An automatic calibration device and system for micro-thrust frames based on modulated pulse width

Abstract

This invention proposes an automatic calibration device and system for a micro-thrust frame based on modulated pulse width. The device includes: a mounting guide post, a friction rod, two sets of piezoelectric units, and a ball bearing slide. The mounting guide post is located at one end of the friction rod and connected to an external connecting plate structure. A ball bearing slide is nested inside the friction rod, and two sets of piezoelectric units are sequentially arranged axially on the outside. Each set of piezoelectric units includes two piezoelectric units positioned opposite both sides of the friction rod. In response to power-on activation of the piezoelectric units, the piezoelectric units move axially along the friction rod, thereby driving the friction rod to move along the ball bearing slide. The piezoelectric unit movement amplitude of this invention is adjustable, achieving sub-micron level movement. Furthermore, the generated tension is linearly fitted, thereby pre-obtaining a tension fitting curve at the nanonewton level corresponding to the modulated pulse width, achieving precise calibration of the nanonewton level thrust.

Description

Technical Field

[0001] This invention relates to the field of electric thruster technology, and in particular to an automatic calibration device and system for a micro-thruster based on modulated pulse width. Background Technology

[0002] Electric propulsion refers to a power device that uses an electric or magnetic field to accelerate and ionize a working propellant, thereby generating thrust. It has been widely used in various propulsion missions of spacecraft, such as attitude control, orbital position maintenance, orbital maneuvers, and interplanetary flight.

[0003] In the development of electric propulsion engines, precise measurement of the engine's thrust is crucial. However, the thrust of electric propulsion engines is extremely small, ranging from millinewtons to micronewtons, posing significant challenges to accurate measurement. To eliminate systematic errors in the thrust measurement device and improve measurement accuracy, high-precision calibration of the device is necessary to obtain the accurate relationship between the input force and the output signal. Existing calibration methods primarily employ the pulley and weight method. Standard weights generate a known gravitational force, which is then converted into a horizontal tension force via pulleys, thereby calibrating the measurement device.

[0004] However, the pulley and weight method has a drawback when calibrating thrust at the nanonewton level:

[0005] (1) The friction of the pulley, the weight and tension of the suspension line cannot be accurately predicted, resulting in an unknown correspondence between the actual calibration force, i.e. the standard force used for calibration and the value indicated by the weight;

[0006] (2) In order to achieve accurate calibration of the thrust measuring device under different ranges, a large number of weights with different mass combinations are required, which is quite cumbersome.

[0007] (3) The weight of the suspension line and the tray makes it impossible to calibrate with forces smaller than these, which affects the calibration of the thrust measuring device in a smaller thrust range;

[0008] (4) Because different weights need to be changed, this method is very cumbersome when calibrating the vacuum environment. It requires constant closing and vacuuming of the vacuum chamber and gas replenishment and opening of the chamber.

[0009] (5) When manually loading weights, the shaking and swaying caused by manual operation will affect the calibration accuracy and require a long time to reach stillness, resulting in a long calibration time each time. Summary of the Invention

[0010] The technical problem to be solved by the present invention is how to achieve accurate calibration of thrust at the nanonewton level; in view of this, the present invention provides an automatic calibration device and system for micro-thrust frames based on modulation pulse width.

[0011] The technical solution adopted in this invention is an automatic calibration device for a micro-thrust frame based on modulation pulse width, comprising: a mounting guide column, a friction rod, two sets of piezoelectric units, and a ball bearing slide bar;

[0012] The mounting guide post is located at one end of the friction rod and is connected to the external connecting plate structure.

[0013] The friction rod has a ball bearing slide nested inside it, and two sets of piezoelectric units are arranged sequentially along the axial direction on the outside. Each set of piezoelectric units includes two piezoelectric units arranged opposite to the two sides of the friction rod. In response to the power-on start of the piezoelectric units, the piezoelectric units move along the axial direction of the friction rod, thereby driving the friction rod to move along the ball bearing slide.

[0014] In one embodiment, the two sets of piezoelectric units are arranged perpendicular to each other.

