CN112284368A - Fully-differential high-precision X-axis silicon micro-gyroscope - Google Patents
Fully-differential high-precision X-axis silicon micro-gyroscope Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 45
- 239000010703 silicon Substances 0.000 title claims abstract description 45
- 238000001514 detection method Methods 0.000 claims abstract description 103
- 230000008878 coupling Effects 0.000 claims abstract description 40
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- 238000005859 coupling reaction Methods 0.000 claims abstract description 40
- 238000006073 displacement reaction Methods 0.000 claims abstract description 25
- 239000000758 substrate Substances 0.000 claims description 22
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- 238000013461 design Methods 0.000 abstract description 5
- 230000035945 sensitivity Effects 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000005259 measurement Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 4
- 230000010354 integration Effects 0.000 description 4
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5607—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks
- G01C19/5621—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks the devices involving a micromechanical structure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
- G01C19/5733—Structural details or topology
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Abstract
The invention discloses a fully-differential high-precision X-axis silicon micro gyroscope which comprises a mass block group, a driving unit and a detection unit. The driving unit receives an electric signal input from the outside, generates an electrostatic force and drives the mass block to do simple harmonic vibration along the X direction; each mass block in the mass block group is sensitive to the external angular velocity around the Y axis while performing simple harmonic vibration, and generates displacement in the Z axis direction under the vibration of Coriolis force along the Z axis direction; and the detection unit converts the displacement of each mass block in the Z-axis direction into an electric signal and outputs the electric signal. The mass block group adopts a fully-symmetrical four-mass-block structural design to form fully-differential output, so that the relative nonlinear error of detection can be effectively reduced, the detection sensitivity is improved, meanwhile, the influence of external factors on the performance of the gyroscope can be reduced, and the environmental suitability is high. The driving unit and the detection unit are designed by adopting a mechanical decoupling structure, so that the mechanical coupling of a driving mode and a detection mode can be effectively reduced, and the detection precision is improved.
Description
Technical Field
The invention relates to a fully-differential high-precision X-axis silicon micro gyroscope, belongs to the field of sensors, can be applied to the national defense and commercial fields of aerospace, guidance bombs, mobile equipment, unmanned aerial vehicles, unmanned driving and the like, and is used for measuring the rotation angular rate of a carrier around a fixed shaft relative to an inertial space.
Background
Compared with the traditional mechanical gyroscope, the silicon micro gyroscope has the characteristics of low cost, small volume, light weight, easy integration and batch production, and has great application value in military and commercial fields of aerospace, unmanned driving, microminiature operation platforms, satellite navigation, internet of things, intelligent medical treatment and the like.
Silicon micro-gyroscopes are commonly used in combination with micro-accelerometers in small Inertial Measurement Units (IMUs). Because the traditional silicon micro gyroscope is generally a Z-axis gyroscope and is used for detecting yaw rate, if the IMU needs to detect the pitch rate and the roll rate simultaneously, the Z-axis gyroscope needs to be vertically placed. This arrangement results in an increase in the volume of the inertial measurement unit, which is not conducive to miniaturization of the micro inertial system. Compared with the advanced foreign technologies, the precision, the integration level and the like of the domestic single-chip integrated three-axis gyroscope still have larger gaps, the development and the application of domestic micro-inertia devices are greatly limited, and the coupling degree of the single-chip integrated three-axis gyroscope in each direction is higher, so that the single-chip integrated three-axis gyroscope is not beneficial to high-precision measurement. Therefore, the high-precision X-axis silicon micro gyroscope capable of measuring the pitch angle rate and the roll angle rate is designed, and the high-precision X-axis silicon micro gyroscope has important application value for small integration of the IMU.
Meanwhile, the silicon micro gyroscope generally adopts a capacitive detection principle, has the advantages of simple structure and easiness in processing, and is a non-contact measurement mode. However, the capacitive silicon micro gyroscope has interference such as parasitic capacitance, distributed capacitance and common mode noise, and measurement accuracy is reduced.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the defects of the prior art are overcome, the full-differential high-precision X-axis silicon micro-gyroscope is provided, the detection of the pitch angle rate and the roll angle rate under horizontal placement is realized, the anti-interference capability to parasitic capacitance, distributed capacitance and common-mode noise is improved, and the high-precision detection of the silicon micro-gyroscope under a complex vibration mechanical environment and a noise environment is realized.
