Asymmetric coupling stiffness disturbance type MEMS modal localization accelerometer and detection method

Abstract

The invention discloses an asymmetric coupling rigidity disturbance type MEMS modal localization accelerometer and a detection method. The accelerometer comprises an upper signal conversion layer and a lower glass substrate layer. The upper signal conversion layer comprises a sensitive mass block, a supporting structure and asymmetrical coupled resonator pairs which are symmetrically distributed. According to the asymmetric coupling resonator pair, a first type resonator and a second type resonator form a weak coupling system through electrostatic coupling, the first type resonator is fixed to a glass substrate layer through anchor points, the second type resonator is fixed to a sensitive mass block, and the first type resonator and the second type resonator meet the mass and rigidity asymmetric relation. When being subjected to the acceleration effect, the sensitive mass block generates micro displacement, changes the static coupling rigidity and triggers the modal localization effect, so that the amplitude ratio of the two resonators is changed, and acceleration measurement is realized by detecting the amplitude ratio change. By adopting the asymmetric structure, the sensitivity of the accelerometer is doubled compared with that of a symmetric structure, and meanwhile, the accelerometer has good linearity and anti-interference capability.

Description

Technical Field

[0001] This invention relates to the fields of microelectromechanical systems (MEMS) and microinertial measurement technology, and particularly to an asymmetric coupled stiffness perturbation-type MEMS modal localization accelerometer and its detection method. Background Technology

[0002] With the advancement of microelectromechanical systems (MEMS) technology, modal localization sensors based on weakly coupled resonators have become an important research direction due to their potential for ultra-high sensitivity in the field of inertial sensing. Unlike traditional resonant accelerometers that rely on frequency shift detection, these sensors sense physical quantities by monitoring changes in the amplitude ratio of the weakly coupled resonant system under disturbances, theoretically improving detection sensitivity by one to three orders of magnitude.

[0003] Early modal localization sensors primarily employed mass perturbation or stiffness perturbation mechanisms. For example, this was achieved by adding a sensitive mass block to the resonator or designing a support structure with acceleration-sensitive characteristics to alter the resonator's equivalent mass or stiffness parameters. While these methods utilized modal localization to some extent, their performance was severely limited by modal aliasing effects: when external perturbations increased, strong interactions or even interchanges occurred between the characteristic modes of the weakly coupled system, leading to a decrease, saturation, or reversal in the rate of change of the amplitude ratio, thus limiting the sensor's maximum mechanical sensitivity and linear operating range.

[0004] To address the aforementioned problems, existing research has proposed a technical approach of coupled stiffness perturbation. This approach transforms the inertial micro-displacement caused by external acceleration into a change in the coupled stiffness of a weakly coupled system, and achieves signal output based on amplitude ratio detection. This method suppresses mode mixing to some extent and improves sensitivity and linearity. However, existing coupled stiffness perturbation structures are mostly based on symmetrical resonator designs, and their sensitivity improvement is still limited by the structural symmetry, making it difficult to achieve a wider range of linear extensions. Furthermore, the symmetrical configuration is more sensitive to manufacturing process deviations and fluctuations in the operating environment, affecting the stability and consistency of the sensor. Summary of the Invention

[0005] Purpose of the Invention: The purpose of this invention is to provide an asymmetric coupled stiffness perturbation-based MEMS modal localization accelerometer and detection method. Through the design of an asymmetric resonator and a coupled stiffness perturbation mechanism, the modal localization effect is effectively utilized to achieve an acceleration detection sensitivity approximately [missing information - likely a percentage] higher than that of symmetric structures. This represents a significant improvement of several times, while also extending the linear operating range of the accelerometer and enhancing its anti-interference capabilities.

[0006] Technical Solution: An asymmetric coupled stiffness perturbation-type MEMS modal localization accelerometer includes an upper signal conversion layer and a lower glass substrate layer. The upper signal conversion layer includes a sensitive mass block, a support structure for supporting and guiding the sensitive mass block to move along the X-axis, and at least one pair of asymmetric coupled resonators symmetrically distributed on both sides of the central axis of the sensitive mass block. The asymmetric coupled resonator pair forms a weakly coupled resonant system by electrostatic coupling of a first type of resonator and a second type of resonator. The upper and lower ends of the first type of resonator are directly fixed to the lower glass substrate layer through anchor points, and its effective mass and support stiffness are respectively... and The upper and lower ends of the second type of resonator are directly fixed to the sensitive mass block, and its effective mass and support stiffness are respectively... and The first type of resonator and the second type of resonator satisfy an asymmetric relationship: , ,in, The ratio of the effective mass of the first type of resonator to that of the second type of resonator is given. >1; The lower glass substrate layer provides full constraint support for the first type of resonator, as well as base support for the support structure and external circuitry, providing electrical pathways for the driving and sensing structures on the first and second types of resonators. When acceleration along the X-axis is applied to the accelerometer, the sensitive mass block generates inertial micro-displacement, thereby changing the electrostatic coupling stiffness of the weakly coupled resonant system and causing a change in the amplitude ratio between the first and second types of resonators. The acceleration value is calculated by detecting the change in the amplitude ratio.

[0007] Furthermore, the support structure is in the form of a frame, including a swing suppression frame, a first-direction elastic beam, a second-direction elastic beam, a first elastic beam support end, a second elastic beam support end, a first elastic beam fixed end, a second elastic beam fixed end, a first-direction decoupling structure, a second-direction decoupling structure, a third-direction decoupling structure, and a fourth-direction decoupling structure; wherein, the stiffness of each elastic beam and each decoupling structure in the X-axis direction is much smaller than its stiffness in the Y-axis and Z-axis directions; The first directional elastic beam and the second directional elastic beam have the same structure and are respectively set on the left and right edges of the sensitive mass block; the side of the first directional elastic beam close to the sensitive mass block is connected through the first elastic beam support end, and the side of the second directional elastic beam close to the sensitive mass block is connected through the second elastic beam support end; the side of the first directional elastic beam away from the sensitive mass block is fixed through the first elastic beam fixing end, and the side of the second directional elastic beam away from the sensitive mass block is fixed through the second elastic beam fixing end. The first, second, third, and fourth directional decoupling structures are symmetrically arranged around the sensitive mass block with the central axis of the sensitive mass block as the axis of symmetry. The first and second directional decoupling structures are located on the upper left and right sides, while the third and fourth directional decoupling structures are located on the lower right and left sides. One end of each directional decoupling structure is connected to the sensitive mass block, and the other end is directly fixed to the swing suppression frame.

