C
3.18
bias magnetic sensitivity, Bm
ratio of gyroscope bias change due to magnetic field to magnetic field strength, (°)/h/mT
3.19
random walk coefficient, RWC
error coefficient of the gyroscope random angle accumulated over time caused by white noise, (°)/h1/2
3.20
warm-up time, Tw
under specified working conditions, time required for the gyroscope to reach the specified performance from energy supply, s
4 General requirements
None.
5 Specific requirements
5.1 Test conditions
5.1.1 Standard atmospheric conditions
a. Ambient temperature: 15~35℃;
b. Relative humidity: 20%~80%;
c. Atmospheric pressure: air pressure at the test site.
5.1.2 Test site
a. The test bench shall be mounted on a separate foundation, and the temperature within the site shall not vary by more than ±2°C;
b. Accurate geographical latitude angle and geographical north reference shall be available at the site;
c. The vibration frequency and amplitude of the base and the magnetic field of the environment shall meet the requirements of product specifications.
5.1.3 Mounting conditions
The gyroscope shall be mounted in the fixture on the test bench, and it is desirable that the mounting conditions be the same as for actual use. The positioning accuracy in each test shall be guaranteed by the accuracy of the test bench and mounting fixture, and shall meet the requirements of product specifications.
5.1.4 Requirements for steering of gyroscope
Looking down on the turntable, it is forward when the turntable rotates counterclockwise. Mount the gyroscope on the turntable. When the turntable rotates forward, the output of the gyroscope is the forward rotation output. According to the right-hand screw rule, the four fingers shall point to the rotating direction of the gyroscope and the thumb shall point to the positive direction of the input axis of the gyroscope.
5.1.5 Requirements for the axis of gyroscope
LA and NA are two mutually perpendicular axes in the laser beam plane. LA passes through the center line of the laser branch containing single electrode (or generating maximum gain in resonator) in gyroscope, and NA bisects the laser branch containing LA, and it can be regarded as an axis of symmetry. LA and NA shall orthogonal to the input axis (IA) of gyroscope, and the positive directions of the three axes shall meet the requirements of ;
IRA, LRA, and NRA are reference axes determined during gyroscope installation, which shall nominally parallel to IA, LA, and NA, respectively, and the positive direction of the three axes shall meet the requirements of . And the three reference axes shall be marked on the gyroscope shell.
5.2 Test equipment
5.2.1 Requirements for accuracy of test equipment
The test equipment shall have a product certificate and be within the validity period of metrological verification.
The accuracy and frequency characteristics of the test equipment shall meet the performance requirements of the gyroscope. The systematic error and accidental error of the test equipment shall be less than one tenth and one third of the corresponding errors of gyroscope, respectively.
5.2.2 Requirements for temperature test chamber
a. Where the gyroscope is in operation in the temperature test chamber, it shall be so positioned that the corresponding requirements for accuracy can be met;
b. The gyroscope mounting fixture shall have good thermal conductivity;
c. The temperature in the temperature test chamber shall be monitored by its internal temperature sensor. Unless otherwise specified, the operating temperature of the gyroscope is considered to be stable when the gyroscope is in operation and the temperature of the component with the greatest heat capacity in it does not vary by more than 2°C per hour at the specified test temperature. Or the operating temperature of the gyroscope is considered to be stable after keeping the gyroscope constant for a certain time at the specified test temperature.
Contents of GBJ 2427-1995
1 Scope
1.1 Subject content
1.2 Application scope
1.3 Application guide
2 Normative references
3 Definitions
4 General requirements
5 Specific requirements
5.1 Test conditions
5.1.1 Standard atmospheric conditions
5.1.2 Test site
5.1.3 Mounting conditions
5.1.4 Requirements for steering of gyroscope
5.1.5 Requirements for the axis of gyroscope
5.2 Test equipment
5.2.1 Requirements for accuracy of test equipment
5.2.2 Requirements for temperature test chamber
5.3 Test item and method
5.3.1 Scale factor
5.3.2 Scale factor nonlinearity
5.3.3 Scale factor asymmetry
5.3.4 Scale factor repeatability
5.3.5 Scale factor temperature sensitivity
5.3.6 Maximum input angular rate
5.3.7 Lock-in threshold
5.3.8 Threshold
5.3.9 Input axis misalignment
5.3.10 Bias
5.3.11 Bias stability
5.3.12 Bias repeatability
5.3.13 Bias temperature sensitivity
5.3.14 Bias magnetic sensitivity
5.3.15 Random walk coefficient
