Piezoelectric friction driving micro-nano displacement platform and driving method thereof

Abstract

The invention discloses a piezoelectric friction driving micro-nano displacement platform and a driving method thereof.The displacement platform comprises a base, a driving module, a displacement guide rail and an object carrying platform, the driving module comprises a supporting base, a driving piezoelectric actuator, a friction piezoelectric actuator, a driving body and a guiding hinge, the two actuators are installed on the supporting base, the driving foot drives the displacement guide rail in a friction mode, and the driving body drives the object carrying platform in a friction mode. The driving piezoelectric actuator is connected with one end of the driving body, and driving force of the friction piezoelectric actuator is perpendicular to the displacement guide rail and input from the other side of the driving body. The driving body is connected with the supporting seat through L-shaped guide hinges, and the four guide hinges are mutually symmetrical; the displacement table is large in load, high in speed and high in precision, micro-movement driving is achieved through the driving piezoelectric actuator, adhesion and separation control is achieved through the friction piezoelectric actuator, stick-slip state conversion does not exist, and non-contact withdrawing, sliding friction and return stroke errors are avoided; friction driving force and micro-motion driving force are guided through an L-shaped guide hinge, and micro-motion of the driving body in two dimensions is decoupled.

Description

Technical Field

[0001] The present invention relates to the field of micro piezoelectric drive technology, and in particular to a piezoelectric friction driven micro-nano displacement stage and a driving method thereof. Background Art

[0002] As an important component of the micro-nano positioning system, the micro-nano displacement platform is generally divided into two parts, the driving mechanism and the guiding mechanism. At the same time, the micro-nano displacement platform is also an important link between the macro and micro. With the rapid development of scanning probe microscopes, biomedical directions, precision manufacturing technology and chips, people's requirements for the positioning accuracy, travel and miniaturization design of micro-nano displacement platforms are gradually increasing.

[0003] At present, the micro-nano displacement stage with large stroke is mainly driven by stick-slip, but the existing stick-slip drive displacement stage structure has the following shortcomings: First, the same piezoelectric drive is used to realize stick contact and mobile drive at the same time. In the sticky state, a low-speed ramp signal is required to put the contact area in a static friction state to realize drive. In the slipping state, a high-speed ramp signal is required to realize sliding friction. The sliding friction of the displacement stage with this structure will cause return error, so there are theoretical shortcomings such as slow speed and low precision; second, the vertically arranged dual piezoelectric drives are used to drive and realize stick contact and mobile drive respectively, as shown in the patent CN201720661977.7, a stepping micro piezoelectric motor, which can avoid the return error caused by sliding friction in principle, but the piezoelectric displacement stage structure adopts a linear series arrangement, and the rear end drive is easy to produce parasitic displacement on the front end guide, and the control accuracy still needs to be improved. In addition, the displacement stage of this type of structure generally has a long unidirectional structural size, which is not conducive to the ingenious arrangement of the drive in the miniaturized design; third, there is a lack of self-locking design. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a piezoelectric friction driven micro-nano displacement stage and a driving method thereof to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A piezoelectric friction driven micro-nano displacement stage comprises a base, a driving module, a displacement guide rail and a loading platform. The base is in a U-shaped structure. The displacement guide rail is installed on the inner bottom surface of the base. The loading platform is supported by the displacement guide rail at the bottom and covers the upper port of the base. The driving module is installed on the inner bottom surface of the base and is used to drive the displacement guide rail and the loading platform to move relative to the base.

[0007] The driving module includes a support seat, a driving piezoelectric actuator, a friction piezoelectric actuator, a driving body and a guide hinge. The support seat is installed at the bottom of the base and has a driving groove on it. The driving piezoelectric actuator and the friction piezoelectric actuator are both installed on the support seat. The driving body is located in the driving groove, and a driving foot on one side of the driving body extends out of the driving groove and frictionally drives the displacement guide rail. The driving piezoelectric actuator is connected to one end of the driving body, and its micro-movement driving force is parallel to the displacement guide rail. The friction driving force of the friction piezoelectric actuator is input from the other side of the driving body and is perpendicular to the displacement guide rail; the driving body is connected to the support seat through four guide hinges. The guide hinges are L-shaped hinges. The four guide hinges are symmetrically arranged with one branch parallel to the displacement guide rail and the other branch perpendicular to the displacement guide rail, which are used to guide the micro-movement driving force and the friction driving force.