[0008] Furthermore, a pair of asymmetric coupled resonators includes a first asymmetric coupled resonator pair and a second asymmetric coupled resonator pair with identical structures; The first asymmetric coupled resonator pair includes a first double-ended fixed tuning fork resonator and a first double-ended fixed beam resonator; wherein: The first double-ended fixed tuning fork resonator includes a tuning fork beam, a tuning fork beam comb structure, and a tuning fork beam electrostatic coupling parallel plate. The first double-ended fixed tuning fork resonator is fixed to the lower glass substrate layer through a first base anchor point and a second base anchor point. The tuning fork beam is composed of two parallel beams with the same structure, and the tuning fork beam comb structure is connected to both sides. The tuning fork beam comb structure includes an outer comb support cantilever, an inner comb support cantilever, a first drive comb and a second drive comb on the side away from the tuning fork beam, and a first detection comb and a second detection comb on the side closer to the tuning fork beam. The inner comb tooth support cantilever of the tuning fork beam is connected to the electrostatic coupling parallel plate of the tuning fork beam. The first drive comb teeth and the comb teeth on the right side of the outer comb tooth support cantilever of the tuning fork beam are interlocked to form the first drive comb tooth group; The second drive comb teeth interlock with the comb teeth on the left side of the inner comb tooth support cantilever of the tuning fork beam to form the second drive comb tooth group. The first double-ended fixed beam resonator includes a fixed single beam, a fixed single beam comb structure, and a fixed single beam electrostatic coupling parallel plate. The fixed single beam is a single beam structure with the fixed single beam comb structure connected to both sides. The fixed single beam comb structure includes an outer comb support cantilever, an inner comb support cantilever, and a third and fourth drive comb on the side away from the fixed single beam. There are also a third and fourth detection comb on the side closer to the fixed single beam. The inner comb support cantilever is connected to the fixed single beam electrostatic coupling parallel plate. The third drive comb and the comb on the left side of the outer comb support cantilever are interleaved to form the third drive comb group. The fourth drive comb tooth and the comb tooth on the right side of the cantilever supported by the comb tooth in the fixed single beam are interlocked to form the fourth drive comb tooth group. The first detection comb teeth and the comb teeth on the left side of the outer comb tooth support cantilever of the tuning fork beam are interlocked to form the first detection comb tooth group; The second detection comb teeth interlock with the comb teeth on the right side of the inner comb tooth support cantilever of the tuning fork beam, forming the second detection comb tooth group; The third detection comb teeth interlock with the comb teeth on the right side of the cantilever supported by the outer comb teeth of the fixed single beam, forming the third detection comb tooth group; The fourth detection comb teeth interlock with the comb teeth on the left side of the cantilever supported by the comb teeth inside the fixed single beam, forming the fourth detection comb tooth group; An antiphase AC signal is applied to the first and second drive comb groups, and an antiphase AC signal is applied to the third and fourth drive comb groups, so as to drive the first double-ended fixed tuning fork resonator and the first double-ended fixed beam resonator to vibrate at their natural frequencies and operate in antiphase working modes.

[0009] Furthermore, the electrostatic coupling parallel plate of the tuning fork beam and the electrostatic coupling parallel plate of the fixed single beam are placed parallel to each other to form the electrostatic coupling part of the weakly coupled resonant system; the electrostatic coupling stiffness is determined by the following formula: , , The negative sign indicates the negative stiffness characteristic of electrostatic coupling. Indicates electrostatic coupling stiffness; This represents the micro-displacement of a fixed single-beam electrostatically coupled parallel plate caused by acceleration. The overlapping area of ​​the electrostatic coupling parallel plate of the fixed single beam and the electrostatic coupling parallel plate of the tuning fork beam; The initial spacing between the fixed single-beam electrostatic coupling parallel plate and the tuning fork beam electrostatic coupling parallel plate; To apply the difference in bias voltage between the fixed single-beam electrostatic coupling parallel plate and the tuning fork beam electrostatic coupling parallel plate; It is the dielectric constant; Indicates the gain of the micro-displacement and acceleration conversion. The input acceleration; Under small displacement conditions, At the initial spacing Perform a first-order Taylor expansion at this point: , Amplitude ratio of asymmetric coupled resonators The theoretical expression is: , in, This refers to the equivalent stiffness disturbance introduced by the asymmetric structure. When the acceleration along the positive X-axis When applied to the system, the sensitive mass block is displaced; since the first asymmetric coupled resonator pair and the second asymmetric coupled resonator pair are symmetrically distributed on both sides of the sensitive mass block, this displacement will cause the electrostatic coupling plate spacing of the resonator pair on one side to decrease, while the spacing on the other side will increase. The amplitude ratio of the first asymmetric coupled resonator pair to the second asymmetric coupled resonator pair is differentially processed to obtain the final differential detection signal. With acceleration Relationship: , Among them, differential detection signal It is the difference between the amplitude ratio of the first asymmetric coupled resonator pair and the amplitude ratio of the second asymmetric coupled resonator pair; further, The value range is greater than 1 and does not exceed 3.

