High-precision large-thrust piezoelectric inchworm parallel six-degree-of-freedom motion platform
By using a high-precision, high-thrust piezoelectric inchworm-type parallel six-degree-of-freedom motion stage with a tenon-and-mortise limiting structure and a C-type clamping mechanism, the structural and control complexity of existing piezoelectric inchworm linear actuators has been solved, achieving high-precision, high-thrust drive with power-off self-locking, reduced assembly precision, and rapid response.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- A MI JING KONG KE JI (SHAN DONG) YOU XIAN GONG SI
- Filing Date
- 2026-05-08
- Publication Date
- 2026-07-31
AI Technical Summary
Existing piezoelectric linear actuators suffer from problems such as complex structure, non-compact design, complex control, high assembly precision, short step length of drive unit, inability to respond quickly, and inability to self-lock when power is off.
A high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion stage with a tenon-and-mortise limiting structure achieves power-off self-locking through the C-type clamping mechanism of the first and second clamping units. Combined with the flexible amplification mechanism of the first and second drive units, the assembly accuracy requirements are reduced, and a closed-loop control is performed using an LSTM predictive model.
It achieves a simple and compact structure, reliable clamping and release, power-off self-locking, large step length, high precision, and large thrust, and can quickly position and improve the driving load capacity.
Smart Images
Figure CN122495891A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nano-positioning technology, specifically to a high-precision, high-thrust piezoelectric grommets-type parallel six-degree-of-freedom motion stage. Background Technology
[0002] The piezoelectric inchworm linear actuator is a precision displacement actuator capable of achieving both large strokes at the millimeter and centimeter level and high resolution at the nanometer level. Based on the biomimetic principle of inchworm crawling, it continuously accumulates the minute displacements of the piezoelectric actuator to achieve continuous large-stroke displacement. Compared to electromagnetic linear motors, the piezoelectric inchworm linear actuator has advantages such as no magnetic field, ease of control, and no end effects or thrust fluctuations. Compared to ultrasonic resonant and inertial drive piezoelectric linear motors, it has advantages such as high output force, high power density, stable positioning, and no frictional wear. Therefore, in six-axis drive platforms requiring large strokes and high-resolution precision positioning, the piezoelectric inchworm linear motor is more advantageous. However, the piezoelectric inchworm linear motor currently still has the following shortcomings: 1) The overall structure of the driver is complex, not compact, and its control is complicated; 2) The clamping displacement or release displacement of the clamping unit is the output displacement of the piezoelectric actuator. The output displacement of the piezoelectric actuator is very small. In order for the clamping unit to clamp and release reliably, the clamping unit and the drive unit are required to have very high machining and assembly precision. 3) If the drive unit uses piezoelectric ceramic direct drive, the step size of the entire driver will be shortened, and it will not be able to meet the requirements of fast response in terms of travel speed. Using an amplification mechanism will reduce the load capacity of the entire driver. 4) The motor cannot achieve self-locking when power is off. Summary of the Invention
[0003] (a) Technical problems to be solved The technical problem to be solved by the present invention is to provide a high-precision, high-thrust piezoelectric gauging wire parallel six-degree-of-freedom motion stage that is simple and compact in structure, adopts a tenon and mortise limiting structure to reduce assembly accuracy requirements, can achieve full clamping and release, power-off self-locking, large step length, high precision, and large thrust, in view of the current status of the prior art.
[0004] A parallel six-DOF motion platform is a typical parallel mechanism, whose moving platform can move in six directions in space, namely three translational degrees of freedom and three rotational degrees of freedom. Three translational degrees of freedom: lateral translation of the moving platform along the X-axis, longitudinal translation along the Y-axis, and vertical translation along the Z-axis; Three rotational degrees of freedom: pitch rotation (θX) about the X-axis, roll rotation (θY) about the Y-axis, and yaw rotation (θZ) about the Z-axis; These six degrees of freedom are coupled together, and the position and orientation of the moving platform in space can be achieved by the coordinated expansion and contraction of each branch.
[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a high-precision, high-thrust piezoelectric grommets-type parallel six-degree-of-freedom motion table, comprising a base, a motion table, and an output shaft, characterized in that: the output shaft is connected between the base and the motion table, and a first drive unit and a second drive unit are sleeved on the outer surface of the output shaft; The first drive unit is provided with a first clamping unit at the left end, and the second drive unit is provided with a second clamping unit at the right end. The first clamping unit and the second clamping unit are respectively clamped on the outer surface of the output shaft. The first drive unit includes a second rigid part and a third rigid part arranged along the output shaft axis, and a first flexible amplification mechanism and a first drive piezoelectric ceramic are provided between the second rigid part and the third rigid part. The first clamping unit has the same structure as the second clamping unit.
[0006] Preferably, both the first clamping unit and the second clamping unit include a first rigid part, a C-type clamping mechanism, an ear-shaped protrusion, a first through hole, a piezoelectric ceramic for clamping, and a preload screw hole; The C-type clamping mechanism and the output shaft are concentrically set, and the clamping piezoelectric ceramic is mounted on the middle of the C-type clamping mechanism.
[0007] Preferably, the outer peripheral surface of the second rigid part is provided with a first groove, and a first connecting threaded hole is provided in the first groove; The ear-shaped protrusion is fitted into the first groove, and the first through hole and the first connecting threaded hole are coaxially arranged and fixedly connected by bolts.
