Ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage and driving method

Abstract

The present invention provides an ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage and a driving method thereof, which includes an electromagnetic driving unit, a base unit, and a piezoelectric driving unit. The piezoelectric driving unit includes a connecting plate, a preloading spring piece, a flexible mechanism, a piezoelectric stack, and a friction rod. The present invention can achieve two working modes of rapid driving and precise positioning through the control of input electrical signals of the electromagnetic driving unit and the piezoelectric driving unit. When the rapid driving mode is executed, the control electrical signal makes the resultant force received by the slider always greater than 0, and the electromagnetic driving unit applies a large DC voltage so that the slider obtains a large resultant force. When the precise positioning mode is executed, the electrical signal of the electromagnetic driving unit is controlled so that the resultant force received by the slider is 0 when the voltage of the piezoelectric driving unit rapidly increases, so as to suppress the displacement retraction generated when the piezoelectric driving unit independently displaces in this stage, and a periodic sawtooth wave is applied to the piezoelectric driving to achieve micro-feeding.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision machinery and high-speed drive, and particularly relates to an ultra-large load stacked friction type piezoelectric electromagnetic hybrid micro-nano stage and a driving method thereof. Background Art

[0002] Piezoelectric actuators have the advantages of high resolution, fast response speed, no electromagnetic interference, and self-locking after power-off, and have become a research hotspot in the field of engineering technology. Piezoelectric actuators have been developed for applications such as micro-robots, biomedicine, mechanical measurement, precision positioning, and 3D printing. At present, piezoelectric precision positioning systems can be classified into direct drive type, piezoelectric inertial drive type, ultrasonic drive type, and inchworm stepping drive type according to their working principles. The direct drive type piezoelectric drive system has a limited stroke and is difficult to achieve millimeter-level displacement. The ultrasonic drive type has a low positioning accuracy, and the problems of friction and heat generation are severe. The inchworm stepping drive type requires at least 3 piezoelectric units to achieve one-degree-of-freedom drive. Piezoelectric inertial actuators have the advantage of simple mechanism, and can achieve one-degree-of-freedom drive through a single piezoelectric element and excitation signal.

[0003] At present, piezoelectric inertial actuators can be classified into inertial impact type piezoelectric actuators and friction drive type piezoelectric inertial actuators. Among them, the friction drive type piezoelectric inertial actuator can achieve self-locking after power-off, but faces a relatively serious displacement retraction problem, which will limit its application in some special working conditions, deteriorate the driving speed, and the serrated displacement will also increase the design difficulty of the control system and the overall positioning accuracy. In addition, piezoelectric actuators based on the piezoelectric inertial drive principle face the problems of weak load capacity and difficulty in achieving high-speed drive when the load is large. Summary of the Invention

[0004] Aiming at the problems of displacement retraction, low horizontal load and vertical load faced by the friction type piezoelectric inertial actuator, the present invention proposes an ultra-large load stacked friction type piezoelectric electromagnetic composite precision drive platform and a driving method thereof. The present invention can suppress displacement retraction and improve the horizontal load and vertical load of the drive platform. By introducing an electromagnetic drive unit, the problems of slow driving speed and weak load capacity caused by a single piezoelectric drive unit are solved by using electromagnetic driving force. During the precision positioning stage, the electromagnetic driving force is used to balance the sliding friction generated by the piezoelectric drive unit during the sliding stage to suppress displacement retraction, improve the smoothness of the displacement curve, improve the positioning accuracy of the drive platform, and broaden the application range of the drive platform.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention first provides an ultra-large load stacked friction piezoelectric electromagnetic hybrid micro-nano stage, which includes an electromagnetic drive unit, a base unit, and a piezoelectric drive unit; the base unit is composed of a horizontal pedestal and a coil assembly mounting boss located on one side of the upper surface of the horizontal pedestal, and is an overall L-shaped structure. Two mutually parallel guide rail assemblies are arranged on the horizontal pedestal of the base unit. The guide rail assembly is composed of a guide rail and a slider arranged on the guide rail and capable of sliding along the guide rail;

[0007] The electromagnetic drive unit is a rectangular voice coil motor, which includes a coil assembly and a magnet assembly; the coil assembly is sleeved inside the magnet assembly. Both the coil assembly and the magnet assembly are rectangular structures, and the central planes in the vertical direction of the two are the same plane; one end of the coil assembly extending out of the magnet assembly is fixedly connected to the coil assembly mounting boss of the base unit, and the magnet assembly is fixedly connected to the two sliders and can move synchronously with the sliders;

