阅读说明：本技术 基于准零刚度磁场的超精密垂直轴重力补偿装置及方法 (Ultra-precise vertical axis gravity compensation device and method based on quasi-zero stiffness magnetic field ) 是由 李星占 苏星 岳友飞 李加胜 姜忠 段方 戴晓静 魏巍 于 2021-07-16 设计创作，主要内容包括：本发明公开了一种基于准零刚度磁场的超精密垂直轴重力补偿装置及方法,包括基座、大行程超精密垂直轴组件、大行程普通精度运动轴组件和运动控制器,大行程超精密垂直轴组件与大行程普通精度运动轴组件的行程均大于20mm；二者可在重力方向上同步运动,大行程超精密垂直轴组件和大行程普通精度运动轴组件间可产生与重力作用方向相反的悬浮力用于重力的补偿；大行程超精密垂直轴组件和大行程普通精度运动轴组件均与所述运动控制器进行电连接。采用悬浮力来对竖直方向移动时的重力进行补偿,通过磁场产生悬浮力来进行重力补偿的方法,其响应速度更快且更加稳定,对大行程超精密垂直轴重力补偿的效果更好,进而降低重力对大行程超精密垂直轴运动的影响。(The invention discloses an ultra-precise vertical axis gravity compensation device and method based on a quasi-zero stiffness magnetic field, which comprises a base, a large-stroke ultra-precise vertical axis component, a large-stroke common-precision motion axis component and a motion controller, wherein the strokes of the large-stroke ultra-precise vertical axis component and the large-stroke common-precision motion axis component are both greater than 20 mm; the two components can synchronously move in the gravity direction, and the suspension force in the direction opposite to the gravity action direction can be generated between the large-stroke ultra-precise vertical shaft component and the large-stroke common-precision motion shaft component for gravity compensation; and the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are electrically connected with the motion controller. The method for compensating the gravity by using the suspension force to compensate the gravity when the vertical-direction movement is carried out and generating the suspension force through the magnetic field has the advantages of higher response speed, higher stability and better effect on the gravity compensation of the large-stroke ultra-precise vertical shaft, thereby reducing the influence of the gravity on the large-stroke ultra-precise vertical shaft movement.)

1. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field is characterized by comprising a base (1), a large-stroke ultra-precise vertical axis component, a large-stroke common-precision motion axis component and a motion controller (2), wherein the large-stroke ultra-precise vertical axis component and the large-stroke common-precision motion axis component are both arranged on the base (1);

the strokes of the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are both larger than 20 mm;

the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly can move in the gravity direction, and a suspension force opposite to the gravity action direction can be generated between the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly;

the large-stroke ultra-precise vertical shaft assembly can be used for connecting an external load (11);

the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are electrically connected with the motion controller (2), and the motion controller (2) can control the following motion of the large-stroke common-precision motion shaft assembly according to a motion instruction of the large-stroke ultra-precise vertical shaft assembly.

2. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 1, wherein the large-stroke ultra-precise vertical axis assembly is slidably arranged on the base (1) through a hydrostatic guideway support structure (3), and the hydrostatic guideway support structure (3) is arranged along the gravity direction;

the large-stroke common-precision motion shaft assembly is arranged on the base (1) in a sliding mode through a ball screw transmission structure (4), and the ball screw transmission structure (4) is arranged along the gravity direction;

the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly are both provided with position feedback devices;

the resolution of a position feedback device of the large-stroke ultra-precise vertical shaft assembly is in a nanometer level, and the position fluctuation of the large-stroke ultra-precise vertical shaft assembly is in a submicron level when the large-stroke ultra-precise vertical shaft assembly moves;

the resolution of the position feedback device of the large-stroke common-precision motion shaft assembly is in the magnitude of tens of microns, and the position fluctuation of the large-stroke common-precision motion shaft assembly is in the magnitude of sub-millimeters during motion.

3. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 2, wherein the large-stroke ultra-precise vertical axis assembly comprises a rigid connecting piece a (5), a slide carriage a (6) and a magnetic suspension stator (7), the slide carriage a (6) is connected with the hydrostatic guideway support structure (3), and the slide carriage a (6) can slide up and down along the hydrostatic guideway support structure (3);

one end of the rigid connecting piece a (5) is connected with the slide carriage a (6), and the other end of the rigid connecting piece a (5) is connected with the magnetic suspension stator (7).

4. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 3, wherein the large-stroke common precision motion shaft assembly comprises a rigid connecting piece b (8), a slide carriage b (9) and a magnetic levitation rotor (10), the slide carriage b (9) is connected with the ball screw transmission structure (4), and the slide carriage b (9) can slide up and down along the ball screw transmission structure (4);

one end of the rigid connecting piece b (8) is connected with the slide carriage b (9), and the other end of the rigid connecting piece b (8) is connected with the magnetic levitation rotor (10).

5. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 4, wherein the magnetic suspension stator (7) and the magnetic suspension rotor (10) are close to each other and generate suspension force opposite to the action direction of gravity;

a gap of 1 mm-3 mm is formed between the magnetic suspension stator (7) and the magnetic suspension rotor (10).

6. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 5, wherein the rigid connector b (8) comprises a connecting section b (81) for connecting a slide carriage b (9) and a mounting section b (82) for mounting a magnetic levitation rotor (10), the connecting section b (81) is vertically arranged, and the connecting section b (81) is arranged at 90 degrees to the mounting section b (82);

the rigid connecting piece a (5) comprises a connecting section a (51) for connecting the slide carriage a (6), a middle section (52) for avoiding the mounting section b (82) and a mounting section a (53) for mounting the magnetic suspension stator (7), one end of the middle section (52) is connected with the connecting section a (51), and the other end of the middle section (52) is connected with the mounting section a (53);

the mounting section a (53) and the mounting section b (82) are arranged in parallel.

7. The ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 5, wherein the large-stroke ultra-precise vertical axis assembly is arranged below the large-stroke common-precision motion axis assembly;

the magnetic suspension stator (7) is arranged above the magnetic suspension rotor (10);

the external load (11) can be connected to the carriage a (6).

8. The gravity compensation method adopting the ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 3, is characterized by comprising the following steps:

the method comprises the following steps: setting the suspension force, wherein the suspension force is used for balancing the sum of the gravity of the rigid connecting piece a (5), the magnetic suspension stator (7) of the slide carriage a (6) and the external load (11);

step two: and the motion controller 2 controls the motion of the large-stroke ultra-precise vertical shaft assembly and simultaneously controls the following motion of the large-stroke common-precision motion shaft assembly relative to the large-stroke ultra-precise vertical shaft assembly, so that a gap of 1-3 mm is ensured to exist between the magnetic suspension stator (7) and the magnetic suspension rotor (10) all the time.

9. The gravity compensation method of the ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field according to claim 8, wherein in the first step, the distance between the magnetic suspension stator (7) and the magnetic suspension rotor (10) is firstly adjusted to 1 mm-3 mm, the magnetic field stiffness between the magnetic suspension stator and the magnetic suspension rotor is ensured to be lower than 0.4N/mm, the suspension force is ensured not to be changed sharply, and the sum of the gravity of the rigid connecting piece a (5), the slide carriage a (6), the magnetic suspension stator (7) and the external load (11) can be stably balanced;

in the second step, a motion command Z (t) is given for controlling the motion of the large-stroke ultra-precise vertical shaft assembly;

the motion instruction Z for controlling the large-stroke common-precision motion shaft component is generated according to the following method₂(t)：

Firstly, setting a threshold value Z equal to 1mm, when the variation of the motion command Z (t) in any time interval is less than Z, calculating the average value of Z (t) in the time interval, and assigning the average value to Z₂' (t), and then obtaining Z at different time periods₂′(t)；

At Z₂' t), a sinusoidal signal for reducing random disturbance caused by friction, clearance and the like in the motion process of the large-stroke common-precision motion shaft assembly is superposed, the fixed frequency f of the sinusoidal signal needs to be higher than the working frequency of the large-stroke ultra-precision vertical shaft assembly, the amplitude of the sinusoidal signal is smaller than 10 microns, and finally a motion instruction Z for controlling the motion of the large-stroke common-precision motion shaft assembly is obtained₂(t)；

And finally, a notch filter with fixed frequency f is added in the motion control of the large-stroke ultra-precise vertical shaft assembly and is used for offsetting the influence of regular disturbance introduced by a sinusoidal signal and finally realizing gravity compensation in a large stroke.

Technical Field

The invention relates to the field of ultra-precise motion platforms and ultra-precise machining equipment, in particular to an ultra-precise vertical axis gravity compensation device and method based on a quasi-zero stiffness magnetic field.