[0008] Preferably, the first flexible amplification mechanism is provided with a boss, and a first pre-tightening through hole is provided between the boss and the third rigid part; A first preload screw is fitted inside the first preload through hole. The first preload screw is used to tighten the first driving piezoelectric ceramic.
[0009] Preferably, the third rigid part is provided with a first fixing threaded hole and a first connecting hole; The third rigid part is provided with a first limiting part, a second limiting part, and a third limiting part; The fourth rigid part of the second drive unit is provided with a second fixed threaded hole and a second connecting hole; The fourth rigid part is provided with a fourth limiting part, a fifth limiting part, and a sixth limiting part.
[0010] Preferably, the first connecting hole and the second connecting hole are coaxially corresponding, and connecting screws are inserted into the first connecting hole and the second connecting hole, and the first driving unit and the second driving unit are connected together by the connecting screws.
[0011] Preferably, the second drive unit includes a fifth rigid part, and a second groove is formed on the outer peripheral surface of the fifth rigid part; The second groove has a second connecting threaded hole. The first through hole on the second clamping unit is coaxially arranged with the second connecting threaded hole and is fixedly connected by bolts.
[0012] Preferably, the second drive unit is provided with a second flexible amplification mechanism, and a second pre-tightening through hole is provided between the second flexible amplification mechanism and the fourth rigid part, and a second pre-tightening screw is assembled in the second pre-tightening through hole.
[0013] Operating method of high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion table: S1: Target pose input. After the system starts, the target pose data is input by the host computer or user interface. The target pose includes the desired position parameters in six degrees of freedom directions, namely, X-axis translational displacement, Y-axis translational displacement, Z-axis translational displacement, rotation angle Rx around the X-axis, rotation angle Ry around the Y-axis, and rotation angle Rz around the Z-axis.
[0014] S2: Data preprocessing and LSTM prediction. Collect the actual pose data of the platform at the current and historical moments, normalize the data, and construct the input sequence using the sliding window method. The window length can be preset to N time steps according to the system sampling frequency and prediction accuracy requirements. The constructed input sequence is fed into the pre-trained LSTM prediction model. The LSTM model includes a forget gate, an input gate, an output gate, and a cell state update unit, which is used to output the predicted pose of the platform at future moments. This predicted pose serves as the reference trajectory for subsequent control steps.
[0015] S3: Error judgment and closed-loop control start. The actual pose of the current platform is compared with the LSTM predicted pose obtained in step two. The pose deviation vector is calculated. If the magnitude of the pose deviation vector is less than a preset threshold, it is determined that the platform has reached the predicted position. The current pose is directly output and the process ends. If the magnitude of the pose deviation vector is greater than or equal to the preset threshold, the closed-loop control process is started.
[0016] S4: Control strategy selection and drive signal generation. Based on the platform motion mode selection command, the system enters one of the following two control modes: Method 1: Parallel control method. Through a six-degree-of-freedom decoupling controller, the pose deviation obtained in step 3 is converted into the driving voltage signal required by each of the six piezoelectric ceramic actuators. Each actuator independently controls the displacement output in one degree of freedom direction. Method 2: Inchworm stepping master-slave control mode. First, the active cylinder and the driven cylinder in the platform drive unit are determined. The active cylinder is used to perform large step coarse adjustment movement, and the driven cylinder is used to perform small step fine adjustment movement. Through the inchworm stepping mechanism of alternating clamping and extension of the active cylinder and the driven cylinder, the cumulative stepping movement of the platform in six degrees of freedom is realized. This method is suitable for large stroke motion scenarios.
[0017] S5: Platform driving and real-time displacement feedback. The driving voltage signal generated in step four is applied to the piezoelectric ceramic actuator to drive the platform to generate displacement. At the same time, the displacement sensor arranged on the platform collects the current actual position and posture of the platform in real time. The displacement sensor is preferably a capacitive displacement sensor or a laser displacement meter.
[0018] S6: Error Comparison and Parameter Adaptive Update. The actual pose fed back in step five is compared again with the LSTM predicted pose in step two to calculate the real-time pose error. Based on this real-time error, the control parameters of the controller are updated, including but not limited to the proportional, integral, and derivative gain coefficients of the PID controller, or the switching gain and boundary layer thickness of the sliding mode controller. Optionally, the LSTM prediction model is fine-tuned online by using mini-batch gradient descent or recursive least squares to update the model weights, so that the prediction output better matches the current dynamic characteristics of the platform.
[0019] S7: Iteration loop and termination condition. Repeat steps S2 to S6 to form a closed-loop iterative process of "prediction-control-feedback-correction" until the pose deviation is determined to be less than the preset threshold in step three. At this time, the system outputs the final pose of the platform and completes this motion control.
[0020] (III) Beneficial Effects Compared with the prior art, the present invention provides a high-precision, high-thrust piezoelectric grommets-type parallel six-degree-of-freedom motion stage, which has the following advantages: (1) The high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion table has a simple and compact overall structure. The first clamping unit and the second clamping unit can achieve self-locking when the power is off. In the power-off state, the C-type clamping mechanism automatically clamps the output shaft to complete the clamping and fixing.
[0021] (2) The high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion stage has an integrated structure for the first clamping unit and the second clamping unit, and an integrated structure for the first driving unit and the second driving unit, eliminating the need for multi-part assembly and adjustment processes.
