A single-degree-of-freedom piezoelectric inchworm driver and its excitation method

Abstract

The present disclosure provides a single-degree-of-freedom piezoelectric inchworm driver and an excitation method thereof, belonging to the field of piezoelectric drive technology. The single-degree-of-freedom piezoelectric inchworm driver includes two parts, a rotor and a stator. The stator is divided into an upper, middle and lower three-layer structure, and is composed of two annular bases, six piezoelectric stacks, four clamps, four wedges, four flexible hinges, ten hexagon socket head screws and an annular gasket. By designing the excitation voltage signal applied to the piezoelectric stack, controlling its timing and amplitude, the upper clamping unit of the stator is excited to rotate, thereby driving the rotor to rotate. The single-degree-of-freedom piezoelectric inchworm driver has the advantages of large stroke, high precision, large torque and fast response speed, and has broad application prospects in the fields of micro-nano positioning, ultra-tight machining, scanning probe microscope (SPM) systems, etc.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of piezoelectric actuators, and in particular, relates to a single-degree-of-freedom piezoelectric inchworm actuator and an excitation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] As a piezoelectric micro-turntable driving device, the piezoelectric driver overcomes the shortcomings of previous mechanical, hydraulic, pneumatic, electromagnetic and other drivers, such as large inertia, slow response, complex structure, and poor reliability. It greatly reduces the size of the turntable and greatly improves the bearing capacity. It also has the advantages of high resolution, no noise, and no heat.

[0004] Piezoelectric drivers can be mainly divided into ultrasonic drivers, inertial stepper drivers, inchworm drivers, and the like. Ultrasonic drivers are piezoelectric vibrators based on elliptical motion. Under the action of friction, the driver can reach very high speeds, but it is still difficult to make both the output force and speed very high. Inertial stepper drivers usually consist of only one motion, so they are easy to control and have a fast response speed. Inchworm drivers usually have a large range of motion and high output. The inventors have found that most inchworm drivers are linear drivers that only use the inchworm principle to provide a small amount of rotational drive. They have a limited drive range and have difficulties in outputting torque. In addition, the driver structure is relatively complex and the motion accuracy is low. Summary of the invention

[0005] In order to solve the above problems, the present disclosure provides a single-degree-of-freedom piezoelectric inchworm driver and an excitation method thereof, which has the advantages of large stroke, high precision, large torque and fast response speed.

[0006] According to a first aspect of the embodiments of the present disclosure, a single-degree-of-freedom piezoelectric inchworm actuator is provided, comprising: a rotor and a stator, wherein the stator is composed of three layers: an upper layer, a middle layer, and a lower layer; wherein:

[0007] The upper structure includes a clamping unit, an adjustment unit and a driving unit for clamping the rotor; the adjustment unit adjusts the wedge block through a pre-tightening screw to achieve the regulation of the clamping unit's clamping force on the rotor; the driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base, and the upper base is provided with a plurality of axial threaded holes;

[0008] The lower structure includes a normally closed clamping unit, which is composed of two piezoelectric stacks, two clamps and a lower base. The piezoelectric stack is arranged in a groove of the clamp, and the two piezoelectric stacks and the two clamps are respectively axially symmetrically distributed about the rotor, and a plurality of axial threaded holes are symmetrically distributed on the lower base;

[0009] The middle structure is an annular gasket disposed between the upper structure and the lower structure, and the annular gasket is provided with an axial through hole;

[0010] The axial threaded holes of the upper structure, the axial threaded holes of the lower structure and the axial through holes of the middle structure are in the same vertical direction, and the upper, middle and lower structures are connected and fixed by screws.

[0011] Furthermore, the clamping unit includes two clamps and two piezoelectric stacks, and the clamping units are symmetrically distributed in the groove at the rotation center of the upper structure.

[0012] Furthermore, the adjustment unit includes four wedges and two pre-tightening screws. The four wedges are fitted in pairs and distributed on both sides of the rotor. The adjustment of the wedges is achieved by the pre-tightening screws respectively arranged on both sides of the rotation center.

