Micro-thrust measurement device and measurement method

Abstract

The present invention relates to the technical field of micro-thrust measurement of aerospace micro-thrusters, and discloses a micro-thrust measurement device and a measurement method. The micro-thrust measurement device includes a superconducting magnetic suspension vibration isolation platform and a micro-thrust measurement device, and the micro-thrust measurement device is carried by a superconducting magnetic suspension vibration isolation platform for preliminarily isolating environmental noise. The micro-thrust measurement device has a reference signal output unit and a measured signal output unit with consistent structural and dynamic property parameters, so as to output a reference signal and a measured signal respectively. An effective micro-thrust signal is obtained based on the measured signal and the reference signal. The reference signal output unit and the measured signal output unit are symmetrically arranged, and are both suspended by flexible springs with adjustable thickness and detachable, and are respectively configured with dampers to further avoid interference of external noise on the reference signal and the measured signal. The present invention can effectively suppress the influence of environmental noise and improve the accuracy of micro-thrust measurement.

Description

Technical Field

[0001] The invention relates to the technical field of tiny thrust measurement of aerospace micro-thrusters, and in particular to a micro-thrust measurement device and a measurement method. Background Art

[0002] Space micro-thrusters are used for high-precision attitude and orbit control of spacecraft. Their thrust is often small and belongs to the category of weak force measurement. Therefore, in order to accurately obtain the propulsion performance of space thrusters, it is necessary to accurately measure the tiny thrust they generate. In the field of space micro-propulsion, micro-thrust measurement technology plays a vital role. It can not only truly and intuitively reflect the influence of control parameters and working process parameter changes on thruster propulsion performance, but also provide necessary support for the optimization design of thrusters.

[0003] However, if we want to achieve high-precision measurement of micro-thrust of aerospace thrusters, there are often many difficulties such as extremely small thrust-to-weight ratio, strong noise interference, vacuum testing, etc. Based on this, it is urgent to propose a device and method that can effectively suppress noise to achieve high-precision micro-thrust measurement. Summary of the invention

[0004] The object of the present invention is to provide a micro-thrust measurement device and a measurement method. The dual-system differential mode suppression method, superconducting magnetic levitation technology, eddy current damper and the like are used to separate and decouple external noise from effective micro-thrust information, thereby reducing the adverse effect of external noise on the micro-thrust measurement result. In addition, a bearing plate for bearing the thruster is a lightweight swing arm, which is suspended by a flexible spring sheet, so that the micro-thrust measurement device has a higher fixed frequency, which can not only realize wide-band measurement, but also has a higher bearing capacity.

[0005] In a first aspect, the present invention provides a micro-thrust measurement device, comprising:

[0006] Superconducting magnetic levitation vibration isolation platform,

[0007] and a micro-thrust measurement device, wherein the micro-thrust measurement device is carried by the superconducting magnetic levitation vibration isolation platform, and the superconducting magnetic levitation vibration isolation platform is used to isolate environmental noise; the micro-thrust measurement device has a reference signal output unit and a measured signal output unit with consistent structure and dynamic property parameters, so as to output a reference signal and a measured signal respectively, and the dynamic property parameters at least include a stiffness coefficient, an inertia coefficient and a damping coefficient; an effective micro-thrust signal is obtained based on the measured signal and the reference signal; and the reference signal output unit and the measured signal output unit are respectively configured with dampers to avoid interference of external noise on the reference signal and the measured signal.

[0008] As a possible implementation method, the reference signal output unit and the measured signal output unit are symmetrically arranged and are both suspended by flexible spring sheets; the flexible spring sheets are detachable, and the relationship between the thickness of the flexible spring sheets and the stiffness coefficient and load-bearing capacity of the micro-thrust measurement device is determined; flexible spring sheets of different thicknesses are replaced according to the stiffness coefficient and load-bearing capacity required by the micro-thrust measurement device to form a micro-thrust measurement device with multiple gears.

[0009] As a possible implementation manner, the thickness of the flexible spring sheet is smaller than the thickness of the component on which it is suspended, and the thickness of the component on which the flexible spring sheet is suspended is larger than the thickness of the flexible spring sheet.

[0010] As a possible implementation method, the flexible spring piece is made of a material with a hardness greater than or equal to 36HRC, an elastic modulus greater than or equal to 133GPa, a yield limit greater than or equal to 1037MPa, a fatigue limit greater than or equal to 750MPa, a tensile strength greater than or equal to 1106GPa, and a corrosion resistance coefficient less than 0.005mm / a.

[0011] As a possible implementation manner, the flexible spring piece is made of beryllium bronze, carbon spring steel, chromium-molybdenum spring steel, silicon-manganese spring steel, vulcanized spring steel, molybdenum spring steel or nickel alloy spring steel.