The technical scheme of the invention is as follows: a fully-differential high-precision X-axis silicon micro gyroscope comprises a driving unit, a detection unit, a mass block group, a silicon substrate and a cap layer; the mass block is connected with the driving unit and the detection unit, is connected to the silicon substrate and the cap layer through the anchor area, and is positioned in a vacuum environment between the silicon substrate and the cap layer;
the mass block group comprises four mass blocks which are symmetrically distributed about the center of the gyroscope structure and are respectively marked as a first mass block, a second mass block, a third mass block and a fourth mass block, and the first mass block and the third mass block are symmetrically arranged about the positive direction axis of the Y axis; the second mass block and the fourth mass block are arranged in an axial symmetry mode around the Y-axis negative direction; the first mass block and the second mass block are arranged symmetrically about the X-axis negative direction axis; the third mass block and the fourth mass block are arranged in axial symmetry around the positive direction of the X axis; the first mass block and the fourth mass block are arranged in a central symmetry manner; the third mass block and the second mass block are arranged in a central symmetry manner;
the driving unit receives an electric signal input from the outside, generates an electrostatic force and drives the mass block to do simple harmonic vibration along the X direction; each mass block in the mass block group is sensitive to the external angular velocity around the Y axis while performing simple harmonic vibration, and generates displacement in the Z axis direction under the vibration of Coriolis force along the Z axis direction; and the detection unit converts the displacement of each mass block in the Z-axis direction into an electric signal and outputs the electric signal.
The specific situation that the mass block group is driven in a simple harmonic mode along the X-axis direction is as follows: the four mass blocks vibrate along the X direction, and the vibration directions of the two adjacent mass blocks are opposite in phase, namely the vibration directions of the first mass block and the third mass block are opposite in phase; the vibration directions of the first mass block and the second mass block are opposite in phase, the vibration directions of the third mass block and the fourth mass block are opposite in phase, and the vibration directions of the second mass block and the fourth mass block are opposite in phase.
The specific situation that the mass block group is subjected to Coriolis force and vibrates along the Z-axis direction is as follows: the four mass blocks vibrate up and down along the Z direction, and the vibration directions of two adjacent mass blocks are opposite in phase, namely the vibration directions of the first mass block and the third mass block are opposite in phase; the vibration directions of the first mass block and the second mass block are opposite in phase, the vibration directions of the third mass block and the fourth mass block are opposite in phase, and the vibration directions of the second mass block and the fourth mass block are opposite in phase.
The driving unit includes: 4 driving frames, 16 driving elastic beams, 4 driving electrodes, 4 driving feedback electrodes, 2 coupling elastic beams and 2 coupling suppression elastic beam groups;
the driving frames are respectively marked as a first driving frame, a second driving frame, a third driving frame and a fourth driving frame;
each driving frame is connected to the anchoring area through a driving elastic beam; each driving frame is connected with a driving electrode and a driving feedback electrode, and the driving electrodes are used for driving the mass block to do simple harmonic vibration along the X direction; the driving feedback electrode is used for detecting simple harmonic vibration of the mass block along the X direction;
the 2 coupling elastic beams are respectively marked as a first coupling elastic beam and a second coupling elastic beam; the first driving frame is connected with the third driving frame through a first coupling elastic beam, and the second driving frame is connected with the fourth driving frame through a second coupling elastic beam;
2 coupling suppression elastic beam groups which are respectively marked as a first coupling suppression elastic beam group and a second coupling suppression elastic beam group; the first driving frame and the second driving frame are connected through the first coupling suppression elastic beam group, and the third driving frame and the fourth driving frame are connected through the second coupling suppression elastic beam group.