[0013] Furthermore, the driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base. Radial threaded holes are arranged on both sides of the rotation center. The rotation center is connected to the upper base through four flexible hinges, and the four flexible hinges are symmetrically distributed on both sides of the rotor. The two piezoelectric stacks are respectively arranged in the grooves of the upper base and are symmetrically distributed about the center of the rotor.

[0014] Furthermore, four axial threaded holes are symmetrically arranged on the upper base, and the angle between two adjacent axial threaded holes is 90 degrees.

[0015] Furthermore, the plurality of axial threaded holes are symmetrically distributed on the lower base, specifically: eight axial threaded holes are symmetrically arranged on the lower base, and the angle between two adjacent axial threaded holes is 45 degrees.

[0016] Furthermore, the two clamps in the normally closed clamping unit of the lower structure clamp the rotor when the piezoelectric stack is not powered.

[0017] According to a second aspect of an embodiment of the present disclosure, a method for exciting a single-degree-of-freedom piezoelectric inchworm actuator is provided. The method is based on the above-mentioned single-degree-of-freedom piezoelectric inchworm actuator and includes:

[0018] Step 1: Apply a high excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks extend, and the two clamps clamp the rotor;

[0019] Step 2: Apply a high excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks extend, and the two clamps thereof release the rotor;

[0020] Step 3: Apply a high excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks extend, and the piezoelectric stacks of the driving unit push the rotation center to rotate the rotor by a certain angle;

[0021] Step 4: applying a low excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks are de-energized and contracted, and the two clamps clamp the rotor;

[0022] Step 5: Apply a low excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks contract, and the two clamps release the rotor;

[0023] Step 6: Apply a low excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks are powered off and contracted, and the rotation center is restored to its original position under the action of the flexible hinge;

[0024] Execute steps 1 to 6 to achieve a working cycle.

[0025] Furthermore, in step 1, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a low excitation voltage signal state, the two piezoelectric stacks are not extended, the two clamps clamp the rotor, and the two piezoelectric stacks of the driving unit are both in a low excitation voltage signal state, and the piezoelectric stacks are not extended;

[0026] Or, in step 2, the two piezoelectric stacks of the upper structure clamping unit are still in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are in a low excitation voltage signal state;

[0027] Or, in step 3, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a high excitation voltage signal state, and the two piezoelectric stacks of the clamping unit of the upper structure are also in a high excitation voltage signal state.

[0028] Furthermore, in step 4, the two piezoelectric stacks of the upper structure clamping unit are in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are also in a high excitation voltage signal state;

[0029] Or, in step 5, the two piezoelectric stacks of the lower normally closed clamping unit VI are still in a low excitation voltage signal state, and the two piezoelectric stacks of the driving unit are still in a high excitation voltage signal state.

[0030] Or, in step 6, the two piezoelectric stacks of the upper structure clamping unit are still in a low excitation voltage signal state, and the two piezoelectric stacks of the lower structure normally closed clamping unit are also in a low excitation voltage signal state.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The present disclosure provides a single-degree-of-freedom piezoelectric inchworm driver and an excitation method thereof, the scheme can realize the single-degree-of-freedom rotational motion of the rotor; the driver adopts a three-layer structural design, the structure is compact and reliable, and has the advantages of large stroke, high precision, large torque, fast response speed, etc.; at the same time, the upper adjustment unit of the driver can fine-tune the positions of the two clamps well, so that the clamps can better clamp and loosen the rotor under the action of the piezoelectric stack; the design of the lower normally closed clamping unit enables the two clamps to clamp the rotor when the lower piezoelectric stack is not powered on, thereby avoiding movement and damage of the rotor due to other factors when the driver is powered off.