[0012] As a possible implementation, the micro-thrust measurement device also includes a laser interferometer and a differential system response collector; wherein the differential system response collector is used to obtain a reference signal and a measured signal output by a reference signal output unit and a measured signal output unit respectively, and further obtain a first differential signal based on the reference signal and the measured signal; the first differential signal is used to calibrate the laser interferometer; the laser interferometer is used to obtain a second differential signal between the reference signal output unit and the measured signal output unit, and further obtain a measurement value of the micro-thrust measurement device based on the second differential signal.

[0013] As a possible implementation, the two flexible spring sheets are suspended on a partition of a leveling platform included in the micro-thrust measurement device, and the expansion rate of the partition is less than or equal to 10 -7 K -1 .

[0014] As a possible implementation, the damper is a dual eddy current damper; each of the dual eddy current dampers includes a guide rail, a yoke pair supported by the guide rail, a permanent magnet pair arranged on the opposite end faces of the yoke pair, and a damping plate suspended at the lower end of the reference signal output unit or the measured signal output unit, and the tail of the damping plate is located in the air gap between the permanent magnet pair.

[0015] In a second aspect, the present invention provides a measurement method. Before executing the measurement method, the reference signal output unit and the measured signal output unit included in the micro-thrust measurement device described in claim 9 are identified for dynamic property parameters, that is, first, an electronic balance is used to calibrate the optimal relative position relationship between the permanent magnet and the coil and the driving control equation between the current passing through the coil and the electromagnetic force; then, according to the driving control equation, a known calibration force is applied to the reference signal output unit and the measured signal output unit, and the dynamic property parameters are obtained by inverting the measured system response to complete the identification of the dynamic property parameters of the reference signal output unit and the measured signal output unit; the micro-thrust measurement device is leveled using a leveling platform; the reference signal output unit and the measured signal output unit are adjusted so that the two have consistent dynamic property parameters, that is, they have the same stiffness coefficient, inertia coefficient and damping coefficient; the measurement method comprises the following steps:

[0016] Control the superconducting magnetic suspension vibration isolation platform to keep the suspension workbench where the micro-thrust measurement device is located in a stable suspension state;

[0017] Starting the measured signal output unit to bend the flexible spring sheet of the hoisted measured signal output unit;

[0018] Using a laser interferometer to obtain a differential signal between a reference signal output unit and a measured signal output unit, wherein the differential signal is a system response;

[0019] The micro-thrust is calculated based on the system response, the stiffness coefficient, the distance from the central axis of the thruster nozzle included in the measured signal output unit to the center line of the flexible spring, and the distance from the central axis of the laser interferometer to the center line of the flexible spring.

[0020] Compared with the prior art, the present invention has the following effects:

[0021] 1. The micro-thrust measurement device provided by the present invention uses a superconducting magnetic suspension vibration isolation platform to initially weaken external noise, and further attenuates external noise by configuring a damper in the reference signal output unit and the measured signal output unit, and then performs differential processing on the measured signal and the reference signal to subtract the external noise. Through the design of the superconducting magnetic suspension vibration isolation platform, the damper and the signal differential processing, the influence of external noise is effectively suppressed and the accuracy of micro-thrust measurement is improved.

[0022] 2. The micro-thrust measurement device provided by the present invention adopts a flexible spring sheet with adjustable thickness and replaceable thickness, which can change the stiffness coefficient and load-bearing capacity of the micro-thrust measurement device, forming a multi-speed micro-thrust measurement device, thereby meeting the measurement needs of thrusts of different magnitudes and expanding the scope of application.

[0023] 3. The micro-thrust measurement device provided by the present invention adopts a reference signal output unit and a measured signal output unit with consistent structural and dynamic property parameters, so that the two units are affected by external noise in the same way. The reference signal output unit is used as a reference, and the measured signal output unit measures the micro-thrust, and then the obtained measured signal and the reference signal are differentially processed, so as to separate and decouple the effective thrust from the environmental noise, thereby obtaining the effective signal corresponding to the micro-thrust.

[0024] 4. In the micro-thrust measurement device provided by the present invention, the partition of the leveling platform is made of a material with a low thermal expansion coefficient and good overall uniformity, so that the micro-thrust measurement device will not produce errors due to temperature influence, which helps to improve the stability and measurement accuracy of the micro-thrust measurement device.

[0025] 5. In the micro-thrust measurement device provided by the present invention, both the reference signal output unit and the measured signal output unit are configured with a dual eddy current damper. By adjusting the electric translation stage carrying the dual eddy current damper and the dovetail groove guide of the dual eddy current damper, the positional relationship between the permanent magnet pair and the damping plate can be changed, thereby providing different damping ratios for the micro-thrust measurement device, so that the micro-thrust measurement device has adjustable damping properties, which can not only adapt to the suppression of environmental noise with different bandwidths and improve measurement accuracy, but also adjust the appropriate system response overshoot according to the range and weight of the thruster being measured, effectively shorten the system transient process and improve measurement efficiency.

