Holosymmetric four-mass MEMS gyroscope

Abstract

The invention discloses a holosymmetric four-mass MEMS gyroscope which comprises four sensitive mass block coupling structures which are arranged in a central symmetry manner, and four first U-shaped beams, four n-shaped beams and a cross-shaped coupling structure which are arranged in a central symmetry manner and are connected with the four sensitive mass block coupling structures, compared with the prior art, the four sensitive mass block coupling structures are designed compactly and symmetrically, so that the sensitivity can be effectively improved, and thermally induced drift can be effectively reduced. The driving mode and the working mode are separated through the specific coupling mechanism, so that frequency coupling is avoided, and environmental vibration interference is reduced. And meanwhile, the symmetry of the structure is beneficial to uniform distribution of thermal stress or mechanical stress, so that zero drift caused by temperature change is inhibited.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of micro-electro-mechanical system (MEMS) gyroscope, and particularly relates to a full-symmetry four-mass MEMS gyroscope with enhanced common-mode rejection capability and modal decoupling characteristics. BACKGROUND

[0002] MEMS gyroscope is a key device for measuring rotational angular rate, and occupies a core position in the fields of motion detection, inertial navigation and guidance control, and has irreplaceable application value in high-end equipment such as aerospace, intelligent robots and high-precision guidance weapons. With the support of micro-electro-mechanical system (MEMS) technology, such gyroscope has the advantages of compact size, low cost, low energy consumption, long service life, multi-functional integration and easy scale production.

[0003] In the existing symmetrical gyroscope structure: ring configuration, the sensitive mass of this structure is too small; double-mass configuration has poor symmetry, poor common-mode error rejection effect, and large coupling; eight-mass configuration is complex, and the effective area utilization rate of the chip is insufficient.

[0004] It is still a technical problem to realize a compact gyroscope configuration in a very small chip size, to realize efficient decoupling of driving / detection modes to suppress common-mode interference, and to maintain high structural symmetry to resist thermal drift. For example, the four-mass MEMS structure in the prior art has the problems of easy coupling between driving and detection modes, disturbance to common-mode vibration, and thermal stress sensitivity caused by uneven anchor point position. SUMMARY

[0005] The purpose of the present application is to provide a full-symmetry four-mass MEMS gyroscope, which solves the problems of easy coupling between driving and detection modes, disturbance to common-mode vibration, and performance indeterminacy caused by thermal stress sensitivity of the anchor point in the prior art MEMS gyroscope through the structural design of Π-coupled beam and cross beam.

[0006] The technical solution for achieving the purpose of the present application is: a full-symmetry four-mass MEMS gyroscope, comprising four symmetrically arranged sensitive mass block coupling structures, and four first U-shaped beams, four Π-shaped beams, and a cross-shaped coupling structure symmetrically arranged and connected to the four sensitive mass block coupling structures; the first U-shaped beam is connected to the trapezoidal coupling structure in the sensitive mass block coupling structure, and is used to absorb the force in the direction of the angle bisector of the entire structure of the vertical gyroscope; the Π-shaped beam is used to make the sensitive mass blocks in the adjacent sensitive mass block coupling structures move in opposite directions, and the cross-shaped coupling structure is used to make the sensitive mass blocks in the opposite sensitive mass block coupling structures move in opposite directions.

[0007] Further, each sensitive mass coupling structure comprises: a driving capacitor frame, a sensitive mass, a driving and detecting capacitor frame, two L-shaped coupling structures, six J-shaped beams, four fixed anchors, eight second U-shaped beams, and a trapezoidal coupling structure.

[0008] The sensitive mass is in a right-angled triangle structure, and the right-angled point is the coordinate origin. The direction of the symmetry axis of the sensitive mass is defined as the Y axis and the outward direction from the center is positive. The direction perpendicular to the Y axis is the X axis and the outward direction from the center is positive.

