Multi-Degree-of-Freedom Micro-Displacement Measurement Device for Hemispherical Resonant Gyroscope

Abstract

The present application discloses a multi-degree-of-freedom micro-displacement measurement device for a hemispherical resonant gyroscope, which adopts a piezoelectric cantilever probe with optimized design and manufacturing, a multi-stage multi-degree-of-freedom displacement stage capable of realizing multi-stage displacement control, a high-frequency acoustic wave excitation module, a picometer-level displacement detection module, etc. It can achieve a detection accuracy of 1 picometer amplitude under high-frequency vibration, providing a new detection means for low-cost and high-precision mass imbalance detection of hemispherical resonant gyroscopes. The detection results can provide a basis for subsequent leveling of hemispherical resonant gyroscopes.

Description

Technical Field

[0001] The present invention relates to a displacement measurement device for a hemispherical resonant gyroscope, and particularly to a displacement measurement device for a hemispherical resonant gyroscope based on a piezoelectric cantilever probe. Background Art

[0002] The excellent performance of the hemispherical resonant gyroscope is limited by the defects of the quartz resonator in it, including mass, stiffness, and damping defects, mass and stiffness defects, which result in the mismatch of the natural frequencies of the two main vibration modes of the quartz resonator, abbreviated as the resonator, causing a significant decline in the performance of the spherical resonant gyroscope in terms of accuracy, reliability, and lifespan. Under the existing manufacturing capabilities, improving the leveling technology of the quartz resonator is the main means to solve the mass imbalance of the quartz resonator.

[0003] In terms of the identification method of the rigid axis position and unbalanced mass of the resonator, according to the leveling theory of unbalanced mass, the accurate identification of the rigid axis position and unbalanced mass of the resonator is the primary condition for achieving high-precision leveling. The frequency difference caused by the density inhomogeneity defect of the quartz resonator will cause the position of the four-wave belly vibration mode of the resonator to drift relative to the direction of the natural axis, resulting in frequency splitting and thus causing an error in the accuracy of the hemispherical resonant gyroscope. Therefore, it is necessary to identify the magnitude and direction of the density inhomogeneity parameter to provide a basis for compensating the first to third density inhomogeneous harmonics using the leveling technology in the follow-up, so as to prepare for improving the accuracy of the gyroscope. Due to the extremely high mass balance index for the hemispherical resonant gyroscope, it is usually required that the mass imbalance detection resolution of the hemispherical resonant gyroscope is better than 2 ppm, and the angle identification accuracy is better than 2°. Therefore, the amplitude detection accuracy in the vibration mode of the hemispherical resonant gyroscope reaches 2 pm. Currently, the detection of the mass imbalance of the hemispherical resonant gyroscope usually uses a laser Doppler instrument. This method has non-contact measurement, high precision, and simple measurement, but the disadvantage is that it is expensive, and carrying out mass production detection will incur huge costs.

[0004] In addition, the resonator is a precision component with high requirements for vibration characteristics, featuring light mass and small volume. When using a contact-type piezoelectric micro-sensor to test its vibration characteristics, factors such as its measurement range, measurement sensitivity, the performance interference of the prestress on the resonator, and the feasibility of sensor preparation need to be considered. At the same time, the accurate detection and extraction of weak piezoelectric signals are also the premise for achieving picometer-level displacement measurement. Summary of the Invention

[0005] The purpose of this application is to construct a low-cost and multi-degree-of-freedom micro-vibration detection device for the resonator, thereby realizing the large-scale application of high-precision hemispherical resonant gyroscopes.

[0006] Some embodiments of the present application provide a multi-degree-of-freedom micro-displacement measurement device for a hemispherical resonant gyroscope, which includes a piezoelectric cantilever beam probe, a multi-stage multi-degree-of-freedom displacement stage, a high-frequency acoustic wave excitation module, and a picometer-level displacement detection module; wherein, the piezoelectric cantilever beam probe is used to detect the picometer-level micro-displacement generated by the resonator of the hemispherical resonant gyroscope under resonance frequency vibration and generate charges representing the micro-displacement; the multi-stage multi-degree-of-freedom displacement stage is configured to position the piezoelectric cantilever beam probe to the measurement position of the resonator and make contact with the resonator; the high-frequency acoustic wave excitation module is configured to generate an acoustic wave signal having the same resonance frequency as the resonator of the hemispherical resonant gyroscope, so as to provide an excitation signal for the resonator; the picometer-level displacement detection module is configured to obtain the charges from the piezoelectric cantilever probe and process the charges to calculate the picometer-level displacement.

