A highly integrated micromechanical accelerometer-gyroscope

Abstract

The application discloses a high-integration micromechanical accelerometer-gyroscope, and belongs to the technical field of inertial sensing. The application can realize the resonance driving, amplitude detection and frequency detection of the three-axis structure simultaneously by applying a pair of DC voltages with opposite signs, resonance voltages and carrier voltages on the symmetrical parallel-plate capacitor structure, combining with the PLL phase closed-loop control method, can obtain the force balance feedback voltage through the weighted fusion and controller calculation, maintains the mass block position constant, at this time, the feedback voltage reflects the acceleration size; meanwhile, the three-axis resonance structure is subjected to the Coriolis force coupling effect, the sum of the resonance frequencies of the two orthogonal axes contains the angular velocity information of the third orthogonal axis, and the angular velocity size can be obtained through the multiplication demodulation and low-pass filtering calculation with a sine signal with a frequency difference between the two frequencies. The micromechanical accelerometer-gyroscope integration method is simple, and the temperature drift can be effectively inhibited.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inertial sensing, and more particularly, relates to a highly integrated micro-mechanical accelerometer- gyroscope. BACKGROUND

[0002] Micro-mechanical accelerometers and gyroscopes are sensors for measuring acceleration and angular velocity, and are widely used in consumer electronics, automotive and unmanned aerial vehicle systems. A micro inertial measurement unit (MIMU) is composed of a 3-axis accelerometer and a 3-axis gyroscope, and the two types of sensors are usually in independent structures, with low integration. A few micro-mechanical accelerometer-gyroscope integrated sensors also use different sensitive elements or detection modules to measure acceleration and angular velocity, respectively. Although the acceleration detection module and the angular velocity detection module can be decoupled from each other, there is mutual interference due to the use of the same decoupling sensitive element or detection method. SUMMARY

[0003] In view of the shortcomings and deficiencies of the existing micro-mechanical accelerometer-gyroscope integrated sensors, the present application provides a highly integrated micro-mechanical accelerometer-gyroscope, which integrates an amplitude modulation / frequency modulation (AM / FM) composite accelerometer and a Lissajous frequency modulation (LFM) gyroscope together, and uses the same sensitive structure and resonance detection module to simultaneously realize XYZ three-axis acceleration and XYZ three-axis angular velocity detection. The present application can improve the integration of the sensor and reduce the mutual interference between acceleration and angular velocity detection by combining the amplitude modulation / frequency modulation detection method.

[0004] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0005] A highly integrated micro-mechanical accelerometer-gyroscope adopts an XYZ three-degree-of-freedom mass-spring-damper system as a shared sensitive structure, and comprises:

[0006] A mass block assembly is symmetrical about the Y axis, and comprises a middle mass block, a torsional mass block located inside the middle mass block, and a pair of X-axis mass blocks and a pair of Y-axis mass blocks symmetrically distributed around the middle mass block about the center; the X-axis mass blocks and the Y-axis mass blocks are connected to the middle mass block through X-axis decoupling springs and Y-axis decoupling springs, respectively, and are connected to the anchor area through X-axis mass block support springs and Y-axis mass block support springs, respectively; the torsional mass block is connected to the middle mass block through a pair of Y-axis torsional elastic beams; and the mass block assembly is located in the same XY plane.

[0007] An XYZ-axis symmetric parallel plate capacitor, comprising a pair of first X-axis symmetric parallel plate electrodes located in the negative direction of the X-axis, a pair of second X-axis symmetric parallel plate electrodes located in the positive direction of the X-axis, a pair of first Y-axis symmetric parallel plate electrodes located in the negative direction of the Y-axis, a pair of second Y-axis symmetric parallel plate electrodes located in the positive direction of the Y-axis, and a pair of first Z-axis symmetric parallel plate electrodes and a pair of second Z-axis symmetric parallel plate electrodes located on the same side of the Z-axis;

[0008] An XYZ-axis driver includes an XY-axis variable-area comb driver and a Z-axis variable-pitch driver. The XY-axis variable-area comb driver includes a first X-axis variable-area comb electrode located in the negative direction of the X-axis, a second X-axis variable-area comb electrode located in the positive direction of the X-axis, a first Y-axis variable-area comb electrode located in the negative direction of the Y-axis, and a second Y-axis variable-area comb electrode located in the positive direction of the Y-axis. The Z-axis variable-pitch driver includes a pair of first Z-axis variable-pitch drive electrodes and a pair of second Z-axis variable-pitch drive electrodes located on the same side of the Z-axis.

[0009] As a preferred embodiment of the present invention, the first X-axis symmetric parallel plate electrode and the second X-axis symmetric parallel plate electrode are fixed in the anchor region and are symmetrically distributed about the Y axis;

[0010] The first X-axis variable area comb-tooth electrode and the second X-axis variable area comb-tooth electrode are fixed in the anchor area and are symmetrically distributed about the Y axis;

[0011] The first X-axis symmetric parallel plate electrode and the movable parallel plate electrode installed on the left side / right side of an X-axis mass form a parallel plate capacitor, and the first X-axis variable area comb electrode and the movable comb teeth on the right side / left side of the same X-axis mass form a comb capacitor;

[0012] The second X-axis symmetric parallel plate electrode and the movable parallel plate electrode installed on the right / left side of another X-axis mass block form a parallel plate capacitor, and the second X-axis variable area comb electrode and the movable comb teeth on the left / right side of the same X-axis mass block form a comb capacitor.