[0008] The piezoelectric drive unit includes a connecting plate, a preloading spring piece, a flexible mechanism, a piezoelectric stack, and a friction rod; the connecting plate is respectively fixedly connected to the sliders of the two guide rail assemblies; the flexible mechanism is fixedly installed on the horizontal pedestal of the base unit. The flexible mechanism is hollow and a piezoelectric stack is arranged in the hollow area. One end of the friction rod is fixedly connected to the flexible mechanism, and the other end is suspended. The suspended end is limited by the connecting plate and the preloading spring piece. Among them, the lower surface of the suspended end is in frictional contact with the connecting plate, and the upper surface is in frictional contact with the preloading spring piece. The connecting plate and the preloading spring piece can slide freely relative to the friction rod;

[0009] The friction rod, the guide rail, and the coil assembly are all horizontally installed, and the friction rod is parallel to the two guide rails; the vibration direction of the piezoelectric stack is parallel to the movement direction of the slider.

[0010] The present invention also provides a driving method for the ultra-large load stacked friction piezoelectric electromagnetic hybrid micro-nano stage described above:

[0011] It is stipulated that the rightward movement is the positive direction; during forward driving, a positive direct current is applied to the electromagnetic drive unit. Since the coil assembly is fixed on the base unit, the leftward force F C received by it will be offset by the reaction force of the base unit, and the magnet assembly will receive a rightward force F m , and drive the slider to have a tendency to move rightward; at this time, a sawtooth wave with a duty cycle of 0% to 10% is applied to the piezoelectric drive unit; when the voltage rises rapidly, the piezoelectric stack elongates rapidly and drives the flexible mechanism to deform and the friction rod to elongate rapidly. At this time, since the total friction force between the friction rod and the connecting plate and the preloading spring piece is less than the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod, the friction state is dynamic friction, and the generated friction force is F p2, the direction is to the left; when the voltage slowly decreases, the piezoelectric stack slowly contracts, driving the flexible mechanism to recover its deformation and the friction rod to slowly contract. At this time, the total friction force between the friction rod and the connecting plate and the pre-compressed spring piece can satisfy the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod. Therefore, the friction state is static friction, and the generated friction force is F p1 , the direction is to the right; the friction force between the slider and the guide rail is calibrated with F f . When the voltage rapidly increases, the resultant force F T received by the slider is equal to F m - F P2 - F f ; when the voltage slowly decreases, the resultant force received by the slider is F T = F m + F P1 - F f ; by controlling the electrical signal between the electromagnetic drive unit and the piezoelectric drive unit, the forward drive of the composite positioning stage can be realized, and two modes can be executed, namely the fast drive mode and the precision positioning mode; when the fast drive mode is executed, the control electrical signal makes the resultant force received by the slider always greater than 0, and the electromagnetic drive unit applies a large DC voltage so that the slider obtains a large resultant force F T ; when the precision positioning mode is executed, the control electrical signal of the electromagnetic drive unit is such that the resultant force received by the slider is 0 when the voltage of the piezoelectric drive unit rapidly increases, so as to suppress the displacement backlash generated during the independent displacement of the piezoelectric drive unit in this stage, and a periodic sawtooth wave is applied to the piezoelectric drive to achieve micro-feed;

[0012] When working in the reverse direction, a reverse direct current is applied to the electromagnetic drive unit. At this time, the magnet unit receives a force F m to the left and drives the slider to have a tendency to move to the left; a sawtooth wave voltage signal of 90% - 100% is applied to the piezoelectric drive unit. When the voltage slowly increases, the resultant force received by the slider is F T = F m + F P1 - F f , and when the voltage rapidly decreases, the resultant force received by the slider is F T = F m - F P2 - F f , where, due to the application of the asymmetric excitation signal, there is F p1 > F p2 ; two working modes of fast drive and precision positioning can also be realized during reverse drive.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] Traditional piezoelectric inertial drivers adopt the friction drive principle. Since it is necessary to control the two different friction states of stick-slip generated between the friction pairs of the driver, this limits the maximum static friction force and cannot be too large. Therefore, the horizontal and vertical load capacities are limited. In the present invention, by introducing an electromagnetic drive unit, the problems of slow driving speed and weak load capacity caused by a single piezoelectric drive unit are improved with electromagnetic driving force. During the precision positioning stage, the electromagnetic driving force is used to balance the sliding friction force generated by the piezoelectric drive unit during the sliding stage to suppress displacement retraction, improve the smoothness of the displacement curve, improve the positioning accuracy of the driving platform, and broaden the application range of the driving platform. The present invention has great application prospects in the fields of active optics, sample movement in super-resolution imaging, micro-nano assembly and manufacturing, integrated circuit manufacturing and detection, scanning electron microscope sample manipulation, large-range electron beam direct writing, fiber and nano-CT, high-vacuum sample precision alignment and attitude adjustment, nano-focusing and scanning, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of an ultra-large load stacked friction-type piezoelectric and electromagnetic composite precision driving platform;

