MEMS gyroscope structure with amplitude amplification function

Abstract

According to the technical scheme provided by the invention, a structure combining an elliptical annular structure and a comb tooth structure is provided to form a lever effect to amplify the displacement of a sensitive mode, a parasitic mode between a driving mode and the sensitive mode is eliminated, and meanwhile, the long-term and short-term zero-bias stability of the gyroscope is improved; according to the technical scheme, the symmetrical large-area sensitive mass blocks are adopted, the advantage of decoupling of a driving mode and a detection mode is achieved, and meanwhile large signal output gain is achieved; the sensitive mass block and the detection frame which are symmetrical are adopted, differential detection can be achieved, the same external interference is differentiated, and the sensitivity and the anti-interference capacity are further guaranteed; and the symmetrical structure can effectively restrain machining errors, so that the stability of the gyroscope is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon micromechanical gyroscopes, and particularly relates to a MEMS gyroscope structure with amplitude amplification. BACKGROUND

[0002] A gyroscope is a sensor that measures the rotational motion of a carrier relative to the inertial space, and is a core device in the fields of motion measurement, inertial navigation, platform stabilization, etc. It has very important application value in high-end industrial equipment such as aerospace, intelligent robots, automobile electronics, and unmanned aerial vehicles. At present, gyroscopes mainly include rotor gyroscopes, fiber-optic gyroscopes, laser gyroscopes, and micro-electro-mechanical system (MEMS) gyroscopes. Among them, a capacitive silicon micromechanical gyroscope is an inertial sensor based on MEMS technology, which has been widely used in many fields such as aerospace, automobile electronics, and consumer electronics due to its small size, low cost, high reliability, and batch production. However, with the increasing demand for applications, the problems of insufficient sensitivity and poor zero bias stability have gradually become prominent, which have become key factors restricting its further development.

[0003] The sensitivity of a capacitive silicon micromechanical gyroscope refers to the ratio of its output signal to input angular velocity. The higher the sensitivity, the stronger the detection ability of the gyroscope to small angular velocity changes. However, the current capacitive silicon micromechanical gyroscope has some deficiencies in terms of sensitivity. For example, due to structural design limitations, the sensitivity of the gyroscope is closely related to the matching degree of the drive mode and the detection mode. If the natural frequencies of the two modes do not match, it will lead to a decrease in energy transfer efficiency, thereby reducing the sensitivity. In actual application, it is easily affected by environmental factors such as temperature changes and mechanical vibrations, which will cause the sensitivity of the gyroscope to decrease. The zero bias stability refers to the stability of the output signal of the gyroscope when there is no input angular velocity. Poor zero bias stability will cause the measurement error of the gyroscope to increase, affecting its accuracy in long-time measurement. The zero bias stability problem of the capacitive silicon micromechanical gyroscope is mainly due to the process during the processing of the gyroscope, which will cause a large amount of structural residual stress in the structure. These residual stresses will affect the resonant frequency of the gyroscope, thereby causing the zero bias stability to deteriorate. In addition, environmental factors such as temperature changes and electromagnetic interference will also affect the zero bias of the gyroscope, making it exhibit different zero bias characteristics in different environments. Furthermore, due to the structural design and processing precision limitations of the gyroscope, there may be mechanical coupling between the drive mode and the detection mode, which will cause the fluctuation of the zero bias.

[0004] The capacitive silicon micromechanical gyroscope faces the problems of insufficient sensitivity and poor zero bias stability in actual application, which limits its application in high-precision measurement fields. In the prior art, attempts are often made to improve the performance of the gyroscope and solve these problems through structural design optimization, process improvement, and the application of signal processing technology.

[0005] However, there is no ideal solution to solve the above problems at present, and the structural design optimization is low in cost and good in effect among many solutions, therefore, in combination with the problems of the silicon micromechanical gyroscope, a structure capable of improving the sensitivity of the gyroscope is proposed to improve the accuracy (short-term zero bias stability) of the gyroscope, so as to meet the increasing application demand, which is of great significance. SUMMARY

[0006] The present application is directed to the problem of insufficient sensitivity and poor zero bias stability of the silicon micromechanical gyroscope in the prior art, and a MEMS gyroscope structure with amplitude amplification is provided. The technical scheme of the present application optimizes the structure of the gyroscope, and proposes an elliptical ring structure combined with a comb structure to form a lever action to amplify the displacement of the sensitive mode. In the structure, the driving structure, the detection structure and the mass block are independent of each other, the driving structure is limited by the driving frame lever and can only move in the driving direction, the detection structure is limited by its supporting structure and can only move in the detection direction, and the mass block has two degrees of freedom in the plane and can realize decoupling. The size of the key flexible beam is systematically adjusted instead of changing the topological configuration, the driving mode and the detection mode frequency are regulated to the first three orders of the system, and the frequency of the main parasitic mode is pushed to the fourth order or higher, so as to eliminate the parasitic mode between the driving mode and the sensitive mode, and improve the long-term and short-term zero bias stability of the gyroscope.

