CN105202325B - A kind of big stroke single-degree-of-freedom air supporting Magnetic driving nanopositioning stage - Google Patents

Abstract

The invention discloses a large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform, which comprises an electromagnetic actuator, an air-floating guiding mechanism, a position sensor module, and an eddy current damper module. The body of the electromagnetic actuator is composed of a stator and a mover. The mover part is equipped with a permanent magnet array, and the three-phase winding of the stator adopts an iron-free structure. The air bearing guide mechanism restricts the degrees of freedom of the positioning platform in five directions through three air bearings in the vertical direction and two horizontal air bearings on the sides, so that it can only move in one direction. The position sensor module is realized by a high-precision grating ruler. The eddy current damper module includes two eddy current dampers, which are respectively arranged at the front and rear ends of the electromagnetic actuator. The nano-positioning platform of the present invention has the advantages of simple structure, direct drive, no friction, no hysteresis, no backlash, etc., and can achieve nanometer-level positioning resolution within a movement stroke of tens to hundreds of millimeters.

Description

A large-stroke single-degree-of-freedom air-floating magnetically driven nanopositioning platform

technical field

The invention relates to the field of precision servo drive, in particular to a large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform.

Background technique

With the development of nano-manufacturing technology, high-efficiency nano-machining machine tools, nano-laser direct writing lithography machines, and AFM-based large-scanning-range metrology equipment propose a motion positioning platform with sub-nanometer resolution, Nano-level positioning accuracy and high bandwidth requirements.

The invention patents with patent publication numbers 102998899A and 103883849A use the combination of flexible hinges and piezoelectric ceramics to achieve nano-positioning. This direct-drive piezoelectric ceramic actuator has sub-nanometer positioning resolution, but the processing and The measurement range is only a few tens of microns, and even with an amplifying mechanism, the stroke can only reach a few hundred microns. Indirect piezoelectric ceramic actuators (such as piezoelectric linear motors using standing wave ultrasonic principle and inchworm drive principle) can achieve large displacement and nanometer positioning resolution, but the low repetition rate of this type of piezoelectric ceramic actuator The positioning accuracy makes it unsuitable for large-scale continuous nanofabrication and scanning measurement equipment. The invention patent with the patent publication number 102629122A proposes a macro/micro combination dual-servo motion platform composed of a linear servo motor and a micro motion platform. This limits the bandwidth of the entire platform, reducing the efficiency of nanofabrication and scanning measurements. Therefore, those skilled in the art are devoting themselves to developing a new configuration of a large-travel nanopositioning platform.

Contents of the invention

In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to improve the precision, simplify the structure and reduce the volume of the existing large-stroke nanopositioning platform.

In order to achieve the above object, the present invention provides a large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform, which includes a positioning platform mechanical body and a positioning platform controller. The positioning platform mechanical body includes an electromagnetic drive actuator, an air-floating A guiding mechanism and an eddy current damper module, wherein the electromagnetic drive actuator is configured to generate electromagnetic force to realize the change of platform displacement; the air bearing guiding mechanism is configured to make the platform move in only one direction; the electric The eddy current damper module is configured to generate a damping force to shorten the positioning time of the positioning platform.

Further, the electromagnetic drive actuator is composed of a stator and a mover, the stator is made of three-phase winding copper wires, the electrical phase difference of each phase winding is 120 degrees, and adopts a coreless structure; the mover Composed of a magnetic array, the arrangement of the magnetic array is configured to ensure that the magnetic field strength is strong on the side facing the winding, and the magnetic field strength is weak on the side facing away from the winding; the phase and magnitude of the energized current of the stator three-phase winding are configured as Change the magnitude of thrust in the single-degree-of-freedom direction of the positioning platform.

Further, the air flotation guide mechanism includes marble guide rails, a first air flotation module, a second air flotation module, a third air flotation module, a fourth air flotation module and a fifth air flotation module; the first air flotation module configured to limit the degree of freedom of the positioning platform in the vertical direction, the second air bearing module is configured to limit the degree of freedom of the positioning platform in the pitch direction, and the third air bearing module is configured to limit the degree of freedom of the positioning platform in the yaw direction , the fourth air flotation module is configured to limit the degree of freedom of the positioning platform in the horizontal direction, and the fifth air flotation module is configured to limit the degree of freedom of the positioning platform in the yaw direction.

