Air-floating friction coefficient measurement and error analysis system and method based on active feedback

Abstract

The invention relates to a system and method for measuring and error analyzing air-floating friction coefficient based on active feedback, and belongs to the field of space technology. The invention proposes an active feedback air-floating friction coefficient measurement method, which can accurately measure the startup and steady-state friction coefficients of a spacecraft in an air-suspended state, thereby obtaining the air-floating friction interference term in the dynamic control model, making the dynamic model more accurate and improving the effectiveness of ground verification tests of spacecraft.

Description

Technical Field

[0001] The present invention relates to an air-floating friction coefficient measurement and error analysis method based on active feedback, which belongs to the field of ground demonstration and verification tests and weak parameter measurement methods, and can be used in tasks such as the design of ground test systems, friction estimation of air-floating zero-gravity equipment, and precise modeling of dynamic models. Background Art

[0002] The functions and performance requirements of spacecraft launch missions are constantly moving towards complexity, diversification and precision. Complex functions and high and precise index requirements have put forward special requirements for the design of spacecraft and high-fidelity verification on the ground. The air suspension method has the characteristics of high precision, low cost and unlimited test time. It is an important and widespread solution for spacecraft to achieve micro-low gravity characteristics in the ground gravity field environment. It is of great significance for the functional demonstration and control algorithm verification of spacecraft. Due to the viscous characteristics of compressed gas, the air suspension method inevitably has a certain friction resistance, which brings error terms to the dynamic control model of the spacecraft, affecting the accuracy of the dynamic model and even the effectiveness of the control algorithm. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide an air-floating friction coefficient measurement and error analysis method based on active feedback, to accurately measure the startup and steady-state friction coefficients of a spacecraft in an air-floating state, thereby obtaining the air-floating friction interference term in a dynamic control model, making the dynamic model more accurate, and improving the effectiveness of ground verification tests of spacecraft.

[0004] The technical solution of the present invention is: an air-floating friction coefficient measurement and error analysis system based on active feedback, including a drive motor, a reducer, a flexible push rod, a pressure sensor, a ball joint contact plate, a load, a flexible air supply pipeline, a data processing unit, a posture adjustment mechanism, an air cushion, and an air-floating platform;

[0005] The output shaft of the driving motor is connected to the input end of the reducer to achieve the output of driving force and speed adjustment;

[0006] The flexible push rod is connected to the output end of the reducer; the rear end of the pressure sensor is fixedly connected to the flexible push rod, and the front end is fixedly connected to the ball joint contact plate; the flexible push rod, the pressure sensor and the ball joint contact plate jointly realize the measurement of the incremental thrust and driving force curve of the load; the ball joint contact plate adapts to the unstructured shape of the load to ensure the stability of the thrust output;

[0007] The flexible air supply pipeline provides compressed gas to the air cushion to achieve gravity compensation of the load on the air floating platform, so that the load is in a free floating state relative to the air floating platform;

[0008] The data processing unit is used for processing the force measurement data of the pressure sensor and visualizing the thrust curve;

[0009] The posture adjustment mechanism and the air cushion are adjusted respectively so that the flexible push rod and the load are both in a horizontal state relative to the air floating platform.

[0010] Furthermore, the driving motor cooperates with the reducer to adjust the thrust application speed by adjusting the rotation speed of the motor, and ensure the repeatability of force application, thereby improving the accuracy of friction force measurement.

[0011] Furthermore, a flexible link is provided inside the flexible push rod to prevent the ball joint contact plate from impacting the load at the moment of contact, thereby causing distortion of the measurement result of the pressure sensor. The flexible link is also used to extend the contact time and obtain force-time data, thereby improving the accuracy of the measurement result.

[0012] Furthermore, the ball joint contact plate adapts to assembly errors and posture deviations through a universal ball joint device, thereby ensuring that the front end plane of the ball joint contact plate is always in contact with the load during the thrust application process.

[0013] Furthermore, the data processing unit is used to monitor the measurement data of the pressure sensor online, and judge whether the adjustment accuracy of the measuring device meets the requirements and whether the repeatability of multiple friction force measurements meets the preset requirements through fitting of the data curve.

