A high-sensitivity frequency modulation gyroscope

Abstract

This invention discloses a high-sensitivity frequency-modulated gyroscope, belonging to the field of microelectromechanical systems (MEMS). Specifically, it includes a driving mass structure, a detection frame structure, an elastic beam structure, a lever coupling structure, a lever amplification structure, a support anchor point, a double-ended fixed resonant beam structure, a resonant beam driving structure, a driving mode driving electrode, a driving mode detection electrode, a detection mode feedback electrode, a double-ended fixed resonant beam driving electrode, and a comb-tooth pair structure. The high-sensitivity frequency-modulated gyroscope structure employed in this invention not only widens the frequency difference between the driving mode and the co-directional interference mode, reducing interference signals, but also achieves digital signal output, exhibiting strong anti-interference capabilities and avoiding quantization noise. Simultaneously, the lever amplification structure amplifies the Coriolis force experienced by the gyroscope's detection mode, increasing the useful signal. These advantages improve the gyroscope's signal-to-noise ratio and sensitivity, contributing to improved gyroscope accuracy.

Description

Technical Field

[0001] This invention relates to a high-sensitivity frequency modulation gyroscope for use in weapon systems, geological exploration, unmanned aerial vehicles, and robot attitude adjustment and navigation positioning systems, belonging to the field of micro-electro-mechanical systems (MEMS). Background Technology

[0002] Micromechanical gyroscopes are inertial sensors created by combining microelectromechanical systems (MEMS) fabrication technology with the requirements of gyroscope technology. They can sensitively detect the angular velocity or absolute angle of a carrier's rotation relative to inertial space. Compared to GPS, they offer autonomous navigation characteristics such as not relying on external information, not radiating energy, and being less susceptible to external interference. Compared to micromechanical rotor gyroscopes, levitation gyroscopes, laser gyroscopes, and fiber optic gyroscopes manufactured using traditional processes, micromechanical gyroscopes have numerous advantages, including small size, light weight, low power consumption, low cost, and ease of mass production, demonstrating their unparalleled advantages and representing one of the main development directions for gyroscopes. They have wide applications in aerospace, missile guidance, attitude control, and navigation positioning, and are particularly popular due to the growing demand in consumer electronics and the booming automotive industry.

[0003] The working principle of a resonant micromechanical gyroscope is based on the energy transfer between two vibration modes caused by the Coriolis force. When the frequencies of the driving and detection modes are equal or when mode matching is achieved, the output of the sensor will increase exponentially with the quality factor of the detection mode.

[0004] In currently available literature and patents, most resonant micromechanical gyroscopes achieve signal detection through capacitance sensing. A parallel-plate capacitor is formed between the gyroscope's movable structure and the fixed electrodes. When an angular velocity is input, the Coriolis force causes displacement of the gyroscope's detection mode, leading to a change in capacitance. Angular velocity is detected by sensing this capacitance change, and the output signal is an analog signal. The angular velocity is superimposed on the output signal through amplitude modulation, thus classifying it as an amplitude-modulated gyroscope. Tuning fork-structured resonant gyroscopes typically use a reverse vibration mode as the driving mode to suppress interference signals from the same-direction mode induced by external acceleration inputs.

[0005] However, analog output tuning fork gyroscopes have the following drawbacks: First, there is a co-directional interference vibration mode near the reverse drive mode, making the drive mode detection end susceptible to interference; Second, the gyroscope output is achieved by detecting changes in capacitance to read out the angular velocity signal, which is an analog output. The signal is easily affected by environmental factors, and quantization noise is introduced during the subsequent analog-to-digital conversion, limiting the gyroscope's accuracy; Third, the Coriolis force is relatively small, resulting in a low signal-to-noise ratio for the output signal and limiting detection accuracy. Summary of the Invention

[0006] The technical problem to be solved by this invention is: in view of the shortcomings of existing amplitude modulation gyroscope technology, this invention proposes a frequency modulation gyroscope with strong anti-interference ability and high sensitivity.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-sensitivity frequency-modulated gyroscope, such as Figure 1 As shown, it includes a driving mass block structure 1, a detection frame structure 2, an elastic beam structure 3, a lever coupling structure 4, a lever amplification structure 5, a support anchor point 6, a double-ended fixed resonant beam structure 7, a resonant beam driving structure 8, a driving mode driving electrode 9, a driving mode detection electrode 10, a detection mode feedback electrode 11, a double-ended fixed resonant beam driving electrode 12, and a comb tooth pair structure 13.