[0022] (3) The high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion table has a mortise and tenon joint between the third and fourth rigid parts to reduce the assembly error between the first and second drive units.
[0023] (4) The high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion stage adopts a C-type clamping mechanism in the first clamping unit and the second clamping unit. The C-type clamping mechanism is easy to assemble and adjust. The C-type clamping mechanism can realize the full release and full clamping of the output shaft, reduce the friction and wear between the output shaft and the C-type clamping mechanism, and improve the driving force of the output shaft.
[0024] (5) The high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion stage has a first flexible amplification mechanism and a second flexible amplification mechanism that can amplify the driving displacement and improve the driving accuracy. The dual driving mechanism of the first driving unit and the second driving unit is adopted to accelerate the driving speed of the mechanism and achieve rapid positioning. The flexible amplification mechanism can effectively utilize the driving force of piezoelectric ceramics to enhance the driving load capacity of the mechanism. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the high-precision, high-thrust piezoelectric grommets in parallel six-degree-of-freedom motion table structure of the present invention; Figure 2 This is a schematic diagram of the connection structure at the output shaft of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention viewed from a perspective perpendicular to the output axis; Figure 4 This is a schematic diagram of the full cross-sectional structure of the output shaft of the present invention; Figure 5 This is a schematic diagram of the first clamping unit structure of the present invention; Figure 6 This is a schematic diagram of the structure of the first driving unit of the present invention; Figure 7 This is a schematic diagram of the structure of the second driving unit of the present invention; Figure 8 This is a power-on timing diagram of the first clamping unit, the driving unit, and the second clamping unit of the present invention; Figure 9 This is a flowchart of the process of the present invention.
[0026] In the figure: 1. First clamping unit; 11. First rigid part; 12. C-type clamping mechanism; 13. Ear-shaped protrusion; 131. First through hole; 14. Piezoelectric ceramic for clamping; 15. Preload screw hole; 2. First drive unit; 21. Second rigid part; 211. First groove; 212. First connecting threaded hole; 22. First flexible amplification mechanism; 221. Boss; 23. First preload through hole; 231. First preload screw; 24. Third rigid part; 241. First fixing threaded hole; 242. First connecting hole; 243. First limiting part; 244. 245. Second limiting part; 245. Third limiting part; 26. First driving piezoelectric ceramic; 3. Output shaft; 4. Second driving unit; 41. Fifth rigid part; 411. Second groove; 412. Second connecting threaded hole; 42. Second flexible amplification mechanism; 43. Second pre-tightening through hole; 431. Second pre-tightening screw; 44. Fourth rigid part; 441. Second fixing threaded hole; 442. Second connecting hole; 443. Fourth limiting part; 444. Fifth limiting part; 445. Sixth limiting part; 5. Second clamping unit; 6. Connecting screw; 7. Base; 8. Motion table. Detailed Implementation
[0027] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.
[0028] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0029] In the description of this invention, terms such as greater than, less than, and exceeding are understood to exclude the stated number, while terms such as above, below, and within are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0030] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.
[0031] Please see Figures 1 to 9This invention provides a new technical solution: a high-precision, high-thrust piezoelectric grommets-type parallel six-degree-of-freedom motion stage, including a base 7, a motion stage 8, and an output shaft 3. The output shaft 3 is connected between the base 7 and the motion stage 8, and there are six output shafts 3. A first driving unit 2 and a second driving unit 4 are sleeved on the outer surface of the output shaft 3. A first clamping unit 1 is provided at the left end of the first driving unit 2, and a second clamping unit 5 is provided at the right end of the second driving unit 4. The first clamping unit 1 and the second clamping unit 5 are respectively clamped on the outer surface of the output shaft 3. The first driving unit 2 includes a second rigid part 21 and a third rigid part 24 arranged along the axial direction of the output shaft 3. A first flexible amplification mechanism 22 and a first driving piezoelectric ceramic 26 are provided between the second rigid part 21 and the third rigid part 24. The first clamping unit 1 and the second clamping unit 5 have the same structure.
[0032] Furthermore, both the first clamping unit 1 and the second clamping unit 5 include a first rigid part 11, a C-type clamping mechanism 12, an ear-shaped protrusion 13, a first through hole 131, a clamping piezoelectric ceramic 14, and a pre-tightening screw hole 15. The C-type clamping mechanism 12 and the output shaft 3 are concentrically arranged, and the clamping piezoelectric ceramic 14 is abutted on the middle of the C-type clamping mechanism 12.
[0033] Furthermore, a first groove 211 is provided on the outer peripheral surface of the second rigid part 21, and a first connecting threaded hole 212 is provided in the first groove 211. The ear-shaped protrusion 13 is assembled in the first groove 211, and the first through hole 131 is coaxially arranged with the first connecting threaded hole 212 and fixedly connected by bolts.
[0034] Furthermore, the first flexible amplification mechanism 22 is provided with a boss 221, and a first pre-tightening through hole 23 is provided between the boss 221 and the third rigid part 24. A first pre-tightening screw 231 is installed in the first pre-tightening through hole 23, and the first pre-tightening screw 231 is used to tighten the first driving piezoelectric ceramic 26.