[0010] A detection method for an asymmetric coupled stiffness perturbation type MEMS modal localization accelerometer, used to process the detection signal of any of the above-mentioned accelerometers, includes the following steps: S1, performing differential processing on the signals output by the detection structures on both sides of the first type of resonator to obtain a first amplitude detection signal. The signals output from the detection structures on both sides of the second type of resonator are differentially processed to obtain the second amplitude detection signal. S2, the first amplitude detection signal of the asymmetric resonator on the same side. With the second amplitude detection signal Calculate the ratio to obtain the amplitude ratio signal on that side. = / S3, differentiate the amplitude ratio signals on both sides of the central axis of the sensitive mass block, and output the final differential detection signal. Based on the working principle of weakly coupled resonant systems, the differential detection signal... Acceleration .

[0011] Compared with the prior art, the significant advantages of this invention are as follows: 1. The accelerometer of the present invention uses an asymmetrically designed resonator to ( >1) By converting the inertial displacement caused by acceleration into an effective disturbance of coupling stiffness, the modal localization effect is significantly enhanced, enabling the sensor sensitivity to achieve approximately [a higher level] compared to traditional symmetrical structures. A significant improvement of several times; 2. The accelerometer of the present invention utilizes an asymmetric structure combined with a coupling stiffness perturbation mechanism to effectively suppress mode aliasing, expand the linear response range between amplitude ratio and acceleration, and improve the measurement accuracy and reliability under large dynamic input conditions. 3. The accelerometer of the present invention optimizes the motion guidance and constraint of the sensitive mass block by setting up a swing suppression frame, a directional elastic beam and a decoupling structure, enhances the anti-interference ability of the structure in non-sensitive directions, reduces cross-coupling error and improves overall stability. 4. The detection method of the present invention adopts a differential amplitude ratio detection and signal processing method, which effectively suppresses interference such as common mode noise and temperature drift, improves the signal-to-noise ratio of the output signal, and enables the accelerometer to maintain high accuracy and good consistency in complex environments. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the upper signal conversion layer structure of the present invention; Figure 3 This is a schematic diagram of the support structure of the present invention; Figure 4 This is a schematic diagram of the structure of a single asymmetric coupled resonator pair of the present invention; Figure 5 This is a schematic diagram of the sensitive mass block structure of the present invention; Figure 6 This is a schematic diagram of the swing suppression frame structure of the present invention; Figure 7 This is a schematic diagram of the initial spacing d in the weakly coupled resonant system of the present invention; Figure 8 This is a schematic diagram of the first double-ended fixed beam resonator structure of the present invention and the area A of its electrostatic coupling parallel plate. Figure 9 This is a schematic diagram of the first double-ended fixed tuning fork resonator structure of the present invention and the area A of its electrostatic coupling parallel plate; Figure 10 This is a schematic diagram of the first drive comb tooth structure of the present invention; Figure 11 This is a schematic diagram of the second detection comb structure of the present invention.

[0013] Figure labeling: 1: Upper signal conversion layer; 2: Sensitive mass block; 3: Support structure; 4: First asymmetric coupled resonator pair; 5: Second asymmetric coupled resonator pair; 6: Lower glass substrate layer; 2-1: The central axis of the sensitive mass block; 3-1: First-direction decoupling structure; 3-2: Second-direction decoupling structure; 3-3: Third-direction decoupling structure; 3-4: Fourth-direction decoupling structure; 3-5: First-direction elastic beam; 3-6: Second-direction elastic beam; 3-7: Fixed end of the first elastic beam; 3-8: Support end of the first elastic beam; 3-9: Fixed end of the second elastic beam; 3-10: Support end of the second elastic beam; 3-11: Swing suppression frame; 4-1: First double-ended fixed tuning fork resonator; 4-2: First double-ended fixed beam resonator; 5-1: Second double-ended fixed tuning fork resonator; 5-2: Second double-ended fixed beam resonator; 4-1-1: Tuning fork beam; 4-1-2: Electrostatic coupling parallel plate of tuning fork beam; 4-1-3: Inner comb tooth support cantilever of tuning fork beam; 4-1-4: Outer comb tooth support cantilever of tuning fork beam; 4-1-5: First driving comb tooth; 4-1-6: Second driving comb tooth; 4-1-7: First detection comb tooth; 4-1-8: Second detection comb tooth; 4-1-9: First base anchor point; 4-1-10: Second base anchor point; 4-2-1: Fixed single beam; 4-2-2: Fixed single beam electrostatic coupling parallel plate; 4-2-3: Fixed single beam inner comb tooth supported cantilever; 4-2-4: Fixed single beam outer comb tooth supported cantilever; 4-2-5: Third drive comb tooth; 4-2-6: Fourth drive comb tooth; 4-2-7: Third detection comb tooth; 4-2-8: Fourth detection comb tooth. Detailed Implementation

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0015] This invention proposes an asymmetric coupled stiffness perturbation-based MEMS modal localization accelerometer for measuring the acceleration of a carrier relative to inertial space. The accelerometer is as follows... Figure 1 As shown, it includes an upper signal conversion layer 1 and a lower glass substrate layer 6. The upper signal conversion layer 1 includes a sensitive mass block 2, a support structure 3 for supporting and guiding the sensitive mass block 2 to move along the X-axis, and at least one pair of asymmetric coupled resonators symmetrically distributed on both sides of the central axis 2-1 of the sensitive mass block.

[0016] In this embodiment, two pairs of asymmetric coupled resonators are preferably provided: a first asymmetric coupled resonator pair 4 located to the left of the central axis 2-1 of the sensitive mass block, and a second asymmetric coupled resonator pair 5 located to the right. Each asymmetric coupled resonator pair consists of a first-type resonator and a second-type resonator forming a weakly coupled resonant system through electrostatic coupling. The lower glass substrate layer 6 provides full-constraint support for the first-type resonators and also provides substrate support for the support structure 3; it also connects to external circuits, providing electrical pathways for the driving and detection structures on the first and second-type resonators.

