High-precision lifting and leveling integrated platform based on voice coil motor direct drive

Abstract

This invention discloses a high-precision lifting-leveling integrated platform based on direct drive of voice coil motors, comprising a base and a moving platform. Three voice coil motors are arranged circumferentially between the base and the moving platform, with the output direction of each motor set along the Z-axis. The platform is characterized by: three planar flexible hinges, each corresponding to one of the three voice coil motors circumferentially; a stator fixed to the base, and a mover directly contacting the moving platform; the fixed part of each planar flexible hinge is fixedly connected to the base, and the following part is fixedly connected to the moving platform, serving as a parallel support and guiding component that adapts to the deformation of the moving platform synchronously; the stiffness of the planar flexible hinges in the XY plane is greater than their stiffness in the Z direction, used to constrain the horizontal translational displacement of the moving platform while bearing the load, isolating the Z-axis motion and angle leveling from affecting the XY plane positioning. This invention achieves structural-level motion decoupling, improving the long-term accuracy and stability of the platform.

Description

Technical Field

[0001] This invention relates to the field of precision positioning platform technology, specifically to a lifting-leveling integrated positioning platform based on direct drive of a voice coil motor. Background Technology

[0002] In high-end equipment fields such as semiconductor manufacturing, optical inspection, biomedicine, and aerospace, extremely high requirements are placed on the multi-degree-of-freedom collaborative control accuracy, travel range, structural compactness, and operational stability of precision positioning equipment. Among them, the Z-Tip-Tilt integrated platform, which can simultaneously realize vertical lifting (Z-axis) and horizontal leveling (Tip-Tilt, i.e., pitch and yaw) functions, is a core positioning component, and its performance directly determines the process accuracy and operational efficiency of downstream equipment. With the continuous improvement of micro-nano manufacturing and precision inspection process accuracy, the industry has placed increasingly stringent requirements on the comprehensive performance of positioning platforms. They not only need to have sufficient working stroke, but also need to simultaneously meet multiple indicators such as high angular resolution, low inter-axis coupling interference, zero backlash, low nonlinear error, and high attitude stability.

[0003] Currently, the drive solutions for the Z-Tip-Tilt integrated platform mainly fall into three categories: those based on piezoelectric ceramics, servo motors with reducers, and traditional voice coil motors. Each solution has inherent technical limitations, making it difficult to simultaneously meet the comprehensive performance requirements of large stroke, high precision, and low coupling.

[0004] The first category is the piezoelectric ceramic drive scheme. This scheme utilizes the inverse piezoelectric effect of piezoelectric materials to achieve micro-displacement output, featuring high displacement resolution and compact structure. However, its physical characteristics impose significant limitations: First, the effective stroke is extremely small; the conventional working stroke of stacked piezoelectric ceramics is generally less than 200μm, which cannot meet the millimeter-level Z-axis working stroke requirements of most industrial scenarios. Second, piezoelectric stacks require a dedicated pre-tightening mechanism to ensure output stiffness and motion reliability. Pre-tightening parameter debugging is difficult, product consistency is poor, and assembly and manufacturing costs are increased. Third, piezoelectric materials have inherent hysteresis, creep, and temperature drift nonlinear characteristics, resulting in low open-loop control accuracy. Complex compensation algorithms and control models are required, and the compensation effect is limited under high-frequency dynamic leveling conditions, leading to insufficient dynamic response and operational stability.

[0005] The second type is the drive scheme of servo motor combined with reducer. This scheme can achieve a large output load and working stroke, but the power transmission relies on a multi-stage transmission structure such as gears, ball screws, and couplings, which inevitably has meshing backlash, screw backlash, and elastic deformation of components. The transmission chain backlash directly leads to the degradation of the platform's angular resolution. The angular resolution of conventional schemes is generally greater than 10μrad, and there is a significant return dead zone. Under leveling conditions with frequent reversals, the positioning repeatability is poor and errors are easy to accumulate. At the same time, the wear of transmission components increases after long-term operation, which will further expand the backlash, causing the platform's accuracy to continuously decline, and it cannot meet the high-precision leveling requirements at the sub-micro-radian level.

