Closed-loop digital output quartz flexible accelerometer

Abstract

The invention discloses a closed-loop digital output quartz flexible accelerometer, and belongs to the technical field of inertial devices. The system comprises a meter head and a closed-loop digital servo circuit. The closed-loop servo circuit comprises a capacitance detection module, an analog-to-digital conversion module, a processor, a digital-to-analog conversion module, a data transmission module and a power supply module. The meter head is used for sensing acceleration information and is connected to the input end of a capacitance detection module in the closed-loop digital servo circuit for conversion to obtain differential voltage, the output end of the capacitance detection module is connected with an analog-to-digital conversion module for obtaining digital information, the SPI bus communication end of the analog-to-digital conversion module is connected with a processor, and the processor is used for processing the acceleration digital information; one part of the communication end of the SPI bus of the processor is connected with the digital-to-analog conversion module, the digital-to-analog conversion module generates an analog current signal, and the current flows to a torquer coil of the meter head and generates Ampere force to realize the balance with acceleration inertia force; and the other part of the serial port communication end of the processor is connected with the data transmission module and outputs digital information describing the acceleration signal to the outside.

Description

Technical Field

[0001] The invention relates to a quartz flexible accelerometer with digital closed-loop output, belonging to the technical field of inertial devices. Background Art

[0002] The quartz flexible accelerometer is a sensor used to measure the accelerometer information of the navigation body. Three orthogonally mounted accelerometers and gyroscopes together constitute the core sensor part of the inertial navigation system.

[0003] The quartz flexible accelerometer is a closed-loop control sensor based on force balance. The basic principle is as follows: acceleration acts on the mass block, causing the mass block to move up and down, causing the capacitance between the surface electrode of the mass block and the upper and lower plates to change; the servo circuit converts the changing capacitance into a current signal, which flows through the torquer in the magnetic field to generate an Ampere force, driving the mass block to move and return to the equilibrium position. The current signal value output by the quartz flexible accelerometer represents its sensitive acceleration. Currently, the most widely used quartz flexible accelerometers all output analog current signals, and the back end of the sensor collects and calibrates the current signal through an analog-to-digital conversion circuit.

[0004] With the development of miniaturization and high integration of inertial navigation systems, quartz flexible accelerometers with analog current signal output cannot meet the development needs of inertial navigation systems because they must be equipped with signal acquisition circuits. Quartz accelerometers with direct digital output have broad application scenarios. Summary of the invention

[0005] In order to solve the problem that the analog output accelerometer in the current inertial navigation system must be equipped with a signal acquisition circuit, which leads to a large volume of the inertial navigation system, the purpose of the present invention is to provide a quartz flexible accelerometer with a digital closed-loop output, which directly outputs a digital signal representing acceleration through a digital servo circuit, improves the anti-interference ability of the sensor signal, and compensates the acceleration signal for scale coefficient and zero bias, thereby improving the modularity of the inertial navigation system.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The invention discloses a closed-loop digital output quartz flexible accelerometer, which comprises a meter head and a closed-loop digital servo circuit.

[0008] The meter head comprises a metal shell, an upper yoke, a lower yoke, an upper torquer magnet, a lower torquer magnet, an upper electrode sheet, a lower electrode sheet, a pendulum sheet assembly and a torquer coil.

[0009] The metal shell is a hollow cylindrical structure, the lower yoke is a hollow structure, installed at the bottom of the shell, the lower torquer magnet is installed at the upper position inside the lower yoke, and the lower electrode sheet is installed at the upper position of the lower torquer magnet; the torquer coil is connected to the center of the swing piece assembly, the swing piece assembly is installed at the upper position outside the lower yoke, the torquer coil is a device in the form of a metal wire winding, the winding axis is a hollow cylinder, the lower electrode sheet and the lower torquer magnet are embedded in the hollow position below the torquer coil, and a certain gap is maintained with the coil; the upper yoke is installed at the upper position of the swing piece assembly, and the upper yoke, upper torquer magnet, upper electrode sheet and lower torquer magnet, lower yoke, and lower electrode sheet are installed symmetrically with the swing piece assembly as the axis. Three signal lines are led out from the swing piece plane, the lower electrode sheet, and the upper electrode sheet, respectively, and are recorded as B1, B2, and B3; two signal lines are led out from the current input end and the current output end of the torquer coil, B4 and B5.