[0009] The adjacent sensitive masses are connected by Π-shaped beams. The Π-shaped beams are used to make the sensitive masses arranged along the Y axis move in the opposite direction of the sensitive masses arranged along the X axis.

[0010] The two L-shaped coupling structures fixed on the periphery of the driving capacitor frame are connected. Two groups of J-shaped beams are arranged on both sides of the driving capacitor frame in an axisymmetric manner. Each group has two J-shaped beams arranged along the X axis direction, which are connected by L-shaped fixed anchors. The J-shaped beams are used to make the sensitive mass vibrate freely in the Y axis direction and constrain and absorb the motion in the X axis direction.

[0011] Two J-shaped beams are arranged on one side of the driving capacitor frame close to the center of the structure in an axisymmetric manner along the Y axis direction. The J-shaped beams are fixedly connected with the sensitive mass. The J-shaped beams are used to realize the transmission of the force in the X axis direction and the absorption of the motion in the Y axis direction.

[0012] The sensitive mass is fixedly connected with the trapezoidal coupling structure on one side close to the center of the structure. The trapezoidal coupling structure is used to transmit the force in the Y axis direction and suppress the force in the X axis direction. The adjacent trapezoidal coupling structures are connected by first U-shaped beams.

[0013] The trapezoidal coupling structure is connected with the directional end of the cross-shaped coupling structure on one side close to the center of the structure. The cross-shaped coupling structure is used to transmit the force in the Y axis direction.

[0014] Four fixed anchors are arranged at the four corners of the driving and detecting capacitor frame. One end of the second U-shaped beam is fixedly connected with the fixed anchor, and the other end is fixedly connected with the sensitive mass.

[0015] Further, eight second U-shaped beams are arranged around the driving and detecting capacitor frame in an axisymmetric manner, and each fixed anchor is connected with two second U-shaped beams. The second U-shaped beams are used to make the driving capacitor frame move with the sensitive mass.

[0016] Further, the gyroscope has four working modes.

[0017] In the first working mode, among the four sensitive masses, two opposite sensitive masses expand outward along the respective Y axis direction, and the other two opposite sensitive masses contract inward along the respective Y axis direction. The driving and detecting capacitor frame remains stationary.

[0018] In the second working mode, the diagonal sensitive mass blocks are reversely moved to drive the detection frame to move;

[0019] In the third working mode, the four sensitive mass blocks are expanded outward along the Y-axis direction of the local coordinate system of the coupling structure of the respective sensitive mass block, and the driving detection capacitance frame remains unchanged.

[0020] In the fourth working mode, the four axisymmetrically arranged sensitive mass blocks rotate counterclockwise or clockwise; the four axisymmetrically arranged driving capacitance frames remain unchanged.

[0021] Further, the Coriolis force acting on the sensitive mass block in the first working mode can excite the vibration of the second working mode; the Coriolis force acting on the sensitive mass block in the third working mode can excite the vibration of the fourth working mode.

[0022] Further, the driving capacitance frame arranged in the axisymmetric manner is arranged with comb electrodes; the driving detection capacitance frame is arranged with parallel plate electrodes.

[0023] Further, the sensitive mass block is further provided with orthogonal electrodes to compensate for the comb electrode error caused by the etching error in the process of manufacturing the driving capacitance frame.

[0024] Further, one end of the L-shaped coupling structure is a double-folded beam, and the other end is a J-shaped beam; the L-shaped coupling structure reduces the stiffness of the driving capacitance frame along the Y-axis direction, so that the sensitive mass block freely vibrates along the Y-axis direction; and the L-shaped coupling structure increases the stiffness of the driving capacitance frame along the X-axis direction to constrain the movement along the X-axis direction.

[0025] Further, the cross-shaped coupling structure is provided with an anchor point in the middle for increasing the stability of the cross-shaped coupling structure.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] 1. Enhanced common mode rejection capability: through the symmetrical arrangement of the four sensitive mass blocks and the cooperative action of the Π-shaped coupling beam, the present application realizes a "heartbeat" driving mode. In this mode, the same direction movement caused by the external environment vibration is effectively cancelled, thereby significantly improving the signal-to-noise ratio and anti-interference capability of the gyroscope.

