A method for identifying rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables.

Abstract

This invention relates to a method for identifying the rigid axis azimuth and frequency split of a hemispherical resonator based on orthogonal antinodes and phase shift variables. It belongs to the field of hemispherical resonator gyroscope parameter identification, specifically involving a method for identifying the rigid axis azimuth and frequency split of a hemispherical resonator. The purpose of this invention is to solve the problems of difficulty and inaccuracy in identifying frequency split and rigid axis azimuth during existing hemispherical resonator mass adjustment processes, leading to low gyroscope sensitivity and measurement accuracy. This invention significantly improves the testing efficiency of rigid axis azimuth and frequency split; the testing of rigid axis azimuth and frequency split is not limited by the quality factor; it is not affected by intrinsic frequency drift; it can directly distinguish the high and low frequency axes of the resonator, avoiding the possibility of incorrect leveling direction; the changes in orthogonal antinodes and phase shift are linearly time-dependent, increasing measurement reliability and convenience; and it improves the frequency split adjustment accuracy and efficiency of the hemispherical resonator.

Description

Technical Field

[0001] This invention belongs to the field of hemispherical resonator gyroscope parameter identification, specifically involving a method for identifying the azimuth angle and frequency fragmentation of the rigid axis of a hemispherical resonator. Background Technology

[0002] After undergoing machining processes such as forming, precision grinding, chemical etching, and metallization, hemispherical resonators inevitably exhibit uneven circumferential distribution of mass and stiffness. This uneven distribution leads to different resonant frequencies of the two natural modes in the second-order bending mode. The amplitude axes of the two natural modes are 45° apart, referred to as the rigid axis of the hemispherical resonator. The amplitude axis corresponding to the mode with the higher natural frequency is called the high-frequency axis, and the amplitude axis corresponding to the mode with the lower natural frequency is called the low-frequency axis. The difference between the two natural frequencies is defined as frequency splitting. Frequency splitting causes the standing wave of the hemispherical resonator to exhibit periodic drift during vibration. The smaller the frequency splitting value, the lower the drift rate of the standing wave. For high-precision hemispherical resonator gyroscopes, the frequency splitting of the hemispherical resonator needs to be <0.5 mHz. Ion beams are typically used to correct machining defects in the hemispherical resonator. To ensure the efficiency and accuracy of the correction, it is necessary to accurately identify the frequency splitting and rigid axis of the hemispherical resonator. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of frequency fragmentation and inaccurate identification of rigid axis azimuth angle in the existing hemispherical harmonic oscillator mass tuning process, which leads to low sensitivity and measurement accuracy of the gyroscope. Therefore, this invention proposes a method for identifying the rigid axis azimuth angle and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables.

[0004] The specific process of the method for identifying the rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables is as follows:

[0005] Step 1: Activate the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position;

[0006] When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position.

[0007] Step 2: Use a vacuum turntable to drive the resonator to rotate 22.5° around the resonator's rotation axis, and start the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position.

[0008] When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position.

[0009] Step 3: The rigid axis identification algorithm based on orthogonal antinodes processes the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 1 and the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 2 to obtain the orientation of the hemispherical harmonic oscillator's eigenfrequency axis relative to the center line of the interdigitated electrode at the 0° position, i.e., the rigid axis azimuth angle of the hemispherical harmonic oscillator.

[0010] Step 4: Based on the calculated current rigid axis azimuth angle β of the hemispherical harmonic oscillator ω Calculate the current azimuth angle of the other rigid axis of the hemispherical harmonic oscillator.

[0011] The vacuum turntable drives the resonator to rotate around the resonator's rotation axis to the target angle position, so that the two rigid axes of the hemispherical resonator are aligned with the measurement optical paths of the laser vibrometer at 180° and 225° respectively.

[0012] Start the D / A converter in the standing wave multi-loop control system of the hemispherical resonator so that the angle between the standing wave direction and the center line of the interdigitated electrode at the 0° position is 22.5°, and then disconnect the D / A converter in the standing wave multi-loop control system of the hemispherical resonator.

[0013] Simultaneously, the output signals of the 180° and 225° laser vibrometers are used as the reference signal and input signal, respectively;

[0014] The reference signal and the input signal are connected to the lock-in amplifier, and the phase difference value and the direction of phase increase and decrease displayed on the lock-in amplifier within a fixed time period are recorded.

[0015] Frequency splitting is obtained by linearly fitting the phase difference of the lock-in amplifier output;

[0016] The high-frequency axis and low-frequency axis are identified by observing the direction of phase increase and decrease.

