Cubic accelerometer measurement and control circuit ground test system and method

Abstract

The invention discloses a cubic accelerometer measurement and control circuit ground test system and method, relates to the technical field of microgravity detection, and can be used for carrying out ground experimental verification on a cubic accelerometer and verifying the correctness of the cubic accelerometer, the effectiveness of a control algorithm and the like. Through mutual cooperation of the flat accelerometer measurement and control circuit, the high-voltage driving module and the cubic accelerometer measurement and control circuit, capture control of a horizontal axis of a flat sensor is realized, and ground verification is performed on a hardware circuit and a software control algorithm of the cubic accelerometer measurement and control circuit. Based on the inherent advantages of the flat accelerometer, the ground closed loop verification of the cubic accelerometer measurement and control circuit can be realized, the method is simple and easy to implement, the in-orbit application risk of the cubic accelerometer can be effectively reduced, the in-orbit working reliability of the cubic accelerometer can be improved, and the method can better adapt to the complex space environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of space microgravity detection, and particularly relates to a cubic accelerometer measurement and control circuit ground test system and method. BACKGROUND

[0002] The electrostatic suspension accelerometer is mainly used for satellite precise orbit determination, and measures the satellite perturbation acceleration caused by solar pressure to provide data support for satellite orbit determination and orbit compensation. Since the electrostatic suspension accelerometer has a small range and a very high measurement resolution, which is much larger than the gravity acceleration of the earth, it is difficult to comprehensively test the function and performance of the electrostatic suspension accelerometer on the ground.

[0003] In the design of space products, in order to effectively improve the on-orbit working reliability of space products, almost all space products need to carry out large-scale and comprehensive ground tests, and the electrostatic suspension accelerometer is no exception. Limited by the working characteristics of the electrostatic suspension accelerometer and the influence of the ground gravity acceleration, special experiments need to be carried out on the hardware circuit function and software control algorithm of the electrostatic suspension accelerometer for test verification.

[0004] At present, the electrostatic suspension accelerometer in China basically adopts a sensor composed of a flat proof mass, and a high voltage of about 1000V is applied to three electrodes in the vertical direction of the sensor to overcome the 1g gravity acceleration of the earth, so as to test the function and performance of the horizontal axis. However, the flat shape of the flat proof mass of the flat accelerometer leads to a higher measurement resolution of the horizontal axis and a lower measurement resolution of the vertical axis, and there is a distinction between the sensitive axis and the non-sensitive axis. The cubic accelerometer adopts a cubic proof mass, and the measurement resolutions of the X, Y and Z directions are basically consistent, that is, the three axes have the same sensitivity.

[0005] The cubic accelerometer cannot be directly tested by high-voltage suspension on the ground due to its special structure. The cubic accelerometer basically consists of a measurement and control circuit and a sensor, and the sensor mainly acts as a capacitive sensitive probe. Under the condition of sufficient lubrication coating and capacitance test, the influence on the on-orbit stable control of the accelerometer is small, but the measurement and control circuit involves many hardware parameters, software algorithms and control parameters. Therefore, sufficient ground test verification can significantly improve the on-orbit control stability of the accelerometer and reduce the risk of on-orbit stable control of the accelerometer.

[0006] Therefore, how to realize the ground verification of the measurement and control circuit of the cubic accelerometer is a problem that has not been solved at present. SUMMARY

[0007] Therefore, the present application provides a cubic accelerometer measurement and control circuit ground test system and method, which can realize closed-loop verification of the measurement and control circuit of the cubic accelerometer.

[0008] To achieve the above objectives, the present invention provides a ground testing system for a cubic accelerometer measurement and control circuit, including a flat accelerometer measurement and control circuit, a cubic accelerometer measurement and control circuit, a high-voltage drive module, a flat sensor, and a three-axis displacement stage.

[0009] The cubic accelerometer control circuit is connected to the flat accelerometer control circuit. The flat accelerometer control circuit provides the cubic accelerometer control circuit with the TTL demodulation signal required for its analog demodulation. The cubic accelerometer control circuit is connected to the horizontal electrode plate of the flat sensor. The cubic accelerometer control circuit controls the horizontal direction of the flat sensor's inspection quality to the center position of the front and rear electrodes and the left and right electrodes.

