A dual-axis adjustable acceleration sensor based on modal localization

Abstract

The invention discloses a dual-axis adjustable acceleration sensor based on modal localization, comprising: a mass block for sensing gravity acceleration, four groups of identical drive detection units arranged around the mass block, the left and right drive detection units of the mass block are used to detect acceleration in the x direction, wherein the up and down drive detection units of the mass block are used to detect acceleration in the y direction; the drive detection unit comprises a first resonator and a second resonator; a first tuning fork beam and a second tuning fork beam are coupled electrostatically, a coupling power supply outputs a coupling voltage loaded on the first fixed end connected to the second tuning fork beam, and the coupling power supply is used to adjust the electrostatic coupling strength between the first tuning fork beam and the second tuning fork beam; the first tuning fork beam adjusts the driving force through a first drive electrode; the second tuning fork beam adjusts the driving force through a second drive electrode; the invention realizes online adjustment of sensor sensitivity, resolution and detection range, and has the advantages of high sensitivity, strong robustness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, and in particular to a dual-axis adjustable acceleration sensor based on modal localization, belonging to the field of sensors. Background Art

[0002] Accelerometers are commonly used in various fields such as medical treatment, transportation, and aerospace. According to different detection mechanisms, accelerometers are generally divided into capacitive, piezoresistive, and resonant types. Among them, resonant accelerometers are widely used due to their quasi-digital signals and high sensitivity. Its detection principle is to detect the offset of the resonator frequency by affecting the change of the axial force of the resonator through the inertial force of the mass block. In order to improve the frequency sensitivity, the sensitivity is usually improved by optimizing the geometry of the resonator and amplifying the inertial force using a lever mechanism. J. Zhang et al. proposed a new type of accelerometer design in "Microelectromechanical Resonant Accelerometer Designed with a High Sensitivity," (Sensors (Basel), vol. 15, no. 12, pp. 30293-310, Dec 3 2015.), which achieved higher sensitivity by optimizing the configuration of the resonator and optimizing the performance of the amplifying lever, but the temperature sensitivity of the resonant accelerometer still exists. H. Zhang et al. proposed a single-axis acceleration sensor based on the mode localization effect in "An Acceleration Sensing Method Based on the Mode Localization of Weakly Coupled Resonators," (Journal of Microelectromechanical Systems, vol. 25, no. 2, pp. 286-296, 2016) which has good sensitivity and good resistance to temperature sensitivity.

[0003] In summary, the resonant acceleration sensor based on the frequency shift output mode is easily affected by the external environment, while the acceleration sensor introducing the modal localization effect has better anti-interference ability. Therefore, the inventors propose a differential dual-axis sensor based on the modal localization effect. Summary of the invention

[0004] In order to solve the technical problems that the resonant accelerometer is difficult to improve due to the frequency shift output sensitivity and has poor robustness to the external environment, the present invention provides a dual-axis adjustable accelerometer based on modal localization. The sensor uses a resonator composed of equal-length fixed beams, and the two fixed beams are coupled by electrostatics, which makes it easy to adjust the coupling strength, thereby achieving the most suitable coupling strength in theory, and does not require any structural optimization. It has the advantages of simple process, stable configuration, and easy processing, and can be widely used in various aspects. The specific technical solution adopted by the present invention is as follows:

[0005] A dual-axis adjustable acceleration sensor based on modal localization, comprising: a mass block for sensing gravity acceleration, four groups of identical drive detection units arranged around the mass block, wherein the left and right drive detection units of the mass block are used to detect acceleration in the x direction, and the up and down drive detection units of the mass block are used to detect acceleration in the y direction;

[0006] Each drive detection unit has the same function;

[0007] The driving detection unit comprises a first resonator and a second resonator; under the action of external acceleration, the mass block (1) is displaced, and the displacement of the mass block (1) causes the amplitude-frequency changes of the corresponding first resonator and the second resonator to complete the detection, and the first resonator and the second resonator are symmetrically arranged;

[0008] The first resonator is formed by a first tuning fork beam;

[0009] The second resonator is formed by a second tuning fork beam;

[0010] The lengths of the first tuning fork beam and the second tuning fork beam are variable and equal;