[0017] The beneficial effects of this invention are as follows:

[0018] The harmonic oscillator vibration parameter identification model based on orthogonal antinodes and phase shift variables has the following advantages: ① The testing efficiency of rigid axis azimuth and frequency splitting is greatly improved; ② The testing of rigid axis azimuth and frequency splitting is not limited by the quality factor; ③ The testing of rigid axis azimuth and frequency splitting is not affected by intrinsic frequency drift; ④ It can directly distinguish the high and low frequency axes of the harmonic oscillator, fundamentally avoiding the possibility of incorrect leveling direction; ⑤ The changes in orthogonal antinodes and phase shift are linear with time, increasing the reliability and convenience of measurement. These five points combined improve the frequency splitting tuning accuracy and efficiency of the hemispherical harmonic oscillator.

[0019] Figure 2 Figure a shows the test results of the frequency splitting identification model based on phase shift change for harmonic oscillator frequency splitting. As can be seen from the figure, the phase shift exhibits a linear relationship with time, which is basically consistent with the prediction of the phase shift model. Figure 2 Figure b shows the test results of the rigid axis azimuth identification model based on orthogonal antinodes for rigid axis azimuth. Figure 2 It can be observed that the measured variation curve of the orthogonal antinodes exhibits a linear relationship with time, which is basically consistent with the prediction of the dynamic model of the orthogonal antinodes. Attached Figure Description

[0020] Figure 1 This is a structural diagram of a hemispherical harmonic oscillator standing wave multi-loop control system.

[0021] Figure 2 The figures show experimental results for testing the vibration parameters of a harmonic oscillator. a is the frequency splitting test curve, and b is the intrinsic frequency axis angle test curve. Detailed Implementation

[0022] Specific Implementation Method 1: The specific process of this implementation method for identifying the rigid axis azimuth angle and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables is as follows:

[0023] Step 1: Activate the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position;

[0024] When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position.

[0025] Step 2: Use a vacuum turntable to drive the resonator to rotate 22.5° around the resonator's rotation axis, and start the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position.

[0026] When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position.

[0027] Step 3: The rigid axis identification algorithm based on orthogonal antinodes processes the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 1 and the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 2 to obtain the orientation of the hemispherical harmonic oscillator's eigenfrequency axis relative to the center line of the interdigitated electrode at the 0° position, i.e., the rigid axis azimuth angle of the hemispherical harmonic oscillator.

[0028] Step 4: Based on the calculated current rigid axis azimuth angle β of the hemispherical harmonic oscillator ω Calculate the current azimuth angle of the other rigid axis of the hemispherical harmonic oscillator.

[0029] The vacuum turntable drives the resonator to rotate around the resonator's rotation axis to the target angle position (set), so that the two rigid axes of the hemispherical resonator are aligned with the measurement optical path of the laser vibrometer at 180° and 225° respectively.

[0030] Start the D / A converter in the standing wave multi-loop control system of the hemispherical resonator so that the angle between the standing wave direction and the center line of the interdigitated electrode at the 0° position is 22.5°, and then disconnect the D / A converter in the standing wave multi-loop control system of the hemispherical resonator.

[0031] Meanwhile, the output signals of the 180° and 225° laser vibrometers are used as the reference signal and input signal, respectively (arbitrarily assigned, one-to-one);

[0032] Connect the reference signal and the input signal to the lock-in amplifier (phase meter) and record the phase difference value and the direction of phase increase or decrease displayed on the lock-in amplifier (phase meter) within a fixed time (set);

[0033] Frequency splitting is obtained by linearly fitting the phase difference of the lock-in amplifier output;

[0034] The high-frequency axis and low-frequency axis are identified by observing the direction of phase increase and decrease.

[0035] A hemispherical harmonic oscillator has two frequencies, with the rigid axis having the higher frequency being called the high-frequency axis and the one having the lower frequency being called the low-frequency axis.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the standing wave multi-loop control system of the hemispherical harmonic oscillator includes a signal acquisition part, a control part, and a lock-in amplifier;

[0037] The signal acquisition section consists of two laser vibration meters with 180° and 225° channels.

[0038] The control section consists of an FPGA digital control module, a D / A module, 0° interdigitated electrodes, -180° interdigitated electrodes, 45° interdigitated electrodes, -225° interdigitated electrodes, and a high-voltage amplifier;

[0039] Vibration signal u collected by 225° laser vibrometer dx Vibration signal u collected by 180° laser vibrometer dy The signal is converted into a digital signal by the A / D module, the digital signal is input into the FPGA, the FPGA processes the digital signal, and outputs the processed digital control signal.