[0009] To ensure accuracy, the left-right direction of the horizontal plane is first defined as the X-direction, and an XOY coordinate system is established within the horizontal plane. The high-sensitivity frequency-modulated gyroscope has a symmetrical structure along the X and Y axes.

[0010] Two driving mass block structures 1 are arranged symmetrically from left to right. The two driving mass block structures 1 are placed in the corresponding detection frame structure 2 and connected to the detection frame structure 2 through an elastic beam structure 3. The elastic beam structure 3 has a stiffness in the X-axis direction that is much greater than its stiffness in the Y-axis direction. At the same time, the two driving mass block structures 1 are also connected by two lever coupling structures 4 above and below them. The two lever coupling structures 4 are fixed by connecting to the support anchor point 6.

[0011] The two driving mass block structures 1 on the left and right generate movement in the Y-axis direction under the action of the driving mode driving electrode 9, and at the same time the driving mode detection electrode 10 is used for driving mode detection; there is also a feedback electrode 11 between the two driving mass block structures 1.

[0012] In the two detection frame structures 2, the left detection frame structure 2 has a reverse "Z"-shaped three-section beam extending to the left from each of its upper and lower corners. The other ends of the two reverse "Z"-shaped beams are fixed to anchor point 6. At the same time, a short beam extends to the left from the middle section of each of the two reverse "Z"-shaped beams. The two short beams are connected by another Y-shaped short beam, so that the two short beams and the Y-shaped short beam form a "C"-shaped structure, surrounding the anchor point 6 to which the other ends of the two reverse "Z"-shaped beams are fixed. The two reverse "Z"-shaped beams and the "C"-shaped structure constitute the lever on the left side. Enlarged structure 5; it can also be seen that the magnification ratio can be adjusted by adjusting the position of the short beams extending to the left from the middle sections of the two inverted "Z" shaped beams, i.e., adjusting the length of the lever arm; two double-ended fixed resonant beams 7 parallel to the X-axis, one end of which is fixed to another anchor point 6, and the other end of which is connected to the Y-direction short beam of the "C"-shaped structure; each of the two double-ended fixed resonant beams 7 is connected to a resonant beam driving structure 8; the resonant beam driving structure 8 is excited by the double-ended fixed resonant beam driving electrode 12 to generate periodic simple harmonic motion along the Y-axis;

[0013] Of the two detection frame structures 2, the right detection frame structure 2 also extends to the right in a structure symmetrical to the left.

[0014] The present invention proposes a high-sensitivity frequency modulation gyroscope with a reverse drive mode such as Figure 2 As shown, the driving mode driving electrode excites the driving mass block to periodically and alternately move towards or against each other along the Y-axis, with the left and right driving mass blocks moving in opposite directions. Because the driving mass blocks are connected by a lever coupling structure, the motion consistency of the two driving mass blocks is very high.

[0015] The detection modes of the gyroscope are as follows Figure 3 As shown, when the system has an angular velocity input, the mass block structure is driven by the Coriolis force to drive the detection frame structure to periodically move in opposite directions or in the opposite direction along the X-axis. The detection frame structure will amplify the Coriolis force through the lever amplification structure and transmit it to the axial direction (i.e., the X-axis direction) of the double-ended fixed resonant beam structure.

