Air-floating workpiece table with active and passive damping functions

Abstract

The invention relates to an air floatation workpiece table with active and passive damping functions, and belongs to the technical field of ultra-precision motion control. Comprising an air floatation base, an air floatation sliding plate, a micro-motion sliding plate, a voice coil motor, a linear damper, a perpetual motion feedback system and a micro-motion feedback system. An air film gap exists between the air floatation sliding plate and the air floatation base, and the air floatation sliding plate slides along the air floatation base; the micro-motion sliding plate is mounted on the air floatation base; the voice coil motors are installed at the two ends of the micro-motion sliding plate. One end of the linear damper is installed at the end of the micro-motion sliding plate, and the other end of the linear damper is installed on the air floating base and used for passive vibration reduction. The perpetual motion feedback system is mounted on the air floatation base and is used for reading and feeding back the displacement of the air floatation sliding plate; the micro-motion feedback system converts feedback of the perpetual motion feedback system into a vibration suppression instruction to drive the voice coil motor to move for active vibration reduction. The technical problem that the material deformation precision is reduced due to the fact that the vibration reduction stroke is increased and the heating value is increased due to the large load mass of the voice coil motor is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-precision motion control, and particularly relates to a pneumatic workpiece stage with active and passive shock absorption functions. Background Art

[0002] At present, due to the characteristics of high motion accuracy and clean and pollution-free of the pneumatic motion platform, the pneumatic motion platform is widely used in the wafer inspection process. In the existing pneumatic motion platform, pneumatic guide rails are often used to achieve smooth movement without friction and vibration.

[0003] The pneumatic motion platform needs to be used in cooperation with a high-precision marble workbench. During the movement of the motion stage, due to the relationship of action and reaction forces, the movement of the pneumatic platform will cause vibration of the marble workbench (especially in the occasions with large moment of inertia, large acceleration and deceleration, and high dynamic response). Due to the vibration of the marble workpiece table, the dynamic and static performance of the system is reduced. In a set of equipment, the motion platform usually needs to cooperate with other systems (such as optical detection systems, optical processing systems, etc.) to work.

[0004] Generally, in the application occasions of ultra-precision motion control, in order to reduce the vibration of the system, it is necessary to configure a relatively expensive active vibration isolation table to achieve the vibration reduction effect.

[0005] The patent with the publication number of CN116146654A discloses a vibration reduction platform, a workpiece stage with a vibration reduction platform and a vibration reduction platform control method, including a lower bottom plate, an upper top plate, a plurality of air bearings, a sensor assembly and a plurality of voice coil motors; the upper top plate supports the load; the air bearings are arranged between the lower bottom plate and the upper top plate to floatingly support the upper top plate; the sensor assembly is arranged between the lower bottom plate and the upper top plate, and the sensor assembly detects the speed value or displacement value of the lower bottom plate and / or the upper top plate; the voice coil motors are arranged between the lower bottom plate and the upper top plate, the voice coil motors are communicatively connected to the sensor assembly, and the mover end of the voice coil motor can apply a force or a torque to the upper top plate to keep the upper top plate stationary.

[0006] In the use process of the prior art, there are at least the following problems:

[0007] By driving and damping the top plate and the entire load platform through a plurality of voice coil motors, in high-load conditions, the damping stroke of the voice coil motor is too large, and the required control system is more complex. Summary of the Invention

[0008] The present invention provides a pneumatic workpiece stage with active and passive shock absorption functions, which is used to solve the technical problem in the prior art that due to the large load mass of the voice coil motor, the damping stroke required by the voice coil motor during damping will become larger, thereby increasing the heat generation, and thus reducing the material deformation accuracy.

[0009] To achieve the above object, the present invention is implemented through the following technical solutions:

[0010] An air-bearing workpiece stage with both active and passive damping functions, comprising: an air-bearing base, an air-bearing slide, a micro-slide, a voice coil motor, a linear damper, a constant motion feedback system, and a micro-motion feedback system. There is an air film gap between the air-bearing slide and the air-bearing base, and the air-bearing slide slides along the air-bearing base; the micro-slide is installed on the air-bearing base; the voice coil motors are installed at both ends of the micro-slide; one end of the linear damper is installed at the end of the micro-slide, and the other end is installed on the air-bearing base, and the linear dampers are distributed at both ends of the micro-slide for passive vibration damping; the constant motion feedback system is installed on the air-bearing base for reading and feedbacking the displacement of the air-bearing slide; the micro-motion feedback system converts the feedback of the constant motion feedback system into an anti-vibration command to drive the motion of the voice coil motor for active vibration damping.