[0026] 6. In the micro-thrust measurement device provided by the present invention, both the reference signal output unit and the measured signal output unit are configured with an electromagnetic force source. The positional relationship between the DC coil and the permanent magnet can be adjusted by adjusting the electric translation stage carrying the electromagnetic force source, thereby providing the required high-precision calibration force source for the micro-thrust measurement device.

[0027] 7. The present invention obtains a reference signal and a measured signal through a differential system response collector, and debugs a micro-thrust measurement device including a laser interferometer based on the reference signal and the measured signal. When the micro-thrust measurement device reaches the optimal working state, displacement measurement is performed through laser interferometer measurement. Such an arrangement can greatly improve the measurement accuracy of the present invention, thereby enabling high-precision measurement of tiny thrusts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 The general assembly diagram of the micro-thrust measurement device provided by the embodiment of the present invention;

[0030] Figures 2 to 3 A schematic structural diagram of a micro-thrust measurement device provided in an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the structure of a damper and an electromagnetic force source of a micro-thrust measurement device provided in an embodiment of the present invention;

[0032] Figure 5 A schematic diagram of the structure of a support assembly of a micro-thrust measurement device provided by an embodiment of the present invention;

[0033] Figure 6 A schematic diagram of the structure and installation position of a leveling platform of a micro-thrust measurement device provided in an embodiment of the present invention;

[0034] Figure 7 A schematic diagram of the differential system response collector structure and installation position of the micro-thrust measurement device provided in an embodiment of the present invention.

[0035] Reference numerals:

[0036] 10-superconducting magnetic suspension vibration isolation platform, 100-fixed substrate, 101-suspended substrate, 102-floating unit, 103-refrigerator, 104-superconducting magnetic suspension unit;

[0037] 11-micro-thrust measuring device, 110-reference signal output unit, 111-measured signal output unit, 1110-measured thruster, 1111-carrying member; 112-damper, 1120-guide rail, 1121-yoke pair, 1122-permanent magnet pair, 1123-damping plate; 113-first electric displacement stage; 114-support assembly, 1140-bottom platform, 1141-middle platform, 1142-upper platform, 1143-top platform, 1144-bottom support column, 1145-middle support column, 1146-top support column; 115-leveling platform, 1150-partition, 1151-level meter, 1152-lifting adjustment bolt; 116-flexible spring sheet; 117-connecting piece; 118- T-plate; 119-laser interferometer, 1190-laser, 1191-optical lens;

[0038] 120-differential system response collector, 1200-fixed part, 1201-displacement sensor, 1202-plate, 1203-second electric displacement stage; 121-electromagnetic force source, 1210-permanent magnet, 1211-DC coil; 122-third electric displacement stage;

[0039] 13- Vacuum chamber. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention 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 invention and are not intended to limit the present invention.

[0041] It should be noted that when an element is referred to as being "fixed on" or "set on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, 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 present invention.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In the field of aerospace micro-propulsion, micro-thrust measurement technology can not only truly and intuitively reflect the influence of control parameters and working process parameter changes on thruster propulsion performance, but also provide necessary support for the optimization design of thrusters. Its importance is self-evident. However, the actual high-precision measurement of micro-thrust often has many difficulties such as extremely small thrust-to-weight ratio, strong noise interference, and vacuum testing. In order to achieve high-precision micro-thrust measurement and suppress noise influence, the embodiment of the present invention proposes a micro-thrust measurement device and a measurement method, which can separate and decouple environmental noise from micro-thrust effective information by using a dual-system differential mode suppression method, superconducting magnetic suspension technology, eddy current damper, etc., thereby reducing the adverse effect of environmental noise on micro-thrust measurement results; in addition, the bearing plate used to carry the thruster is a lightweight swing arm, which is hoisted by a flexible spring sheet, so that the micro-thrust measurement device has a higher fixed frequency, which can not only realize broadband measurement, but also has a higher carrying capacity. Furthermore, in practical applications, the present invention uses a Fabry-Perot laser interferometer to directly obtain the differential mode signal of the measured signal and the reference signal. Since the Fabry-Perot laser interferometer has a higher resolution than other signal measurement devices / systems, it can achieve the measurement of tiny thrusts, so that the micro-thrust measurement device provided by the embodiment of the present invention has a larger range and a wider measurement range. The Fabry-Perot laser interferometer is composed of a laser and two parallel glass plates or quartz plates with a certain reflectivity. The parallel glass plates or quartz plates are integrated on the micro-thrust measurement device to form an optical cavity with the intermediate dielectric layer. The laser can be installed on a multi-degree-of-freedom displacement platform, and has the characteristics of compact structure and high integration.

[0046] In a first aspect, an embodiment of the present invention provides a micro-thrust measurement device, see Figure 1 The micro-thrust measurement device includes: a superconducting magnetic suspension vibration isolation platform 10 and a micro-thrust measurement device 11. The micro-thrust measurement device 11 is carried by the superconducting magnetic suspension vibration isolation platform 10 and is used to isolate external noise. In actual application, the micro-thrust measurement device 11 is vertically collinear with the superconducting magnetic suspension vibration isolation platform 10 to ensure that the micro-thrust measurement device 11 can be stably suspended. The measurement device can work in a vacuum environment, for example, a vacuum chamber 13, or in a non-vacuum environment.

