Patch type piezoelectric two-degree-of-freedom mechanical arm and driving method thereof

Abstract

The invention provides a patch type piezoelectric two-degree-of-freedom mechanical arm and a driving method thereof, and relates to the field of piezoelectric driving and robots. The mechanical arm comprises a plurality of unit arm sections which are connected in sequence; each unit arm section comprises two piezoelectric vibrators and two joint parts; the spatial positions of the joint parts of the adjacent unit arm sections are mutually orthogonal, and orthogonal connection between the unit arm sections and application of pre-pressure are achieved through the joint parts between the unit arm sections. The design structure is simple and compact, and miniaturization is easy to realize. The mechanical arm driven based on piezoelectric ceramics does not need to be lubricated by lubricating oil, and is small in size, simple in structure, fast in response, free of electromagnetic interference, capable of achieving power-off self-locking and high in control precision.

Description

Technical Field

[0001] The invention relates to the field of piezoelectric drive and robots, and in particular to a patch-type piezoelectric two-degree-of-freedom mechanical arm and a driving method thereof. Background Art

[0002] As human beings explore space more deeply, the demand for repair, assembly and operation in space is increasing. As a flexible tool, space manipulators can perform various tasks, such as satellite repair, space station assembly, cargo handling, etc., so they have attracted widespread attention. Traditional space manipulators usually use hydraulic or electric motors as the driving source, and realize the movement of the manipulator through hydraulic systems or electric motors. In outer space, the temperature changes greatly and irregularly. Temperature changes may cause materials to expand and contract, thus affecting the structure and performance of the manipulator. Space is almost a vacuum, lacking the support and resistance of the atmosphere, which means that the manipulator will not be affected by air resistance when operating in space, and there is no need to consider problems such as lubricant volatilization and material aging.

[0003] In recent years, piezoelectric-driven robotic arms have gradually emerged. They use the coupling of heterogeneous modes as the driving basis. During the design process, the modal frequency consistency adjustment is required, which is labor-intensive and complicated. In addition, many restrictions are imposed on the geometric shape and size of the structure, making it difficult to achieve serialization and modular design. In addition, the wear of this type of piezoelectric actuator during operation can cause two-phase frequency drift, increase the two-phase frequency difference, and reduce the driving performance of the robotic arm.

[0004] Therefore, in most of the current solutions, it is difficult to achieve miniaturization due to the complex structure of the robotic arm and its lack of compactness. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention provides a patch-type piezoelectric two-degree-of-freedom mechanical arm and a driving method thereof, which has a simple and compact design structure and is easy to realize miniaturization. The mechanical arm driven by piezoelectric ceramics does not require lubrication of lubricating oil, has a small size, a simple structure, a fast response, is not subject to electromagnetic interference, can be self-locked when powered off, and has high control accuracy.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: In the first aspect, an embodiment of the present invention provides a patch-type piezoelectric two-degree-of-freedom mechanical arm, which is composed of at least two unit arm sections connected in sequence, and each unit arm section is connected by a connecting assembly; each unit arm section includes two piezoelectric vibrators and two joint parts; the piezoelectric vibrator includes: a first metal substrate and a piezoelectric drive assembly; holes are punched at both ends of the first metal substrate, and completely symmetrical rectangular patch grooves are provided on both sides of the center of the first metal substrate; the external threads of the two screws at both ends of each unit arm section pass through the gasket and the first circular hole at the piezoelectric vibrator in sequence, and then the piezoelectric vibrator and the joint part are assembled and fixedly connected by the screws and the internal threads on the outside of the stator substrate; the piezoelectric drive assembly is installed from left to right in sequence: a first piezoelectric ceramic sheet, a second piezoelectric ceramic sheet, a third piezoelectric ceramic sheet, and a fourth piezoelectric ceramic sheet; the first metal substrate on each piezoelectric vibrator is grounded, and the second electrode sheet and the first The four electrode sheets input driving signals through the power supply; the joint part is composed of a joint matrix, screws and washers, one of the joint parts at both ends of the unit arm section is equipped with a pressure spring, the joint matrix is ​​a semicircular hoop structure with a special circular cross-section, and through holes are provided on both sides of the joint matrix; the joint part of one end of a unit arm section that is not equipped with a pressure spring is connected to the joint part of one end of the other unit arm section that is equipped with a pressure spring; the joint matrices of the joint parts of the two connected unit arm sections are orthogonally arranged in space, and the pressure spring plays a role in applying pre-pressure; the two orthogonally arranged joint matrices are connected and positioned by screws and washers and fixed to the two piezoelectric vibrators of their respective unit arm sections; the external thread of the screw is matched with the gap of the through hole of the piezoelectric vibrator; the through hole of the piezoelectric vibrator is connected to the internal thread of the hole on the outside of the stator matrix by screws; no thread is required at the hole of the piezoelectric vibrator, and the hole of the joint matrix is ​​provided with an internal thread, which is connected by screws; a rectangular groove corresponding to the pressure spring is provided at the inside of the joint matrix.