[0011] The first tuning fork beam is placed above the second tuning fork beam;

[0012] Two ends of the first tuning fork beam are respectively fixed by a first fixed end and a fourth fixed end;

[0013] The two ends of the second tuning fork beam are respectively fixed by the first fixed end and the first micro-lever structure and the first micro-lever structure;

[0014] The first micro-lever structure is connected to the mass block via a first axial decoupling structure;

[0015] The second micro-lever structure is connected to the mass block via the second axial decoupling structure;

[0016] Wherein, the first tuning fork beam and the second tuning fork beam are coupled by electrostatic coupling, a coupling power supply outputs a coupling voltage which is loaded on the first fixed end connected to the second tuning fork beam, and the coupling power supply is used to adjust the electrostatic coupling strength between the first tuning fork beam and the second tuning fork beam;

[0017] The first tuning fork beam adjusts the driving force through the first driving electrode; the second tuning fork beam adjusts the driving force through the second driving electrode;

[0018] The first tuning fork beam and the second tuning fork beam detect amplitude and frequency through the first detection electrode and the second detection electrode respectively.

[0019] Further, the length of the first driving electrode is equal to the length of the second driving electrode, and the width of the first driving electrode is equal to the width of the second driving electrode.

[0020] Further, the length of the first detection electrode is equal to the length of the second detection electrode, and the width of the first detection electrode is equal to the width of the second detection electrode.

[0021] Further, the length of the first driving electrode is equal to the tuning fork length of the first tuning fork beam, and the width of the first driving electrode is equal to the width of the first tuning fork beam; the length of the second driving electrode is equal to the tuning fork length of the second tuning fork beam, and the width of the second driving electrode is equal to the width of the second tuning fork beam.

[0022] Further, the gap between the first driving electrode and the first tuning fork beam is equal to the gap between the second driving electrode and the second tuning fork beam, which is equal to the distance between the second tuning fork beam and the first tuning fork beam.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present invention has the characteristic of easy adjustment of coupling strength, and the coupling strength between the clamped beams can be changed only by voltage adjustment;

[0025] 2. The present invention adopts an axial decoupling device, and realizes the detection of bidirectional acceleration of a single resonator through the mechanical characteristics of the axial decoupling device;

[0026] 3. The present invention utilizes the modal localization phenomenon, which will cause a sharp change in the eigenvalue and amplitude ratio when subjected to a very small disturbance, and has ultra-high sensitivity.

[0027] In summary, the present invention provides a differential acceleration sensor based on the modal localization effect, which realizes online adjustment of the sensitivity and resolution of the sensor by adjusting the coupling voltage to change the electrostatic coupling strength. The first tuning fork beam and the second tuning fork beam are driven by the first fixed excitation electrode and the second fixed excitation electrode respectively. When the acceleration generates the mass block to move, the amplitude of the two resonators is changed by the lever, and the magnitude of the acceleration can be obtained by calculating the amplitude ratio of the two resonators. Compared with the traditional frequency-shift output method, the amplitude ratio output has better ability to resist external environmental interference, better robustness and higher sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 It is a structural schematic diagram of a dual-axis adjustable acceleration sensor based on modal localization in an implementation case of the present invention;

[0030] Figure 2 (a) is an amplitude-frequency characteristic diagram of a transverse tuning fork beam in a balanced state in an embodiment of the present invention; (b) is an amplitude-frequency characteristic diagram of a longitudinal tuning fork beam in a balanced state in an embodiment of the present invention;

[0031] Figure 3 (a) is a curve showing a relative amplitude ratio change of the first transverse clamped beam in an embodiment of the present invention when a 1g acceleration disturbance is applied in the y-axis direction at a coupling voltage of 217V;

[0032] (b) is a curve showing a relative amplitude ratio change of the second transverse clamped beam in an embodiment of the present invention when a 1g acceleration disturbance is applied in the y-axis direction at a coupling voltage of 217V;

[0033] Figure 4 (a) is a curve showing a relative amplitude ratio change of the first longitudinal clamped beam when a 1g acceleration disturbance is applied in the y-axis direction in an embodiment of the present invention;

