CN113552386B - Electrostatic tuning separation type micro-electromechanical accelerometer and closed-loop control method thereof - Google Patents
Electrostatic tuning separation type micro-electromechanical accelerometer and closed-loop control method thereof Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P.I., P.I.D.
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P2015/0862—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with particular means being integrated into a MEMS accelerometer structure for providing particular additional functionalities to those of a spring mass system
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Abstract
The invention discloses an electrostatic tuning separation type micro-electromechanical accelerometer and a closed-loop control method thereof, wherein the accelerometer comprises at least one sensitive mass block, at least one pair of differential resonators, a driving module and a detection module; the resonators are connected with the sensitive mass block in a non-contact mode, and the two sides of each differential resonator are respectively provided with the corresponding driving module and the corresponding detection module which are connected with the differential resonators in a non-contact mode. The accelerometer control scheme comprises two closed-loop circuits, wherein the differential resonator is driven and controlled by the closed loop to realize self-oscillation, and the sensitive mass block is not deflected under the acceleration input by a voltage feedback circuit. The invention avoids the mutual transmission interference of multi-source stress and the circuit noise interference, improves the precision and the stability of the system, and the output and the acceleration of the system work in the control mode to form a linear relation, thereby realizing the requirements of high precision, high stability, small environmental dependence and convenient structural design.
Description
Technical Field
The invention belongs to the technical field of micro inertial sensors in an MEMS (micro-electromechanical system), and particularly relates to an electrostatic tuning separation type micro-electromechanical accelerometer and a closed-loop control method thereof.
Background
Micro-Electro-Mechanical systems (MEMS for short) accelerometers are an important part of Micro inertial sensors, and play a significant role in the fields of aerospace, navigation positioning, attitude control and the like. Nowadays, with the continuous improvement of performance and miniaturization design, MEMS accelerometers are gradually applied in the aspects of life, and therefore, there are higher expectations and requirements for their performance.
The research center of gravity of the MEMS accelerometer has also gradually changed from the capacitive type micro-electromechanical accelerometer to the resonant type micro-electromechanical accelerometer in the last two decades. The capacitive micro-electro-mechanical accelerometer has the advantages that the capacitive micro-electro-mechanical accelerometer is less dependent on the environment due to the displacement change of the capacitor spacing, and the influence of the change of external temperature, stress and the like on devices is less, but the displacement change measured by amplitude detection is easily influenced by the noise of a subsequent circuit, so that the performance is limited; the resonant micro-electromechanical accelerometer changes the equivalent stiffness of a resonator by transmitting the inertia force introduced by the acceleration, and the resonance frequency sensitive acceleration is measured, so that the acceleration signal is directly modulated to the resonance frequency before entering a subsequent circuit, the influence of the subsequent circuit on the resonance frequency is avoided, but the stress transmission mode has high dependence on the external environment and is easily influenced by factors such as residual stress, temperature and the like, and the conventional mainstream resonant accelerometer adopts an integrated design of connecting a sensitive mass block, an inertia force amplification lever and a resonant beam, so that the residual stress between the sensitive mass block and the resonant beam can be mutually transmitted and mutually influenced through the inertia force amplification lever, and the performance stability of the resonant micro-electromechanical accelerometer is limited.
In view of the performance requirements of MEMS micro-electromechanical accelerometers and the common problems in some technical aspects, how to design a novel accelerometer and control method that combines the advantages of capacitive and resonant micro-electromechanical accelerometers has become a problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an electrostatic tuning separation type micro-electromechanical accelerometer and a closed-loop control method thereof, which specifically includes:
an electrostatic tuning separation type micro-electromechanical accelerometer comprises a sensitive mass block, a first differential resonator, a second differential resonator, a driving module and a detection module;
one end of the sensitive mass block is fixed, and gaps are formed between the sensitive mass block and one ends of the first differential resonator and the second differential resonator and voltage is applied to the sensitive mass block and one ends of the first differential resonator and the second differential resonator so as to form capacitance to generate electrostatic connection; the other ends of the first differential resonator and the second differential resonator are respectively fixed;
and the two sides of each differential resonator are respectively provided with a corresponding driving module and a corresponding detection module, and are in non-contact connection with the differential resonators.