[0007] The first piezoelectric ceramic sheet, the second piezoelectric ceramic sheet, the third piezoelectric ceramic sheet and the fourth piezoelectric ceramic sheet are all single-partitioned rectangular piezoelectric ceramic sheets polarized along the thickness direction; in the single-partitioned circular piezoelectric ceramic sheets, the polarization directions of two adjacent piezoelectric ceramic sheets are opposite, and the polarization directions of the two piezoelectric ceramic sheets on both sides of each joint are opposite, that is, if the polarization direction of the first piezoelectric ceramic sheet is positive, the polarization direction of the second piezoelectric ceramic sheet is negative, if the polarization direction of the third piezoelectric ceramic sheet is negative, the polarization direction of the fourth piezoelectric ceramic sheet is positive, and vice versa.

[0008] The first piezoelectric ceramic sheet is bonded to the first rectangular patch groove; the second piezoelectric ceramic sheet is bonded to the second rectangular patch groove; the third piezoelectric ceramic sheet is bonded to the third rectangular patch groove; and the fourth piezoelectric ceramic sheet is bonded to the fourth rectangular patch groove.

[0009] The external threads of the two screws at both ends of the unit arm section pass through the washer and the first circular hole at the piezoelectric vibrator in sequence, and then the piezoelectric vibrator and the joint part are assembled and fixedly connected by the screws and the internal threads on the outside of the stator matrix.

[0010] The piezoelectric drive components are insulated with waterproof glue.

[0011] In a second aspect, an embodiment of the present invention provides a driving process of a patch-type piezoelectric two-degree-of-freedom mechanical arm, including: A simple harmonic driving signal is applied to the first piezoelectric ceramic plate and the second piezoelectric ceramic plate of the piezoelectric driving assembly of the two piezoelectric vibrators on the unit arm section, and a second simple harmonic driving signal with the same frequency as the first simple harmonic driving signal and a time phase difference of π / 2 is applied to the third piezoelectric ceramic plate and the fourth piezoelectric ceramic plate of the unit arm section, so as to stimulate two first-order longitudinal vibration modes of the first and second piezoelectric vibrators that are orthogonal to each other in time and space, so that the unit arm section joint base of the piezoelectric vibrator to which the simple harmonic driving signal is applied and the points where the joint base of the adjacent unit arm section connected in series contacts produce elliptical motion.

[0012] Apply driving signals to two piezoelectric vibrators of adjacent unit arm sections respectively, triggering the rotation of the unit arm sections around the axis direction of the circular cross-section of the contact part of the joint base of the adjacent unit arm section; apply driving signals to the piezoelectric vibrators of the two unit arm sections respectively, triggering the two unit arm sections to rotate in two degrees of freedom in orthogonal planes, wherein the unit arm section and the adjacent unit arm section are orthogonal in space.

[0013] The beneficial effects of the present invention are: 1. In view of the problems of complex structure and low control accuracy of traditional electromagnetic and hydraulic machine driven mechanical arms, the present invention has a compact and simple structure and is easy to realize miniaturization. In addition, the power-off self-locking effect of the piezoelectric driving principle makes the mechanical arm of the present invention have high control accuracy.