[0014] Furthermore, the posture adjustment mechanism is in the form of distributed multi-point support, and the height and pitch angle of the measuring device can be adjusted simultaneously by adjusting the height of each part, so that the thrust application position of the measuring device meets the preset requirements and remains level with the air floating platform;

[0015] Furthermore, the air cushion is used in multiple groups to achieve the distribution of load weight, so that a uniform air film is formed between the air cushion and the air floating platform; at the same time, the same height and pitch angle adjustment function as the posture adjustment mechanism is achieved, so that the load and the air floating platform remain level.

[0016] Furthermore, the flexible air supply pipeline realizes air supply for multiple groups of air cushions through a centralized-distributed air supply method, and at the same time adopts a spiral winding method to reduce the interference force of the flexible air supply pipeline in the extension direction and the friction between the flexible air supply pipeline and the air flotation platform, thereby improving the measurement accuracy of the air flotation friction.

[0017] Furthermore, the measuring device and the object to be measured are both on the same air-floating platform, and the relative position deviation between the two is reduced by improving the flatness of the air-floating platform, thereby improving the measurement accuracy.

[0018] The air-floating friction coefficient measurement and error analysis method implemented by the air-floating friction coefficient measurement and error analysis system based on active feedback includes:

[0019] The posture adjustment mechanism and the air cushion are adjusted respectively so that the measuring device and the load are in a horizontal state relative to the air-floating platform. Then, the driving motor is set to run at a constant speed. The driving motor pushes out the flexible push rod at a certain lateral speed through the reducer. The flexible push rod, together with the torque sensor 4 and the ball joint contact plate, moves at a constant speed until it comes into contact with the outer side of the load. At this time, the torque sensor gradually increases from 0. Through the visualization processing of the data processing unit, a thrust-time curve is formed. The load begins to overcome the air-floating friction resistance and accelerates until the thrust of the flexible push rod is the same as the air-floating friction resistance. The load speed increases to the maximum. At this time, the thrust-time curve reaches the peak value, and the peak thrust F max Record, repeat the above process, and record the peak thrust F of multiple sets of thrust-time curves max , take the average value as the measured value of air flotation friction resistance F + , complete the air-floating friction coefficient measurement and error analysis.

[0020] The advantages of the present invention compared with the prior art are:

[0021] (1) The device of the present invention can realize real-time visualization of the measured value of air-floating friction resistance, and directly output the measured value of air-floating friction coefficient through the data processing unit, effectively improving the measurement efficiency;

[0022] (2) The device of the present invention introduces a flexible link to extend the application time of the driving thrust, collects as much thrust data as possible, avoids large measurement errors caused by rigid collision, and improves the measurement accuracy of the air-floating friction coefficient;

[0023] (3) The measuring device and the load of the present invention can be kept relatively level with the air-floating platform through the posture adjustment device. Multiple measurements of thrust reversal can also greatly reduce the error introduced by the horizontality of the air-floating platform, further improving the measurement accuracy of the air-floating friction coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the composition of the air-floating friction coefficient measuring device of the present invention;

[0025] Figure 2 This is a thrust measurement curve diagram of the pressure sensor of the present invention. DETAILED DESCRIPTION

[0026] In order to better understand the above technical scheme, the technical scheme of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0027] The following is a further detailed description of the air-floating friction coefficient measurement and error analysis method based on active feedback provided by the embodiment of the present application in conjunction with the accompanying drawings. The specific implementation method may include (eg Figures 1-2 As shown): drive motor, reducer, flexible push rod, pressure sensor, ball joint contact plate, load, flexible air supply pipeline, data processing unit, posture adjustment mechanism, air cushion, air floating platform and other parts, which are used to obtain the friction resistance during the startup and operation of the air suspension system, so as to calculate its air floating friction coefficient, with the advantages of high precision, adaptive unstructured targets, easy implementation and strong repeatability.

[0028] Specifically, the output shaft of the driving motor 1 is connected to the input end of the reducer 2 to realize the output of the driving force and speed regulation; the flexible push rod 3 is connected to the output end of the reducer 2; the rear end of the pressure sensor 4 is fixedly connected to the flexible push rod 3, and the front end is fixedly connected to the ball joint contact plate 5; the flexible push rod 3, the pressure sensor 4 and the ball joint contact plate 5 jointly realize the measurement of the increasing thrust and driving force curve of the load 6; the ball joint contact plate 5 adapts to the unstructured shape of the load 6 to ensure the stability of the thrust output; the flexible air supply pipeline 7 provides compressed gas to the air cushion 10 to realize the gravity compensation of the load 6 on the air floating platform 11, so that the load 6 is in a free floating state relative to the air floating platform 11; the data processing unit 8 is used for the force measurement data processing of the pressure sensor 4 and the visualization of the thrust curve; the posture adjustment mechanism 9 and the air cushion 10 are adjusted respectively so that the flexible push rod 3 and the load 6 are in a horizontal state relative to the air floating platform 11.