[0028] 2. Efficient modal decoupling: the L-shaped decoupling elastic structure effectively isolates the driving movement from the detection movement caused by the Coriolis force in the mechanical aspect, avoids the frequency coupling and energy crosstalk between the two modes, and thereby improves the measurement accuracy and linearity.

[0029] 3. Excellent temperature stability: the overall structure full symmetry ensures that when the ambient temperature changes, the anchor point full symmetry arrangement produces thermal stress that can be evenly distributed on the substrate, minimizing the zero point drift caused by local deformation, significantly improving the temperature performance of the gyroscope. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Figure 1 is a schematic diagram of a full-symmetry four-mass MEMS gyroscope structure according to the present application;

[0031] Figure 2 Figure 2 is a detailed view of other structural positions of the full-symmetry four-mass MEMS gyroscope structure according to the present application, wherein Figure 2 a is a detailed view of the J-beam position, Figure 2 b is a detailed view of the small anchor position, Figure 2 c is a detailed view of the anchor position, Figure 2 d is a detailed view of the second U-beam position, Figure 2 e is a detailed view of the trapezoidal coupling structure position;

[0032] Figure 3 Figure 3 is a schematic diagram of a quarter structure according to the present application;

[0033] Figure 4 Figure 4 is a schematic diagram of a Π-beam structure according to the present application;

[0034] Figure 5 Figure 5 is a schematic diagram of an L-coupling structure according to the present application;

[0035] Figure 6 Figure 6 is a schematic diagram of a cross-coupling structure according to the present application;

[0036] Figure 7 Figure 7 is a schematic diagram of a J-beam structure according to the present application; trapezoidal coupling structure

[0037] Figure 8 Figure 8 is a schematic diagram of a trapezoidal coupling structure according to the present application;

[0038] Figure 9 Figure 9 is a first working mode displacement nephogram of the full-symmetry four-mass MEMS gyroscope structure according to the present application, with the motion direction and force direction of each part of the mass indicated;

[0039] Figure 10 Figure 10 is a second working mode displacement nephogram of the full-symmetry four-mass MEMS gyroscope structure according to the present application, with the motion direction of each part of the mass indicated;

[0040] Figure 11 Figure 11 is a third working mode displacement nephogram of the full-symmetry four-mass MEMS gyroscope structure according to the present application, with the motion direction of each part of the mass indicated;

[0041] Figure 12The fourth working mode displacement nephogram of the full symmetry type four-mass MEMS gyroscope structure and the motion direction of each part mass;

[0042] Figure 13 The full symmetry type four-mass MEMS gyroscope of the present application;

[0043] Figure 14 The partial enlargement of the full symmetry type four-mass MEMS gyroscope structure and the position diagram of the capacitive electrode arrangement;

[0044] Figure 15 The full symmetry type four-mass MEMS gyroscope structure orthogonal electrode arrangement detail diagram;

[0045] Figure 16 The full symmetry type four-mass MEMS gyroscope structure detection electrode arrangement detail diagram; DETAILED DESCRIPTION

[0046] The terms used in the present application are only for the purpose of illustrating the embodiments of the present application, and are not intended to limit the present application. The following will be described in detail with reference to the accompanying drawings. Figures 1-16 Some embodiments of the present application are described in detail.

[0047] For the convenience of definition, the embodiment establishes an overall rectangular coordinate system and a local rectangular coordinate system. The overall rectangular coordinate system is established with the center of the full symmetry type four-mass MEMS gyroscope as the origin, the A-axis is established with the center outward as the positive direction, and the B-axis is established with the center outward as the positive direction.

[0048] The local rectangular coordinate system is a right triangle structure of the sensitive mass block 201, and the right angle point is the coordinate origin. The symmetric axis direction of the sensitive mass block 201 is defined as the Y-axis and the center outward as the positive direction. The direction perpendicular to the Y-axis is the X-axis and the center outward as the positive direction.