The accelerometer control scheme comprises two closed-loop circuits, wherein the differential resonator is driven and controlled by the closed loop to realize self-oscillation, and the sensitive mass block is not deflected under the acceleration input by a voltage feedback circuit.
Compared with the prior art, the invention has the advantages that:
(1) According to the invention, the capacitance displacement signal is directly loaded into the resonator frequency signal before entering a subsequent circuit, compared with the amplitude signal output of the traditional capacitance type micro-electro-mechanical accelerometer, the frequency signal output of the invention is less influenced by the noise of the subsequent circuit, and higher measurement precision and system stability can be obtained.
(2) The design scheme of the invention avoids mutual transmission interference of multi-source stress by adopting the non-contact design of the resonator and the sensitive mass block, compared with the cascade design of the resonator, the amplification lever and the mass block of the traditional resonant micro-electromechanical accelerometer.
(3) The invention adopts a control mode that the frequency square error output and the acceleration form a complete linear relation, the scale factor is obviously improved, and the scale factor depends on the equivalent mass of the sensitive mass block and the resonator, thereby being convenient for design and adjustment.
The invention is described in further detail below with reference to the following drawings and detailed description.
Drawings
FIG. 1 is a simplified schematic diagram of a structural model and a control method according to the present invention.
FIG. 2 is a schematic diagram of structural force analysis according to the present invention.
Detailed Description
An electrostatic tuning separation type micro-electromechanical accelerometer comprises a sensitive mass block 1, a first differential resonator 2, a second differential resonator 3, a driving module 4 and a detection module 5;
one end of the sensitive mass block 1 is fixed, so that the sensitive mass block can displace in the acceleration sensitive direction; a gap is arranged between the sensitive mass block 1 and one end of the first differential resonator 2 and one end of the second differential resonator 3, and voltage is applied to form capacitance to generate electrostatic connection; the other ends of the first differential resonator 2 and the second differential resonator 3 are respectively fixed;
when acceleration is input, the sensing mass 1 can shift in position when being opened, so that the distances between the sensing mass 1 and the first differential resonator 2 and the second differential resonator 3 become larger and smaller, and the first differential resonator 2 and the second differential resonator 3 are subjected to different axial electrostatic forces, so that the first differential resonator 2 and the second differential resonator 3 are at different resonant frequencies.
And two sides of each differential resonator are respectively provided with a corresponding driving module 4 and a corresponding detection module 5, and the driving modules and the detection modules are in non-contact connection with the differential resonators.
Applying a DC bias voltage V to the proof-mass 1 dc And AC high frequency carrier voltage V car A direct current voltage V is input to each of the first differential resonator 2 and the second differential resonator 3 0 And a DC voltage-V 0 。
The detection module 5 is configured to detect and output vibration frequencies of the first differential resonator 2 and the second differential resonator 3, and feed back a detection signal to the driving module 4, so that the frequency of the driving signal is the same as the resonance frequency of the differential resonator, thereby realizing self-oscillation of the first differential resonator 2 and the second differential resonator 3, and enabling the first differential resonator 2 and the second differential resonator 3 to vibrate at the maximum amplitude.
Furthermore, one side of the detection module 5 is connected with the differential resonator in a non-contact manner, the other side of the detection module is connected with the front-end amplification circuit and then is divided into three paths of signals, wherein one path of signal is subjected to amplitude extraction, reference signal Aref comparison and PID, then is synthesized with the other path of signal to form a closed-loop driving feedback signal and is input into the driving module 4, and the third path of signal output by the detection module 5 passes through the frequency reading circuit and then outputs the frequency values of the first differential resonator 2 and the second differential resonator 3, and is resolved into a frequency square difference and is output.
The sensing mass block 1 is provided with a voltage feedback loop and a capacitance voltage C-V conversion circuit, when the sensing mass block 1 is displaced due to acceleration input, the distance between the sensing mass block 1 and any one differential resonator is changed, so that a capacitance value is changed, the voltage feedback loop detects the capacitance value change between the sensing mass block 1 and the differential resonator, the capacitance value change is used as a voltage signal through the capacitance voltage C-V conversion circuit, the voltage signal is converted into a feedback voltage through amplitude extraction and PID control and is applied to the sensing mass block 1, and the sensing mass block 1 is subjected to feedback electrostatic force, returns to an initial position and is stabilized at an initial balance position without displacement.