The detection unit includes: 16 detection elastic beams and 4 detection electrodes;
each driving frame is distributed with 4 detection elastic beams and a detection electrode, and specifically, a first mass block is connected with a first driving frame through the 4 detection elastic beams; the second mass block is connected with the second driving frame through 4 detection elastic beams; the third mass block is connected with a third driving frame through 4 detection elastic beams; the fourth mass block is connected with the fourth driving frame through 4 detection elastic beams; the lower surface of the mass block and the upper surface of the substrate layer form detection capacitors, and the detection electrodes are connected to the substrate and correspond to the detection capacitors one by one;
when an angular velocity is input, each mass block generates a Z-direction inertia force to cause the first mass block, the second mass block, the third mass block and the fourth mass block to generate displacement in the Z direction, the variation of the displacement is in direct proportion to the input angular velocity, and the displacement phases of the adjacent mass blocks are opposite, so that the capacitance corresponding to the adjacent electrodes detected by the four detection electrodes on the substrate is increased, and the capacitance of the other adjacent electrode is reduced; and outputting a differential signal of two adjacent detection signals in the X direction or the Y direction as a detection signal of a detection mode.
The driving electrode and the driving feedback electrode adopt a sliding film comb tooth structure, and each row of driving comb teeth are vertically fixed on the corresponding driving frame at equal intervals.
The rigidity of the driving elastic beam in the X direction is more than 6 times of the maximum rigidity in the Y, Z direction.
The rigidity of the detection elastic beam in the Z direction is more than 6 times of the maximum rigidity in the X, Y direction.
Compared with the prior art, the invention has the following beneficial effects:
(1) the mass block group adopts the design of a fully-symmetrical four-mass block structure to form fully-differential output, can form stress self-offset under the input of vibration conditions, can effectively reduce the relative nonlinear error of detection, can improve the detection sensitivity, can reduce the influence of external factors on the performance of the gyroscope, greatly improves the anti-vibration characteristic and has strong environmental adaptability compared with a single-mass single tuning fork structure.
(2) The driving unit and the detection unit are designed by adopting a mechanical decoupling structure, and the driving mode and the detection mode have independent beams, so that the mechanical coupling of the driving mode and the detection mode can be effectively reduced, and the detection precision is improved.
(3) The invention can realize the measurement of the horizontal angular rate of the silicon micro-electromechanical gyroscope in a complex vibration mechanics environment, and can measure pitch and roll angular rate signals when the silicon micro-electromechanical gyroscope is horizontally placed compared with the traditional tuning fork driving Z-axis gyroscope which can only measure yaw angular rate signals when the silicon micro-electromechanical gyroscope is horizontally placed;
(4) the detection capacitance has large variation, so that the detection sensitivity is higher;
(5) the horizontal axis gyroscope designed by the invention can be integrated on a three-axis micro-gyroscope system, and compared with the integration of three traditional Z-axis gyroscopes, the size of the system can be effectively reduced.
Drawings
FIG. 1 is a schematic block diagram of a high-precision horizontal-axis silicon micro-gyroscope based on tuning fork driving effect according to the present invention;
FIG. 2 is a driving resonance mode diagram of the high-precision horizontal-axis silicon micro-gyroscope based on tuning fork driving effect according to the present invention;
FIG. 3 is a diagram of the resonance mode of the high-precision horizontal-axis silicon micro gyroscope based on tuning fork driving effect according to the present invention;
Detailed Description
The invention will be further elucidated and described with reference to the drawings and the detailed description.
As shown in fig. 1, the gyroscope sensitive structure of the fully-differential high-precision X-axis silicon micro-gyroscope provided by the invention adopts a four-mass fully-differential structure design, and comprises a driving unit, a detection unit, a mass block group, a silicon substrate and a cap layer; the mass block is connected with the driving unit and the detection unit, is connected to the silicon substrate and the cap layer through the anchor area, and is positioned in a vacuum environment between the silicon substrate and the cap layer; the mass block group comprises four mass blocks which are symmetrically distributed about the center of the gyroscope structure and are respectively marked as a first mass block 121, a second mass block 122, a third mass block 123 and a fourth mass block 124, and the first mass block 121 and the third mass block 123 are symmetrically arranged about the positive direction axis of the Y axis; the second mass 122 and the fourth mass 124 are arranged axisymmetrically with respect to the negative Y-axis direction; the first mass block 121 and the second mass block 122 are arranged axially symmetrically about the negative X-axis direction; the third mass 123 and the fourth mass 124 are arranged axisymmetrically with respect to the positive X-axis direction; the first mass 121 and the fourth mass 124 are arranged centrosymmetrically; the third mass 123 is arranged centrosymmetrically to the second mass 122;
the driving unit receives an electric signal input from the outside, generates an electrostatic force and drives the mass block to do simple harmonic vibration along the X direction; each mass block in the mass block group is sensitive to the external angular velocity around the Y axis while performing simple harmonic vibration, and vibrates along the Z axis direction under the action of Coriolis force to generate displacement in the Z axis direction; and the detection unit converts the displacement of each mass block in the Z-axis direction into an electric signal and outputs the electric signal.