[0010] The digital closed-loop servo circuit structure includes a meter signal interface, an external signal interface, a capacitance detection module, an analog-to-digital conversion module, a processor, a digital-to-analog conversion module, a data transmission module, and a power supply module.

[0011] The meter signal interface has 5 signal interfaces, which are connected to the 5 signal lines B1, B2, B3, B4, and B5 drawn from the meter. B1 and B2 are connected to the capacitance detection module, B3 and B4 are connected to the power module, and B5 is connected to the digital-to-analog conversion module.

[0012] There are 8 external signal interfaces, which are marked as O1, O2, O3, O4, O5, O6, O7, and O8; among them: O1, O2, O3, and O4 are RS-422 interface transmission signals, respectively representing R+ (read positive), R- (read negative), T+ (write positive), and T- (write negative); O5 is the signal test terminal, which is connected to the capacitance detection module; O6, O7, and O8 are the positive power input, negative power input, and ground, respectively, and are connected to the power module.

[0013] The capacitance detection module realizes capacitance detection by applying a triangular wave signal to both ends of the differential capacitor and outputting pulse currents of different amplitudes according to the capacitance integral characteristics. The module has a total of 8 signal interfaces, which are recorded as D1, D2, D3, D4, D5, D6, D7, and D8. Among them: D1 and D2 are capacitance signal interfaces, which are respectively connected to the B1 and B2 signals of the meter signal interface; D3 is the signal test terminal, which is connected to the O5 signal of the external signal interface; D4, D5, and D6 are divided into positive power supply signal, negative power supply signal, and ground signal interfaces, which are connected to the power supply module; D7 and D8 are differential power supply output signals, which are connected to the analog-to-digital conversion module.

[0014] The analog-to-digital conversion module has 11 signal interfaces, which are marked as M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, and M11. Among them: M1 and M2 are differential voltage input signals, which are connected to D7 and D8 of the capacitance detection module; M3, M4, and M5 are positive power supply signals, negative power supply signals, and low signals, which are connected to the power supply module; M6, M7, M8, M9, M10, and M11 are CS1 (chip select signal 1), CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the processor.

[0015] The processor has 11 signal interfaces, which are marked as C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, and C11. Among them: C1 and C2 are power supply signals and ground signals, which are connected to the power supply module; C3 and C4 are CS1 (chip select signal 1) and CS2 (chip select signal 2) of the SPI bus, C3 is connected to the M6 ​​signal of the analog-to-digital conversion module, and C4 is connected to the digital-to-analog conversion module; C5, C6, C7, C8, and C9 are CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the analog-to-digital conversion module and the digital-to-analog conversion module. The analog-to-digital conversion module and the digital-to-analog conversion module share a set of SPI bus signals; C10 and C11 are output digital signals, which are connected to the data transmission module.

[0016] The digital-to-analog conversion module has a total of 10 signal interfaces, denoted as S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10. Among them, S1, S2, and S3 are positive power signals, negative power signals, and ground signals, which are connected to the power module; S4, S5, S6, S7, S8, and S9 are CS2 (chip select signal 2), CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the processor; S10 is a current output signal, which is connected to B5 of the meter signal interface.

[0017] The data transmission module has a total of 8 signal interfaces, denoted as R1, R2, R3, R4, R5, R6, R7, and R8. Among them: R1 and R2 are power signals and ground signals, connected to the power module; R3 and R4 are input signals, connected to C10 and C11 of the processor; R5, R6, R7, and R8 are output digital signals, connected to O1, O2, O3, and O4 of the external signal interface.