[0047] See also Figure 1As an example, the superconducting magnetic suspension vibration isolation platform 10 includes a fixed substrate 100, a suspended substrate 101, a floating unit 102, two identical refrigerators 103 and two identical superconducting magnetic suspension units 104. The fixed substrate 100 and the suspended substrate 101 have the same shape and are vertically collinear. Each superconducting magnetic suspension unit 104 includes a permanent magnet ring and a superconductor array that are relatively arranged up and down. Among them, the two refrigerators 103 are relatively arranged below the fixed substrate 100, and the floating unit 102 and the two superconducting magnetic suspension units 104 are located above the fixed substrate 100. The bottom end surface of the floating unit 102 is fixedly arranged at the center position of the fixed substrate 100, and the top end surface of the floating unit 102 supports the suspended substrate 101. The micro-thrust measurement device 11 is located on the suspended substrate 101 and is vertically collinear with the suspended substrate 101. When the refrigerator 103 cools the superconducting magnetic suspension unit 104 to a certain temperature, the superconducting magnetic suspension unit 104 causes the suspension substrate 101 to rise, thereby driving the micro-thrust measurement device 11 to rise and break away from the support of the floating unit 102, so that the micro-thrust measurement device 11 will not be affected by external vibration noise, thereby achieving the purpose of blocking environmental noise.

[0048] See also Figures 2 to 3 , the micro-thrust measuring device 11 has a reference signal output unit 110 and a measured signal output unit 111 with consistent structures and dynamic property parameters, that is, the reference signal output unit 110 and the measured signal output unit 111 are exactly the same. The above-mentioned dynamic property parameters at least include stiffness coefficient, inertia coefficient and damping coefficient. The reference signal output unit 110 and the measured signal output unit 111 both include a thruster 1110 to be measured and a bearing 1111, and the reference signal output unit 110 and the measured signal output unit 111 output a reference signal and a measured signal respectively. The measured signal and the reference signal are obtained and differentially processed to obtain an effective micro-thrust signal. The reference signal output unit 110 and the measured signal output unit 111 have consistent structures and dynamic property parameters, indicating that the two units are uniformly affected by external noise, and the obtained measured signal and the reference signal are differentially processed to subtract the influence caused by external noise, thereby obtaining an effective micro-thrust signal.

[0049] See also Figure 3 to Figure 4, the reference signal output unit 110 and the measured signal output unit 111 are respectively configured with a damper 112 to avoid interference of external noise on the reference signal and the measured signal. Exemplarily, the damper 112 is a double eddy current damper. Each damper 112 includes a guide rail 1120, a yoke pair 1121 carried by the guide rail 1120, a permanent magnet pair 1122 arranged on the opposite end faces of the yoke pair 1121, and a damping plate 1123 suspended at the lower end of the reference signal output unit 110 or the measured signal output unit 111, and the tail of the damping plate 1123 is located in the air gap between the permanent magnet pair 1122. The damper 112 can be wrapped with magnetic shielding materials such as Permalloy to reduce the magnetic field pollution of the permanent magnet pair 1122. Exemplarily, the guide rail 1120 is a dovetail groove guide rail. The magnetic field strength between the permanent magnet pair 1122 can be adjusted through the dovetail groove guide rail and the first electric displacement stage 113 included in the micro-thrust measurement device 11. Combined with the damping plate 1123 located at the tail of the plate in the air gap between the permanent magnet pair 1122, the positional relationship between the permanent magnet pair 1122 and the damping plate 1123 can be changed, so that different damping effects can be achieved, so that the damping properties of the micro-thrust measurement equipment can be adjusted, thereby further reducing the impact of high-frequency noise and improving measurement accuracy.

[0050] The micro-thrust measurement device provided in this embodiment uses a superconducting magnetic suspension vibration isolation platform 10 to initially weaken external noise, and further absorbs and attenuates external noise by configuring a damper 112 in a reference signal output unit 110 and a measured signal output unit 111, and then performs differential processing on the measured signal and the reference signal to subtract the external noise. Through the design of the superconducting magnetic suspension vibration isolation platform, the damper and the signal differential processing, the influence of external noise can be effectively suppressed and the accuracy of micro-thrust measurement can be improved.

[0051] See also Figures 2 to 7 As a possible implementation, the micro-thrust measurement device 11 also includes a support assembly 114, a leveling platform 115, two flexible springs 116, two connectors 117, a T-plate 118, a laser interferometer 119, a differential system response collector 120 and an electromagnetic force source 121.