[0049] In combination with Figure 1 Figure 2 Figure 3 Because the present application is a full symmetry type four-mass gyroscope, it includes centrally symmetric arrangement of 4 first U-shaped beams 001, 4 Π-shaped beams 401, 4 L-shaped fixed anchor points 601, 1 cross-shaped coupling structure 701, 4 first fixed anchor points 901, and 4 sensitive mass block coupling structures.

[0050] Each sensitive mass block coupling structure includes 1 driving capacitive frame 101, 1 sensitive mass block 201, 1 driving and detection capacitive frame 301, 2 L-shaped coupling structures 501, 6 J-shaped beams 801, 4 fixed anchor points 1001, 8 second U-shaped beams 1101, and 1 trapezoidal coupling structure 1201.

[0051] The adjacent sensitive mass blocks 201 are connected through the Π-shaped sensitive mass coupling beam 401. Two L-shaped coupling structures 501 are arranged on the side of the driving capacitor frame 101 away from the center of the structure along the Y-axis direction and are connected; the L-shaped coupling structure 501 makes the driving capacitor frame 101 have lower stiffness along the Y-axis direction, thereby allowing the sensitive mass block 101 to freely vibrate along the Y-axis direction; and the L-shaped coupling structure 501 has higher stiffness along the X-axis direction, thereby effectively restraining and absorbing unnecessary horizontal motion.

[0052] Two groups of two J-shaped beams 801 arranged along the X-axis direction are arranged on both sides of the driving capacitor frame 101 in an axisymmetric manner and are connected through the L-shaped fixed anchor point 601; the J-shaped beam 801 arranged along the X-axis direction is used to realize transmission of Y-axis direction motion and absorption of X-axis direction motion perpendicular to the Y-axis direction, thereby achieving anisotropic stiffness through structural design. When the driving capacitor frame 101 transmits horizontal force to the J-shaped beam 801, the J-shaped beam 801 does not move; when the driving capacitor frame 101 transmits vertical force to the J-shaped beam 801, the J-shaped beam 801 transmits Y-axis direction force;

[0053] Two J-shaped beams 801 arranged along the Y-axis direction are arranged on the side of the driving capacitor frame 101 close to the center of the structure in an axisymmetric manner, and the J-shaped beam 801 is connected with the sensitive mass block 201; through the structural design that the J-shaped beam 801 arranged along the Y-axis direction is connected with the sensitive mass block 201, transmission of X-axis direction motion and absorption of Y-axis direction motion perpendicular to the X-axis direction are realized; when the driving capacitor frame 101 transmits X-axis direction force to the two J-shaped beams 801 arranged along the Y-axis direction in an axisymmetric manner, the two J-shaped beams 801 transmit X-axis direction force to the sensitive mass block 201; when the driving capacitor frame 101 transmits Y-axis direction force to the two J-shaped beams 801 arranged along the Y-axis direction in an axisymmetric manner, the two J-shaped beams 801 arranged along the Y-axis direction do not transmit vertical force to the sensitive mass block 201;

[0054] One Y-axis direction sensitive mass block 201 and one X-axis direction sensitive mass block 201 are connected through the arrangement of the Π-shaped beam 401; the structure of the Y-axis direction sensitive mass block 201 is configured to force the X-axis direction sensitive mass block 201 to perform reverse motion in the driving mode;

[0055] The sensitive mass block 201 is fixedly connected with the trapezoidal coupling structure 1201 on the side close to the center of the structure; when the sensitive mass block 201 transmits X-axis direction force to the trapezoidal coupling structure 1201, the trapezoidal coupling structure 1201 is static; when the sensitive mass block 201 transmits Y-axis direction force to the trapezoidal coupling structure 1201, the trapezoidal coupling structure 1201 transmits Y-axis direction force to the cross-shaped coupling joint 701; the trapezoidal coupling structure 1201 transmits Y-axis direction force and suppresses X-axis direction force;