[0029] Furthermore, the driving motor 1 cooperates with the reducer 2 to adjust the thrust application speed by adjusting the rotation speed of the motor, and ensure the repeatability of force application, thereby improving the accuracy of friction force measurement.

[0030] In one possible implementation, a flexible link is provided inside the flexible push rod 3 to prevent the ball joint contact plate 5 and the load 6 from generating impact at the moment of contact, thereby causing distortion of the measurement result of the pressure sensor 4. The flexible link is also used to extend the contact time and obtain force-time data, thereby improving the accuracy of the measurement result.

[0031] Furthermore, in a possible implementation, the ball joint contact plate 5 adapts to assembly errors and posture deviations through a universal ball joint device to ensure that the front end plane of the ball joint contact plate 5 is always in contact with the load 6 during the thrust application process.

[0032] In one possible implementation, the data processing unit 8 is used to monitor the measurement data of the pressure sensor 4 online, and judge whether the adjustment accuracy of the measuring device meets the requirements and whether the repeatability of multiple friction force measurements meets the preset requirements through fitting of the data curve.

[0033] In a possible implementation, the posture adjustment mechanism 9 is in the form of distributed multi-point support, and the height and pitch angle of the measuring device are adjusted simultaneously by adjusting the height of each part, so that the thrust application position of the measuring device meets the preset requirements and remains level with the air floating platform 11;

[0034] Optionally, in one possible implementation, the air cushion 10 is used in multiple groups to achieve the distribution of the weight of the load 6, so that a uniform air film is formed between the air cushion 10 and the air floating platform 11; at the same time, the same height and pitch angle adjustment function as the posture adjustment mechanism 9 is achieved, so that the load 6 and the air floating platform 11 remain level.

[0035] Furthermore, the flexible air supply pipeline 7 realizes air supply for multiple groups of air cushions 10 through a centralized-distributed air supply method, and at the same time adopts a spiral winding method to reduce the interference force of the flexible air supply pipeline 7 in the extension direction and the friction between the flexible air supply pipeline 7 and the air floating platform 11, thereby improving the measurement accuracy of the air floating friction force.

[0036] In a possible implementation, the measuring device and the object to be measured are both on the same air-floating platform 11 , and the relative position deviation between the two is reduced by improving the flatness of the air-floating platform 11 , thereby improving the measurement accuracy.

[0037] Based on Figure 1 With the same inventive concept, the present invention also provides an air-floating friction coefficient measurement and error analysis method implemented by an air-floating friction coefficient measurement and error analysis system based on active feedback, comprising the following steps:

[0038] The posture adjustment mechanism 9 and the air cushion 10 are adjusted respectively so that the measuring device and the load 6 are in a horizontal state relative to the air floating platform 11. Then, the driving motor 1 is set to run at a constant speed. The driving motor 1 passes through the reducer 2 and pushes out the flexible push rod 3 at a certain lateral speed. The flexible push rod 3, together with the torque sensor 4 and the ball joint contact plate 5, moves at a constant speed until it comes into contact with the outer side of the load 6. At this time, the torque sensor gradually increases from 0. Through the visualization processing of the data processing unit 8, a thrust-time curve is formed. The load 6 begins to overcome the air floating friction resistance and accelerates until the thrust of the flexible push rod is the same as the air floating friction resistance. The speed of the load 6 increases to the maximum. At this time, the thrust-time curve reaches the peak value, and the peak thrust F max Record, repeat the above process, and record the peak thrust F of multiple sets of thrust-time curvesmax , take the average value as the measured value of air flotation friction resistance F + , complete the air-floating friction coefficient measurement and error analysis.

[0039] In the solution provided in the embodiment of the present application, the measuring device is mainly composed of a drive motor 1, a reducer 2, a flexible push rod 3, a pressure sensor 4, a ball joint contact plate 5, a load 6, a flexible air supply pipeline 7, a data processing unit 8, a posture adjustment mechanism 9, an air cushion 10, an air floating platform 11 and the like.