[0052] See also Figure 2 and Figure 5The support assembly 114 includes a bottom platform 1140 , a middle platform 1141 , an upper platform 1142 , a top platform 1143 , a bottom support column 1144 , a middle support column 1145 and a top support column 1146 . Among them, the top platform 1143, the top support column 1146, the upper platform 1142, the middle support column 1145, the middle platform 1141, the bottom support column 1144, and the bottom platform 1140 are stacked from top to bottom; the bottom platform 1140 is fixedly installed on the suspended substrate 101, and the four bottom support columns 1144 are vertically installed at the four corners of the bottom platform 1140, and the upper ends of the four bottom support columns 1144 are connected to the middle platform 1141 by bolts; the four middle support columns 1145 are vertically installed on the middle platform 1141, and the upper ends of the middle support columns 1145 are connected to the upper platform 1142 by bolts; the four top support columns 1146 are vertically installed on the upper platform 1142, and the upper ends of the top support columns 1146 are connected to the top platform 1143 by bolts. Furthermore, the height of the middle support column 1145 is greater than that of the bottom support column 1144, and the height of the bottom support column 1144 is greater than that of the top support column 1146, so that the structure of the support assembly 114 is stable; and each support column and each platform is a thickened structure that is not easy to deform, which can improve the load-bearing capacity and eliminate the measurement error caused by deformation.

[0053] See also Figure 6 The leveling platform 115 includes a partition 1150, a leveler 1151 and a lifting adjustment bolt 1152. The partition 1150 is made of a material with a low thermal expansion coefficient and good overall uniformity, such as low thermal expansion microcrystalline glass or invar alloy, so that the expansion coefficient of the partition 1150 is less than or equal to 10 -7 K -1 Such a design prevents the partition 1150 from being deformed due to temperature, thus ensuring the stability of the micro-thrust measurement device. The partition 1150 is connected to the top platform 1143 through three lifting adjustment bolts 1152. The level of the partition 1150 is adjusted by adjusting the lifting adjustment bolts 1152. During the adjustment process, the level meter 1151 is used to detect the level of the partition 1150 to ensure that the partition 1150 can be adjusted to the best level.

[0054] See also Figure 3, two flexible spring sheets 116 are respectively hoisted at opposite ends of the partition 1150 through two connecting pieces 117, and the reference signal output unit 110 and the measured signal output unit 111 are symmetrically arranged, and are both hoisted below the flexible spring sheet 116 through the bearing piece 1111. The flexible spring sheet 116 is detachable, and a finite element numerical analysis is performed on the thickness of the flexible spring sheet 116 and the stiffness coefficient and bearing capacity of the micro-thrust measuring device 11 to determine the corresponding relationship between the thickness of the flexible spring sheet 116 and the stiffness coefficient and bearing capacity, see Table 1 for details. In practical applications, the flexible spring sheets 116 of different thicknesses can be replaced according to the stiffness coefficient and bearing capacity required by the micro-thrust measuring device 11 to form a micro-thrust measuring device 11 with multiple gears.

[0055] Table 1 Corresponding relationship between the thickness of the flexible spring and the stiffness coefficient and load-bearing capacity of the micro-thrust measurement device

[0056]

[0057] Exemplarily, the thickness of the flexible spring sheet 116 is smaller than the thickness of the component hoisted by it, i.e. the thickness of the bearing member 1111. The component hoisting the flexible spring sheet 116, i.e. the thickness of the connecting member 117 is larger than the thickness of the flexible spring sheet 116. That is, compared with the connecting member 117 and the bearing member 1111, the thickness of the flexible spring sheet 116 is minimum, so that under the action of external force, only the flexible spring sheet 116 will bend, and the measurement accuracy can be guaranteed to the greatest extent. In addition, the flexible spring sheet 116 is detachably connected with the connecting member 117 and the bearing member 1111, for example, bolted, and easy to disassemble. Therefore, the flexible spring sheet 116 of different thicknesses can be replaced according to the stiffness coefficient and the load-bearing capacity required by the micro-thrust measuring device 11, so that the micro-thrust measuring device 11 has a multi-gear adjustable function, which can be applicable to different micro-thrust measurement requirements and expand a wider range of application scenarios.

[0058] As a possible implementation method, the flexible spring piece 116 is made of a material with a hardness greater than or equal to 36HRC, an elastic modulus greater than or equal to 133GPa, a yield limit greater than or equal to 1037MPa, a fatigue limit greater than or equal to 750MPa, a tensile strength greater than or equal to 1106GPa, and a corrosion resistance coefficient less than 0.005mm / a.

[0059] As an example, the flexible spring sheet 116 is made of beryllium bronze, carbon spring steel, chrome-molybdenum spring steel, silicon-manganese spring steel, vulcanized spring steel, molybdenum spring steel or nickel alloy spring steel.