[0013] As a preferred embodiment of the present invention, the first Y-axis symmetric parallel plate electrode and the second Y-axis symmetric parallel plate electrode are fixed in the anchor region and are symmetrically distributed about the X-axis;

[0014] The first Y-axis variable area comb-tooth electrode and the second Y-axis variable area comb-tooth electrode are fixed in the anchor region and are symmetrically distributed about the X-axis;

[0015] The first Y-axis symmetric parallel plate electrode and the movable parallel plate electrode mounted on the lower side / upper side of a Y-axis mass form a parallel plate capacitor, and the first Y-axis variable area comb electrode and the movable comb teeth on the upper side / lower side of the same Y-axis mass form a comb capacitor;

[0016] The second Y-axis symmetric parallel plate electrode and the movable parallel plate electrode installed on the upper / lower side of another Y-axis mass block form a parallel plate capacitor, and the second Y-axis variable area comb electrode and the movable comb teeth on the lower / upper side of the same Y-axis mass block form a comb capacitor.

[0017] As a preferred embodiment of the present invention, the pair of first Z-axis symmetric parallel plate electrodes and the pair of second Z-axis symmetric parallel plate electrodes are fixed on a substrate parallel to the mass block assembly, with a gap between them and the torsion mass block; wherein the pair of first Z-axis symmetric parallel plate electrodes are symmetric about the X-axis, the pair of second Z-axis symmetric parallel plate electrodes are symmetric about the X-axis, and the pair of first Z-axis symmetric parallel plate electrodes and the pair of second Z-axis symmetric parallel plate electrodes are symmetric about the Y-axis;

[0018] A pair of first Z-axis symmetric parallel plate electrodes and a movable parallel plate electrode mounted on the top or bottom of the torsional mass form a pair of parallel plate capacitors;

[0019] A pair of second Z-axis symmetric parallel plate electrodes and a movable parallel plate electrode mounted on the top or bottom of the torsional mass form a pair of parallel plate capacitors;

[0020] The two pairs of parallel plate capacitors are initially in a centrosymmetrical structure.

[0021] As a preferred embodiment of the present invention, the pair of first Z-axis variable-spacing driving electrodes and the pair of second Z-axis variable-spacing driving electrodes are fixed on a substrate parallel to the mass block assembly, with a gap between them and the torsion mass block; wherein the pair of first Z-axis variable-spacing driving electrodes are symmetrical about the X-axis, the pair of second Z-axis variable-spacing driving electrodes are symmetrical about the X-axis, and the pair of first Z-axis variable-spacing driving electrodes and the pair of second Z-axis variable-spacing driving electrodes are symmetrical about the Y-axis;

[0022] A pair of first Z-axis variable pitch driving electrodes and a movable parallel plate electrode mounted on the top or bottom of the torsion mass form a pair of Z-axis variable pitch drivers;

[0023] A pair of second Z-axis variable pitch driving electrodes and a movable parallel plate electrode mounted on the top or bottom of the torsional mass form a pair of Z-axis variable pitch drivers;

[0024] The two pairs of variable-pitch drivers are centrally symmetrical in structure.

[0025] As a preferred embodiment of the present invention, the X-axis decoupling spring has a smaller elastic coefficient in the X-axis and a larger elastic coefficient in the Y-axis and Z-axis; the Y-axis decoupling spring has a smaller elastic coefficient in the Y-axis and a larger elastic coefficient in the X-axis and Z-axis; the Y-axis torsional elastic beam has a smaller torsional elastic coefficient around the Y-axis and a larger torsional elastic coefficient around the X-axis and Z-axis.

[0026] As a preferred embodiment of the present invention, the torsional mass block has a non-centrosymmetrical seesaw structure.

[0027] As a preferred embodiment of the present invention, a method for detecting uniaxial acceleration includes:

[0028] Apply a DC voltage V with opposite signs to two pairs of symmetrical parallel plate electrodes on the target axis. di and -V di , resonant voltage A i sin(ω i t) and -A i sin(ω i t), carrier voltage A ci sin(ω ci t) and -A ci sin(ω ci t), obtain the signal of the intermediate mass block and demodulate it to obtain the target axis resonance amplitude and resonance frequency; where A i 、ω i Represents the resonant voltage amplitude and frequency, A ci 、ω ci Indicates the carrier voltage amplitude and frequency, t indicates time, and the subscript i is any one of X, Y, and Z. When i = X, it corresponds to detecting the acceleration of the X axis, when i = Y, it corresponds to detecting the acceleration of the Y axis, and when i = Z, it corresponds to detecting the acceleration of the Z axis.

[0029] The detected target axis resonance amplitude and resonance frequency are deviated from the preset amplitude and frequency, and the difference is multiplied by the preset weight of the resonance amplitude deviation and the preset weight of the resonance frequency deviation respectively, and then the sum is input into the PID controller to calculate the force balance feedback voltage. After passing through the push-pull circuit, it is applied to the target axis driver to drive the corresponding mass block to keep the displacement constant. At this time, the force balance feedback voltage reflects the acceleration of the target axis.

[0030] As a preferred embodiment of the present invention, a method for detecting a single-axis angular velocity includes:

[0031] When the target axis generates angular velocity, the single-axis acceleration detection method is used to obtain the resonant frequencies of the two single axes other than the target axis;

[0032] The sum and difference of the resonant frequencies of the two single axes other than the target axis are obtained respectively;

[0033] A sinusoidal signal with a frequency equal to the difference between the resonant frequencies is generated, and the sum of the resonant frequencies is multiplied, demodulated, and low-pass filtered using the sinusoidal signal to obtain the target shaft angular velocity.