[0007] The present application is realized by the following technical means: A MEMS gyroscope structure with amplitude amplification function, comprising a driving frame and at least one set of two mass blocks, driving structure and detection structure, the driving frame is composed of x-axis rigid beams 8a and 8b and y-axis rigid beams 9a and 9b connected to the left and right ends of the x-axis rigid beams 8a and 8b respectively, and the x-axis rigid beams 8a and 8b are fixed on anchor points 1a and 1b; the y-axis rigid beams 9a and 9b are connected to the two mass blocks 7a and 7b respectively.

[0008] The driving structure comprises detection-driving decoupling beams 24a and 24b and multiple sets of comb structures, the detection-driving decoupling beams 24a and the comb structures are connected to the y-axis rigid beam 9a and symmetrically distributed on both sides of the mass block 7a, the detection-driving decoupling beams 24b and the comb structures are connected to the y-axis rigid beam 9b and symmetrically distributed on both sides of the mass block 7b; the detection-driving decoupling beams 24a and 24b are symmetrical about the y-axis rigid beams 9a and 9b and their end points are fixed on the anchor points; each set of comb structure is composed of movable comb 21, driving comb 22 and driving detection comb 23, and the movable comb 21 is connected to the y-axis rigid beams 9a and 9b of the driving frame; The detection structure includes an elliptical magnifying detection beam 11, detection sensitive beams 12a and 12b, drive-detection decoupling beams 13a and 13b, detection beam 14, detection beam 15, and multiple sets of comb tooth structures. Specifically: two mass blocks 7a and 7b are connected to the top of the major semi-axis of the elliptical ring of the elliptical magnifying detection beam 11 via the two detection sensitive beams 12a and 12b, respectively; each set of comb tooth structures includes movable comb teeth, coupled to the top of the minor semi-axis of the elliptical ring of the elliptical magnifying detection beam 11; detection beams 14 and 15 are connected to movable comb teeth 20a and 20d in the comb tooth structure, respectively, and their endpoints are fixed to anchor points; drive-detection decoupling beams 13a and 13b are connected to detection sensitive beams 12a and 12b, respectively, and their endpoints are fixed to anchor points; in the detection mode, the mass blocks are coupled to each other via detection sensitive beams 12a and 12b, magnifying detection beam 11, and detection beams 14 and 15.

[0009] Furthermore, when the two mass blocks, driving structure, and detection structure exceed one set, it also includes driving coupling beams 10a and 10b respectively installed on rigid beams 9a and 9b on the y-axis and located between each set of mass blocks, and the detection structure of each set is connected by beam 25.

[0010] Furthermore, the adjacent mass blocks move in opposite directions.

[0011] Furthermore, the driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the x-axis.

[0012] Furthermore, the driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the y-axis.

[0013] Furthermore, the x-axis rigid beams 8a and 8b are fixed at anchor points 1a and 1b at the center of the drive frame and are connected by short beams.

[0014] Furthermore, the detection-drive decoupling beams 24a and 24b, detection beams 14 and 15, and drive-detection decoupling beams 13a and 13b are all fixed at the anchor points at the two ends of the beams.

[0015] It should be noted that, as a type of ellipse, the circular shape, and the aforementioned magnified detection beam 11 being circular, means that the displacement is magnified by a factor of 1, but it is still within the scope of protection of this application.

[0016] The technical solution provided by this invention has the following beneficial technical effects: 1. A structure combining an elliptical ring structure and a comb structure is proposed to form a lever effect to amplify the displacement of the sensitive mode. The driving structure, detection structure and mass block are independent of each other. The driving structure is restricted by the driving frame lever and can only move in the driving direction. The detection structure is restricted by its supporting structure and can only move in the detection direction. The mass block has two degrees of freedom in the plane, which can achieve decoupling. The size of the key flexible beam is systematically adjusted instead of changing the topology, and the frequencies of the driving mode and the detection mode are tuned to the first three orders of the system. The frequency of the main parasitic mode is pushed to the fourth order or higher, thereby eliminating the parasitic mode between the driving mode and the sensitive mode, and improving the long-term and short-term zero-bias stability of the gyroscope.