[0010] The flat accelerometer measurement and control circuit is connected to the high-voltage drive module, which is connected to the upper electrode plate of the flat sensor in the vertical direction. The flat accelerometer suspends the test mass of the flat sensor in the middle position of the upper and lower electrode plates in the vertical direction.

[0011] The flat sensor is placed on a three-axis displacement stage, which is used to adjust the attitude of the flat sensor and adjust the magnitude of its horizontal gravitational acceleration component, so as to realize the capture control of the flat sensor's horizontal axis by the cubic accelerometer measurement and control circuit.

[0012] Furthermore, it also includes a first monitor and a second monitor; the first monitor is used to communicate with the flat accelerometer measurement and control circuit, set the corresponding control parameters, and store data; the second monitor is used to communicate with the cubic accelerometer measurement and control circuit, set the corresponding control parameters, and store data.

[0013] Furthermore, it also includes a first DC power supply, a second DC power supply, and a third DC power supply; the first DC power supply, the second DC power supply, and the third DC power supply provide the required DC voltage for the flat accelerometer measurement and control circuit, the cubic accelerometer measurement and control circuit, and the high-voltage drive module, respectively.

[0014] Furthermore, the three-axis displacement stage consists of a calibration platform and three support columns. The calibration platform is a triangular marble platform, and the three support columns are metal support columns with adjustable height via a spiral mechanism. The top of the support columns has a spherical structure, and the three corners of the marble platform that contact the support columns are designed as semi-circular grooves, referred to as positioning grooves, to provide a constraint that matches the top shape of the support columns and restrict the translation between the calibration platform and the support columns.

[0015] Furthermore, during testing, the flat sensor is placed in the middle of the calibration platform. When high-pressure suspension control begins, the height of the three support columns is adjusted to be the same. After the vertical axis is stabilized by high-pressure suspension, the height of the support columns is adjusted so that the gravitational acceleration component of the horizontal axis of the test mass enters the capture range of the cube accelerometer measurement and control circuit, and servo feedback control is performed on the horizontal axis of the flat sensor.

[0016] Furthermore, the flat accelerometer measurement and control circuit includes a vertical axis capacitive displacement detection circuit, a capacitive displacement acquisition ADC1, and a digital controller 1. The capacitive displacement acquisition ADC1 uses an AD7767 chip with a sampling rate of 100kHz. After calculation by the digital controller 1, the feedback voltage is output to the high-voltage drive module and applied to the electrodes in the vertical axis direction of the flat sensor. The voltage of the high-voltage drive module is 1000V, which is used to overcome the ground gravity and make the test mass suspend at the center of the electrode cage.

[0017] Furthermore, the cubic accelerometer measurement and control circuit includes a horizontal axis capacitive displacement monitoring circuit, a capacitive displacement acquisition ADC2, a filtering circuit, a low-voltage drive module, and a digital controller 2. The capacitive displacement acquisition ADC2 uses an AD7767-2 chip with a sampling rate set to 1.25kHz. After calculation by the digital controller 2, the feedback voltage is output to the low-voltage drive module. After passing through the filtering circuit, it is applied to the front-back and left-right electrodes in the horizontal axis direction of the flat sensor. The voltage of the low-voltage drive module is 14V, which is used to compensate for the horizontal component of gravitational acceleration, so that the test mass can be stably suspended in the center position of the electrode cage in the horizontal axis direction. This realizes the closed-loop verification of the cubic accelerometer measurement and control circuit and the software control algorithm.