[0040] The air-floating friction coefficient measuring device can be divided into modules such as driving, measuring, and data processing according to functions. The output shaft of the driving motor 1 is connected to the input end of the reducer 2 to realize the output of the driving force and speed regulation. The flexible push rod 3 is connected to the output end of the reducer 2. The rear end of the pressure sensor 4 is fixedly connected to the flexible push rod 3, and the front end is fixedly connected to the ball joint contact plate 5. The flexible push rod 3, the pressure sensor 4, and the ball joint contact plate 5 jointly realize the measurement of the increasing thrust and driving force curve of the load 6. If the flexible push rod 3 is replaced with a rigid rod, a rigid collision will occur between the ball joint contact plate 5 and the load 6, resulting in a large contact collision force, causing the pressure sensor 4 to measure the data with a peak value, and the curve amplitude changes greatly, and the measurement error of the thrust curve also increases accordingly, which will eventually cause the air-floating friction coefficient measurement result to deviate excessively from the true value; the data processing unit 8 realizes the force measurement data processing of the pressure sensor 4 and the visualization of the thrust curve, and the ball joint contact plate 5 can adapt to the unstructured shape of the load 6 to ensure the stability of the thrust output. The flexible air supply pipeline 7 provides compressed gas to the air cushion 10 (the air cushion 10 is usually used in combination) to achieve gravity compensation of the load 6 on the air floating platform 11, so that the load 6 is in a free floating state relative to the air floating platform 11. Under ideal conditions, the load is only affected by the air floating friction resistance during movement.

[0041] Based on Figure 1 With the same inventive concept, the present application also provides an air-floating friction coefficient measurement and error analysis method implemented by an air-floating friction coefficient measurement and error analysis system based on active feedback, comprising the following steps:

[0042] The position adjustment mechanism 9 and the air cushion 10 are adjusted respectively so that the measuring device and the load are in a horizontal state relative to the air floating platform 11. Then the driving motor 1 is set to run at a constant speed. The driving motor 1 passes through the reducer 2 and pushes out the flexible push rod 3 at a certain lateral speed. The flexible push rod 3, together with the torque sensor 4 and the ball joint contact plate 5, moves at a constant speed until it comes into contact with the outer side of the load 6. At this time, the torque sensor gradually increases from 0. Through the visualization processing of the data processing unit 8, a Figure 2In the thrust (F / N)-time (t / s) curve, load 6 begins to overcome the air bearing friction resistance and accelerates due to the thrust. When the thrust of the flexible push rod is equal to the air bearing friction resistance, the speed of load 6 increases to the maximum. At this time, the thrust-time curve reaches the peak value, and the peak thrust F max Record, repeat the above process, and record the peak thrust F of multiple sets of thrust-time curves max , take the average value as the measured value of air flotation friction resistance F + .

[0043] Since the thrust of the measuring device is not horizontal and there are errors between the air-floating platform 11 and the ground level, the measuring device is moved to the other side of the load, and the above measurement work is repeated several times, and the peak thrust F of multiple sets of thrust-time curves are also recorded. max , take the average value as the measured value of the air flotation friction resistance in this direction F - , which can effectively reduce the measurement error of air-floating friction resistance and improve the measurement accuracy of air-floating friction coefficient.

[0044] Air bearing friction resistance in two directions F + And F-take the average, you can get the measured value of the air-floating friction force. Assuming the load mass is M and the air-floating friction coefficient is μ, then:

[0045]

[0046] The above calculation process and curve visualization can be automatically realized by the data measurement unit 8, and the air-floating friction coefficient μ can be directly output, which can effectively improve the measurement efficiency.

[0047] In summary, based on the extensive needs of the above-mentioned engineering tasks, this patent proposes an active feedback air-floating friction coefficient measurement method, which can accurately measure the startup and steady-state friction coefficients of a spacecraft in an air-suspended state, thereby obtaining the air-floating friction interference term in the dynamic control model, making the dynamic model more accurate and improving the effectiveness of ground verification tests of spacecraft.