[0017] like Figure 2As shown, in this embodiment, the first asymmetric coupling resonator pair 4 includes a first type of resonator and a second type of resonator; the first type of resonator is a first double-ended fixed tuning fork resonator 4-1, which is arranged on the side close to the central axis 2-1 of the sensitive mass block, and its upper and lower ends are respectively fixed to the lower glass substrate layer 6 through anchor points; the second type of resonator is a first double-ended fixed beam resonator 4-2, which is arranged on the side away from the central axis 2-1 of the sensitive mass block, and its upper and lower ends are directly fixed to the sensitive mass block 2.

[0018] The second asymmetric coupled resonator pair 5 also includes a first type of resonator and a second type of resonator; the first type of resonator is a second double-ended fixed tuning fork resonator 5-1, which is arranged on the side close to the central axis 2-1 of the sensitive mass block, and its upper and lower ends are respectively fixed to the lower glass substrate layer 6 through anchor points; the second type of resonator is a second double-ended fixed beam resonator 5-2, which is arranged on the side away from the central axis 2-1 of the sensitive mass block, and its upper and lower ends are directly fixed to the sensitive mass block 2.

[0019] The effective mass of the first double-ended fixed tuning fork resonator 4-1 and the second double-ended fixed tuning fork resonator 5-1 is both The support stiffness is The effective mass of the first double-ended fixed beam resonator 4-2 and the second double-ended fixed beam resonator 5-2 are both The support stiffness is .

[0020] In each asymmetric coupled resonator pair, the first type of resonator and the second type of resonator satisfy a predetermined asymmetric relationship, specifically: the effective mass of the first type of resonator... The effective mass of a type II resonator of The support stiffness of the first type of resonator is times that of the first type. Support stiffness for the second type of resonator of times ( >1), that is .

[0021] The value of N is greater than 1 and no more than 3, preferably between 1.5 and 2.5. This preferred range takes into account the balance between enhancing modal localization effects and the feasibility of structural fabrication: when N approaches 1, the system structure tends to be symmetrical, limiting the improvement in sensitivity; while when N exceeds 3, although theoretically sensitivity can still be improved, excessive asymmetry will exacerbate the localization of modal energy, causing the amplitude ratio response curve to enter the saturation region prematurely, thus compressing the linear measurement range of the accelerometer. Furthermore, a larger N value places higher demands on the consistency control of micro / nano fabrication processes, potentially affecting the matching accuracy and overall performance stability of the resonator pair. Therefore, setting the N value preferably between 1.5 and 2.5 allows for a significant improvement in sensitivity while maintaining good linear response characteristics, structural stability, and fabrication feasibility.

[0022] The aforementioned asymmetric relationship can be achieved by adjusting the structural dimensions, material properties, or topology of the first and second type of resonators. Specifically, regarding structural dimensions, the length, width, and thickness of the core vibration beam of the two types of resonators can be differentiated using micro-nano fabrication processes, or the dimensions and number of their associated driving or sensing combs, support cantilevers, and electrostatic coupling parallel plates can be adjusted to directly and precisely control their effective mass and support stiffness. Regarding material properties, materials with different Young's moduli and densities (e.g., silicon carbide for the first type of resonator and polycrystalline silicon for the second type) can be selected to fabricate the two types of resonators, or selective doping of the same base material (such as monocrystalline silicon) can introduce an inherent parameter mismatch. Regarding topology, in addition to the combination of a double-ended fixed tuning fork (first type) and a double-ended fixed beam (second type) used in the embodiments, the asymmetric relationship can also be achieved by selecting other resonator configurations that physically ensure a proportional amplification of both mass and stiffness. For example, the first type of resonator can employ a resonator with a large central mass block and achieve high stiffness through short and thick support beams; while the second type of resonator uses a similar beam structure without an additional mass block or with a very small mass block to achieve significantly lower mass and stiffness references. By combining one or more of the above techniques, the required asymmetric scaling factor N can be achieved accurately and flexibly, thus ensuring that the accelerometer achieves the expected performance improvement while also taking into account good process feasibility and design flexibility.

[0023] The first asymmetric coupled resonator pair 4 and the second asymmetric coupled resonator pair 5 form a differential structure, which can improve the scaling factor of the accelerometer, reduce common-mode interference, reduce temperature drift, and improve the sensitivity and linearity of the accelerometer.

[0024] Sensitive mass block 2 is uniformly supported by two-directional elastic beams and four-directional decoupling structures arranged in the support structure 3 surrounding it, forming a suspended mass block used to sense acceleration in the X-axis direction in the horizontal plane. The structure of sensitive mass block 2 is as follows: Figure 5 As shown.

[0025] like Figure 3 As shown, the support structure 3 is in the form of a frame, including a swing suppression frame 3-11, a first-direction elastic beam 3-5, a second-direction elastic beam 3-6, a first-direction elastic beam support end 3-8, a second-direction elastic beam support end 3-10, a first-direction elastic beam fixed end 3-7, a second-direction elastic beam fixed end 3-9, a first-direction decoupling structure 3-1, a second-direction decoupling structure 3-2, a third-direction decoupling structure 3-3, and a fourth-direction decoupling structure 3-4.

[0026] The first directional elastic beam 3-5 and the second directional elastic beam 3-6 have the same structure and are respectively set on the left and right edges of the sensitive mass block 2. The side of each directional elastic beam closest to the sensitive mass block 2 is connected to an elastic beam support end. Specifically, the first directional elastic beam 3-5 is connected through the first elastic beam support end 3-8, and the second directional elastic beam 3-6 is connected through the second elastic beam support end 3-10. The side of each directional elastic beam furthest from the sensitive mass block 2 is fixed through an elastic beam fixing end. Specifically, the first directional elastic beam 3-5 is fixed through the first elastic beam fixing end 3-7, and the second directional elastic beam 3-6 is fixed through the second elastic beam fixing end 3-9.