[0035] Furthermore, the third rigid part 24 is provided with a first fixing threaded hole 241 and a first connecting hole 242, and the third rigid part 24 is provided with a first limiting part 243, a second limiting part 244 and a third limiting part 245. The fourth rigid part 44 of the second drive unit 4 is provided with a second fixing threaded hole 441 and a second connecting hole 442, and the fourth rigid part 44 is provided with a fourth limiting part 443, a fifth limiting part 444 and a sixth limiting part 445.
[0036] Furthermore, the first connecting hole 242 and the second connecting hole 442 are coaxially corresponding, and connecting screws 6 are inserted into the first connecting hole 242 and the second connecting hole 442. The first driving unit 2 and the second driving unit 4 are connected together by the connecting screws 6.
[0037] Furthermore, the second drive unit 4 includes a fifth rigid part 41, the outer peripheral surface of the fifth rigid part 41 is provided with a second groove 411, the second groove 411 is provided with a second connecting threaded hole 412, the first through hole 131 on the second clamping unit 5 is coaxially arranged with the second connecting threaded hole 412 and is fixedly connected by bolts.
[0038] Furthermore, the second drive unit 4 is provided with a second flexible amplification mechanism 42, and a second pre-tightening through hole 43 is provided between the second flexible amplification mechanism 42 and the fourth rigid part 44. A second pre-tightening screw 431 is installed in the second pre-tightening through hole 43.
[0039] Working principle: The base 7 provides support for the whole, and the output shaft 3 connects the base 7 and the motion table 8. The motion table 8 moves synchronously with the output shaft 3. Through the timing on and off power control of the first clamping unit 1, the second clamping unit 5, the first drive unit 2, and the second drive unit 4, the output shaft 3 drives the motion table 8 to perform positive high-precision stepping motion. The specific single-cycle working principle is as follows: Release the second clamping unit 5: The clamping piezoelectric ceramic 14 of the second clamping unit 5 is energized, the clamping piezoelectric ceramic 14 extends, causing the C-type clamping mechanism 12 of the second clamping unit 5 to deform, releasing the clamping constraint on the output shaft 3. The first drive unit 2 and the second drive unit 4 extend, pushing the first clamping unit 1 to move forward.
[0040] After the clamping piezoelectric ceramic 14 of the second clamping unit 5 is energized and stabilized, the first driving piezoelectric ceramic 26 of the first driving unit 2 and the driving piezoelectric ceramic of the second driving unit 4 are synchronously energized. The first driving piezoelectric ceramic 26 elongates, and the displacement is amplified by the first flexible amplification mechanism 22, opening the gap between the second rigid part 21 and the third rigid part 24. The driving piezoelectric ceramic of the second driving unit 4 amplifies the displacement by the second flexible amplification mechanism 42, opening the gap between the fifth rigid part 41 and the fourth rigid part 44. The first driving unit 2 and the second driving unit 4 move forward along the output shaft 3 axis, synchronously driving the first clamping unit 1 and the output shaft 3 to move forward. The second clamping unit 5 re-clamps the output shaft 3: After the first driving piezoelectric ceramic 26 and the driving piezoelectric ceramic of the second driving unit 4 are energized and stabilized, the clamping piezoelectric ceramic 14 of the second clamping unit 5 is de-energized, the C-type clamping mechanism 12 of the second clamping unit 5 is deformed and reset, and the output shaft 3 is re-clamped.
[0041] Release the first clamping unit 1: After the clamping piezoelectric ceramic 14 of the second clamping unit 5 is de-energized and stabilized, the clamping piezoelectric ceramic 14 of the first clamping unit 1 is energized. The clamping piezoelectric ceramic 14 extends, causing the C-type clamping mechanism 12 of the first clamping unit 1 to deform, thereby releasing the clamping constraint on the output shaft 3. The first drive unit 2 and the second drive unit 4 are reset, driving the first clamping unit 1 to move in the opposite direction.
[0042] After the clamping piezoelectric ceramic 14 of the first clamping unit 1 is energized and stabilized, the first driving piezoelectric ceramic 26 and the driving piezoelectric ceramic of the second driving unit 4 are simultaneously de-energized. The first flexible amplification mechanism 22 and the second flexible amplification mechanism 42 are deformed and reset, driving the first clamping unit 1 to move in the reverse direction, pushing the output shaft 3 in the forward direction, and completing a single forward step of the output shaft 3.
[0043] The first clamping unit 1 re-clamps the output shaft 3: After the first drive unit 2 and the second drive unit 4 are de-energized and stabilized, the clamping piezoelectric ceramic 14 of the first clamping unit 1 is de-energized, the C-type clamping mechanism 12 of the first clamping unit 1 is deformed and reset, and the output shaft 3 is re-clamped, completing one motion cycle.
[0044] Working principle of auxiliary structure: The ear-shaped protrusion 13 of the first rigid part 11 is assembled in the first groove 211 of the second rigid part 21 and the second groove 411 of the fifth rigid part 41. The first through hole 131 is fixed with the first connecting threaded hole 212 and the second connecting threaded hole 412 by bolts to prevent the first rigid part 11 from rotating circumferentially and to ensure that the C-type clamping mechanism 12 is concentric with the output shaft 3. The first limiting part 243, the second limiting part 244, and the third limiting part 245 of the third rigid part 24 form a tenon and mortise limit with the fourth limiting part 443, the fifth limiting part 444, and the sixth limiting part 445 of the fourth rigid part 44 to limit the radial offset of the first driving unit 2 and the second driving unit 4.