[0034] (b) is a curve showing a relative amplitude ratio change of the second longitudinal clamped beam when a 1g acceleration disturbance is applied in the y-axis direction in an embodiment of the present invention;

[0035] In the figure: 1, mass block; 2, drive detection unit; 2-1, first fixed end, 2-2, second fixed end; 2-3, first drive electrode; 2-4, second drive electrode; 2-5, first detection electrode; 2-6, second detection electrode; 2-7, first tuning fork beam; 2-8, second tuning fork beam; 2-9, third fixed end; 2-10, fourth fixed end; 2-11, fifth fixed end; 2-12, first micro-lever structure; 2-13, second micro-lever; 2-14, first axial decoupling structure; 2-15, second axial decoupling structure. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] Through my research, I found that by introducing the modal localization phenomenon into the study of accelerometers and adopting a new sensitive mechanism with eigenvalues ​​or amplitude ratios as output metrics, the sensitivity of the sensor can be greatly improved, and a relatively high sensitivity can be obtained without structural optimization or the use of levers. In a nearly symmetrical weakly coupled system that introduces the modal localization effect, when the sensor is disturbed, the system symmetry will be destroyed, resulting in a sharp change in the characteristic state and amplitude ratio. Based on this phenomenon, an accelerometer with extremely high sensitivity is designed.

[0038] like Figure 1 As shown, the present invention provides a structural schematic diagram of a dual-axis adjustable acceleration sensor based on modal localization, including:

[0039] A mass block 1 for sensing gravity acceleration, with four groups of identical driving detection units 2 arranged around the mass block, which will cause the amplitude-frequency change of the detection units when the mass block 1 is displaced under the action of external acceleration, namely, a first detection unit and a second detection unit arranged in the horizontal direction of the mass 1, on the left and right sides of the mass 1; and also including a third detection unit and a fourth detection unit arranged in the vertical direction of the mass 1, on the upper and lower sides of the mass 1;

[0040] The first detection unit, the second detection unit, the third detection unit and the fourth detection unit have the same structure;

[0041] The mass block 1 drives the first detection unit and the second detection unit on the left and right sides to detect the acceleration in the x direction, and the mass block 1 drives the third detection unit and the fourth detection unit on the upper and lower sides to detect the acceleration in the y direction; the first driving unit is taken as an example, and the other units have the same structure as the first driving unit;

[0042] The detection unit 2 includes a first resonator and a second resonator; the first resonator and the second resonator are symmetrically arranged; the first resonator and the second resonator have the same structure; the first resonator and the second resonator are used to detect the amplitude-frequency change caused by the displacement change of the mass block 1 caused by external acceleration;

[0043] The first resonator is composed of a first tuning fork beam 2-7;

[0044] The second resonator is formed by a second tuning fork beam 2-8;

[0045] The lengths of the first tuning fork beam 2-7 and the second tuning fork beam 2-8 are variable and equal;

[0046] The first tuning fork beam 2-7 is placed above the second tuning fork beam 2-8;

[0047] The two ends of the first tuning fork beam 2-7 are respectively fixed by a first fixed end 2-1 and a fourth fixed end 2-10;

[0048] The two ends of the second tuning fork beam 2-8 are respectively fixed by the second fixed end 2-2 and the first micro-lever structure 2-12 and the second micro-lever structure 2-13;

[0049] The first micro-lever structure 2-12 is connected to the mass block 1 through a first axial decoupling structure 2-14;

[0050] The second micro-lever structure 2-13 is connected to the mass block 1 via a second axial decoupling structure 2-15;

[0051] The first tuning fork beam 2-7 and the second tuning fork beam 2-8 are electrostatically coupled, and a coupling power supply outputs a coupling voltage which is loaded on the first fixed end 2-1 connected to the second tuning fork beam 2-8, and the coupling power supply is used to adjust the electrostatic coupling strength between the first tuning fork beam 2-7 and the second tuning fork beam 2-8;

[0052] The first tuning fork beam 2 - 7 adjusts the driving force through the first driving electrode 2 - 3 ; the second tuning fork beam 2 - 8 adjusts the driving force through the second driving electrode 2 - 4 .