[0040] The digital control signal is converted into an analog signal by the D / A module, and the analog signal is amplified by the high voltage amplifier and transmitted to the interdigital electrodes to control the hemispherical resonator; the interdigital electrodes are 0° interdigital electrodes, -180° interdigital electrodes, 45° interdigital electrodes and -225° interdigital electrodes.

[0041] The primary demodulation, secondary demodulation, frequency loop controller, amplitude loop controller, quadrature loop controller, and standing wave azimuth controller used inside the FPGA are the same as those in the traditional hemispherical resonant gyroscope control scheme.

[0042] The other steps and parameters are the same as in Specific Implementation Method 1.

[0043] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the lock-in amplifier is used to receive the vibration signal u collected by the 225° laser vibrometer. dx Vibration signal u collected by 180° laser vibrometer dy The lock-in amplifier outputs the vibration signal u collected by the 225° laser vibrometer. dx Vibration signal u collected by 180° laser vibrometer dy The phase difference between them.

[0044] Other steps and parameters are the same as in specific implementation method one or two.

[0045] Specific Implementation Method Four: This implementation method differs from one of Specific Implementation Methods One to Three in that, in step three, the rigid axis identification algorithm based on orthogonal antinodes processes the voltage signal output by the laser vibration meter controller at the 225° position recorded in step one and the voltage signal output by the laser vibration meter controller at the 225° position recorded in step two to obtain the orientation of the hemispherical harmonic oscillator's intrinsic frequency axis relative to the center line of the interdigitated electrode at the 0° position, i.e., the rigid axis azimuth angle of the hemispherical harmonic oscillator;

[0046] The specific process is as follows:

[0047] Step 3.1. Based on the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 1, calculate the orthogonal amplitude signal of the hemispherical harmonic oscillator. The expression is:

[0048]

[0049] in, The secondary demodulation quantity output by the step hemispherical harmonic oscillator standing wave multi-loop control system;

[0050] q1(t) is the quadrature amplitude signal of the hemispherical harmonic oscillator;

[0051] Step 3.2: Based on the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 2, calculate the orthogonal amplitude signal of the hemispherical harmonic oscillator. The expression is:

[0052]

[0053] in, This is the secondary demodulation output of the hemispherical harmonic oscillator standing wave multi-loop control system in step two;

[0054] q2(t) is the quadrature amplitude signal of the hemispherical harmonic oscillator;

[0055] Step 3: Based on the orthogonal amplitude signals q1(t) and q2(t) of the hemispherical harmonic oscillator, calculate the current azimuth angle of the rigid axis of the hemispherical harmonic oscillator;

[0056]

[0057] in, This represents the first derivative of q1(t);

[0058] This represents the first derivative of q2(t);

[0059] β ω This represents the current azimuth angle of the rigid axis of the hemispherical harmonic oscillator.

[0060] The other steps and parameters are the same as those in one of the specific implementation methods one to three.

[0061] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that, in step four, the current rigid axis azimuth angle β of the hemispherical harmonic oscillator is calculated. ω Calculate the current azimuth angle of the other rigid axis of the hemispherical harmonic oscillator.

[0062] The vacuum turntable drives the resonator to rotate around the resonator's rotation axis to the target angle position (set), so that the two rigid axes of the hemispherical resonator are aligned with the measurement optical path of the laser vibrometer at 180° and 225° respectively.

[0063] Start the D / A converter in the standing wave multi-loop control system of the hemispherical resonator so that the angle between the standing wave direction and the center line of the interdigitated electrode at the 0° position is 22.5°, and then disconnect the D / A converter in the standing wave multi-loop control system of the hemispherical resonator.

[0064] Meanwhile, the output signals of the 180° and 225° laser vibrometers are used as the reference signal and input signal, respectively (arbitrarily assigned, one-to-one);

[0065] Connect the reference signal and the input signal to the lock-in amplifier (phase meter) and record the phase difference value and the direction of phase increase or decrease displayed on the lock-in amplifier (phase meter) within a fixed time (set);

[0066] Frequency splitting is obtained by linearly fitting the phase difference of the lock-in amplifier output;

[0067] The high-frequency axis and low-frequency axis are identified by observing the direction of phase increase and decrease.