Further, the eddy current damping module is composed of a copper plate and a winding, the copper plate is fixed on the stator of the positioning platform, and moves with the positioning platform; the winding is wound on the silicon steel sheet, and the two windings form a closed magnetic field; at the same speed , the magnitude of the current in the control winding is configured to control the strength of the magnetic field, thereby controlling the magnitude of the damping force.

Further, the positioning platform controller is controlled by a linear drive circuit, including a main controller, an A/D conversion circuit, a D/A conversion circuit, a linear amplification module, a current sensor and a position sensor; the main controller is configured In order to run the control algorithm and the positioning platform driving algorithm; the A/D conversion circuit is configured to sample the current signal output by the current sensor to complete the current loop control of the positioning platform; the D/A conversion circuit is configured to The digital current signal output by the main controller is converted into an analog current signal; the linear amplification module is configured to amplify the analog current signal to drive the stator winding; the current sensor is configured to collect the stator current signal; the The position sensor is configured to collect the position of the mover of the positioning platform.

Further, the frame of the stator is made of aluminum alloy.

Further, the magnetic array is bonded to the frame of the stator.

Further, the magnetic array formed by four magnet blocks is configured to form an electrical cycle.

Further, the first air flotation module, the second air flotation module and the third air flotation module are arranged in a triangle.

Further, the first air flotation module, the second air flotation module, the third air flotation module, the fourth air flotation module and the fifth air flotation module adopt porous vacuum pre-pressurized air floating bearing.

The single-degree-of-freedom air-floating magnetically driven nano-positioning platform described in the patent of the present invention includes a positioning platform mechanical body and a positioning platform controller. The positioning platform body described in the patent of the present invention includes an electromagnetic drive actuator, an air bearing guide mechanism, a position sensor and an eddy current damper module. The electromagnetic drive actuator generates electromagnetic force to realize the change of platform displacement; the air bearing guide mechanism is used to limit the degree of freedom of the platform in other directions, so that the platform can only move in one direction; the position sensor is the position feedback signal of the positioning platform; the eddy current damper The module generates a damping force to shorten the positioning time of the positioning platform.

The electromagnetic drive actuator described in the patent of the present invention is composed of a stator and a mover. The stator is made of three-phase winding copper wires, and the electrical phase difference of each phase winding is 120 degrees. It adopts a coreless structure; Composition, the arrangement of the magnetic array ensures that the magnetic field strength is strong on the side facing the winding, and the magnetic field strength is weak on the side facing away from the winding. Changing the phase and magnitude of the energized current of the stator three-phase winding can change the thrust of the positioning platform in the single degree of freedom direction.

The positioning platform controller described in the patent of the present invention is controlled by a linear drive circuit to overcome the noise caused by digital signal drive, including the main controller, A/D conversion circuit, D/A conversion circuit, linear amplification module, current sensor and Position sensor acquisition and other modules. The main controller completes the control algorithm and the driving algorithm of the positioning platform; the A/D conversion circuit samples the current signal output by the current sensor to complete the current loop control of the positioning platform; the D/A conversion circuit converts the digital current signal output by the controller into an analog Current signal; the linear amplification module amplifies the current signal to drive the stator winding; the current sensor collects the stator current signal; the position sensor collects the position of the mover of the positioning platform.

The eddy current damping module described in the patent of the present invention is composed of copper plates and windings. The copper plate is fixed on the stator of the positioning platform and moves with the positioning platform; the winding is wound on the silicon steel sheet, and the two windings form a closed magnetic field. At the same speed, controlling the magnitude of the current in the winding can control the strength of the magnetic field, thereby controlling the magnitude of the damping force.

The patent of the present invention proposes a large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform, which meets the requirements of nano-processing and scanning measurement equipment for large-stroke motion and nano-level positioning accuracy of the positioning platform. The proposed single-degree-of-freedom air-floating magnetically driven nanopositioning platform has the advantages of simple structure, direct drive, no friction, no hysteresis, and no backlash gap, etc., and can achieve nanometer-level positioning resolution within tens to hundreds of millimeters of motion travel. .

