Method for improving high-temperature north-seeking precision of metal resonant gyroscope

Abstract

The invention relates to a method for improving high-temperature north-seeking precision of a metal resonant gyroscope. The method comprises the following steps: S1, acquiring experimental data; s2, controlling the gyroscope to work in a phase calibration state through the upper computer to obtain phase errors of the gyroscope at different temperature points; s3, processing experimental data through upper computer software matlab, performing compensation on a software part in a metal resonator gyroscope control circuit, and performing conventional output-stage temperature compensation after phase error compensation is completed; s4, after phase error and output stage temperature compensation is completed, the metal resonant gyroscope is placed in an incubator rotary table in the same posture, four-position north-seeking experiments are carried out at different temperatures, and north-seeking results output by the gyroscope are collected. According to the method, the phase error of the gyroscope is calibrated at different temperature points, a compensation model of the phase error and the temperature of the gyroscope is established, the amplitude of the gyroscope output along with the temperature change is reduced, the gyroscope precision after conventional compensation is improved, and the high-temperature north-seeking precision of the gyroscope is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of ship navigation systems, and in particular to a method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope. Background Art

[0002] The metal resonant gyroscope is a solid wave gyroscope with simple structure, long life, high reliability and short startup time. It has broad application prospects in the field of attitude measurement. The core sensitive element of the metal resonant gyroscope is the resonator. Due to factors such as structure, processing, and materials, the resonant frequency of the resonator is usually different. When there is no angular velocity input, the metal resonant gyroscope works in the excitation mode. When the angular velocity is input, the four-antinode vibration mode will produce precession under the action of the Coriolis force, such as Figure 3 As shown, vibration will occur at the wave node at this time. After detecting the signal, the external input angular velocity can be calculated.

[0003] As an angular velocity sensitive element, it is used in the downhole north-seeking system while drilling. The principle of gyroscope north-seeking is to measure the component of ground speed in the horizontal plane through the gyroscope sensitive axis, and then obtain the angle with the true north. Commonly used north-seeking methods include two-position north-seeking and four-position north-seeking. Two-position north-seeking is to place the gyroscope horizontally on a turntable, control the gyroscope attitude to be at a position 180° apart through the turntable, and collect the gyroscope output at two positions, which can be expressed as:

[0004]

[0005]

[0006] Where τ is the gyro constant drift, Ω a is the ground speed, and from equations (1) and (2) we get:

[0007]

[0008] The principle of four-position north seeking is similar to that of two-position north seeking. The four-position north seeking solution is simple and is not affected by the local latitude, gyro scale factor and zero bias. The turntable controls the gyro attitude at positions with a difference of 90°, and collects the gyro outputs at four positions, which can be expressed as:

[0009]

[0010] Finally, the north-seeking result can be obtained from (4):

[0011]

[0012] When the metal resonant gyroscope works in a high-temperature environment, the zero-bias stability deteriorates due to the drastic temperature change of the gyroscope itself, resulting in large changes in the gyroscope output and inaccurate output data. Conventional compensation methods cannot completely eliminate this problem, which makes it difficult for the gyroscope to meet the application requirements of the downhole north-seeking while drilling system engineering.

[0013] In view of the above technical problems, the present invention provides a method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope. Summary of the invention

[0014] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope. The phase error of the gyroscope is calibrated at different temperature points, a compensation model of the gyroscope phase error and temperature is established, the amplitude of the gyroscope output changing with temperature is reduced, the gyroscope accuracy after conventional compensation is improved, and the high-temperature north-seeking accuracy of the gyroscope is thereby improved.

[0015] A method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope comprises the following steps:

[0016] S1. Obtain experimental data: Place the metal resonant gyroscope and the control circuit horizontally in the temperature chamber turntable, with the gyroscope sensitive axis parallel to the table surface. Collect temperature information, gyroscope output and gyroscope control signal through the serial port and the host computer software. The temperature chamber runs a fixed-point temperature experiment, with each temperature point interval of 10°C and a temperature range of 20-150°C.

[0017] S2. The gyro is controlled to work in the phase calibration state through the host computer. After the gyro temperature is stable, the metal resonant gyro phase error is calibrated. After the calibration is completed, the temperature of the incubator is set. After repeating the operation, the phase error of the gyro at different temperature points is obtained.