Further, the sensing mass block 1 is fixed by a connecting beam.
Further, the sensing mass block 1, the first differential resonator 2, the second differential resonator 3, and the driving module 4 and the detecting module 5 corresponding to each differential resonator are a group of acceleration detecting modules, and the electrostatic tuning separation type micro-electromechanical accelerometer includes at least one group of acceleration detecting modules.
A control method of an electrostatic tuning separation type micro-electromechanical accelerometer comprises the following steps:
step 1: when the electrostatic tuning separation type micro-electromechanical accelerometer detects the acceleration towards one side, the sensitive mass block 1 is subjected to the inertia force F towards the other side a Mass to inertia force F in open loop state a Displacement x occurs on the same side, and at the moment, the distance between the sensitive mass block 1 and the first differential resonator 2 and the distance between the sensitive mass block and the second differential resonator 3 change, so that the capacitance value changes;
ΔV 1 ＝V dc -V 0 +v car sinω c t
ΔV 2 ＝V dc +V 0 +v car sinω c t
step 4, the current i in the step 3 flows into a C-V conversion circuit to be converted into a voltage signal, and the voltage signal is converted into a feedback voltage signal V through amplitude extraction and PID control s The potential difference between the first differential resonator 2 and the second differential resonator 3 and the proof mass 1 is:
feedback voltage V s Brings the proof-mass 1 back to the initial position, i.e. x =0, then at this time:
F e1 -F e2 ＝F a
wherein M is the equivalent mass of the sensitive mass block 1, and a is the input acceleration;
since the high-frequency carrier signal has no influence on the transmission of subsequent electrostatic force and the change of the resonator frequency, the high-frequency carrier signal can be omitted for the convenience of derivation, and then the feedback voltage Vs is:
at this time, the electrostatic pull forces on the first differential resonator 2 and the second differential resonator 3 are respectively as follows:
step 6, determining the vibration frequencies of the first differential resonator 2 and the second differential resonator 3 according to the electrostatic tension value obtained in the step 5:
where m is the equivalent mass of a single resonator, k r The equivalent stiffness of a single resonator is obtained, beta is a proportionality coefficient for converting axial force into stiffness, and Vs is substituted to obtain the frequency square error output as follows:
the value of the input acceleration can be obtained, the equation shows that the square difference output of the frequencies of the first differential resonator 2 and the second differential resonator 3 and the acceleration a are in a complete linear relationship, the scale factor is related to the equivalent mass M of the sensitive mass block 1 and the equivalent mass M of the first differential resonator 2 and the second differential resonator 3, and is unrelated to other electrical parameters, and the optimization process is greatly facilitated.
Further, in step 1, when the acceleration direction is right, the sensing mass 1 is subjected to an inertial force F to the left a In the open-loop state, the sensing mass 1 displaces to the left by x, and the distance between the first differential resonator 2 and the sensing mass 1 changes to d 0 + x, the distance between the second differential resonator 3 and the proof mass 1 becomes d 0 X, the point capacitance values formed by the first differential resonator 2, the second differential resonator 3 and the proof mass 1 are:
wherein ε is a dielectric constant, A is a coincidence area of the electrode plates, and d 0 The initial distance of the polar plates;
when the acceleration direction is towards the left, the sensing mass 1 is subjected to a rightward inertial force F a When the proof mass 1 is displaced to the right by x in the open-loop state, the distance between the first differential resonator 2 and the proof mass 1 is d 0 X, the distance between the second differential resonator 3 and the proof mass 1 becomes d 0 + x, at this time, the point capacitance values formed by the first differential resonator 2, the second differential resonator 3 and the proof mass 1 are respectively:
wherein ε is a dielectric constant, A is a coincidence area of the electrode plates, and d 0 Is the initial spacing of the plates.
The present invention will be further described with reference to the following examples.