The idea, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of drawings

Fig. 1 is the overall schematic diagram of the nanopositioning platform of a preferred embodiment of the present invention;

Fig. 2 is a schematic diagram of the nanopositioning platform mechanical body of a preferred embodiment of the present invention;

Fig. 3 is a schematic diagram of an electromagnetic actuator of a preferred embodiment of the present invention;

Fig. 4 is a schematic diagram of the structure of the air-floating guide rail in a preferred embodiment of the present invention;

Fig. 5 is a schematic diagram of an eddy current damping module of a preferred embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a nanopositioning platform controller in a preferred embodiment of the present invention.

detailed description

The present invention will be described in detail below in conjunction with specific implementation cases.

As shown in FIG. 1 , the patent of the present invention proposes a large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform, which includes a positioning platform mechanical body 100 and a positioning platform controller 200 . The positioning platform controller 200 collects current signals and position signals in the mechanical body 100 , and controls the mechanical body 100 to move in a single-degree-of-freedom direction to realize nanoscale precision movement with a large stroke.

As shown in FIG. 2 , the mechanical body 100 includes an electromagnetic actuator 110 , an air bearing guide mechanism 120 , a position feedback grating scale 130 and an eddy current damping module 140 . The electromagnetic actuator 110 includes a stator and a mover. The three-phase A winding 112 , B winding 113 and C winding 114 of the stator are wound on the stator frame 111 according to the phase difference 120 , as shown in FIG. 3 . In order to generate an ideal sine wave magnetic flux density as much as possible in the gap between the stator and the mover, and reduce the influence of cogging on the back electromotive force of the electromagnetic actuator 110, the stator frame 111 is made of aluminum alloy. The permanent magnet array 116 is fixed on the mover frame 115 by adhesive. The arrangement sequence of the permanent magnets in the permanent magnet array 116 is shown in FIG. 3 , the arrows in the figure indicate the direction of the magnetic field, and four permanent magnet blocks form an electrical cycle. The permanent magnet array 116 has a strong magnetic field in the gap between the stator and the mover, and a weak magnetic field above the permanent magnet array.

Fig. 4 shows a schematic diagram of the air flotation guide rails, in which the marble guide rails 121 and 125 are the contact surfaces of the air flotation modules. Wherein the air flotation module 122, the air flotation module 123 and the air flotation module 124 are arranged in a triangle to limit the degrees of freedom of the positioning platform in the vertical direction, pitch direction and yaw direction; the air flotation module 126 and the air flotation module 127 limit the positioning platform to a horizontal direction and degrees of freedom in the yaw direction. The positioning platform moves linearly in one direction through five air flotation modules and guide rails. The air bearing adopts a porous vacuum preloaded air bearing module.

The structure of the eddy current damper module is shown in FIG. 5 , the module consists of a copper plate 141 , a lower winding 142 , an upper winding 143 and a winding frame 144 . The windings of the lower winding 142 and the upper winding 143 are connected in series so that the magnetic field direction passes through the copper plate 141 vertically from the upper winding 143 to the lower winding 142 or from the lower winding 142 to the upper winding 143 . The copper plate 141 is fixed together with the mover of the positioning platform, and the mover of the positioning platform drives the copper plate 141 to move when moving, so that the eddy current signal formed in the copper plate generates a certain damping force. Controlling the magnitude of the current in the lower winding 143 and the upper winding 142 can control the magnitude of the damping force.