[0018] S3, the experimental data is processed by the host computer software matlab, and a compensation model between temperature and phase error is established, and compensation is performed in the software part of the metal resonant gyroscope control circuit. After the phase error compensation is completed, the metal resonant gyroscope is subjected to a temperature experiment in the same posture, the gyroscope temperature information and output information are collected, and then conventional output stage temperature compensation is performed;

[0019] S4. After completing the phase error and output stage temperature compensation, place the metal resonant gyro in the same posture in the temperature chamber turntable, conduct four-position north-seeking experiments at different temperatures, and collect the gyro output north-seeking results.

[0020] Furthermore, the temperature range in S1 is 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C and 150°C.

[0021] Furthermore, a compensation model between temperature and phase error is established in S3:

[0022]

[0023] In the formula, is the phase error, t is the ambient temperature, a1a2a3a4 are the fitting coefficients;

[0024] y=b1f 3 +b2f 2 +b3f+b4 (8)

[0025] Where y is the gyro output, f is the gyro frequency, and b1b2b3b4 are the fitting coefficients.

[0026] The advantages and positive effects of the present invention are:

[0027] 1. The method of improving the high-temperature north-seeking accuracy of a metal resonant gyroscope of the present invention is applicable to a hemispherical resonant gyroscope and a micromechanical gyroscope, has a wide range of applications, and has a foundation for engineering applications.

[0028] 2. The present invention effectively improves the gyro accuracy by calibrating and compensating the gyro phase error in normal temperature to high temperature environment, thereby improving the high-temperature north-seeking accuracy of the gyro, laying a foundation for the application of metal resonant gyroscopes in downhole north-seeking systems while drilling, and has important engineering significance.

[0029] 3. The present invention calibrates the phase error of the gyroscope at different temperature points, establishes a compensation model for the gyroscope phase error and temperature, reduces the amplitude of the gyroscope output changing with temperature, improves the gyroscope accuracy after conventional compensation, and further improves the high-temperature north-seeking accuracy of the gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a system block diagram of a method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope according to the present invention;

[0031] Figure 2 A flowchart of the method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope according to the present invention;

[0032] Figure 3 This is the working principle diagram of the metal resonant gyroscope; DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0034] like Figures 1 to 3As shown in the figure, there are two types of phase errors in metal resonant gyroscopes. One is that phase errors are generated due to various factors, which in turn cause errors in the control process; the other is that no phase error is generated, but due to the error in measurement, the control system mistakenly believes that a phase offset has occurred, and then the control operation is performed according to the measured wrong phase, causing errors. Phase error will have a series of effects on the gyro control system, and the phase error will change dramatically with temperature changes, seriously affecting the gyro accuracy.

[0035] The principle of gyroscope north finding is to measure the component of ground speed in the horizontal plane through the gyroscope sensitive axis, and then get the angle with the true north. Commonly used north finding methods include two-position north finding and four-position north finding. Two-position north finding is to place the gyroscope horizontally on a turntable, control the gyroscope attitude to be at a position 180° apart through the turntable, and collect the gyroscope output at two positions, which can be expressed as:

[0036]

[0037]

[0038] Where τ is the gyro constant drift, Ω a is the ground speed, and from equations (1) and (2) we get:

[0039]

[0040] The principle of four-position north seeking is similar to that of two-position north seeking. The four-position north seeking solution is simple and is not affected by the local latitude, gyro scale factor and zero bias. The turntable controls the gyro attitude at positions with a difference of 90°, and collects the gyro outputs at four positions, which can be expressed as:

[0041]

[0042] Finally, the north-seeking result can be obtained from (4):

[0043]

[0044] The vibration mechanism of the solid wave gyroscope resonator has been mentioned in many articles, so I will not repeat it here. The output formula of the metal resonator gyroscope is given. Considering the Coriolis force coupling term and the mass, damping, stiffness inhomogeneity and phase coupling of the resonator, we have:

[0045]

[0046] Where: α is the Bryan coefficient of the resonator, Cq is the orthogonal control force, Ω is the external input angular velocity, ω0 is the resonant frequency of the resonator, Q is the quality factor of the resonator, is the error coupling term.

[0047] A method for improving the high-temperature north-seeking accuracy of a metal resonant gyroscope comprises the following steps:

[0048] S1. Obtain experimental data, place the metal resonant gyroscope and the control circuit horizontally in the temperature box turntable, with the gyroscope sensitive axis parallel to the table surface, collect temperature information, gyroscope output and gyroscope control signal through the serial port and the host computer software, control the temperature box to run at 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃ respectively, calibrate the metal resonant gyroscope phase error at each temperature point, and obtain the actual temperature information and corresponding phase error parameters at each temperature. The temperature box is used to provide a constant temperature environment at different temperature points, the turntable is used to verify the accuracy of four-position north-seeking, and the host computer software is used to collect gyroscope output data and modeling data for phase error calibration.