[0060] See also Figure 3 , Figure 4 and Figure 7As a possible implementation, the T-plate 118 is connected to the lower end of the carrier 1111. The laser interferometer 119 includes a laser 1190 and two optical lenses 1191. The optical lenses 1191 can be made of a glass plate or a quartz plate with a certain reflectivity. The two optical lenses 1191 are relatively arranged on the T-plate 118 to form an optical cavity with the medium in the middle. Specifically, when the thrust acts on the laser interferometer 119, it will cause a slight displacement of the optical lens 1191 of the laser interferometer 119. This slight displacement will cause the optical path difference generated by multiple reflections of the laser in the laser interferometer 119 to change; since the change in the optical path difference is directly related to the displacement of the interference fringes, the displacement caused by the thrust can be measured by observing the movement of the interference fringes; further, since there is a definite relationship between the thrust and the displacement, the magnitude of the thrust is indirectly measured by measuring the displacement.

[0061] As an example, the laser interferometer 119 may be a Fabry-Perot laser interferometer, which is usually used as a high-sensitivity displacement sensor.

[0062] In the embodiment of the present invention, a Fabry-Perot laser interferometer is used to directly obtain a differential signal of a measured signal and a reference signal. Since the Fabry-Perot laser interferometer has a higher resolution than other signal measurement devices / systems, it can measure tiny thrusts, so that the micro-thrust measurement device provided by the embodiment of the present invention has a larger range and a wider measurement range.

[0063] In addition, the parallel glass plates (or quartz plates) included in the Fabry-Perot laser interferometer are suspended by the T-plate 118 included in the micro-thrust measurement device, which has the characteristics of compact structure and high integration.

[0064] See also Figure 7, the differential system response collector 120 includes two fixings 1200, two displacement sensors 1201, pole plates 1202 corresponding to the two displacement sensors, and two second electric displacement stages 1203. Exemplarily, the pole plates 1202 and the optical lenses 1191 are both circular, and the centers of the two pole plates 1202 and the two optical lenses 1191 are located in the same horizontal plane. The two displacement sensors 1201 are respectively mounted on two fixings 1200, and the fixings 1200 have two circular rings of different sizes, which can fix sensor probes with different ranges and sizes, thereby increasing the flexibility of use. A fastening threaded hole is provided between the two circular rings for fastening the sensor probes. The fixings 1200 are mounted on the second electric displacement stage 1203, and the distance between the displacement sensor 1201 and the pole plates 1202 can be adjusted through the second electric displacement stage 1203 to ensure that the displacement response of the pole plates 1202 is within the measurable range of the displacement sensor 1201, thereby achieving effective measurement of micro-thrust.

[0065] See also Figures 3 to 7 It needs to be further explained that the Fabry-Perot laser interferometer and the differential system response collector 120 are both used to obtain reference signals and measured signals. Among them, after the reference signal and the measured signal are obtained by the differential system response collector 120, the measured signal and the reference signal are differentially processed to obtain a differential mode signal, which is used to calibrate or adjust the Fabry-Perot laser interferometer and mutually verify the rationality of the micro-thrust measurement results. At the same time, the above-mentioned differential mode signal is used to identify the dynamic property parameters of the micro-thrust measurement device 11, and by judging the difference in the vibration response recorded by the two displacement sensors 1201 of the differential system response collector 120, the various components of the micro-thrust measurement device 11 are adjusted to make the micro-thrust measurement device reach the best working state.

[0066] The present invention obtains a reference signal and a measured signal through a differential system response collector 120, and debugs a Fabry-Perot laser interferometer and identifies system parameters of a micro-thrust measurement device 11 based on the reference signal and the measured signal. When the micro-thrust measurement device reaches an optimal working state, displacement measurement is performed through laser interferometer measurement. With such a setting, the measurement accuracy of the present invention can be greatly improved, thereby enabling high-precision measurement of tiny thrusts.

[0067] See also Figure 3 to Figure 4As a possible implementation, the reference signal output unit 110 and the measured signal output unit 111 are each configured with an electromagnetic force source 121, which is used to identify the dynamic property parameters of the reference signal output unit and the measured signal output unit, respectively. Each electromagnetic force source 121 includes a permanent magnet 1210, which is installed at a position close to the lower end of the reference signal output unit 110 and the measured signal output unit 111 but above the damping plate 1123. The electromagnetic force source also includes a DC coil 1211, which is installed on a third electric translation platform 122 outside the reference signal output unit 110 and the measured signal output unit 111. The DC coil 1211 is coaxially arranged with the permanent magnet 1210, the permanent magnet has a fixed first center point, and the DC coil has a movable second center point, and the position of the second center point relative to the first center point can be accurately adjusted by the mobile platform. The positional relationship between the DC coil 1211 and the permanent magnet 1210 can be adjusted by adjusting the third electric translation stage 122 , so that the electromagnetic force source 121 can provide a high-precision calibration force source for the micro-thrust measurement device 11 .