[0016] The driving electrodes of the double-ended fixed-beam resonant beam excite the resonant beam driving structure to periodically alternate between moving in opposite directions or in the same direction along the Y-axis. The resonant beam driving structure drives the double-ended fixed-beam resonant beam structure to perform simple harmonic motion. At this time, the vibration frequency of the double-ended fixed-beam resonant beam structure is its own natural frequency, which is determined by geometric parameters and material properties. When there is an angular velocity input to the system, the Coriolis force is transmitted to the axial direction (i.e., the X-axis direction) of the double-ended fixed-beam resonant beam structure. The axial force acting on the double-ended fixed-beam resonant beam structure will change the vibration frequency of the double-ended fixed-beam resonant beam structure. The change in frequency is proportional to the magnitude of the angular velocity. That is, the angular velocity is superimposed on the output signal through frequency modulation. Therefore, it can be classified as a frequency-modulated gyroscope. The magnitude of the angular velocity can be calculated by reading the change in the vibration frequency of the double-ended fixed-beam resonant beam structure.

[0017] The beneficial effects of this invention are:

[0018] The high-sensitivity frequency modulation gyroscope proposed in this invention has the following advantages:

[0019] 1. The driving mass block structures on the left and right sides are coupled together by a lever structure. The lever structure has a good suppression effect on the co-directional interference mode. While keeping the frequency of the reverse driving mode unchanged, it increases the frequency of the co-directional interference mode, widens the frequency difference between the reverse driving mode and the co-directional interference mode, which is conducive to the energy concentration in the frequency band of the driving mode and achieves higher sensitivity. At the same time, it effectively reduces the interference of the co-directional interference mode on the driving mode detection end.

[0020] 2. The gyroscope output measures the angular velocity signal by detecting the change in the resonant frequency of the double-ended fixed resonant beam. The output signal is a digital signal with strong anti-interference ability. At the same time, it avoids the quantization noise in the process of converting the output analog quantity to digital quantity in conventional technical solutions, thus improving the accuracy of the gyroscope.

[0021] 3. The Coriolis force on the gyroscope detection mode is very small. The Coriolis force on the gyroscope detection mode is amplified by the lever amplification structure, which increases the useful signal and improves the signal-to-noise ratio of the output signal.

[0022] The aforementioned advantages compensate for the shortcomings of existing amplitude modulation gyroscope technology, achieving an improvement and optimization of existing technologies. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a high-sensitivity frequency-modulated gyroscope;

[0024] Figure 2 This is a schematic diagram of the high-sensitivity frequency-modulated gyroscope drive mode;

[0025] Figure 3 This is a schematic diagram of the detection mode of a high-sensitivity frequency-modulated gyroscope;

[0026] Figure 4(a) shows the simulation results of the reverse driving mode frequency of the gyroscope structure whose driving mass block structures on the left and right sides are coupled together through the lever structure.

[0027] Figure 4(b) shows the simulation results of the co-directional interference mode frequency of the gyroscope structure whose driving mass block structures on the left and right sides are coupled through the lever structure.

[0028] Figure 5(a) shows the simulation results of the reverse driving mode frequency of the gyroscope structure whose driving mass block structures on the left and right sides are coupled and connected through the elastic beam structure.

[0029] Figure 5(b) shows the simulation results of the co-directional interference mode frequency of the gyroscope structure whose driving mass block structures on the left and right sides are coupled through the elastic beam structure.

[0030] Figure 6 This is a schematic diagram of the signal flow from the input angular velocity signal to the output signal in this invention;

[0031] Figure 7 This is a schematic diagram of the signal flow from the input angular velocity signal to the output signal in a conventional technical solution;

[0032] Figure 8 This is a partially enlarged schematic diagram of the lever amplification structure in the gyroscope structure of the present invention;

[0033] Figure 9 This is a simulation diagram of the magnification effect of the lever amplification structure in the gyroscope structure of this invention;

[0034] In the figure: 1-driving mass block structure, 2-detection frame structure, 3-elastic beam structure, 4-lever coupling structure, 5-lever amplification structure, 6-support anchor point, 7-double-ended fixed resonant beam structure, 8-resonant beam driving structure, 9-driving mode driving electrode, 10-driving mode detection electrode, 11-detection mode feedback electrode, 12-double-ended fixed resonant beam driving electrode, 13-comb tooth pair structure. Detailed Implementation Plan

[0035] The present invention will now be further described in conjunction with the accompanying drawings and embodiments.