[0033] Advantages of additional aspects of the present disclosure will be given in part in the following description and in part will become apparent from the following description or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0035] Figure 1 Schematic diagram of the overall structure of the piezoelectric inchworm driver described in the embodiment of the present disclosure;

[0036] Figure 2 Schematic diagram of the lower structure of the piezoelectric inchworm driver described in the embodiment of the present disclosure;

[0037] Figure 3 It is a schematic diagram of the middle annular gasket of the piezoelectric inchworm driver described in the embodiment of the present disclosure;

[0038] Figure 4 Schematic diagram of the design principle of the piezoelectric inchworm driver described in the embodiment of the present disclosure;

[0039] Figure 5 Schematic diagram of the excitation voltage signal of the piezoelectric inchworm driver described in the embodiment of the present disclosure;

[0040] Among them, 1, rotor, 2, connecting screw, 3-1, upper clamp, 3-2, upper clamping unit piezoelectric stack, 4-1, wedge, 4-2, pre-tightening screw, 5-1, rotation center, 5-2, flexible hinge, 5-3, drive unit piezoelectric stack, 5-4, upper base; 6-1, lower normally closed clamping unit VI piezoelectric stack, 6-2, lower clamp, 6-3, lower base; 7, annular gasket; I, rotor, III, upper clamping unit, VI, lower normally closed clamping unit; V1 represents the excitation voltage signal applied to the piezoelectric stack of the upper clamping unit, V2 represents the excitation voltage signal applied to the piezoelectric stack of the lower normally closed clamping unit VI, V eRepresents the excitation voltage signal applied to the piezoelectric stack of the drive unit. DETAILED DESCRIPTION

[0041] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0042] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0045] Embodiment 1:

[0046] The purpose of this embodiment is to provide a single-degree-of-freedom piezoelectric inchworm actuator.

[0047] A single-degree-of-freedom piezoelectric inchworm driver comprises: a rotor and a stator, wherein the stator is composed of three layers: an upper layer, a middle layer and a lower layer; wherein:

[0048] The upper structure includes a clamping unit, an adjustment unit and a driving unit for clamping the rotor; the adjustment unit adjusts the wedge block through a pre-tightening screw to achieve the regulation of the clamping unit's clamping force on the rotor; the driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base, and the upper base is provided with a plurality of axial threaded holes;

[0049] The lower structure includes a normally closed clamping unit, which is composed of two piezoelectric stacks, two clamps and a lower base. The piezoelectric stack is arranged in a groove of the clamp, and the two piezoelectric stacks and the two clamps are respectively axially symmetrically distributed about the rotor, and a plurality of axial threaded holes are symmetrically distributed on the lower base;

[0050] The middle structure is an annular gasket disposed between the upper structure and the lower structure, and the annular gasket is provided with an axial through hole;

[0051] The axial threaded holes of the upper structure, the axial threaded holes of the lower structure and the axial through holes of the middle structure are in the same vertical direction, and the upper, middle and lower structures are connected and fixed by screws.

[0052] Furthermore, the clamping unit includes two clamps and two piezoelectric stacks, and the clamping units are symmetrically distributed in the groove at the rotation center of the upper structure.

[0053] Furthermore, the adjustment unit includes four wedges and two pre-tightening screws. The four wedges are fitted in pairs and distributed on both sides of the rotor. The adjustment of the wedges is achieved by the pre-tightening screws respectively arranged on both sides of the rotation center.

[0054] Furthermore, the driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base. Radial threaded holes are arranged on both sides of the rotation center. The rotation center is connected to the upper base through four flexible hinges, and the four flexible hinges are symmetrically distributed on both sides of the rotor. The two piezoelectric stacks are respectively arranged in the grooves of the upper base and are symmetrically distributed about the center of the rotor.

[0055] Furthermore, four axial threaded holes are symmetrically arranged on the upper base, and the angle between two adjacent axial threaded holes is 90 degrees.

[0056] Furthermore, the plurality of axial threaded holes are symmetrically distributed on the lower base, specifically: eight axial threaded holes are symmetrically arranged on the lower base, and the angle between two adjacent axial threaded holes is 45 degrees.

[0057] Furthermore, the two clamps in the normally closed clamping unit of the lower structure clamp the rotor when the piezoelectric stack is not powered.