[0068] A hemispherical harmonic oscillator has two frequencies, with the rigid axis having the higher frequency being called the high-frequency axis and the one having the lower frequency being called the low-frequency axis.

[0069] The specific process is as follows:

[0070] The reference signal and the input signal are respectively:

[0071]

[0072] Where A0 is the vibration amplitude of the hemispherical harmonic oscillator;

[0073] τ d t is the time constant; t is time.

[0074] ω x ω y These are the two natural circular frequencies of the second-order bending mode of the hemispherical harmonic oscillator;

[0075] ψ1 represents the initial phase of the reference signal;

[0076] ψ2 represents the initial phase of the input signal;

[0077] w x For reference signal;

[0078] w y For input signals;

[0079] Connect the reference signal and the input signal to the lock-in amplifier (phase meter), and record the phase difference value displayed on the lock-in amplifier (phase meter) within a fixed time (set). The expression for the phase difference value is:

[0080] Δψ=(ωx t+ψ1)-(ω y t+ψ2)=(ω x -ω y )t+(ψ1-ψ2)

[0081] Where Δψ is the phase difference output by the lock-in amplifier (phase meter);

[0082] The frequency split is obtained by linearly fitting the phase difference of the lock-in amplifier output, where Δω = |ω x -ω y |

[0083] From the above equation, it can be seen that the phase difference Δψ output by the lock-in amplifier (phase meter) is related to ω. x -ω y As a linear function of time, the phase difference of the lock-in amplifier output is linearly fitted by measuring Δψ over a period of time. The absolute value of the slope of the phase difference output of the lock-in amplifier is the frequency split Δω of the hemispherical harmonic oscillator.

[0084] The other steps and parameters are the same as those in one of the specific implementation methods one to four.

[0085] Theoretical basis:

[0086] The intrinsic frequency axis angle identification algorithm based on orthogonal antinodes and the frequency splitting identification method based on phase shift variables described in steps three and four are further explained.

[0087] The variation of the amplitude of the orthogonal wave antinode of the hemispherical harmonic oscillator with time after the amplitude and orthogonal control loops of the hemispherical harmonic oscillator are as follows:

[0088]

[0089] Where q is the amplitude of the orthogonal antinode, τ is the time constant, θ is the azimuth angle of the standing wave, and β τ β is the azimuth angle of the damping axis. ω denoted as azimuth of the rigid axis, Δω as frequency split, and a as amplitude of the main antinode.

[0090] For a harmonic oscillator with a frequency split below 0.005 Hz and a quality factor greater than 12 million, after disconnecting its amplitude and quadrature control loops, it can be assumed that the azimuth angle of the main wave antinode remains unchanged at the initial angle θ0 and the amplitude of the main wave antinode remains unchanged at the initial amplitude a0 for a short period of time. Then the general solution of equation (1) can be simplified to:

[0091]

[0092] Where t is time.

[0093] Since the initial azimuth of the hemispherical resonator's main wave amplitude axis coincides with the 0° electrode centerline, i.e., the main wave amplitude azimuth angle is 0°, after disconnecting the resonator amplitude and quadrature control loop, the rate of change of the quadrature antinode amplitude is:

[0094]

[0095] Rotating the hemispherical harmonic oscillator 22.5° relative to the 0° electrode position and using the oscillator control system to keep the spherical shell standing wave bound to the 0° electrode position, while still ensuring the amplitude of the main wave antinode is a0 and the amplitude of the orthogonal wave antinode is 0, the rate of change of the orthogonal wave antinode amplitude after disconnecting the amplitude and orthogonal control loops of the hemispherical harmonic oscillator is:

[0096]

[0097] The rigid axis orientation angle of the hemispherical harmonic oscillator is:

[0098]

[0099] During calculation, the quadrature amplitude signal of the hemispherical harmonic oscillator can be obtained through a second demodulation. and get:

[0100]

[0101] The current rigid axis azimuth angle of the hemispherical harmonic oscillator can then be calculated using formula (5).

[0102] The reference signal and the input signal are respectively:

[0103]

[0104] Where A0 is the vibration amplitude of the hemispherical harmonic oscillator;

[0105] τ d t is the time constant; t is time.