[0034] As a preference of the present invention, when detecting angular velocity, the two single axes except the target axis operate in the amplitude modulation accelerometer operating mode, that is, the preset weight of the resonance amplitude deviation is 1, and the preset weight of the resonance frequency deviation is set to 0.

[0035] The present invention designs a symmetrical parallel plate capacitor structure and applies a pair of voltages with opposite signs on it, including a DC voltage, a resonant voltage, and a carrier voltage. In combination with the PLL phase closed-loop control method, the present invention can simultaneously realize the resonant drive, amplitude modulation detection, and frequency modulation detection of the three-axis structure. On the one hand, when there is external acceleration, the parallel plate electrode fixed to the mass block is displaced. At this time, the symmetrical parallel plate capacitor generates an eccentric resonant force, which is expressed as F d =4εAV d V a x / d 2 , where ε, A, V d 、V a , x, and d are the dielectric constant, parallel plate overlap area, DC voltage, AC excitation voltage, displacement, and parallel plate gap, respectively. The resonant force generates a certain resonant amplitude under PLL control, that is, the displacement caused by acceleration is amplitude modulated into a resonant amplitude variation. At the same time, due to the soft spring effect of the symmetrical parallel plate capacitor, the resonant frequency is approximately linearly related to the displacement of the parallel plate electrode connected to the mass block, and the expression is f = f0-2εAV d 2 x / (md 4 f0), where f0 is the initial resonant frequency, that is, the displacement caused by acceleration is frequency-modulated into a resonant frequency change; the resonant amplitude change and the resonant frequency change caused by acceleration can be simultaneously detected by amplitude modulation-demodulation and a phase-locked loop, respectively. The difference is calculated by comparing with the preset amplitude and preset frequency, and a force balance feedback voltage is obtained through weighted fusion and controller calculation. By applying it to the variable-area comb drive, the position of the mass block can be maintained constant. At this time, the feedback voltage reflects the magnitude of the acceleration; on the other hand, when there is a rotational angular velocity, the resonant structure shared by the two orthogonal axes is coupled by the Coriolis force, and the sum of the resonant frequencies of the two orthogonal axes contains the angular velocity information of the third orthogonal axis. The angular velocity can be obtained by multiplying, demodulating and low-pass filtering with a sinusoidal signal with a frequency equal to the difference between the resonant frequencies of the two orthogonal axes.

[0036] Since acceleration and angular velocity detection use the same mechanical structure and resonant detection principle, interference between signals is avoided, resulting in higher reliability and higher integration. At the same time, since acceleration detection uses an amplitude modulation / frequency modulation composite detection method, it can reduce the temperature drift of the mechanical structure, and the angular velocity uses a frequency modulation detection method with better scale factor stability.

[0037] In general, the technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0038] (1) The present application simplifies the structure and circuit by sharing the mechanical structure and electrodes, improves the space utilization and integration of the micro mechanical device, and has the advantages of simple processing technology, high integration and miniaturization.

[0039] (2) In the present application, the accelerometer and the gyroscope both work in the resonant state, and share a set of PLL control algorithm, which reduces the complexity of the control system and avoids the mutual interference between the signals.

[0040] (3) The accelerometer of the present application can work flexibly in the frequency modulation / amplitude modulation mode and its mixed mode. When the accelerometer works in amplitude modulation and the gyroscope works in frequency modulation, the interference in detection is avoided, and the method is easy to realize in a digital controller. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a typical micro mechanical accelerometer- gyroscope integrated structure schematic diagram in the embodiment of the present application;

[0042] Figure 2 is a typical micro mechanical accelerometer- gyroscope XY axis integrated control method schematic diagram in the embodiment of the present application;

[0043] Figure 3 is a typical micro mechanical accelerometer- gyroscope XZ axis integrated control method schematic diagram in the embodiment of the present application;

[0044] Figure 4 is a typical micro mechanical accelerometer- gyroscope YZ axis integrated control method schematic diagram in the embodiment of the present application; Figure 5 is a frequency modulation / amplitude modulation accelerometer working mode schematic diagram in the embodiment of the present application;

[0045] In all the drawings, the same reference signs are used to represent the same structures, wherein: 1 - middle mass; 21 - X-axis mass, 22 - first X-axis symmetrical parallel plate electrode, 23 - second X-axis symmetrical parallel plate electrode, 24 - first X-axis variable area comb electrode, 25 - second X-axis variable area comb electrode, 26 - X-axis decoupling spring, 27 - X-axis mass support spring; 31 - Y-axis part including Y-axis mass, 32 - first Y-axis symmetrical parallel plate electrode, 33 - second Y-axis symmetrical parallel plate electrode, 34 - first Y-axis variable area comb electrode, 35 - second Y-axis variable area comb electrode, 36 - Y-axis decoupling spring, 37 - Y-axis mass support spring; 41 - torsional mass, 42 - first Z-axis symmetrical parallel plate electrode, 43 - second Z-axis symmetrical parallel plate electrode, 44 - first Z-axis variable interval driving electrode, 45 - second Z-axis variable interval driving electrode, 46 - Y-axis torsional elastic beam; 5 - anchor area. DETAILED DESCRIPTION

[0046] In order to more clearly express the purpose, technical solutions and advantages of the present invention, the following is a further explanation with reference to the accompanying drawings and formula derivations. It should be understood that the principles herein are used to explain the present invention, but are not limited to the present invention.