[0017] 2. According to the technical solution of the present invention, at least two symmetrical large-area sensitive mass blocks are used in each group, which has the advantage of decoupling the driving mode and the detection mode, and also has a large signal output gain.

[0018] 3. The use of symmetrical sensitive mass blocks and detection frames, as well as other symmetrical structures, enables differential detection. External interference is processed differentially, further ensuring sensitivity and anti-interference capability. Moreover, the symmetrical structure can effectively suppress manufacturing errors, thereby improving the stability of the gyroscope. Attached Figure Description

[0019] Figure 1 A schematic diagram of a dual-mass structure for a MEMS gyroscope with amplitude amplification function according to the present invention. Figure 2 A schematic diagram of a four-mass structure for a MEMS gyroscope with amplitude amplification function according to the present invention. Wherein: 1a-anchor point, 1b-anchor point, 7a-mass block, 7b-mass block, 8a-x-axis rigid beam, 8b-x-axis rigid beam, 9a-y-axis rigid beam, 9b-y-axis rigid beam, 10a-drive coupling beam, 10b-drive coupling beam, 11-magnification detection beam, 12a-detection sensitive beam, 12b-detection sensitive beam, 13a-drive-detection decoupling beam, 13b-drive-detection decoupling beam, 14-detection beam, 15-detection beam, 20a-movable comb tooth, 20b-movable comb tooth, 24a-detection-drive decoupling beam, 24b-detection-drive decoupling beam, 21-movable comb tooth, 22-drive comb tooth, 23-drive detection comb tooth. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Example 1 like Figure 1 As shown, a MEMS gyroscope structure with amplitude amplification is disclosed. This structure includes a drive frame, two mass blocks, a drive structure, and a detection structure. The drive frame consists of x-axis rigid beams 8a and 8b, and y-axis rigid beams 9a and 9b connected to the left and right ends of the x-axis rigid beams 8a and 8b, respectively. The x-axis rigid beams 8a and 8b are fixed to anchor points. The y-axis rigid beams 9a and 9b connect to two mass blocks 7a and 7b, respectively. The x-axis rigid beams 8a and 8b are rigid in the x-axis direction and do not easily deform when force is applied in that direction, exhibiting only compression and elongation. However, they are flexible in the y-axis direction, deforming when force is applied. Similarly, the y-axis rigid beams 9a and 9b are flexible in the x-axis direction but rigid in the y-axis direction.

[0022] The driving structure includes detection-drive decoupling beams 24a and 24b and multiple sets of comb tooth structures. Detection-drive decoupling beams 24a and comb tooth structures are connected to the y-axis rigid beam 9a and distributed on both sides of the mass block 7a. Detection-drive decoupling beams 24b and comb tooth structures are connected to the y-axis rigid beam 9b and symmetrically distributed on both sides of the mass block 7b. Detection-drive decoupling beams 24a and 24b are symmetrical about the y-axis rigid beams 9a and 9b, respectively, and their endpoints are fixed to anchor points. Each set of comb tooth structures consists of movable comb teeth 21, driving comb teeth 22, and driving detection comb teeth 23, and is connected to the y-axis rigid beams 9a and 9b of the driving frame through the movable comb teeth 21. The detection structure includes an elliptical magnifying detection beam 11, detection sensitive beams 12a and 12b, drive-detection decoupling beams 13a and 13b, detection beam 14, detection beam 15, and multiple sets of comb tooth structures. Specifically: two mass blocks 7a and 7b are connected to the top of the major semi-axis of the elliptical ring of the elliptical magnifying detection beam 11 via the two detection sensitive beams 12a and 12b, respectively; each set of comb tooth structures includes movable comb teeth, coupled to the top of the minor semi-axis of the elliptical ring of the elliptical magnifying detection beam 11; detection beams 14 and 15 are connected to movable comb teeth 20a and 20d in the comb tooth structure, respectively, and their endpoints are fixed to anchor points; drive-detection decoupling beams 13a and 13b are connected to detection sensitive beams 12a and 12b, respectively, and their endpoints are fixed to anchor points; in the detection mode, the mass blocks are coupled to each other via detection sensitive beams 12a and 12b, magnifying detection beam 11, and detection beams 14 and 15.