[0007] In some embodiments, the piezoelectric cantilever beam probe is optimized and designed based on the dynamic simulation of the resonator. By calculating an optimization problem with the maximum output of the instantaneous charge amount of the piezoelectric cantilever beam probe as the target, the strength of the piezoelectric cantilever beam probe and the threshold of the change degree of the time-history displacement response of the hemispherical resonant gyroscope as the constraint conditions, and the geometric dimensions of the piezoelectric cantilever beam probe, the thickness of the substrate layer of titanium alloy material, the size of the solder pad, the thickness of the piezoelectric layer, and the thickness of the upper electrode of titanium / copper metal material as variables, the optimized structural form of the piezoelectric cantilever beam probe is obtained.

[0008] In some embodiments, the fabrication of the designed piezoelectric cantilever beam probe is based on the MEMS fabrication process, including the steps: First, use a solder pad to weld the substrate layer formed by the substrate wafer and the piezoelectric ceramic layer formed by the piezoelectric ceramic in a vacuum environment to make a composite piezoelectric cantilever beam structure; then, after protecting the piezoelectric ceramic layer, perform precision machining on the substrate layer to turn out a conical probe structure; then, use a magnetron sputtering platform to sputter titanium / copper metal on the surface of the piezoelectric ceramic layer to form an electrode layer; then, use a spin coater to spin coat photoresist on the surface of the electrode layer, and perform MEMS lithography processes such as pre-baking, exposure, development, and post-baking to pattern the photoresist electrode pattern; then, use a copper / titanium electrode etching solution to etch away the exposed part of the electrode layer to form the electrode on the patterned piezoelectric cantilever beam; then, apply a DC electric field to the piezoelectric ceramic layer for polarization to make it generate a piezoelectric effect; and finally, use a high-power laser cutting machine to cleave into individual piezoelectric cantilever beam probes.

[0009] In some embodiments, the multi-stage multi-degree-of-freedom displacement stage includes a three-axis displacement control module, a visual contact feedback module, and a sensor clamping module; wherein, the three-axis displacement control module includes a first displacement control part for controlling the displacement of the first axis, a second displacement control part for controlling the displacement of the second axis, and a third displacement control part for controlling the displacement of the third axis; each of the first displacement control part, the second displacement control part, and the third displacement control part includes a first-stage displacement control unit for controlling a larger displacement range and a second-stage displacement control unit for controlling a smaller displacement range; wherein, a rack and pinion mechanism is used as the first-stage displacement control unit and a piezoelectric ceramic actuator is used as the second-stage displacement control unit.

[0010] In some embodiments, for the second displacement control part, the displacement range of the rack and pinion mechanism is between 0 and 10 mm, and the resolution can reach 10 μm, so as to roughly position the piezoelectric cantilever probe near the center of the resonator; the resolution of the piezoelectric ceramic actuator is 5 nm, and the moving range is 0 to 40 μm. The piezoelectric ceramic actuator is configured to make the piezoelectric cantilever probe perform micro-stepping until it contacts the resonator.

[0011] In some embodiments, the visual contact feedback module includes a high-definition electron microscope and / or a camera, and the high-definition electron microscope and / or the camera are configured to provide a visual feedback signal to the three-axis displacement control module; or the high-definition electron microscope and / or the camera and the third displacement control part form a combined feedback mechanism to provide a combined feedback including a visual feedback signal and a voltage feedback signal to the three-axis displacement control module.

[0012] In some embodiments, the sensor clamping module is used to firmly clamp the piezoelectric cantilever probe; the sensor clamping module includes a lead screw slider mechanism and a clamping head cooperating with the lead screw slider mechanism.

[0013] In some embodiments, the high-frequency acoustic wave excitation module includes a piezoelectric ceramic block or a microphone device, a signal generator, and a power amplifier. Among them, the frequency of the signal generator is set to the starting vibration frequency of the hemispherical resonator gyroscope, and the voltage signal output by the signal generator is output to the piezoelectric ceramic block or the microphone device through the power amplifier, so that the piezoelectric ceramic block or the microphone device generates an acoustic wave signal to excite the hemispherical resonator gyroscope.

[0014] In some embodiments, the picometer-level displacement detection module includes a charge amplifier, a lock-in amplifier, and a displacement calculation module; wherein, the charge amplifier is configured to collect and amplify the charges generated by the piezoelectric cantilever beam probe; the lock-in amplifier is configured to perform frequency locking on the voltage signal output by the charge amplifier, extract the nanovolt-level weak useful signal having the same frequency as the resonance frequency, and filter out the environmental noise signals; the displacement calculation module is configured to use the output of the lock-in amplifier as an input to calculate the picometer-level displacement.