[0027] The first-direction decoupling structure 3-1, the second-direction decoupling structure 3-2, the third-direction decoupling structure 3-3, and the fourth-direction decoupling structure 3-4 are symmetrically arranged around the central axis 2-1 of the sensitive mass block. Specifically, the first-direction decoupling structure 3-1 and the second-direction decoupling structure 3-2 are located on the upper left and right sides, while the third-direction decoupling structure 3-3 and the fourth-direction decoupling structure 3-4 are located on the lower right and left sides. One end of each decoupling structure is connected to the sensitive mass block 2, and the other end is directly fixed to the swing suppression frame 3-11, the structure of which is as follows: Figure 6 As shown.

[0028] Through the above design, the stiffness of the first-direction elastic beam 3-5, the second-direction elastic beam 3-6, the first-direction decoupling structure 3-1, the second-direction decoupling structure 3-2, the third-direction decoupling structure 3-3, and the fourth-direction decoupling structure 3-4 in the X-axis direction is much smaller than their stiffness in the Y-axis and Z-axis directions. This stiffness characteristic enables the support structure 3 to respond sensitively to acceleration in the X-axis direction, while effectively suppressing the coupling error caused by acceleration in the Y-axis and Z-axis directions, thereby ensuring that the accelerometer has excellent X-axis direction detection characteristics and anti-interference ability.

[0029] like Figure 4 As shown, the first asymmetric coupled resonator pair 4 and the second asymmetric coupled resonator pair 5 are structurally identical. The following explanation will take the first asymmetric coupled resonator pair 4 as an example.

[0030] The first asymmetric coupled resonator pair 4 includes a first double-ended fixed tuning fork resonator 4-1 and a first double-ended fixed beam resonator 4-2. Wherein: The first double-ended fixed tuning fork resonator 4-1 includes a tuning fork beam 4-1-1, a tuning fork beam comb structure, a tuning fork beam electrostatic coupling parallel plate 4-1-2, and a first base anchor point 4-1-9 and a second base anchor point 4-1-10.

[0031] The first double-ended fixed beam resonator 4-2 includes a fixed single beam 4-2-1, a fixed single beam comb structure, and a fixed single beam electrostatic coupling parallel plate 4-2-2.

[0032] The tuning fork beam 4-1-1 consists of two parallel beams with identical structures, connected to the tuning fork beam comb tooth structure on both sides; the tuning fork beam comb tooth structure specifically includes the outer comb tooth support cantilever 4-1-4, the inner comb tooth support cantilever 4-1-3, and comb teeth respectively set on both sides of the two: On the side away from the tuning fork beam 4-1-1, a first drive comb tooth 4-1-5 and a second drive comb tooth 4-1-6 are arranged. The structure of the first drive comb tooth 4-1-5 is as follows: Figure 10 As shown; A first detection comb tooth 4-1-7 and a second detection comb tooth 4-1-8 are arranged on the side near the tuning fork beam 4-1-1. The structure of the second detection comb tooth 4-1-8 is as follows: Figure 11 As shown.

[0033] The inner comb tooth support cantilever 4-1-3 of the tuning fork beam is connected to the electrostatic coupling parallel plate 4-1-2 of the tuning fork beam.

[0034] The first double-ended fixed beam resonator 4-2 has a single beam 4-2-1 with a fixed single beam comb structure on both sides. The fixed-beam comb tooth structure specifically includes a fixed-beam outer comb tooth support cantilever 4-2-4, a fixed-beam inner comb tooth support cantilever 4-2-3, and comb teeth respectively set on both sides of the two: The third drive comb tooth 4-2-5 and the fourth drive comb tooth 4-2-6 are arranged on the side away from the fixed single beam 4-2-1; The third detection comb tooth 4-2-7 and the fourth detection comb tooth 4-2-8 are arranged on the side near the fixed single beam 4-2-1; The fixed single beam inner comb tooth support cantilever 4-2-3 is connected to the fixed single beam electrostatic coupling parallel plate 4-2-2.

[0035] The first drive comb tooth 4-1-5 interlocks with the comb tooth on the right side of the outer comb tooth support cantilever 4-1-4 of the tuning fork beam to form the first drive comb tooth group. The second drive comb tooth 4-1-6 interlocks with the comb tooth on the left side of the inner comb tooth support cantilever 4-1-3 of the tuning fork beam to form the second drive comb tooth group; The third drive comb tooth 4-2-5 interlocks with the comb tooth on the left side of the fixed single beam outer comb tooth support cantilever 4-2-4 to form the third drive comb tooth group. The fourth drive comb tooth 4-2-6 interlocks with the comb tooth on the right side of the cantilever 4-2-3 supported by the comb tooth in the fixed single beam, forming the fourth drive comb tooth group; The first detection comb tooth 4-1-7 is interlocked with the comb tooth on the left side of the outer comb tooth support cantilever 4-1-4 of the tuning fork beam to form the first detection comb tooth group, which is used to detect amplitude signals. The second detection comb tooth 4-1-8 interlocks with the comb tooth on the right side of the comb tooth support cantilever 4-1-3 inside the tuning fork beam to form the second detection comb tooth group, which is used to detect amplitude signals. The third detection comb tooth 4-2-7 and the comb tooth on the right side of the cantilever 4-2-4 supported by the outer comb tooth of the fixed single beam are interlocked to form the third detection comb tooth group, which is used to detect the amplitude signal. The fourth detection comb tooth 4-2-8 is interlocked with the comb tooth on the left side of the cantilever 4-2-3 supported by the comb tooth in the fixed single beam, forming the fourth detection comb tooth group, which is used to detect amplitude signals.

[0036] Anti-phase AC signals are applied to the first and second drive comb groups, and anti-phase AC signals are applied to the third and fourth drive comb groups to drive the first double-ended fixed tuning fork resonator 4-1 and the first double-ended fixed beam resonator 4-2 to vibrate at their natural frequencies and operate in anti-phase modes. In this mode, the stress generated by the vibration of the tuning fork beam 4-1-1 and the fixed single beam 4-2-1 can cancel each other out at their respective ends, thereby obtaining a high thermoelastic quality factor and effectively suppressing mechanical thermal noise in a high vacuum environment.