[0056] One Y-axis direction arranged trapezoidal coupling structure 1201 and one X-axis direction arranged trapezoidal coupling structure 1201 are connected by a first U-shaped beam 001; the U-shaped beam is arranged in the Y-axis direction or the X-axis direction, realizing the transmission of the motion in a specific direction and the absorption of the motion in the orthogonal direction;

[0057] The trapezoidal coupling structure 1201 is connected to the positive Y-direction end of the cross-shaped coupling structure 701 near the center of the structure; when the trapezoidal coupling structure 1201 transmits the Y-axis direction force to the cross-shaped coupling structure 701, the cross-shaped coupling structure 701 transmits the Y-axis direction force;

[0058] Four fixed anchor points 1001 are arranged at the four corners of the drive detection capacitor frame 301; one end of a second U-shaped beam 1101 is fixedly connected to the fixed anchor point 1001, and the other end is fixedly connected to the sensitive mass block 201. Among them, eight second U-shaped beams 1101 are symmetrically arranged around the four corners of the drive detection capacitor frame 301, and each fixed anchor point 1001 is connected to two second U-shaped beams 1101. When the sensitive mass block 201 transmits the Y-axis direction force to the drive detection capacitor frame 301 along the Y-axis direction, four second U-shaped beams 1101 transmit the Y-axis direction force; when the drive detection capacitor frame 301 moves horizontally, four U-shaped beams 1101 transmit the X-axis direction force.

[0059] The full-symmetry four-mass MEMS gyroscope has Figure 9 The resonance mode shown in the figure is the first working mode, Figure 10 The resonance mode shown in the figure is the second working mode, Figure 11 The resonance mode shown in the figure is the third working mode, Figure 12 The resonance mode shown in the figure is the fourth working mode, Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 The modal simulation nephogram of Example 1, the color legend gradually changes from blue to red, indicating that the deformation motion gradually increases

[0060] Under the first working mode, combined with Figure 9As shown, in the four sensitive mass coupling structures, two drive capacitors 101 arranged along the B-axis direction move away from each other in the A-axis direction; in turn, two sensitive masses 201 move away from each other in the A-axis direction; two drive capacitors 101 arranged along the A-axis direction move towards each other in the B-axis direction; in turn, two sensitive masses 201 move towards each other in the B-axis direction; four drive and detection capacitors 301 arranged in an axial symmetry keep unchanged; the first working mode mainly shows the contraction of two sensitive masses along the B-axis direction and the expansion of two sensitive masses along the A-axis direction, and the positions of four drive and detection capacitors keep unchanged; it is called a "heartbeat" drive mode, which is the selected working drive mode of the application. In this mode, four sensitive masses 201 synchronously expand or contract along the respective Y-axis direction, while the drive and detection capacitors 301 keep stationary.

[0061] In the second working mode, in combination with Figure 10 As shown, the four sensitive mass coupling structures are divided into two groups along the 45° line in the middle of the A-axis or B-axis, and the adjacent two sensitive masses 201 in each group move towards each other along the vertical direction of the 45° line, while the adjacent sensitive masses 201 in different groups move away from each other; in turn, the drive and detection capacitors 301 also move; it is called a detection mode. In this mode, the diagonal sensitive masses move in opposite directions, and the drive and detection capacitors also move.

[0062] In the third working mode, in combination with Figure 11 As shown, in the four sensitive mass coupling structures, the drive capacitors 101 move along the positive direction of the Y-axis in the respective local coordinate system, in turn, the adjacent drive capacitors 101 move away from each other; in turn, the sensitive masses 201 move along the positive direction of the Y-axis in the respective local coordinate system; the four drive and detection capacitors 301 arranged in an axial symmetry keep unchanged; the working mode mainly shows the in-plane expansion of the structure, and four sensitive masses 201 expand outward along the Y-axis direction of the local coordinate system of the respective sensitive mass coupling structure, while the drive and detection capacitors 301 keep unchanged; it is called a stray drive mode.

