CN217424317U - Air floating platform - Google Patents
Air floating platform Download PDFInfo
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- CN217424317U CN217424317U CN202221231156.7U CN202221231156U CN217424317U CN 217424317 U CN217424317 U CN 217424317U CN 202221231156 U CN202221231156 U CN 202221231156U CN 217424317 U CN217424317 U CN 217424317U
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Abstract
The application discloses an air bearing table. The air floating platform comprises a load disc, an air floating bearing assembly, a grating assembly and a small angle measuring assembly; the air-bearing assembly comprises an air-bearing shaft and a bearing seat, the air-bearing shaft is connected with the load disk, and an air film can be formed between the air-bearing shaft and the bearing seat so as to generate the gravity which counteracts the load disk through the air film to enable the load disk to float and rotate freely around the air-bearing shaft; the grating assembly is connected with the air floating shaft and used for measuring the angular position of the air floating platform; the small-angle measuring assembly comprises a photoelectron collimator and a mirror body, one of the photoelectron collimator and the mirror body is fixed on the load disc, the other one of the photoelectron collimator and the mirror body is static relative to the bearing seat, and the optical axis of the photoelectron collimator is aligned with the mirror surface of the mirror body. The air bearing table can improve the angular position measurement accuracy of 360-degree full rotation and micro displacement of the load disc through the cooperation of the grating assembly and the small-angle measurement assembly.
Description
Technical Field
The application relates to the technical field of test equipment, in particular to an air bearing table.
Background
At present, the air bearing table can be used for a spacecraft attitude control full-physical simulation test, and the requirement of the spacecraft attitude control full-physical simulation test on the angular position precision of the air bearing table is relatively high. But the existing air bearing table cannot ensure the angular position testing precision.
SUMMERY OF THE UTILITY MODEL
The application provides an air bearing table at least to improve air bearing table's angular position test accuracy.
A first aspect of the application provides an air bearing table comprising a load tray, an air bearing assembly, a grating assembly and a small angle measurement assembly;
the air-bearing assembly comprises an air-bearing shaft and a bearing seat, the air-bearing shaft is connected with the load disk, and an air film can be formed between the air-bearing shaft and the bearing seat so as to generate the gravity which counteracts the load disk through the air film to enable the load disk to float and rotate freely around the air-bearing shaft;
the grating assembly is connected with the air floating shaft and used for measuring the angular position of the air floating platform;
the small-angle measuring assembly comprises a photoelectron collimator and a mirror body, one of the photoelectron collimator and the mirror body is fixed on the load disc, the other one of the photoelectron collimator and the mirror body is static relative to the bearing seat, and the optical axis of the photoelectron collimator is aligned with the mirror surface of the mirror body.
The photoelectron collimator is fixed on the load disc, the mirror body is a plane mirror, and the mirror body is static relative to the bearing seat.
The grating assembly comprises a grating and a reading head, the grating is connected with one end, far away from the load disc, of the air floating shaft, and the reading head is connected with the bearing seat and opposite to the grating in position.
Wherein, at least two reading heads are uniformly arranged on the circumference of the grating.
Wherein, the air floating platform also comprises an air floating platform body;
the air floating platform body is connected with the bearing seat, and is provided with an air inlet channel communicated with an air flow channel between the bearing seat and the bearing so as to form an air film between the bearing seat and the bearing when the air inlet channel of the air floating platform body is ventilated.
Wherein, the two ends of the surface of the air floating platform body far away from the load disc are symmetrically provided with sizing blocks.
Wherein, one end of the air floating platform body, which is far away from the surface of the load disc, is provided with at least two plane sizing blocks, and a hoisting device for adjusting the inclination angle of the air floating platform body is arranged between the at least two plane sizing blocks;
the other end of the air floating platform body, which is far away from the surface of the load disk, is provided with an adjusting sizing block.
Wherein, the air supporting platform still includes the balancing weight, and the balancing weight sets up in the outside of air supporting platform body.