[0016] Figure 2 It is an exploded view of the structure of an ultra-large load stacked friction-type piezoelectric and electromagnetic composite precision driving platform;

[0017] Figure 3 It is a schematic diagram of the structure of the electromagnetic drive unit of the present invention;

[0018] Figure 4 It is a schematic diagram of the structure of the base unit of the present invention;

[0019] Figure 5 It is a schematic diagram of the structure of the base of the present invention;

[0020] Figure 6 It is the guide rail assembly of the present invention;

[0021] Figure 7 It is a schematic diagram of the structure of the encapsulation side cover of the present invention;

[0022] Figure 8 It is a schematic diagram of the structure of the piezoelectric drive unit of the present invention;

[0023] Figure 9 It is a schematic diagram of the structure of the connecting plate of the present invention;

[0024] Figure 10 It is a schematic diagram of the structure of the preloading spring piece of the present invention;

[0025] Figure 11 It is a schematic diagram of the flexible mechanism of the present invention;

[0026] Figure 12 It is a working principle diagram of a piezoelectric inertial micro-nano drive platform with an I-shaped flexible mechanism.

[0027] In the figure, there are an electromagnetic driving unit 1, a base unit 2, a piezoelectric driving unit 3, a coil assembly 1-1, a magnet assembly 1-2, a base 2-1, a guide rail assembly 2-2, a packaging side cover 2-3, a coil assembly mounting boss 2-1-1, a coil assembly mounting threaded hole 2-1-2, a packaging top plate 2-1-3, a packaging side plate 2-1-4, a packaging side cover assembly surface 2-1-5, a packaging side cover mounting threaded hole 2-1-6, a flexible mechanism mounting threaded hole 2-1-7, a base bottom plate 2-1-8, a guide rail mounting threaded hole 2-1-9, a chamfer Ⅰ 2-1-10, a guide rail limiting boss 2-1-11, a chamfer Ⅱ 2-1-12, a chamfer Ⅲ 2-1-13, a guide rail limiting surface 2-1-14, a slider 2-2-1, a guide rail 2-2-2, a piezoelectric driving unit assembly groove 2-2-3, a packaging side cover assembly counterbore 2-3-1, a pre-tightening adjustment avoidance through hole 2-3-2, an assembly avoidance groove 2-3-3, a connecting plate 3-1, a pre-compression spring piece 3-2, a flexible mechanism 3-3, a Kimi screw 3-4, a piezoelectric stack 3-5, a friction rod 3-6, a connecting boss 3-1-1, a connecting plate base 3-1-2, an arc-shaped friction plate 3-1-3, a spring piece mounting threaded hole 3-1-4, a spring piece side plate 3-2-1, a spring piece arc-shaped friction plate 3-2-2, a spring piece mounting through hole 3-2-3, a flexible mechanism arc-shaped side beam 3-3-1, a flexible mechanism front straight beam 3-3-2, a flexible mechanism fixing plate 3-3-3, a flexible mechanism fixing through hole 3-3-4, a Kimi screw mounting threaded hole 3-3-5. Specific embodiments

[0028] The present invention will be further described and explained below in conjunction with specific embodiments. The embodiments are only illustrative of the present disclosure and do not delimit the scope of limitation. The technical features of each embodiment of the present invention can be combined accordingly without conflict.

