Closed-loop measurement method and system for electronic temperature coefficient of space electrostatic accelerometer

Abstract

The invention belongs to the field of sensing test of an electrostatic accelerometer, and particularly discloses a closed-loop measurement method and system for an electronic temperature coefficient of a space electrostatic accelerometer. The system comprises a virtual probe, an electronics unit, a temperature probe, a temperature control box and a data processing unit, the virtual probe and the data processing unit are placed in a room temperature environment; the electronics unit and the temperature probe are placed in the temperature control box; the electronics unit is used for outputting feedback voltage according to the capacitance difference signal transmitted by the virtual probe; the temperature probe is used for measuring the environment temperature of the electronics unit in real time; and the data processing unit is used for acquiring the electronic temperature coefficient of the electrostatic accelerometer according to the environment temperature of the electronic unit and the feedback voltage output by the electronic unit at different temperatures. According to the invention, rapid measurement of the electronic temperature coefficient is realized.

Description

Technical Field

[0001] The present application belongs to the field of electrostatic accelerometer sensor testing, and more specifically, to a closed-loop measurement method and system for the electronics temperature coefficient of a space electrostatic accelerometer. Background Art

[0002] As a key payload in satellite gravity measurement and other related programs, high-precision electrostatic accelerometers based on capacitive displacement measurement and electrostatic feedback control technology have undergone long-term on-orbit verification and have been successfully used in various space exploration missions. Therefore, in-depth research on high-precision electrostatic accelerometers has become one of the important tasks in the field of space science.

[0003] The electrostatic accelerometer is mainly composed of a mechanical sensitive probe and a sensor control circuit. The mechanical sensitive probe is composed of a test mass and multiple capacitor plates, which can realize the detection and control of the capacitance displacement of six degrees of freedom. The sensor control circuit is composed of a capacitance displacement sensing circuit, a control circuit and a drive circuit, which can realize the conversion of the capacitance difference signal to the voltage signal and apply an electrostatic force of appropriate size. When the test mass is subjected to the external disturbance acceleration, the test mass will deviate from the original equilibrium position, so that the capacitance difference between the test mass surface and the plate pair facing it changes. The capacitance displacement sensing circuit can convert this capacitance difference signal into a corresponding voltage signal, and then measure the position of the test mass deviating from the equilibrium point. Then, this voltage signal is calculated by the controller to obtain a feedback voltage of appropriate size, which is fed back to the electrostatic actuator through the feedback drive circuit so that the test mass obtains a feedback voltage of appropriate size, and is fed back to the electrostatic actuator through the feedback drive circuit so that the test mass obtains an electrostatic force of appropriate size, so that the test mass maintains dynamic balance. Finally, the corresponding acceleration signal can be obtained by reading the voltage data fed back to the actuator.

[0004] As the core sensor in space exploration, the electrostatic accelerometer has extremely high resolution and sensitivity. Any environmental changes will affect its measurement results, among which temperature fluctuation is one of the key influencing factors. Therefore, the existing designs have set extremely strict requirements on the working temperature of the mechanical sensitive probe to ensure the accuracy of its measurement results. However, the parameters of the sensor control circuit used for signal extraction will also change due to its own heating and ambient temperature fluctuations, thus affecting the final output. Therefore, it is necessary to conduct an experimental evaluation of the temperature coefficient of the electronic unit. The traditional method of achieving ground closed-loop measurement of the temperature coefficient of the electrostatic accelerometer electronics requires the use of a ground torsion pendulum method to overcome the influence of gravity on the sensitive probe. This method is not only labor-intensive and inefficient, but also easily affected by ground vibrations. At the same time, it is also impossible to perform six-degree-of-freedom measurements. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a closed-loop measurement method and system for the temperature coefficient of the electronics of a space electrostatic accelerometer, aiming to solve the problem that the traditional method of achieving ground closed-loop measurement of the temperature coefficient of the electronics of an electrostatic accelerometer requires the use of a ground torsion pendulum method to overcome the influence of gravity on the sensitive probe, resulting in a large workload, low efficiency and susceptibility to ground vibration.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a closed-loop measurement system for the electronic temperature coefficient of a space electrostatic accelerometer, comprising: a virtual probe, an electronics unit, a temperature probe, a temperature control box and a data processing unit; The virtual probe and the data processing unit are placed in a room temperature environment; the electronic unit and the temperature probe are placed in a temperature control box; the virtual probe and the electronic unit are bidirectionally connected; the output ends of the temperature probe and the electronic unit are connected to the data processing unit; The electronic unit is used to output a feedback voltage according to the capacitance difference signal transmitted by the virtual probe; the temperature probe is used to measure the ambient temperature of the electronic unit in real time; the data processing unit is used to obtain the electronic temperature coefficient of the electrostatic accelerometer according to the ambient temperature of the electronic unit and the feedback voltage output by the electronic unit at different temperatures.