[0047] The highly integrated micro-mechanical accelerometer-gyroscope in the present invention shares a mechanical structure and adopts an XYZ three-degree-of-freedom mass-spring-damper system as a common sensitive structure. For the convenience of explanation, it is structurally divided into a main mass block part, an X-axis part, a Y-axis part, a Z-axis part and an anchor area part; wherein the main mass block part is an intermediate mass block 1, and the X-axis part includes an X-axis mass block 21, a first X-axis symmetrical parallel plate electrode 22, a second X-axis symmetrical parallel plate electrode 23, a first X-axis variable area comb electrode 24, a second X-axis variable area comb electrode 25, an X-axis decoupling spring 26, an X-axis symmetrical parallel plate electrode 27, a first X-axis variable area comb electrode 28, a second X-axis variable area comb electrode 29, an X-axis symmetrical parallel plate electrode 30, an X-axis symmetrical parallel plate electrode 31, an X-axis symmetrical parallel plate electrode 32, an X-axis symmetrical parallel plate electrode 33, an X-axis symmetrical parallel plate electrode 34, an X-axis symmetrical parallel plate electrode 35, an X-axis symmetrical parallel plate electrode 36, an X-axis symmetrical parallel plate electrode 37, an X-axis symmetrical parallel plate electrode 38, an X-axis symmetrical parallel plate electrode 39, an X-axis symmetrical parallel plate electrode 40, an X-axis symmetrical parallel plate electrode 41, an X-axis symmetrical parallel plate electrode 42, an X-axis symmetrical parallel plate electrode 43, an X-axis symmetrical parallel plate electrode 44, an X-axis symmetrical parallel plate electrode 45, an X-axis symmetrical parallel plate electrode 46, an X-axis symmetrical parallel plate electrode 47, an X-axis symmetrical parallel plate electrode 48, an X-axis symmetrical parallel plate electrode 49, an X-axis symmetrical parallel plate electrode 50, an X-axis symmetrical parallel plate The Y-axis portion includes a Y-axis mass block supporting spring 27; the Y-axis portion includes a Y-axis mass block 31, a first Y-axis symmetrical parallel plate electrode 32, a second Y-axis symmetrical parallel plate electrode 33, a first Y-axis variable-area comb electrode 34, a second Y-axis variable-area comb electrode 35, a Y-axis decoupling spring 36 and a Y-axis mass block supporting spring 37; the Z-axis portion includes a torsional mass block 41, a first Z-axis symmetrical parallel plate electrode 42, a second Z-axis symmetrical parallel plate electrode 43, a first Z-axis variable-spacing drive electrode 44, a second Z-axis variable-spacing drive electrode 45 and a Y-axis torsional elastic beam 46; the anchor area portion is uniformly defined as the anchor area 5.

[0048] Functionally, micromechanical accelerometer-gyroscopes include:

[0049] A mass assembly is symmetrical about the Y-axis and includes an intermediate mass 1, a torsional mass 41 located within the intermediate mass, and a pair of X-axis masses 21 and a pair of Y-axis masses 31 symmetrically distributed about the center of the intermediate mass. The X-axis mass 21 and the Y-axis mass 31 are connected to the intermediate mass 1 via an X-axis decoupling spring 26 and a Y-axis decoupling spring 36, respectively, and are connected to the anchor area 5 via an X-axis mass support spring 27 and a Y-axis mass support spring 37, respectively. The torsional mass 41 is connected to the intermediate mass 1 via a pair of Y-axis torsional elastic beams 46. The mass assembly is located in the same XY plane. Preferably, the torsional mass 41 has a quasi-cross structure with its four ends pointing to the four quadrants, forming a seesaw structure symmetrical about the Y-axis. The intermediate mass is located on the periphery of the torsional mass and has a similar structure.

[0050] The XYZ axis symmetrical parallel plate capacitor comprises a pair of first X axis symmetrical parallel plate electrodes 22 located at the negative direction of the X axis, a pair of second X axis symmetrical parallel plate electrodes 23 located at the positive direction of the X axis, a pair of first Y axis symmetrical parallel plate electrodes 32 located at the negative direction of the Y axis, a pair of second Y axis symmetrical parallel plate electrodes 33 located at the positive direction of the Y axis, and a pair of first Z axis symmetrical parallel plate electrodes 42 and a pair of second Z axis symmetrical parallel plate electrodes 43 located at the same side of the Z axis; the symmetrical parallel plate electrodes are fixed on the anchor area 5 or the substrate.

[0051] The XYZ axis driver comprises an XY axis variable area comb drive and a Z axis variable interval drive, the XY axis variable area comb drive comprises a first X axis variable area comb electrode 24 located at the negative direction of the X axis, a second X axis variable area comb electrode 25 located at the positive direction of the X axis, a first Y axis variable area comb electrode 34 located at the negative direction of the Y axis, and a second Y axis variable area comb electrode 35 located at the positive direction of the Y axis; the Z axis variable interval drive comprises a pair of first Z axis variable interval drive electrodes 44 and a pair of second Z axis variable interval drive electrodes 45 located at the same side of the Z axis; the fixed electrodes are fixed on the anchor area 5 or the substrate.