[0029] The overall schematic diagram of the ultra-large load stacked friction piezoelectric electromagnetic force composite precision driving platform designed by the present invention is as Figure 1 shown, and the exploded view of the ultra-large load stacked friction piezoelectric electromagnetic force composite precision driving platform is as Figure 2 shown, which mainly includes an electromagnetic driving unit 1, a base unit 2, and a piezoelectric driving unit 3. Among them, the base unit is composed of a horizontal pedestal and a coil assembly mounting boss located on one side of the upper surface of the horizontal pedestal, and the base unit is of an overall L-shaped structure. The electromagnetic driving unit is a general large-thrust rectangular voice coil motor on the market, with good interchangeability, and it includes a coil assembly 1-1 and a magnet assembly 1-2. The coil assembly 1-1 is sleeved inside the magnet assembly 1-2. Both the coil assembly 1-1 and the magnet assembly 1-2 are of rectangular structures, and the central planes in the vertical direction of the two are the same plane. The magnet assembly 1-2 serves as the load mounting surface.

[0030] AsFigure 4 As shown, two mutually parallel guide rail assemblies are provided on the horizontal pedestal of the pedestal unit. The guide rail assembly is composed of a guide rail 2-2-2 and a slider 2-2-1 arranged on the guide rail and capable of sliding along the guide rail; one end of the coil assembly extending out of the magnet assembly is fixedly connected to the coil assembly mounting boss of the pedestal unit, and the magnet assembly is fixedly connected to the two sliders and can move synchronously with the sliders.

[0031] The pedestal unit of the present invention mainly serves as the installation foundation for each component and provides a guide rail assembly so that some components thereon can achieve sliding. As Figure 2-7 shown, in an embodiment of the present invention, the pedestal unit 2 includes a pedestal 2-1, a guide rail assembly 2-2 and a packaging side cover 2-3.

[0032] As Figure 5 shown, the pedestal 2-1 is provided with a coil assembly mounting boss 2-1-1, a coil assembly mounting threaded hole 2-1-2, a packaging top plate 2-1-3, a packaging side plate 2-1-4, a packaging side cover assembly surface 2-1-5, a packaging side cover mounting threaded hole 2-1-6, a flexible mechanism mounting threaded hole 2-1-7, a pedestal bottom plate 2-1-8, a guide rail mounting threaded hole 2-1-9, a chamfer Ⅰ 2-1-10, a guide rail limiting boss 2-1-11, a chamfer Ⅱ 2-1-12, a chamfer Ⅲ 2-1-13 and a guide rail limiting surface 2-1-14; as Figure 6 shown, the guide rail assembly 2-2 includes a slider 2-2-1 and a guide rail 2-2-2, wherein the slider 2-2-1 is provided with a piezoelectric drive unit assembly groove 2-2-3; as Figure 7 shown, the packaging side cover 2-3 is provided with a packaging side cover assembly countersunk hole 2-3-1, a pre-tightening adjustment avoidance through hole 2-3-2 and an assembly avoidance groove 2-3-3.

[0033] In the pedestal unit 2, the two guide rails 2-2-2 are in contact with the pedestal bottom plate 2-1-8. Among them, the guide rail 2-2-2 installation through holes and the four guide rail installation threaded holes 2-1-9 evenly distributed on the pedestal bottom plate 2-1-8 are concentrically aligned. The guide rail limiting boss 2-1-11 and the guide rail limiting surface 2-1-14 are used for limiting during the assembly of the guide rail to facilitate installation. Screws are connected through the guide rail 2-2-2 installation through holes and screwed into the guide rail installation threaded holes 2-1-9 to fix the two guide rails 2-2-2 on the pedestal 2-1. The two sliders 2-2-1 and the two guide rails 2-2-2 adopt groove fit, and the slider is not in contact with the pedestal bottom plate 2-1-8 and the guide rail limiting boss 2-1-11.