[0014] 2. Compared with other piezoelectrically actuated robotic arms, since the piezoelectric vibrator uses the first-order longitudinal vibration single mode as the driving basis, there is no need to adjust the frequency consistency of the special-shaped modes, which reduces the restrictions on the design size and shape of the robotic arm, and is easier to achieve serialized and modular design. In addition, the robotic arm has many adjustable sizes depending on the engineering application scenario, has strong engineering applicability, and has important application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of the structure of a patch-type piezoelectric two-degree-of-freedom mechanical arm provided by an embodiment of the present invention; Figure 2A schematic diagram of a unit arm section structure provided by an embodiment of the present invention; Figure 3 A schematic diagram of a metal substrate of a piezoelectric vibrator provided in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a piezoelectric vibrator provided in an embodiment of the present invention; Figure 5 A schematic diagram of a joint assembly provided by an embodiment of the present invention; Figure 6 A schematic diagram of the structure of a joint part provided by an embodiment of the present invention; Figure 7 A schematic diagram of a voltage signal applied to a piezoelectric drive assembly provided in an embodiment of the present invention; Figure 8 A schematic diagram of the first-order longitudinal vibration mode of a piezoelectric vibrator along the Z axis provided by an embodiment of the present invention; The numbers in the accompanying drawings represent respectively: 1-first unit arm section, 2-second unit arm section, 3-third unit arm section, 4-piezoelectric vibrator, 5-joint part, 4.1-first metal substrate, 4.2-piezoelectric drive component, 4.1.1-first circular hole, 4.1.2-second circular hole, 4.2.1-first piezoelectric ceramic sheet, 4.2.2-second piezoelectric ceramic sheet, 4.2.3-third piezoelectric ceramic sheet, 4.2.4-fourth piezoelectric ceramic sheet, 4.2.5-first rectangular patch slot, 4.2.6-second rectangular patch slot, 4.2.7-third rectangular patch slot, 4.2.8-fourth rectangular patch slot, 5.1-joint substrate, 5.1.1-internal thread of joint substrate through hole, 5.1.2-compression spring slot, 5.2-screw, 5.3-washer, 5.4-compression spring. DETAILED DESCRIPTION

[0017] 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 part of the embodiments of the present invention, not all of the 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.

[0018] Specific as Figure 1 As shown, the present invention discloses a patch-type piezoelectric two-degree-of-freedom robotic arm, comprising a plurality of sequentially connected unit arm segments and connecting components between the arm segments; for the sake of illustration, a two-degree-of-freedom piezoelectric driven robotic arm comprising three unit arm segments is taken as an example, and the three unit arm segments comprised are respectively a first unit arm segment 1, a second unit arm segment 2, and a third unit arm segment 3.

[0019] like Figure 2 As shown, each unit arm segment includes two piezoelectric vibrators 4 and two joint parts 5.

[0020] like Figure 3 Each piezoelectric vibrator 4 shown comprises a first metal substrate 4.1 and a piezoelectric driving component 4.2.

[0021] like Figure 4 As shown, holes are punched at both ends of the first metal substrate 4.1, and completely symmetrical rectangular patch grooves are provided on both sides of the center of the first metal substrate 4.1.

[0022] like Figure 5 The piezoelectric drive assembly 4.2 shown in the figure includes, from left to right, a first piezoelectric ceramic sheet 4.2.1, a second piezoelectric ceramic sheet 4.2.2, a third piezoelectric ceramic sheet 4.2.3, and a fourth piezoelectric ceramic sheet 4.2.4; the first metal substrate 4.1 on each piezoelectric vibrator 4 is grounded; the first to fourth piezoelectric ceramic sheets are all single-partition rectangular piezoelectric ceramic sheets polarized along the thickness direction, and the polarization directions of two adjacent piezoelectric ceramic sheets are opposite, that is, if the polarization direction of the first piezoelectric ceramic sheet 4.2.1 is positive, the polarization direction of the second piezoelectric ceramic sheet is positive. Piezoelectric ceramic piece 4.2.2 is negative. If the polarization direction of the third piezoelectric ceramic piece 4.2.3 is negative, the polarization direction of the fourth piezoelectric ceramic piece 4.2.4 is positive, and vice versa. The first piezoelectric ceramic piece 4.2.1 is bonded to the first rectangular patch groove 4.2.5; the second piezoelectric ceramic piece 4.2.2 is bonded to the second rectangular patch groove 4.2.6; the third piezoelectric ceramic piece 4.2.3 is bonded to the third rectangular patch groove 4.2.7; the fourth piezoelectric ceramic piece 4.2.4 is bonded to the fourth rectangular patch groove 4.2.8.