Background

The ultra-precise vertical axis is easy to generate structural deformation, dynamic characteristic change and servo performance change under the action of gravity, and the vertical motion precision and the dynamic response speed are seriously influenced. The current ultra-precise vertical axis generally adopts a frictionless or low-friction cylinder to form a gravity compensation device, controls the stability of pressure in the cylinder through a pressure reducing valve, a quick exhaust valve and the like, and provides a compensation force equal to gravity. However, because of the extreme compressibility of gas and the delay of pneumatic elements such as a pressure reducing valve and a quick exhaust valve, the in-cylinder pressure in vertical motion inevitably fluctuates and the response speed is much lower than that of a motor driving system. In addition, the connection between the cylinder and the vertical motion part adopts rigid mechanical connection or flexible connection such as a floating joint, and the like, so that the dynamic characteristic of the cylinder is mutually coupled with the vertical motion part, the complexity of a motion system is increased, and a clearance link is inevitably introduced into the floating joint, and finally the vertical motion precision and controllability are seriously influenced. In conclusion, the conventional gravity compensation device cannot quickly and stably compensate the gravity of the large-stroke ultra-precise vertical shaft, so that the gravity influences the motion of the large-stroke ultra-precise vertical shaft. In view of this, the present application is specifically made.

Disclosure of Invention

The invention aims to provide an ultra-precise vertical axis gravity compensation device and method based on a quasi-zero stiffness magnetic field, which can realize the rapid and stable compensation of the large-stroke ultra-precise vertical axis gravity and reduce the influence of the gravity on the large-stroke ultra-precise vertical axis motion.

The invention is realized by the following technical scheme:

an ultra-precise vertical axis gravity compensation device based on a quasi-zero stiffness magnetic field comprises a base, a large-stroke ultra-precise vertical axis assembly, a large-stroke common-precision motion axis assembly and a motion controller, wherein the large-stroke ultra-precise vertical axis assembly and the large-stroke common-precision motion axis assembly are arranged on the base; the strokes of the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are both larger than 20 mm; the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly can move in the gravity direction, and a suspension force opposite to the gravity action direction can be generated between the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly; the large-stroke ultra-precise vertical shaft assembly can be used for connecting an external load; the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are electrically connected with the motion controller, and the motion controller can control the following motion of the large-stroke common-precision motion shaft assembly according to the motion condition of the large-stroke ultra-precise vertical shaft assembly. Aiming at the problem that the existing gravity compensation device cannot realize rapid and stable compensation of the ultra-compact vertical axis gravity in a large stroke, the invention adopts the suspension force to compensate the gravity when moving in the vertical direction, and compared with the cylinder gravity compensation method, the method for generating the suspension force through the magnetic field to perform the gravity compensation has the advantages of higher response speed and more stability, better gravity compensation effect on a large-stroke ultra-compact vertical axis assembly, and further reduces the influence of the gravity on the large-stroke ultra-compact vertical axis motion.

The further technical scheme is as follows:

the large-stroke ultra-precise vertical shaft assembly is arranged on the base in a sliding mode through a static pressure guide rail supporting structure, and the static pressure guide rail supporting structure is arranged along the gravity direction; the hydrostatic guideway support structure has extremely high motion precision, so that the hydrostatic guideway support structure can further enhance the quick and stable compensation capability of the device on gravity, and further reduce the influence of gravity on the large-stroke ultra-precise vertical axis motion.

Further: the large-stroke common-precision motion shaft assembly is arranged on the base in a sliding mode through a ball screw transmission structure, and the ball screw transmission structure is arranged along the gravity direction; the ball screw transmission structure has extremely high rigidity in the motion direction, can still keep stable when bearing larger force, can provide stable suspension force for the large-stroke ultra-precise vertical shaft by combining the magnetic suspension structure to compensate gravity, and further reduces the influence of the gravity on the large-stroke ultra-precise vertical shaft motion.

Further: the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly are both provided with position feedback devices;

further: the resolution of a position feedback device of the large-stroke ultra-precise vertical shaft assembly is in a nanometer level, and the position fluctuation of the large-stroke ultra-precise vertical shaft assembly is in a submicron level when the large-stroke ultra-precise vertical shaft assembly moves;

further: the resolution of the position feedback device of the large-stroke common-precision motion shaft assembly is in the magnitude of tens of microns, and the position fluctuation of the large-stroke common-precision motion shaft assembly is in the magnitude of sub-millimeters during motion.