The air floating platform further comprises a truss, the truss is sleeved on the outer side of the air floating platform body and connected with the load disc, and the balancing weight is installed on the outer side of the truss.
The air floating platform further comprises a battery, and the battery is electrically connected with the reading head and the photoelectron collimator.
The beneficial effect of this application is: the application provides an air bearing table, this air bearing table has grating subassembly and small-angle measurement subassembly, so this application air bearing table can adopt grating subassembly and small-angle measurement subassembly to measure air bearing table's angular position in coordination, and specifically accessible grating subassembly carries out the angular position measurement of big angle (as 360) to air bearing table angular position when carrying out little displacement (as 360 ") through the small-angle measurement subassembly measures, so can improve the angular position measurement accuracy of 360 full gyrations of load dish and little displacement through grating subassembly and small-angle measurement subassembly cooperation. And this application air supporting platform simple structure, convenient operation and measurement accuracy are higher.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.
FIG. 1 is a schematic diagram of a gas floating platform according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural view of a gas bearing assembly in a gas table according to an embodiment of the present application;
fig. 3 is a schematic measurement diagram of a small angle measurement assembly according to an embodiment of the present disclosure.
FIG. 4 is a schematic view of the arrangement of the grating and the reading head in the grating assembly according to one embodiment of the present disclosure;
FIG. 5 is a schematic flow chart illustrating a method for detecting an error in an angular position of a gas floating platform according to an embodiment of the present disclosure;
FIG. 6 is a schematic flow chart illustrating a method for detecting an error in an angular position of a gas floating platform according to another embodiment of the present disclosure;
fig. 7 is a schematic diagram illustrating placement of mirrors in a method for detecting an error in an angular position of a gas floating stage according to another embodiment of the present disclosure.
In the figures, the reference numbers are: 100 is an air floating platform; 1 is a load disk; 2 is an air floating shaft; 3 is a bearing seat; 4 is an upper floating plate; 5 is a fastener protecting cover; 6 is a grating; 7 is a reading head; 8 is a grating seat; 9 is a connecting boss; 10 is a reading head seat; 11 is a photoelectric autocollimator; 12 is a lens body; 13 is a lens bracket; 14 is an air floating stage body; 15 is a bottom plate; 16 is a plane sizing block; 17 is hoisting equipment; 18 is an adjusting sizing block; 19 is a balancing weight; 20 is a battery; 21 is a battery mounting seat; 22 is a truss; 23 is a fixed rod; and 24 is a protective cover.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the above description of the present specification, the terms "fixed," "mounted," "connected," or "connected," and the like, are to be construed broadly unless otherwise expressly specified or limited. For example, with the term "coupled", it can be fixed, removable, or integral; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship. Therefore, unless the specification explicitly defines otherwise, those skilled in the art can understand the specific meaning of the above terms in the present application according to specific circumstances.
From the above description of the present specification, those skilled in the art will also understand the terms used below, terms indicating orientation or positional relationship such as "upper", "lower", "front", "rear", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", "central", "longitudinal", "transverse", "clockwise" or "counterclockwise" and the like are based on the orientation or positional relationship shown in the drawings of the present specification, it is used for convenience in explanation of the disclosure and for simplicity in description, and does not explicitly show or imply that the devices or elements involved must be in the particular orientation described, constructed and operated, therefore, the above terms of orientation or positional relationship should not be interpreted or construed as limiting the present application.
In addition, the terms "first" or "second", etc. used in this specification are used to refer to numbers or ordinal terms for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present specification, "a plurality" means at least two, for example, two, three or more, and the like, unless specifically defined otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
As shown in fig. 1, the present application proposes an air bearing table 100, the air bearing table 100 comprising a load tray 1, an air bearing assembly, a grating assembly and a small angle measurement assembly.