[0023] like Figure 6 As shown, the joint part 5 is composed of a joint base 5.1, a screw 5.2 and a washer 5.3. One of the joint parts 5 at both ends of the unit arm section is equipped with a pressure spring 5.4. The joint base 5.1 is a semicircular hoop structure with a special-shaped circular cross-section. Through holes are arranged on both sides of the joint base 5.1. The joint part 5 at one end of a unit arm section not equipped with a pressure spring 5.4 is connected to the joint part 5 at one end of another unit arm section equipped with a pressure spring 5.4. The joint bases 5.1 of the joint parts 5 of the two connected unit arm sections are orthogonally arranged in space, and the pressure spring 5.4 plays a role in applying pre-pressure. The two orthogonally arranged joint bases 5.1 are connected and positioned by screws 5.2 and washers 5.3 and fixed to the two piezoelectric vibrators 4 of their respective unit arm sections. The joint bases 5.1 of the joint parts 5 of the two connected unit arm sections are arranged orthogonally in space, and the compression springs 5.4 play a role in applying pre-pressure; Two orthogonally arranged joint bases 5.1 are connected and positioned by screws 5.2 and washers 5.3 and fixed to the two piezoelectric vibrators 4 of the respective unit arm sections; The external thread of the screw 5.2 is matched with the clearance of the through hole of the piezoelectric vibrator 4; the through hole of the piezoelectric vibrator 4 and the internal thread 5.1.1 at the outer hole of the stator base 5.1 are connected through the screw 5.2, and the external threads of the two screws 5.2 located at the two ends of the unit arm section pass through the washer 5.3 and the first circular hole 4.1.1 of the piezoelectric vibrator 4 in turn, and then the piezoelectric vibrator 4 and the joint part 5 are assembled and fixedly connected through the screw 5.2 and the internal thread 5.1.1 on the outer side of the stator base 5.1.

[0024] like Figure 7 As shown, a harmonic driving signal is applied to the first piezoelectric ceramic plate 4.2.1 and the second piezoelectric ceramic plate 4.2.2 of the piezoelectric driving assembly 4.2 of the two piezoelectric vibrators 4 on the unit arm section, and a second harmonic driving signal with the same frequency as the first harmonic driving signal and a time phase difference of π / 2 is applied to the third piezoelectric ceramic plate 4.2.3 and the fourth piezoelectric ceramic plate 4.2.4 of the unit arm section, so as to stimulate two first-order longitudinal vibration modes of the first and second piezoelectric vibrators that are orthogonal to each other in time and space, so that the unit arm section joint base 5.1 of the piezoelectric vibrator 4 to which the harmonic driving signal is applied and the points where the joint base 5.1 of the adjacent unit arm section connected in series are in contact produce elliptical motion.

[0025] Figure 8 A schematic diagram of the first-order longitudinal vibration mode of a piezoelectric vibrator along the Z-axis provided in an embodiment of the present invention.

[0026] Applying driving signals to the two piezoelectric vibrators 4 of the adjacent unit arm sections respectively triggers the rotation of the unit arm sections around the axis direction of the circular cross section of the contact part of the joint base 5.1 of the adjacent unit arm section; applying driving signals to the piezoelectric vibrators 4 of the two unit arm sections respectively triggers the two-degree-of-freedom rotation of the two unit arm sections in the orthogonal plane, wherein the unit arm section and the adjacent unit arm section are orthogonal in space. Since the unit arm section and its adjacent unit arm section are orthogonal in space, applying driving signals to the corresponding piezoelectric vibrators of the two unit arm sections can realize the two-degree-of-freedom rotation of the two unit arm sections in the orthogonal plane.