[0015] In some embodiments, the lock-in amplifier adopts a method of external input reference signal or internal input reference signal. If the method of external input reference signal is adopted, a voltage signal output by the signal generator is branched to the external input terminal of the lock-in amplifier.

[0016] The beneficial effects of the measuring device provided by this application are as follows: By adopting the piezoelectric cantilever beam probe with optimized design and manufacturing, the multi-stage multi-degree-of-freedom displacement stage capable of realizing multi-stage displacement control, the high-frequency acoustic wave excitation module, and the picometer-level displacement detection module, etc., the detection accuracy of 1 pm amplitude under high-frequency vibration can be achieved, providing a new detection means for the low-cost and high-precision mass imbalance detection of the hemispherical resonant gyro, and the detection results can provide a basis for the subsequent leveling of the hemispherical resonant gyro. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a schematic structural diagram of the multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonant gyro according to an embodiment of the present application.

[0018] Figure 2 FIG. is a schematic structural diagram of the piezoelectric cantilever beam probe in the multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonant gyro according to an embodiment of the present application.

[0019] Figure 3 FIG. is a schematic flow chart of the manufacturing method of the piezoelectric cantilever beam probe.

[0020] Figure 4 FIG. is a schematic structural diagram of the multi-stage multi-degree-of-freedom displacement stage in the multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonant gyro according to the present application.

[0021] Figure 5 FIG. is a schematic working principle block diagram of the multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonant gyro according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions of the present application will be further described below with reference to the accompanying drawings.

[0023] Generally speaking, the present application proposes a multi-degree-of-freedom micro-displacement measurement device for a hemispherical resonator gyroscope. To make the objectives, technical solutions, and effects of the present invention clearer and more definite, the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The specific structures and functional details disclosed herein are merely representative and are for the purpose of describing exemplary embodiments of the present application. However, the present application can be specifically implemented in many alternative forms and should not be construed as being limited only to the embodiments set forth herein.

[0025] It should be understood that although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly, the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed related items.

[0026] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a", "an" used herein are also intended to include the plural. It should also be understood that the terms "comprises" and / or "comprising" specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not preclude the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0027] It should also be mentioned that in some alternative implementations, the functions / actions mentioned may occur in an order different from that indicated in the drawings. For example, depending on the functions / actions involved, two successive figures shown may actually be executed substantially simultaneously or sometimes in the reverse order.

[0028] As Figure 1An apparatus for measuring multi-degree-of-freedom micro-displacement of a hemispherical resonant gyro provided by an embodiment of the present application mainly consists of a piezoelectric cantilever beam probe 10, a multi-stage multi-degree-of-freedom displacement stage 20, a high-frequency acoustic wave excitation module 30, and a picometer-level displacement detection module 40. Among them, the piezoelectric cantilever beam probe 10 is used to detect picometer-level displacement signals generated by the resonator A of the hemispherical resonant gyro due to mass imbalance during vibration at the resonant frequency; the function of the multi-stage multi-degree-of-freedom displacement stage 20 is to accurately position the piezoelectric cantilever beam probe 10 to the measurement position of the resonator A and generate a small amount of interference contact with the resonator A, so that the piezoelectric cantilever beam probe 10 generates millivolt-level charges. The function of the high-frequency acoustic wave excitation module 30 is to generate an acoustic wave signal with the same resonant frequency as the resonator A, so as to provide an excitation signal for the resonator A.

[0029] As Figure 2 shown, the piezoelectric cantilever beam probe 10 is of a thin sheet type, which includes a composite layer structure composed of a base layer and a piezoelectric ceramic layer. A probe structure 11 in the shape of a cone is provided on the base layer; an electrode structure 12 is formed on the piezoelectric ceramic layer.

[0030] The piezoelectric cantilever beam probe can be designed by an optimization design scheme based on the dynamic simulation of the resonator A. The scheme can be: taking the maximum output of the instantaneous charge amount of the piezoelectric cantilever beam probe 10 as the target, and taking the strength of the piezoelectric cantilever beam probe 10 and the threshold of the change degree of the time history displacement response of the hemispherical resonant gyro as the constraint conditions; an optimization problem with the geometric dimensions of the piezoelectric cantilever beam probe 10, the thickness of the matrix layer of titanium alloy TC4 material, the size of the solder pad, the thickness of the piezoelectric layer (PZT), and the thickness of the upper electrode of titanium / copper metal material as variables, to obtain the structural form of the optimized piezoelectric cantilever beam probe 10.