[0053] The first tuning fork beam 2-7 detects the amplitude and frequency through the first detection electrode 2-5;

[0054] The second tuning fork beam 2-8 detects the amplitude and frequency through the second detection electrode 2-6;

[0055] The length of the first driving electrode 2 - 3 is equal to the length of the second driving electrode 2 - 4 , and the width of the first driving electrode 2 - 3 is equal to the width of the second driving electrode 2 - 4 .

[0056] The length of the first detection electrode 2 - 6 is equal to the length of the second detection electrode 2 - 7 , and the width of the first detection electrode 2 - 6 is equal to the width of the second detection electrode 2 - 7 .

[0057] The length of the first driving electrode 2-3 is equal to the tuning fork length of the first tuning fork beam 2-7, and the width of the first driving electrode 2-3 is equal to the width of the first tuning fork beam 2-7; the length of the second driving electrode 2-4 is equal to the tuning fork length of the second tuning fork beam 2-8, and the width of the second driving electrode 2-4 is equal to the width of the second tuning fork beam 2-8.

[0058] The gap between the first driving electrode 2-3 and the first tuning fork beam 2-7 is equal to the gap between the second driving electrode 2-4 and the second tuning fork beam 2-8, which is equal to the distance between the second tuning fork beam 2-8 and the first tuning fork beam 2-7.

[0059] The present invention provides a differential acceleration sensor based on the modal localization effect, which realizes online adjustment of the sensitivity and resolution of the sensor by adjusting the coupling voltage to change the electrostatic coupling strength. The first tuning fork beam and the second tuning fork beam are driven by the first fixed excitation electrode and the second fixed excitation electrode respectively. When the mass block moves under the action of external disturbance, the amplitude will change. The magnitude of the inclination angle can be obtained by calculating the amplitude ratio of the two resonators. Compared with the traditional frequency shift output method, the amplitude ratio output has better ability to resist external environmental interference, better robustness and higher sensitivity.

[0060] Example 1

[0061] A differential acceleration sensor based on modal localization effect provided by the present invention is described below with a specific example.

[0062] like Figure 1 The structure diagram of a differential acceleration sensor based on modal localization effect in an embodiment of the present invention is shown. The mass block is connected to the resonator through an amplifying lever. When the mass block is subjected to the external acceleration, the axial stress of the resonator is changed, thereby breaking the resonator in a balanced state and causing energy localization. The magnitude of the external acceleration is calculated by measuring the amplitude ratio of the two resonators.

[0063] Compared with the traditional mechanical coupling structure, the electrostatic coupling adopted in the present invention can adjust the coupling strength in real time and easily achieve low coupling stiffness. Figure 2 It is shown as an amplitude-frequency characteristic diagram of the acceleration sensor of the present invention when it is in a balanced state according to the dimensions in the structural parameter table 1 of the present invention in an embodiment of the present invention, wherein the abscissa is the frequency (kHz) and the ordinate is the amplitude (μm).

[0064] Table 1

[0065]

[0066] Figure 2 (a) is an amplitude-frequency characteristic diagram of a transverse tuning fork beam in a balanced state in an embodiment of the present invention; (b) is an amplitude-frequency characteristic diagram of a longitudinal tuning fork beam in a balanced state in an embodiment of the present invention;

[0067] Figure 2 1 is a curve showing a change in the amplitude-frequency characteristics of the transverse and longitudinal resonators in a balanced state in an embodiment of the present invention.

[0068] Figure 3 (a) is a curve showing a relative amplitude ratio change of the first transverse clamped beam in an embodiment of the present invention when a 1g acceleration disturbance is applied in the y-axis direction at a coupling voltage of 217V;

[0069] (b) is a curve showing a relative amplitude ratio change of the second transverse clamped beam in an embodiment of the present invention when a 1g acceleration disturbance is applied in the y-axis direction at a coupling voltage of 217V;

[0070] Figure 4 (a) is a curve showing a relative amplitude ratio change of the first longitudinal clamped beam when a 1g acceleration disturbance is applied in the y-axis direction in an embodiment of the present invention;

[0071] (b) is a curve showing a relative amplitude ratio change of the second longitudinal clamped beam when a 1g acceleration disturbance is applied in the y-axis direction in an embodiment of the present invention;

[0072] Figure 3 1 is a curve showing a change in the relative amplitude ratio of the two transverse clamped beams when a 1g acceleration disturbance is applied in the y-axis direction in an embodiment of the present invention.