[0063] In the fourth working mode, in combination with Figure 12 As shown, the four drive capacitors 101 arranged in an axial symmetry keep unchanged; four sensitive masses 201 move in the clockwise or counterclockwise direction, in turn, the drive and detection capacitors 301 move in the clockwise or counterclockwise direction; the fourth working mode mainly shows the counterclockwise or clockwise rotation of the four sensitive masses 201 arranged in an axial symmetry; it is called a torsion mode.

[0064] In the first operating mode, when the gyroscope is driven at the first operating mode (the resonant frequency ω of the first operating mode), if there is an input angular velocity Ω perpendicular to the chip plane, the sensitive mass block 201 will be subjected to a Coriolis force. The sensitive mass block vibrating along the A-axis is subjected to a Coriolis force F along the B-axis. C1 (t) is:

[0065] F C1 (t)=-2mΩ×v1(t)

[0066] In the formula, m is the mass of the sensitive mass block, the rotational angular rate of the gyroscope relative to the inertial frame is Ω, the vibration velocity of the sensitive mass block vibrating in the A-axis direction is v1(t)=Rωsin(ωt), R is the vibration amplitude of the sensitive mass block vibrating in the A-axis direction, ω is the resonant frequency of the first working mode, and t is the time variable;

[0067] The sensitive mass block vibrating along the B-axis is subjected to a Coriolis force F along the A-axis. C2 (t) is:

[0068] F C2 (t)=-2mΩ×v2(t)

[0069] In the formula, m is the mass of the sensitive mass block, the rotational angular rate of the gyroscope relative to the inertial frame is Ω, the vibration velocity of the sensitive mass block vibrating in the B-axis direction is v2(t)=Hωsin(ωt), H is the vibration amplitude of the sensitive mass block vibrating in the B-axis direction, ω is the resonant frequency of the first working mode, and t is the time variable;

[0070] These Coriolis forces will excite the vibration of the second working mode.

[0071] In the first operating mode, the sensitive mass 201, arranged along the positive A-axis, receives as follows: Figure 11 Coriolis force F C1 (t); Sensitive mass 201, arranged along the positive B-axis, receives as follows Figure 11 Coriolis force F C2 (t); Sensitive mass 201, arranged along the negative A-axis, receives as follows Figure 11 Coriolis force - F C1 (t); Sensitive mass 201, arranged along the negative B-axis, receives as follows Figure 11 Coriolis force - F C2 (t); the Coriolis force F C1 (t), F C2 (t), -F C1 (t), -F C2 (t) and Figure 12The second working mode motion direction is consistent with the second working mode vibration, and the second working mode vibration is excited. Therefore, when the full-symmetry four-mass gyroscope works in the first working mode, the Coriolis force generated by the angular rate Omega input excites the second working mode vibration. The angular rate Omega can be calculated by detecting the vibration amplitude of the second working mode and the formula (prior art) of the amplitude and the angular rate Omega.

[0072] The full-symmetry four-mass MEMS gyroscope is arranged with comb electrodes 13 in the four-axially symmetric driving capacitor frames 101; four driving and detecting capacitor frames 301 are arranged with parallel plate electrodes 15 in the four-axially symmetric sensing masses 201, as shown in Figure 13 ;

[0073] The comb electrodes in the driving frame 101 are enlarged, as shown in Figure 14 ;

[0074] The capacitance C1(t) of the comb electrodes is:

[0075]

[0076] Wherein, N is the number of combs, the vacuum dielectric constant ε = 8.85 × 10 -12 F / m, h is the gyroscope structure thickness, l is the comb overlap length, h(l+Δx1(t)) is the electrode and gyroscope structure overlap area, d1 is the overlap gap of the comb electrode and the gyroscope structure comb, the comb overlap length change Δx1(t) = R1cos(ωt); R1 is the amplitude of the external decoupling mass arranged with the comb electrode, ω is the angular frequency of the first working mode, and t is the time variable;