[0008] Furthermore, it also includes a self-locking mechanism, and the friction piezoelectric actuator transmits the friction driving force to the driving body through the self-locking mechanism. The self-locking mechanism includes a transmission lever and a self-locking spring. One end of the transmission lever is hinged to the support seat, and the other end is hinged to the driving body. The self-locking spring is installed on the support seat, one end of the self-locking spring is sleeved with a pre-tightening screw for pre-tightening and adjusting the initial friction force, and the other end elastically presses the other end of the transmission lever. The self-locking spring and the driving body are respectively located on both sides of the transmission lever, and the friction piezoelectric actuator drives the middle part of the transmission lever to generate a friction driving force perpendicular to the transmission lever and in the opposite direction to the clamping force of the self-locking spring.

[0009] Further, the piezoelectric actuator is driven to press-contact one end of the connecting driving body, and the root of the driving actuator is connected to the pre-tightening bolt.

[0010] Furthermore, a uniaxial flexible hinge perpendicular to the rod body and a mounting platform supported and connected by the uniaxial flexible hinge are provided in the middle of the transmission lever, the driving end of the friction piezoelectric actuator is connected to the mounting platform, and an adjusting gasket is provided between the two.

[0011] A driving method for a piezoelectric friction driven micro-nano displacement stage, comprising the following contents:

[0012] Both the piezoelectric actuator and the friction piezoelectric actuator are driven with a step excitation voltage. When the platform is slightly moved in the forward stroke, the piezoelectric actuator is first driven to apply a step voltage to drive the platform to complete a stepping micro-movement. Then, the friction piezoelectric actuator is applied with a step voltage to drive the foot to quickly leave the displacement guide rail, and then the driving voltage of the piezoelectric actuator is canceled to drive the piezoelectric actuator to retract and return. Finally, after returning to the initial position, the friction piezoelectric actuator voltage is canceled. This is a complete forward stepping cycle. This cycle is repeated continuously to achieve a large forward stroke displacement of nanometer-level micro-stepping.

[0013] When the loading platform performs a forward stroke micro-movement, first, the friction piezoelectric actuator applies a step voltage, and the driving foot quickly leaves the displacement guide rail; then, the driving piezoelectric actuator applies a step voltage to drive the loading platform to perform a step micro-movement back; then, the friction piezoelectric actuator voltage is canceled, and the driving foot gradually adheres to and connects to the displacement guide rail under the elastic compression of the self-locking spring; finally, the driving piezoelectric actuator voltage is canceled, and the driving piezoelectric actuator contracts to realize a complete reverse stepping cycle of the loading platform; this cycle is repeated continuously to realize a reverse large-stroke displacement of nanometer-level micro-stepping.

[0014] Compared with the prior art, the piezoelectric friction driven micro-nano displacement stage and the driving method thereof of the present invention have the following beneficial effects:

[0015] The micro-nano displacement platform realizes micro-movement drive by driving piezoelectric actuators and adhesion separation control by driving friction piezoelectric actuators. The adhesion process and friction driving process are independent and non-overlapping, and there is no stick-slip state conversion. The friction force can be increased by adjusting the driving displacement of the friction piezoelectric actuator, and the step micro-movement speed can be increased by increasing the frequency of driving the piezoelectric actuator. When the driving piezoelectric actuator and the driving body are withdrawn, it is a contactless withdrawal, there is no sliding friction, and therefore no return error will be generated. The vertical friction driving force and the parallel micro-movement driving force are guided by two symmetrical L-shaped guide hinges, and the micro-movement of the driving body in these two dimensions is decoupled to improve the accuracy of step micro-movement. The micro-nano displacement platform has a compact structure, a large load, a high speed and no return error. The self-locking mechanism configured can automatically lock the moving guide rail in the stopped state to improve the stability of the loading platform.

[0016] The driving method of the displacement stage is based on the structure of the driving module of the displacement platform. There is no stick-slip state change in the friction drive, and a self-buffering self-locking spring is provided. Therefore, both the driving piezoelectric actuator and the friction piezoelectric actuator can adopt a step excitation voltage, which significantly shortens the duration of a step cycle and effectively improves the stroke step efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side view of the overall structure of the micro-nano displacement stage of the present invention;

[0018] Figure 2 It is a front view of the internal structure of the micro-nano displacement stage of the present invention;

[0019] Figure 3 A three-dimensional view of the internal structure of the micro-nano displacement stage of the present invention;

[0020] Figure 4 A voltage excitation diagram of the forward stroke of the driving piezoelectric actuator of the micro-nano displacement stage of the present invention;

[0021] Figure 5This is a voltage excitation diagram of the forward stroke of the friction piezoelectric actuator of the micro-nano displacement stage of the present invention.