Further: the large-stroke ultra-precise vertical shaft assembly comprises a rigid connecting piece a, a slide carriage a and a magnetic suspension stator, wherein the slide carriage a is connected with the hydrostatic guideway supporting structure and can slide up and down along the hydrostatic guideway supporting structure;

further: one end of the rigid connecting piece a is connected with the slide carriage a, and the other end of the rigid connecting piece a is connected with the magnetic suspension stator.

Further: the large-stroke common-precision motion shaft assembly comprises a rigid connecting piece b, a slide carriage b and a magnetic levitation rotor, wherein the slide carriage b is connected with the ball screw transmission structure and can slide up and down along the ball screw transmission structure;

further: one end of the rigid connecting piece b is connected with the slide carriage b, and the other end of the rigid connecting piece b is connected with the magnetic levitation rotor.

Further: the magnetic suspension stator and the magnetic suspension rotor approach each other to generate suspension force in the direction opposite to the action direction of gravity;

further: the magnetic suspension stator and the magnetic suspension rotor are not contacted, and a gap of 1-3 mm exists.

Further: the rigid connecting piece b comprises a connecting section b for connecting the slide carriage b and an installation section b for installing a magnetic levitation rotor, the connecting section b is vertically arranged, and the connecting section b and the installation section b are arranged at an angle of 90 degrees;

further: the rigid connecting piece a comprises a connecting section a for connecting the slide carriage a, a middle section for avoiding the mounting section b and a mounting section a for mounting the magnetic suspension stator, one end of the middle section is connected with the connecting section a, and the other end of the middle section is connected with the mounting section a;

further: the mounting section a and the mounting section b are arranged in parallel.

Further: the large-stroke ultra-precise vertical shaft assembly is arranged below the large-stroke common-precision moving shaft assembly, and the magnetic suspension stator of the large-stroke ultra-precise vertical shaft assembly is arranged above the magnetic suspension rotor;

further: the external load may be connected to the carriage a.

The gravity compensation method of the ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field comprises the following steps:

the method comprises the following steps: setting suspension force, wherein the suspension force is used for balancing the sum of the gravity of the rigid connecting piece a, the magnetic suspension stator of the slide carriage a and an external load;

step two: and the motion controller 2 controls the following motion of the large-stroke ultra-precise vertical shaft assembly while controlling the motion of the large-stroke ultra-precise vertical shaft assembly, so that a gap of 1-3 mm is ensured to exist between the magnetic suspension stator and the magnetic suspension rotor.

Further: firstly, adjusting the distance between a magnetic suspension stator and a magnetic suspension rotor to be 1-3 mm, ensuring that the magnetic field rigidity between the magnetic suspension stator and the magnetic suspension rotor is lower than 0.4N/mm, ensuring that the suspension force does not have the condition of rapid change and stably balancing the sum of the gravity of a rigid connecting piece a, a magnetic suspension stator of a slide carriage a and an external load;

in the second step, a motion command Z (t) is given for controlling the motion of the large-stroke ultra-precise vertical shaft assembly;

the motion instruction Z for controlling the large-stroke common-precision motion shaft component is generated according to the following method₂(t)：

Firstly, setting a threshold value Z equal to 1mm, when the variation of the motion command Z (t) in any time interval is less than Z, calculating the average value of Z (t) in the time interval, and assigning the average value to Z₂' (t), and then obtaining Z at different time periods₂′(t)；

At Z₂' t), a sinusoidal signal for reducing random disturbance caused by friction, clearance and the like in the motion process of the large-stroke common-precision motion shaft assembly is superposed, the fixed frequency f of the sinusoidal signal needs to be higher than the working frequency of the large-stroke ultra-precision vertical shaft assembly, the amplitude of the sinusoidal signal is smaller than 10 microns, and finally a motion instruction Z for controlling the motion of the large-stroke common-precision motion shaft assembly is obtained₂(t)；