[0031] In some embodiments, as Figure 3As shown, the fabrication of the designed piezoelectric cantilever probe 10 can be based on MEMS fabrication processes, which may include step S101 of welding the base layer formed by the base sheet and the piezoelectric ceramic layer formed by the piezoelectric ceramic in a vacuum environment using solder pads to form a composite piezoelectric cantilever structure; step S102 of then protecting the piezoelectric ceramic layer and performing precision machining on the base layer to turn out a conical probe structure; step S103 of sputtering titanium / copper metal on the surface of the piezoelectric ceramic layer using a magnetron sputtering platform to form an electrode layer; step S104 of spin-coating photoresist on the surface of the electrode layer using a spin coater and performing MEMS lithography processes such as pre-baking, exposure, development, and post-baking to pattern the photoresist electrode pattern; step S105 of then etching away the exposed part of the electrode layer using a copper / titanium electrode etching solution to form the electrodes on the patterned piezoelectric cantilever; step S106 of then applying a DC electric field to the piezoelectric ceramic layer for polarization to generate a piezoelectric effect; and step S107 of finally forming individual piezoelectric cantilever probes 10 by dicing with a high-power laser cutter.

[0032] As Figure 1 , Figure 4 shown, the multi-stage multi-degree-of-freedom displacement stage 20 includes a three-axis displacement control module 21, a vision contact feedback module 22, and a sensor clamping module 23. Among them, the three-axis displacement control module 21 includes a first displacement control part 211 for controlling the displacement of the first axis, a second displacement control part 212 for controlling the displacement of the second axis, and a third displacement control part 213 for controlling the displacement of the third axis. Each of the first displacement control part 211, the second displacement control part 212, and the third displacement control part 213 includes a first-stage displacement control unit for controlling a larger displacement range and a second-stage displacement control unit for controlling a smaller displacement range. For example, the first displacement control part 211 includes a first displacement control unit 2111 and a second displacement control unit 2112; the second displacement control part 212 includes a third displacement control unit 2121 and a fourth displacement control unit 2122; the third displacement control part 213 includes a fifth displacement control unit 2131 and a sixth displacement control unit 2132;

[0033] Specifically, taking the second displacement control part 212 as an example, the third displacement control unit 2121 it includes adopts a rack and pinion mechanism and uses a manual driving method to control a larger displacement range, with the displacement range between 0 and 10 mm and a resolution of up to 10 μm, roughly positioning the piezoelectric cantilever probe 10 near the center of the resonator A of the hemispherical resonator gyro; the fourth displacement control unit 2122 it includes can adopt a piezoelectric ceramic actuator with a resolution of up to 5 nm and a moving range of 0 to 40 μm, and the piezoelectric ceramic actuator is configured to make the piezoelectric cantilever probe 10 perform micro-stepping, that is, slowly stepping until it contacts the resonator A.

[0034] Similar to the second displacement control section 212, the first displacement control section 211 and the third displacement control section 213 can also respectively adopt a rack and pinion mechanism and a piezoelectric ceramic actuator as the first-stage displacement control unit and the second-stage displacement control unit.

[0035] As Figure 1 shown, the visual contact feedback module 22 uses a high-definition electron microscope 221, or a combined feedback mechanism composed of the high-definition electron microscope 221 and the voltage threshold of the piezoelectric ceramic actuator as the fourth displacement control unit 2122 to detect whether the piezoelectric cantilever probe 10 touches the resonator A. The high-definition electron microscope 221 can independently provide visual feedback for the three-axis displacement control module 21. Or form a combined feedback with the voltage signal feedback of the fourth displacement control unit 2122.

[0036] When the piezoelectric ceramic actuator makes the probe structure 1 of the piezoelectric cantilever probe 10 touch the resonator A of the hemispherical resonator gyro fixed on the fixture from above during the micro-stepping process, the piezoelectric cantilever probe 10 will generate an instantaneous voltage signal due to touching the resonator A. Therefore, the instantaneous voltage signal can be detected, and when it is determined that the detected instantaneous voltage signal exceeds the voltage threshold preset by the piezoelectric ceramic actuator control module, the piezoelectric ceramic actuator is immediately stopped. The setting of the voltage threshold is determined by the piezoelectric sensitivity coefficient of the piezoelectric cantilever probe 10.