[0006] The third category is a combined drive scheme based on voice coil motors. Voice coil motors operate based on the Lorentz force principle, possessing advantages such as contactless transmission, no hysteresis, fast response speed, and a large stroke range, making them one of the mainstream development directions in the field of precision positioning. However, existing multi-degree-of-freedom voice coil positioning platforms mostly adopt a simple splicing structure of multiple single-degree-of-freedom voice coil motors, which has two core defects: Firstly, when multiple motors are densely arranged, the alternating magnetic fields generated by each coil superimpose and interfere with each other, generating electromagnetic crosstalk. This not only affects the detection signals of high-precision position sensors such as gratings and capacitors, increasing positioning noise, but also changes the thrust coefficient of each motor, causing a decrease in output linearity and leading to interference between Z-axis motion and tip-tilt angular motion, resulting in significant inter-axis coupling errors. Secondly, existing platforms lack suitable decoupling support structures, and the stiffness matching of each motion degree of freedom is unreasonable. Z-axis lifting motion easily causes disturbances to the positioning attitude in the XY directions of the horizontal plane, leading to planar offset and attitude instability during leveling, significantly reducing positioning consistency and multi-axis collaborative control accuracy.

[0007] In summary, the three mainstream drive solutions for existing Z-Tip-Tilt integrated platforms all have their own insurmountable technical defects. The core contradiction lies in the mutual constraints of "stroke-accuracy-complexity": piezoelectric ceramic drives offer high accuracy but insufficient stroke, rely on preload, and exhibit significant nonlinearity; servo motor + reducer drives have strong load capacity but transmission backlash leads to insufficient accuracy; traditional voice coil motors offer good dynamic response but multi-axis integration results in electromagnetic coupling and a loose structure. These defects prevent existing platforms from simultaneously meeting the core requirements of high-end equipment fields for large stroke, high precision, multi-axis decoupling, compact structure, and stable operation. Therefore, further improvements and optimizations to the drive and support structure of Z-Tip-Tilt integrated platforms are still needed in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a high-precision lifting-leveling integrated platform based on voice coil motor direct drive, which increases the adjustment stroke while avoiding the influence of Z-axis displacement on XY positioning and improving adjustment accuracy.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: a high-precision lifting-leveling integrated platform based on direct drive of voice coil motors, including a base and a moving platform disposed above the base. The horizontal plane where the base is located is defined as the XY plane, and the vertical direction perpendicular to the XY plane is defined as the Z direction. Three voice coil motors are arranged circumferentially between the base and the moving platform. The output direction of each voice coil motor is set along the Z axis, which is used to collaboratively drive the moving platform to realize Z-direction lifting motion and pitch and yaw two-dimensional angle leveling motion. The platform also includes three planar flexible hinges, which are arranged one-to-one with the three voice coil motors along the circumferential direction. The stator of the voice coil motor is fixed to the base, and the mover is in direct contact with the moving platform. The Z-axis driving load is directly applied to the moving platform without being transmitted through the planar flexible hinge. The planar flexible hinge has a fixed part and a follower part. The fixed part is fixedly connected to the base, and the follower part is fixedly connected to the moving platform. As a parallel support and guide component, it synchronously adapts to the deformation of the moving platform. The stiffness of the planar flexible hinge in the XY plane is greater than that in the Z direction. It is used to constrain the horizontal translational displacement of the moving platform while bearing the load, and to isolate the interference of Z-direction movement and angle leveling on the positioning of the XY plane.

[0010] In the above technical solution, the Z-axis drive load of the voice coil motor acts directly on the moving platform without being transmitted through the planar flexible hinge, which is fundamentally different from the series transmission mechanism commonly found in existing technologies. The planar flexible hinge only acts as a parallel support component, undergoing flexible deformation with the moving platform to bear the load gravity and guiding constraint force, without participating in the transmission of the main driving force. Therefore, it can effectively reduce the stress level of the hinge and avoid positioning errors introduced by force transmission deformation. The stiffness of the planar flexible hinge in the XY plane is greater than its stiffness in the Z direction. By constraining the horizontal translational degree of freedom of the moving platform with its anisotropic stiffness, it only allows bending deformation and angular deflection in the Z direction, thereby isolating the Z-axis lifting and angular leveling from the interference of XY plane positioning and achieving motion decoupling.

[0011] In the above technical solution, one way to achieve direct contact and cooperation between the mover and the moving platform is that a roller bracket is fixed on the lower surface of the moving platform for each voice coil motor, and a roller is rotatably mounted on the roller bracket. The outer circumferential surface of the roller makes rolling contact with the top surface of the mover of the corresponding voice coil motor, and the Z-direction driving load output by the voice coil motor acts directly on the moving platform through the roller and the roller bracket.

[0012] In a further technical solution, the moving platform has a through mounting hole along the Z direction for each planar flexible hinge, and a ceramic bracket is fixed on the base, with the upper end of the ceramic bracket extending into the corresponding mounting hole; the planar flexible hinge is embedded in the mounting hole, its fixed part is fixedly connected to the upper end of the ceramic bracket, and its follower part is fixedly connected to the moving platform through a roller bracket.