[0036] A high-sensitivity frequency-modulated gyroscope, such as Figure 1 As shown, it includes a driving mass block structure 1, a detection frame structure 2, an elastic beam structure 3, a lever coupling structure 4, a lever amplification structure 5, a support anchor point 6, a double-ended fixed resonant beam structure 7, a resonant beam driving structure 8, a driving mode driving electrode 9, a driving mode detection electrode 10, a detection mode feedback electrode 11, a double-ended fixed resonant beam driving electrode 12, and a comb tooth pair structure 13.

[0037] To ensure accuracy, the left-right direction of the horizontal plane is first defined as the X-direction, and an XOY coordinate system is established within the horizontal plane. The high-sensitivity frequency-modulated gyroscope has a symmetrical structure along the X and Y axes.

[0038] Two driving mass block structures 1 are arranged symmetrically from left to right. The two driving mass block structures 1 are placed in the corresponding detection frame structure 2 and connected to the detection frame structure 2 through an elastic beam structure 3. The elastic beam structure 3 has a stiffness in the X-axis direction that is much greater than its stiffness in the Y-axis direction. At the same time, the two driving mass block structures 1 are also connected by two lever coupling structures 4 above and below them. The two lever coupling structures 4 are fixed by connecting to the support anchor point 6.

[0039] The two driving mass block structures 1 on the left and right generate movement in the Y-axis direction under the action of the driving mode driving electrode 9, and at the same time the driving mode detection electrode 10 is used for driving mode detection; there is also a feedback electrode 11 between the two driving mass block structures 1.

[0040] In the two detection frame structures 2, the left detection frame structure 2 has a reverse "Z"-shaped three-section beam extending to the left from each of its upper and lower corners. The other ends of the two reverse "Z"-shaped beams are fixed to anchor point 6. At the same time, a short beam extends to the left from the middle section of each of the two reverse "Z"-shaped beams. The two short beams are connected by another Y-shaped short beam, so that the two short beams and the Y-shaped short beam form a "C"-shaped structure, surrounding the anchor point 6 to which the other ends of the two reverse "Z"-shaped beams are fixed. The two reverse "Z"-shaped beams and the "C"-shaped structure constitute the lever on the left side. Enlarged structure 5; it can also be seen that the magnification ratio can be adjusted by adjusting the position of the short beams extending to the left from the middle sections of the two inverted "Z" shaped beams, i.e., adjusting the length of the lever arm; two double-ended fixed resonant beams 7 parallel to the X-axis, one end of which is fixed to another anchor point 6, and the other end of which is connected to the Y-direction short beam of the "C"-shaped structure; each of the two double-ended fixed resonant beams 7 is connected to a resonant beam driving structure 8; the resonant beam driving structure 8 is excited by the double-ended fixed resonant beam driving electrode 12 to generate periodic simple harmonic motion along the Y-axis;

[0041] Of the two detection frame structures 2, the right detection frame structure 2 also extends to the right in a structure symmetrical to the left.

[0042] The working process of the above-mentioned high-sensitivity frequency modulation gyroscope is as follows:

[0043] Two driving mass block structures 1 move along the Y-axis under the action of driving mode driving electrodes 9. When there is an angular velocity input in the Z-direction, due to the Coriolis effect, the two detection frame structures 2 on the left and right generate stress along the X-axis. This stress is amplified by the lever amplification structure 5, causing the two short beams of the "C"-shaped structure to generate stresses much greater than those of the detection frame structure 2. Since the Y-direction short beams of the "C"-shaped structure are connected to two double-ended fixed resonant beams 7 parallel to the X-axis, the Y-direction short beams of the "C"-shaped structure transfer this stress to the double-ended fixed resonant beams 7. The double-ended fixed resonant beam driving electrode 12 excites the resonant beam driving structure 8 to generate periodic simple harmonic vibrations along the Y-axis. Under the drive of the resonant beam driving structure 8, the two double-ended fixed resonant beams 7 parallel to the X-axis also perform periodic simple harmonic vibrations. Due to the stress transferred from the "C"-shaped structure, the vibration frequency of the double-ended fixed resonant beams 7 will change. Thus, the magnitude of the angular velocity can be obtained by detecting the frequency of the double-ended fixed resonant beams 7.