And finally, a notch filter with fixed frequency f is added in the motion control of the large-stroke ultra-precise vertical shaft assembly and is used for offsetting the influence of regular disturbance introduced by a sinusoidal signal and finally realizing gravity compensation in a large stroke. By using the method for the ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field, the disturbance of a large-stroke ultra-precise vertical axis component caused by the following motion of a large-stroke common-precision motion axis component can be effectively reduced, meanwhile, the random disturbance caused by friction, gaps and the like during the motion of the large-stroke common-precision motion axis component is reduced by adding a sine signal with fixed frequency f, the regularity of the fluctuation of the suspension force for gravity compensation is realized, and a notch filter with fixed frequency f is added in the control of the large-stroke ultra-precise vertical axis component, so that the influence of the regularity disturbance introduced by the sine signal is counteracted, and finally the gravity compensation of the large-stroke ultra-precise vertical axis is realized.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. according to the ultra-precise vertical axis gravity compensation device and method based on the quasi-zero stiffness magnetic field, the suspension force is adopted to compensate the gravity when the device moves in the vertical direction, and compared with an air cylinder gravity compensation method, the method for performing gravity compensation by generating the suspension force through the magnetic field has the advantages that the response speed is higher and more stable, the effect of large-stroke ultra-precise vertical axis gravity compensation is better, and the influence of the gravity on large-stroke ultra-precise vertical axis motion is further reduced;

2. the invention relates to an ultra-precise vertical axis gravity compensation device and method based on a quasi-zero stiffness magnetic field, which realize the movement of an ultra-precise vertical axis and a common precise motion axis in a large stroke through a hydrostatic guideway supporting structure and a ball screw transmission structure;

3. according to the ultra-precise vertical axis gravity compensation device and method based on the quasi-zero stiffness magnetic field, a ball screw transmission structure has extremely high stiffness in the motion direction, can still keep stable when bearing large force, can provide stable suspension force by combining with a magnetic suspension structure, and can perform stable gravity compensation on a large-stroke ultra-precise vertical axis.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic structural view of a rigid connection member a according to the present invention;

FIG. 3 is a schematic view of the structure of the present invention

FIG. 4 is a diagram of motion command versus time according to the present invention.

Reference numbers and corresponding part names in the drawings:

the method comprises the following steps of 1-a base, 2-a motion controller, 3-a hydrostatic guideway support structure, 4-a ball screw transmission structure, 5-a rigid connecting piece a, 6-a slide carriage a, 7-a magnetic suspension stator, 8-a rigid connecting piece b, 9-a slide carriage b, 10-a magnetic suspension rotor, 11-an external load, 51-a connecting section a, 52-a middle section, 53-an installation section a, 81-a connecting section b and 82-an installation section b.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail so as not to obscure the present invention.

Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the description of the present invention, the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore, should not be construed as limiting the scope of the present invention.

Example 1:

as shown in fig. 1 to 3, the ultra-precise vertical axis gravity compensation device based on the quasi-zero stiffness magnetic field comprises a base 1, a large-stroke ultra-precise vertical axis assembly, a large-stroke common-precision motion axis assembly and a motion controller 2, wherein the large-stroke ultra-precise vertical axis assembly and the large-stroke common-precision motion axis assembly are both arranged on the base 1; the base 1 is used for installing each component of the device, and meanwhile, the large-stroke ultra-precise vertical shaft component and the large-stroke common-precision motion shaft component can move on the base 1, so that the large-stroke ultra-precise vertical shaft component can move in a large stroke.

The strokes of the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are both larger than 20 mm; in the embodiment, the stroke of the shaft assembly is larger than 20mm, and compared with the micron-sized stroke of the precision motion shaft gravity compensation device adopting the magnetic levitation technology at present, the stable and effective suspension force can be effectively provided for the large-stroke ultra-precision vertical shaft to overcome the gravity, so that the influence of the gravity on the large-stroke ultra-precision vertical shaft motion is reduced.

The large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly can move in the gravity direction, and a suspension force opposite to the gravity action direction can be generated between the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly; in this embodiment, the motion condition of the large-stroke common-precision motion shaft assembly is based on the motion condition of the large-stroke ultra-precision vertical shaft assembly, the change of the relative position between the two is very small in the motion process, and the relative position between the two can be regarded as unchanged, so that a stable suspension force for compensating gravity can be generated between the two all the time, and the gravity of the large-stroke ultra-precision vertical shaft assembly and the load can be effectively compensated.

And the large-stroke ultra-precise vertical shaft assembly can be used for connecting an external load 11; the external load 11 is borne by the large-stroke ultra-precise vertical shaft assembly in the embodiment; meanwhile, the external load 11 can be arranged at other positions of the large-stroke ultra-precise vertical shaft assembly, and the external load 11 can move along with the large-stroke ultra-precise vertical shaft assembly.