Wherein, as shown in fig. 2, the air bearing assembly comprises an air bearing shaft 2 and a bearing housing 3. The air-bearing shaft 2 is connected with the load disc 1, an air film can be formed between the air-bearing shaft 2 and the bearing seat 3, the gravity for offsetting the load disc 1 is generated through the air film, the load disc 1 floats and freely rotates around the air-bearing shaft 2, friction-free motion of the air-bearing shaft 2 is achieved, the purpose of free rotation of a certain shaft of a simulated satellite in orbit operation is achieved through full physical simulation, and the high-precision and high-stability attitude control effect of the spacecraft can be analyzed and verified through the air-bearing platform 100.
Optionally, the air bearing platform 100 may further include an upper floating plate 4, and the air bearing shaft 2 may be connected to the load tray 1 through the upper floating plate 4. Specifically, one end of the load disk 1 facing the air floating shaft 2 is provided with a groove, and the floating plate 4 is embedded into the groove to be fixedly connected with the load disk 1. In addition, the floating plate 4 can be fixedly connected with the air floating shaft 2 through fasteners such as screws or bolts. And a fastener protecting cover 5 can be arranged above the fasteners of the upper floating plate 4.
Optionally, a grating assembly is connected to the air bearing shaft 2 to measure the rotation angle of the load disk 1 through the grating assembly. Wherein the grating assembly is an angular position measuring assembly that enables large angular movements of the load plate 1. For example, the measurement range of the grating assembly may be 360 °. In addition, the grating assembly accuracy directly affects the angular position measurement accuracy of the air bearing table 100, so that it is preferable that a 26-bit ± 1.3 ″ grating assembly be selected as an angle measurement element to improve the angular position measurement accuracy of the air bearing table 100.
In one implementation, the grating assembly may include a grating 6 and a readhead 7; the grating 6 is connected to the load disk 1 to rotate synchronously with the load disk 1, so that the angular position of the air bearing table 100 can be measured by the angular position of the grating 6; when the grating assembly is in an operating state, the position of the reading head 7 is relatively static, and the reading head 7 is opposite to the position of the grating 6, so that the angular position of the grating 6 can be read by the reading head 7, and the angular position of the grating 6 read by the reading head 7 can be used as the angular position of the air bearing table 100.
Specifically, the grating 6 can be connected to the end of the air bearing shaft 2 away from the load disk 1 through the grating seat 8, so that the grating 6 can be disposed on the load disk 1 through the grating seat 8 and the air bearing shaft 2 and rotate synchronously with the load disk 1. One end of the air bearing shaft 2, which is far away from the load disc 1, can also be provided with a connecting boss 9 for mounting the optical grating 6, so that the optical grating 6 can be arranged on the connecting boss 9 through the optical grating seat 8, and the optical grating 6 can be stably mounted on the air bearing shaft 2. In addition, the grating 6 of the present application may be an absolute type circular grating 6. Furthermore, the readhead 7 may be connected to the bearing housing 3 and/or the bearing housing 3 by a readhead mount 10. And as shown in fig. 3, at least two reading heads 7 can be uniformly arranged on the circumference of the grating 6, so that the rotation error of the load disk 1 and second and fourth harmonic errors can be reduced by arranging a plurality of reading heads 7, and the angular position detection accuracy of the air bearing table 100 can be improved. In other implementations, the grating 6 may also be circumferentially arranged with only one read head.
Optionally, after the grating assembly is deployed into the air bearing table 100, or before the grating assembly is used to measure the angular position of the air bearing table 100, it may be verified whether the grating assembly is able to work properly, to ensure that the angular position of the air bearing table 100 can be read by the grating assembly when the air bearing table 100 is in a working state. Specifically, the step of verifying whether the grating assembly can work normally may be: electrifying the reading head 7 to rotate the load disk 1 for one circle; if the reading head 7 is normally on in a green light way in the whole process, the installation positions of the reading head 7 and the grating 6 are suitable, and the grating component can normally work.