[0011] Further, the constant motion feedback system includes: a grating scale support, a reading head support, a first reading head, and a first grating scale. The grating scale support is fixed on the air-bearing base; the reading head support is connected to the air-bearing slide; the first reading head is connected to the air-bearing slide through the reading head support; the first grating scale is fixed on the air-bearing base through the grating scale support. When the air-bearing slide slides, it drives the reading head to move, and the first reading head reads the scale lines of the first grating scale to form the displacement feedback of the air-bearing slide.

[0012] Further, the micro-motion feedback system includes: a second reading head, a second grating scale, and a controller. The second reading head is fixedly installed on the air-bearing base; the second grating scale is installed on the micro-slide, and the second reading head reads the displacement of the second grating scale to feedback the displacement of the micro-slide; the controller outputs the feedback information of the second grating scale to the controller, providing data support for the controller to achieve vibration prediction and output anti-vibration commands, and the controller is used to drive the voice coil motor.

[0013] Further, it further includes: a constant motion linear motor and a linear guide rail. One end of the constant motion linear motor is fixed on the air-bearing slide, and the other end is fixed on the micro-slide for driving the air-bearing slide to slide; the linear guide rail is installed on the air-bearing base to provide guidance and support for the movement of the micro-slide.

[0014] Further, the constant motion linear motor has a linear motor stator and a linear motor mover. The linear motor mover is fixed on the air-bearing slide and provides power for it. The linear motor stator is fixed on the micro-slide, and the micro-slide can slide a small distance relative to the air-bearing base through the linear guide rail.

[0015] Further, the voice coil motor has a voice coil motor mover and a voice coil motor stator. A set of the voice coil motors is installed on each side of the micro-moving slide plate. The voice coil motor mover is fixed on the micro-moving slide plate, and the voice coil motor stator is fixed on the air-bearing base.

[0016] The present invention provides an air-bearing workpiece table with active and passive damping functions, and the beneficial effects are as follows:

[0017] By adopting the form of a moving stator, the driving load of the voice coil motor during vibration damping is only the linear motor stator in the constant platform, which can greatly reduce the load mass of the voice coil motor. Furthermore, the stroke of the voice coil motor is shortened, and the servo rigidity of the system is improved; by adopting the form of combining active and passive damping, the passive damping adopts a linear damper, and the active damping adopts a voice coil motor. This method can reduce the output thrust of the voice coil motor during vibration damping, reduce the output power of the voice coil motor, reduce its heat generation, reduce the thermal deformation of the material caused, and provide higher working stability; by adopting the feedback system of the moving stator and the constant moving platform, which does not move with the voice coil motor, the position fed back is theoretically the true position of the moving tabletop. This method can integrate the micro-moving system driven by the voice coil motor into the constant moving system, and the overall volume of the system is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is a top view of an air-bearing workpiece table with active and passive damping functions provided by an embodiment of the present invention;

[0020] Figure 2 It is a cross-sectional view of the transverse installation structure of the air-bearing base and the air-bearing slide plate provided by an embodiment of the present invention;

[0021] Figure 3 is Figure 2 the enlarged view in

[0022] Figure 4 is Figure 2 another enlarged view in

[0023] Figure 5 It is a cross-sectional view of the longitudinal installation structure of an air-bearing workpiece table with active and passive damping functions provided by an embodiment of the present invention;

[0024] Figure 6Mechanical model for force analysis of the air-bearing worktable in the experimental example of the present invention;

[0025] Figure 7 Mechanical model for force analysis of the air-bearing worktable under underdamped conditions in the experimental example of the present invention;

[0026] Figure 8 In the experimental example of the present invention Figure 7 Motor primary displacement diagram under underdamped conditions of the mechanical model;

[0027] Figure 9 In the experimental example of the present invention Figure 7 Base force diagram under underdamped conditions of the mechanical model;

[0028] Figure 10 Mechanical model for force analysis of the air-bearing worktable under the condition of adding a passive damper in the experimental example of the present invention;

[0029] Figure 11 In the experimental example of the present invention Figure 9 Motor primary displacement diagram under the condition of a damping ratio of 0.3 of the mechanical model;

[0030] Figure 12 In the experimental example of the present invention Figure 9 Base force diagram under the condition of a damping ratio of 0.3 of the mechanical model;

[0031] Figure 13 In the experimental example of the present invention Figure 9 Motor primary displacement diagram under critical damping conditions of the mechanical model;

[0032] Figure 14 In the experimental example of the present invention Figure 9 Base force diagram under critical damping conditions of the mechanical model;

[0033] Figure 15 Mechanical model for force analysis of the air-bearing worktable under the conditions of adding passive vibration suppression and active vibration suppression in the experimental example of the present invention;

[0034] Figure 16 In the experimental example of the invention Figure 15 Motor primary displacement diagram under the condition of not adding a voice coil of the mechanical model;

[0035] Figure 17 In the experimental example of the present invention Figure 15 Base force diagram under the condition of not adding a voice coil of the mechanical model;

[0036] Figure 18 In the experimental example of the present invention Figure 15 Base force diagram under the condition of adding a voice coil of the mechanical model;

[0037] Figure 19 In the experimental example of the present inventionFigure 15 Force diagram of the base under the condition of adding a voice coil to the mechanical model.