[0015] In one embodiment, the piezoelectric unit includes: a base, a piezoelectric element, and a friction rod contact body;

[0016] The base is fixed to one end of the piezoelectric body, and the other end of the piezoelectric body is connected to the friction rod contact body;

[0017] The piezoelectric body has positive and negative electrodes connected to its inner and outer surfaces, respectively. In response to the potential change after being energized, the piezoelectric body moves along the axial direction of the friction rod.

[0018] In one embodiment, the apparatus further includes:

[0019] A first support frame is used to support one group of the piezoelectric units;

[0020] The second support frame is used to support another set of the piezoelectric units;

[0021] A ball bearing slide mounting base is used to fix the ball bearing slide.

[0022] In one embodiment, the friction rod is made of a metal material that is not easily deformed, and the outer friction layer is made of a non-metallic material with a rough surface and wear resistance.

[0023] In one embodiment, the mounting guide post is connected to an external connecting plate structure via a clearance fit.

[0024] In one embodiment, of the two sets of piezoelectric units, the set of piezoelectric units closer to the mounting guide post is arranged parallel to the ground, and the other set of piezoelectric units is arranged perpendicular to the ground.

[0025] Another aspect of the present invention provides an automatic calibration system for a micro-thrust frame based on modulated pulse width, comprising: an automatic calibration device for a micro-thrust frame based on modulated pulse width as described in any of the preceding claims, an electric propulsion mounting base, a connecting plate, a torsion pendulum, a counterweight, a displacement sensor, a damper, and a calibration controller;

[0026] The torsion pendulum is provided with an electric propulsion mounting base and a connecting plate at one end, and the connecting plate is connected to the automatic calibration device; the torsion pendulum is provided with a counterweight, a displacement sensor and a damper at one end.

[0027] In response to the pulse current control of the calibration controller, the automatic calibration device generates motion so that the automatic calibration system obtains an external constant force.

[0028] Using the above technical solution, the piezoelectric unit of the present invention has an adjustable motion amplitude, which can achieve submicron level motion. Furthermore, the generated tension is linearly fitted, thereby obtaining the tension fitting curve at the nanonewton level corresponding to the modulation pulse width in advance, and realizing the accurate calibration of the nanonewton level thrust. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the automatic calibration system for a micro-thrust frame based on modulation pulse width according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the automatic calibration device for a micro-thrust frame based on modulation pulse width according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the friction rod and ball slide assembly according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the piezoelectric unit structure according to an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of the control logic of the piezoelectric unit according to an embodiment of the present invention.

[0034] Figure Labels

[0035] 1-Vacuum chamber, 2-Electric propulsion mounting base, 3-Automatic calibration device, 4-Connecting plate, 5-Torsion pendulum, 6-Counterweight, 7-Displacement sensor, 8-Damper, 9-Automatic calibration controller, 10-Pass-through flange, 11-Sensor controller, 12-Data processing front end;

[0036] 13-Installation guide post, 14-Friction rod, 15-Piezoelectric unit, 16-First support frame, 17-Support frame, 18-Ball slide rod mounting seat, 19-Ball slide rod;

[0037] 151-Base, 152-Piezoelectric element, 153-Friction rod contact body. Detailed Implementation

[0038] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0039] In the accompanying drawings, the thickness, size, and shape of the objects have been slightly exaggerated for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale.

[0040] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed feature, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0041] As used herein, the terms “basically,” “approximately,” and similar terms are used as terms of approximation rather than terms of degree, and are intended to describe inherent biases in measured or calculated values ​​that will be recognized by those skilled in the art.

[0042] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] To facilitate understanding of the contents of this invention, the relevant concepts involved in this invention will be introduced below:

[0045] Piezoelectric effect: When certain dielectrics are deformed by an external force along a certain direction, polarization occurs within them, resulting in opposite charges appearing on their two opposing surfaces. When the external force is removed, they return to their uncharged state; this phenomenon is called the direct piezoelectric effect. When the direction of the force changes, the polarity of the charges also changes. Conversely, when an electric field is applied along the polarization direction of the dielectric, it deforms; when the electric field is removed, the deformation disappears; this phenomenon is called the inverse piezoelectric effect.