Optionally, the small angle measurement assembly comprises an electro-optic autocollimator 11 and a mirror body 12. Wherein one of the photoelectric autocollimator 11 and the mirror body 12 is fixed on the load plate 1. When the air bearing table 100 is in a working state, the other one of the photoelectric autocollimator 11 and the mirror body 12 is static relative to the bearing seat 3, and the optical axis of the photoelectric autocollimator 11 is aligned with the mirror surface of the mirror body 12, so that small-angle accurate measurement of the load disk 1 can be realized through the cooperation of the photoelectric autocollimator 11 and the mirror body 12, for example, ultra-high-precision angular position measurement with angular position accuracy of 0-0.5 "in a measurement range of 0-360 ″.
In one implementation, as shown in fig. 1, the photoelectric autocollimator 11 is fixed to the load tray 1, and the mirror body 12 is stationary with respect to the bearing housing 3; for example, the mirror body 12 can be fixedly placed on the ground or on a table surface near the load disk 1 by means of the mirror body mount 13, so that the angular position measurement during small displacements of the load disk 1 can be realized by means of the mirror body 12 in cooperation with the photoelectric autocollimator 11 fixed on the load disk 1. And the photoelectric autocollimator 11 can be arranged in any area of the load disk 1, for example in the center of rotation of the load disk 1 or in the peripheral area of the load disk 1. And the setting position of the photoelectric autocollimator 11 has no influence on the measurement accuracy of the small-angle measurement assembly, for example, as shown in fig. 4, when the photoelectric autocollimator 11 is respectively installed in two cases of passing through the rotation center and not passing through the rotation center, and the load disk 1 is rotated by 10 °, the turntable angle measured by the photoelectric autocollimator 11 is 10 ° in both cases. Preferably, the photoelectric autocollimator 11 is connected to the peripheral region of the load plate 1, so that the central region and/or the remaining peripheral region of the load plate 1 are used for placing leveling blocks and testing instruments such as loads.
In addition, both the photoelectric autocollimator 11 and the mirror body 12 can be horizontally placed, so that the optical axis of the photoelectric autocollimator 11 can be aligned with the mirror surface of the mirror body 12 after the angles of the photoelectric autocollimator 11 and the mirror body 12 are adjusted. Wherein the mirror body 12 may be a flat mirror or other mirror body 12.
Before the angular position of the air bearing table 100 is measured by using the small-angle measuring component, the positions of the mirror body 12 and/or the photoelectric autocollimator 11 can be adjusted in a state that the load disk 1 is static, so that the emitted laser of the photoelectric autocollimator 11 can vertically enter the mirror surface of the mirror body 12, that is, the vertical and horizontal directions of the mirror surface of the mirror body 12 are perpendicular to the direction of the emitted laser of the photoelectric autocollimator 11, so as to ensure that the photoelectric autocollimator 11 finds an image; then, the numerical value of the photoelectric autocollimator 11 can be cleared; after the above steps are completed, the small-angle measurement component may be used to measure the small displacement of the load board 1, and specifically, if the load board 1 is rotated within the working range of the photoelectric autocollimator 11, the reading of the photoelectric autocollimator 11 may be used as the rotation angle of the load board 1.
Optionally, the air bearing table 100 may further include an air bearing table body 14, and the air bearing table body 14 may be connected to the bearing housing 3.
The air floating platform 14 may further have an air inlet channel communicated with the air flow channel between the bearing seat 3 and the air floating shaft 2, so that an air film is formed between the bearing seat 3 and the air floating shaft 2 when the air inlet channel of the air floating platform 14 is ventilated.
In addition, the end of the air floating platform body 14 of the air floating platform 100 far away from the load disk 1 can be provided with a bottom plate 15 which is convenient to detach so as to check the operation conditions of the grating 6 and the reading head 7 at any time.
In addition, two ends of the air floating platform body 14 far away from the surface of the load disk 1 may be symmetrically provided with sizing blocks, so as to stably support the air floating platform body 14 and the bearing seat 3 and other components arranged thereon.