[0018] Another aspect of this invention provides a test method for a ground-based test system for a cubic accelerometer measurement and control circuit. Using the aforementioned ground-based test system for the cubic accelerometer measurement and control circuit, the following test steps are performed: Step (1) Turn on the first DC power supply, set the output voltage of the first DC power supply to the working voltage of the flat accelerometer, turn on the first monitor, and open the host computer communication software on the first monitor to establish communication between the first monitor and the flat accelerometer, and set the control parameters of the flat accelerometer through the first monitor. Step (2) Turn on the third DC power supply and set the output voltage of the third DC power supply to the working voltage of the high voltage drive module. Turn on the high voltage drive module and slowly turn on the knob switch of the high voltage drive module. At the same time, observe the capacitor displacement monitoring curve on the first monitor and observe whether the vertical capacitor displacement detection voltage fluctuates within the set range of about 0V. When the vertical capacitor displacement detection voltage suddenly drops to 0V and fluctuates within the set range of about 0V, it indicates that the vertical direction of the flat sensor has been captured and controlled. Step (3) Turn on the second DC power supply and set the output voltage of the second DC power supply to the working voltage of the cubic accelerometer measurement and control circuit. Turn on the second monitor and open the host computer communication software on the second monitor to establish communication between the second monitor and the cubic accelerometer measurement and control circuit. Set the control parameters of the cubic accelerometer measurement and control circuit through the second monitor. At the same time, observe the capacitor displacement monitoring curve on the second monitor and observe whether the capacitor displacement detection voltage in the horizontal direction fluctuates within the set range of about 0V. When the capacitor displacement detection voltage in the horizontal direction fluctuates within the set range of about 0V, it indicates that the capture control of the horizontal axis of the flat sensor has been realized.

[0019] Beneficial effects: This invention achieves capture and control of the horizontal axis of a flat accelerometer sensor through the coordinated operation of a flat accelerometer control circuit, a high-voltage drive module, and a cubic accelerometer control circuit. Ground-based verification of the cubic accelerometer control circuit was also conducted. The test system is simple, the test method is clear and easy to implement, and it can effectively test the correctness of the cubic accelerometer control circuit and software control algorithm design, significantly improving the on-orbit reliability of the cubic accelerometer. Attached Figure Description

[0020] Figure 1 This is a block diagram of a ground testing system for a cubic accelerometer measurement and control circuit provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the three-axis displacement stage structure in an embodiment of the present invention; Figure 3 This diagram illustrates the differences between the flat accelerometer control circuit and the cubic accelerometer control circuit in this invention. Figure 4 This is a flowchart of the ground testing method for the cubic accelerometer measurement and control circuit of the present invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] Example 1: The implementation of the ground testing system for the cubic accelerometer measurement and control circuit provided in this embodiment of the invention is as follows: Figure 1As shown, it includes a first monitor, a second monitor, a flat accelerometer control circuit, a cubic accelerometer control circuit, a high-voltage drive module, a first DC power supply, a second DC power supply, a third DC power supply, a three-axis displacement stage, and flat sensors and corresponding connecting cables.

[0023] The first monitor is connected to the flat accelerometer control circuit and is used to set the control parameters of the flat accelerometer control circuit and collect experimental data from the flat accelerometer.

[0024] The first DC power supply, the second DC power supply, and the third DC power supply are respectively connected to the flat accelerometer measurement and control circuit, the cubic accelerometer measurement and control circuit, and the high-voltage drive module to provide them with DC operating voltage.

[0025] The flat accelerometer control circuit is connected to the high-voltage drive module and the vertical plate of the flat sensor. The flat accelerometer control circuit provides the control voltage for the vertical suspension of the flat sensor, which is amplified by the high-voltage drive module and applied to the vertical plate of the flat sensor.

[0026] The cubic accelerometer measurement and control circuit is connected to the flat accelerometer measurement and control circuit. The flat accelerometer measurement and control circuit provides the cubic accelerometer measurement and control circuit with the TTL demodulation signal required for its analog demodulation. At the same time, the cubic accelerometer measurement and control circuit is connected to the Y, Z1, and Z2 horizontal axis plates of the flat sensor for capturing and controlling the horizontal direction of the flat sensor.

[0027] The flat sensor is placed on a three-axis displacement stage, which is used to make fine adjustments to the attitude of the flat sensor and further adjust the magnitude of its horizontal gravitational acceleration component, so as to realize the capture control of the flat sensor's horizontal axis by the cubic accelerometer measurement and control circuit.

[0028] In this embodiment of the invention, the triaxial displacement stage consists of a calibration platform and three support columns, and its structure is as follows: Figure 2 As shown, the calibration platform is a triangular marble platform, and the three support columns are metal support columns with adjustable height by a spiral. The top of the support column is a spherical structure. The three corners of the marble platform that contact the support column are designed as semi-circular grooves (positioning grooves) to provide a constraint that matches the top shape of the support column and restrict the translation between the calibration platform and the support column.