The large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision motion shaft assembly are electrically connected with the motion controller 2, and the motion controller 2 can control the following motion of the large-stroke common-precision motion shaft assembly according to a motion command of the large-stroke ultra-precise vertical shaft assembly. In the embodiment, the two shaft assemblies move in an electric control mode, so that the control effect is better, the generated suspension force is more stable, and the large-stroke ultra-precise vertical shaft assembly and the gravity of a load can be effectively compensated; meanwhile, the motion of the large-stroke common-precision motion shaft assembly is based on the motion condition of the large-stroke ultra-precision vertical shaft assembly, the motion between the large-stroke common-precision motion shaft assembly and the large-stroke ultra-precision vertical shaft assembly can be considered to be performed synchronously, the distance between the large-stroke common-precision motion shaft assembly and the large-stroke ultra-precision vertical shaft assembly is almost unchanged, so that the generated suspension force is close to be fixed, and the gravity compensation for the large-stroke ultra-precision vertical shaft assembly and the load is more stable.

The large-stroke ultra-precise vertical shaft assembly is arranged on the base 1 in a sliding mode through a static pressure guide rail supporting structure 3, and the static pressure guide rail supporting structure 3 is arranged along the gravity direction; the vertically arranged hydrostatic guideway support structures 3 in this embodiment are used to enable movement of the large-stroke ultra-precision vertical axis assembly in the vertical direction.

The large-stroke common-precision motion shaft assembly is arranged on the base 1 in a sliding mode through a ball screw transmission structure 4, and the ball screw transmission structure 4 is arranged along the gravity direction; the vertically arranged ball screw transmission structure 4 in this embodiment is used for realizing the movement of the large-stroke common-precision motion shaft assembly in the vertical direction.

The large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly are both provided with position feedback devices; the resolution of a position feedback device of the large-stroke ultra-precise vertical shaft assembly is in a nanometer level, and the position fluctuation of the large-stroke ultra-precise vertical shaft assembly is in a submicron level when the large-stroke ultra-precise vertical shaft assembly moves; the resolution of the position feedback device of the large-stroke common-precision motion shaft assembly is in the magnitude of tens of microns, and the position fluctuation of the large-stroke common-precision motion shaft assembly is in the magnitude of sub-millimeters during motion. In order to realize the position monitoring of the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly, so that the movement of the large-stroke ultra-precise vertical shaft assembly and the large-stroke common-precision moving shaft assembly can be better controlled, and the transmission characteristic of the hydrostatic guideway support structure 3 is combined, the large-stroke ultra-precise vertical shaft assembly is monitored by adopting a grating ruler in the embodiment, and the displacement information of the large-stroke ultra-precise vertical shaft assembly is monitored by utilizing the advantages of large detection range, high detection precision, high response speed and the like, so that the position information of the large-stroke ultra-precise vertical shaft assembly is monitored; in combination with the transmission characteristic of the ball screw transmission structure, the motor code wheel is adopted to monitor the large-stroke common-precision moving shaft assembly in the embodiment, and the displacement information of the large-stroke common-precision moving shaft assembly is monitored by utilizing the advantages of strong resolution capability, high measurement precision, reliable work and the like of the motor code wheel, so that the position information of the large-stroke common-precision moving shaft assembly is monitored. The position feedback device is used for feeding back the position information of the large-stroke ultra-precise vertical shaft assembly and the position information of the large-stroke common-precision motion shaft assembly in real time, so that the motion controller 2 is ensured to control the shaft assembly more accurately, and stable compensation of the large-stroke ultra-precise vertical shaft gravity can be realized under the condition that the high-precision feedback device is not needed.

The large-stroke ultra-precise vertical shaft assembly comprises a rigid connecting piece a5, a slide carriage a6 and a magnetic levitation stator 7, wherein the slide carriage a6 is connected with the hydrostatic guideway support structure 3, and the slide carriage a6 can slide up and down along the hydrostatic guideway support structure 3; in the embodiment, the large-stroke ultra-precise vertical shaft assembly is connected with the hydrostatic guideway support structure 3 through the slide carriage a6, and the precise motion of the large-stroke ultra-precise vertical shaft assembly is realized by utilizing the characteristic of small frictional resistance in the transmission process of the hydrostatic guideway 3 and matching with a high-precision driving motor.