Specifically, one end of the air floating platform body 14 away from the surface of the load tray 1 may be provided with at least two planar sizing blocks 16, so as to support the air floating platform body 14 and the bearing seat 3 and other components arranged thereon securely by the at least two planar sizing blocks 16 and the sizing block arranged at the other end of the air floating platform body 14 away from the surface of the load tray 1. The surface of the planar sizing block 16 close to the air floating stage body 14 may be a plane.
A lifting device 17 for adjusting the inclination angle of the air floating platform body 14 may be disposed between the at least two plane sizing blocks 16, so that one end of the air floating platform body 14 may be lifted by the lifting device 17 to incline the air floating platform body 14, and the inclination angle of the air floating platform body 14 may be adjusted by the lifting device 17. In particular, the lifting device 17 may be a jack, for example a split double-section hydraulic jack.
In addition, the other end of the air floating platform 14 away from the surface of the load tray 1 may be provided with an adjusting sizing block 18, such that the adjusting sizing block 18 is disposed opposite to the plane sizing block 16, so as to support the other end of the air floating platform 14 by the adjusting sizing block 18 when the lifting device 17 tilts the air floating platform 14.
Optionally, the air floating platform 100 may further include a weight 19, so that when the air floating platform 100 tilts to generate an unbalanced moment, the unbalanced moment is compensated by the weight 19 to balance the air floating platform 100. The weight 19 may be disposed outside the air floating stage 14. And the weight 19 can be connected to the load tray 1 to rotate synchronously with the load tray 1.
The air bearing stage 100 may further include a battery 20, and the battery 20 may be disposed outside the air bearing stage body 14. And the battery 20 may be connected to the load tray 1 to rotate in synchronism with the load tray 1. Specifically, the battery 20 may be attached to the load tray 1 by a battery mount 21.
The battery 20 may be electrically connected to the reading head 7 and the photoelectric autocollimator 11, so as to supply power to the reading head 7, the photoelectric autocollimator 11 and/or other power consuming components through the battery 20. The battery 20 may also provide power to load the load of the tray 1. The battery 20 may be a lead-acid battery 20, a lithium battery 20, or the like. For example, the battery 20 may be an 8 string 100Ah lead acid battery 20.
Further, the air bearing stage body 14 may also include a truss 22. The truss 22 may be sleeved outside the air bearing stage body 14, so as to place the counterweight 19 and/or the battery 20 and other components through the truss 22 disposed outside the air bearing stage body 14. The truss 22 may be attached to the load tray 1 such that the clump weight 19 and the battery 20 may be attached to the load tray 1 via the truss 22 to provide a moment of inertia for the load tray 1. In particular, the clump weight 19 and/or the battery 20 may be mounted on the outside of the truss 22. Further, the clump weight 19 and/or the battery mount 21 are mounted to the truss 22 by fasteners (e.g., bolts or fixing rods 23).
In addition, a protective cover 24 may be provided on the load tray 1. Illustratively, a protective cover 24 is provided over the center of rotation of the load tray 1.
In the present embodiment, the present application provides an air bearing table 100, the air bearing table 100 has a grating component and a small-angle measurement component, so the air bearing table 100 of the present application can adopt the grating component and the small-angle measurement component to cooperatively measure the angular position of the air bearing table 100, specifically, the angular position measurement of a large angle (e.g. 360 °) can be performed through the grating component, and the angular position measurement of the air bearing table 100 when a small displacement (e.g. 360 ") is performed through the small-angle measurement component, so the angular position measurement accuracy of the full rotation and the small displacement of the air bearing table 100 can be improved through the cooperation of the grating component and the small-angle measurement component. The air bearing table 100 is simple in structure, convenient to operate and high in measurement accuracy. The application also provides an embodiment air bearing table angular position error detection method. As shown in fig. 5, the air bearing table angular position error detection method of this embodiment may include the following steps.