[0038] In the figure: 1 - air - floating base; 2 - air - floating slide; 3 - constant - motion feedback system; 31 - first reading head; 32 - first grating scale; 33 - grating scale support; 34 - reading head support; 4 - constant - motion linear motor; 41 - linear motor stator; 42 - linear motor mover; 5 - micro - motion slide; 6 - linear guide; 7 - micro - motion feedback system; 71 - second reading head; 72 - second grating scale; 8 - voice coil motor; 81 - voice coil motor mover; 82 - voice coil motor stator; 9 - linear damper. Specific implementation manners

[0039] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0040] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0041] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0042] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be welding, bolt connection, or riveting; it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0043] Embodiment:

[0044] According to Figures 1 to 19As shown in the figure, this embodiment provides a pneumatic workpiece table with active and passive damping functions, including: a pneumatic base 1, a pneumatic slide 2, a micro-slide 5, a voice coil motor 8, a linear damper 9, a constant motion feedback system 3, and a micro-motion feedback system 7. There is an air film gap between the pneumatic slide 2 and the pneumatic base 1, and the pneumatic slide 2 slides along the pneumatic base 1; the micro-slide 5 is installed on the pneumatic base 1; the voice coil motors 8 are installed at both ends of the micro-slide 5; one end of the linear damper 9 is installed at the end of the micro-slide 5, and the other end is installed on the pneumatic base 1, and the linear dampers 9 are distributed at both ends of the micro-slide 5 for passive vibration damping; the constant motion feedback system 3 is installed on the pneumatic base 1 for reading and feedbacking the displacement of the pneumatic slide 2; the micro-motion feedback system 7 converts the feedback of the constant motion feedback system 3 into an anti-vibration command to drive the motion of the voice coil motor 8 for active vibration damping.

[0045] Further, the constant motion feedback system 3 includes: a grating scale bracket 33, a reading head bracket 34, a first reading head 31, and a first grating scale 32. The grating scale bracket 33 is fixed on the pneumatic base 1; the reading head bracket 34 is connected to the pneumatic slide 2; the first reading head 31, the first reading head 31 is connected to the pneumatic slide 2 through the reading head bracket 34; the first grating scale 32 is fixed on the pneumatic base 1 through the grating scale bracket 33. When the pneumatic slide 2 slides, it drives the reading head to move, and the first reading head 31 reads the engraved lines of the first grating scale 32 to form the displacement feedback of the pneumatic slide 2.

[0046] Further, according to Figures 1 to 19 As shown in the figure, the micro-motion feedback system 7 includes: a second reading head 71, a second grating scale second 72, and a controller. The second reading head 71 is fixedly installed on the pneumatic base 1; the second grating scale second 72 is installed on the micro-slide 5. The second reading head 71 reads the displacement of the second grating scale second 72 and feeds back the displacement of the micro-slide 5; the controller second grating scale second 72 outputs the feedback information to the controller, providing data support for the controller to realize vibration prediction and output anti-vibration commands. The controller is used to drive the voice coil motor 8.

[0047] Further, according to Figures 1 to 19 As shown in the figure, the device further includes: a constant motion linear motor 4 and a linear guide 6. One end of the constant motion linear motor 4 is fixed on the pneumatic slide 2, and the other end is fixed on the micro-slide 5 for driving the pneumatic slide 2 to slide; the linear guide 6 is installed on the pneumatic base 1 to provide guidance and support for the movement of the micro-slide 5.

[0048] Further, according to Figures 1 to 19 As shown in the figure, the constant motion linear motor 4 has a linear motor stator 41 and a linear motor mover 42. The linear motor mover 42 is fixed on the pneumatic slide 2 and provides power for it. The linear motor stator 41 is fixed on the micro-slide 5, and the micro-slide 5 can slide a small distance relative to the pneumatic base 1 through the linear guide 6.