[0018] The power module has a total of 9 signal interfaces, denoted as V1, V2, V3, V4, V5, V6, and V7. Among them, V1, V2, and V3 are power input interfaces, connected to O6, O7, and O8 of the external signal interface, V4 and V5 are the positive and negative power signals of the capacitance detection module, connected to D4 and D5; V6 and V7 are the positive and negative power signals of the analog-to-digital conversion module, connected to M3 and M4; V8 is the power signal of the processor, connected to C1; V9 and V10 are the positive and negative power signals of the digital-to-analog conversion module, connected to S1 and S2; V11 is the power signal of the data transmission module, connected to R1; V12 is the ground signal, connected to the ground signals of other modules.

[0019] Digital signals are transmitted via the RS-422 bus, which gives them the advantages of long transmission distance and strong anti-interference signal.

[0020] The present invention discloses a working method of a closed-loop digital output quartz flexible accelerometer, comprising the following steps:

[0021] Step 1: The inertial force generated by the sensor's sensitive acceleration signal drives the pendulum assembly to move △d, thereby changing the distance between the pendulum assembly and the upper electrode sheet and the lower electrode sheet, so that a differential capacitance signal △C is generated between the plates and transmitted to the digital closed-loop servo circuit through the meter signal interface.

[0022] Step 2: The capacitance detection module in the digital closed-loop servo circuit detects and converts the capacitance signal △C to obtain a differential voltage signal △U; the analog-to-digital conversion module samples △U, and the processor reads it through the SPI bus and performs mathematical calculations, and converts it into a digital signal in RS-422 format through the data transmission module;

[0023] Step three, the processor in the digital closed-loop servo circuit controls the digital-to-analog conversion module through the SPI bus to generate a current signal I related to △U, and transmits it to the torquer coil of the meter through the meter signal interface. The torquer coil generates an Ampere force under the joint action of the upper torquer magnet and the lower torquer magnet, and acts on the pendulum assembly to the equilibrium position.

[0024] In step 3, the processor performs the following steps in a complete acquisition, calculation, and transmission cycle:

[0025] Step 1) reading the digital information obtained by converting the differential voltage signal △U in the analog-to-digital conversion module through the SPI bus, and resolving the digital information describing the voltage value of △U into the digital information A0 describing the acceleration;

[0026] Step 2) digitally filtering the acceleration information A0 to obtain filtered acceleration information A1;

[0027] Step 3) compensating the zero bias of the acceleration signal to obtain the acceleration signal A2;

[0028] Step 4) compensating the scale factor of the acceleration signal to obtain the acceleration signal A3;

[0029] Step 5) performing a write operation on the digital-to-analog conversion module via the SPI bus so that it generates a current signal I;

[0030] Step 6) Data is packaged and the acceleration signal A3 is transmitted to the data transmission module via the UART signal, which converts the signal into a digital signal in the form of RS-422.

[0031] In step 1, step 2, and step 3, an external power supply supplies power to a quartz flexible accelerometer with a closed-loop digital output through an external signal interface; an external device reads digital information in the form of RS-422 describing acceleration information through the external signal interface.

[0032] Beneficial effects:

[0033] 1. The invention discloses a closed-loop digital output quartz flexible accelerometer, which adopts the force balance principle, senses acceleration signals through the pendulum assembly, processes the signals through the meter head and the digital closed-loop servo circuit, and outputs digital information in the form of RS-422 indicating the magnitude of acceleration. The invention can realize the digital conversion of acceleration signals, and the back end does not need to add a conversion circuit, and can be directly connected to the navigation computer.

[0034] 2. The present invention discloses a quartz flexible accelerometer with a closed-loop digital output. The digital closed-loop servo circuit adopts capacitor-voltage conversion, analog-to-digital conversion, digital-to-analog conversion and other processes to realize digital closed-loop control of the quartz accelerometer. The current applied to the torquer coil of the meter head and the digital signal output to the outside are both given by the processor. Compared with the method of reading the quartz flexible acceleration current signal by the back-end external conversion circuit, the error is smaller and the measurement value of the acceleration signal is more accurate.