[0106] ω x ω y These are the two natural circular frequencies of the second-order bending mode of the hemispherical harmonic oscillator;

[0107] ψ1 represents the initial phase of the reference signal;

[0108] ψ2 represents the initial phase of the input signal;

[0109] w x For reference signal;

[0110] w y For input signals;

[0111] The reference signal and input signal are connected to a lock-in amplifier (phase meter), and the phase difference value displayed on the lock-in amplifier (phase meter) within a fixed time (set) is recorded, that is:

[0112] Δψ=(ω x t+ψ1)-(ω y t+ψ2)=(ω x -ω y )t+(ψ1-ψ2) (8)

[0113] Where Δψ is the phase difference output by the lock-in amplifier (phase meter);

[0114] The frequency split is obtained by linearly fitting the phase difference of the lock-in amplifier output, where Δω = |ω x -ω y |;

[0115] From formula (8), it can be seen that the phase difference Δψ output by the lock-in amplifier (phase meter) is related to ω. x -ω y As a linear function of time, the phase difference of the lock-in amplifier output is linearly fitted by measuring Δψ over a period of time. The absolute value of the slope of the phase difference output of the lock-in amplifier is the frequency split Δω of the hemispherical harmonic oscillator.

[0116] When the vibration signal at the low-frequency axis of the harmonic oscillator shell is the reference signal and the vibration signal at the high-frequency axis is the input signal, the phase difference between the two will increase with time, and the slope Δω calculated by formula (8) will be a positive number. Similarly, when the vibration signal at the high-frequency axis of the harmonic oscillator shell is the reference signal and the vibration signal at the low-frequency axis is the input signal, the phase difference between the two will decrease with time. It can be seen that the high-frequency and low-frequency axes can be directly distinguished by observing the trend of phase increase and decrease.

[0117] This invention may have other embodiments. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method for identifying the azimuth angle and frequency fragmentation of a rigid axis of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables, characterized in that: The specific process of the method is as follows: Step 1: Activate the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position; When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position. Step 2: Use a vacuum turntable to drive the resonator to rotate 22.5° around the resonator's rotation axis, and start the standing wave multi-loop control system of the hemispherical resonator to make the direction of the standing wave consistent with the direction of the center line of the interdigitated electrode at the 0° position. When the standing wave of the hemispherical harmonic oscillator is in a stable state and reaches the target amplitude, disconnect the standing wave multi-loop control system of the hemispherical harmonic oscillator, i.e., the D / A part, and at the same time use the data acquisition card to record the voltage signal output by the laser vibration meter controller at the 225° position. Step 3: The rigid axis identification algorithm based on orthogonal antinodes processes the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 1 and the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 2 to obtain the orientation of the hemispherical harmonic oscillator's eigenfrequency axis relative to the center line of the interdigitated electrode at the 0° position, i.e., the rigid axis azimuth angle of the hemispherical harmonic oscillator. Step 4: Based on the calculated current rigid axis azimuth angle β of the hemispherical harmonic oscillator ω Calculate the current azimuth angle of the other rigid axis of the hemispherical harmonic oscillator. The vacuum turntable drives the resonator to rotate around the resonator's rotation axis to the target angle position, so that the two rigid axes of the hemispherical resonator are aligned with the measurement optical path of the laser vibrometer at 180° and 225° respectively. Start the D / A converter in the standing wave multi-loop control system of the hemispherical resonator so that the angle between the standing wave direction and the center line of the interdigitated electrode at the 0° position is 22.5°, and then disconnect the D / A converter in the standing wave multi-loop control system of the hemispherical resonator. Simultaneously, the output signals of the 180° and 225° laser vibrometers are used as the reference signal and input signal, respectively; The reference signal and the input signal are connected to the lock-in amplifier, and the phase difference value and the direction of phase increase and decrease displayed on the lock-in amplifier within a fixed time period are recorded. Frequency splitting is obtained by linearly fitting the phase difference of the lock-in amplifier output; The high-frequency axis and low-frequency axis are identified by observing the direction of phase increase and decrease.

2. The method for identifying the rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables according to claim 1, characterized in that: The standing wave multi-loop control system of the hemispherical harmonic oscillator includes a signal acquisition section, a control section, and a lock-in amplifier; The signal acquisition section consists of two laser vibration meters with 180° and 225° channels. The control section consists of an FPGA digital control module, a D / A module, 0° interdigitated electrodes, -180° interdigitated electrodes, 45° interdigitated electrodes, -225° interdigitated electrodes, and a high-voltage amplifier; Vibration signal u collected by 225° laser vibrometer dx Vibration signal u collected by 180° laser vibrometer dy The signal is converted into a digital signal by the A / D module, the digital signal is input into the FPGA, the FPGA processes the digital signal, and outputs the processed digital control signal. The digital control signal is converted into an analog signal by the D / A module, and the analog signal is amplified by the high voltage amplifier and transmitted to the interdigital electrodes to control the hemispherical resonator; the interdigital electrodes are 0° interdigital electrodes, -180° interdigital electrodes, 45° interdigital electrodes and -225° interdigital electrodes.