[0007] Further preferably, the electronics unit comprises: a capacitive displacement sensing circuit, a controller, a feedback drive circuit and a second analog-to-digital converter connected in sequence; the input end of the capacitive displacement sensing circuit is connected to the virtual probe; the output end of the feedback drive circuit is connected to the virtual probe; the input end of the second analog-to-digital converter is connected to the feedback drive circuit, and the output end is connected to the data processing unit; The capacitive displacement sensing circuit is used to measure the capacitance difference signal of the virtual probe and convert it into a voltage signal; the controller is used to calculate the feedback voltage according to the input voltage signal; the feedback driving circuit is used to apply the feedback voltage output by the controller to the virtual probe to calculate the magnitude of the electrostatic force.

[0008] Further preferably, the virtual probe comprises: an electrostatic actuator, a displacement conversion circuit, a capacitance conversion circuit, a first digital-to-analog conversion circuit, a first analog-to-digital conversion circuit, a first fixed capacitor, and a second fixed capacitor; The output end of the displacement conversion circuit is connected to the input end of the capacitance conversion circuit; the output end of the capacitance conversion circuit is connected to the first digital analog conversion circuit; the first fixed capacitor and the second fixed capacitor are connected in series to the capacitance displacement sensing circuit; the input end of the first analog digital conversion circuit is connected to the output end of the feedback drive circuit; the output end of the first analog digital conversion circuit is connected to the electrostatic actuator; The displacement conversion circuit is used to convert the acceleration deviation signal into a displacement signal; the capacitance conversion circuit is used to convert the displacement signal into a capacitance signal; the first digital-to-analog conversion circuit and the first fixed capacitor and the second fixed capacitor are used to output a capacitance difference signal; the first analog-to-digital analog circuit is used to collect feedback voltage; and the electrostatic actuator is used to convert the feedback voltage into a feedback acceleration signal.

[0009] Further preferably, the voltage signal of the capacitance displacement sensing circuit caused by the capacitance difference signal simulated by the virtual probe is:

[0010] in, is the gain of the capacitive displacement sensing circuit; is the carrier amplitude; Capacitance difference signal simulated by the virtual probe; is the angular frequency of the carrier; t For time.

[0011] In a second aspect, the present application provides a closed-loop measurement method for the temperature coefficient of electronics of a space electrostatic accelerometer, comprising the following steps: Based on the capacitance difference signal transmitted by the virtual probe, the electronics unit outputs a feedback voltage; The electronic temperature coefficient of the electrostatic accelerometer is obtained according to the ambient temperature of the electronic unit and the feedback voltage output by the electronic unit at different temperatures; The virtual probe and the data processing unit are arranged in a room temperature environment.

[0012] Further preferably, the method for obtaining the feedback voltage specifically comprises the following steps: Convert the capacitance difference signal of the virtual probe into a voltage signal and calculate the feedback voltage; The feedback voltage is applied to the virtual probe to calculate the electrostatic force.

[0013] Further preferably, the method for acquiring the capacitance difference signal specifically comprises the following steps: The input acceleration signal is subtracted from the feedback acceleration signal to obtain an acceleration deviation signal; The acceleration deviation signal is converted into a displacement signal, which is then combined with a fixed capacitor to be converted into a capacitance difference signal output by a virtual probe.

[0014] Further preferably, the voltage signal converted from the capacitance difference signal of the virtual probe is:

[0015] in, is the gain of the capacitive displacement sensing circuit; is the carrier amplitude; Capacitance difference signal simulated by the virtual probe; is the angular frequency of the carrier; t For time.

[0016] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The traditional electronic temperature coefficient measurement method requires the construction of a real mechanical sensitive probe, and it must overcome the influence of the earth's gravity and ground vibration, and is greatly constrained by environmental factors. Compared with the traditional test space electrostatic accelerometer electronic temperature coefficient, this application uses a semi-physical platform to simulate the real working state of the original mechanical sensitive probe, avoiding the dependence of the sensitive probe on the surrounding environment, and placing the virtual probe and the data processing unit in a room temperature environment, thereby eliminating the influence of temperature on the virtual probe and the data processing unit. Only the electronic unit is placed in a temperature control box, and the electronic temperature coefficient is quickly measured according to the ambient temperature of the electronic unit and the feedback voltage output by the electronic unit at different temperatures. Similarly, this method can be applied to all accelerometers of the same type. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a closed-loop measurement system of the temperature coefficient of electronics of a space electrostatic velocimeter provided in an embodiment of the present application; Figure 2 It is a schematic diagram of the working details of each link provided in the embodiment of the present application; Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the temperature control box; 2 is the virtual probe; 3 is the electronics unit; 4 is the temperature probe; 5 is the data processing unit. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0020] The terms “first”, “second” and the like in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects.