S101: and adjusting the position of the mirror body and/or the photoelectric autocollimator so that the optical axis of the photoelectric autocollimator is aligned with the mirror surface of the mirror body, and recording the current reading alpha of the grating assembly and the current reading beta of the photoelectric autocollimator.
The position of the mirror body and/or the photoelectric autocollimator can be adjusted firstly until the optical axis of the photoelectric autocollimator is aligned with the mirror surface of the mirror body, and the current reading alpha of the grating component and the current reading beta of the photoelectric autocollimator can be recorded after the adjustment is finished, so that the load disk can be rotated in the measurement range of the photoelectric autocollimator side subsequently, and the reading alpha of the rotated grating component can be obtained i And reading beta of photoelectric autocollimator i And using the formula error ═ max [ (alpha) 1 -α)-(β 1 -β)，…，(α i -α)-(β i -β)]And calculating the angular position error of the air bearing table, so that the angular position error of the grating assembly can be determined by using the small-angle measuring assembly with higher measuring precision.
Preferably, in step S101, the adjustment of the position of the mirror and/or the position of the photoelectric autocollimator may be stopped when the optical axis of the photoelectric autocollimator is perpendicular to the mirror surface of the mirror, so as to determine the measurement range of the photoelectric autocollimator and to determine the angular position error of the grating assembly at the mirror position by using the method of the present application.
In addition, after the position of the mirror body and/or the photoelectric autocollimator is adjusted, the reading of the photoelectric autocollimator can be cleared, so that the current reading beta of the photoelectric autocollimator is 0.
S102: rotating the load disk at least once within the measuring range of the photoelectric autocollimator and recording the reading alpha of the grating assembly after each rotation i And reading beta of photoelectric autocollimator i 。
After step S101, the load tray may be rotated by an angle, and the measurement range of the photoelectric autocollimator is not exceeded, and the readings of the rotated grating assembly and the photoelectric autocollimator are recorded respectively; then repeatedly executing the steps of rotating the load disk by an angle and ensuring that the measurement range of the photoelectric autocollimator is not exceeded, and respectively recording the readings of the grating assembly and the photoelectric autocollimator after rotation, thus obtaining the reading alpha of the grating assembly after each rotation i And reading beta of photoelectric autocollimator i Wherein i is the number of rotations.
The load disk is rotated in the measuring range of the photoelectric autocollimator, and the rotated grating reading and the photoelectric autocollimator reading are recorded, so that the measuring precision of the photoelectric autocollimator can be ensured, and the angular position error of the grating assembly can be accurately calculated by using the reading of the photoelectric autocollimator.
S103: with the formula error ═ max [ (alpha) 1 -α)-(β 1 -β)，…，(α i -α)-(β i -β)]The angular position error of the air bearing table is calculated.
After step S103 is completed, the position of the mirror body may be moved, and then step S101, step S102 and step S103 are sequentially performed to obtain an angular position error of the air bearing table at the new mirror body position; by repeating the above steps, the angular position errors of the air bearing table at a plurality of mirror positions can be obtained.
In addition, the air bearing tables at a plurality of mirror positions can be used after the angular position errors of the air bearing tables at a plurality of mirror positions are obtained based on the stepsAngular position error estimates the angular position error for the full travel of the air bearing table. Can be specifically formulated as error General assembly ＝max(error 1 ，error 2 ，…，error j ) Calculating the angular position error of the full stroke of the air bearing table General assembly 。
Illustratively, the measurement data table shown in table 1 can be obtained by the above-described air bearing table angular position error detection method. As can be seen from table 1, the angular position error of the air bearing table is 2.1 ° at mirror position 1 (i.e., the grating position corresponding to the load disk is about 120.4263 °), 0.6 ° at mirror position 2 (i.e., the grating position corresponding to the load disk is about 187.0218 °), 1.4 ° at mirror position 3 (i.e., the grating position corresponding to the load disk is about 234.1597 °), and 0.37 ° at mirror position 4 (i.e., the grating position corresponding to the load disk is about 299.2801 °). And by the formula error General assembly ＝max(error 1 ，error 2 ，…，error j ) The angular position error of the full stroke of the air bearing table can be determined General assembly Was found to be 2.1 ".