3. The method for identifying the rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables according to claim 2, characterized in that: The lock-in amplifier is used to receive the vibration signal u collected by the 225° laser vibrometer. dx Vibration signal u collected by 180° laser vibrometer dy The lock-in amplifier outputs the vibration signal u collected by the 225° laser vibrometer. dx Vibration signal u collected by 180° laser vibrometer dy The phase difference between them.

4. The method for identifying the rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables according to claim 3, characterized in that: In step three, the rigid axis identification algorithm based on orthogonal antinodes processes the voltage signal output by the laser vibration meter controller at the 225° position recorded in step one and the voltage signal output by the laser vibration meter controller at the 225° position recorded in step two to obtain the orientation of the hemispherical harmonic oscillator's eigenfrequency axis relative to the center line of the interdigitated electrode at the 0° position, i.e., the rigid axis azimuth angle of the hemispherical harmonic oscillator. The specific process is as follows: Step 3.

1. Based on the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 1, calculate the orthogonal amplitude signal of the hemispherical harmonic oscillator. The expression is: in, The secondary demodulation quantity output by the step hemispherical harmonic oscillator standing wave multi-loop control system; q1(t) is the quadrature amplitude signal of the hemispherical harmonic oscillator; Step 3.2: Based on the voltage signal output by the laser vibrometer controller at the 225° position recorded in Step 2, calculate the orthogonal amplitude signal of the hemispherical harmonic oscillator. The expression is: in, This is the secondary demodulation output of the hemispherical harmonic oscillator standing wave multi-loop control system in step two. q2(t) is the quadrature amplitude signal of the hemispherical harmonic oscillator; Step 3: Based on the orthogonal amplitude signals q1(t) and q2(t) of the hemispherical harmonic oscillator, calculate the current azimuth angle of the rigid axis of the hemispherical harmonic oscillator; in, This represents the first derivative of q1(t); This represents the first derivative of q2(t); β ω This represents the current azimuth angle of the rigid axis of the hemispherical harmonic oscillator.

5. The method for identifying the rigid axis azimuth and frequency fragmentation of a hemispherical harmonic oscillator based on orthogonal antinodes and phase shift variables according to claim 4, characterized in that: In step four, the current rigid axis azimuth angle β of the hemispherical harmonic oscillator is calculated. ω Calculate the current azimuth angle of the other rigid axis of the hemispherical harmonic oscillator. The vacuum turntable drives the resonator to rotate around the resonator's rotation axis to the target angle position, so that the two rigid axes of the hemispherical resonator are aligned with the measurement optical path of the laser vibrometer at 180° and 225° respectively. Start the D / A converter in the standing wave multi-loop control system of the hemispherical resonator so that the angle between the standing wave direction and the center line of the interdigitated electrode at the 0° position is 22.5°, and then disconnect the D / A converter in the standing wave multi-loop control system of the hemispherical resonator. Simultaneously, the output signals of the 180° and 225° laser vibrometers are used as the reference signal and input signal, respectively; The reference signal and the input signal are connected to the lock-in amplifier, and the phase difference value and the direction of phase increase and decrease displayed on the lock-in amplifier within a fixed time period are recorded. Frequency splitting is obtained by linearly fitting the phase difference of the lock-in amplifier output; The high-frequency axis and low-frequency axis are identified by observing the direction of phase increase and decrease. The specific process is as follows: The reference signal and the input signal are respectively: Where A0 is the vibration amplitude of the hemispherical harmonic oscillator; τ d t is the time constant; t is time. ω x ω y These are the two natural circular frequencies of the second-order bending mode of the hemispherical harmonic oscillator; ψ1 represents the initial phase of the reference signal; ψ2 represents the initial phase of the input signal; w x For reference signal; w y For input signals; Connect the reference signal and the input signal to the lock-in amplifier, and record the phase difference value displayed on the lock-in amplifier within a fixed time period. The expression for the phase difference value is: Δψ=(ω x t+ψ1)-(ω y t+ψ2)=(ω x -oh y )t+(ψ1-ψ2) Where Δψ is the phase difference of the lock-in amplifier output; The frequency split is obtained by linearly fitting the phase difference of the lock-in amplifier output, where Δω = |ω x -ω y |

Images