[0052] As shown in Figure 1 In the present application, a pair of X axis mass blocks 21 and the intermediate mass block 1 are superimposed to form the resonant equivalent mass in the X axis direction, the X axis mass block support spring 27 and the X axis decoupling spring 26 are connected in parallel to form the resonant equivalent spring in the X axis direction, a pair of Y axis mass blocks 31 and the intermediate mass block 1 are superimposed to form the resonant equivalent mass in the Y axis direction, the Y axis mass block support spring 37 and the Y axis decoupling spring 36 are connected in parallel to form the resonant equivalent spring in the Y axis direction. The X axis decoupling spring 26 has a lower elastic coefficient in the X axis and a larger elastic coefficient in the Y axis and the Z axis; the Y axis decoupling spring 36 has a lower elastic coefficient in the Y axis and a larger elastic coefficient in the X axis and the Z axis; the intermediate mass block 1 and the torsional mass block 41 are the sensitive masses of the Z axis gyroscope, and the torsional elastic beam Y axis torsional elastic beam has a lower torsional elastic coefficient around the Y axis and a larger elastic coefficient on other axes.

[0053] The movable parallel plates of the three-axis symmetrical parallel plate capacitor are respectively fixed with three-axis mass blocks, opposite sign direct current voltages, alternating excitation voltages and carrier voltages are applied on a pair of fixed parallel plate electrodes, and the mass block displacement signals can be obtained by carrier demodulation and low-pass filtering of the signals of the movable parallel plate electrodes; the direct current voltage and the alternating excitation voltage can simultaneously realize resonant driving and amplitude / frequency modulation thereof, and the two working modes are as shown in Figure 5 The amplitude modulation modulates the movable parallel plate displacement caused by acceleration into a resonant amplitude variation, and the frequency modulation modulates the movable parallel plate displacement caused by acceleration into a resonant frequency variation, and in the case of small displacement, the resonant amplitude variation and the resonant frequency variation are approximately linearly related to the displacement.

[0054] The detection of the resonance frequency change is that the mobile parallel plate electrode signal is amplified by the CV circuit, and then is multiplied and demodulated with the carrier voltage signal, and then is multiplied and demodulated with the AC excitation voltage and the AC excitation voltage with a phase difference of 180 degrees, respectively, and is low-pass filtered to obtain two intermediate quantities, and then the two intermediate quantities are divided to obtain a phase quantity, and then the phase quantity is compared with a preset -90 degree phase to obtain a feedback frequency adjustment quantity, which is used to change the AC excitation voltage frequency, that is, the resonance frequency is obtained through the closed loop PLL.

[0055] The force balance accelerometer is that the resonance amplitude and the resonance frequency are compared with the preset amplitude and the preset frequency, respectively, and then the force balance feedback voltage is obtained through the weighted fusion and the controller calculation, which is applied to the variable area comb driver to maintain the mass position constant, and at this time the feedback voltage reflects the acceleration size; the resonance amplitude is determined by the DC voltage, the AC excitation voltage, the mobile parallel plate displacement, the resonance structure stiffness and the quality factor, and the amplitude modulation sensitivity can be improved by increasing the DC voltage, the AC excitation voltage and the quality factor; the resonance frequency is determined by the three-axis resonance structure mass and stiffness, the DC voltage and the angular velocity, and in the force balance control, the resonance frequency deviation weight is set to zero to make the resonance frequency open loop, and at this time the long-term change of the resonance frequency can reflect the temperature change, which can be used for temperature drift compensation; when there is Z-axis angular velocity, the sum of the XY two-axis resonance frequencies will be modulated by the Z angular velocity, which can further work in the Lissajous frequency modulation gyroscope mode; the X-axis and Y-axis angular velocities can be detected in the same way.

[0056] The common three-axis mechanical structure meets the two-axis resonance state in the accelerometer amplitude modulation mode, the difference between the two-axis resonance frequencies can be adjusted to a preset frequency difference value by changing the DC voltage on the symmetrical parallel plate capacitor of the three-axis, the two-axis resonance frequencies can be detected by the PLL closed loop, and the difference and the sum of the two resonance frequencies are calculated respectively to generate a sine signal (the frequency is the difference between the two resonance frequencies), and then the sine signal is multiplied and demodulated with the sum of the two resonance frequencies, and after low-pass filtering, the angular velocity can be obtained.

[0057] In order to express clearly, the three-axis acceleration and the three-axis angular velocity measurement are expressed separately, Figure 2 for XY two-axis acceleration and Z-axis angular velocity detection, Figure 3 for XZ two-axis acceleration and Y-axis angular velocity detection, Figure 4 for YZ two-axis acceleration and X-axis angular velocity detection.

[0058] As Figure 2 and Figure 3As shown, the first X-axis symmetric parallel plate electrode 22 and the movable plate electrode fixedly connected to the left side of the left X-axis mass block form a pair of parallel plate capacitors, and the second X-axis symmetric parallel plate electrode 23 and the movable plate electrode fixedly connected to the right side of the right X-axis mass block form a pair of parallel plate capacitors. The two pairs of parallel plate capacitors are symmetrical structures, that is, the overlapping areas and the initial gaps are the same. When the X-axis equivalent mass produces a motion displacement under the action of the X-axis acceleration, a DC voltage V with opposite signs is applied to the two pairs of parallel plate capacitors. dx and -V dx , resonant voltage A x sin(ω x t) and -A x sin(ω x t) and carrier voltage A cx sin(ω cx t) and -A cx sin(ω cx t), the motion displacement can be obtained through CV circuit and carrier demodulation. Since the X-axis equivalent mass deviates from the initial middle position, the DC voltage and AC excitation voltage on the parallel plate capacitor work together to generate a driving force with the same frequency as the AC excitation voltage. The magnitude of the driving force is related to the displacement, DC voltage and AC excitation voltage. The X-axis structure can be made to resonate through phase-locked loop PLL control, and the X-axis resonance amplitude and resonance frequency can be obtained through secondary demodulation, low-pass filtering and inverse tangent operation. The first X-axis variable area comb electrode 24 and the mobile comb teeth fixedly connected to the right side of the left X-axis mass block form a group of variable area comb teeth drivers, and the second X-axis variable area comb electrode 25 and the mobile comb teeth fixedly connected to the left side of the right X-axis mass block form a group of variable area comb teeth drivers; by comparing the detected X-axis resonance amplitude and resonance frequency with the preset amplitude T x The difference is compared with the frequency, and the sum is multiplied by the preset weight and input into the first PID controller to calculate the force balance feedback voltage. After passing through the push-pull circuit, it is applied to the first X-axis variable area comb electrode 24 and the second X-axis variable area comb electrode 25 to drive the X-axis mass block displacement to remain constant. At this time, the force balance feedback voltage reflects the X-axis acceleration a x .