[0035] 3. The present invention discloses a closed-loop digital output quartz flexible accelerometer. The digital closed-loop servo circuit compensates the directly collected signal through a processor, corrects the zero bias and scale coefficient errors of the accelerometer, and improves the integration of the quartz flexible accelerometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is an internal structure diagram of a closed-loop digital output quartz flexible accelerometer disclosed in the present invention;

[0037] Figure 2 It is a structural diagram of a digital closed-loop servo circuit of a quartz flexible accelerometer with closed-loop digital output disclosed by the present invention;

[0038] Figure 3 It is a working principle diagram of a closed-loop digital output quartz flexible accelerometer disclosed in the present invention;

[0039] Figure 4 The invention discloses a program flow chart of a processor in one cycle in a digital closed-loop servo circuit of a quartz flexible accelerometer with closed-loop digital output.

[0040] Among them: 1-meter head, 2-metal shell, 3-upper yoke, 4-lower yoke, 5-upper torquer magnet, 6-lower torquer magnet, 7-upper electrode sheet, 8-lower electrode sheet, 9-swing piece assembly, 10-torquer coil, 11-digital closed-loop servo circuit, 12-meter head signal interface, 13-external signal interface, 14-capacitance detection module, 15-analog-to-digital conversion module, 16-processor, 17-digital-to-analog conversion module, 18-data transmission module, 19-power supply module. DETAILED DESCRIPTION

[0041] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0042] Embodiment 1:

[0043] like Figure 1 , Figure 2 , Figure 3 As shown, the embodiment discloses a closed-loop digital output quartz flexible accelerometer, which is composed of a meter head 1 and a digital closed-loop servo circuit 11 .

[0044] The main structure of the meter head 1 includes a metal shell 2, an upper yoke 3, a lower yoke 4, an upper torquer magnet 5, a lower torquer magnet 6, an upper electrode sheet 7, a lower electrode sheet 8, a pendulum assembly 9, and a torquer coil 10. The metal shell 2 is a hollow cylindrical structure, the lower yoke 4 is a hollow structure, and is installed on the bottom surface of the shell. The lower torquer magnet 6 is installed on the upper position inside the lower yoke 4, and the lower electrode sheet 8 is installed on the upper position of the lower torquer magnet 6; the torquer coil 10 is connected to the center position of the pendulum assembly 9, and the pendulum assembly is installed on the upper position outside the lower yoke 4. The torquer coil 10 is a device in the form of a metal wire winding, and the winding axis is a hollow cylinder. The lower electrode sheet 8 and the lower torquer magnet 6 are embedded in the hollow position below the torquer coil 10, maintaining a certain gap with the coil; the upper yoke 3 is installed on the upper position of the pendulum assembly 9, and the upper yoke 3, the upper torquer magnet 5, the upper electrode sheet 7 and the lower torquer magnet 6, the lower yoke 4, and the lower electrode sheet 8 are installed symmetrically with the pendulum assembly 9 as the axis. Three signal lines are led out from the pendulum plane, the lower electrode sheet 8 and the upper electrode sheet 7, respectively, which are denoted as B1, B2 and B3; two signal lines are led out from the current input end and the current output end of the torquer coil 10, which are denoted as B4 and B5.

[0045] The structure of the digital closed-loop servo circuit 11 includes a meter signal interface 12, an external signal interface 13, a capacitance detection module 14, an analog-to-digital conversion module 15, a processor 16, a digital-to-analog conversion module 17, a data transmission module 18, and a power supply module 19.

[0046] The meter signal interface 12 in the digital closed-loop servo circuit 11 has a total of 5 signal interfaces, which are respectively connected to the five signal lines B1, B2, B3, B4, and B5 drawn from the meter 1. B1 and B2 are connected to the capacitance detection module 14, B3 and B4 are connected to the power module 19, and B5 is connected to the digital-to-analog conversion module 17.