[0013] In a preferred embodiment, the planar flexible hinge is a rectangular sheet structure with multiple slots arranged along a quasi-annular path. These slots separate and form an integrated outer ring fixing part, an inner ring following part, and a flexible deformation area connecting the two.

[0014] In a further technical solution, each voice coil motor is provided with two sets of ceramic supports, which are respectively located on both radial sides of the voice coil motor; the two ends of the outer ring fixing part of the planar flexible hinge are respectively fixed to the top of the two sets of ceramic supports.

[0015] Alternatively, each voice coil motor may be provided with two sets of ceramic supports, which are located on the radial sides of the voice coil motor and connected at the top of the two sets of ceramic supports by a ceramic connecting frame; the two ends of the outer ring fixing part of the planar flexible hinge are fixed on the ceramic connecting frame.

[0016] In the above technical solution, the rotation axis of the roller is set in the horizontal direction. When the moving platform performs angle leveling movement, a small radial relative rolling can be generated between the roller and the moving part of the voice coil motor to compensate for the radial displacement difference during the leveling process and eliminate the lateral additional stress.

[0017] In the above technical solution, the ceramic bracket is made of insulating ceramic material. This is used to isolate heat conduction and electromagnetic interference between the voice coil motor and the moving platform, reducing the impact of motor heating and electromagnetic crosstalk on positioning accuracy.

[0018] In a further technical solution, at least three Z-axis displacement detection units are provided between the base and the moving platform, respectively corresponding to the arrangement positions of the three voice coil motors, for real-time acquisition of the vertical displacement data of the moving platform, and calculation of pitch and yaw angle information.

[0019] In the above technical solution, a limiting structure is provided between the mating surface of the ceramic bracket and the mounting hole to limit the maximum stroke of the moving platform in the Z-direction lifting and angle leveling, and to prevent the planar flexible hinge from undergoing excessive plastic deformation.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. This invention adopts a voice coil motor direct drive structure, with no intermediate transmission gap and hysteresis, and takes into account both millimeter-level large stroke and sub-micro-arc-level high resolution, solving the inherent defects of insufficient stroke of piezoelectric solution and large gap of servo solution. 2. The present invention adopts a planar flexible hinge parallel support structure with three points arranged in a one-to-one correspondence. The hinges only bear the guiding load and do not transmit the main driving force. This reduces the hinge stress and improves the service life. Furthermore, through the anisotropic characteristics of high stiffness in XY and low stiffness in Z, the influence and disturbance of Z-axis motion and angle leveling on the XY plane are isolated, thereby achieving structural motion decoupling. 3. The present invention uses an insulating ceramic bracket as the mounting base, which also has the functions of heat insulation and magnetic shielding, suppressing the impact of motor heating and electromagnetic crosstalk on positioning accuracy, and improving the accuracy and stability of the platform during long-term operation. 4. The roller contact direct drive structure of the present invention can adaptively compensate for the radial displacement difference during the leveling process, eliminate the lateral stress of the motor, and improve the smoothness and reliability of operation. Attached Figure Description

[0021] Figure 1 This is a three-dimensional schematic diagram of the product according to Embodiment 1 of the present invention; Figure 2 This is a top view of the product in Embodiment 1; Figure 3 yes Figure 2 AA section view; Figure 4 yes Figure 2 BB section view; Figure 5 yes Figure 1 A schematic diagram of the removal of the automatic platform in the middle; Figure 6 This is a schematic diagram of a planar flexible hinge.

[0022] The components are: 1. Base; 2. Moving platform; 3. Planar flexible hinge; 4. Flexible deformation zone; 5. Roller; 6. Roller bracket; 7. Ceramic bracket; 8. Ceramic connecting frame; 9. Stator; 10. Mover; 11. Mounting hole; 12. Fixing part; 13. Follower part; 14. First screw; 15. Second screw; 16. Connector; 17. Slot. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: See Figure 1 As shown, a high-precision lifting-leveling integrated platform based on voice coil motor direct drive includes a base 1, a moving platform 2 located above the base, three voice coil motors, and three planar flexible hinges 3. The horizontal plane containing the base 1 is defined as the XY plane, and the vertical direction perpendicular to the XY plane is defined as the Z direction. The three voice coil motors are arranged circumferentially between the base 1 and the moving platform 2, with the output direction of each voice coil motor set along the Z-axis. The three planar flexible hinges 3 are arranged correspondingly to the three voice coil motors along the same pitch circle, forming an equilateral triangle evenly distributed.