[0037] In addition, a camera 223 can also be provided as a supplementary structure of the visual contact feedback module 22, and the contact situation between the piezoelectric cantilever probe 10 and the resonator A is observed through the camera.

[0038] In addition, a camera 223 can also be provided as a supplementary structure of the visual contact feedback module 22, and the contact situation between the piezoelectric cantilever probe 10 and the resonator A can be observed through the camera 223.

[0039] The sensor clamping module 23 is used to firmly clamp the piezoelectric cantilever probe 10. The sensor clamping module 23 can adopt a lead screw slider mechanism 231 in cooperation with a clamping head 232. The clamping head can be driven by the lead screw slider to adjust the clamping force of the clamping head, realize clamping and loosening, and perform firm clamping during the measurement process. The adjustment can be manual. The clamping head can be made of frosted acrylic material.

[0040] As Figure 1 、 Figure 5As shown, the high-frequency acoustic wave excitation module 30 includes a piezoelectric ceramic block or a microphone device 31, a signal generator 32, and a power amplifier 33. The frequency of the signal generator 32 is set to the starting oscillation frequency of the resonator A, especially, for example, 8260 Hz. The voltage signal output by the signal generator 32 is output to the piezoelectric ceramic block or the microphone device 31 through the power amplifier 33, causing the piezoelectric ceramic block or the microphone device 31 to generate an acoustic wave signal.

[0041] As Figure 1 , Figure 5 shown, the picometer-level displacement detection module 40 includes a charge amplifier 41, a lock-in amplifier 42, and a displacement calculation module 43. The charge amplifier 41 collects and amplifies the charges generated by the piezoelectric cantilever probe 10. The lock-in amplifier 42 locks the frequency of the voltage signal output by the charge amplifier 41, extracts the nanovolt-level weak useful signal identical to the resonant frequency, and filters out the environmental noise signals. The lock-in amplifier 42 adopts the method of external input reference signal or internal input reference signal. If the method of external input reference signal is adopted, a path of the voltage signal output by the signal generator 32 can be branched to the external input terminal of the lock-in amplifier 42. If the method of internal input reference signal is adopted, the signal frequency set by the signal generator 32 can be manually input. The output of the lock-in amplifier 42 serves as the input of the displacement calculation module 43, and the picometer-level displacement is calculated by the displacement calculation module 43.

[0042] It should be understood that the implementation examples described herein are only used to illustrate and explain the present invention and are not used to limit the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention fall within the protection scope of the present invention.

Claims

1. A multi-degree-of-freedom micro-displacement measuring device for a hemispherical resonant gyroscope, characterized in that: It includes piezoelectric cantilever beam probe, multi-stage multi-degree-of-freedom translation stage, high-frequency acoustic excitation module, and picometer-level displacement detection module; The high-frequency acoustic wave excitation module is coupled to the hemispherical resonant gyroscope and is configured to generate an acoustic wave signal having the same resonant frequency as the resonator of the hemispherical resonant gyroscope, thereby providing an excitation signal for the resonator; The piezoelectric cantilever beam probe is a thin sheet type, which includes a composite layer structure consisting of a base layer and a piezoelectric ceramic layer, wherein the base layer has a conical probe structure; an electrode structure is formed on the piezoelectric ceramic layer; The multi-stage multi-degree-of-freedom translation stage is configured to position the piezoelectric cantilever beam probe to a measurement position of the resonator and bring it into contact with the resonator, so that the piezoelectric cantilever beam probe generates an electric charge corresponding to the micro-displacement of picometer level generated by the resonator under the vibration of the resonator frequency; The picometer displacement detection module is configured to obtain the charge from the piezoelectric cantilever probe and process the charge to calculate the micro displacement; The multi-stage multi-degree-of-freedom displacement platform includes a three-axis displacement control module, a visual contact feedback module and a sensor clamping module; wherein the three-axis displacement control module includes a first displacement control part for controlling the displacement of the first axis, a second displacement control part for controlling the displacement of the second axis, and a third displacement control part for controlling the displacement of the third axis; each of the first displacement control part, the second displacement control part and the third displacement control part includes a first-stage displacement control unit for controlling a larger displacement range and a second-stage displacement control unit for controlling a smaller displacement range; wherein a rack and pinion mechanism is used as the first-stage displacement control unit and a piezoelectric ceramic actuator is used as the second-stage displacement control unit.

2. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 1, characterized in that: The piezoelectric cantilever probe is obtained based on the dynamic simulation optimization design of the resonator. The optimization design includes: by calculating the optimization problem with the maximum instantaneous charge output of the piezoelectric cantilever probe as the goal, the strength of the piezoelectric cantilever probe and the threshold value of the degree of change of the time-series displacement response of the hemispherical resonant gyroscope as constraints, and the geometric dimensions of the piezoelectric cantilever probe, the substrate layer thickness of the titanium alloy material, the size of the welding piece, the piezoelectric layer thickness, and the upper electrode thickness of the titanium / copper metal material as variables, the optimized structural form of the piezoelectric cantilever probe is obtained.

3. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 2, characterized in that: The designed piezoelectric cantilever beam probe is manufactured based on the MEMS manufacturing process, including the following steps: first, a base layer formed by a base sheet and a piezoelectric ceramic layer formed by a piezoelectric ceramic are welded in a vacuum environment using a welding sheet to form a composite piezoelectric cantilever beam structure; Then, after protecting the piezoelectric ceramic layer, precision machining is performed on the base layer to turn out a conical probe structure; Then, a magnetron sputtering platform is used to sputter titanium / copper metal on the surface of the piezoelectric ceramic layer to form an electrode layer; Then, a photoresist is spin-coated on the surface of the electrode layer by using a coating machine, and then a pre-bake, exposure, development, and post-bake MEMS photolithography process is performed to pattern the photoresist electrode pattern; Then, a copper / titanium electrode etching solution is used to etch away a portion of the exposed electrode layer to form an electrode on the patterned piezoelectric cantilever beam; Then, a direct current electric field is applied to the piezoelectric ceramic layer to polarize it so as to generate a piezoelectric effect; Finally, a single piezoelectric cantilever probe is formed by splitting the piece through a high-power laser cutter.

4. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 1, characterized in that: The displacement range of the rack and pinion mechanism in the second displacement control part is between 0 and 10 mm, and the resolution can reach 10 μm, so that the piezoelectric cantilever beam probe can be roughly positioned near the center of the resonator.

5. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 1, characterized in that: The piezoelectric ceramic actuator has a resolution of 5 nm and a moving range of 0-40 μm. The piezoelectric ceramic actuator is configured to make the piezoelectric cantilever probe perform micro-stepping until it contacts the resonator.

6. The multi-degree-of-freedom micro-displacement measuring device of a hemispherical resonator gyroscope according to claim 1, characterized in that: The visual contact feedback module includes a high-definition electron microscope and / or a camera, and the high-definition electron microscope and / or the camera are configured to provide a visual feedback signal to the three-axis displacement control module; or the high-definition electron microscope and / or the camera and the third displacement control part constitute a joint feedback mechanism to provide the three-axis displacement control module with joint feedback including a visual feedback signal and a voltage feedback signal.

7. The multi-degree-of-freedom micro-displacement measuring device of a hemispherical resonator gyroscope according to claim 1, characterized in that: The sensor clamping module is used to firmly clamp the piezoelectric cantilever beam probe; the sensor clamping module includes a screw slider mechanism and a clamping head matched with the screw slider mechanism.

8. The multi-degree-of-freedom micro-displacement measuring device of a hemispherical resonator gyroscope according to claim 1, characterized in that: The high-frequency sound wave excitation module includes a piezoelectric ceramic block or a microphone device, a signal generator, and a power amplifier; wherein the frequency of the signal generator is set to the starting frequency of the hemispherical resonant gyroscope, and the voltage signal output by the signal generator is output to the piezoelectric ceramic block or the microphone device via the power amplifier, so that the piezoelectric ceramic block or the microphone device generates a sound wave signal to excite the hemispherical resonant gyroscope.

9. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 8, characterized in that: The picometer displacement detection module includes a charge amplifier, a phase-locked amplifier and a displacement calculation module; wherein the charge amplifier is configured to collect and amplify the charge generated by the piezoelectric cantilever probe; the phase-locked amplifier is configured to frequency-lock the voltage signal output by the charge amplifier, extract the nanovolt-level weak useful signal with the same resonant frequency, and filter out the environmental noise signal; the displacement calculation module is configured to use the output of the phase-locked amplifier as input to calculate the micro-displacement.

10. The multi-degree-of-freedom micro-displacement measuring device of the hemispherical resonator gyroscope according to claim 9, characterized in that: The lock-in amplifier adopts an external input reference signal or an internal input reference signal. If the external input reference signal is adopted, the voltage signal output by the signal generator is divided into one path to the external input end of the lock-in amplifier.

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