[0029] During testing, the flat sensor is placed in the middle of the calibration platform. When high-pressure suspension control begins, the height of the three support columns is adjusted to be as consistent as possible. After the vertical axis is stabilized by high-pressure suspension, the horizontal axis of the flat sensor is servo-feedback controlled by fine-tuning the height of the support columns (by adjusting the height of the support columns, the gravitational acceleration component on the horizontal axis of the test mass is minimized, so that it can enter the capture range of the cube accelerometer measurement and control circuit).

[0030] like Figure 4 The diagram shows the specific composition of the flat accelerometer control circuit and the cubic accelerometer control circuit, as well as their functional relationship on the flat sensor.

[0031] The capacitive displacement acquisition ADC1 of the flat accelerometer measurement and control circuit uses the AD7767 chip, with a sampling rate set to 100kHz. After calculation by the digital controller 1, the feedback voltage is output to the high-voltage drive module and applied to the electrodes in the vertical axis direction of the flat sensor. The voltage of the high-voltage drive module is about 1000V, which is used to overcome the ground gravity and make the test mass suspend at the center of the electrode cage.

[0032] The capacitive displacement acquisition ADC2 of the cubic accelerometer measurement and control circuit uses the AD7767-2 chip, with a sampling rate set to 1.25kHz. After calculation by the digital controller 2, the feedback voltage is output to the low-voltage drive module. After passing through the filtering circuit, it is applied to the front-back and left-right electrodes in the horizontal axis direction of the flat sensor. The voltage of the low-voltage drive module is about 14V, which is used to compensate for the horizontal component of gravitational acceleration, so that the test mass can be stably suspended in the center position of the electrode cage in the horizontal axis direction. This realizes the closed-loop verification of the cubic accelerometer measurement and control circuit and the software control algorithm, which can significantly reduce the on-orbit risk of the cubic accelerometer.

[0033] This invention only involves ground testing of the measurement and control circuit in a cubic accelerometer, and does not involve the cubic sensor itself.

[0034] Example 2: The present invention provides a ground testing method for a cubic accelerometer measurement and control circuit, the process of which is as follows: Figure 4 As shown, the system provided in Embodiment 1 above was used for testing. The specific steps include four steps: system connection, power-on setting of the flat accelerometer measurement and control circuit, loading of the high-voltage drive module and vertical capture control, and power-on setting of the cubic accelerometer measurement and control circuit and horizontal capture control.

[0035] Before the test begins, according to Figure 1As shown in the test system, the first monitor is connected to the connector corresponding to the flat accelerometer control circuit, and the second monitor is connected to the connector corresponding to the cubic accelerometer control circuit. The first, second, and third DC power supplies are connected to the connectors corresponding to the flat accelerometer control circuit, the cubic accelerometer control circuit, and the high-voltage drive module, respectively. The high-voltage drive module is connected to the connector corresponding to the vertical control board of the flat accelerometer control circuit, which in turn is connected to the connector corresponding to the vertical electrode plate of the flat sensor. The cubic accelerometer control circuit is connected to the connector corresponding to the electrode plate of the flat sensor's horizontal axis (Y, Z1, Z2, this coordinate system is the instrument coordinate system, conforming to the right-hand Cartesian coordinate system). The TTL demodulated signal of the horizontal axis of the flat accelerometer control circuit is connected to the capacitive displacement analog demodulation circuit of the corresponding three test channels of the cubic accelerometer control circuit via an external coaxial interconnect cable.

[0036] Turn on the first monitor and the first DC power supply, establish communication between the first monitor and the flat accelerometer measurement and control circuit, and set the PID control parameters of the three vertical channels of the flat accelerometer measurement and control circuit and the output amplitude of the sinusoidal detection voltage Vd.

[0037] Turn on the button switches for the third DC power supply and the high-voltage drive module. Slowly rotate the gain adjustment knob of the high-voltage drive module to gradually increase the driving voltage of the vertical electrode plate of the flat sensor. Simultaneously observe the curve of the capacitive displacement detection voltage in the vertical direction (X1, X2, X3, this coordinate system is the instrument coordinate system) on the first monitor. When the capacitive displacement detection voltage in the vertical direction suddenly drops to 0V and fluctuates around 0V, it indicates that the vertical direction of the flat sensor has been captured and controlled. In the flat accelerometer, the vertical axis is defined as the X-axis, which includes three electrodes: X1, X2, and X3. By applying high voltage to these three electrodes, the mass block can be suspended and controlled at the center position of the electrode cage along the vertical axis.