[0058] Specifically, for ease of understanding, the solution described in this embodiment is described in detail below with reference to the accompanying drawings:

[0059] like Figures 1 to 3As shown, a single-degree-of-freedom piezoelectric inchworm driver includes two parts, a rotor and a stator. The stator is divided into three layers: an upper layer, a middle layer, and a lower layer. The upper layer structure of the stator is mainly composed of three parts: a clamping unit III, an adjustment unit IV, and a driving unit. The clamping unit III is composed of two clamps 3-1 and two piezoelectric stacks 3-2, which are symmetrically distributed in a groove of a rotation center 5-1 at 180°. The adjustment unit IV is composed of four wedges 4-1 and two pre-tightening screws 4-2. The four wedges 4-1 are fitted in pairs and distributed On both sides of the rotor I, each screw 4-2 is arranged on one side of the rotation center 5-1, and is centrally symmetrically distributed; the drive unit consists of a rotation center 5-1, four flexible hinges 5-2, two piezoelectric stacks 5-3 and an upper base 5-4, and the two radial threaded holes on the rotation center 5-1 are distributed on both sides, and are centrally symmetrically distributed. The rotation center 5-1 and the upper base 5-4 are connected by four flexible hinges 5-2, and the four flexible hinges 5-2 are symmetrically distributed on both sides of the rotor I. On the side, the two piezoelectric stacks 5-3 are respectively arranged in the grooves of the upper base 5-4, and are symmetrically distributed about the center of the rotor I. The four axial threaded holes are evenly distributed on the upper base, and the angle between two adjacent holes is 90 degrees; the lower structure is mainly composed of a normally closed clamping unit VI, which is composed of two piezoelectric stacks 6-1, two clamps 6-2 and a lower base 6-3. The two piezoelectric stacks 6-1 are arranged in the grooves of the two clamps 6-2. The two piezoelectric stacks 6-1 and the two clamps 6-2 They are symmetrically distributed about the rotor, and the eight axial threaded holes are symmetrically distributed on the lower base 6-3, and the angle between two adjacent axial threaded holes is 45 degrees; between the upper and lower layers is an annular gasket Ⅶ, and four axial through holes are arranged on the annular gasket Ⅶ, and the angle between two adjacent axial through holes is 90 degrees; the four radial threaded holes, four axial threaded holes and four axial through holes are in the same vertical direction, and four hexagon socket cylindrical head screws II connect and fix the upper, middle and lower three-layer structure, and the angle between adjacent screws II is 90 degrees.

[0060] Furthermore, the two clamps of the normally closed clamping unit VI of the lower layer of the stator clamp the rotor when the lower layer of the piezoelectric stack is not powered, thereby preventing the rotor I from moving and being damaged due to other factors when the drive is powered off.

[0061] Furthermore, one excitation voltage signal is used to control the two piezoelectric stacks of the upper clamping unit III of the stator to control the two clamps to clamp and release the rotor I; a second excitation voltage signal is used to control the two piezoelectric stacks of the driving unit to push the rotation center to produce a small displacement; a third excitation voltage signal is used to control the piezoelectric stack of the normally closed clamping unit VI of the lower stator to control the clamps to loosen and clamp the rotor I.

[0062] Furthermore, by changing the magnitude of the excitation voltage applied to the two piezoelectric stacks of the driver driving unit, the elongation of the piezoelectric stack under the action of the excitation voltage can be changed, thereby adjusting the step angle of the rotor I in a working cycle.

[0063] Further, such as Figure 4 As shown, this embodiment illustrates the driving principle of the single-degree-of-freedom piezoelectric inchworm driver. Through the principle of clamping-driving-clamping, the rotor I is rotated by a step angle in one working cycle, and then the rotor can achieve continuous rotation.

[0064] Embodiment 2:

[0065] The purpose of this embodiment is to provide an excitation method for a single-degree-of-freedom piezoelectric inchworm actuator.

[0066] A method for exciting a single-degree-of-freedom piezoelectric inchworm actuator, based on the above-mentioned single-degree-of-freedom piezoelectric inchworm actuator, comprises:

[0067] Step 1: Apply a high excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks extend, and the two clamps clamp the rotor;

[0068] Step 2: Apply a high excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks extend, and the two clamps thereof release the rotor;

[0069] Step 3: Apply a high excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks extend, and the piezoelectric stacks of the driving unit push the rotation center to rotate the rotor by a certain angle;

[0070] Step 4: applying a low excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks are de-energized and contracted, and the two clamps clamp the rotor;

[0071] Step 5: Apply a low excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks contract, and the two clamps release the rotor;

[0072] Step 6: Apply a low excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks are powered off and contracted, and the rotation center is restored to its original position under the action of the flexible hinge;

[0073] Execute steps 1 to 6 to achieve a working cycle.