[0045] Connecting screws 6 pass through the first connecting hole 242 and the second connecting hole 442 to securely connect the first driving unit 2 and the second driving unit 4. The first pre-tightening screw 231 passes through the first pre-tightening through hole 23 and the second pre-tightening screw 431 passes through the second pre-tightening through hole 43 to pre-tighten the first driving piezoelectric ceramic 26 and the driving piezoelectric ceramic of the second driving unit 4, respectively. The pre-tightening screw hole 15 is used for the pre-tightening installation of the clamping piezoelectric ceramic 14. The first fixing threaded hole 241 and the second fixing threaded hole 441 are used for the external fixation of the overall structure.
[0046] Structural Description: First Clamping Unit 1: The first clamping unit 1 is sleeved on the left end of the output shaft 3. The first clamping unit 1 is used to clamp the output shaft 3. The first clamping unit 1 is used to expand and release the output shaft 3. The first clamping unit 1 follows the first drive unit 2 to complete axial movement.
[0047] First rigid part 11: The first rigid part 11 is the main structure of the first clamping unit 1. The first rigid part 11 is used to fix the C-type clamping mechanism 12 and the ear-shaped protrusion 13. The first rigid part 11 maintains the overall structural stability of the first clamping unit 1.
[0048] C-type clamping mechanism 12: The C-type clamping mechanism 12 is concentrically set with the output shaft 3. The C-type clamping mechanism 12 clamps the output shaft 3 through elastic deformation and releases the output shaft 3 through elastic deformation. The C-type clamping mechanism 12 realizes the power-off self-locking function of the motion table.
[0049] Ear-shaped protrusion 13: Ear-shaped protrusion 13 is fixed to the outer peripheral surface of the first rigid part 11. Ear-shaped protrusion 13 is assembled inside the first groove 211. Ear-shaped protrusion 13 restricts the first rigid part 11 from circumferential rotation. Ear-shaped protrusion 13 ensures the concentricity of the C-type clamping mechanism 12 and the output shaft 3.
[0050] First through hole 131: The first through hole 131 is opened inside the ear-shaped protrusion 13. The first through hole 131 is coaxially set with the first connecting threaded hole 212. The first through hole 131 allows bolts to pass through to achieve fixed connection of components. The first through hole 131 improves the connection between the clamping unit and the drive unit.
[0051] Clamping piezoelectric ceramic 14: The clamping piezoelectric ceramic 14 is mounted on the middle of the C-type clamping mechanism 12. The clamping piezoelectric ceramic 14 extends when energized, pushing the C-type clamping mechanism 12 to expand. The clamping piezoelectric ceramic 14 retracts when de-energized, cooperating with the C-type clamping mechanism 12 to reset.
[0052] Preload screw hole 15: Preload screw hole 15 is formed on the surface of C-type clamping mechanism 12. Preload screw hole 15 is used for preload screw installation and fixation. Preload screw hole 15 realizes the preload installation of clamping piezoelectric ceramic 14 and prevents clamping piezoelectric ceramic 14 from loosening and displacement.
[0053] First drive unit 2: The first drive unit 2 is sleeved on the outer surface of the output shaft 3. The first drive unit 2 pushes the first clamping unit 1 to move axially through the extension action. The first drive unit 2 drives the first clamping unit 1 to move back through the reset action. The first drive unit 2 provides axial driving power for the output shaft 3.
[0054] Second rigid part 21: The second rigid part 21 is the end structure of the first drive unit 2. The second rigid part 21 is used to connect the first clamping unit 1. The second rigid part 21 is used to open the first groove 211. The second rigid part 21 maintains the structural strength of the end of the first drive unit 2.
[0055] First groove 211: The first groove 211 is formed on the outer peripheral surface of the second rigid part 21. The first groove 211 is used to assemble the ear-shaped protrusion 13. The first groove 211 restricts the circumferential rotation of the first rigid part 11. The first groove 211 improves the assembly accuracy of the clamping unit and the drive unit.
[0056] First connecting threaded hole 212: The first connecting threaded hole 212 is opened inside the first groove 211. The first connecting threaded hole 212 is coaxially set with the first through hole 131. The first connecting threaded hole 212 cooperates with the bolt to fix the component. The first connecting threaded hole 212 prevents the first rigid part 11 from axially disengaging.
[0057] First flexible amplification mechanism 22: The first flexible amplification mechanism 22 connects the second rigid part 21 and the third rigid part 24. The first flexible amplification mechanism 22 amplifies the output displacement of the first driving piezoelectric ceramic 26. The first flexible amplification mechanism 22 opens the gap of the rigid part through elastic deformation. The first flexible amplification mechanism 22 drives the rigid part to close through elastic reset.
[0058] Boss 221: Boss 221 is provided on the surface of the first flexible amplification mechanism 22. Boss 221 cooperates with the third rigid part 24 to form the first pre-tightening through hole 23. Boss 221 provides installation support for the first pre-tightening screw 231 and ensures the installation position accuracy of the first pre-tightening screw 231.
[0059] First pre-tightening through hole 23: The first pre-tightening through hole 23 is formed between the boss 221 and the third rigid part 24. The first pre-tightening through hole 23 allows the first pre-tightening screw 231 to pass through and be installed. The first pre-tightening through hole 23 defines the installation path of the first pre-tightening screw 231. The first pre-tightening through hole 23 realizes the pre-tightening positioning of the first driving piezoelectric ceramic 26.