[0047] The external signal interface 13 in the digital closed-loop servo circuit 11 has a total of 8 signal interfaces, which are denoted by O1, O2, O3, O4, O5, O6, O7, and O8; among them: O1, O2, O3, and O4 are RS-422 interface transmission signals, respectively representing R+ (read positive), R- (read negative), T+ (write positive), and T- (write negative); O5 is a signal test terminal, which is connected to the capacitance detection module 14; O6, O7, and O8 are positive power input, negative power input, and ground, respectively, and are connected to the power module 19.

[0048] The capacitance detection module 14 in the digital closed-loop servo circuit 11 has a total of 8 signal interfaces, which are denoted as D1, D2, D3, D4, D5, D6, D7, and D8. Among them: D1 and D2 are capacitance signal interfaces, which are respectively connected to the B1 and B2 signals of the meter signal interface 12; D3 is a signal test terminal, which is connected to the O5 signal of the external signal interface 13; D4, D5, and D6 are divided into positive power signal, negative power signal, and ground signal interfaces, which are connected to the power module 19; D7 and D8 are differential power output signals, which are connected to the analog-to-digital conversion module 15.

[0049] The analog-to-digital conversion module 15 in the digital closed-loop servo circuit 11 has a total of 11 signal interfaces, which are denoted as M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, and M11. Among them: M1 and M2 are differential voltage input signals, which are connected to D7 and D8 of the capacitance detection module 14; M3, M4, and M5 are positive power supply signals, negative power supply signals, and low signals, which are connected to the power supply module 19; M6, M7, M8, M9, M10, and M11 are CS1 (chip select signal 1), CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the processor 16.

[0050] The processor 16 in the digital closed-loop servo circuit 11 has a total of 11 signal interfaces, which are denoted as C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, and C11. Among them: C1 and C2 are power supply signals and ground signals, which are connected to the power supply module 19; C3 and C4 are CS1 (chip select signal 1) and CS2 (chip select signal 2) of the SPI bus, C3 is connected to the M6 ​​signal of the analog-to-digital conversion module 15, and C4 is connected to the digital-to-analog conversion module 17; C5, C6, C7, C8, and C9 are CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the analog-to-digital conversion module 15 and the digital-to-analog conversion module 17, and these two modules share a set of SPI bus signals; C10 and C11 are output digital signals, which are connected to the data transmission module 18.

[0051] The digital-to-analog conversion module 17 in the digital closed-loop servo circuit 11 has a total of 10 signal interfaces, which are denoted as S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10. Among them, S1, S2, and S3 are positive power supply signals, negative power supply signals, and ground signals, which are connected to the power supply module 19; S4, S5, S6, S7, S8, and S9 are CS2 (chip select signal 2), CLK (clock signal), DOUT (output signal), DIN (input signal), RST (reset signal), and DR (conversion completion signal) of the SPI bus, which are connected to the processor 16; S10 is a current output signal, which is connected to B5 of the header signal interface 12.

[0052] The data transmission module 18 in the digital closed-loop servo circuit 11 has a total of 8 signal interfaces, which are denoted as R1, R2, R3, R4, R5, R6, R7, and R8. Among them: R1 and R2 are power supply signals and ground signals, which are connected to the power supply module 19; R3 and R4 are input signals, which are connected to C10 and C11 of the processor 16; R5, R6, R7, and R8 are output digital signals, which are connected to O1, O2, O3, and O4 of the external signal interface 13.

[0053] The power module 19 in the digital closed-loop servo circuit 11 has a total of 9 signal interfaces, which are denoted as V1, V2, V3, V4, V5, V6, and V7. Among them, V1, V2, and V3 are power input interfaces, connected to O6, O7, and O8 of the external signal interface 13, V4 and V5 are the positive power supply and negative power supply signals of the capacitance detection module 14, connected to D4 and D5; V6 and V7 are the positive power supply and negative power supply signals of the analog-to-digital conversion module 15, connected to M3 and M4; V8 is the power supply signal of the processor 16, connected to C1; V9 and V10 are the positive power supply and negative power supply signals of the digital-to-analog conversion module 17, connected to S1 and S2; V11 is the power supply signal of the data transmission module 18, connected to R1; V12 is the ground signal, connected to the ground signals of other modules.