[0023] The working principle of the gyroscope in this embodiment is as follows: In this embodiment, the drive frame, as the main motion-bearing structure, performs in-plane reciprocating motion. Its motion principle is achieved by applying voltages of the same amplitude but opposite phase to the drive comb 22, thereby generating electrostatic forces in opposite directions. Under the action of electrostatic forces, the entire structure of the in-plane gyroscope resonates in the drive mode. When the entire structure resonates in the drive mode, the drive frame drives the mass block to also resonate. At this time, the adjacent mass blocks move in opposite directions. At the same time, the drive detection comb 23 can provide real-time feedback on the vibration state (frequency, phase, amplitude) of the mass block, enabling the drive system to start and maintain stable self-excited oscillation, keeping the vibration amplitude constant, thereby ensuring the stability of the generated Coriolis force and ensuring measurement accuracy.

[0024] Under a fixed driving mode frequency, if an external angular velocity is input, the mass block will generate a Coriolis force in the detection direction. Since adjacent mass blocks in the driving mode move in opposite directions, under the action of the Coriolis force, the mass blocks in the detection mode also move in opposite directions (according to the right-hand rule), generating left-right motion in the detection direction. This provides a basis for using differential detection technology, thereby amplifying the useful signal and suppressing common-mode interference. During the vibration of the elliptical amplification detection beam 11, the displacement of the mass block (along the minor axis of the central ellipse) is coupled to the displacement of the sensitive comb teeth (along the minor axis of the combined elliptical beam, parallel to the driving displacement direction). When the central elliptical ring reaches the resonant state, its maximum amplitude along the major and minor axes is approximated by the following formula: Ymax / Xmax = b / a; In the formula, b represents the major semi-axis, a represents the minor semi-axis, Ymax is the maximum displacement of the major semi-axis, and Xmax is the maximum displacement of the minor semi-axis, meaning the displacement of the major semi-axis is amplified by a factor of b / a. Under a fixed driving modal frequency, if an external angular velocity is input, the mass block will generate a Coriolis force in the detection direction. Under the action of the Coriolis force, the mass block will move in the detection direction. When the mass block is displaced under the action of the Coriolis force, the position of the moving comb tooth relative to the fixed comb tooth changes, resulting in a change in capacitance. This change in capacitance is converted into a voltage or current signal by a capacitance sensor and then processed by signal processing circuits (such as amplifiers, filters, analog-to-digital converters, etc.). Finally, the input angular velocity is calculated using a digital signal processing algorithm. During this process, due to the displacement coupling between the central elliptical ring and the sensitive comb tooth, and its amplifying effect, the vibration displacement of the sensitive comb tooth also increases by a factor of b / a, improving detection sensitivity and thus enhancing the gyroscope's zero-bias stability.

[0025] Furthermore, since the driving structure, detection structure, and mass block are independent of each other, the driving structure is restricted by the driving frame lever detection-driving decoupling beam and can only move along the driving direction. The detection structure is restricted by its supporting structure and the driving-detection decoupling beam and can only move along the detection direction. The mass block has two degrees of freedom in the plane, thus achieving decoupling. At the same time, the size of the key flexible beam is systematically adjusted rather than the topology is changed, the frequency of the driving mode and the detection mode is tuned to the first three orders of the system, and the frequency of the main parasitic mode is pushed to the fourth order or higher, thereby eliminating the parasitic mode between the driving mode and the sensitive mode. The driving mode and the detection mode can achieve the decoupling effect.

[0026] Example 2 like Figure 2 As shown, compared with Embodiment 1, the MEMS gyroscope structure with amplitude amplification provided in this embodiment is different in that it includes two groups of four mass blocks, two driving structures and a detection structure, and also includes driving coupling beams 10a and 10b respectively installed on rigid beams 9a and 9b on the y-axis and located between each group of mass blocks, and the detection structure of each group is connected by beam 25.

[0027] The working principle of the gyroscope structure in this embodiment is the same as that in Embodiment 1. In addition, it has the following technical effects: The four-mass block structure adopted in this embodiment has the advantage of decoupling the driving mode and the detection mode due to the use of a large-area sensitive mass block. At the same time, it also has a large signal output gain, which further improves the detection accuracy.

[0028] Example 3 Compared with Embodiments 1 and 2, the MEMS gyroscope structure with amplitude amplification provided in this embodiment differs in that, based on Embodiments 1 and 2, the driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the x-axis.

[0029] Example 4 Compared with Embodiments 1, 2, and 3, the MEMS gyroscope structure with amplitude amplification provided in this embodiment differs in that, based on Embodiments 1, 2, and 3, the driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the y-axis.

[0030] Example 5 Compared to Example 4, the MEMS gyroscope structure with amplitude amplification provided in this example differs in that: the x-axis rigid beams 8a and 8b are fixed at anchor points 1a and 1b at the center of the drive frame and are connected by short beams. The detection-drive decoupling beams 24a and 24b, detection beams 14 and 15, and drive-detection decoupling beams 13a and 13b are fixed at the anchor points at the two ends of the beams.