[0022] In the figure: 1. base; 2. driving module; 21. support seat; 22. driving piezoelectric actuator; 23. guide hinge; 24. friction piezoelectric actuator; 25. self-locking mechanism; 251. transmission lever; 252. self-locking spring; 26. driving body; 261. driving foot; 3. displacement guide rail; 31. outer track; 32. inner track; 4. loading platform. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only the best embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] A piezoelectric friction driven micro-nano displacement stage, such as Figure 1-Figure 3 As shown, a large displacement with nanometer resolution is generated by stepping drive, and the displacement target is placed on the loading platform 4. The loading platform 4 is supported by two sets of displacement guide rails 3 at the bottom and is in a horizontal state. The displacement guide rails 3 use cross roller guide rails, and the outer track 31 thereof is tightly positioned on the wall corner of the U-shaped structure base 1 and fixedly connected to the inner bottom surface of the base 1. The top of the inner track 32 is connected to the loading platform 4. The driving module 2 is installed on the inner bottom surface of the base 1, which is located in the space formed by the two sets of displacement guide rails 3 and the base 1, and is used to drive the inner track 32 of the displacement guide rail 3 and the loading platform 4 thereon to slightly move relative to the base 1;

[0025] The driving module 2 includes a driving piezoelectric actuator 22, a friction piezoelectric actuator 24, a support base 21, a driving body 26 integrally formed with the support base 21, a self-locking mechanism 25 and a guide hinge 23. Figure 2-Figure 3 The support seat 21 is cut by wire to form a driving groove for installing the driving body 26, a lever groove for installing the self-locking mechanism 25, a spring groove and two piezoelectric grooves. The four corners of the support seat 21 are fixedly connected to the inner bottom surface of the base 1, and all components are arranged on the support seat 21 in an embedded manner;

[0026] The driving body 26 is located in the driving groove, and a driving foot 261 is protruding from one side of the driving body 26. The driving foot 261 extends out of the driving groove. Under normal conditions, it vertically presses against the inner track 32 of one of the displacement guide rails 3 to lock the stopped state of the loading platform 4. The driving body 26 is square, and a piezoelectric body groove is opened on the inner groove surface of one side of the driving groove. The driving piezoelectric actuator 22 is positioned and installed in the piezoelectric body groove by a pre-tightening bolt, and its driving end extends out of the piezoelectric body groove and presses against one end of the driving body 26 for inputting a micro-movement driving force along the direction of the displacement guide rail 3, and can avoid coupling input in the direction of the vertical displacement guide rail 3. The micro-movement driving force and the self-locking clamping force in the direction of the vertical displacement guide rail 3 are input from the other side of the driving body 26.

[0027] The driving body 26 is connected to the support seat 21 through four L-shaped guide hinges 23. The four guide hinges 23 are arranged in a mutually symmetrical structure, one end of which is connected to the side of the driving body 26, and the other end is connected to the inner groove surface of the driving groove. One branch of the L-shaped guide hinge 23 is parallel to the displacement guide rail 3, which is used to guide the micro-movement driving force along the displacement guide rail 3, and the other branch is perpendicular to the displacement guide rail 3, which is used to guide the friction driving force perpendicular to the displacement guide rail 3. The setting of the L-shaped guide hinge 23 decouples the micro-movement of the driving body 26 in two dimensions, thereby improving the micro-movement accuracy of the micro-nano displacement stage.