[0034] On both sides of the coil assembly mounting boss 2-1-1, U-shaped openings are formed with two encapsulation side plates 2-1-4 and vertically distributed above the base bottom plate 2-1-8. The encapsulation top plate 2-1-3 is fixedly connected to the coil assembly mounting boss 2-1-1 and the two encapsulation side plates 2-1-4. The chamfers I 2-1-10, chamfers II 2-1-12 and chamfers III 2-1-13 are provided to avoid stress concentration and reduce the processing difficulty, and the above chamfers do not cause assembly and movement interference with the guide rail assembly 2-2 during installation; the flexible mechanism mounting threaded holes 2-1-7 are used for fixing the piezoelectric drive unit 3; in the middle and lower part of the encapsulation side cover 2-3, an assembly avoidance groove 2-3-3 is provided to reserve part of the space required for the installation of the piezoelectric drive unit 3. At both ends of the upper part, two encapsulation side cover assembly counterbore holes 2-3-1 are evenly distributed, and a pre-tightening adjustment avoidance through hole 2-3-2 is provided in the middle to provide an operating space for the wrench during the pre-tightening force adjustment of the piezoelectric drive unit 3; the two encapsulation side cover assembly counterbore holes 2-3-1 are concentric with the guide rail mounting threaded holes 2-1-9, and the encapsulation side cover assembly surface 2-1-5 is used for limiting during the assembly of the encapsulation side cover 2-3. Two screws are passed through the encapsulation side cover assembly counterbore holes 2-3-1 and screwed into the guide rail mounting threaded holes 2-1-9 to fix the encapsulation side cover 2-3 on the base 2-1; four screws are passed through the through holes on the magnet assembly 1-2 and screwed into the threaded holes on the slider 2-2-1 of the magnet assembly 1-2 to fix the magnet assembly 1-2 on the slider; four screws are passed through the through holes on the coil assembly 1-1 and screwed into the coil assembly mounting threaded holes 2-1-2 to fix the coil assembly 1-1 on the coil assembly mounting boss 2-1-1 of the base 2-1; the magnet assembly 1-2 can move freely with the slider 2-2-1, and the guide rail limiting surface 2-1-14 and the inner wall of the assembly avoidance groove 2-3-3 limit the slider.

[0035] As Figure 8-11 shown, in an embodiment of the present invention, the piezoelectric drive unit 3 is composed of a connecting plate 3-1, a preloading spring piece 3-2, a flexible mechanism 3-3, a piezoelectric stack 3-5 and a friction rod 3-6. As Figure 9 shown, the connecting plate 3-1 is provided with a connecting boss 3-1-1, a connecting plate base 3-1-2, an arc-shaped friction plate 3-1-3 and a spring piece mounting threaded hole 3-1-4; two connecting plate bases 3-1-2 are connected to both sides of the arc-shaped friction plate 3-1-3, two spring piece mounting threaded holes 3-1-4 are evenly distributed on the two connecting plate bases 3-1-2, and two connecting bosses 3-1-1 are arranged left and right.

[0036] As Figure 10As shown, the preloading spring piece 3-2 is composed of a spring piece arc friction plate 3-2-2 and two spring piece side plates 3-2-1 arranged on both sides thereof. A spring piece mounting through hole 3-2-3 is provided on the spring piece side plate 3-2-1. The material of the preloading spring piece 3-2 is spring steel, which has good elasticity.

[0037] As Figure 11 As shown, the flexible mechanism 3-3 is a middle hollow structure surrounded by two flexible mechanism arc side beams 3-3-1, a flexible mechanism front straight beam 3-3-2, and a flexible mechanism fixing plate 3-3-3. Among them, two flexible mechanism fixing through holes 3-3-4 are provided at both ends of the flexible mechanism fixing plate 3-3-3, and a Gimmi screw mounting threaded hole 3-3-5 is provided in the middle of the side surface. The piezoelectric stack 3-5 is placed at the center of the hollow structure of the flexible mechanism 3-3, with one end abutted on the flexible mechanism front straight beam 3-3-2. The Gimmi screw 3-4 is screwed into the Gimmi screw mounting threaded hole 3-3-5 and abutted against the other end of the piezoelectric stack 3-5 to fix the piezoelectric stack 3-5 in the flexible mechanism 3-3. One end of the friction rod 3-6 is fixedly connected to the flexible mechanism front straight beam 3-3-2, and the other end is suspended. The preloading spring piece 3-2 and the connecting plate 3-1 clamp the friction rod 3-6 in the center. Among them, the arc friction plate 3-1-3 and the spring piece arc friction plate 3-2-2 limit the friction rod 3-6. The spring piece mounting threaded hole 3-1-4 and the spring piece mounting through hole 3-2-3 are concentrically aligned. Screws are passed through the spring piece mounting threaded hole 3-1-4 and screwed into the spring piece mounting through hole 3-2-3 to connect the three. The friction rod 3-6 is in frictional contact with the connecting plate 3-1 and the preloading spring piece 3-2. When overcoming the frictional force between the three, the connecting plate 3-1 and the preloading spring piece 3-2 can slide freely relative to the friction rod 3-6. The material of the friction rod 3-6 can be wear-resistant materials such as carbon fiber rods or bearing steel. Screws are passed through the flexible mechanism fixing through holes 3-3-4 and screwed into the flexible mechanism mounting threaded hole 2-1-7 to fixedly connect the flexible mechanism 3-3 to the base 2-1. The connecting boss 3-1-1 is embedded in the piezoelectric drive unit assembly groove 2-2-3, and the two are in interference fit, which can achieve better driving force transmission.