[0077] The parallel plate electrodes in the sensing mass amplification part are enlarged, as shown in Figure 15 ;

[0078] The capacitance C2(t) of the parallel plate electrodes is:

[0079]

[0080] Wherein, the order n of Taylor expansion = ∞, the vacuum dielectric constant ε = 8.85 × 10 -12 F / m, A is the total overlap area of the parallel plate electrode and the gyroscope structure, d2 is the gap between the parallel plate electrode and the gyroscope structure, the gap change Δx2(t) = R2cos(ωt), R2 is the amplitude of the internal decoupling mass arranged with the parallel plate electrode, ω is the angular frequency of the first working mode, and t is the time.

[0081] When the two capacitive electrodes are used as detection electrodes, the capacitance varies with the amplitude of the discharge, and the amplitude can be calculated by the current size to identify the vibration amplitude R of the first working mode sensitive mass block and the vibration amplitude H of the second working mode sensitive mass block. The current i1 generated by the comb electrode and the current i2 generated by the parallel plate electrode are:

[0082]

[0083] In the formula, V1 and V2 are the potential difference between the comb electrode, the parallel plate and the gyro structure respectively, C1(t) and C2(t) represent the derivative of the capacitance of the comb electrode and the parallel plate electrode with respect to time, i.e. the change rate of the capacitance with respect to time;

[0084] When the capacitive electrodes are used as excitation electrodes, the applied voltage will generate electrostatic force, and the alternating voltage V oc The periodic electrostatic force is generated, and the vibration of the first working mode and the second working mode is excited by the periodic electrostatic force. The comb electrode electrostatic force F1(t) and the parallel plate electrode electrostatic force F2(t) are calculated as:

[0085]

[0086] In the formula, V1 and V2 are the potential difference between the comb electrode, the parallel plate and the gyro structure respectively.

[0087] Based on the above principle, the full-symmetrical four-mass gyro can realize the excitation of the first working mode by electrostatic force and the calculation of the angular rate by the amplitude of the second working mode detected by the capacitance.

[0088] The orthogonal electrode 14 is further arranged on the sensitive mass block 201 to compensate for the error of the comb electrode 13 caused by the etching error when the comb electrode is machined in the driving capacitive frame 10.

[0089] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A fully symmetrical four-mass MEMS gyroscope, characterized in that, It includes four centrally symmetrically arranged sensitive mass block coupling structures, and four centrally symmetrically arranged first U-shaped beams, four Π-shaped beams, and a cross-shaped coupling structure connecting the four sensitive mass block coupling structures; the first U-shaped beams connect the trapezoidal coupling structures in the sensitive mass block coupling structures to absorb the force in the direction of the angle bisector of the entire structure perpendicular to the gyroscope; the Π-shaped beams are used to make the sensitive mass blocks in adjacent sensitive mass block coupling structures move in opposite directions, and the cross-shaped coupling structures are used to make the sensitive mass blocks in opposite sensitive mass block coupling structures move in opposite directions.