[0027] In the present embodiment, a patch-type piezoelectric two-degree-of-freedom mechanical arm and a driving method thereof are disclosed, wherein the mechanical arm comprises a plurality of sequentially connected unit arm sections and connection components between the arm sections; each unit arm section comprises two piezoelectric vibrators 4 and a joint portion 5; the spatial positions of the joint portions 5 of each unit arm section and the adjacent unit arm section are mutually orthogonal, and two orthogonally arranged joint bases 5.1 are connected and positioned by screws 5.2 and washers 5.3 and fixed to the two piezoelectric vibrators 4 of their respective unit arm sections, and a compression spring 5.4 serves to apply pre-pressure; during operation, the simple harmonic driving signal applied to the two piezoelectric vibrators of the same unit arm section is a simple harmonic driving signal of a specific frequency with a time phase difference of π / 2, wherein the specific frequency is a preset The frequency value can simultaneously excite the first-order longitudinal vibration mode of the two piezoelectric vibrators 4 with a phase difference of π / 2 in time, so that the points where the unit arm section joint matrix 5.1 of the piezoelectric vibrator 4 to which the simple harmonic driving signal is applied and the joint matrix 5.1 of the adjacent unit arm section in series produce a slight elliptical motion, and a driving force is generated through the friction effect. The driving signal is applied to the two piezoelectric vibrators 4 of the adjacent unit arm sections, respectively, and the rotation of the unit arm section around the axis direction of the circular section of the contact part of the joint matrix 5.1 of the adjacent unit arm section is triggered. Since the unit arm section and its adjacent unit arm section are orthogonal in space, the corresponding piezoelectric vibrators are applied with the driving signal to the two unit arm sections, so that the two unit arm sections can realize the two-degree-of-freedom rotation of the two unit arm sections in the orthogonal plane.

[0028] The piezoelectric vibrator 4 of the present invention uses the first-order longitudinal vibration single mode as the driving basis, and there is no need to adjust the frequency consistency of the special-shaped mode, which reduces the restrictions on the design size and shape of the robot arm, and is easier to achieve serialized and modular design. It has important application prospects in different engineering applications.

[0029] Compared with the prior art, this embodiment has the following advantages: Compared with traditional electromagnetic and hydraulic machine-driven mechanical arms, it has a simple structure, light weight, no need for gear reduction mechanisms, is easy to seal, easy to achieve miniaturization, has low operating noise, is easy to achieve low-speed and high torque, is not affected by electromagnetic interference, can self-lock when power is off, and has high control accuracy.

[0030] Compared with other piezoelectrically actuated robotic arms, since the piezoelectric vibrator 4 uses the first-order longitudinal vibration single mode as the driving basis, there is no need to adjust the modal coupling frequency consistency of different phase modes, which reduces the restrictions on the design size and shape of the robotic arm, and is easier to achieve serialized and modular design. Moreover, depending on the engineering application scenario, the robotic arm has many adjustable sizes, strong engineering applicability, and important application prospects.

[0031] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, the above is only a preferred embodiment of the present invention. Since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field is within the technical scope disclosed by the present invention. For ordinary technicians in the technical field, changes or replacements that can be easily thought of should be covered within the protection scope of the present invention without departing from the principle of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A patch-type piezoelectric two-degree-of-freedom robotic arm, characterized in that: It comprises at least two sequentially connected unit arm sections, wherein adjacent unit arm sections are connected via joint sections (5), and each unit arm section comprises two piezoelectric vibrators (4) and two joint sections (5) respectively located at two ends of the piezoelectric vibrators; The piezoelectric vibrator (4) comprises a first metal substrate (4.1) and a piezoelectric drive component (4.2); two sides of the center of the first metal substrate (4.1) are provided with completely symmetrical rectangular patch grooves; the piezoelectric drive components (4.2) are installed in the rectangular patch grooves; the piezoelectric drive components (4.2) installed in sequence from left to right on a unit arm section are respectively a first piezoelectric ceramic piece (4.2.1), a second piezoelectric ceramic piece (4.2.2), a third piezoelectric ceramic piece (4.2.3), and a fourth piezoelectric ceramic piece (4.2.4); The joint part (5) is a joint base (5.1) with a semicircular hoop structure of a special-shaped circular cross-section. Through holes are provided at two ear plates of the joint base (5.1). The piezoelectric vibrator (4) is fixedly connected to the joint bases (5.1) at both ends via screws (5.2) and washers (5.3). One of the joint parts (5) at both ends of the unit arm section is provided with a pressure spring (5.4). A rectangular groove (5.1.2) corresponding to the pressure spring (5.4) is provided on the inner side of the joint base (5.1). In two adjacent unit arm sections, the joint part (5) at one end without the pressure spring (5.4) is connected to the joint part (5) at one end of the other unit arm section provided with the pressure spring (5.4). The joint bases (5.1) of the joint parts (5) of the two connected unit arm sections are orthogonally arranged in space, and the pressure spring (5.4) applies pre-pressure to the two joint bases (5.1).