[0038] In the present invention, the friction rod, the guide rail, and the coil assembly are all horizontally installed. The moving directions of the connecting plate 3-1, the preloading spring piece 3-2, the slider, and the magnet unit are parallel to each other, and are all horizontally to the left or right. The vibration direction of the piezoelectric stack is parallel to the above-mentioned moving direction.

[0039] The working principle of the super-large load stacked friction type piezoelectric electromagnetic composite precision drive platform of the present invention is as Figure 12 shown, where the rightward movement is defined as the positive direction. During forward driving, a positive direct current is applied to the electromagnetic drive unit, and its current direction is as Figure 12As shown in (a), according to Faraday's law of electromagnetic induction, the force conditions of the coil assembly and the magnet assembly can be known. Since the coil assembly is fixed on the base, the leftward force F it receives C will be offset by the reaction force of the base, and the magnet assembly will receive a rightward force F m , and drive the slider to have a tendency to move to the right; at this time, a sawtooth wave with a duty cycle of 0% - 10% can be applied to the piezoelectric drive unit. In the present invention, a cycle of the sawtooth wave consists of two time periods: a voltage rising section and a voltage falling section. The duty cycle of a% means that in a cycle of the sawtooth wave, the duration of the voltage rising section accounts for a% of the cycle time. Among them, the final voltage of the voltage rising section (falling section) is the initial voltage of the voltage falling section (rising section), the voltage rising rate of the voltage rising section is constant, and the voltage decreasing rate of the voltage falling section is also constant.

[0040] When the voltage rises rapidly, the piezoelectric stack elongates rapidly and drives the flexible mechanism to deform and the friction rod to elongate rapidly. At this time, since the total friction force between the friction rod and the connecting plate and the preloading spring piece is less than the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod, the friction state is dynamic friction, and the generated friction force is F p2 , in the leftward direction; when the voltage decreases slowly, the piezoelectric stack contracts slowly and drives the flexible mechanism to recover deformation and the friction rod to contract slowly. At this time, the total friction force between the friction rod and the connecting plate and the preloading spring piece can satisfy the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod, so the friction state is static friction, and the generated friction force is F p1 , in the rightward direction; calibrate the friction force between the slider and the guide rail with F f . When the voltage rises rapidly, the resultant force F T received by the slider = F m - F P2 - F f ; when the voltage decreases slowly, the resultant force received by the slider is F T = F m + F P1 - F f . By controlling the electrical signals between the electromagnetic drive unit and the piezoelectric drive unit, the forward drive of the composite positioning table can be realized, and two modes can be executed, namely the fast drive mode and the precision positioning mode; when executing the fast drive mode, the control electrical signal makes the resultant force received by the slider always greater than 0, and the electromagnetic drive unit applies a large DC voltage so that the slider obtains a large resultant force F T ; when executing the precision positioning mode, control the electrical signal of the electromagnetic drive unit so that the resultant force of the slider is 0 when the voltage of the piezoelectric drive unit rises rapidly, in order to suppress the displacement regression generated when the piezoelectric drive unit displaces independently in this stage, and apply a periodic sawtooth wave to the piezoelectric drive to achieve micro-feeding.

[0041] The reverse working principle is as shown in Figure 12 b in the figure. When a reverse direct current is applied to the electromagnetic drive unit, it can be known from the force analysis that the magnet unit is subjected to a force F to the left m . And it drives the slider to have a tendency to move to the left. When a sawtooth voltage signal of 90% - 100% is applied to the piezoelectric drive unit, when the voltage slowly rises, the resultant force on the slider is F T = F m + F P1 - F f . When the voltage rapidly decreases, the resultant force on the slider is F T = F m - F P2 - F f . Among them, due to the application of the asymmetric excitation signal, there is F p1 > F p2 . Similar to the forward working principle, two working modes of fast driving and precise positioning can also be realized during reverse driving.