[0028] Among them, the self-locking mechanism 25 includes a transmission lever 251 and a self-locking spring 252. In order to automatically achieve the stability of the loading platform 4 in the stopped state, the self-locking mechanism 25 automatically releases the elastic self-locking clamping force, and uses the state stability of the driving body 26 itself to lock the displacement guide 3 and the loading platform 4 thereon. This embodiment adopts an implementation method that integrates self-locking and friction driving, that is, the friction piezoelectric actuator 24 transmits the friction driving force to the driving body 26 through the self-locking mechanism 25. When moving, the friction piezoelectric actuator 24 is zero voltage, and the self-locking force serves as a pressure-contact friction force, so that the driving foot 261 adheres to and presses the displacement guide 3 to drive the displacement guide 3 and the loading platform 4 thereon to move slightly; after completing the step-by-step micro-movement, the friction driving force generated by the friction piezoelectric actuator 24 serves as an unlocking force to release the adhesion and pressure contact of the driving foot 261, so that the driving foot 261 is separated from the displacement guide 3, and a non-sticky and slip-free retreat is achieved. After the retreat is completed, with the friction When the driving force is unloaded, the self-locking mechanism 25 automatically returns to the self-locking state; thus, the transmission lever 251 is arranged in the lever groove, one end of which is hingedly connected to the side of the lever groove as a rotation fulcrum of the transmission lever 251, and the other end is hingedly connected to the driving body 26 through a straight beam perpendicular to the displacement guide rail 3. The self-locking spring 252 is installed in the spring groove, and its end elastically presses the other end of the transmission lever 251. The self-locking spring 252 is a compression spring, and it and the driving body 26 are respectively located on both sides of the transmission lever 251 to push the driving foot 261 to press against the nearest displacement guide rail 3 for self-locking. The input point driven by the friction piezoelectric actuator 24 is located in the middle of the transmission lever 251. The micro-movement of the friction piezoelectric actuator 24 is amplified by the transmission lever 251, and a double adjustment rate is generated on the driving body 26, which accelerates the separation of the driving foot 261 from the displacement track, shortens the return waiting time of the driving piezoelectric actuator 22, and improves the step micro-movement efficiency.

[0029] Among them, another piezoelectric body groove is opened on the support body, which is connected to the lever groove. The transmission lever 251 is installed in the piezoelectric body groove. A uniaxial flexible hinge perpendicular to its rod body and a mounting platform supported and connected by the uniaxial flexible hinge are arranged in the middle of the transmission lever 251. The mounting platform extends into the piezoelectric body groove and is connected to the driving end of the friction piezoelectric actuator 24. The friction piezoelectric actuator 24 is pre-tightened by arranging an adjustment gasket between it and the mounting platform.

[0030] The driving method and working process of the piezoelectric friction driven micro-nano displacement stage of the best embodiment are as follows:

[0031] The piezoelectric actuator 22 and the friction piezoelectric actuator 24 are driven by a step-type excitation voltage, such as Figure 4-Figure 5As shown; when the loading platform 4 is slightly moved in the forward stroke, first, due to the elastic pressing force of the driving foot 261, it adheres to the displacement guide rail 3, and a step voltage is applied to the driving piezoelectric actuator 22. Under the guidance of the guide hinge 23, the driving body 26 is pushed to slightly move parallel to the guide rail, and the synchronous friction driving guide rail moves forward, driving the loading platform 4 to produce a step micro-movement; then, the friction piezoelectric actuator 24 applies a step voltage, and the driving foot 261 is pushed by the lever action. Under the guidance of the guide hinge 23, the driving foot 261 slightly moves perpendicular to the displacement guide rail 3 and quickly leaves the displacement guide rail 3, that is, enters the separation state, and then the driving piezoelectric actuator is canceled. 22 voltage is applied to drive the piezoelectric actuator 22 to retract and return, and under the action of the rebound force of the guide hinge 23, the driving body 26 returns to the initial position; finally, after driving the piezoelectric actuator 22 and the driving body 26 to return to the initial position, the voltage of the friction piezoelectric actuator 24 is canceled, and the driving foot 261 slowly contacts closely with the moving guide rail again under the action of the self-locking spring 252, and is connected to the moving guide rail by friction; thus, a complete positive stepping cycle is completed; this cycle is continuously repeated to realize the positive large-stroke displacement of nanometer-level micro-stepping, and the stopped state can be locked. The displacement platform can be used for large-load micro-nano displacement platforms and vertical micro-nano displacement platforms;

[0032] Of course, the micro-nano displacement stage can also realize a reverse stepping stroke. First, the friction piezoelectric actuator 24 applies a step voltage, and the driving foot 261 quickly leaves the displacement guide rail 3; then, the driving piezoelectric actuator 22 applies a step voltage to drive the object platform 4 to perform a step micro-movement retreat; then, the voltage of the friction piezoelectric actuator 24 is canceled, and the driving foot gradually adheres to and connects to the displacement guide rail 3 under the elastic compression of the self-locking spring 252; finally, the voltage of the driving piezoelectric actuator 22 is canceled, and the driving piezoelectric actuator 22 contracts to realize a complete reverse stepping cycle of the object platform 4; this cycle is repeated continuously to realize the reverse large-stroke displacement of nanometer-level micro-stepping.