[0060] First preload screw 231: The first preload screw 231 is assembled inside the first preload through hole 23. The first preload screw 231 presses against the first driving piezoelectric ceramic 26. The first preload screw 231 prevents the first driving piezoelectric ceramic 26 from shaking and ensures the driving stability of the first driving piezoelectric ceramic 26.
[0061] Third rigid part 24: The third rigid part 24 is the middle structure of the first drive unit 2. The third rigid part 24 is used to open the first fixed threaded hole 241, the third rigid part 24 is used to open the first connecting hole 242, the third rigid part 24 is used to set the first limiting part 243, the second limiting part 244, and the third limiting part 245. The third rigid part 24 maintains the structural integrity of the middle part of the first drive unit 2.
[0062] First fixed threaded hole 241: The first fixed threaded hole 241 is formed on the surface of the third rigid part 24. The first fixed threaded hole 241 is used for the installation and connection of external fasteners. The first fixed threaded hole 241 realizes the external fixation of the first drive unit 2. The first fixed threaded hole 241 improves the overall installation stability of the motion table.
[0063] First connecting hole 242: The first connecting hole 242 is opened inside the third rigid part 24. The first connecting hole 242 and the second connecting hole 442 are coaxially corresponding. The first connecting hole 242 is for the connecting screw 6 to pass through and install. The first connecting hole 242 realizes the fixed connection between the first drive unit 2 and the second drive unit 4.
[0064] First limiting part 243: The first limiting part 243 is disposed on the surface of the third rigid part 24. The first limiting part 243 cooperates with the fourth limiting part 443 to achieve tenon and mortise limiting. The first limiting part 243 restricts the radial offset of the first driving unit 2 and the second driving unit 4. The first limiting part 243 improves the assembly accuracy of the dual driving units.
[0065] Second limiting part 244: The second limiting part 244 is disposed on the surface of the third rigid part 24. The second limiting part 244 cooperates with the fifth limiting part 444 to achieve tenon and mortise limiting. The second limiting part 244 restricts the radial offset of the first driving unit 2 and the second driving unit 4. The second limiting part 244 improves the motion synchronization of the two driving units.
[0066] Third limiting part 245: The third limiting part 245 is disposed on the surface of the third rigid part 24. The third limiting part 245 cooperates with the sixth limiting part 445 to realize tenon and mortise limiting. The third limiting part 245 restricts the radial offset between the first driving unit 2 and the second driving unit 4. The third limiting part 245 reduces the running error of the motion table.
[0067] First driving piezoelectric ceramic 26: The first driving piezoelectric ceramic 26 is assembled inside the first flexible amplification mechanism 22. The first driving piezoelectric ceramic 26 provides driving power by extending when energized and completes the reset action by contracting when de-energized. The first driving piezoelectric ceramic 26 provides core driving energy for the first driving unit 2.
[0068] Output shaft 3: Output shaft 3 connects base 7 and motion table 8. Output shaft 3 receives the driving force of first clamping unit 1 and the pushing force of drive unit. Output shaft 3 drives motion table 8 to complete six-degree-of-freedom precision displacement motion. There are six output shafts 3.
[0069] Second drive unit 4: The second drive unit 4 is sleeved on the outer surface of the output shaft 3. The second drive unit 4, through its extension action, cooperates with the first drive unit 2 to push the output shaft 3 to move. The second drive unit 4, through its reset action, cooperates with the first drive unit 2 to complete the return movement. The second drive unit 4 increases the driving thrust and step length of the motion table.
[0070] Fifth rigid part 41: The fifth rigid part 41 is the end structure of the second drive unit 4. The fifth rigid part 41 is used to connect the second clamping unit 5. The fifth rigid part 41 is used to open the second groove 411. The fifth rigid part 41 maintains the structural strength of the end of the second drive unit 4.
[0071] Second groove 411: The second groove 411 is formed on the outer peripheral surface of the fifth rigid part 41. The second groove 411 is used to assemble the ear-shaped protrusion 13 of the second clamping unit 5. The second groove 411 restricts the circumferential rotation of the second clamping unit 5 and improves the assembly accuracy of the second clamping unit 5.
[0072] Second connecting threaded hole 412: The second connecting threaded hole 412 is opened inside the second groove 411. The second connecting threaded hole 412 is coaxially set with the first through hole 131 of the second clamping unit 5. The second connecting threaded hole 412 cooperates with the bolt to fix the component. The second connecting threaded hole 412 prevents the second clamping unit 5 from axially disengaging.
[0073] Second flexible amplification mechanism 42: The second flexible amplification mechanism 42 connects the fifth rigid part 41 and the fourth rigid part 44. The second flexible amplification mechanism 42 amplifies the output displacement of the piezoelectric ceramic of the second drive unit 4. The second flexible amplification mechanism 42 opens the gap of the rigid part through elastic deformation. The second flexible amplification mechanism 42 drives the rigid part to close through elastic reset.
[0074] Second pre-tightening through hole 43: The second pre-tightening through hole 43 is opened between the second flexible amplification mechanism 42 and the fourth rigid part 44. The second pre-tightening through hole 43 allows the second pre-tightening screw 431 to pass through and be installed. The second pre-tightening through hole 43 limits the installation path of the second pre-tightening screw 431. The second pre-tightening through hole 43 realizes the pre-tightening positioning of the piezoelectric ceramic of the second drive unit 4.