The driving unit includes: 4 driving frames 15, 16 driving elastic beams 9, 4 driving electrodes, 4 driving feedback electrodes, 2 coupling elastic beams 13 and 2 coupling suppression elastic beam groups 14;
4 driving frames 15, which are respectively referred to as a first driving frame 151, a second driving frame 152, a third driving frame 153, and a fourth driving frame 154; the first mass 121 is disposed inside the first driving frame 151, the second mass 122 is disposed inside the second driving frame 152, the third mass 123 is disposed inside the third driving frame 153, and the fourth mass 124 is disposed inside the fourth driving frame 154. The maximum drive displacement of the drive frame in the X direction is determined by the stop gap, typically 10 um.
The 16 driving elastic beams 9 are respectively referred to as a first driving elastic beam, a second driving elastic beam, a third driving elastic beam, a fourth driving elastic beam, a fifth driving elastic beam, a sixth driving elastic beam, a seventh driving elastic beam, a third driving elastic beam, a ninth driving elastic beam, a tenth driving elastic beam, an eleventh driving elastic beam, a twelfth driving elastic beam, a thirteenth driving elastic beam, a fourteenth driving elastic beam, a fifteenth driving elastic beam, and a sixteenth driving elastic beam. The driving elastic beams are respectively positioned on the periphery of the four driving frames and connected with the anchor area, and specifically comprise: each driving frame 15 is connected to the anchoring zone 11 by 4 driving elastic beams 9; the anchor region 11 is fixedly connected between the silicon substrate and the cap layer. The 4 drive electrodes are respectively designated as a first drive electrode 1, a second drive electrode 2, a third drive electrode 3, and a fourth drive electrode 4. The 4 driving feedback electrodes are respectively marked as a first driving feedback electrode 5, a second driving feedback electrode 6, a third driving feedback electrode 7 and a fourth driving feedback electrode 8.
Each driving frame 15 is connected with a driving electrode and a driving feedback electrode, and the driving electrodes are used for driving the mass block to do simple harmonic vibration along the X direction; the driving feedback electrode is used for detecting simple harmonic vibration of the mass block along the X direction; the driving electrode and the driving feedback electrode are fixed outside the driving frame. The upper end of the first driving frame 151 is connected with a first driving electrode 1 and a first driving feedback electrode 5; the upper end of the third driving frame 153 is connected with the third driving electrode 3 and the third driving feedback electrode 7; the lower end of the second driving frame 152 is connected with two driving electrodes 2 and a second driving feedback electrode 6; the lower end of the fourth driving frame 154 is connected to the fourth driving electrode 4 and the fourth driving feedback electrode 8.
2 coupling elastic beams 13, which are respectively marked as a first coupling elastic beam 131 and a second coupling elastic beam 132; the first driving frame 151 and the third driving frame 153 are connected by the first coupling elastic beam 131, and the second driving frame 152 and the fourth driving frame 154 are connected by the second coupling elastic beam 132. The mass block is symmetrical about the central axis of the gyroscope structure, the frequency difference between a driving mode and an interference mode can be optimized by adjusting the rigidity of the coupling elastic beam, and the influence of the interference mode on the driving mode is reduced.
2 coupling suppression elastic beam groups 14, which are respectively marked as a first coupling suppression elastic beam group 141 and a second coupling suppression elastic beam group 142; the first driving frame 151 and the second driving frame 152 are connected by the first coupling suppression elastic beam set 141, and the third driving frame 153 and the fourth driving frame 154 are connected by the second coupling suppression elastic beam set 142, so that the in-phase vibration of the mass 121 and the mass 122, and the in-phase vibration of the mass 123 and the mass 124 can be suppressed.