[0044] Furthermore, several comb-tooth pairs 13 are provided between the driving mode driving electrode 9 and the driving mass block structure 1, between the driving mode detection electrode 10 and the driving mass block structure 1, between the detection mode feedback electrode 11 and the detection frame structure 2, and between the double-ended fixed resonant beam driving electrode 12 and the resonant beam driving structure 8.

[0045] The present invention proposes a high-sensitivity frequency modulation gyroscope with a reverse drive mode such as Figure 2 As shown, the driving mode driving electrode 9 excites the driving mass block to periodically and alternately move towards or away from each other along the Y-axis. Since the driving mass blocks are connected by the lever coupling structure 4, the motion consistency of the two driving mass block structures 1 is very high.

[0046] The detection modes of the gyroscope are as follows Figure 3 As shown, when the system has an angular velocity input, the mass block structure 1 is driven by the Coriolis force to drive the detection frame structure 2 to periodically move in opposite directions or in the opposite direction along the X-axis.

[0047] In this invention, the driving mass block structures on the left and right sides are coupled and connected by a lever structure, which will be further explained below with reference to Figures 4 and 5.

[0048] Figure 4 shows the simulated vibration modes of the driving mass blocks on the left and right sides coupled together via a lever structure. Figure 4(a) shows the mode shape of the reverse driving mode, and Figure 4(b) shows the mode shape of the co-directional disturbance mode. It can be seen that the frequency difference between the two modes is...

[0049] 2783.4-1957.9=825.5Hz (1)

[0050] Figure 5 shows the simulated vibration modes of the driving mass blocks on the left and right sides coupled together through an elastic beam structure. Figure 5(a) is the mode shape of the reverse driving mode, and Figure 5(b) is the mode shape of the co-directional disturbance mode. It can be seen that the frequency difference between the two modes is...

[0051] 2003.6 - 1835.4 = 168.2 Hz (2)

[0052] Comparing the frequency difference results (1) and (2), it can be seen that the driving mass block structures on the left and right sides of the present invention are coupled and connected through a lever structure. Compared with the conventional scheme where the driving mass block structures on the left and right sides are coupled and connected through an elastic beam structure, the frequency difference is larger, increasing by 3.9 times in this embodiment. It can be seen that the lever structure has a good suppression effect on the co-directional interference mode. While keeping the frequency of the reverse driving mode unchanged, it increases the frequency of the co-directional interference mode, widens the frequency difference between the reverse driving mode and the co-directional interference mode, which is conducive to the energy concentration in the frequency band where the driving mode is located, achieving higher sensitivity, and effectively reducing the interference of the co-directional interference mode on the driving mode detection end.

[0053] In this invention, the output signal of the gyroscope structure is the frequency signal of the double-ended fixed beam, and the signal flow from the input angular velocity signal to the output signal is as follows: Figure 6 As shown, there are 7 stages in total; in conventional technical solutions, the output signal of the gyroscope structure is the capacitance signal of the parallel capacitor plates, and the signal flow from the input angular velocity signal to the output signal is as follows: Figure 7 As shown, there are a total of 8 steps.

[0054] Compared to this invention, conventional technical solutions using gyroscope structures involve an additional analog-to-digital conversion stage in the signal flow, introducing quantization noise during the conversion of the output analog signal to a digital signal. Meanwhile, because the output signal of this invention is a digital signal, it is less sensitive to interference such as parasitic capacitance, resulting in stronger resistance to environmental interference.

[0055] This invention employs a lever amplification structure to amplify the Coriolis force, as detailed below in the appendix. Figure 7 Further explanation is needed.

[0056] The formula for the Coriolis force in a gyroscope structure is as follows:

[0057] F corilis =-2A g m eff A x ω n Ω (3)

[0058] This formula A g For angular gain, m eff For Coriolis mass, A x To drive the displacement amplitude, ω nΩ represents the driving frequency, and Ω represents the angular velocity.