2. The fully symmetrical four-mass MEMS gyroscope according to claim 1, characterized in that, Each sensitive mass block coupling structure includes: a driving capacitor frame, a sensitive mass block, a driving detection capacitor frame, two L-shaped coupling structures, six J-shaped beams, four fixed anchor points, eight second U-shaped beams, and a trapezoidal coupling structure; The sensitive mass block has a right-angled triangle structure with the right angle point being the origin of the coordinate system. The direction of the axis of symmetry of the sensitive mass block is defined as the Y-axis, with the positive direction extending outward from the center. The direction perpendicular to the Y-axis is the X-axis, with the positive direction extending outward from the center. Adjacent sensitive mass blocks are connected by Π-shaped beams. The Π-shaped beam connection is used to enable the sensitive mass blocks arranged along the Y-axis to move in opposite phases to the sensitive mass blocks arranged along the X-axis. Two L-shaped coupling structures are connected to each other on the periphery of the driving capacitor frame; two sets of J-shaped beams are symmetrically arranged on both sides of the driving capacitor frame, each set having two J-shaped beams arranged along the X-axis direction, connected by L-shaped fixed anchor points; this is used to allow the sensitive mass block to vibrate freely in the Y-axis direction while effectively constraining and absorbing the motion in the X-axis direction; Two J-shaped beams are arranged symmetrically along the Y-axis on the side of the driving capacitor frame near the center of the structure. The J-shaped beams are fixedly connected to the sensitive mass block; this is used to realize the transmission of force in the X-axis direction and the absorption of motion in the Y-axis direction. The sensitive mass block is fixedly connected to the trapezoidal coupling structure on the side closest to the center of the structure; the trapezoidal coupling structure is used to transmit forces in the Y-axis direction and suppress forces in the X-axis direction; adjacent trapezoidal coupling structures are connected by a first U-shaped beam; The trapezoidal coupling structure is connected to the directional end of the cross-shaped coupling structure near the center of the structure; the cross-shaped coupling structure is used to transmit forces in the X and Y axes. Four fixed anchor points are set at the four corners of the drive detection capacitor frame. One end of the second U-shaped beam is fixedly connected to the fixed anchor point, and the other end is fixedly connected to the sensitive mass block.

3. The fully symmetrical four-mass MEMS gyroscope according to claim 2, characterized in that, Eight second U-shaped beams are arranged symmetrically around the drive detection capacitor frame, and each fixed anchor point is connected to two second U-shaped beams. The second U-shaped beams are used to make the drive capacitor frame move together with the sensitive mass block.

4. The fully symmetrical four-mass MEMS gyroscope according to claim 2, characterized in that, The gyroscope has four operating modes; First working mode: Of the four sensitive mass blocks, two of the opposite sensitive mass blocks expand outward along their respective Y-axis directions, while the other two opposite sensitive mass blocks contract inward along their respective Y-axis directions, driving the detection capacitor frame to remain stationary; In the second working mode, the sensitive mass block at the diagonal moves in the opposite direction, driving the detection box to move accordingly; In the third working mode, the four sensitive mass blocks expand outward along the Y-axis in the local coordinate system of their respective sensitive mass block coupling structures, while the driving detection capacitor frame remains unchanged. In the fourth working mode, the four axisymmetrically arranged sensitive mass blocks rotate counterclockwise or clockwise; the positions of the four axisymmetrically arranged driving capacitor frames remain unchanged.

5. The fully symmetrical four-mass MEMS gyroscope according to claim 3, characterized in that, The Coriolis force experienced by the sensitive mass block in the first working mode will excite the vibration in the second working mode; the Coriolis force experienced by the sensitive mass block in the third working mode will excite the vibration in the fourth working mode.

6. The fully symmetrical four-mass MEMS gyroscope according to claim 2, characterized in that, The drive capacitor frame is arranged in an axisymmetric manner, with comb-tooth electrodes arranged inside; the drive detection capacitor frame is arranged with parallel plate electrodes.

7. The fully symmetrical four-mass MEMS gyroscope according to claim 4, characterized in that, The sensitive mass block is also equipped with orthogonal electrodes to compensate for the comb electrode error caused by the etching error during the machining of the comb teeth in the drive capacitor frame.

8. The fully symmetrical four-mass MEMS gyroscope according to claim 2, characterized in that, One end of the L-shaped coupling structure is a double-folded beam, and the other end is a J-shaped beam. The L-shaped coupling structure reduces the stiffness of the driving capacitor frame along the Y-axis, thereby allowing the sensitive mass block to vibrate freely in the Y-axis direction. It also increases the stiffness of the driving capacitor frame along the X-axis, thus constraining the movement in the X-axis direction.

9. The fully symmetrical four-mass MEMS gyroscope according to claim 2, characterized in that, An anchor point is set in the middle of the cross-shaped coupling structure to increase its stability.

Images