[0048] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0049] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. The air-floating friction coefficient measurement and error analysis system based on active feedback is characterized by: It comprises a driving motor (1), a reducer (2), a flexible push rod (3), a pressure sensor (4), a ball joint contact plate (5), a load (6), a flexible air supply pipeline (7), a data processing unit (8), a posture adjustment mechanism (9), an air cushion (10), and an air floating platform (11); The output shaft of the driving motor (1) is connected to the input end of the reducer (2) to achieve output of driving force and speed regulation; The flexible push rod (3) is connected to the output end of the reducer (2); the rear end of the pressure sensor (4) is fixedly connected to the flexible push rod (3), and the front end is fixedly connected to the ball joint contact plate (5); the flexible push rod (3), the pressure sensor (4) and the ball joint contact plate (5) jointly realize the measurement of the incremental thrust and driving force curve of the load (6); the ball joint contact plate (5) adapts to the unstructured shape of the load (6) to ensure the stability of the thrust output; The flexible air supply pipeline (7) provides compressed gas to the air cushion (10) to achieve gravity compensation of the load (6) on the air floating platform (11), so that the load (6) is in a free floating state relative to the air floating platform (11); The data processing unit (8) is used for processing force measurement data of the pressure sensor (4) and visualizing thrust curves; The posture adjustment mechanism (9) and the air cushion (10) are adjusted respectively so that the flexible push rod (3) and the load (6) are both in a horizontal state relative to the air floating platform (11); The posture adjustment mechanism (9) is in the form of a distributed multi-point support, and the height and pitch angle of the measuring device are adjusted simultaneously by adjusting the height of each part, so that the thrust application position of the measuring device meets the preset requirements and remains level with the air floating platform (11); The air cushion (10) is used in a combined manner in multiple groups to achieve distribution of the weight of the load (6), so that a uniform air film is formed between the air cushion (10) and the air floating platform (11); at the same time, the same height and pitch angle adjustment function as the posture adjustment mechanism (9) is achieved, so that the load (6) and the air floating platform (11) remain level; The measuring device and the object to be measured are both located on the same air-floating platform (11), and the relative position deviation between the two is reduced by improving the flatness of the air-floating platform (11), thereby improving the measurement accuracy.

2. The air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: The driving motor (1) cooperates with the reducer (2) to adjust the thrust application speed by adjusting the rotation speed of the motor, thereby ensuring the repeatability of force application and improving the accuracy of friction force measurement.

3. The air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: The flexible push rod (3) is provided with a flexible link inside to prevent the ball joint contact plate (5) and the load (6) from generating an impact at the moment of contact, thereby causing distortion of the measurement result of the pressure sensor (4). The flexible link is also used to extend the contact time and obtain force-time data, thereby improving the accuracy of the measurement result.

4. The air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: The ball joint contact plate (5) adapts to assembly errors and position deviations through a universal ball joint device, thereby ensuring that the front end plane of the ball joint contact plate (5) is always in contact with the load (6) during the thrust application process.

5. The air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: The data processing unit (8) is used to monitor the measurement data of the pressure sensor (4) online, and to judge whether the adjustment accuracy of the measuring device meets the requirements and whether the repeatability of multiple friction force measurements meets the preset requirements through the fitting of the data curve.

6. The air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: The flexible air supply pipeline (7) realizes air supply to multiple groups of air cushions (10) by means of centralized-distributed air supply, and adopts a spiral winding method to reduce the interference force of the flexible air supply pipeline (7) in the extension direction and the friction between the flexible air supply pipeline (7) and the air floating platform (11), thereby improving the measurement accuracy of the air floating friction force.

7. The air-floating friction coefficient measurement and error analysis method implemented by the air-floating friction coefficient measurement and error analysis system based on active feedback according to claim 1 is characterized in that: include: The posture adjustment mechanism (9) and the air cushion (10) are adjusted respectively so that the measuring device and the load (6) are in a horizontal state relative to the air-floating platform (11). Then, the driving motor (1) is set to run at a constant speed. The driving motor (1) passes through the reducer (2) and pushes out the flexible push rod (3) at a certain lateral speed. The flexible push rod (3) together with the pressure sensor (4) and the ball joint contact plate (5) move at a constant speed until they come into contact with the outer side of the load (6). At this time, the torque sensor gradually increases from 0. Through the visualization processing of the data processing unit (8), a thrust-time curve is formed. The load (6) begins to overcome the air-floating friction resistance and accelerates until the thrust of the flexible push rod is the same as the air-floating friction resistance. The speed of the load (6) increases to the maximum. At this time, the thrust-time curve reaches a peak value, and the peak thrust F max Record, repeat the above process, and record the peak thrust F of multiple sets of thrust-time curves max , take the average value as the measured value of air flotation friction resistance F + , complete the air-floating friction coefficient measurement and error analysis.

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