[0021] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0022] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0023] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0024] like Figure 1 As shown, the present application utilizes a semi-physical platform to simulate the working behavior of a mechanical sensitive probe (virtual probe 2) equivalent to that of a mechanical sensitive probe, so that the entire system operates in a closed-loop state. The virtual probe 2 is then placed at room temperature and the electronics unit 3 is placed in a temperature control box, thereby achieving a six-degree-of-freedom closed-loop measurement of the electronics temperature coefficient of the electrostatic accelerometer and quickly verifying the theoretical model of the electronics temperature coefficient.

[0025] like Figure 2 As shown, the closed-loop measurement system of the temperature coefficient of the space electrostatic accelerometer includes: a temperature control box 1, a virtual probe 2, an electronics unit 3, a temperature probe 4 and a data processing unit 5; the electronics unit 3 includes: a capacitive displacement sensing circuit, a controller and a feedback drive circuit; The virtual probe 2 is used to simulate the working behavior of a mechanical sensitive probe using a semi-physical platform; the capacitive displacement sensing circuit is used to measure the capacitance difference signal of the virtual probe and convert it into a voltage signal; the controller is used to calculate a feedback voltage of appropriate size applied to the electrode plate according to the input voltage, so as to maintain the sensitive probe in a dynamic equilibrium state; the feedback drive circuit is used to apply the output feedback voltage of the controller to the virtual probe, so as to calculate the corresponding electrostatic force; the temperature control box 1 is used to control the ambient temperature; the temperature probe 4 is used to measure the ambient temperature in real time.

[0026] The present application provides a closed-loop measurement method for the temperature coefficient of electronics. The core of the method is to use a semi-physical platform to replace the mechanical sensitive probe equivalently, so that the entire system works in a closed-loop state. On the basis of a stable working state, the virtual probe is placed at room temperature, the electronic unit is placed in a temperature control box, and the size of the temperature control box is changed to achieve the purpose of closed-loop measurement of the temperature coefficient of the electronics of the electrostatic accelerometer.

[0027] Example Closed-loop measurement system for temperature coefficient of electronics Figure 1As shown, only the single-degree-of-freedom model test is used here for illustration. The virtual probe simulates the behavior of the real mechanical sensitive probe. The electronic unit extracts the capacitance difference signal of the virtual probe, and then applies it to the virtual probe after passing through the controller and the feedback drive circuit, thereby realizing closed-loop operation. At this time, the virtual probe is placed outside the temperature control box, and the electronic unit is placed inside the temperature control box for temperature cycle testing. The data processing unit collects the closed-loop output data in real time to realize the measurement of the electronic temperature coefficient. More specifically, Figure 2 As shown in the figure, the virtual probe set on the semi-physical platform includes: a displacement conversion circuit for converting the acceleration signal deviation into a displacement signal; a capacitance conversion circuit for converting the displacement signal into a capacitance signal; a DAC and a fixed capacitance difference for completing the output of the virtual probe capacitance difference signal; an ADC for collecting feedback voltage; an electrostatic actuator link for converting the voltage signal into a feedback acceleration signal; Figure 2 It can be seen that the open-loop output voltage of the capacitance displacement sensing circuit caused by the capacitance difference change simulated by the virtual probe is: (1) in: (2) The carrier signal Used to perform amplitude modulation on weak signals; the weak signals are input acceleration signals; The capacitance difference introduced by the input acceleration signal; is the gain of the capacitive displacement sensing circuit; is the carrier amplitude; is a first fixed capacitor; is the second fixed capacitor; An amplitude modulated signal generated for a semi-physical platform; is a fixed capacitance difference, Virtual capacitance values ​​generated for semi-physical platforms; is the angular frequency of the carrier; Formula (1) is the open-loop output of displacement sensing when the virtual probe is working. By selecting a suitable fixed capacitance difference , the virtual capacitance difference Simulate the behavior of real mechanosensitive probes: (3) Furthermore, the device can realize closed-loop control of the entire system of the electrostatic accelerometer, and then the electronic temperature coefficient can be measured in a closed loop.

[0028] More specifically, the final closed-loop measured acceleration can be obtained as:

[0029] Therefore, when the ambient temperature changes, we can get:

[0030] in, k is the closed-loop gain of the input acceleration, is the zero bias acceleration of the system. More specifically, It is just a zero bias caused by the non-ideal parameters of components in each circuit in the electronic unit, which will change with temperature; the closed-loop system still has a small output under zero input; T is the ambient temperature in the temperature control box; it can be seen that changes in temperature will lead to changes in the final measurement results, thereby realizing the measurement of the temperature coefficient.