[0042] The friction piezoelectric inertial drive platform has advantages such as power-off self-locking and high positioning accuracy, but it faces problems such as displacement retraction and low horizontal and vertical loads. The present invention proposes a super-large load stacked friction piezoelectric electromagnetic composite precision drive platform and a drive method to suppress displacement retraction and improve the horizontal and vertical loads of the drive platform. By introducing an electromagnetic drive unit, the problems of slow driving speed and weak load capacity caused by a single piezoelectric drive unit are solved by using electromagnetic driving force. During the precise positioning stage, the electromagnetic driving force is used to balance the sliding friction generated by the piezoelectric drive unit during the sliding stage to suppress displacement retraction, improve the smoothness of the displacement curve, improve the positioning accuracy of the drive platform, and broaden the application range of the drive platform. The present invention has great application prospects in the fields of active optics, super-resolution imaging sample movement, micro-nano assembly and manufacturing, integrated circuit manufacturing and detection, scanning electron microscope sample manipulation, large-range electron beam direct writing, fiber and nano-CT, high-vacuum sample precision alignment and attitude adjustment, nano-focusing and scanning, etc.

[0043] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present invention. For those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage, characterized in that, It includes an electromagnetic drive unit (1), a base unit (2) and a piezoelectric drive unit (3); the base unit consists of a horizontal pedestal and a coil assembly mounting boss located on one side of the upper surface of the horizontal pedestal, and is of an overall L-shaped structure. Two mutually parallel guide rail assemblies are provided on the horizontal pedestal of the base unit. The guide rail assembly is composed of a guide rail (2-2-2) and a slider (2-2-1) arranged on the guide rail and capable of sliding along the guide rail. The electromagnetic drive unit is a rectangular voice coil motor, which includes a coil assembly (1-1) and a magnet assembly (1-2); the coil assembly is sleeved inside the magnet assembly. Both the coil assembly and the magnet assembly are of rectangular structures, and the central planes in the vertical direction of the two are the same plane; one end of the coil assembly extending out of the magnet assembly is fixedly connected to the coil assembly mounting boss of the base unit, and the magnet assembly is fixedly connected to the two sliders and can move synchronously with the sliders. The piezoelectric drive unit includes a connecting plate (3-1), a preloading spring piece (3-2), a flexible mechanism (3-3), a piezoelectric stack (3-5) and a friction rod (3-6); the connecting plate (3-1) is fixedly connected to the sliders of the two guide rail assemblies respectively; the flexible mechanism (3-3) is fixedly installed on the horizontal pedestal of the base unit. The flexible mechanism (3-3) is hollow inside and a piezoelectric stack (3-5) is arranged in the hollow area. One end of the friction rod (3-6) is fixedly connected to the flexible mechanism (3-3), and the other end is suspended. The suspended end is limited by the connecting plate (3-1) and the preloading spring piece (3-2). Among them, the lower surface of the suspended end is in frictional contact with the connecting plate, and the upper surface is in frictional contact with the preloading spring piece. The connecting plate and the preloading spring piece can slide freely relative to the friction rod. The friction rod, the guide rail and the coil assembly are all horizontally installed, and the friction rod is parallel to the two guide rails; the vibration direction of the piezoelectric stack is parallel to the movement direction of the slider. The driving method of the ultra-large load stacked friction type piezoelectric electromagnetic hybrid micro-nano stage is as follows: It is stipulated that the rightward movement is the positive direction; when driving in the positive direction, a positive direct current is applied to the electromagnetic drive unit. Since the coil assembly is fixed on the base unit, the force acting on it to the left F C will be offset by the reaction force of the base unit, and the magnet assembly will be subjected to a force to the right F m , and drive the slider to have a tendency to move to the right; at this time, a sawtooth wave with a duty cycle of 0% - 10% is applied to the piezoelectric drive unit; when the voltage rises rapidly, the piezoelectric stack elongates rapidly and drives the flexible mechanism to deform and the friction rod to elongate rapidly. At this time, since the total friction force between the friction rod and the connecting plate and the preloaded spring piece is less than the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod, the friction state is dynamic friction, and the generated friction force is F p2 , in the leftward direction; when the voltage drops slowly, the piezoelectric stack contracts slowly and drives the flexible mechanism to recover deformation and the friction rod to contract slowly. At this time, the total friction force between the friction rod and the connecting plate and the preloaded spring piece can satisfy the driving force required for the magnet assembly and the slider to generate the same speed as the friction rod, so the friction state is static friction, and the generated friction force is F p1 , in the rightward direction; the friction force between the slider and the guide rail is calibrated with F f . When the voltage rises rapidly, the resultant force on the slider F T = F m -F P2 - F f ; when the voltage drops slowly, the resultant force on the slider is F T = F m + F P1 - F f ; by controlling the electrical signals between the electromagnetic drive unit and the piezoelectric drive unit, the forward drive of the composite positioning table can be realized, and two modes can be executed, namely the fast drive mode and the precision positioning mode; when executing the fast drive mode, the control electrical signal makes the resultant force on the slider always greater than 0; when executing the precision positioning mode, the electrical signal of the electromagnetic drive unit is controlled so that the resultant force on the slider is 0 when the voltage of the piezoelectric drive unit rises rapidly, so as to suppress the displacement back-off generated during the independent displacement of the piezoelectric drive unit in this stage, and a periodic sawtooth wave is applied to the piezoelectric drive to achieve micro-feed; When working in the reverse direction, a reverse direct current is applied to the electromagnetic drive unit. At this time, the magnet unit is subjected to a force to the left F m , and it drives the slider to have a tendency to move to the left; a sawtooth wave voltage signal of 90% - 100% is applied to the piezoelectric drive unit. When the voltage slowly rises, the resultant force on the slider is F T = F m + F P1 - F f . When the voltage rapidly decreases, the resultant force on the slider is F T = F m - F P2 - F f , where, due to the application of the asymmetric excitation signal, there is F p1 >F p2 ; two working modes of fast driving and precise positioning can also be achieved during reverse driving.

2. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 1, characterized in that, The flexible mechanism is an intermediate hollow structure surrounded by two flexible mechanism arc side beams (3-3-1), a flexible mechanism front straight beam (3-3-2), and a flexible mechanism fixing plate (3-3-3); among them, two flexible mechanism fixing through holes (3-3-4) are opened at both ends of the flexible mechanism fixing plate (3-3-3), and a Kimi screw installation threaded hole (3-3-5) is opened in the middle of the side surface; the piezoelectric stack (3-5) is placed at the center of the hollow structure of the flexible mechanism (3-3), and one end abuts against the flexible mechanism front straight beam (3-3-2). A Kimi screw (3-4) is screwed into the Kimi screw installation threaded hole (3-3-5) and abuts against the other end of the piezoelectric stack (3-5) to fix the piezoelectric stack (3-5) in the flexible mechanism (3-3).

3. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 1, characterized in that, The connecting plate (3-1) is provided with a connecting boss (3-1-1), a connecting plate substrate (3-1-2), an arc friction plate (3-1-3) and a reed mounting threaded hole (3-1-4); two connecting plate substrates are connected to both sides of the arc friction plate, two reed mounting threaded holes are evenly distributed on the two connecting plate substrates, and two connecting bosses are arranged on each connecting plate substrate; the preloading reed (3-2) is composed of a reed arc friction plate (3-2-2) and two reed side plates (3-2-1) arranged on both sides thereof, wherein a reed mounting through hole (3-2-3) is formed on the reed side plate (3-2-1), the preloading reed and the connecting plate clamp the suspended end of the friction rod in the center, the reed mounting threaded hole and the reed mounting through hole are concentrically aligned, and the three are connected by screwing a screw through the reed mounting threaded hole and into the reed mounting through hole.

4. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 3, characterized in that, Each of the connecting plate substrates is fixedly connected to a slider through two connecting bosses thereon, and the two sliders and the connecting plate are connected to each other as a whole and move synchronously.

5. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 1, characterized in that, The material of the preloading reed is spring steel, and the material of the friction rod is carbon fiber rod or bearing steel.

6. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 1, characterized in that, The slider and the guide rail adopt a type groove fit, and limiting devices are arranged at both ends of the guide rail to restrict the sliding stroke of the slider.

7. The ultra-large load stacked frictional piezoelectric electromagnetic hybrid micro-nano stage according to claim 1, characterized in that, The upper surface of the magnet assembly serves as the mounting surface for the external load.

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