The detection unit includes: 16 detection elastic beams 10 and 4 detection electrodes. One end of the detection elastic beam is connected with the mass block, and the other end of the detection elastic beam is connected with the driving frame.
Each driving frame 15 is allocated with 4 detection elastic beams 10 and one detection electrode, the detection elastic beams are respectively positioned in the middle of the upper end, the middle of the left end, the middle of the lower end and the middle of the right end of the corresponding mass block, and specifically, the first mass block 121 is connected with the first driving frame 151 through the 4 detection elastic beams 1001, 1002, 1003 and 1004; the second mass 122 is connected to the second drive frame 152 by 4 sense spring beams 1005, 1006, 1007, 1008; the third mass 123 is connected to the third driving frame 153 via 4 sensing elastic beams 1009, 1010, 1011, 1012; the fourth mass 124 is connected to the fourth drive frame 154 via 4 sense spring beams 1013, 1014, 1015, 1016; the lower surface of the mass block and the upper surface of the substrate layer form detection capacitors, and the detection electrodes are connected to the substrate and correspond to the detection capacitors one to one.
When an angular velocity is input, each mass block generates a Z-direction inertia force, so that the first mass block 121, the second mass block 122, the third mass block 123 and the fourth mass block 124 generate displacement in the Z direction, the variation of the displacement is proportional to the input angular velocity, and the displacement phases of the adjacent mass blocks are opposite, so that the capacitance of the adjacent electrodes detected by the four detection electrodes on the substrate is increased, and the capacitance of the adjacent electrodes is reduced; the differential signal of two adjacent detection signals in the X direction or the Y direction is output as a detection signal of a detection mode, so that the interference of common-mode noise can be effectively inhibited, and the angular rate can be calculated by demodulating the detection capacitor through a peripheral circuit.
4 drive electrodes and 4 drive feedback electrodes are fixed in drive frame 15 outside, adopt synovial membrane broach structure, and every row of drive broach is equidistant vertical fixation in corresponding drive frame 15 upper end or lower extreme.
The rigidity of the driving elastic beam 9 in the X direction is far less than that in the Y, Z direction, so that only one degree of freedom in the X direction is provided, the vibration of the frame in the Y, Z direction can be effectively inhibited, the mode decoupling of a driving mode and a detection mode is realized, the orthogonal error is effectively inhibited, and the precision is improved; preferably, the rigidity of the driving elastic beam 9 in the X direction is more than 6 times of the maximum rigidity in the Y, Z direction.
The rigidity in the Z direction is far less than that in the X, Y direction, so that the mass block 12 is driven to have only the freedom degree in the Z direction, and therefore, the Z-direction movement of the mass block 12 in the detection mode does not cause the displacement of the frame in the X direction, so that the decoupling of the detection mode on the driving mode is realized; preferably, the rigidity of the detection elastic beam 10 in the Z direction is more than 6 times of the maximum rigidity in the X, Y direction.
The detection capacitor is composed of the lower surface of the mass block and the upper surface of the substrate layer; the detection feedback capacitor is positioned around the detection capacitor. The capacitance gap of the detection capacitor can be designed according to different detection circuits and application environments, and the typical value is 2 um.
The X direction of the present invention is defined as the driving direction and the Z direction is defined as the detecting direction. The driving mode is that the mass blocks move left and right in the X direction, and the motion phases of the adjacent mass blocks are opposite; the detection mode is the out-of-plane motion of the mass block in the Z direction, and the motion phases of the adjacent mass blocks are opposite.
The motion mode of drive shaft is that the quality block group does the simple harmonic drive along X axle direction under the operating mode, and the concrete condition is: the four mass blocks vibrate along the X direction, and the vibration directions of the two adjacent mass blocks are opposite in phase, that is, the vibration directions of the first mass block 121 and the third mass block 123 are opposite in phase; the first mass 121 and the second mass 122 vibrate in opposite phases, the third mass 123 and the fourth mass 124 vibrate in opposite phases, and the second mass 122 and the fourth mass 124 vibrate in opposite phases.