[0033] The directional words such as "inside", "outside", "upper", "lower" and "bottom" mentioned in this article are based on Figure 1-Figure 3 The coordinates or orientations shown in . These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation;

[0034] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the terms "on" and "inside" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0035] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A piezoelectric friction driven micro-nano displacement stage, characterized in that: A base, a driving module, a displacement guide rail and a loading platform, wherein the base is in a U-shaped structure, the displacement guide rail is installed on the inner bottom surface of the base, the loading platform is supported by the displacement guide rail at the bottom and covers the upper port of the base, and the driving module is installed on the inner bottom surface of the base to drive the displacement guide rail and the loading platform to move relative to the base; The driving module includes a support seat, a driving piezoelectric actuator, a friction piezoelectric actuator, a driving body and a guide hinge. The support seat is installed at the bottom of the base and has a driving groove on it. The driving piezoelectric actuator and the friction piezoelectric actuator are both installed on the support seat. The driving body is located in the driving groove, and a driving foot on one side of the driving body extends out of the driving groove and frictionally drives the displacement guide rail. The driving piezoelectric actuator is connected to one end of the driving body, and its micro-movement driving force is parallel to the displacement guide rail. The friction driving force of the friction piezoelectric actuator is input from the other side of the driving body and is perpendicular to the displacement guide rail. The driving body is connected to the support seat through four guide hinges. The guide hinges are L-shaped hinges. The four guide hinges are symmetrically arranged with one branch being parallel to the displacement guide rail and the other branch being perpendicular to the displacement guide rail, and are used to guide the micro-movement driving force and the friction driving force.

2. The piezoelectric friction driven micro-nano displacement stage according to claim 1, characterized in that: It also includes a self-locking mechanism, through which the friction piezoelectric actuator transmits the friction driving force to the driving body, and the self-locking mechanism includes a transmission lever and a self-locking spring. One end of the transmission lever is hingedly connected to the support seat, and the other end is hingedly connected to the driving body. The self-locking spring is installed on the support seat, one end of which is sleeved with a pre-tightening screw for pre-tightening and adjusting the initial friction force, and the other end elastically presses the other end of the transmission lever. The self-locking spring and the driving body are respectively located on both sides of the transmission lever, and the friction piezoelectric actuator is driven and connected to the middle part of the transmission lever to generate a friction driving force perpendicular to the transmission lever and in the opposite direction to the clamping force of the self-locking spring.

3. The piezoelectric friction driven micro-nano displacement stage according to claim 2, characterized in that: The driving piezoelectric actuator is pressed and connected to one end of the driving body, and the root of the driving piezoelectric actuator is connected to the supporting seat through a pre-tightening bolt.

4. The piezoelectric friction driven micro-nano displacement stage according to claim 2, characterized in that: The middle part of the transmission lever is provided with a uniaxial flexible hinge perpendicular to the rod body and a mounting platform supported and connected by the uniaxial flexible hinge. The driving end of the friction piezoelectric actuator is connected to the mounting platform, and an adjusting gasket is provided between the two.

5. A driving method for a piezoelectric friction driven micro-nano displacement stage according to any one of claims 2 to 4, characterized in that: include: The driving piezoelectric actuator and the friction piezoelectric actuator both use a step-type excitation voltage; when the loading platform performs a forward stroke micro-movement, the driving piezoelectric actuator first applies a step voltage to drive the loading platform to complete a step micro-movement; then, the friction piezoelectric actuator applies a step voltage to drive the driving foot to quickly leave the displacement guide rail, and then the driving piezoelectric actuator voltage is canceled, and the driving piezoelectric actuator shrinks back; finally, after returning to the initial position, the friction piezoelectric actuator voltage is canceled; this is a complete forward step cycle; this cycle is repeated continuously to achieve a forward large stroke displacement of nanometer-level micro-stepping; When the loading platform performs a forward stroke micro-movement, first, the friction piezoelectric actuator applies a step voltage to drive the driving foot to quickly leave the displacement guide rail; then, the driving piezoelectric actuator applies a step voltage to drive the loading platform to perform a step micro-movement retreat; then, the friction piezoelectric actuator voltage is canceled, and the driving foot gradually adheres and connects to the displacement guide rail under the elastic compression of the self-locking spring; finally, the driving piezoelectric actuator voltage is canceled, and the driving piezoelectric actuator contracts to achieve a complete reverse stepping cycle of the loading platform; this cycle is repeated continuously to achieve a reverse large-stroke displacement of nanometer-level micro-stepping.

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