[0068] Exemplarily, before the electromagnetic force source 121 is installed on the micro-thrust measurement device 11, the weighing method is used to calibrate the optimal relative position relationship between the permanent magnet 1210 and the DC coil 1211 and the DC coil by an electronic analytical balance. Then, according to the driving control equation, a known calibration force is applied to the reference signal output unit and the measured signal output unit, and the dynamic property parameters are obtained by inversion based on the measured system response, and the dynamic property parameters of the reference signal output unit and the measured signal output unit are identified; the micro-thrust measurement device is leveled using a leveling platform. The reference signal output unit and the measured signal output unit are adjusted so that they have consistent dynamic property parameters, that is, they have the same stiffness coefficient, inertia coefficient and damping coefficient.

[0069] In actual application, first, the superconducting magnetic suspension vibration isolation platform is controlled to make the micro-thrust measurement device in a stable suspension state, and the dynamic property parameters of the micro-thrust measurement device are identified under the action of electromagnetic force to achieve the best working state. The specific operation is: the same direct current is passed through the two electromagnetic force sources 121 to realize the known electromagnetic force generated by loading the two T-type plates 118. At this time, the two flexible springs 116 will undergo bending vibration, and the two displacement sensors 1201 will respectively record the vibration response generated by the corresponding T-type plates 118. Since the reference signal output unit 110 and the measured signal output unit 111 hoisted by the two flexible springs 116 have the same structure and system dynamic property parameters, under the same electromagnetic force, the vibration response recorded by the two displacement sensors 1201 is consistent. If there is a large difference in the vibration response recorded by the two displacement sensors 1201, the various components of the micro-thrust measurement device 11 are verified and fine-tuned to make the micro-thrust measurement device reach the best working state. Secondly, direct current is only applied to the electromagnetic force source 121 on the same side as the measured signal output unit 111. At this time, only the flexible spring sheet 116 on this side will undergo bending vibration, while the other side will only be affected by external noise excitation. The relative displacement of the two T-plates 118 is measured by the laser interferometer 119, that is, the vibration response after eliminating the external noise is measured. Under the action of the damper 112, the measured vibration response will gradually tend to a steady-state response. , according to the formula , the stiffness coefficient of the micro-thrust measurement device can be obtained, where is the calibration arm, i.e., the distance from the axis of the electromagnetic force source 121 to the center line of the flexible spring sheet 116, and is the distance between the measuring arm, i.e., the center axis of the laser interferometer 119 and the center line of the flexible spring sheet 116. Finally, the measured signal output unit 111 is started, and the measured thrust is applied. The flexible spring sheet 116 on the side where the measured signal output unit 111 is located undergoes bending vibration under the measured thrust. The relative displacement of the two T-plates 118 is measured by the laser interferometer 119, i.e., the steady-state response of the device under the measured thrust. , and then the average thrust of the measured thrust can be obtained as ,in is the thrust arm to be measured, that is, the distance from the central axis of the thruster nozzle to the center line of the flexible spring sheet 116. For example, the influence of random errors can be reduced by averaging multiple measurements to improve the measurement accuracy of the average thrust.

[0070] In a second aspect, the present invention provides a measurement method. Before executing the measurement method, the reference signal output unit and the measured signal output unit included in the micro-thrust measurement device are identified for dynamic property parameters, that is, first, an electronic balance is used to calibrate the optimal relative position relationship between the permanent magnet and the coil and the driving control equation between the current passing through the coil and the electromagnetic force; then, according to the driving control equation, a known calibration force is applied to the reference signal output unit and the measured signal output unit, and the dynamic property parameters are obtained by inversion based on the measured system response, and the dynamic property parameters of the reference signal output unit and the measured signal output unit are identified; the micro-thrust measurement device is leveled using a leveling platform; the reference signal output unit and the measured signal output unit are adjusted so that the two have consistent dynamic property parameters, that is, they have the same stiffness coefficient, inertia coefficient and damping coefficient; the measurement method comprises the following steps:

[0071] Control the superconducting magnetic suspension vibration isolation platform to keep the suspension workbench where the micro-thrust measurement device is located in a stable suspension state;

[0072] Starting the measured signal output unit to bend the flexible spring sheet of the hoisted measured signal output unit;

[0073] Using a laser interferometer to obtain a differential signal between a reference signal output unit and a measured signal output unit, wherein the differential signal is a system response;

[0074] The micro-thrust is calculated based on the system response, the stiffness coefficient, the distance from the central axis of the thruster nozzle included in the measured signal output unit to the center line of the flexible spring, and the distance from the central axis of the laser interferometer to the center line of the flexible spring.