The structure diagram of the control system of the nanopositioning platform is shown in FIG. 6 , including a main controller 210 , an A/D converter 220 , a current sensor 230 , a linear amplification module 240 , a D/A converter 250 and a grating ruler 260 . The high-precision grating ruler with an output signal of 1Vpp is subdivided to reach nanometer resolution, and is used to sensor the displacement of the mover of the nanopositioning platform. The main controller 210 uses an industrial control computer to complete the control of the current loop, speed loop and position loop of the nanopositioning platform. The current sensor 230 converts the current signal of the stator winding of the nanopositioning platform into a voltage signal. The A/D conversion module 220 adopts 18-bit and above high-resolution conversion devices to improve the control accuracy of the current. The D/A conversion module 250 converts the digital current signal calculated by the main controller 210 into an analog current signal, using 18-bit and above high-resolution conversion devices. The linear amplification module 240 amplifies the power of the analog current signal to drive the stator winding of the nanopositioning platform, and uses the PA12 device of the linear amplification module to amplify.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (6)

1. A large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform, including a positioning platform mechanical body and a positioning platform controller, is characterized in that the positioning platform mechanical body includes an electromagnetic drive actuator, an air-floating guide mechanism and Eddy current damper module; Wherein, the electromagnetic drive actuator is configured to generate electromagnetic force to realize the change of platform displacement; the air bearing guide mechanism is configured to make the platform move in only one direction; the eddy current damper module is configured to generate damping force to shorten the positioning time of the positioning platform; the eddy current damping module is composed of a copper plate and a winding, the copper plate is fixed on the mover of the positioning platform, and moves with the positioning platform; the winding is wound on the silicon steel sheet, and the two windings form a closed The magnetic field; at the same speed, the magnitude of the current in the control winding is configured to control the strength of the magnetic field, thereby controlling the magnitude of the damping force; Wherein, the air flotation guiding mechanism includes marble guide rails, a first air flotation module, a second air flotation module, a third air flotation module, a fourth air flotation module and a fifth air flotation module; the first air flotation module, The second air flotation module, the third air flotation module, the fourth air flotation module and the fifth air flotation module adopt porous vacuum preloaded air bearings; the first air flotation module, The second air flotation module and the third air flotation module are arranged in a triangle; the first air flotation module is configured to limit the degree of freedom in the vertical direction of the positioning platform, and the second air flotation module is configured to limit The degree of freedom in the pitch direction of the positioning platform, the third air-floating module is configured to limit the degree of freedom in the yaw direction of the positioning platform, the fourth air-floating module is configured to limit the degree of freedom in the horizontal direction of the positioning platform, and the first The five air flotation modules are configured to limit the degrees of freedom in the yaw direction of the positioning platform. 2. A large-stroke single-degree-of-freedom air-floating magnetically driven nanopositioning platform according to claim 1, wherein the electromagnetic drive actuator is composed of a stator and a mover, and the stator is composed of three-phase winding copper The electric phase difference of each phase winding is 120 degrees, and adopts an ironless structure; the mover is composed of a magnetic array, and the arrangement of the magnetic array is configured to ensure that the magnetic field strength is strong on the side facing the winding , the magnetic field strength is weak on the side facing away from the winding; the phase and magnitude of the energized current of the three-phase winding of the stator are configured to change the magnitude of the single-degree-of-freedom direction thrust of the positioning platform. 3. A large-stroke single-degree-of-freedom air-floating magnetically driven nano-positioning platform according to claim 1, wherein the positioning platform controller is controlled by a linear drive circuit, including a main controller, an A/D conversion circuit, a D/A conversion circuit, a linear amplification module, a current sensor and a position sensor; the main controller is configured to run a control algorithm and a positioning platform driving algorithm; the A/D conversion circuit is configured to control the current sensor The output current signal is sampled to complete the current loop control of the positioning platform; the D/A conversion circuit is configured to convert the digital current signal output by the main controller into an analog current signal; the linear amplification module is configured to The analog current signal is amplified to drive the stator winding; the current sensor is configured to collect the stator current signal; the position sensor is configured to collect the position of the mover of the positioning platform. 4. A large-stroke single-degree-of-freedom air-floating magnetically driven nanopositioning platform according to claim 2, wherein the frame of the stator is made of aluminum alloy. 5. A kind of large-stroke single-degree-of-freedom air-floating magnetically driven nanopositioning platform according to claim 2, wherein the magnetic array is bonded to the frame of the stator. 6 . The large-stroke single-degree-of-freedom air-bearing magnetically driven nanopositioning platform according to claim 2 , wherein the magnetic array formed by four magnet blocks is configured to form an electrical cycle.