[0046] Piezoelectric motor: An electric motor that uses the inverse piezoelectric effect of piezoelectric element 152 to convert electromechanical energy.

[0047] The first embodiment of the present invention provides an automatic calibration system for a micro-thrust frame based on modulated pulse width, such as... Figure 1 As shown, it may include: a vacuum chamber 1, an electric propulsion mounting base 2, an automatic calibration device 3, a connecting plate 4, a torsion pendulum 5, a counterweight 6, a displacement sensor 7, a damper 8, an automatic calibration controller 9, a through-chamber flange 10, a sensor controller 11, and a data processing front end 12.

[0048] The main improvement of this invention based on the prior art lies in the automatic calibration device 3, the connecting plate 4, and the automatic calibration controller 9, which, together with other components of the system, complete the micro-thrust measurement of electric propulsion and the automatic calibration function before thrust measurement.

[0049] Specifically, the main function of the automatic calibration device 3 is, under the control of the automatic calibration controller 9, to apply the modulation pulse width to the corresponding electrode of the piezoelectric ceramic based on the modulation pulse width and piezoelectric effect. The inverse piezoelectric effect converts electrical energy into mechanical energy, which is then converted into a tension force on the calibration rod through friction. By adjusting parameters such as the frequency and amplitude of the modulation pulse width, a linear tension force is generated until the constant force required for calibration is achieved. This achieves the purpose of automatic calibration.

[0050] In a second embodiment of the present invention, an automatic calibration device 3 for a micro-thrust frame based on modulation pulse width is described, with reference to... Figure 2 It includes: mounting guide post 13, friction rod 14, two sets of piezoelectric units 15, and ball slide rod 19;

[0051] Among them, the guide post 13 is set at one end of the friction rod 14 and is structurally connected to the external connecting plate 4;

[0052] In this embodiment, the friction rod 14 is internally nested with the ball slide rod 19, and two sets of piezoelectric units 15 are arranged sequentially along the axial direction on the outside. Each set of piezoelectric units 15 includes two piezoelectric units 15 arranged opposite to the two sides of the friction rod 14. In response to the power-on start of the piezoelectric units 15, the piezoelectric units 15 move along the axial direction of the friction rod 14, thereby driving the friction rod 14 to move along the ball slide rod 19.

[0053] Furthermore, the two sets of piezoelectric units 15 are arranged perpendicular to each other. Optionally, of the two sets of piezoelectric units 15, the set of piezoelectric units 15 closer to the mounting guide post 13 is arranged parallel to the ground, and the other set of piezoelectric units 15 is arranged perpendicular to the ground.

[0054] Furthermore, the device may also include: a first support frame 16 for supporting one group of the piezoelectric units 15; a second support frame 17 for supporting another group of the piezoelectric units 15; and a ball bearing slide 19 mounting base 18 for fixing the ball bearing slide 19.

[0055] Preferably, the friction rod 14 is made of a metal material that is not easily deformed, and the outer friction layer is made of a non-metallic material with a rough surface and wear resistance.

[0056] For example, the mounting guide post 13 can be connected to the external connecting plate 4 structure via a clearance fit.

[0057] In this embodiment, the mounting guide post 13 is fitted to the connecting plate 4 with a clearance fit. The connecting plate 4 is directly mounted on the torsion 5 of the micro-thrust frame through two mounting holes. The connecting plate 4 has a through hole with a guide chamfer. After cleaning the through hole and the mounting guide post 13 with anhydrous ethanol or quick-drying cleaner, the mounting guide post 13 can be directly inserted into the through hole with a clearance fit, thereby realizing the quick installation and combination of the automatic calibration device 3 and the micro-thrust frame of the present invention.

[0058] In this embodiment, the friction rod 14, in conjunction with four (two sets) piezoelectric units 15 and ball bearing slides 19, achieves micro-movement of the friction rod 14, and the assembly is as follows: Figure 3 As shown. Specifically, the hollow rod inside the friction rod 14 is made of a metal material with excellent comprehensive mechanical properties and is not easily deformed, while the outer friction layer is made of a non-metallic material with a rough surface and wear resistance. The ball bearing slide 19 is fitted inside the friction rod 14 to minimize resistance during the micro-movement of the friction rod 14 and to support the friction rod 14.