[0059] like Figure 2 and Figure 4 As shown, the first Y-axis symmetric parallel plate electrode 32 and the movable plate electrode fixedly connected to the lower side of the lower Y-axis mass block form a pair of parallel plate capacitors, and the second Y-axis symmetric parallel plate electrode 33 and the movable plate electrode fixedly connected to the upper side of the upper X-axis mass block form a pair of parallel plate capacitors. The two pairs of parallel plate capacitors are symmetrical structures, that is, the overlapping areas and the initial gaps are the same. When the Y-axis equivalent mass produces a motion displacement under the action of the Y-axis acceleration, a DC voltage V with opposite signs is applied to the two pairs of parallel plate capacitors. dy and -V dy, resonant voltage A y sin(ω y t) and -A y sin(ω y t) and carrier voltage A cy sin(ω cy t) and -A cy sin(ω cy t), the motion displacement can be obtained through CV circuit and carrier demodulation. Since the Y-axis equivalent mass deviates from the initial middle position, the DC voltage and AC excitation voltage on the parallel plate capacitor work together to generate a driving force with the same frequency as the AC excitation voltage. The magnitude of the driving force is related to the displacement, DC voltage and AC excitation voltage. The Y-axis structure can be made to resonate through phase-locked loop PLL control, and the Y-axis resonance amplitude and resonance frequency can be obtained through secondary demodulation, low-pass filtering and inverse tangent operation. The first Y-axis variable area comb tooth electrode 34 and the mobile comb teeth fixedly connected to the upper side of the lower Y-axis mass block form a group of variable area comb tooth drivers, and the second Y-axis variable area comb tooth electrode 35 and the mobile comb teeth fixedly connected to the lower side of the upper Y-axis mass block form a group of variable area comb tooth drivers; by comparing the detected Y-axis resonance amplitude and resonance frequency with the preset amplitude T y The difference is compared with the frequency, multiplied by the preset weight, and then summed and input into the second PID controller to calculate the force balance feedback voltage. After passing through the push-pull circuit, it is applied to the first Y-axis variable area comb electrode 34 and the second Y-axis variable area comb electrode 35 to drive the Y-axis mass block displacement to remain constant. At this time, the force balance feedback voltage reflects the Y-axis acceleration a y .

[0060] like Figure 3 and Figure 4 As shown, the first Z-axis symmetric parallel plate electrode 42 and the movable plate electrode fixedly connected to the left bottom of the torsional mass 41 form a pair of parallel plate capacitors, and the second Z-axis symmetric parallel plate electrode 43 and the movable plate electrode fixedly connected to the right bottom of the torsional mass 41 form a pair of parallel plate capacitors. The two pairs of parallel plate capacitors are symmetrical structures, that is, the overlapping areas and the initial gaps are the same. When the torsional mass generates a motion displacement under the action of the Z-axis acceleration, a DC voltage V with opposite signs is applied to the two pairs of parallel plate capacitors. dz and -V dz , resonant voltage A z sin(ω z t) and -A y sin(ω y t) and carrier voltage A cz sin(ω cz t) and -A cz sin(ω czt), the motion displacement can be obtained through CV circuit and carrier demodulation. Since the torsional mass deviates from the initial middle position, the DC voltage and resonant voltage on the parallel plate capacitor work together to generate a driving force with the same frequency as the resonant voltage. The magnitude of the driving force is related to the displacement, DC voltage and AC excitation voltage. The Z-axis structure can be made to resonate through phase-locked loop PLL control, and the Z-axis resonant amplitude and resonant frequency can be obtained through secondary demodulation, low-pass filtering and inverse tangent operation. The first Z-axis variable spacing drive electrode 44 and the mobile plate electrode fixedly connected to the left bottom of the torsional mass block form a group of variable spacing drivers, and the second Z-axis variable spacing drive electrode 45 and the mobile plate electrode fixedly connected to the right bottom of the torsional mass block form a group of variable spacing drivers; by comparing the detected Z-axis resonant amplitude and resonant frequency with the preset amplitude T z The difference is compared with the frequency, multiplied by the preset weight, and then summed and input into the third PID controller and PWM modulator to calculate the force balance feedback voltage. After passing through the push-pull circuit, it is applied to the first Z-axis variable spacing drive electrode 44 and the second Z-axis variable spacing drive electrode 45 to drive the torsion mass block to remain constant. At this time, the force balance feedback voltage reflects the Z-axis acceleration a z .