[0073] Figure 4 is a curve showing the relative amplitude ratio variation of the two longitudinal clamped beams in the embodiment of the present invention when a 1g acceleration disturbance is applied in the y-axis direction, and Figure 3 By comparing the results in Figure 2, it can be found that the acceleration sensor has good decoupling ability.

Claims

1. A dual-axis adjustable acceleration sensor based on modal localization, characterized in that: include: A mass block (1) for sensing gravitational acceleration, wherein four groups of identical drive detection units (2) are arranged around the mass block (1), wherein the left and right drive detection units (2) of the mass block (1) are used to detect acceleration in the x direction, and wherein the up and down drive detection units (2) of the mass block (1) are used to detect acceleration in the y direction; Each drive detection unit has the same function; The detection unit comprises a first resonator and a second resonator, and causes displacement of a mass block (1) under the action of external acceleration, and the displacement of the mass block (1) causes amplitude-frequency changes of the corresponding first resonator and the second resonator to complete the detection; The first resonator and the second resonator are symmetrically arranged; The first resonator is composed of a first tuning fork beam (2-7); The second resonator is composed of a second tuning fork beam (2-8); The lengths of the first tuning fork beam (2-7) and the second tuning fork beam (2-8) are variable and equal; The first tuning fork beam (2-7) is placed above the second tuning fork beam (2-8); Two ends of the first tuning fork beam (2-7) are respectively fixed by a first fixed end (2-1) and a fourth fixed end (2-11); Two ends of the second tuning fork beam (2-8) are respectively fixed by a first fixed end (2-2) and a first micro-lever structure (2-12) and a second micro-lever structure (2-13); The first micro-lever structure (2-12) is connected to the mass block (1) via a first axial decoupling structure; The second micro-lever structure (2-13) is connected to the mass block (10) via a second axial decoupling structure (2-15); The first tuning fork beam (2-7) and the second tuning fork beam (2-8) are coupled via electrostatic coupling, a coupling power supply outputs a coupling voltage which is loaded on the first fixed end (2-2) connected to the second tuning fork beam (2-8), and the coupling power supply is used to adjust the electrostatic coupling strength between the first tuning fork beam (2-7) and the second tuning fork beam (2-8); The first tuning fork beam (2-7) adjusts the driving force through the first driving electrode (2-3); the second tuning fork beam (2-8) adjusts the driving force through the second driving electrode (2-4); The first tuning fork beam (2-7) and the second tuning fork beam (2-8) detect amplitude and frequency through a first detection electrode (2-5) and a second detection electrode (2-6) respectively.

2. The dual-axis adjustable acceleration sensor based on modal localization according to claim 1, characterized in that: The length of the first driving electrode (2-3) is equal to the length of the second driving electrode (2-4), and the width of the first driving electrode (2-3) is equal to the width of the second driving electrode (2-4).

3. The dual-axis adjustable acceleration sensor based on modal localization according to claim 1, characterized in that: The length of the first detection electrode (2-5) is equal to the length of the second detection electrode (2-6), and the width of the first detection electrode (2-5) is equal to the width of the second detection electrode (2-6).

4. The dual-axis adjustable acceleration sensor based on modal localization according to claim 1, characterized in that: The length of the first driving electrode (2-3) is equal to the tuning fork length of the first tuning fork beam (2-7), and the width of the first driving electrode (2-3) is equal to the width of the first tuning fork beam (2-7); The length of the second driving electrode (2-4) is equal to the tuning fork length of the second tuning fork beam (2-8), and the width of the second driving electrode (2-4) is equal to the width of the second tuning fork beam (2-8).

5. The dual-axis adjustable acceleration sensor based on modal localization according to claim 1, characterized in that: The gap between the first driving electrode (2-3) and the first tuning fork beam (2-7) is equal to the gap between the second driving electrode (2-4) and the second tuning fork beam (2-8), and equal to the distance between the second tuning fork beam (2-8) and the first tuning fork beam (2-7).

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