TABLE 1 measurement data Table
Further, as shown in fig. 6, the present application may also provide another embodiment air bearing table angular position error detection method. As shown in fig. 6, the air bearing table angular position error detection method of this embodiment may include the following steps.
S201: the angular position errors of the air bearing table at the j mirror positions are determined.
The angular positions of the air bearing tables at the j mirror positions can be sequentially determined, so that an error fitting function of the angular positions of the air bearing tables is obtained by utilizing a harmonic compensation method based on the angular position errors of the j mirror positions; and then, the reading of the grating assembly is reversely compensated by the error fitting function, so that the error of the angular position of the grating assembly at each position can be determined based on the error fitting function determined by the error of the angular position of the air floating table at the j mirror positions, and then the reading of the grating assembly is reversely compensated by the error of the angular position at each position, so that the reading precision of the grating assembly after reverse compensation is higher, the error is smaller, and a more accurate angular position can be obtained by the method.
In step S201, the above steps S101, S102 and S103 may be performed in sequence to obtain an angular position error of the air bearing table at the first mirror position; then the load disk is rotated to enable the photoelectric autocollimator on the load disk to be opposite to the mirror body at the second mirror body position, and then the steps S101, S102 and S103 are sequentially executed to obtain the angular position error of the air bearing table at the second mirror body position; by repeating the above steps, the angular position errors of the air floating table at j lens positions can be obtained. Namely, the positions of the mirror body and/or the photoelectronic collimator are adjusted in sequence, the load disk is rotated at least once in the measuring range of the photoelectronic autocollimator, and the reading alpha of the grating assembly after each rotation is recorded respectively i And reading beta of photoelectric autocollimator i And the formula error is max [ (alpha) 1 -α)-(β 1 -β)，…，(α i -α)-(β i -β)]Calculating the angular position error of the air floating platform to obtain the angular position error of the air floating platform at different positions of the mirror body x Wherein x is the serial number of the position of the mirror body, and x is 1 to j.
As shown in fig. 7, the j mirror positions may be evenly distributed around the periphery of the load tray, thus facilitating determination of an accurate error fit function by evenly distributing the j mirror positions. j may be set according to actual conditions, and is not limited herein, and may be, for example, 6 or 8.
In one implementation, the j mirrors may be uniformly arranged around the periphery of the load tray. When determining the angular position errors of the air bearing table at j mirror positions, assigning 1-j to x in sequence, and when x is updated, sequentially executing the steps of rotating the load disk to enable the photoelectric autocollimator on the load disk to be opposite to the mirror at the x-th mirror position, S101, S102 and S103.
In another implementation, the j mirror locations are evenly distributed around the periphery of the load tray. When determining the angular position errors of the air bearing table at j mirror positions, repeatedly and sequentially moving the mirror to the x-th mirror position, rotating the load disk to enable the photoelectric autocollimator on the load disk to be opposite to the mirror at the x-th mirror position, and sequentially performing the steps S101, S102 and S103, wherein x is 1-j, so that the angular position errors of the air bearing table at j mirror positions uniformly distributed on the periphery of the load disk can be obtained through the steps.
S202: and obtaining an error fitting function of the angular position of the air bearing table by utilizing a harmonic compensation method based on the angular position errors of the j mirror positions.
After determining the angular position errors of the j mirror positions, an error fitting function of the angular positions of the air bearing table can be obtained by utilizing a harmonic compensation method.
Wherein the formula of the error fitting function may be:
wherein, a k And b k Harmonic coefficients of the error fitting function, a k And b k The calculation formulas of (a) and (b) are respectively as follows:
where alpha is the matrix coefficient.