[0061] As a preferred embodiment, the preset weight of the resonance frequency deviation can be set to 0, and the preset weight of the resonance amplitude deviation is set to 1. At this time, the accelerometer operates in amplitude modulation mode;

[0062] like Figure 2 As shown, in the above-mentioned amplitude modulation accelerometer working mode, by summing the detected X-axis and Y-axis resonant frequencies respectively (ω x +ω y ) and the difference (ω x -ω y ), a frequency of (ω x -ω y ) of the sinusoidal signal sin(ω x t-ω y t), use the sinusoidal signal to compare the X-axis and Y-axis frequencies (ω x +ω y ) is multiplied, demodulated, and low-pass filtered to obtain the Z-axis angular velocity Ω. z .

[0063] like Figure 3 As shown, in the above-mentioned amplitude modulation accelerometer working mode, by summing the detected X-axis and Z-axis resonant frequencies (ω x +ω z ) and the difference (ω x -ω z ), a frequency of (ω x -ω z) of the sinusoidal signal sin(ω x t-ω y t), use this sinusoidal signal to calculate the X-axis and Z-axis frequencies (ω x +ω z ) is multiplied, demodulated, and low-pass filtered to obtain the Y-axis angular velocity Ω. y .

[0064] like Figure 4 As shown, in the above-mentioned amplitude modulation accelerometer working mode, by summing the detected Y-axis and Z-axis resonant frequencies respectively (ω y +ω z ) and the difference (ω y -ω z ), a frequency of (ω y -ω z ) of the sinusoidal signal sin(ω y t-ω z t), use the sinusoidal signal to calculate the Y-axis and Z-axis frequencies (ω y +ω z ) is multiplied, demodulated, and low-pass filtered to obtain the X-axis angular velocity Ω. x .

[0065] Those skilled in the art should understand that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A highly integrated micromechanical accelerometer-gyroscope, characterized in that: An XYZ three-degree-of-freedom mass-spring-damper system is used as a common sensitive structure, including: A mass block assembly is symmetrical about the Y axis, comprising an intermediate mass block (1), a torsion mass block (41) located inside the intermediate mass block, and a pair of X-axis mass blocks (21) and a pair of Y-axis mass blocks (31) symmetrically distributed around the intermediate mass block about the center; the X-axis mass block (21) and the Y-axis mass block (31) are connected to the intermediate mass block (1) via a Y-axis decoupling spring (36) and an X-axis decoupling spring (26), respectively, and are connected to the anchor area via an X-axis mass block support spring (27) and a Y-axis mass block support spring (37), respectively; the torsion mass block (41) is connected to the intermediate mass block (1) via a pair of Y-axis torsion elastic beams (46); and the mass block assembly is located in the same XY plane; An XYZ axisymmetric parallel plate capacitor comprises a pair of first X axisymmetric parallel plate electrodes (22) located in the negative direction of the X axis, a pair of second X axisymmetric parallel plate electrodes (23) located in the positive direction of the X axis, a pair of first Y axisymmetric parallel plate electrodes (32) located in the negative direction of the Y axis, a pair of second Y axisymmetric parallel plate electrodes (33) located in the positive direction of the Y axis, and a pair of first Z axisymmetric parallel plate electrodes (42) and a pair of second Z axisymmetric parallel plate electrodes (43) located in the negative direction of the Z axis; An XYZ-axis driver comprises an XY-axis variable-area comb driver and a Z-axis variable-spacing driver, wherein the XY-axis variable-area comb driver comprises a first X-axis variable-area comb electrode (24) located in the negative direction of the X-axis, a second X-axis variable-area comb electrode (25) located in the positive direction of the X-axis, a first Y-axis variable-area comb electrode (34) located in the negative direction of the Y-axis, and a second Y-axis variable-area comb electrode (35) located in the positive direction of the Y-axis; and the Z-axis variable-spacing driver comprises a pair of first Z-axis variable-spacing driving electrodes (44) and a pair of second Z-axis variable-spacing driving electrodes (45) located in the negative direction of the Z-axis. The first X-axis symmetric parallel plate electrode (22) and the second X-axis symmetric parallel plate electrode (23) are fixed in the anchor area and are symmetrically distributed about the Y axis; A first X-axis variable-area comb-tooth electrode (24) and a second X-axis variable-area comb-tooth electrode (25) are fixed in the anchor area and are symmetrically distributed about the Y axis; The first X-axis symmetrical parallel plate electrode (22) and a movable parallel plate electrode installed on the left side of an X-axis mass block (21) form a parallel plate capacitor, and the first X-axis variable area comb electrode (24) and the movable comb teeth on the right side of the same X-axis mass block (21) form a comb capacitor; The second X-axis symmetrical parallel plate electrode (23) and the movable parallel plate electrode installed on the right side of another X-axis mass block (21) form a parallel plate capacitor, and the second X-axis variable area comb electrode (25) and the movable comb teeth on the left side of the same X-axis mass block (21) form a comb capacitance.

2. The highly integrated micromechanical accelerometer-gyroscope according to claim 1, characterized in that: The first Y-axis symmetric parallel plate electrode (32) and the second Y-axis symmetric parallel plate electrode (33) are fixed in the anchor area and are symmetrically distributed about the X-axis; A first Y-axis variable-area comb-tooth electrode (34) and a second Y-axis variable-area comb-tooth electrode (35) are fixed in the anchor region and are symmetrically distributed about the X-axis; The first Y-axis symmetrical parallel plate electrode (32) and a movable parallel plate electrode installed on the lower side of a Y-axis mass block (31) form a parallel plate capacitor, and the first Y-axis variable area comb electrode (34) and the movable comb teeth on the upper side of the same Y-axis mass block (31) form a comb capacitance; The second Y-axis symmetrical parallel plate electrode (33) and the movable parallel plate electrode installed on the upper side of another Y-axis mass block (31) form a parallel plate capacitor, and the second Y-axis variable area comb electrode (35) and the movable comb teeth on the lower side of the same Y-axis mass block (31) form a comb capacitance.