2. The patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 1, characterized in that: The first metal substrate (4.1) is a completely axisymmetric structure; a first circular hole (4.1.1) and a second circular hole (4.1.2) are respectively formed at two ends of the first metal substrate (4.1); the first circular hole (4.1.1) and the second circular hole (4.1.2) have completely the same aperture diameter and depth; the first rectangular patch slot (4.2.5) and the second rectangular patch slot (4.2.6) have completely the same size and are located at the center of the first metal substrate (4.1).

3. The patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 1, characterized in that: The first piezoelectric ceramic sheet (4.2.1), the second piezoelectric ceramic sheet (4.2.2), the third piezoelectric ceramic sheet (4.2.3) and the fourth piezoelectric ceramic sheet (4.2.4) are all single-partition rectangular piezoelectric ceramic sheets polarized along the thickness direction, wherein the two piezoelectric ceramic sheets on both sides of each joint have opposite polarization directions.

4. The patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 3, characterized in that: The four rectangular patch slots on the unit arm section from left to right are the first rectangular patch slot (4.2.5), the second rectangular patch slot (4.2.6), the third rectangular patch slot (4.2.7), and the fourth rectangular patch slot (4.2.8); The first piezoelectric ceramic sheet (4.2.1) is bonded to the first rectangular patch groove (4.2.5); The second piezoelectric ceramic sheet (4.2.2) is bonded to the second rectangular patch groove (4.2.6); The third piezoelectric ceramic sheet (4.2.3) is bonded to the third rectangular patch groove (4.2.7); The fourth piezoelectric ceramic sheet (4.2.4) is bonded to the fourth rectangular patch groove (4.2.8).

5. The patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 1, characterized in that: The external threads of the two screws (5.2) located at the two ends of the unit arm section pass through the washer (5.3) and the first circular hole (4.1.1) at the piezoelectric vibrator (4) in sequence, and then the piezoelectric vibrator (4) and the joint part (5) are assembled and fixedly connected by the screws (5.2) and the internal threads (5.1.1) of the through holes on the outside of the stator base (5.1).

6. The patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 1, characterized in that: The piezoelectric drive component (4.2) is insulated using waterproof glue.

7. A method for driving the patch-type piezoelectric two-degree-of-freedom mechanical arm as claimed in any one of claims 1 to 6, characterized in that The following steps are involved: A first simple harmonic driving signal is applied to the first piezoelectric ceramic plate (4.2.1) and the second piezoelectric ceramic plate (4.2.2) of the piezoelectric driving components (4.2) of the two piezoelectric vibrators (4) on the unit arm section, and a second simple harmonic driving signal having the same frequency as the first simple harmonic driving signal and a time phase difference of π / 2 is applied to the third piezoelectric ceramic plate (4.2.3) and the fourth piezoelectric ceramic plate (4.2.4) of the unit arm section, so as to stimulate two first-order longitudinal vibration modes of the first and second piezoelectric vibrators that are mutually orthogonal in time and space, so that each point where the unit arm section joint base (5.1) of the piezoelectric vibrator (4) to which the simple harmonic driving signal is applied contacts with the joint base (5.1) of the adjacent unit arm section connected in series generates an elliptical motion.

8. The driving method of the patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 8, characterized in that: The simple harmonic driving signal applied to the two piezoelectric vibrators of the same unit arm section is a simple harmonic driving signal of a specific frequency with a time phase difference of π / 2, wherein the specific frequency is a preset frequency value, and simultaneously stimulates the two piezoelectric vibrators (4) to have a first-order longitudinal vibration mode with a time phase difference of π / 2.

9. The driving method of the patch-type piezoelectric two-degree-of-freedom mechanical arm according to claim 8, characterized in that: A driving signal is applied to two piezoelectric vibrators (4) of adjacent unit arm sections respectively, triggering the rotation of the unit arm sections around the axis direction of the circular cross section of the contact portion of the joint base (5.1) of the adjacent unit arm section; a driving signal is applied to the piezoelectric vibrators (4) of the two unit arm sections respectively, triggering the two unit arm sections to rotate in two degrees of freedom in an orthogonal plane, wherein the unit arm section and the adjacent unit arm section are orthogonal in space.

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