[0059] In this embodiment, assuming an angular gain of 0.5, a Coriolis mass of 0.5 mg, a driving displacement amplitude of 5 μm, a driving frequency of 2π*2000 rad, and an angular velocity of 1° / h (equivalent to π / 648000 rad / s), the magnitude of the Coriolis force in the conventional technical solution is calculated as follows:

[0060] F corilis =1.523*10 -13 N (4)

[0061] In this embodiment, one set of structural parameters is used to simulate and calculate the amplification effect; details of the parameters are provided in the appendix. Figure 8 The simulation calculation yields the following axial force:

[0062] F x =7.0058*10 -13 N (5)

[0063] Therefore, the magnification factor is:

[0064] 7.0058*10 -13 / 1.523*10 -13 =4.6 (6)

[0065] Therefore, it can be seen that in this embodiment, the amplification factor of the lever amplification structure is 4.6 times, which plays a role in amplifying the Coriolis force, increasing the useful signal, which is increased by half an order of magnitude in this embodiment, thus improving the signal-to-noise ratio of the output signal.

[0066] The above description of preferred embodiments of the present invention is intended to illustrate the technical features of the present invention in detail, and is not intended to limit the scope of the invention to the specific forms described in the embodiments. Other modifications and variations made in accordance with the spirit of the present invention are also protected by this patent.

Claims

1. A high-sensitivity frequency-modulated gyroscope comprising a drive mass structure 1, characterized in that, Also including detection frame structure 2, elastic beam structure 3, lever coupling structure 4, lever amplification structure 5, support anchor point 6, double-end fixed support resonant beam structure 7, resonant beam driving structure 8, driving mode driving electrode 9, driving mode detection electrode 10, detection mode feedback electrode 11, double-end fixed support resonant beam driving electrode 12, comb-tooth pair structure 13; The left-right direction of the horizontal plane is defined as the X direction, and an XOY coordinate system is established in the horizontal plane; the high-sensitivity frequency modulation gyroscope is a symmetric structure in the X and Y axes; The two driving mass structures 1 are arranged symmetrically left and right, and the left and right driving mass structures 1 are respectively arranged in the corresponding detection frame structures 2 and are connected to the detection frame structures 2 through the elastic beam structures 3, wherein the elastic beam structures 3 have a stiffness in the X axis direction that is much greater than a stiffness in the Y axis direction; meanwhile, the left and right driving mass structures 1 are also connected through the two lever coupling structures 4 above and below, and the two lever coupling structures 4 are fixed through the support anchor points 6; The left and right driving mass structures 1 generate Y axis direction movement under the action of the driving mode driving electrode 9, and the driving mode detection electrode 10 is used for driving mode detection; there is also a feedback electrode 11 between the two driving mass structures 1; Among the left and right detection frame structures 2, the left detection frame structure 2 extends out one inverted "Z" type three-segment beam at each of the upper and lower ends, and the other end of the two inverted "Z" type beams is fixed to the anchor point 6; meanwhile, a short beam is extended out from the middle segment of each of the two inverted "Z" type beams, and the two short beams are connected through another Y direction short beam, so that the two short beams and the Y direction short beam form a "C" type structure around the anchor point 6 outside the other end of the two inverted "Z" type beams; the two inverted "Z" type beams and the "C" type structure constitute the left lever amplification structure 5; it can be seen that by adjusting the position of the short beam extended out from the middle segment of each of the two inverted "Z" type beams, i.e., adjusting the length of the force arm, the amplification ratio can be adjusted; two double-end fixed support resonant beams 7 parallel to the X axis, one end of each of the two double-end fixed support resonant beams 7 is fixed to another anchor point 6, and the other end of each of the two double-end fixed support resonant beams 7 is connected to the Y direction short beam of the "C" type structure; each of the two double-end fixed support resonant beams 7 is connected with a resonant beam driving structure 8; the resonant beam driving structure 8 is excited by the double-end fixed support resonant beam driving electrode 12 to generate periodic simple harmonic vibration along the Y axis; Among the left and right detection frame structures 2, the right detection frame structure 2 also extends out a structure symmetric to the left.

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