[0054] The described closed-loop digital output quartz flexible accelerometer has an acceleration digital signal transmitted through an RS-422 bus, so that the digital signal has the advantages of long transmission distance and strong anti-interference signal.

[0055] The working method of a closed-loop digital output quartz flexible accelerometer disclosed in this embodiment is specifically implemented in the following steps:

[0056] Step 1: The inertial force generated by the sensor's sensitive acceleration signal drives the pendulum assembly 9 to move by △d, thereby changing the distance between the pendulum assembly 9 and the upper electrode sheet 7 and the lower electrode sheet 8, so that a differential capacitance signal △C is generated between the electrodes and transmitted to the digital closed-loop servo circuit 11 through the meter signal interface 12.

[0057] Step 2: The capacitance detection module 14 in the digital closed-loop servo circuit 11 detects and converts the capacitance signal △C to obtain a differential voltage signal △U; the analog-to-digital conversion module 15 samples △U, and the processor 16 reads it through the SPI bus and performs mathematical calculations, and converts it into a digital signal in RS-422 format through the data transmission module 18;

[0058] Step three, the processor 16 in the digital closed-loop servo circuit 11 controls the digital-to-analog conversion module 17 through the SPI bus to generate a current signal I related to △U, and transmits it to the torquer coil 10 of the meter head 4 through the meter head signal interface 12. The torquer coil 10 generates an Ampere force under the joint action of the upper torquer magnet 5 and the lower torquer magnet 6, and acts on the pendulum assembly 9 to the equilibrium position.

[0059] In step 3, the processor 16 performs the following steps in a complete acquisition, calculation, and transmission cycle:

[0060] Step 1) reading the digital information obtained by converting the differential voltage signal △U in the analog-to-digital conversion module 15 through the SPI bus, and resolving the digital information describing the magnitude of the △U voltage value into the digital information A0 describing the acceleration;

[0061] Step 2) digitally filtering the acceleration information A0 to obtain filtered acceleration information A1;

[0062] Step 3) compensating the zero bias of the acceleration signal to obtain the acceleration signal A2;

[0063] Step 4) compensating the scale factor of the acceleration signal to obtain the acceleration signal A3;

[0064] Step 5) performing a write operation on the digital-to-analog conversion module 17 via the SPI bus so that it generates a current signal I;

[0065] Step 6) Data is packaged and the acceleration signal A3 is transmitted to the data transmission module 18 via the UART signal, which converts the signal into a digital signal in RS-422 format.

[0066] In step 1, step 2, and step 3, an external power source supplies power to the quartz flexible accelerometer with closed-loop digital output via the external signal interface 13; an external device reads digital information in RS-422 format describing acceleration information via the external signal interface 13.

[0067] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A closed-loop digital output quartz flexible accelerometer, characterized in that: It comprises a meter head (1) and a closed-loop digital servo circuit (11); The meter head (1) comprises a metal housing (2), an upper yoke (3), a lower yoke (4), an upper torquer magnet (5), a lower torquer magnet (6), an upper electrode sheet (7), a lower electrode sheet (8), a pendulum assembly (9), and a torquer coil (10); The metal shell (2) is a hollow cylindrical structure, the lower yoke (4) is a hollow structure and is installed at the bottom surface of the shell, the lower torque device magnet (6) is installed at the upper position inside the lower yoke (4), and the lower electrode sheet (8) is installed at the upper position of the lower torque device magnet (6); the torque device coil (10) is connected to the center position of the swing plate assembly (9), and the swing plate assembly is installed at the upper position outside the lower yoke (4); the torque device coil (10) is a device in the form of a metal wire winding, and the winding shaft is a hollow cylinder. The lower electrode sheet (8) and the lower torque device magnet (6) are embedded in the lower electrode sheet (8). A hollow position below the torquer coil (10) is provided, maintaining a certain gap with the coil; the upper yoke (3) is installed above the swing plate assembly (9); the upper yoke (3), the upper torquer magnet (5), the upper electrode plate (7) and the lower torquer magnet (6), the lower yoke (4), and the lower electrode plate (8) are installed symmetrically with the swing plate assembly (9) as the axis; three signal lines are led out from the swing plate plane, the lower electrode plate (8), and the upper electrode plate (7), respectively, and are denoted as B1, B2, and B3; two signal lines, B4 and B5, are led out from the current input end and the current output end of the torquer coil (10).