3. The highly integrated micromechanical accelerometer-gyroscope according to claim 1, characterized in that: The pair of first Z-axis symmetric parallel plate electrodes (42) and the pair of second Z-axis symmetric parallel plate electrodes (43) are fixed on a substrate parallel to the mass block assembly, with a gap between them and the torsion mass block (41); wherein the pair of first Z-axis symmetric parallel plate electrodes (42) are symmetric about the X-axis, the pair of second Z-axis symmetric parallel plate electrodes (43) are symmetric about the X-axis, and the pair of first Z-axis symmetric parallel plate electrodes (42) and the pair of second Z-axis symmetric parallel plate electrodes (43) are symmetric about the Y-axis; A pair of first Z-axis symmetrical parallel plate electrodes (42) and a movable parallel plate electrode mounted on the top or bottom of the torsion mass (41) form a pair of parallel plate capacitors; A pair of second Z-axis symmetrical parallel plate electrodes (43) and a movable parallel plate electrode mounted on the top or bottom of the torsion mass (41) form a pair of parallel plate capacitors; The two pairs of parallel plate capacitors are initially in a centrosymmetrical structure.

4. The highly integrated micromechanical accelerometer-gyroscope according to claim 1, characterized in that: The pair of first Z-axis variable-spacing driving electrodes (44) and the pair of second Z-axis variable-spacing driving electrodes (45) are fixed on a substrate parallel to the mass block assembly, with a gap between them and the torsion mass block (41); wherein the pair of first Z-axis variable-spacing driving electrodes (44) are symmetrical about the X-axis, the pair of second Z-axis variable-spacing driving electrodes (45) are symmetrical about the X-axis, and the pair of first Z-axis variable-spacing driving electrodes (44) and the pair of second Z-axis variable-spacing driving electrodes (45) are symmetrical about the Y-axis; A pair of first Z-axis variable pitch driving electrodes (44) and a movable parallel plate electrode mounted on the top or bottom of the torsion mass block (41) form a pair of Z-axis variable pitch drivers; A pair of second Z-axis variable pitch driving electrodes (45) and a movable parallel plate electrode mounted on the top or bottom of the torsion mass block (41) form a pair of Z-axis variable pitch drivers; The two pairs of variable-pitch drivers are centrally symmetrical in structure.

5. The highly integrated micromechanical accelerometer-gyroscope according to claim 1, characterized in that: The X-axis decoupling spring (26) has a smaller elastic coefficient in the X-axis and a larger elastic coefficient in the Y-axis and the Z-axis; the Y-axis decoupling spring (36) has a smaller elastic coefficient in the Y-axis and a larger elastic coefficient in the X-axis and the Z-axis; the Y-axis torsional elastic beam (46) has a smaller torsional elastic coefficient around the Y-axis and a larger torsional elastic coefficient around the X-axis and the Z-axis.

6. The highly integrated micromachined accelerometer-gyroscope according to claim 1, characterized in that: The torsion mass block (41) is in a non-centrosymmetrical seesaw structure.

7. The highly integrated micromachined accelerometer-gyroscope according to claim 1, characterized in that: The detection method of single-axis acceleration includes: Apply a DC voltage V with opposite signs to two pairs of symmetrical parallel plate electrodes on the target axis. di and -V di , resonant voltage A i sin(ω i t) and -A i sin(ω i t), carrier voltage A ci sin(ω ci t) and -A ci sin(ω ci t), obtain the signal of the intermediate mass block and demodulate it to obtain the target axis resonance amplitude and resonance frequency; where A i 、ω i Represents the resonant voltage amplitude and frequency, A ci 、ω ci Indicates the carrier voltage amplitude and frequency, t indicates time, and the subscript i is any one of X, Y, and Z. When i = X, it corresponds to detecting the acceleration of the X axis, when i = Y, it corresponds to detecting the acceleration of the Y axis, and when i = Z, it corresponds to detecting the acceleration of the Z axis. The detected target axis resonance amplitude and resonance frequency are deviated from the preset amplitude and frequency, and the difference is multiplied by the preset weight of the resonance amplitude deviation and the preset weight of the resonance frequency deviation respectively, and then the sum is input into the PID controller to calculate the force balance feedback voltage. After passing through the push-pull circuit, it is applied to the target axis driver to drive the corresponding mass block to keep the displacement constant. At this time, the force balance feedback voltage reflects the acceleration of the target axis.

8. The highly integrated micromechanical accelerometer-gyroscope according to claim 7, characterized in that: The detection method of single-axis angular velocity includes: When the target axis generates angular velocity, the single-axis acceleration detection method is used to obtain the resonant frequencies of the two single axes other than the target axis; The sum and difference of the resonant frequencies of the two single axes other than the target axis are obtained respectively; A sinusoidal signal with a frequency equal to the difference between the resonant frequencies is generated, and the sum of the resonant frequencies is multiplied, demodulated, and low-pass filtered using the sinusoidal signal to obtain the target shaft angular velocity.

9. The highly integrated micromechanical accelerometer-gyroscope according to claim 8, characterized in that: When detecting angular velocity, the two single axes other than the target axis operate in the amplitude modulation accelerometer operating mode, that is, the preset weight of the resonance amplitude deviation is 1, and the preset weight of the resonance frequency deviation is set to 0.

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