[0024] See appendix Figure 3 , Figure 4 and Figure 6As can be seen, on the base, corresponding to each voice coil motor, there are two sets of ceramic supports 7. The two sets of ceramic supports 7 are respectively located on the radial sides of the voice coil motor, and the tops of the two sets of ceramic supports 7 are connected as one unit by a ceramic connecting frame 8.

[0025] Figure 3 In this system, the stator 9 of the voice coil motor is fixed to the base 1. A roller bracket 6 is fixed to the lower surface of the moving platform 2 for each voice coil motor. A roller 5 is rotatably mounted on the roller bracket 6. The outer circumferential surface of the roller 5 rolls in contact with the top surface of the mover 10 of the corresponding voice coil motor. The Z-axis drive load output by the voice coil motor acts directly on the moving platform 2 via the roller 5 and roller bracket 6. The three voice coil motors work together to drive the moving platform to achieve Z-axis lifting and lowering motion, as well as pitch and yaw two-dimensional angle leveling motion.

[0026] See Figure 1 and Figure 2 On the moving platform, each planar flexible hinge 3 has a through-hole 11 along the Z direction. The mounting hole 11 can be positioned directly above the voice coil motor. The upper end of the ceramic bracket 7 on the base 1 extends into the corresponding mounting hole. Since the two sets of ceramic brackets 7 are located on both sides of the voice coil motor, see... Figure 3 and Figure 4 The roller bracket 6 can be located between the two sets of ceramic brackets without affecting the contact between the roller 5 and the voice coil motor mover 10, and the upper end face of the roller bracket 6 can be flush with the upper end face of the ceramic bracket 7; the planar flexible hinge 3 is embedded in the mounting hole 11 and located above the roller bracket 6 and the ceramic bracket 7, see [reference]. Figure 5 The fixing part 12 of the planar flexible hinge 3 is fixedly connected to the upper end face of the ceramic bracket 7. The specific connection method can be as follows: Figure 5 As shown, a connector 16 is added to the ceramic connecting frame 8. The fixing parts 12 on both sides of the planar flexible hinge 3 are fixed to the connector 16 by a first screw 14. The follower part 13 is fixedly connected to the upper end face of the roller bracket 6 by four second screws 15, thereby achieving a fixed connection with the moving platform.

[0027] In this embodiment, as Figure 6 As shown, the planar flexible hinge is a rectangular sheet structure with multiple slots 17 arranged along a quasi-annular path. These slots 17 separate and form an integrated fixed part 12 on the outer ring, a follower part 13 on the inner ring, and a flexible deformation zone 4 connecting the two. Therefore, the stiffness of the planar flexible hinge in the XY plane is greater than its stiffness in the Z direction. This allows it to both bear the load and constrain the horizontal translational displacement of the moving platform, isolating the Z-direction motion and angle leveling from affecting the XY plane positioning.

[0028] In this embodiment, the output thrust of the voice coil motor acts directly on the moving platform. The transmission path of the main driving load is: voice coil motor mover → roller → roller bracket → moving platform. The planar flexible hinge only serves as a parallel support component, undergoing flexible deformation with the moving platform to bear the load gravity and guiding constraint force. It does not participate in the transmission of the main driving force, thus effectively reducing the stress level of the hinge and avoiding positioning errors introduced by force transmission deformation.

[0029] Example 2: A high-precision lifting-leveling integrated platform based on direct drive of voice coil motors. Its basic structure and working principle are the same as those of Example 1, including a base, a moving platform located above the base, three voice coil motors, and three planar flexible hinges. The horizontal plane where the base is located is defined as the XY plane, and the vertical direction perpendicular to the XY plane is defined as the Z direction. The three voice coil motors are arranged circumferentially between the base and the moving platform, and the output direction of each voice coil motor is set along the Z-axis. The three planar flexible hinges and the three voice coil motors are arranged one-to-one along the same pitch circle, forming an equilateral triangle evenly distributed.

[0030] In this embodiment, each voice coil motor is provided with two sets of ceramic supports, which are respectively located on the radial sides of the voice coil motor; the two ends of the outer ring fixing part of the planar flexible hinge are respectively fixed to the top of the two sets of ceramic supports.

[0031] The stator of the voice coil motor is fixed on the base. A roller bracket is fixed on the lower surface of the moving platform for each voice coil motor, and a roller is rotatably mounted on the roller bracket. The rotation axis of the roller is set in the horizontal direction. When the moving platform performs angular leveling movement, a small radial relative rolling can be generated between the roller and the moving part of the voice coil motor to compensate for the radial displacement difference during the leveling process and eliminate lateral additional stress.