In the working mode, the motion mode of the detection shaft is that the mass block group is subjected to Coriolis force and vibrates along the Z-axis direction. The concrete situation is as follows: the four mass blocks vibrate up and down along the Z direction, and the vibration directions of two adjacent mass blocks are opposite in phase, that is, the vibration directions of the first mass block 121 and the third mass block 123 are opposite in phase; the first mass 121 and the second mass 122 vibrate in opposite phases, the third mass 123 and the fourth mass 124 vibrate in opposite phases, and the second mass 122 and the fourth mass 124 vibrate in opposite phases.
The working principle of the invention is as follows: when the silicon micro gyroscope is in a working mode, the mass blocks perform constant amplitude resonant motion in the X direction, when an angular velocity is input, each mass block generates a Z-direction inertia force, so that the first mass block 121, the second mass block 122, the third mass block 123 and the fourth mass block 124 generate displacement in the Z direction, the variation of the displacement is in direct proportion to the input angular velocity, and the displacement phases of the adjacent mass blocks are opposite, so that the capacitance of the adjacent electrode detected by four detection electrodes on the substrate is increased, and the capacitance of the other electrode is reduced. The difference between the two adjacent detection signals is used as a detection signal of a detection mode, so that the interference of common mode noise, such as external impact noise, circuit noise and the like, can be effectively inhibited, and the angular rate can be calculated by demodulating the detection capacitor through a peripheral circuit.
When angular velocity along the Y axis is input, each mass block generates Z-direction inertia force, so that the mass blocks generate displacement in the Z direction, and the variation of the displacement is proportional to the input angular velocity.
In addition, the invention adopts a four-mass double-tuning fork fully-differential structure design, can form stress self-offset under the input of vibration conditions, can effectively improve the anti-interference capability on parasitic capacitance, distributed capacitance and common-mode noise, reduces thermoelastic loss, improves the quality factor under vacuum, further improves the mechanical sensitivity, and realizes the high-precision detection of the pitching and rolling speed of the silicon micro gyroscope in a complex vibration mechanical environment and a noise environment. Example 1:
fig. 1 is an outline drawing of a fully differential high-precision X-axis silicon micro gyroscope of the present invention, in which a sensitive axial Z-axis, four-mass microstructures are arranged in a left-right-up-down fully symmetric manner, and a working frequency can be designed by adjusting the size of a driving beam, and preferably, the working frequency of this embodiment is about 12 KHz.
As shown in fig. 2, which is a schematic diagram of a driving mode of a fully differential high-precision X-axis silicon micro gyroscope according to the present invention, two adjacent mass blocks vibrate in opposite phases, that is, the vibration directions of the first mass block 121 and the second mass block 122 are opposite in phase; the third mass 123 and the fourth mass 124 vibrate in opposite phases, the first mass 121 and the third mass 123 vibrate in opposite phases, and the second mass 122 and the fourth mass 124 vibrate in opposite phases.
In an embodiment, the external driving circuit applies an alternating current bias signal to drive the driving frame to vibrate in a simple harmonic mode in the X direction through the first driving electrode 1, the second driving electrode 2, the third driving electrode 3 and the fourth driving electrode 4; the phase of the alternating current bias signals of the first driving electrode positive end 1-1, the second driving electrode positive end 2-1, the third driving electrode positive end 3-1 and the fourth driving electrode positive end 4-1 are opposite to the phase of the alternating current bias signals of the first driving electrode negative end 1-2, the second driving electrode negative end 2-2, the third driving electrode negative end 3-2 and the fourth driving electrode negative end 4-2.
The first, second, third and fourth driving frames 151, 152, 153 and 154 are driven by electrostatic force to move the first, second, third and fourth masses 121, 122, 123 and 124 left and right in the X direction, wherein the vibration directions of the first and second masses 121 and 122 are opposite; the vibration directions of the third mass block 123 and the fourth mass block 124 are opposite, the vibration directions of the first mass block 121 and the third mass block 123 are opposite, and the vibration directions of the second mass block 122 and the fourth mass block 124 are opposite; in addition, the external circuit can realize the closed-loop driving of the gyroscope through the feedback electrode.