One end of the rigid connecting piece a5 is connected with the slide carriage a6, and the other end of the rigid connecting piece a5 is connected with the magnetic levitation stator 7. In the embodiment, the connection between the slide carriage a6 and the magnetic suspension stator 7 is realized by utilizing the characteristics of high connection strength, reliable connection and the like of the rigid connecting piece a5, the suspension force can be effectively used for compensating the gravity of the large-stroke ultra-precise vertical shaft, and the connection relationship cannot be damaged.

The large-stroke common-precision motion shaft assembly comprises a rigid connecting piece b8, a slide carriage b9 and a magnetic levitation rotor 10, wherein the slide carriage b9 is connected with the ball screw transmission structure 4, and the slide carriage b9 can slide up and down along the ball screw transmission structure 4; in the embodiment, the large-stroke common-precision moving shaft assembly is connected with the ball screw transmission structure 4 through the slide carriage b9, and the characteristics of high rigidity, large bearing capacity and the like of the transmission of the ball screw transmission structure 4 in the moving direction are utilized to realize the precise movement of the large-stroke common-precision moving shaft assembly in cooperation with a high-precision driving motor.

One end of the rigid connecting piece b8 is connected with the slide carriage b9, and the other end of the rigid connecting piece b8 is connected with the magnetic levitation rotor 10. In this embodiment, the rigid connecting member b8 has high connection strength and reliable connection, so that the connection between the slide carriage b9 and the magnetic levitation rotor 10 is realized, the levitation force can be effectively used for compensating the gravity of the large-stroke ultra-precise vertical shaft assembly, and the connection relationship is not damaged. During the movement, the tracking error of the slide carriage b9 needs to be kept within the range of 1000 μm, which is much larger than the tracking error of the slide carriage a6 (generally within 10 μm), the fluctuation magnitude of the relative distance between the two is 1000 μm magnitude, and the fluctuation magnitude of the levitation force is within 0.4N. The influence of the suspension force fluctuation on the servo control of the large-stroke ultra-precise vertical shaft is extremely small, so that the embodiment can stably and effectively compensate the gravity on the large-stroke ultra-precise vertical shaft in motion, and further reduce the influence of the gravity on the large-stroke ultra-precise vertical shaft in motion.

The magnetic suspension stator 7 and the magnetic suspension rotor 10 approach each other to generate a suspension force with a direction opposite to the action direction of gravity; in the embodiment, the large-stroke ultra-precise vertical shaft is subjected to gravity compensation through the suspension force generated by the magnetic suspension stator 7 and the magnetic suspension rotor 10.

The magnetic suspension stator 7 is not contacted with the magnetic suspension rotor 10, and a gap of 1 mm-3 mm exists. When a gap of 1-3 mm exists between the magnetic suspension stator 7 and the magnetic suspension rotor 10, the rigidity of a magnetic field between the magnetic suspension stator and the magnetic suspension rotor is lower than 0.4N/mm, so that the fluctuation of the interaction force of the magnetic field caused by the change of the gap between the magnetic suspension stator and the magnetic suspension rotor can be controlled below 0.8N, and therefore the device can provide stable suspension force to perform gravity compensation on the large-stroke ultra-precise vertical shaft, and further reduce the influence of gravity on the large-stroke ultra-precise vertical shaft motion.

The magnetic levitation rotor 10 comprises a concave part, the magnetic levitation stator 7 comprises a convex part, and the convex part can be inserted into the concave part, is not in contact with the concave part and has a gap of 1-3 mm. In order to prevent the situation that the magnetic levitation stator 7 and the magnetic levitation rotor 10 are dislocated and the like to affect the levitation force in the movement process, the embodiment realizes the connection between the magnetic levitation stator 7 and the magnetic levitation rotor 10 through the contactless plug-in connection mode, and ensures that stable levitation force can be provided to perform gravity compensation on the large-stroke ultra-precise vertical axis, thereby reducing the influence of gravity on the large-stroke ultra-precise vertical axis movement

The rigid connecting piece b8 comprises a connecting section b81 for connecting a slide carriage b9 and a mounting section b82 for mounting a magnetic levitation runner 10, wherein the connecting section b81 is vertically arranged, and the connecting section b81 is arranged at 90 degrees to the mounting section b 82; the rigid connecting piece a5 comprises a connecting section a51 for connecting a slide carriage a6, a middle section 52 for avoiding a mounting section b82 and a mounting section a53 for mounting the magnetic levitation stator 7, one end of the middle section 52 is connected with the connecting section a51, and the other end of the middle section 52 is connected with the mounting section a 53; the mounting section a53 is disposed in parallel with the mounting section b 82.