[0049] S2. The upper computer controls the gyro to work in the phase calibration state. After the gyro temperature stabilizes, the metal resonant gyro phase error is calibrated. After the calibration is completed, the temperature of the incubator is set. After repeating the operation, the phase error of the gyro at different temperature points is obtained.

[0050] S3. The experimental data is processed by matlab, and a compensation model between temperature and phase error is established. The compensation model is shown in formula (7). Compensation is performed in the software part of the metal resonant gyroscope control circuit. After the phase error compensation is completed, the metal resonant gyroscope is subjected to temperature experiment in the same posture, the gyroscope temperature information and output information are collected, and then conventional output stage temperature compensation is performed. The compensation model is shown in formula (8); the experimental data is first processed using matlab software, and the 1s smoothed temperature information and phase error parameters are extracted. The two sets of data are fitted using the cftool toolbox to obtain the compensation model between temperature and phase error. The model is compensated in the control circuit software, the metal resonant gyroscope is subjected to temperature experiment in the same posture, the gyroscope temperature information and output information are collected, and then conventional output stage temperature compensation is performed.

[0051]

[0052] In the formula, is the phase error, t is the ambient temperature, a1a2a3a4 are the fitting coefficients;

[0053] y=b1f 3 +b2f 2 +b3f+b4 (8)

[0054] Where y is the gyro output, f is the gyro frequency, and b1b2b3b4 are the fitting coefficients;

[0055] S4. After completing the phase error and output stage temperature compensation, place the metal resonant gyro in the same posture in the temperature box turntable. Control the temperature box to operate at constant temperatures of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C. At each temperature point, control the turntable in position mode at four positions: 0°, 90°, 180°, and 270°. Collect data for 90 seconds at each position. Calculate and evaluate the north-seeking results according to formula (5).

[0056] The present invention aims at the problem of deterioration of zero bias stability caused by drastic temperature changes of the gyroscope itself when the metal resonant gyroscope is working in a high temperature environment, and proposes a gyroscope phase error compensation method. By calibrating the phase error of the gyroscope at different temperature points, a compensation model of the gyroscope phase error and temperature is established, which reduces the amplitude of the gyroscope output changing with temperature, improves the gyroscope accuracy after conventional compensation, and further improves the high temperature north-seeking accuracy of the gyroscope.

[0057] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for improving the high temperature north-seeking accuracy of a metal resonant gyroscope, comprising the following steps: S1. Obtain experimental data: Place the metal resonant gyroscope and the control circuit horizontally in the temperature chamber turntable, with the gyroscope sensitive axis parallel to the table surface. Collect temperature information, gyroscope output and gyroscope control signal through the serial port and the host computer software. The temperature chamber runs a fixed-point temperature experiment, with each temperature point interval of 10°C and a temperature range of 20-150°C. S2. The gyro is controlled to work in the phase calibration state through the host computer. After the gyro temperature is stable, the metal resonant gyro phase error is calibrated. After the calibration is completed, the temperature of the incubator is set. After repeating the operation, the phase error of the gyro at different temperature points is obtained. S3, the experimental data is processed by the host computer software matlab, and a compensation model between temperature and phase error is established, and compensation is performed in the software part of the metal resonant gyroscope control circuit. After the phase error compensation is completed, the metal resonant gyroscope is subjected to a temperature experiment in the same posture, the gyroscope temperature information and output information are collected, and then conventional output stage temperature compensation is performed; S4. After completing the phase error and output stage temperature compensation, place the metal resonant gyro in the same posture in the temperature chamber turntable, conduct four-position north-seeking experiments at different temperatures, and collect the gyro output north-seeking results.

2. The method for improving the high temperature north-seeking accuracy of a metal resonant gyroscope according to claim 1, characterized in that: The temperature range in S1 is 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C and 150°C.

3. The method for improving the high temperature north-seeking accuracy of a metal resonant gyroscope according to claim 1, characterized in that: The compensation model between temperature and phase error is established in S3: In the formula, is the phase error, t is the ambient temperature, a1a2a3a4 are the fitting coefficients; y=b1f 3 +b2f 2 +b3f+b4 (8) Where y is the gyro output, f is the gyro frequency, and b1b2b3b4 are the fitting coefficients.

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