Fig. 3 shows the detection mode of the horizontal axis silicon micro gyroscope according to the present invention. When an angular velocity is input from the outside, the mass blocks are subjected to the coriolis force to generate displacement in the detection direction, and the motion mode of the detection mode is the vibration opposite phase of the adjacent mass blocks in the Z direction, that is, the vibration directions of the first mass block 121 and the fourth mass block 122 are opposite phases; the third mass 123 and the fourth mass 124 vibrate in opposite phases, the first mass 121 and the third mass 123 vibrate in opposite phases, and the second mass 122 and the fourth mass 124 vibrate in opposite phases.
The vibration of the first mass block 121, the second mass block 122, the third mass block 123 and the fourth mass block 124 in the Z direction causes the change of the gap of the detection capacitor, and the size of the angular rate can be demodulated through detecting the size of the change of the capacitance, so that the measurement of the angular rate is realized;
because of adopting the full differential design, the capacitance of the adjacent electrode detected by the four detection electrodes on the substrate is increased by one capacitance, the capacitance of the adjacent electrode is reduced by the other capacitance, and the two adjacent detection signals are subtracted to be used as the detection signal of the detection mode, so that the interference of parasitic capacitance and common mode noise can be effectively inhibited.
The invention relates to a fully-differential high-precision X-axis silicon micro-electro-mechanical gyroscope which has high measurement precision, can be widely applied to military and commercial fields of aerospace, unmanned driving, microminiature operation platforms, satellite navigation, Internet of things, intelligent medical treatment and the like, is used for measuring the rotation angular rate of a carrier around a fixed shaft relative to an inertial space, and can also effectively reduce the volume of a triaxial integrated micro-inertial system. Without departing from the technical principle of the present invention, several modifications and variations can be made, and these modifications and variations should also be regarded as the scope of the present invention.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.
Claims (8)
1. A fully-differential high-precision X-axis silicon micro gyroscope is characterized by comprising a driving unit, a detection unit, a mass block group, a silicon substrate and a cap layer; the mass block is connected with the driving unit and the detection unit, is connected to the silicon substrate and the cap layer through the anchor area, and is positioned in a vacuum environment between the silicon substrate and the cap layer;
the mass block group comprises four mass blocks which are symmetrically distributed about the center of the gyroscope structure and are respectively marked as a first mass block (121), a second mass block (122), a third mass block (123) and a fourth mass block (124), and the first mass block (121) and the third mass block (123) are symmetrically arranged about the positive direction axis of the Y axis; the second mass block (122) and the fourth mass block (124) are arranged in axial symmetry about the Y-axis negative direction; the first mass block (121) and the second mass block (122) are arranged in an axial symmetry mode around the X-axis negative direction; the third mass block (123) and the fourth mass block (124) are arranged in axial symmetry around the positive X-axis direction; the first mass block (121) and the fourth mass block (124) are arranged in a central symmetry manner; the third mass block (123) and the second mass block (122) are arranged in a central symmetry mode;
the driving unit receives an electric signal input from the outside, generates an electrostatic force and drives the mass block to do simple harmonic vibration along the X direction; each mass block in the mass block group is sensitive to the external angular velocity around the Y axis while performing simple harmonic vibration, and generates displacement in the Z axis direction under the vibration of Coriolis force along the Z axis direction; and the detection unit converts the displacement of each mass block in the Z-axis direction into an electric signal and outputs the electric signal.
2. The fully-differential high-precision X-axis silicon micro-gyroscope according to claim 1, wherein the mass block is driven in a simple harmonic manner along the X-axis direction by: the four mass blocks vibrate along the X direction, and the vibration directions of the two adjacent mass blocks are opposite in phase, namely the vibration directions of the first mass block (121) and the third mass block (123) are opposite in phase; the vibration directions of the first mass block (121) and the second mass block (122) are opposite, the vibration directions of the third mass block (123) and the fourth mass block (124) are opposite, and the vibration directions of the second mass block (122) and the fourth mass block (124) are opposite.