[0031] The gyroscope structures provided in Examples 3, 4, and 5 also have the following technical effects: they adopt a symmetrical structure, which enables differential detection, and the same external interference is processed differentially, further ensuring sensitivity and anti-interference ability; and the symmetrical structure can effectively suppress manufacturing errors, thereby improving the stability of the gyroscope.

[0032] It should be noted that in the above embodiments, the circle is one type of ellipse. When the magnified detection beam 11 is a circle, the displacement is magnified by 1 time, but it is still within the protection scope of this application.

Claims

1. A MEMS gyroscope structure with amplitude amplification function, comprising a drive frame and at least one set of two mass blocks, a drive structure, and a detection structure, characterized in that: The drive frame consists of an x-axis rigid beam (8a) and (8b) and a y-axis rigid beam (9a) and (9b) connected to the left and right ends of the x-axis rigid beam (8a) and (8b) respectively. The x-axis rigid beam (8a) and (8b) drive the frame to be fixed on the anchor point; the y-axis rigid beam (9a) and (9b) are connected to two mass blocks (7a) and (7b) respectively. The driving structure includes a detection-drive decoupling beam (24a) and (24b) and multiple sets of comb tooth structures. The detection-drive decoupling beam (24a) and comb tooth structures are connected to the y-axis rigid beam (9a) and distributed on both sides of the mass block (7a). The detection-drive decoupling beam (24b) and comb tooth structures are connected to the y-axis rigid beam (9b) and symmetrically distributed on both sides of the mass block (7b). The detection-drive decoupling beams (24a) and (24b) are symmetrical about the y-axis rigid beams (9a) and (9b) and fixed at the anchor point. Each set of comb tooth structures consists of movable comb teeth (21), driving comb teeth (22) and driving detection comb teeth (23). The movable comb teeth (21) are connected to the y-axis rigid beams (9a) and (9b) of the driving frame. The detection structure includes an elliptical magnifying detection beam (11), detection sensitive beams (12a) and (12b), a drive-detection decoupling beam (13a) and (13b), a detection beam (14), a detection beam (15), and multiple sets of comb tooth structures, wherein: two mass blocks (7a) and (7b) are respectively connected to the top of the major semi-axis of the elliptical ring of the elliptical magnifying detection beam (11) through two detection sensitive beams (12a) and (12b); each set of comb tooth structures includes movable comb teeth and fixed comb teeth, the movable comb teeth being connected to the elliptical magnifying detection beam (11) through the drive-detection decoupling beam (13a) and (13b). The top of the short semi-axis of the elliptical ring is connected and coupled. The movable comb teeth and the fixed comb teeth are staggered along the detection motion direction and do not contact each other. The detection beam (14) and the detection beam (15) are respectively connected to the movable comb teeth in the comb tooth structure and fixed to the anchor point. The drive-detection decoupling beams (13a) and (13b) are respectively connected to the detection sensitive beams (12a) and (12b) and fixed to the anchor point. The mass block in the detection mode is coupled to each other through the detection sensitive beams (12a) and (12b), the amplified detection beam (11), and the detection beams (14) and (15).

2. The MEMS gyroscope structure with amplitude amplification function as described in claim 1, characterized in that: When the two mass blocks, driving structure, and detection structure are more than one set, the system also includes driving coupling beams (10a) and (10b) respectively installed on rigid beams (9a) and (9b) on the y-axis and located between each set of mass blocks, and the detection structures of each set are connected by beams (25).

3. The MEMS gyroscope structure with amplitude amplification function as described in claim 2, characterized in that: The adjacent mass blocks move in opposite directions.

4. The MEMS gyroscope structure with amplitude amplification function as described in claim 3, characterized in that: The driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the x-axis.

5. A MEMS gyroscope structure with amplitude amplification function as described in claim 1, 2, or 3, characterized in that: The driving frame, mass block, driving structure, and detection structure are arranged symmetrically about the y-axis.

6. A MEMS gyroscope structure with amplitude amplification function as described in claim 5, characterized in that: The x-axis rigid beams (8a) and (8b) are fixed at anchor points (1a) and (1b) at the center of the driving frame and are connected to the anchor points by short beams.

7. A MEMS gyroscope structure with amplitude amplification function as described in claim 6, characterized in that: The detection-drive decoupling beams (24a) and (24b), the detection beam (14), the detection beam (15), and the drive-detection decoupling beams (13a) and (13b) are fixed at the anchor points at the two ends of the beams.

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