[0032] In this embodiment, the ceramic bracket is made of insulating ceramic material. A limiting structure is provided between the mating surface of the ceramic bracket and the mounting hole to limit the maximum stroke of the moving platform's Z-axis lifting and angle leveling.

[0033] At least three Z-axis displacement detection units are provided between the base and the moving platform, corresponding to the arrangement positions of the three voice coil motors, to collect the vertical displacement data of the moving platform in real time and calculate the pitch and yaw angle information.

Claims

1. A high-precision lifting-leveling integrated platform based on voice coil motor direct drive, comprising a base and a moving platform disposed above the base, wherein the horizontal plane on which the base is located is defined as the XY plane, and the vertical direction perpendicular to the XY plane is defined as the Z direction, and three voice coil motors are arranged circumferentially between the base and the moving platform, the output direction of each voice coil motor being set along the Z-axis, for coordinating to drive the moving platform to achieve Z-axis lifting motion and pitch and yaw two-dimensional angle leveling motion, characterized in that: It includes three planar flexible hinges, and the three planar flexible hinges are arranged in a one-to-one correspondence with the three voice coil motors along the circumferential direction; The stator of the voice coil motor is fixed to the base, and the mover is in direct contact with the moving platform. The Z-axis driving load is directly applied to the moving platform without being transmitted through the planar flexible hinge. The planar flexible hinge has a fixed part and a follower part. The fixed part is fixedly connected to the base, and the follower part is fixedly connected to the moving platform. As a parallel support and guide component, it synchronously adapts to the deformation of the moving platform. The stiffness of the planar flexible hinge in the XY plane is greater than that in the Z direction. It is used to constrain the horizontal translational displacement of the moving platform while bearing the load, and to isolate the interference of Z-direction movement and angle leveling on the positioning of the XY plane.

2. The high-precision lifting-leveling integrated platform according to claim 1, characterized in that: The lower surface of the moving platform is fixed with a roller bracket corresponding to each voice coil motor. A roller is rotatably mounted on the roller bracket. The outer circumferential surface of the roller makes rolling contact with the top surface of the moving element of the corresponding voice coil motor. The Z-axis driving load output by the voice coil motor acts directly on the moving platform through the roller and the roller bracket.

3. The high-precision lifting-leveling integrated platform according to claim 2, characterized in that: The moving platform has a through mounting hole along the Z direction for each planar flexible hinge. A ceramic bracket is fixed on the base, and the upper end of the ceramic bracket extends into the corresponding mounting hole. The planar flexible hinge is embedded in the mounting hole, and its fixed part is fixedly connected to the upper end of the ceramic bracket. The follower part is fixedly connected to the moving platform through a roller bracket.

4. The high-precision lifting-leveling integrated platform according to claim 3, characterized in that: The planar flexible hinge is a rectangular sheet structure with multiple slots arranged along a quasi-circular path. These slots separate and form an integrated outer ring fixing part, an inner ring following part, and a flexible deformation area connecting the two.

5. The high-precision lifting-leveling integrated platform according to claim 4, characterized in that: Each voice coil motor is provided with two sets of ceramic supports, which are located on the radial sides of the voice coil motor. The two ends of the outer ring fixing part of the planar flexible hinge are respectively fixed to the top of the two sets of ceramic supports.

6. The high-precision lifting-leveling integrated platform according to claim 4, characterized in that: Each voice coil motor is equipped with two sets of ceramic supports, which are located on the radial sides of the voice coil motor. The tops of the two sets of ceramic supports are connected as one unit by a ceramic connecting frame. The two ends of the outer ring fixing part of the planar flexible hinge are fixed on the ceramic connecting frame.

7. The high-precision lifting-leveling integrated platform according to claim 2, characterized in that: The rotation axis of the roller is set in the horizontal direction. When the moving platform is performing angle leveling motion, a small radial relative rolling can be generated between the roller and the moving part of the voice coil motor to compensate for the radial displacement difference during the leveling process and eliminate the lateral additional stress.

8. The high-precision lifting-leveling integrated platform according to claim 3, characterized in that: The ceramic support is made of insulating ceramic material.

9. The high-precision lifting-leveling integrated platform according to claim 1, characterized in that: At least three Z-axis displacement detection units are provided between the base and the moving platform, respectively corresponding to the arrangement positions of the three voice coil motors, for real-time acquisition of the vertical displacement data of the moving platform and calculation of pitch and yaw angle information.

10. The high-precision lifting-leveling integrated platform according to claim 3, characterized in that: A limiting structure is provided between the mating surface of the ceramic bracket and the mounting hole to limit the maximum stroke of the moving platform's Z-axis lifting and angle leveling.

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