In step S202, the angular position error of the air bearing table at j mirror positions is used to calculate a based on the above formula k And b k (ii) a Then using the calculated a k And b k Determining an error fitting function so as to determine the reading error of the grating assembly at different angular positions of the air bearing table based on the error fitting function subsequently, thus the reading of the grating assembly at the corresponding angular positions can be subsequently determinedThe error carries out reverse compensation on the reading of the grating assembly of the load disc, and the accurate air-bearing table angle position can be obtained through the reading of the grating assembly and an error fitting function, so that the detection accuracy of the air-bearing table angle position is improved.
Alternatively, the matrix expression of the matrix coefficients may be: alpha (y) ═ 2.0 π/j; wherein y is 1 to j.
M may be set according to actual conditions (e.g., detection accuracy requirement), and is not limited herein. Illustratively, m may be 6 or 7.
S203: the readings of the grating assembly are inversely compensated with an error fitting function.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.
Claims (10)
1. An air bearing table, comprising:
a load tray;
the air bearing assembly comprises an air bearing shaft and a bearing seat, the air bearing shaft is connected with the load disk, and an air film can be formed between the air bearing shaft and the bearing seat, so that the air film can generate the gravity which counteracts the load disk to enable the load disk to float and rotate freely around the air bearing shaft;
a grating assembly coupled to the air bearing shaft for measuring an angular position of the air bearing table;
the small angle measurement assembly comprises a photoelectron collimator and a mirror body, one of the photoelectron collimator and the mirror body is fixed on the load disc, the other one of the photoelectron collimator and the mirror body is static relative to the bearing seat, and the optical axis of the photoelectron collimator is aligned with the mirror surface of the mirror body.
2. The air bearing table of claim 1 wherein the optoelectronics collimator is fixed to the load plate, the mirror is a flat mirror, and the mirror is stationary relative to the bearing mount.
3. The air bearing table of claim 1, wherein the grating assembly comprises a grating attached to an end of the air bearing shaft remote from the load plate and a read head attached to the bearing housing opposite the grating.
4. The air bearing table of claim 3, wherein the grating is circumferentially uniformly arranged with at least two of the read heads.
5. The air bearing table of claim 1, further comprising an air bearing table body;
the air floating platform body is connected with the bearing seat, and is provided with an air inlet channel communicated with an air flow channel between the bearing seat and the bearing, so that the air film is formed between the bearing seat and the bearing when the air inlet channel of the air floating platform body is ventilated.
6. The air bearing table of claim 5, wherein two ends of the air bearing table body away from the surface of the load tray are symmetrically provided with sizing blocks.
7. The air bearing table of claim 6, wherein at least two planar sizing blocks are disposed at an end of the air bearing table body away from the surface of the load tray, and a lifting device for adjusting the inclination angle of the air bearing table body is disposed between the at least two planar sizing blocks;
and the other end of the air floating platform body, which is far away from the surface of the load disc, is provided with an adjusting sizing block.
8. The air bearing table of claim 6, further comprising a weight disposed outside the air bearing table body.
9. The air bearing table of claim 8, further comprising a truss frame, wherein the truss frame is sleeved outside the air bearing table body and connected with the load plate, and the counterweight is installed outside the truss frame.
10. The air bearing table of claim 1, further comprising a battery electrically connected to the grating assembly and the optoelectronic collimator.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221231156.7U CN217424317U (en) | 2022-05-20 | 2022-05-20 | Air floating platform |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221231156.7U CN217424317U (en) | 2022-05-20 | 2022-05-20 | Air floating platform |
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| CN217424317U true CN217424317U (en) | 2022-09-13 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115793500A (en) * | 2023-02-06 | 2023-03-14 | 湖南揽月机电科技有限公司 | Small-sized single-shaft air bearing table semi-physical simulation system and working method |
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2022
- 2022-05-20 CN CN202221231156.7U patent/CN217424317U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115793500A (en) * | 2023-02-06 | 2023-03-14 | 湖南揽月机电科技有限公司 | Small-sized single-shaft air bearing table semi-physical simulation system and working method |
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