[0075] Second preload screw 431: The second preload screw 431 is installed inside the second preload through hole 43. The second preload screw 431 presses against the piezoelectric ceramic of the second drive unit 4. The second preload screw 431 prevents the piezoelectric ceramic of the second drive unit 4 from shaking. The second preload screw 431 ensures the driving stability of the second drive unit 4.
[0076] Fourth rigid part 44: The fourth rigid part 44 is the middle structure of the second drive unit 4. The fourth rigid part 44 is used to open the second fixed threaded hole 441, the fourth rigid part 44 is used to open the second connecting hole 442, the fourth rigid part 44 is used to set the fourth limiting part 443, the fifth limiting part 444, and the sixth limiting part 445. The fourth rigid part 44 maintains the structural integrity of the middle part of the second drive unit 4.
[0077] Second fixing threaded hole 441: The second fixing threaded hole 441 is opened on the surface of the fourth rigid part 44. The second fixing threaded hole 441 is used for the installation and connection of external fasteners. The second fixing threaded hole 441 realizes the external fixation of the second drive unit 4. The second fixing threaded hole 441 improves the overall installation stability of the motion table.
[0078] Second connecting hole 442: The second connecting hole 442 is opened inside the fourth rigid part 44. The second connecting hole 442 is coaxially corresponding with the first connecting hole 242. The second connecting hole 442 is used for the connecting screw 6 to pass through and install. The second connecting hole 442 realizes the fixed connection between the second drive unit 4 and the first drive unit 2.
[0079] Fourth limiting part 443: The fourth limiting part 443 is disposed on the surface of the fourth rigid part 44. The fourth limiting part 443 cooperates with the first limiting part 243 to realize tenon and mortise limiting. The fourth limiting part 443 restricts the radial offset between the second driving unit 4 and the first driving unit 2. The fourth limiting part 443 improves the assembly accuracy of the dual driving units.
[0080] Fifth limiting part 444: The fifth limiting part 444 is disposed on the surface of the fourth rigid part 44. The fifth limiting part 444 cooperates with the second limiting part 244 to achieve tenon and mortise limiting. The fifth limiting part 444 restricts the radial offset between the second drive unit 4 and the first drive unit 2. The fifth limiting part 444 improves the motion synchronization of the two drive units.
[0081] The sixth limiting part 445 is provided on the surface of the fourth rigid part 44. The sixth limiting part 445 cooperates with the third limiting part 245 to achieve tenon and mortise limiting. The sixth limiting part 445 restricts the radial offset between the second drive unit 4 and the first drive unit 2. The sixth limiting part 445 reduces the running error of the motion table.
[0082] Second clamping unit 5: The second clamping unit 5 is sleeved on the right end of the output shaft 3. The second clamping unit 5 is used to clamp the output shaft 3, and to release the output shaft 3. The second clamping unit 5 fixes the stepping position of the output shaft 3.
[0083] Connecting screw 6: The connecting screw 6 passes through the inside of the first connecting hole 242 and the second connecting hole 442. The connecting screw 6 fixes the first drive unit 2 and the second drive unit 4 into one unit. The connecting screw 6 improves the connection firmness of the two drive units and ensures the motion synchronization of the two drive units.
[0084] Base 7: Base 7 is the bottom support structure of the motion table. Base 7 is used to fix the bottom position of the output shaft 3. Base 7 provides stable support for the entire motion table and prevents the bottom of the motion table from shaking.
[0085] Motion table 8: The motion table 8 is connected to the top of the output shaft 3. The motion table 8 follows the output shaft 3 to complete synchronous displacement movement. The motion table 8 realizes six-degree-of-freedom precision positioning output. The motion table 8 carries external loads to complete precision displacement operations.
[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A high-precision large-thrust piezoelectric inchworm parallel six-degree-of-freedom motion platform, comprising a base (7), a motion platform (8) and an output shaft (3), characterized in that: The output shaft (3) is connected between the base (7) and the motion table (8), and the first drive unit (2) and the second drive unit (4) are sleeved on the outer surface of the output shaft (3). The first drive unit (2) is provided with a first clamping unit (1) on the left end, and the second drive unit (4) is provided with a second clamping unit (5) on the right end. The first clamping unit (1) and the second clamping unit (5) are respectively clamped on the outer surface of the output shaft (3); The first drive unit (2) includes a second rigid part (21) and a third rigid part (24) arranged along the output shaft (3) axially. A first flexible amplification mechanism (22) and a first drive piezoelectric ceramic (26) are provided between the second rigid part (21) and the third rigid part (24). The first clamping unit (1) has the same structure as the second clamping unit (5).
2. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 1, characterized in that: Both the first clamping unit (1) and the second clamping unit (5) include a first rigid part (11), a C-type clamping mechanism (12), an ear-shaped protrusion (13), a first through hole (131), a clamping piezoelectric ceramic (14), and a pre-tightening screw hole (15). The C-type clamping mechanism (12) and the output shaft (3) are concentrically arranged, and the clamping piezoelectric ceramic (14) is mounted on the middle of the C-type clamping mechanism (12).
3. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 1, characterized in that: The outer peripheral surface of the second rigid part (21) is provided with a first groove (211), and a first connecting threaded hole (212) is provided in the first groove (211). The ear-shaped protrusion (13) is fitted into the first groove (211), and the first through hole (131) and the first connecting threaded hole (212) are coaxially arranged and fixedly connected by bolts.
4. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 1, characterized in that: The first flexible amplification mechanism (22) is provided with a boss (221), and a first pre-tightening through hole (23) is provided between the boss (221) and the third rigid part (24). The first preload through hole (23) is fitted with a first preload screw (231), which is used to tighten the first drive piezoelectric ceramic (26).
5. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion table according to claim 1, characterized in that: The third rigid part (24) is provided with a first fixed threaded hole (241) and a first connecting hole (242). The third rigid part (24) is provided with a first limiting part (243), a second limiting part (244) and a third limiting part (245); The second drive unit (4) has a second fixed threaded hole (441) and a second connecting hole (442) on its fourth rigid part (44). The fourth rigid part (44) is provided with a fourth limiting part (443), a fifth limiting part (444) and a sixth limiting part (445).
6. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 5, characterized in that: The first connecting hole (242) and the second connecting hole (442) are coaxially corresponding. A connecting screw (6) is inserted into the first connecting hole (242) and the second connecting hole (442). The first driving unit (2) and the second driving unit (4) are connected together by the connecting screw (6).
7. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 1, characterized in that: The second drive unit (4) includes a fifth rigid part (41), and a second groove (411) is provided on the outer peripheral surface of the fifth rigid part (41). The second groove (411) has a second connecting threaded hole (412). The first through hole (131) on the second clamping unit (5) is coaxially arranged with the second connecting threaded hole (412) and is fixedly connected by bolts.
8. The high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion stage according to claim 7, characterized in that: The second drive unit (4) is provided with a second flexible amplification mechanism (42), and a second pre-tightening through hole (43) is provided between the second flexible amplification mechanism (42) and the fourth rigid part (44), and a second pre-tightening screw (431) is installed in the second pre-tightening through hole (43). Operating method of high-precision, high-thrust piezoelectric gaiter-type parallel six-degree-of-freedom motion table: S1: Target pose input. After the system starts, the target pose data is input by the host computer or user interface. The target pose includes the desired position parameters in six degrees of freedom directions, namely, X-axis translational displacement, Y-axis translational displacement, Z-axis translational displacement, rotation angle Rx around the X-axis, rotation angle Ry around the Y-axis, and rotation angle Rz around the Z-axis. S2: Data preprocessing and LSTM prediction: Collect the actual pose data of the platform at the current and historical moments, normalize the data, and construct the input sequence using the sliding window method. The window length can be preset to N time steps according to the system sampling frequency and prediction accuracy requirements. The constructed input sequence is fed into the pre-trained LSTM prediction model. The LSTM model includes a forget gate, an input gate, an output gate, and a cell state update unit, which is used to output the predicted pose of the platform at future moments. This predicted pose serves as the reference trajectory for subsequent control steps. S3: Error judgment and closed-loop control start. The actual pose of the current platform is compared with the LSTM predicted pose obtained in step two. The pose deviation vector is calculated. If the magnitude of the pose deviation vector is less than the preset threshold, it is determined that the platform has reached the predicted position. The current pose is directly output and the process ends. If the magnitude of the pose deviation vector is greater than or equal to the preset threshold, the closed-loop control process is started. S4: Control strategy selection and drive signal generation. Based on the platform motion mode selection command, the system enters one of the following two control modes: Method 1: Parallel control method. Through a six-degree-of-freedom decoupling controller, the pose deviation obtained in step 3 is converted into the driving voltage signal required by each of the six piezoelectric ceramic actuators. Each actuator independently controls the displacement output in one degree of freedom direction. Method 2: Inchworm stepping master-slave control mode. First, the active cylinder and the driven cylinder in the platform drive unit are determined. The active cylinder is used to perform large step coarse adjustment movement, and the driven cylinder is used to perform small step fine adjustment movement. Through the inchworm stepping mechanism of alternating clamping and extension of the active cylinder and the driven cylinder, the cumulative stepping movement of the platform in six degrees of freedom is realized. This method is suitable for large stroke motion scenarios. S5: Platform driving and real-time displacement feedback. The driving voltage signal generated in step four is applied to the piezoelectric ceramic actuator to drive the platform to generate displacement. At the same time, the displacement sensor arranged on the platform collects the current actual position and posture of the platform in real time. The displacement sensor is preferably a capacitive displacement sensor or a laser displacement meter. S6: Error Comparison and Parameter Adaptive Update. The actual pose fed back in step five is compared again with the LSTM predicted pose in step two. The real-time pose error is calculated. Based on the real-time error, the control parameters of the controller are updated, including but not limited to the proportional, integral, and derivative gain coefficients of the PID controller, or the switching gain and boundary layer thickness of the sliding mode controller. Optionally, the LSTM prediction model is fine-tuned online, and the model weights are updated using mini-batch gradient descent or recursive least squares method to make the prediction output more consistent with the current dynamic characteristics of the platform. S7: Iteration loop and termination condition. Repeat steps S2 to S6 to form a closed-loop iterative process of "prediction-control-feedback-correction" until the pose deviation is determined to be less than the preset threshold in step three. At this time, the system outputs the final pose of the platform and completes this motion control.