Examples
With reference to fig. 1, an electrostatic tuning split-type micro-electromechanical accelerometer includes a sensing mass 1, a first differential resonator 2, a second differential resonator 3, a driving module 4, and a detecting module 5;
one end of the sensitive mass block 1 is fixed, so that the sensitive mass block can displace in the acceleration sensitive direction; a gap is arranged between the sensitive mass block 1 and one end of the first differential resonator 2 and one end of the second differential resonator 3, and voltage is applied to form capacitance to generate electrostatic connection; the other ends of the first differential resonator 2 and the second differential resonator 3 are respectively fixed;
when acceleration is input, the sensing mass 1 can shift in position when being opened, so that the distances between the sensing mass 1 and the first differential resonator 2 and the second differential resonator 3 become larger and smaller, and the first differential resonator 2 and the second differential resonator 3 are subjected to different axial electrostatic forces, so that the first differential resonator 2 and the second differential resonator 3 are at different resonant frequencies.
And two sides of each differential resonator are respectively provided with a corresponding driving module 4 and a corresponding detection module 5, and the differential resonators are connected with each other in a non-contact manner.
Applying a DC bias voltage V to the proof mass 1 dc And AC high frequency carrier voltage V car A direct current voltage V is input to each of the first differential resonator 2 and the second differential resonator 3 0 And a DC voltage-V 0 。
The detection module 5 is configured to detect and output vibration frequencies of the first differential resonator 2 and the second differential resonator 3, and feed back a detection signal to the driving module 4, so as to implement self-oscillation of the first differential resonator 2 and the second differential resonator 3.
Furthermore, one side of the detection module 5 is connected with the differential resonator in a non-contact manner, the other side of the detection module is connected with the front-end amplification circuit and then is divided into three paths of signals, wherein one path of signal is subjected to amplitude extraction, reference signal Aref comparison and PID, then is synthesized with the other path of signal to form a closed-loop driving feedback signal and is input into the driving module 4, and the third path of signal output by the detection module 5 passes through the frequency reading circuit and then outputs the frequency values of the first differential resonator 2 and the second differential resonator 3, and is resolved into a frequency square difference and is output.
The sensing mass block 1 is provided with a voltage feedback loop and a capacitance voltage C-V conversion circuit, when the sensing mass block 1 is displaced due to acceleration input, the distance between the sensing mass block 1 and any one differential resonator is changed, so that a capacitance value is changed, the voltage feedback loop detects the capacitance value change between the sensing mass block 1 and the differential resonator, the capacitance value change is used as a voltage signal through the capacitance voltage C-V conversion circuit, the voltage signal is converted into a feedback voltage through amplitude extraction and PID control and is applied to the sensing mass block 1, and the sensing mass block 1 is subjected to feedback electrostatic force, returns to an initial position and is stabilized at an initial balance position without displacement.
Further, the sensing mass 1 is fixed by a connecting beam.
Furthermore, the sensing mass block 1, the first differential resonator 2, the second differential resonator 3, and the driving module 4 and the detecting module 5 corresponding to each differential resonator are a group of acceleration detecting modules, and the electrostatic tuning separation type micro-electromechanical accelerometer includes at least one group of acceleration detecting modules.
With reference to fig. 1 and 2, a method for controlling an electrostatic tuning separation type micro-electromechanical accelerometer includes the following steps:
step 1: when the acceleration direction is right, the sensing mass 1 is subjected to an inertial force F to the left a In the open-loop state, the sensing mass 1 displaces to the left by x, and the distance between the first differential resonator 2 and the sensing mass 1 changes to d 0 + x, the distance between the second differential resonator 3 and the proof mass 1 becomes d 0 X, the point capacitance values formed by the first differential resonator 2, the second differential resonator 3 and the proof mass 1 are:
wherein ε is a dielectric constant, A is a coincidence area of the electrode plates, and d 0 The initial distance of the polar plates;
ΔV 1 ＝V dc -V 0 +v car sinω c t
ΔV 2 ＝V dc +V 0 +v car sinω c t
and 3, continuously flowing out the current containing the capacitance signal by the capacitor formed by the first differential resonator 2 and the sensitive mass block 1, wherein the current value is as follows:
step 4, the current i in the step 3 flows into a C-V conversion circuit to be converted into a voltage signal, and the voltage signal is converted into a feedback voltage signal V through amplitude extraction and PID control s The potential difference between the first differential resonator 2 and the second differential resonator 3 and the proof mass 1 is:
feedback voltage V s Brings the proof-mass 1 back to the initial position, i.e. x =0, then at this time:
F e1 -F e2 ＝F a
wherein M is the equivalent mass of the sensitive mass block 1, and a is the input acceleration;
since the high-frequency carrier signal has no influence on the transmission of the subsequent electrostatic force and the change of the resonator frequency, the high-frequency carrier signal can be omitted for the convenience of derivation, and then the feedback voltage Vs is:
at this time, the electrostatic pull forces on the first differential resonator 2 and the second differential resonator 3 are respectively:
step 6, determining the vibration frequencies of the first differential resonator 2 and the second differential resonator 3 according to the electrostatic tension value obtained in the step 5:
where m is the equivalent mass of a single resonator, k r The equivalent stiffness of a single resonator is obtained, beta is a proportionality coefficient for converting axial force into stiffness, and Vs is substituted to obtain the frequency square error output as follows:
the value of the input acceleration can be obtained, the equation shows that the square error output of the frequencies of the first differential resonator 2 and the second differential resonator 3 and the acceleration a present a complete linear relation, the scale factor is related to the equivalent mass M of the sensitive mass block 1 and the equivalent mass M of the first differential resonator 2 and the second differential resonator 3, and is unrelated to other electrical parameters, and the optimization process is greatly facilitated.