3. The fully-differential high-precision X-axis silicon micro-gyroscope of claim 1, wherein the mass block group is vibrated along the Z-axis by the Coriolis force in the specific case: the four mass blocks vibrate up and down along the Z direction, and the vibration directions of the two adjacent mass blocks are opposite in phase, namely the vibration directions of the first mass block (121) and the third mass block (123) are opposite in phase; the vibration directions of the first mass block (121) and the second mass block (122) are opposite, the vibration directions of the third mass block (123) and the fourth mass block (124) are opposite, and the vibration directions of the second mass block (122) and the fourth mass block (124) are opposite.
4. The fully-differential high-precision X-axis silicon micro-gyroscope according to claim 1, characterized in that the driving unit comprises: 4 driving frames (15), 16 driving elastic beams (9), 4 driving electrodes, 4 driving feedback electrodes, 2 coupling elastic beams (13) and 2 coupling suppression elastic beam groups (14);
4 drive frames (15) respectively designated as a first drive frame (151), a second drive frame (152), a third drive frame (153), and a fourth drive frame (154);
each driving frame (15) is connected to the anchoring area (11) by 4 driving elastic beams (9); each driving frame (15) is connected with a driving electrode and a driving feedback electrode, and the driving electrodes are used for driving the mass block to do simple harmonic vibration along the X direction; the driving feedback electrode is used for detecting simple harmonic vibration of the mass block along the X direction;
2 coupling elastic beams (13) which are respectively marked as a first coupling elastic beam (131) and a second coupling elastic beam (132); the first driving frame (151) and the third driving frame (153) are connected through a first coupling elastic beam (131), and the second driving frame (152) and the fourth driving frame (154) are connected through a second coupling elastic beam (132);
2 coupling suppression elastic beam groups (14) which are respectively marked as a first coupling suppression elastic beam group (141) and a second coupling suppression elastic beam group (142); the first driving frame (151) and the second driving frame (152) are connected through a first coupling suppression elastic beam set (141), and the third driving frame (153) and the fourth driving frame (154) are connected through a second coupling suppression elastic beam set (142).
5. The fully-differential high-precision X-axis silicon micro-gyroscope according to claim 1, characterized in that the detection unit comprises: 16 detection elastic beams (10) and 4 detection electrodes;
each driving frame (15) is distributed with 4 detection elastic beams (10) and one detection electrode, and particularly, the first mass block (121) is connected with the first driving frame (151) through the 4 detection elastic beams (1001, 1002, 1003 and 1004); the second mass block (122) is connected with the second driving frame (152) through 4 detection elastic beams (1005, 1006, 1007, 1008); the third mass block (123) is connected with a third driving frame (153) through 4 detection elastic beams (1009, 1010, 1011 and 1012); the fourth mass (124) is connected with the fourth driving frame (154) through 4 detection elastic beams (1013, 1014, 1015, 1016); the lower surface of the mass block and the upper surface of the substrate layer form detection capacitors, and the detection electrodes are connected to the substrate and correspond to the detection capacitors one by one;
when an angular velocity is input, each mass block generates a Z-direction inertia force to cause the first mass block (121), the second mass block (122), the third mass block (123) and the fourth mass block (124) to generate displacement in the Z direction, the variation of the displacement is in direct proportion to the input angular velocity, and the displacement phases of the adjacent mass blocks are opposite, so that the capacitance corresponding to the adjacent electrodes detected by the four detection electrodes on the substrate is increased, and the capacitance of the adjacent electrodes is reduced; and outputting a differential signal of two adjacent detection signals in the X direction or the Y direction as a detection signal of a detection mode.
6. The fully differential high-precision X-axis silicon micro-gyroscope according to claim 1, characterized in that the driving electrodes and the driving feedback electrodes are in a slip film comb structure, and each row of driving combs are vertically fixed on the corresponding driving frame (15) at equal intervals.
7. The fully differential high-precision X-axis silicon micro-gyroscope according to claim 1, characterized in that the stiffness of the driving elastic beam (9) in the X-direction is more than 6 times the maximum stiffness in the Y, Z-direction.
8. The fully-differential high-precision X-axis silicon micro-gyroscope according to claim 1, characterized in that the stiffness of the detection elastic beam (10) in the Z direction is more than 6 times greater than the maximum stiffness in the X, Y direction.
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