[0038] Turn on the second monitor and the second DC power supply to establish communication between the second monitor and the cubic accelerometer control circuit. Set the PID control parameters for three channels of the cubic accelerometer control circuit (to ensure the comprehensiveness of the cubic accelerometer control circuit test and verification, its six channels X1, X2, Y1, Y2, Z1, and Z2 are divided into two groups, namely X1 / X2 / Y1 and Y2 / Z1 / Z2, which are tested separately). In the cubic accelerometer, each of its X, Y, and Z axes contains two channels, corresponding to X1, X2, Y1, Y2, Z1, and Z2. Their specific orientation is not strictly defined; they only need to correspond to the X, Y, and Z axes in the instrument coordinate system that conforms to the right-hand rule.

[0039] By observing the displacement curves of the horizontal axes (Y, Z1, Z2) of the flat sensor on the second monitor, it is generally found that the horizontal axis displacement of the flat sensor measured after direct connection is basically in a saturated state due to the small capture and measurement range of the electrostatic levitation accelerometer. The support column of the three-axis displacement stage needs to be slowly adjusted. If the displacement detection voltage of the flat sensor's horizontal axis displayed on the second monitor fluctuates around 0V after adjusting the displacement stage, it indicates that the capture control of the flat sensor's horizontal axis has been achieved. This proves that the hardware circuit, software function, and control algorithm of the cubic accelerometer measurement and control circuit meet the design requirements and realize the closed-loop control verification of the cubic accelerometer measurement and control circuit. If the flat sensor's horizontal axis cannot achieve stable levitation control, that is, the three-axis displacement cannot be adjusted to fluctuate around 0V, then the hardware circuit and software control algorithm of the cubic accelerometer need to be further investigated.

[0040] In summary, the above are merely preferred embodiments of the present invention and are 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 within the scope of protection of the present invention.

Claims

1. A ground testing system for a cubic accelerometer measurement and control circuit, characterized in that, The flat accelerometer measurement and control circuit, the cubic accelerometer measurement and control circuit, the high-voltage driving module, the flat sensor and the three-axis displacement table are included. The cubic accelerometer measurement and control circuit is connected with the flat accelerometer measurement and control circuit, and the flat accelerometer measurement and control circuit provides the TTL demodulation signal required by the cubic accelerometer measurement and control circuit for analog demodulation; the cubic accelerometer measurement and control circuit is connected with the horizontal electrode plate of the flat sensor, and the horizontal direction of the test mass of the flat sensor is controlled to the center position of the front and rear electrodes and the left and right electrodes through the cubic accelerometer measurement and control circuit. The flat accelerometer measurement and control circuit is connected with the high-voltage driving module, and the high-voltage driving module is connected with the vertical upper electrode plate of the flat sensor; the test mass of the flat sensor is suspended in the middle position of the upper and lower electrode plates in the vertical direction through the flat accelerometer. The flat sensor is placed on the three-axis displacement table, and the three-axis displacement table is used for adjusting the attitude of the flat sensor and adjusting the size of the horizontal gravity acceleration component, so as to realize the capture control of the cubic accelerometer measurement and control circuit on the horizontal axis of the flat sensor.

2. A ground test system for a cubic accelerometer measurement and control circuit as recited in claim 1, wherein, The first monitor and the second monitor are further included. The first monitor is used for communicating with the flat accelerometer measurement and control circuit, setting control parameters and storing data. The second monitor is used for communicating with the cubic accelerometer measurement and control circuit, setting control parameters and storing data.

3. A ground test system for a cubic accelerometer control circuit as in claim 1, wherein, The first DC power supply, the second DC power supply and the third DC power supply are further included. The first DC power supply, the second DC power supply and the third DC power supply provide the required DC voltage for the flat accelerometer measurement and control circuit, the cubic accelerometer measurement and control circuit and the high-voltage driving module respectively.