In summary, the electrostatic tuning separation type micro-electromechanical accelerometer and the closed-loop control method thereof provided by the invention can meet the requirements of high precision, high stability, small environmental dependence and convenient structural design.
Finally, although the present specification describes embodiments, not every embodiment includes only a single embodiment, and such descriptions are provided for clarity only, and it is contemplated that the embodiments described herein will be combined as appropriate to form other embodiments as will be apparent to those skilled in the art from consideration of the specification as a whole.
Claims (7)
1. An electrostatic tuning separation type micro-electromechanical accelerometer is characterized by comprising a sensitive mass block (1), a first differential resonator (2), a second differential resonator (3), a driving module (4) and a detection module (5);
one end of the sensitive mass block (1) is fixed, and a gap is arranged between the sensitive mass block (1) and one end of the first differential resonator (2) and one end of the second differential resonator (3) and a voltage is applied to form capacitance to generate electrostatic connection; the other ends of the first differential resonator (2) and the second differential resonator (3) are respectively fixed;
two sides of each differential resonator are respectively provided with a corresponding driving module (4) and a corresponding detection module (5) and are in non-contact connection with the differential resonators;
the control method based on the electrostatic tuning separation type micro-electromechanical accelerometer comprises the following steps:
step 1: electrostatic tuning separate micro-electromechanical accelerationWhen the meter detects the acceleration towards one side, the sensitive mass block (1) is subjected to inertia force F towards the other side a Mass to inertia force F in open loop state a The displacement x occurs on the same side, and at the moment, the distance between the sensitive mass block (1) and the first differential resonator (2) and the distance between the sensitive mass block and the second differential resonator (3) change, so that the capacitance value changes, specifically:
when the acceleration direction is right, the sensitive mass block (1) is subjected to an inertia force F towards the left a In the open-loop state, the sensitive mass block (1) displaces to the left by x, and the distance between the first differential resonator (2) and the sensitive mass block (1) is changed into d 0 + x, the distance between the second differential resonator (3) and the sensing mass (1) becomes d 0 -x, the point capacitance values formed by the first differential resonator (2), the second differential resonator (3) and the proof mass (1) are respectively:
wherein ε is a dielectric constant, A is a coincidence area of the electrode plates, and d 0 The initial distance of the polar plates;
when the acceleration direction is towards the left, the sensitive mass block (1) is subjected to a rightward inertia force F a When the sensing mass (1) is displaced to the right by x in the open-loop state, the distance between the first differential resonator (2) and the sensing mass (1) is changed into d 0 -x, the distance between the second differential resonator (3) and the proof-mass (1) being d 0 + x, at this time, the point capacitance values formed by the first differential resonator (2), the second differential resonator (3) and the proof mass (1) are respectively:
wherein ε is a dielectric constant, A is a coincidence area of the electrode plates, and d 0 Is the initial spacing of the plates
Step 2, applying a direct current voltage V to the first differential resonator (2) 0 The second differential resonator (3) applies a DC voltage-V 0 For DC bias voltage of the sensing mass (1)V dc And AC high frequency carrier voltage V car ，V car ＝v car sinω c t, the potential differences between the first differential resonator (2) and the second differential resonator (3) and the sensing mass block (1) at the moment are respectively as follows:
ΔV 1 ＝V dc -V 0 +v car sinω c t
ΔV 2 ＝V dc +V 0 +v car sinω c t
step 3, a capacitor formed by the first differential resonator (2) and the sensitive mass block (1) continuously flows out current containing a capacitance signal, and the current value is as follows:
step 4, the current i in the step 3 flows into a C-V conversion circuit to be converted into a voltage signal, and the voltage signal is converted into a feedback voltage signal V through amplitude extraction and PID control s Is applied to the sensing mass (1) to enable the sensing mass (1) to return to an initial position, and the potential difference between the first differential resonator (2) and the second differential resonator (3) and the sensing mass (1) is as follows:
feedback voltage V s Brings the proof-mass (1) back to the initial position, i.e. x =0, then at this time:
F e1 -F e2 ＝F a
wherein M is the equivalent mass of the sensitive mass block (1), and a is the input acceleration;
the feedback voltage Vs is:
step 5, applying a direct current bias V dc Set to 0, so that the sensing mass (1) is balanced in the initial 0 position, then:
at this time, the electrostatic pull forces on the first differential resonator (2) and the second differential resonator (3) are respectively as follows:
and 6, determining the vibration frequencies of the first differential resonator (2) and the second differential resonator (3) according to the electrostatic tension value obtained in the step 5:
where m is the equivalent mass of a single resonator, k r The equivalent stiffness of a single resonator is obtained, beta is a proportionality coefficient for converting axial force into stiffness, and Vs is substituted to obtain the frequency square error output as follows:
the value of the input acceleration can be obtained.
2. Electrostatically tuned split microelectromechanical accelerometer according to claim 1, characterized in that a dc bias voltage V is applied to the proof mass (1) dc And AC high frequency carrier voltage V car A DC voltage V is inputted to the first differential resonator 2 and the second differential resonator 3, respectively 0 And a DC voltage-V 0 。
3. The electrostatically tuned split microelectromechanical accelerometer of claim 1, characterized in that the detection module (5) is configured to detect and output the vibration frequency of the first differential resonator (2) and the second differential resonator (3), and to feed back the detection signal to the driving module (4), so as to realize the self-oscillating excitation of the first differential resonator (2) and the second differential resonator (3).
4. The electrostatic tuning separate micro-electromechanical accelerometer according to claim 3, wherein one side of the detection module (5) is connected to the differential resonator in a non-contact manner, the other side of the detection module is connected to the front-end amplification circuit and then divided into three signals, one signal is subjected to amplitude extraction, reference signal Aref comparison and PID, then is combined with the other signal to form a closed-loop driving feedback signal, and is input to the driving module (4), and a third signal output by the detection module (5) passes through the frequency reading circuit and then outputs frequency values of the first differential resonator (2) and the second differential resonator (3).
5. The electrostatic tuning separate type micro-electromechanical accelerometer according to claim 1, wherein a voltage feedback loop and a capacitance-to-voltage (C-V) conversion circuit are disposed on the proof mass (1), when the proof mass (1) is displaced due to an acceleration input, a distance between the proof mass (1) and any one of the differential resonators is changed, so that a capacitance value is changed, the voltage feedback loop detects a change in the capacitance value between the proof mass (1) and the differential resonator, converts the capacitance value into a voltage signal through the capacitance-to-voltage (C-V) conversion circuit, and converts the voltage signal into a feedback voltage through amplitude extraction and PID control, and applies the feedback voltage to the proof mass (1), so that the proof mass (1) receives a feedback electrostatic force, and returns the proof mass (1) to an initial position and stabilizes the proof mass at an initial equilibrium position without displacement.
6. Electrostatically tuned split microelectromechanical-accelerometer according to claim 1, characterized in that the proof-mass (1) is fixed by means of connection beams.
7. The electrostatically tuned split microelectromechanical accelerometer according to claim 1, characterized in that the proof mass (1), the first differential resonator (2), the second differential resonator (3) and the driving module (4) and the detection module (5) respectively corresponding to each differential resonator are a set of acceleration detection modules, and the electrostatically tuned split microelectromechanical accelerometer comprises at least one set of acceleration detection modules.
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