2. A closed-loop digital output quartz flexible accelerometer as claimed in claim 1, characterized in that: The structure of the digital closed-loop servo circuit (11) includes a meter signal interface (12), an external signal interface (13), a capacitance detection module (14), an analog-to-digital conversion module (15), a processor (16), a digital-to-analog conversion module (17), a data transmission module (18), and a power supply module (19); The meter head signal interface (12) has a total of 5 signal interfaces, which are respectively connected to the 5 signal lines B1, B2, B3, B4, and B5 drawn from the meter head (1); B1 and B2 are connected to the capacitance detection module (14), B3 and B4 are connected to the power supply module (19), and B5 is connected to the digital-to-analog conversion module (17); The external signal interface (13) has a total of 8 signal interfaces, which are denoted as O1, O2, O3, O4, O5, O6, O7, and O8; wherein: O1, O2, O3, and O4 are RS-422 interface transmission signals, respectively representing R+ (read positive), R- (read negative), T+ (write positive), and T- (write negative); O5 is a signal test terminal, which is connected to a capacitance detection module (14); O6, O7, and O8 are respectively a positive power input, a negative power input, and a ground, which are connected to a power module (19).

3. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The capacitance detection module (14) realizes capacitance detection by applying a triangular wave signal to both ends of a differential capacitor and outputting pulse currents of different amplitudes according to the capacitance integral characteristic. The module has a total of 8 signal interfaces, which are denoted as D1, D2, D3, D4, D5, D6, D7, and D8; wherein: D1 and D2 are capacitance signal interfaces, which are respectively connected to the B1 and B2 signals of the meter signal interface (12); D3 is a signal test terminal, which is connected to the O5 signal of the external signal interface (13); D4, D5, and D6 are respectively connected to the positive power supply signal, the negative power supply signal, and the ground signal interface, which are connected to the power supply module (19); and D7 and D8 are differential power supply output signals, which are connected to the analog-to-digital conversion module (15).

4. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The analog-to-digital conversion module (15) has a total of 11 signal interfaces, which are denoted as M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, and M11; wherein: M1 and M2 are differential voltage input signals, which are connected to D7 and D8 of the capacitance detection module (14); M3, M4, and M5 are positive power supply signals, negative power supply signals, and low signals, which are connected to the power supply module (19); M6, M7, M8, M9, M10, and M11 are chip selection signals 1CS1, clock signals CLK, output signals DOUT, input signals DIN, reset signals RST, and DR conversion completion signals of the SPI bus, which are connected to the processor (16).

5. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The processor (16) has a total of 11 signal interfaces, which are denoted as C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, and C11; wherein: C1 and C2 are power supply signals and ground signals, and are connected to a power supply module (19); C3 and C4 are CS1 (chip select signal 1) and CS2 (chip select signal 2) of an SPI bus, C3 is connected to an M6 signal of an analog-to-digital conversion module (15), and C4 is connected to a digital-to-analog conversion module (17); C5, C6, C7, C8, and C9 are clock signals CLK, output signals DOUT, input signals DIN, reset signals RST, and conversion completion signals DR of the SPI bus, and are connected to an analog-to-digital conversion module (15) and a digital-to-analog conversion module (17); the analog-to-digital conversion module (15) and the digital-to-analog conversion module (17) share a set of SPI bus signals; and C10 and C11 are output digital signals, and are connected to a data transmission module (18).

6. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The digital-to-analog conversion module (17) has a total of 10 signal interfaces, which are denoted as S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10; wherein S1, S2, and S3 are positive power supply signals, negative power supply signals, and ground signals, and are connected to the power supply module (19); S4, S5, S6, S7, S8, and S9 are chip select signals 2CS2, clock signals CLK, output signals DOUT, input signals DIN, reset signals RST, and conversion completion signals DR of the SPI bus, and are connected to the processor (16); and S10 is a current output signal, and is connected to B5 of the meter signal interface (12).

7. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The data transmission module (18) has a total of 8 signal interfaces, denoted as R1, R2, R3, R4, R5, R6, R7, and R8; wherein: R1 and R2 are power supply signals and ground signals, connected to the power supply module (19); R3 and R4 are input signals, connected to C10 and C11 of the processor (16); R5, R6, R7, and R8 are output digital signals, connected to O1, O2, O3, and O4 of the external signal interface (13).

8. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, characterized in that: The power module (19) has a total of 9 signal interfaces, which are denoted as V1, V2, V3, V4, V5, V6, and V7; wherein V1, V2, and V3 are power input interfaces, connected to O6, O7, and O8 of the external signal interface (13); V4 and V5 are positive power and negative power signals of the capacitance detection module (14), connected to D4 and D5; V6 and V7 are positive power and negative power signals of the analog-to-digital conversion module (15), connected to M3 and M4; V8 is the power signal of the processor (16), connected to C1; V9 and V10 are positive power and negative power signals of the digital-to-analog conversion module (17), connected to S1 and S2; V11 is the power signal of the data transmission module (18), connected to R1; V12 is a ground signal, connected to ground signals of other modules; Digital signals are transmitted via the RS-422 bus.

9. A closed-loop digital output quartz flexible accelerometer as claimed in claim 2, 3, 4, 5, 6, 7 or 8, characterized in that: The working method includes the following steps: Step 1: The inertial force generated by the sensor's sensitive acceleration signal drives the pendulum assembly (9) to move by a displacement △d, thereby causing the distance between the pendulum assembly (9) and the upper electrode sheet (7) and the lower electrode sheet (8) to change, so that a differential capacitance signal △C is generated between the electrode plates and transmitted to the digital closed-loop servo circuit (11) through the meter signal interface (12); Step 2: The capacitance detection module (14) in the digital closed-loop servo circuit (11) detects and converts the capacitance signal △C to obtain a differential voltage signal △U; the analog-to-digital conversion module (15) samples △U, and the processor (16) reads it through the SPI bus and performs mathematical calculations, and converts it into a digital signal in RS-422 format through the data transmission module (18); Step 3: The processor (16) in the digital closed-loop servo circuit (11) controls the digital-to-analog conversion module (17) through the SPI bus to generate a current signal I related to △U, and transmits the current signal I to the torquer coil (10) of the meter head (4) through the meter head signal interface (12). The torquer coil (10) generates an Ampere force under the joint action of the upper torquer magnet (5) and the lower torquer magnet (6), and moves the pendulum assembly (9) to a balanced position.

10. A closed-loop digital output quartz flexible accelerometer as claimed in claim 9, characterized in that: In step 3, the processor (16) performs the following steps in a complete collection, calculation, and transmission cycle: Step 1) reading digital information obtained by converting the differential voltage signal △U in the analog-to-digital conversion module (15) through the SPI bus, and resolving the digital information describing the magnitude of the voltage value of △U into digital information A0 describing the acceleration; Step 2) digitally filtering the acceleration information A0 to obtain filtered acceleration information A1; Step 3) compensating the zero bias of the acceleration signal to obtain the acceleration signal A2; Step 4) compensating the scale factor of the acceleration signal to obtain the acceleration signal A3; Step 5) performing a write operation on the digital-to-analog conversion module (17) via the SPI bus so that it generates a current signal I; Step 6) Packing the data and transmitting the acceleration signal A3 to the data transmission module (18) via the UART signal, which converts the signal into a digital signal in RS-422 format; In step 1, step 2 and step 3, an external power source supplies power to a quartz flexible accelerometer with a closed-loop digital output through an external signal interface (13); an external device reads digital information in the form of RS-422 describing acceleration information through the external signal interface (13).

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