4. The ground test system for a cubic accelerometer measurement and control circuit according to any one of claims 1 to 3, characterized in that, The three-axis displacement table is composed of a calibration platform and three support columns; the calibration platform is a triangular marble platform, and the three support columns are metal support columns with adjustable height; the top of the support column is spherical, and the positions where the three corners of the marble platform contact with the support columns are designed as semicircular grooves, which are used for providing a constraint matched with the top shape of the support column and limiting the translation between the calibration platform and the support column.

5. A ground test system for a cubic accelerometer control circuit as recited in claim 4, wherein, During the test, the flat sensor is placed in the middle position of the calibration platform; when the high-voltage suspension control is started, the heights of the three support columns are adjusted to the same height; after the vertical axis is stably suspended by the high-voltage suspension, the height of the support column is adjusted so that the gravity acceleration component of the test mass horizontal axis enters the capture interval of the cubic accelerometer measurement and control circuit, and the servo feedback control of the horizontal axis of the flat sensor is realized.

6. A ground test system for a cubic accelerometer control circuit as recited in claim 4, wherein, The flat accelerometer measurement and control circuit includes a vertical axis capacitive displacement detection circuit, a capacitive displacement collection ADC1 and a digital controller 1. The capacitive displacement acquisition ADC1 selects AD7767 chip, and the sampling rate is set to 100 kHz. After calculation by the digital controller 1, the feedback voltage is output to the high-voltage driving module and applied to the electrode in the vertical axis direction of the flat sensor. The voltage of the high-voltage driving module is 1000 V, which is used to overcome the ground gravity and make the test mass suspended in the center of the electrode cage.

7. A ground test system for a cubic accelerometer control circuit as recited in claim 4, wherein, The cuboid accelerometer measurement and control circuit includes a horizontal axis capacitive displacement monitoring circuit, a capacitive displacement acquisition ADC2, a filter circuit, a low-voltage driving module, and a digital controller 2. The capacitive displacement acquisition ADC2 uses AD7767-2 chip, and the sampling rate is set to 1.25 kHz. After calculation by the digital controller 2, the feedback voltage is output to the low-voltage driving module and applied to the front-back and left-right electrodes in the horizontal axis direction of the flat sensor after the filter circuit. The voltage of the low-voltage driving module is 14 V, which is used to compensate the horizontal component of the gravity acceleration and make the test mass stably suspended in the center of the electrode cage in the horizontal axis direction, thereby realizing the closed-loop verification of the cuboid accelerometer measurement and control circuit and the software control algorithm.

8. A test method for a ground test system of a cubic accelerometer measurement and control circuit, characterized in that, The cuboid accelerometer ground test system according to claim 5, 6 or 7 is used to perform the following test steps: Step (1) turn on the first DC power supply, set the output voltage of the first DC power supply to the working voltage of the flat accelerometer, turn on the first monitor, open the upper computer communication software on the first monitor, establish communication between the first monitor and the flat accelerometer, and set the control parameters of the flat accelerometer through the first monitor; Step (2) turn on the third DC power supply, set the output voltage of the third DC power supply to the working voltage of the high-voltage driving module, turn on the high-voltage driving module, slowly open the knob switch of the high-voltage driving module, and observe the capacitive displacement monitoring curve on the first monitor at the same time. Whether the capacitive displacement detection voltage in the vertical direction fluctuates within the set range around 0 V is observed. When the capacitive displacement detection voltage in the vertical direction suddenly changes to 0 V and fluctuates within the set range around 0 V, it indicates that the vertical direction of the flat sensor has realized capture control; Step (3) turn on the second DC power supply, set the output voltage of the second DC power supply to the working voltage of the cuboid accelerometer measurement and control circuit, turn on the second monitor, open the upper computer communication software on the second monitor, establish communication between the second monitor and the cuboid accelerometer measurement and control circuit, set the control parameters of the cuboid accelerometer measurement and control circuit through the second monitor, and observe the capacitive displacement monitoring curve on the second monitor at the same time. Whether the capacitive displacement detection voltage in the horizontal direction fluctuates within the set range around 0 V is observed. When the capacitive displacement detection voltage in the horizontal direction fluctuates within the set range around 0 V, it indicates that the capture control of the horizontal axis of the flat sensor is realized.

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