[0059] In this embodiment, the piezoelectric unit 15 is mainly made using the inverse piezoelectric effect principle, such as... Figure 4 As shown, it specifically includes: a base 151, a piezoelectric body 152, and a friction rod 14 contact body 153; wherein, the base 151 is fixed to one end of the piezoelectric body 152, and the other end of the piezoelectric body 152 is connected to the friction rod contact body 153; the inner and outer surfaces of the piezoelectric body 152 are respectively connected to positive and negative electrodes, and in response to the potential change after being energized, the piezoelectric body 152 moves along the axial direction of the friction rod 14.

[0060] In other words, the base 151 serves to fix one end of the piezoelectric element 152. The piezoelectric element 152 is an actuator operating under the inverse piezoelectric effect, with positive and negative electrodes connected to its internal and external surfaces, respectively. When energized, due to the change in potential, the piezoelectric element 152 will generate micro-movements in the horizontal direction shown in the figure. The amplitude of this movement is adjustable according to the modulation pulse width of the power supply, achieving sub-micron level movement. Since its left side is fixed by the base 151, the mechanical movement generated by the piezoelectric element 152 can only be horizontally to the right, thereby driving the friction rod contact body 153 to move horizontally. Under the control of the specific modulation pulse width output by the automatic calibration controller 9, the piezoelectric unit 15 can generate regular horizontal rightward vibrations as shown in the figure.

[0061] The calibration process of this embodiment will be explained below based on an application example. Figure 5 As shown.

[0062] Can be referenced again Figure 2 For ease of explanation, the four piezoelectric units are divided into two groups of 15. Figure 2 The group shown on the left is called piezoelectric unit assembly 1, which will... Figure 2 The group shown on the right is called piezoelectric unit combination 2.

[0063] The first pulse: The modulation pulse width of piezoelectric unit assembly 1 corresponds to a high level. At this time, the piezoelectric element 152 of piezoelectric unit 15 generates the inverse piezoelectric effect due to the potential difference, and the friction rod contact body 153 moves. The control of piezoelectric unit assembly 1 is synchronous and without delay. Therefore, the movement direction of piezoelectric unit assembly 1 at the time of the first pulse is shown in the figure. The friction rod contact bodies 153 of the two piezoelectric units 15 simultaneously apply frictional force to the friction rod 14. The two forces with an included angle... Figure 5 A component force is generated in the vertically downward direction, causing the friction rod 14 to make a slight downward movement.

[0064] The second pulse: The modulation pulse width of piezoelectric unit assembly 1 corresponds to a low level, and piezoelectric body 152 returns to its original length. At this time, the friction rod contact body 153 of piezoelectric unit 15 is not in contact with friction rod 14, therefore... Figure 5 When the downward force component generated by the pulse disappears, the friction rod 14 returns to its initial state due to the presence of the damper 8. However, at this time, the modulation pulse width of the piezoelectric unit assembly 2 corresponds to a high level. Similarly, the relative pressure generated by the piezoelectric unit assembly 2 is converted into frictional force, fixing the friction rod 14 in this position.

[0065] The third pulse: The modulation pulse width of piezoelectric unit combination 1 corresponds to a high level, and the modulation pulse width of piezoelectric unit combination 2 corresponds to a low level. Similarly, it can be deduced that piezoelectric unit combination 2 returns to a low level state, the pressure on the fixed friction rod 14 disappears, and the two forces with an included angle... Figure 5A component force is generated in the vertically downward direction, causing the friction rod 14 to continue to make a slight downward motion.

[0066] The cycle continues as described above until the predetermined number of pulses for calibration control is completed. At this point, the micro-thrust frame receives an external constant force, thus achieving the traditional method of calibration using weights and pulleys.

[0067] This invention proposes using linear tensile force, pre-fitting a curve, and controlling the output of a predetermined modulation pulse width to achieve a desired constant force. The invention's own measurement and calibration method involves using a micro-tension force (micro-Newton or millinewyn level) sensor to linearly fit the tensile force generated by the invention. This allows for the pre-obtaining of the tensile force fitting curve corresponding to the modulation pulse width, which is beneficial for automatically calibrating the accuracy of the data.