[0037] The first double-ended fixed tuning fork resonator 4-1 is fixed to the lower glass substrate layer 6 via the first base anchor point 4-1-9 and the second base anchor point 4-1-10; the upper and lower ends of the first double-ended fixed beam resonator 4-2 are directly connected to the sensitive mass block 2. The tuning fork beam electrostatic coupling parallel plate 4-1-2 and the fixed single beam electrostatic coupling parallel plate 4-2-2 are parallel to each other with an initial spacing d, together forming the electrostatic coupling part of the weakly coupled resonant system, as shown below. Figure 7 As shown.

[0038] When acceleration along the X-axis is applied to the accelerometer, the sensitive mass block 2 drives the first double-ended fixed beam resonator 4-2 to move through inertial micro-displacement, changing the initial spacing d in the weakly coupled resonant system, and thus changing the electrostatic coupling stiffness. Electrostatic coupling stiffness Determined by the following formula: (1) The negative sign indicates the negative stiffness characteristic of electrostatic coupling. This represents the micro-displacement of the fixed single-beam electrostatically coupled parallel plate 4-2-2 caused by acceleration; The overlapping area of ​​the fixed single-beam electrostatic coupling parallel plate 4-2-2 and the tuning fork beam electrostatic coupling parallel plate 4-1-2 is as follows: Figure 8 , Figure 9 As shown; To apply the difference in bias voltage between the fixed single beam electrostatic coupling parallel plate 4-2-2 and the tuning fork beam electrostatic coupling parallel plate 4-1-2; is the dielectric constant.

[0039] Micro-displacement of a fixed-support single-beam electrostatically coupled parallel plate 4-2-2 caused by acceleration The expression is: (2) in, Indicates the gain of the micro-displacement and acceleration conversion. The acceleration is the input.

[0040] Under the assumption of small displacement ( ),right At the initial spacing Perform a first-order Taylor expansion at this point: (3) Meanwhile, to ensure the stability of the vibration modes and avoid mode distortion, the structural parameters in this embodiment must also meet the minimum coupling stiffness condition, the expression of which is: (4) in, The equivalent stiffness disturbance introduced by the asymmetric structure is represented by k; k is the characteristic stiffness of the weakly coupled resonant system, used to characterize the overall stiffness level of the system in the coupled state, and its value is determined by the support stiffness. and Joint decision; This is the system quality factor.

[0041] Amplitude ratio of asymmetric coupled resonators The theoretical expression is: (5) in, , , For the effective mass of a type-1 resonator, For the effective mass of a type II resonator, Support stiffness of the first type of resonator This refers to the support stiffness of the second type of resonator.

[0042] According to the principle formula (1) of the present invention, the formula (5) is expanded by Taylor and the acceleration is... Taking the derivative, we can obtain the sensitivity. The formula is: = (6) When the acceleration along the positive X-axis When applied to a weakly coupled resonant system, the sensitive mass block undergoes displacement. Because the first asymmetric coupled resonator pair (left) and the second asymmetric coupled resonator pair (right) are symmetrically distributed on both sides of the sensitive mass block, this displacement... This will cause the electrostatic coupling plate spacing of one side of the resonator pair to decrease, while the spacing on the other side will increase. Let's set the left side spacing to... Then the right side spacing becomes .

[0043] According to formula (3), the electrostatic coupling stiffness on the left and right sides and They are respectively: (7) According to formula (4), the amplitude ratio of the left and right sides and They are respectively: (8) Differential detection signal is obtained by performing differential processing on the amplitude ratio of the left and right sides. The expression is: (9) At this point, the static bias terms cancel each other out, while the acceleration-related change terms are superimposed. According to formula (7), Substituting the expression into formula (9), we obtain the final output differential detection signal. With acceleration Explicit relationships: (10) in, This represents the initial electrostatic coupling stiffness (static bias term) without acceleration. This represents the change in electrostatic coupling stiffness.

[0044] The asymmetric structural design of this invention effectively suppresses mode aliasing by introducing inherent parameter mismatch. In symmetrically coupled systems, when external disturbances increase, the characteristic modes of the two resonators are prone to strong interaction or even interchange, leading to nonlinear saturation or reversal in the amplitude ratio response and limiting the linear operating range. However, the asymmetric structure, by setting an asymmetric ratio of mass and stiffness, ensures that the weakly coupled resonant system possesses inherent differences in modal energy distribution even when undisturbed. Therefore, under acceleration-induced coupling stiffness disturbances, the modal localization effect (i.e., the change in the amplitude ratio between the first and second type of resonators) is more stable, and the coupling strength between modes is controlled, avoiding mode transitions or aliasing. Combined with the coupling stiffness disturbance mechanism, the asymmetric design further reduces the system's sensitivity to disturbance amplitude, ensuring a linear relationship between amplitude ratio changes and acceleration over a larger dynamic range, thereby extending the sensor's linear response range and improving measurement reliability.

[0045] A detection method for an asymmetric coupled stiffness perturbation-type MEMS modal localization accelerometer, used for processing the detection signal, includes the following steps: Step 1, performing differential processing on the amplitude signals output from the first detection comb group and the second detection comb group to obtain the first amplitude detection signal. Step 2: Differential processing is performed on the amplitude signals output by the third and fourth detection comb groups to obtain the second amplitude detection signal. Step 3, the first amplitude detection signal With the second amplitude detection signal Calculate the ratio to obtain the amplitude ratio signal on that side. = / Step 4: Differentially process the amplitude ratio output by the first asymmetric coupled resonator pair 4 and the second asymmetric coupled resonator pair 5 to output the final differential detection signal. .

[0046] When acceleration in the X-axis direction is applied to the accelerometer, the inertial micro-displacement of the sensitive mass block 2 changes the electrostatic coupling stiffness of the weakly coupled resonant system, triggering a vibration mode localization effect, specifically manifested as a change in the amplitude ratio of the first type of resonator and the second type of resonator.