[0074] Furthermore, in step 1, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a low excitation voltage signal state, the two piezoelectric stacks are not extended, the two clamps clamp the rotor, and the two piezoelectric stacks of the driving unit are both in a low excitation voltage signal state, and the piezoelectric stacks are not extended;

[0075] Or, in step 2, the two piezoelectric stacks of the upper structure clamping unit are still in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are in a low excitation voltage signal state;

[0076] Or, in step 3, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a high excitation voltage signal state, and the two piezoelectric stacks of the clamping unit of the upper structure are also in a high excitation voltage signal state.

[0077] Furthermore, in step 4, the two piezoelectric stacks of the upper structure clamping unit are in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are also in a high excitation voltage signal state;

[0078] Or, in step 5, the two piezoelectric stacks of the lower normally closed clamping unit VI are still in a low excitation voltage signal state, and the two piezoelectric stacks of the driving unit are still in a high excitation voltage signal state.

[0079] Or, in step 6, the two piezoelectric stacks of the upper structure clamping unit are still in a low excitation voltage signal state, and the two piezoelectric stacks of the lower structure normally closed clamping unit are also in a low excitation voltage signal state.

[0080] For ease of understanding, the solution described in this embodiment is described in detail below with reference to the accompanying drawings:

[0081] like Figure 5 As shown, an excitation method of a single-degree-of-freedom piezoelectric inchworm actuator is used to excite the movement of two piezoelectric stacks of the upper clamping unit III, two piezoelectric stacks of the driving unit, and two piezoelectric stacks of the lower normally closed clamping unit VI, thereby realizing the rotation movement of the rotor I in the clockwise or counterclockwise direction around the Z-axis direction:

[0082] The specific process of driving the rotor I to rotate clockwise around the Z axis is as follows (Note: the low excitation voltage signal is 0 voltage):

[0083] In the initial state, the driver is not powered on, and the piezoelectric stack of the upper clamping unit III, the driving unit, and the lower normally closed clamping unit VI of the driver are not extended. Therefore, the two clamps (3-1) of the upper clamping unit III are in a relaxed state, loosening the rotor I, and the two clamps (two clamps) of the lower normally closed clamping unit VI are in a clamped state, clamping the rotor I.

[0084] Step 1: Apply a high excitation voltage signal to the two piezoelectric stacks (3-2) of the upper clamping unit III of the driver, the two piezoelectric stacks (3-2) extend, and push the two clamps (3-1) to clamp the rotor I; the two piezoelectric stacks (6-1) of the lower normally closed clamping unit VI are in a low excitation voltage signal state, the two piezoelectric stacks (6-1) are not extended, and the lower clamps (6-2) clamp the rotor I; the two piezoelectric stacks (5-3) of the driving unit are in a low excitation voltage signal state, and the piezoelectric stacks (5-3) are not extended.

[0085] Step 2: Apply a high excitation voltage signal to the two piezoelectric stacks (6-1) of the normally closed clamping unit VI of the lower layer of the driver, the piezoelectric stack (6-1) stretches, and the two clamps (6-2) of the lower layer relax the rotor I; the two piezoelectric stacks (3-2) of the upper layer clamping unit III are still in a high excitation voltage signal state, and the two piezoelectric stacks (5-3) of the driving unit are in a low excitation voltage signal state.

[0086] Step 3: A high excitation voltage signal is applied to the two piezoelectric stacks (5-3) of the driver driving unit. The piezoelectric stack (5-3) stretches under the action of the voltage. The rotation center (5-1) and the upper base (5-4) are connected by a flexible hinge. The flexible hinge (5-2) acts as a torsion spring and a spring. Therefore, the piezoelectric stack (5-3) of the driving unit will push the rotation center (5-1) to make the rotor I rotate a certain angle. At this time, the two piezoelectric stacks (6-1) of the lower normally closed clamping unit VI are still in a high excitation voltage signal state, and the two piezoelectric stacks (3-2) of the upper clamping unit III are still in a high excitation voltage signal state.