The large-stroke ultra-precise vertical shaft assembly is arranged below the large-stroke common-precision moving shaft assembly; the magnetic suspension stator 7 is arranged above the magnetic suspension rotor 10; the external load 11 may be connected to a sled a 6. In this embodiment, the slide carriage a6 is disposed below the slide carriage b9 in the vertical direction, but the magnetic levitation stator 7 is mounted above the magnetic levitation rotor 10, so the middle section 52 needs to be designed to avoid the mounting section b 82.

Example 2:

as shown in fig. 1 or fig. 4, a gravity compensation method for an ultra-precise vertical axis gravity compensation device based on a quasi-zero stiffness magnetic field includes the following steps:

the method comprises the following steps: setting of levitation force, wherein the levitation force is used for balancing the sum of the gravity of the rigid connector a5, the slide carriage a6, the magnetic levitation stator 7 and the external load 11; at this time, it should be noted that the driving modes of the large-stroke common-precision motion shaft assembly and the large-stroke ultra-precision vertical shaft assembly are different, and the relative distance between the two assemblies is difficult to avoid in the motion process, so that fluctuation occurs, and the fluctuation can cause the change of the gap between the suspension stator 7 and the magnetic suspension rotor 10. Therefore, it is required to ensure that the gap between the suspension stator 7 and the magnetic suspension rotor 10 is stabilized within the gap range of 1 mm-3 mm, and the magnetic field rigidity value between the suspension stator and the magnetic suspension rotor is quasi-zero rigidity lower than 0.4N/mm, so that the fluctuation of the suspension force caused by the change of the gap can be controlled within 0.8N, thereby ensuring the stable compensation of the large-stroke ultra-precise vertical shaft and the load gravity, and achieving the purpose of reducing the influence of the gravity on the vertical motion of the large-stroke ultra-precise vertical shaft.

Step two: and the motion controller 2 controls the motion of the large-stroke ultra-precise vertical shaft assembly and simultaneously controls the following motion of the large-stroke common-precision motion shaft assembly relative to the large-stroke ultra-precise vertical shaft assembly, so that a gap of 1-3 mm is ensured to exist between the magnetic suspension stator 7 and the magnetic suspension rotor 10 all the time. The corresponding speed of the suspension force generated by the magnetic field in the embodiment is extremely high, the delay of the servo control process of the shaft assembly caused by the gravity compensation device can be greatly reduced, and the compensation effect of the gravity compensation device on the gravity is ensured to meet the working requirement.

Specifically, the method comprises the following steps: firstly, adjusting the distance between a magnetic suspension stator 7 and a magnetic suspension rotor 10 to be 1-3 mm, ensuring that the magnetic field rigidity between the magnetic suspension stator 7 and the magnetic suspension rotor 10 is quasi-zero rigidity lower than 0.4N/mm at the moment, ensuring that the suspension force does not change rapidly, and stably balancing the sum of the gravity of a rigid connecting piece a5, a slide carriage a6 magnetic suspension stator 7 and an external load 11;

in the second step, a motion command Z (t) is given for controlling the motion of the large-stroke ultra-precise vertical shaft assembly;

the motion instruction Z for controlling the large-stroke common-precision motion shaft component is generated according to the following method₂(t)：

Firstly, a threshold value Z is set to be 1mm, and when a motion instruction Z (t) is in any time interval t_i,t_i+1]When the variation in the value of i is smaller than Z, calculating the average value of Z (t) in the time interval, and assigning the average value to Z₂' (t), and then obtaining Z at different time periods₂′(t)；

At Z₂' t), a sinusoidal signal for reducing random disturbance caused by friction, clearance and the like in the motion process of the large-stroke common-precision motion shaft assembly is superposed, the fixed frequency f of the sinusoidal signal needs to be higher than the working frequency of the large-stroke ultra-precision vertical shaft assembly, the amplitude of the sinusoidal signal is smaller than 10 microns, and finally a motion instruction Z for controlling the motion of the large-stroke common-precision motion shaft assembly is obtained₂(t)；

And finally, a notch filter with fixed frequency f is added in the motion control of the large-stroke ultra-precise vertical shaft assembly and is used for offsetting the influence of regular disturbance introduced by a sinusoidal signal and finally realizing gravity compensation in a large stroke.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.