[0047] Therefore, by detecting the amplitude ratio of the first asymmetric coupled resonator pair 4 and the second asymmetric coupled resonator pair 5... and the amplitude ratio signal Differential processing is performed to obtain the final differential detection signal. Then, by combining the formula (10), the final acceleration value can be calculated.

[0048] Due to the special parameter settings of the asymmetric coupled resonator pair, namely >1, its amplitude ratio The theoretical expression formula (5) and the sensitivity formula (6) derived therefrom show that, under the condition that other parameters are completely consistent, the sensitivity of the accelerometer of the present invention can theoretically be approximately [value missing] higher than that of the symmetrical coupling structure. A multiple increase.

[0049] This invention provides an asymmetric coupled stiffness perturbation-based MEMS modal localization accelerometer and its detection method. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. An asymmetrically coupled stiffness perturbation MEMS modal localized accelerometer, comprising an upper signal conversion layer (1) and a lower glass substrate layer (6); the upper signal conversion layer (1) comprises a sensitive mass (2), a support structure (3) for supporting and guiding the sensitive mass (2) to move along the X-axis direction, and at least one pair of asymmetrically coupled resonators symmetrically distributed on both sides of the sensitive mass central axis (2-1); characterized in that: The asymmetric coupling resonator pair is a weak coupling resonator system formed by a first type of resonator and a second type of resonator through electrostatic coupling; the upper and lower ends of the first type of resonator are directly fixed to the lower glass substrate layer (6) through anchor points, and the effective mass and support stiffness thereof are and ; the upper and lower ends of the second type of resonator are directly fixed to the sensitive mass block (2), and the effective mass and support stiffness thereof are and ; the first type of resonator and the second type of resonator satisfy an asymmetric relationship: , wherein, is the ratio of the effective mass of the first type of resonator to the effective mass of the second type of resonator, and > 1; The lower glass substrate layer (6) is used to provide full-constraint support for the first type of resonator, and also used to provide base support for the support structure (3), and used to connect external circuit, and provide electrical access for driving structure and detection structure on the first type of resonator and the second type of resonator; when acceleration along the X-axis direction acts on the accelerometer, the sensitive mass (2) generates inertial micro-displacement, and then changes the electrostatic coupling stiffness of the weakly coupled resonant system, and causes the amplitude ratio of the first type of resonator and the second type of resonator to change, and the acceleration value is calculated by detecting the change amount of the amplitude ratio.

2. The asymmetrically coupled stiffness-perturbed MEMS modal localized accelerometer of claim 1, wherein, The support structure (3) is in the form of a frame, including a swing suppression frame (3-11), a first direction elastic beam (3-5), a second direction elastic beam (3-6), a first elastic beam support end (3-8), a second elastic beam support end (3-10), a first elastic beam fixed end (3-7), a second elastic beam fixed end (3-9), and a first direction decoupling structure (3-1), a second direction decoupling structure (3-2), a third direction decoupling structure (3-3), and a fourth direction decoupling structure (3-4); wherein the stiffness of each direction elastic beam and each direction decoupling structure in the X-axis direction is much smaller than the stiffness thereof in the Y-axis and Z-axis directions; The first direction elastic beam (3-5) and the second direction elastic beam (3-6) are structurally identical, and are respectively arranged on the left and right side edges of the sensitive mass (2); the side of the first direction elastic beam (3-5) close to the sensitive mass (2) is connected through the first elastic beam support end (3-8), and the side of the second direction elastic beam (3-6) close to the sensitive mass (2) is connected through the second elastic beam support end (3-10); the side of the first direction elastic beam (3-5) away from the sensitive mass (2) is fixed through the first elastic beam fixed end (3-7), and the side of the second direction elastic beam (3-6) away from the sensitive mass (2) is fixed through the second elastic beam fixed end (3-9); The first direction decoupling structure (3-1), the second direction decoupling structure (3-2), the third direction decoupling structure (3-3), and the fourth direction decoupling structure (3-4) are symmetrically arranged around the sensitive mass with the sensitive mass central axis (2-1) as the symmetry axis; wherein the first direction decoupling structure (3-1) and the second direction decoupling structure (3-2) are located on the upper left and right sides, and the third direction decoupling structure (3-3) and the fourth direction decoupling structure (3-4) are located on the lower right and left sides; one end of each direction decoupling structure (3-1) is connected with the sensitive mass (2), and the other end is directly fixed to the swing suppression frame (3-11).