[0049] Further, according to Figures 1 to 19 As shown, the voice coil motor 8 has a voice coil motor mover 81 and a voice coil motor stator 82. A set of voice coil motors 8 is installed on each side of the micro-moving slide 5. The voice coil motor mover 81 is fixed on the micro-moving slide 5, and the voice coil motor stator 82 is fixed on the air bearing base 1.

[0050] When the system works, the PC generates a motion trajectory and outputs it to the motion system controller. The controller outputs a motion command to the constant motion system driver (the motion command includes instruction information such as the displacement, speed, and acceleration of the motion axis), and then the driver drives the constant motion linear motor 4, thereby driving the air bearing slide 2 to move. The reading head 31 fixed on the air bearing slide 2 reads the actual position information of the air bearing slide 2 and outputs a feedback signal to the controller, thus realizing the full closed-loop control of the motion system. When the constant motion linear motor 4 acts, the linear motor mover 42 drives the air bearing slide. Due to the reciprocity of the force action, the linear motor stator 41 will receive a reverse acting force. When the linear motor stator 41 is directly fixedly installed on the air bearing base 1, this acting force will cause the movement of the air bearing base 1. In ultra-precision motion control, the manifestation of this movement is vibration.

[0051] In this solution, the linear motor stator 41 is installed on the movable micro-moving slide 5. The reaction force generated by the constant motion linear motor 4 will drive the micro-moving slide 5 to move along the linear guide 6. When it moves, it will drive the linear dampers 9 installed on both sides of the micro-moving slide to move, thereby generating linear damping and realizing the effect of passive vibration reduction.

[0052] At the same time, the reading head 71 feeds back the displacement of the micro-moving slide 5 by reading the displacement of the grating scale 72 and outputs the feedback information to the controller. The controller forms a vibration prediction through the acceleration feedforward of the constant motion axis and the feedback information (displacement, speed, acceleration) of the micro-motion axis, and outputs a vibration suppression command, which is output to the micro-motion system driver. The micro-motion system driver drives the voice coil motor 8 to realize the effect of active vibration reduction.

[0053] Experimental Example 1:

[0054] Perform a force analysis on the passive vibration reduction functional platform and obtain a mechanical model, as Figure 6 shown. The forces caused by the platform movement on the motor primary and the base can be simplified as shown in the figure. In the figure, F1 is the force received by the base from the damper, F2 is the force received by the base from the spring, and F3 is the force received by the base for pulling linear motion. When the linear motor moves, the motor gives a force to the motor primary. If this force causes the motor primary to displace, then the motor primary and the base will receive the forces from the damper and the spring. Then there is the relationship:

[0055]

[0056]

[0057] —— Primary quality of the motor;

[0058] —— Primary displacement of the motor, , is the first derivative of, is the second derivative of;

[0059] —— Force of the linear motor;

[0060] —— Stiffness of the return spring;

[0061] C —— Damping coefficient;

[0062] —— Force on the base;

[0063] From this system, it can be obtained that if the return stiffness of the spring is: , L is the maximum stroke of the stator; then the critical damping coefficient of the system: .

[0064] Experimental example 2:

[0065] Simulate the mechanical model of passive vibration damping ability to obtain relevant parameters and their simulation results. The simulation model is as Figure 7 shown. When the passive damper is not added to the system, the system is in an underdamped state. In the figure, FI is the motor thrust, FG is the resultant force on the base, a is the acceleration, v is the velocity, s is the displacement, ∫ is the integral, A is the system stiffness, and Xc is the primary displacement of the motor. At this time, the displacement-time image of the motor primary and the force image on the base can be obtained. From Figure 8 , Figure 9 it can be seen that when the system is impacted by a step signal, oscillation occurs and the oscillation time is relatively long.

[0066] Experimental example 3:

[0067] When a damper is added to the system, the corresponding simulation model is as Figure 10 shown. In the figure, FI is the motor thrust, FG is the resultant force on the base, a is the acceleration, v is the velocity, s is the displacement, ∫ is the integral, A is the system stiffness, the label 9 is the linear damper 9, and Xc is the primary displacement of the motor. Adjust the damping ratio of the system to 3. From Figure 11 and Figure 12An obvious change in the oscillation can be obtained, and both the oscillation time and the oscillation amplitude are reduced;

[0068] When the damping coefficient of the damper is exactly equal to the critical damping coefficient of the system, that is 1, at this time the system starts from Figure 13 and Figure 14 It can be seen that the oscillation is eliminated fastest under the action of the damper.