[0031] Compared with the traditional test of the electronic temperature coefficient of the space electrostatic accelerometer, the traditional electronic temperature coefficient measurement method requires the construction of a real mechanical sensitive probe, and has to overcome the influence of the earth's gravity and ground vibration, and is greatly constrained by environmental factors. This application uses a semi-physical platform to simulate the real working state of the original mechanical sensitive probe, avoiding dependence on the surrounding environment, thereby realizing the rapid measurement of the electronic temperature coefficient. Similarly, this method can be applied to all accelerometers of the same type.

[0032] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0033] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0034] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0035] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0036] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A closed-loop measurement system for the temperature coefficient of electronics of a space electrostatic accelerometer, characterized in that: include: Virtual probe, electronics unit, temperature probe and data processing unit; The virtual probe and the data processing unit are placed in a room temperature environment; the electronic unit and the temperature probe are placed in a temperature control box; the virtual probe and the electronic unit are bidirectionally connected; the output ends of the temperature probe and the electronic unit are connected to the data processing unit; The temperature probe is used to measure the ambient temperature of the electronic unit in real time; the data processing unit is used to obtain the electronic temperature coefficient of the electrostatic accelerometer according to the real-time temperature of the temperature control box and the feedback voltage output by the electronic unit at different temperatures.

2. The closed-loop measurement system according to claim 1, characterized in that: The electronics unit includes: a capacitive displacement sensing circuit, a controller, a feedback driving circuit and a second analog-to-digital converter connected in sequence; the input end of the capacitive displacement sensing circuit is connected to the virtual probe; the output end of the feedback driving circuit is connected to the virtual probe; the input end of the second analog-to-digital converter is connected to the feedback driving circuit, and the output end is connected to the data processing unit; The capacitive displacement sensing circuit is used to measure the capacitance difference signal of the virtual probe and convert it into a voltage signal; the controller is used to calculate the feedback voltage according to the input voltage signal; the feedback driving circuit is used to apply the feedback voltage output by the controller to the virtual probe to calculate the magnitude of the electrostatic force.

3. The closed-loop measurement system according to claim 2, characterized in that: The virtual probe includes: an electrostatic actuator, a displacement conversion circuit, a capacitance conversion circuit, a first digital-to-analog conversion circuit, a first analog-to-digital conversion circuit, a first fixed capacitor, and a second fixed capacitor; The output end of the displacement conversion circuit is connected to the input end of the capacitance conversion circuit; the output end of the capacitance conversion circuit is connected to the first digital analog conversion circuit; the first fixed capacitor and the second fixed capacitor are connected in series to the capacitance displacement sensing circuit; the input end of the first analog digital conversion circuit is connected to the output end of the feedback drive circuit; the output end of the first analog digital conversion circuit is connected to the electrostatic actuator; The displacement conversion circuit is used to convert the acceleration signal deviation into a displacement signal; the capacitance conversion circuit is used to convert the displacement signal into a capacitance signal; the first digital-to-analog conversion circuit and the first fixed capacitor and the second fixed capacitor are used to output a capacitance difference signal; the first analog-to-digital analog circuit is used to collect feedback voltage; and the electrostatic actuator is used to convert the feedback voltage into a feedback acceleration signal.

4. The closed-loop measurement system according to claim 3, characterized in that: The voltage signal of the capacitive displacement sensing circuit caused by the capacitance difference signal of the virtual probe is: in, is the gain of the capacitive displacement sensing circuit; is the carrier amplitude; Capacitance difference signal simulated by the virtual probe; is the angular frequency of the carrier; t For time.

5. A closed-loop measurement method for the electronic temperature coefficient of a spatial electrostatic accelerometer based on the closed-loop measurement system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Based on the capacitance difference signal transmitted by the virtual probe, the electronics unit outputs a feedback voltage; The electronic temperature coefficient of the electrostatic accelerometer is obtained according to the ambient temperature of the electronic unit and the feedback voltage output by the electronic unit at different temperatures; The virtual probe and the data processing unit are arranged in a room temperature environment.

6. The closed-loop measurement method according to claim 5, characterized in that: The method for obtaining the feedback voltage specifically includes the following steps: Convert the capacitance difference signal of the virtual probe into a voltage signal and calculate the feedback voltage; The feedback voltage is applied to the virtual probe to calculate the electrostatic force.

7. The closed-loop measurement method according to claim 5 or 6, characterized in that: The method for obtaining the capacitance difference signal specifically comprises the following steps: The input acceleration signal is subtracted from the feedback acceleration signal to obtain an acceleration deviation signal; The acceleration deviation signal is converted into a displacement signal, which is then combined with a fixed capacitor to be converted into a capacitance difference signal output by a virtual probe.

8. The closed-loop measurement method according to claim 6, characterized in that: The voltage signal converted from the capacitance difference signal of the virtual probe is: in, is the gain of the capacitive displacement sensing circuit; is the carrier amplitude; Capacitance difference signal simulated by the virtual probe; is the angular frequency of the carrier; t For time.

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