3. The asymmetrically coupled stiffness-perturbed MEMS modal localized accelerometer of claim 1, wherein, The pair of asymmetrically coupled resonators includes a first pair of asymmetrically coupled resonators (4) and a second pair of asymmetrically coupled resonators (5) which are structurally identical; The first pair of asymmetrically coupled resonators (4) includes a first double-end fixed tuning fork resonator (4-1) and a first double-end fixed beam resonator (4-2); wherein: The first double-end fixed tuning fork resonator (4-1) comprises a tuning fork beam (4-1-1), a tuning fork beam comb structure, and a tuning fork beam electrostatic coupling parallel plate (4-1-2); the first double-end fixed tuning fork resonator (4-1) is fixed on the lower glass substrate layer (6) through a first base anchor point (4-1-9) and a second base anchor point (4-1-10); The tuning fork beam (4-1-1) is composed of two parallel beams with the same structure, and the two sides of the tuning fork beam are connected with the tuning fork beam comb structure; the tuning fork beam comb structure comprises a tuning fork beam outer comb support cantilever (4-1-4), a tuning fork beam inner comb support cantilever (4-1-3), a first driving comb (4-1-5) and a second driving comb (4-1-6) away from one side of the tuning fork beam (4-1-1), and a first detection comb (4-1-7) and a second detection comb (4-1-8) close to one side of the tuning fork beam (4-1-1); The tuning fork beam inner comb support cantilever (4-1-3) is connected with the tuning fork beam electrostatic coupling parallel plate (4-1-2); The first driving comb (4-1-5) and the comb on the right side of the tuning fork beam outer comb support cantilever (4-1-4) are staggered and inserted to form a first driving comb group; The second driving comb (4-1-6) and the comb on the left side of the tuning fork beam inner comb support cantilever (4-1-3) are staggered and inserted to form a second driving comb group; The first double-end fixed beam resonator (4-2) comprises a fixed single beam (4-2-1), a fixed single beam comb structure, and a fixed single beam electrostatic coupling parallel plate (4-2-2); the fixed single beam (4-2-1) is a single beam structure, and the two sides of the fixed single beam are connected with the fixed single beam comb structure; the upper and lower ends of the first double-end fixed beam resonator (4-2) are directly connected with the sensitive mass block (2); The fixed single beam comb structure comprises a fixed single beam outer comb support cantilever (4-2-4), a fixed single beam inner comb support cantilever (4-2-3), a third driving comb (4-2-5) and a fourth driving comb (4-2-6) away from one side of the fixed single beam (4-2-1), and a third detection comb (4-2-7) and a fourth detection comb (4-2-8) close to one side of the fixed single beam (4-2-1); the fixed single beam inner comb support cantilever (4-2-3) is connected with the fixed single beam electrostatic coupling parallel plate (4-2-2); the third driving comb (4-2-5) and the comb on the left side of the fixed single beam outer comb support cantilever (4-2-4) are staggered and inserted to form a third driving comb group; The fourth driving comb (4-2-6) and the comb on the right side of the fixed single beam inner comb support cantilever (4-2-3) are staggered and inserted to form a fourth driving comb group; The first detection comb (4-1-7) and the comb on the left side of the tuning fork beam outer comb support cantilever (4-1-4) are staggered and inserted to form a first detection comb group; The second detection comb (4-1-8) and the comb on the right side of the tuning fork beam inner comb support cantilever (4-1-3) are staggered and inserted to form a second detection comb group; The third detection comb (4-2-7) and the comb on the right side of the fixed single beam outer comb support cantilever (4-2-4) are staggered and inserted to form a third detection comb group; The fourth detection comb teeth (4-2-8) are staggered and inserted with the comb teeth on the left side of the single-beam in-comb teeth support cantilever (4-2-3), forming a fourth detection comb teeth group; The first and second drive comb teeth groups are applied with opposite-phase AC signals, and the third and fourth drive comb teeth groups are applied with opposite-phase AC signals, so as to drive the first double-end fixed tuning fork resonator (4-1) and the first double-end fixed beam resonator (4-2) to vibrate at their inherent frequencies respectively and work in opposite-phase working modes.

4. The asymmetrically coupled stiffness-perturbed MEMS modal localized accelerometer of claim 3, wherein, The tuning fork beam electrostatic coupling parallel plate (4-1-2) and the fixed single-beam electrostatic coupling parallel plate (4-2-2) are parallel and opposite, forming an electrostatic coupling part of the weak coupling resonant system; the electrostatic coupling stiffness is determined by the following formula: ， ， wherein the negative sign indicates a negative stiffness characteristic of the electrostatic coupling; represents the electrostatic coupling stiffness; represents the micro displacement of the acceleration-induced clamped single-beam electrostatically-coupled parallel-plate (4-2-2); is the overlap area of the clamped single-beam electrostatically-coupled parallel-plate (4-2-2) and the tuning fork beam electrostatically-coupled parallel-plate (4-1-2); is the initial gap of the clamped single-beam electrostatically-coupled parallel-plate (4-2-2) and the tuning fork beam electrostatically-coupled parallel-plate (4-1-2); is the difference of the bias voltage applied between the clamped single-beam electrostatically-coupled parallel-plate (4-2-2) and the tuning fork beam electrostatically-coupled parallel-plate (4-1-2); is the dielectric constant; represents the micro displacement and acceleration conversion gain, is the input acceleration; Under small displacement conditions, the relationship between the displacement and the force is linear, and the slope of the line is the stiffness of the system. A first order Taylor expansion is performed at the initial separation d = d0+ δd ， Amplitude ratio of asymmetrically coupled resonators The theoretical expression is: ， wherein, is the equivalent stiffness perturbation introduced by the asymmetric structure; When the acceleration along the positive direction of the X axis When acting on the weakly coupled resonator system, the sensitive mass (2) generates displacement; due to the symmetric distribution of the first asymmetric coupling resonator pair (4) and the second asymmetric coupling resonator pair (5) on both sides of the sensitive mass (2), the displacement will cause the distance between the static coupling plates of the resonator pair on one side to decrease, and the distance between the plates on the other side to increase; The amplitude ratio of the first asymmetric coupling resonator pair (4) and the second asymmetric coupling resonator pair (5) is differentially processed to obtain a final differential detection signal Relationship with acceleration : ， wherein the difference detection signal is the difference between the amplitude ratio of the first asymmetrically coupled resonator pair and the amplitude ratio of the second asymmetrically coupled resonator pair.

5. The asymmetrically coupled stiffness-perturbed MEMS modal localized accelerometer of any one of claims 1-4, wherein, the value of the range is greater than 1 and no more than 3.

6. A detection method for an asymmetrically coupled stiffness-perturbed MEMS modal-localized accelerometer, for processing detection signals of an accelerometer as claimed in any one of claims 1-4, characterized in that, The method comprises the following steps: S1, differentially processing signals output by detection structures on two sides of the first resonator to obtain a first amplitude detection signal ; The second amplitude detection signal is obtained by differentiating the signals output by the detection structure on both sides of the second type of resonator ; S2, the first amplitude detection signal in the same side asymmetric resonator pair is differentiated with the second amplitude detection signal to obtain the amplitude ratio signal of the side = / ; S3, the amplitude ratio signals on both sides of the sensitive mass block are differentiated to output the final differential detection signal ; According to the working principle of the weakly coupled resonant system, the acceleration is obtained from the differential detection signal .

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