[0087] Step 4: Apply a low excitation voltage signal to the two piezoelectric stacks (6-1) of the normally closed clamping unit VI of the lower layer of the driver, the piezoelectric stack (6-1) is de-energized and contracts, and the lower clamp (6-2) clamps the rotor I; the two piezoelectric stacks (3-2) of the upper clamping unit III are still in a high excitation voltage signal state, and the two piezoelectric stacks (5-3) of the driving unit are still in a high excitation voltage signal state.

[0088] Step 5: Apply a low excitation voltage signal to the two piezoelectric stacks (3-2) of the upper clamping unit III of the driver, the piezoelectric stack (3-2) contracts, and the clamp (3-1) relaxes the rotor I; the two piezoelectric stacks (6-1) of the lower normally closed clamping unit VI are still in a low excitation voltage signal state, and the two piezoelectric stacks (5-3) of the driving unit are still in a high excitation voltage signal state.

[0089] Step 6: Apply a low excitation voltage signal to the two piezoelectric stacks (5-3) of the driver unit of the driver, the piezoelectric stack (5-3) is de-energized and shrinks, and under the action of the flexible hinge (5-2), the rotation center (5-1) will return to its original position; the two piezoelectric stacks (3-2) of the upper clamping unit III are still in a low excitation voltage signal state, and the two piezoelectric stacks (6-1) of the lower normally closed clamping unit VI are still in a low excitation voltage signal state.

[0090] After the six steps are completed, that is, a working cycle is completed, the rotor I rotates a step angle, and this operation is repeated to achieve continuous rotation. If the sequence of the high and low excitation voltage signals applied to the two piezoelectric stacks (3-2) of the upper clamping unit III of the driver and the two piezoelectric stacks (6-1) of the lower normally closed clamping unit VI are swapped, the rotor I will rotate in the opposite direction. This working principle is the application of the inchworm principle in the new piezoelectric driver.

[0091] The present invention provides a single-degree-of-freedom piezoelectric inchworm driver and an excitation method thereof. The overall structure is divided into three layers: upper, middle and lower. By adopting the clamp-drive-clamp working principle, continuous rotation of the rotor is achieved, and it has the advantages of large stroke, high precision, large torque and fast response speed. It has broad prospects in the fields of micro-nano positioning, ultra-tight machining, scanning probe microscope (SPM) systems, etc.

[0092] The single-degree-of-freedom piezoelectric inchworm driver and the excitation method thereof provided in the above-mentioned embodiment can be realized and have broad application prospects.

[0093] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A single-degree-of-freedom piezoelectric inchworm actuator, characterized in that: include: The rotor and the stator are composed of three layers: upper, middle and lower; wherein, The upper structure includes a clamping unit, an adjustment unit and a driving unit for clamping the rotor; the adjustment unit adjusts the wedge block through a pre-tightening screw to achieve the regulation of the clamping unit's clamping force on the rotor; the driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base, and the upper base is provided with a plurality of axial threaded holes; The lower structure includes a normally closed clamping unit, which is composed of two piezoelectric stacks, two clamps and a lower base. The piezoelectric stack is arranged in a groove of the clamp, and the two piezoelectric stacks and the two clamps are respectively axially symmetrically distributed about the rotor, and a plurality of axial threaded holes are symmetrically distributed on the lower base; The middle structure is an annular gasket disposed between the upper structure and the lower structure, and the annular gasket is provided with an axial through hole; The axial threaded holes of the upper structure, the axial threaded holes of the lower structure and the axial through holes of the middle structure are in the same vertical direction, and the upper, middle and lower structures are connected and fixed by screws.

2. A single-degree-of-freedom piezoelectric inchworm actuator as claimed in claim 1, characterized in that: The clamping unit includes two clamps and two piezoelectric stacks, and the clamping units are symmetrically distributed in the groove at the rotation center of the upper structure.