[0069] Experimental Example 4:

[0070] Simulate the mechanical model of the main and passive vibration reduction capabilities to obtain relevant parameters and their simulation results. In the actual platform production, the damping coefficient of the damper and the spring force coefficient are generally determined by the device and cannot be adjusted according to the actual needs of the industrial site. The present invention introduces a voice coil motor on the above passive damping system to actively adjust the impedance characteristics of the system. The specific simulation model is as Figure 15 shown. In the figure, FI is the motor thrust, FG is the resultant force received by the base, a is the acceleration, v is the velocity, s is the displacement, ∫ is the integral, A is the system stiffness, the label 9 is the linear damper 9, the label 8 is the voice coil motor 8, B is the controller, and Xc is the primary displacement of the motor. The voice coil motor 8 is used as an adjustable damper, adopting a speed mode and pi control. At this time, the commanded speed is 0, Kp is the damping coefficient, and Ki is the stiffness coefficient. As Figures 16 to 19 shown, after adding the voice coil motor, the damping and system stiffness can be adjusted according to different working conditions, and the adjustable method can also compensate for device errors.

[0071] In summary, when using an air-bearing workpiece table with main and passive vibration reduction functions, redundant devices outside the moving platform can be reduced, the control bandwidth of the moving platform can be improved, and the performance of the vibration reduction system is improved by adopting a combination of main and passive vibration reduction.

[0072] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope recorded in the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An air-floating workpiece table with active and passive shock absorption functions, characterized in that: include: Air floating base (1); An air film gap exists between the air floating slide plate (2) and the air floating base (1), and the air floating slide plate (2) slides along the air floating base (1); A micro-motion slide plate (5) mounted on the air-floating base (1); Voice coil motors (8) are mounted on both ends of the micro-motion slide plate (5); A linear damper (9), one end of which is mounted on the end of the micro-motion slide plate (5), and the other end of which is mounted on the air-floating base (1), and the linear damper (9) is distributed at both ends of the micro-motion slide plate (5) for passive vibration reduction; A constant motion feedback system (3) installed on the air-floating base (1) and used for reading and feeding back the displacement of the air-floating slide plate (2); The micro-motion feedback system (7) converts the feedback of the constant-motion feedback system (3) into a vibration suppression instruction to drive the movement of the voice coil motor (8) for active vibration reduction.

2. The air-floating workpiece table with active and passive shock absorption functions according to claim 1, characterized in that: The constant motion feedback system (3) comprises: The grating scale bracket (33) is fixed on the air-floating base (1); A reading head bracket (34) connected to the air floating slide (2); A first reading head (31), the first reading head (31) being connected to the air-floating slide plate (2) via a reading head bracket (34); A first grating ruler (32) is fixed on the air-floating base (1) via a grating ruler bracket (33); when the air-floating slide plate (2) slides, the reading head (31) is driven to move; the first reading head (31) reads the engraved lines of the first grating ruler (32) to form displacement feedback of the air-floating slide plate (2).

3. The air-floating workpiece table with active and passive shock absorption functions according to claim 2, characterized in that: The micro-motion feedback system (7) comprises: A second reading head (71) is fixedly mounted on the air-floating base (1); A second grating ruler (72) is mounted on the micro-motion slide plate (5), and a second reading head (71) reads the displacement of the second grating ruler (72) to feed back the displacement of the micro-motion slide plate (5); The grating ruler (32) outputs feedback information to the controller to provide data support for the controller to achieve vibration prediction and output vibration suppression instructions, and the controller is used to drive the voice coil motor (8).

4. The air-floating workpiece table with active and passive shock absorption functions according to claim 3, characterized in that: Also includes: A constant motion linear motor (4), one end of which is fixed on the air floating slide (2) and the other end of which is fixed on the micro-motion slide (5), and is used to drive the air floating slide (2) to slide; A linear guide rail (6) is mounted on the air-floating base (1) to provide guidance and support for the movement of the micro-motion slide plate (5).

5. The air-floating workpiece table with active and passive shock absorption functions according to claim 4, characterized in that: The constant motion linear motor (4) comprises a linear motor stator (41) and a linear motor mover (42); the linear motor mover (42) is fixed on the air floating slide plate (2) and provides power therefor; the linear motor stator (41) is fixed on the micro-motion slide plate (5); and the micro-motion slide plate (5) can slide a short distance with the air floating base (1) via the linear guide rail (6).

6. The air-floating workpiece table with active and passive shock absorption functions according to claim 5, characterized in that: The voice coil motor (8) comprises a voice coil motor mover (81) and a voice coil motor stator (82); a set of the voice coil motor (8) is installed on each side of the micro-motion slide plate (5); the voice coil motor mover (81) is fixed on the micro-motion slide plate (5); and the voice coil motor stator (82) is fixed on the air-floating base (1).

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