[0068] In summary, compared with the prior art, the present invention has at least the following advantages:

[0069] 1) The piezoelectric unit of the present invention has an adjustable motion amplitude, and can achieve submicron level motion. Its own measurement and calibration method is to use a micro-tension sensor (micro-Newton level or millinewton level) to linearly fit the tension generated by the present invention, thereby obtaining the tension fitting curve corresponding to the modulation pulse width in advance, showing the accurate calibration of the nano-micronewton level thrust.

[0070] 2) The embodiments of the present invention can replace the existing pulley and weight combination, avoiding the inability of the pulley and weight combination to effectively evaluate the magnitude of the friction force generated by the pulley, thereby affecting the calibration effectiveness;

[0071] 3) Achieve accurate calibration of the thrust measuring device in different ranges without using combinations of weights of different masses;

[0072] 4) Increase the thrust calibration range required for the thrust measurement device;

[0073] 5) It eliminates the need for repeated opening and closing of the cabin, enabling real-time calibration of the thrust measurement device and improving calibration efficiency;

[0074] 6) Calibration can be completed automatically without manual operation.

[0075] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A modulation pulse width-based micro-thrust frame automatic calibration device, characterized in that, Comprise: The installation guide column, friction rod, two groups of piezoelectric units, ball slide rod; Wherein, the installation guide column is provided at one end of the friction rod, and is connected with the external connecting plate structure; The inside of the friction rod is nested with the ball slide rod, and the outside is sequentially provided with two groups of piezoelectric units along the axial direction, each group of piezoelectric units includes two piezoelectric units arranged on both sides of the friction rod; in response to the power-on starting of the piezoelectric unit, the piezoelectric unit generates movement along the axial direction of the friction rod, thereby driving the friction rod to generate movement along the ball slide rod.

2. The modulated pulse width based micro-thrust stand automatic calibration device according to claim 1, wherein, Two groups of piezoelectric units are arranged in perpendicular directions.

3. The modulated pulse width based micro-thruster rack automatic calibration device of claim 2, wherein, The piezoelectric unit comprises: base, piezoelectric body, friction rod contact body; Wherein, the base is fixed at one end of the piezoelectric body, and the other end of the piezoelectric body is connected with the friction rod contact body; The inside and the outer surface of the piezoelectric body are respectively connected with positive and negative electrodes, and in response to the potential change after power-on, the piezoelectric body generates movement along the axial direction of the friction rod.

4. The modulated pulse width based micro-thruster rack automatic calibration device of claim 3, wherein, The device further comprises: The first support frame is used to support one group of piezoelectric units; The second support frame is used to support the other group of piezoelectric units; The ball slide rod mounting seat is used to fix the ball slide rod.

5. The modulated pulse width based micro-thrust stand automatic calibration device according to claim 1, wherein, The friction rod is made of a metal material that is not easy to deform, and the outer friction layer is made of a non-metal material with rough surface and wear resistance.

6. The modulated pulse width based micro-thrust stand automatic calibration device according to claim 1, wherein, The installation guide column is gap fitted to the external connecting plate structure.

7. The modulated pulse width based micro-thrust stand automatic calibration device according to claim 2, wherein, Among the two groups of piezoelectric units, one group of piezoelectric units close to the installation guide column is arranged parallel to the ground, and the other group of piezoelectric units is arranged perpendicular to the ground.

8. A micro-thrust stand automatic calibration system based on modulated pulse width, characterized in that, Comprise: The modulation pulse width-based micro-thrust frame automatic calibration device, electric propulsion mounting seat, connecting plate, torsional pendulum, counterweight, displacement sensor, damper, calibration controller in any one of claims 1 to 7; Wherein, the torsional pendulum is provided with an electric propulsion mounting seat and a connecting plate at one end, and the connecting plate is connected with the automatic calibration device; the other end of the torsional pendulum is provided with a counterweight, a displacement sensor and a damper; In response to the pulse current control of the calibration controller, the automatic calibration device generates movement, so that the automatic calibration system obtains an external constant force.

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