3. A single-degree-of-freedom piezoelectric inchworm actuator as claimed in claim 1, characterized in that: The adjustment unit includes four wedges and two pre-tightening screws. The four wedges are fitted in pairs and distributed on both sides of the rotor. The adjustment of the wedges is achieved by the pre-tightening screws respectively arranged on both sides of the rotation center.

4. A single-degree-of-freedom piezoelectric inchworm actuator as claimed in claim 1, characterized in that: The driving unit includes a rotation center, four flexible hinges, two piezoelectric stacks and an upper base. Radial threaded holes are arranged on both sides of the rotation center. The rotation center is connected to the upper base through four flexible hinges, and the four flexible hinges are symmetrically distributed on both sides of the rotor. The two piezoelectric stacks are respectively arranged in the grooves of the upper base and are symmetrically distributed about the center of the rotor.

5. The single-degree-of-freedom piezoelectric inchworm actuator according to claim 1, characterized in that: Four axial threaded holes are symmetrically arranged on the upper base, and the angle between two adjacent axial threaded holes is 90 degrees.

6. A single-degree-of-freedom piezoelectric inchworm actuator as claimed in claim 1, characterized in that: The plurality of axial threaded holes are symmetrically distributed on the lower base. Specifically, eight axial threaded holes are symmetrically arranged on the lower base, and the angle between two adjacent axial threaded holes is 45 degrees.

7. A single-degree-of-freedom piezoelectric inchworm actuator as claimed in claim 1, characterized in that: Two clamps in the normally closed clamping unit of the lower structure clamp the rotor when the piezoelectric stack is not energized.

8. A method for exciting a single-degree-of-freedom piezoelectric inchworm actuator, based on a single-degree-of-freedom piezoelectric inchworm actuator according to any one of claims 1 to 7, comprising: Step 1: Apply a high excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks extend, and the two clamps clamp the rotor; Step 2: Apply a high excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks extend, and the two clamps thereof release the rotor; Step 3: Apply a high excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks extend, and the piezoelectric stacks of the driving unit push the rotation center to rotate the rotor by a certain angle; Step 4: applying a low excitation voltage signal to the two piezoelectric stacks of the normally closed clamping unit of the lower structure, the piezoelectric stacks are de-energized and contracted, and the two clamps clamp the rotor; Step 5: Apply a low excitation voltage signal to the two piezoelectric stacks of the upper structure clamping unit, the piezoelectric stacks contract, and the two clamps release the rotor; Step 6: Apply a low excitation voltage signal to the two piezoelectric stacks of the driving unit, the piezoelectric stacks are powered off and contracted, and the rotation center is restored to its original position under the action of the flexible hinge; Execute steps 1 to 6 to achieve a working cycle.

9. The excitation method of a single-degree-of-freedom piezoelectric inchworm actuator according to claim 8, characterized in that: In the step 1, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a low excitation voltage signal state, the two piezoelectric stacks are not extended, the two clamps clamp the rotor, and the two piezoelectric stacks of the driving unit are both in a low excitation voltage signal state, and the piezoelectric stacks are not extended; Or, in step 2, the two piezoelectric stacks of the upper structure clamping unit are still in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are in a low excitation voltage signal state; Or, in step 3, the two piezoelectric stacks of the normally closed clamping unit of the lower structure are in a high excitation voltage signal state, and the two piezoelectric stacks of the clamping unit of the upper structure are also in a high excitation voltage signal state.

10. The excitation method of a single-degree-of-freedom piezoelectric inchworm actuator according to claim 8, characterized in that: In step 4, the two piezoelectric stacks of the upper structure clamping unit are in a high excitation voltage signal state, and the two piezoelectric stacks of the driving unit are also in a high excitation voltage signal state; Or, in step 5, the two piezoelectric stacks of the lower normally closed clamping unit VI are still in a low excitation voltage signal state, and the two piezoelectric stacks of the driving unit are still in a high excitation voltage signal state; Or, in step 6, the two piezoelectric stacks of the upper structure clamping unit are still in a low excitation voltage signal state, and the two piezoelectric stacks of the lower structure normally closed clamping unit are also in a low excitation voltage signal state.

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