[0075] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A micro-thrust measurement device, characterized in that: include: Superconducting magnetic levitation vibration isolation platform to isolate environmental noise; and a micro-thrust measurement device carried by a superconducting magnetic levitation vibration isolation platform; The micro-thrust measurement device has a reference signal output unit and a measured signal output unit with consistent structures and dynamic property parameters, so as to output reference signals and measured signals respectively, and the dynamic property parameters at least include stiffness coefficient, inertia coefficient and damping coefficient; an effective micro-thrust signal is obtained based on the measured signal and the reference signal; the reference signal output unit and the measured signal output unit are respectively configured with dampers; the dampers are double eddy current dampers; each double eddy current damper includes a guide rail, a yoke pair carried on the guide rail, a permanent magnet pair arranged on the opposite end faces of the yoke pair, and a damping plate hoisted at the lower end of the reference signal output unit or the measured signal output unit, and the tail of the damping plate is located in the air gap between the permanent magnet pairs; The reference signal output unit and the measured signal output unit are symmetrically arranged and are both suspended by flexible spring sheets; the flexible spring sheets are detachable, and the relationship between the thickness of the flexible spring sheets and the stiffness coefficient and the load-bearing capacity of the micro-thrust measuring device is determined; flexible spring sheets of different thicknesses are replaced according to the stiffness coefficient and the load-bearing capacity required by the micro-thrust measuring device to form a micro-thrust measuring device with multiple gears; The micro-thrust measurement device also includes a laser interferometer and a differential system response collector; wherein the differential system response collector is used to obtain a reference signal and a measured signal output by a reference signal output unit and a measured signal output unit respectively, and further obtain a first differential signal based on the reference signal and the measured signal; the first differential signal is used to calibrate the laser interferometer; the laser interferometer is used to obtain a second differential signal between the reference signal output unit and the measured signal output unit, and further obtain a measurement value of the micro-thrust measurement device based on the second differential signal.

2. The micro-thrust measurement device according to claim 1, characterized in that: The flexible spring piece is made of a material with a hardness greater than or equal to 36HRC, an elastic modulus greater than or equal to 133GPa, a yield limit greater than or equal to 1037MPa, a fatigue limit greater than or equal to 750MPa, a tensile strength greater than or equal to 1106GPa, and a corrosion resistance coefficient less than 0.005mm / a.

3. The micro-thrust measurement device according to claim 1, characterized in that: The thickness of the flexible spring sheet is smaller than the thickness of the component on which it is suspended, and the thickness of the component on which the flexible spring sheet is suspended is larger than the thickness of the flexible spring sheet.

4. The micro-thrust measurement device according to claim 1, characterized in that: The flexible spring is made of beryllium bronze, carbon spring steel, chrome-molybdenum spring steel, silicon-manganese spring steel, vulcanized spring steel, molybdenum spring steel or nickel alloy spring steel.

5. The micro-thrust measurement device according to claim 1, characterized in that: The laser interferometer is a Fabry-Perot laser interferometer.

6. The micro-thrust measurement device according to claim 1, characterized in that: Two flexible springs are hoisted on the diaphragm of the leveling platform included in the micro-thrust measurement device, and the expansion rate of the diaphragm is less than or equal to 10 -7 K -1 .

7. The micro-thrust measurement device according to claim 1, characterized in that: The reference signal output unit and the measured signal output unit are each configured with an electromagnetic force source, which is respectively used to identify the dynamic property parameters of the reference signal output unit and the measured signal output unit; each electromagnetic force source includes a permanent magnet, which is installed at a position close to the lower end of the reference signal output unit and the measured signal output unit but above the damping plate; the electromagnetic force source also includes a DC coil, which is installed on a mobile platform outside the reference signal output unit and the measured signal output unit; the DC coil is coaxially arranged with the permanent magnet, the permanent magnet has a fixed first center point, and the DC coil has a movable second center point, and the position of the second center point relative to the first center point can be accurately adjusted by the mobile platform.

8. A micro-thrust measurement method, characterized in that: Before executing the micro-thrust measurement method, the reference signal output unit and the measured signal output unit included in the micro-thrust measurement device described in claim 7 are identified for dynamic property parameters, that is, first, an electronic balance is used to calibrate the optimal relative position relationship between the permanent magnet and the DC coil and the driving control equation between the current flowing through the DC coil and the electromagnetic force; then, according to the driving control equation, a known calibration force is applied to the reference signal output unit and the measured signal output unit, and the dynamic property parameters are obtained by inversion based on the measured system response, and the dynamic property parameters of the reference signal output unit and the measured signal output unit are identified; the micro-thrust measurement device is leveled using a leveling platform; the reference signal output unit and the measured signal output unit are adjusted so that the two have consistent dynamic property parameters, that is, they have the same stiffness coefficient, inertia coefficient and damping coefficient; the micro-thrust measurement method comprises the following steps: Control the superconducting magnetic suspension vibration isolation platform to keep the suspension workbench where the micro-thrust measurement device is located in a stable suspension state; Starting the measured signal output unit to bend the flexible spring sheet of the hoisted measured signal output unit; Using a laser interferometer to obtain a differential signal between a reference signal output unit and a measured signal output unit, wherein the differential signal is a system response; The micro-thrust is calculated based on the system response, the stiffness coefficient, the distance from the central axis of the thruster nozzle included in the measured signal output unit to the center line of the flexible spring, and the distance from the central axis of the laser interferometer to the center line of the flexible spring.

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