Mobile robot based on multi-degree-of-freedom piezoelectric actuator and its excitation method

Abstract

The present invention discloses a mobile robot based on a multi-degree-of-freedom piezoelectric actuator and an excitation method thereof, wherein the piezoelectric robot includes a rotor, a stator, four connecting rods and four support members. The support member includes a limit cylinder, a spring and a support ball. The stator is wrapped around the outer surface of the rotor. The stator is made of piezoelectric ceramics. The present invention applies a specific combination of electrical signals to the stator to excite a radial bending vibration mode and two vibration modes of the stator in two orthogonal axial bending vibration modes, thereby coupling to form a slight elliptical motion on the driving surface, and driving the rotor to rotate around three axes through friction, thereby realizing translation and rotation in two directions of the piezoelectric robot. The present invention can realize translation and rotation in two directions, and has the advantages of simple and compact structure, no electromagnetic interference, self-locking when power is off, and easy miniaturization. It is suitable for fields such as robot transportation technology, target tracking technology and precision positioning platform.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric actuators, and in particular to a mobile robot based on a multi-degree-of-freedom piezoelectric actuator and an excitation method thereof. Background Art

[0002] Continuous advancements in precision drive technology are driving development in aerospace, intelligent robotics, precision instrumentation, and other fields. Actuators, as the actuators of precision instrumentation, place increasingly stringent demands and constraints on their performance. Traditional mobile robots utilize multiple single-degree-of-freedom electromagnetic motors connected in series and complex transmission mechanisms to achieve in-plane movement and rotation. This results in bulky, complex structures, and difficulty in miniaturization. Multi-degree-of-freedom piezoelectric actuators utilize the inverse piezoelectric effect of piezoelectric materials to excite the stator to produce corresponding resonant modes, thereby achieving linear or rotational motion of the rotor in multiple directions driven by friction. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a mobile robot based on a multi-degree-of-freedom piezoelectric actuator and an excitation method thereof in view of the defects involved in the background technology.

[0004] The present invention adopts the following technical solutions to solve the above technical problems:

[0005] A mobile robot based on a multi-degree-of-freedom piezoelectric actuator comprises a rotor, a stator, first to fourth connecting rods, and first to fourth supporting members;

[0006] The stator is a hollow spherical table with two ends open and symmetrical about the neutral plane between the two bottom surfaces, and includes first to eighth piezoelectric ceramic sheets;

[0007] The first to eighth piezoelectric ceramic sheets have the same structure, and are all block spherical shells. The first, third, fifth, and seventh piezoelectric ceramic sheets are connected end to end to form a spherical table on one side of the neutral plane between the two bottom surfaces of the stator. The second, fourth, sixth, and eighth piezoelectric ceramic sheets are connected end to end to form a spherical table on the other side of the neutral plane between the two bottom surfaces of the stator. The first and second piezoelectric ceramic sheets, the third and fourth piezoelectric ceramic sheets, the fifth and sixth piezoelectric ceramic sheets, and the seventh and eighth piezoelectric ceramic sheets are all symmetrical about the neutral plane between the two bottom surfaces of the stator. The first to eighth piezoelectric ceramic sheets are all polarized along the thickness direction, and the polarization directions are simultaneously facing inward or simultaneously facing outward.

[0008] The rotor is a sphere or a spherical shell, which is arranged in the stator and contacts the spherical surface of the stator, and the center of the rotor coincides with the center of the stator;

[0009] The first to fourth connecting rods have the same structure and are evenly arranged outside the stator in the circumferential direction; one end of the first to fourth connecting rods is fixedly connected to the four intersections of the pitch circle and the pitch diameter in the stator working mode, and the other end is fixedly connected to the first to fourth supporting members, so that when the mobile robot is placed on a plane, the lower ends of the first to fourth supporting members are coplanar with the lower end of the rotor to support the mobile robot to stand.

[0010] As a further optimization solution of the mobile robot based on the multi-degree-of-freedom piezoelectric actuator of the present invention, the first to fourth connecting rods are L-shaped connecting rods.

[0011] As a further optimization solution of the mobile robot based on the multi-degree-of-freedom piezoelectric actuator of the present invention, the first to fourth support members have the same structure and all include a limiting cylinder, a spring and a supporting ball;

[0012] The limiting cylinder is a hollow cylinder, and a limiting through hole for cooperating with the supporting ball is provided at the center of one end surface;

[0013] The diameter of the support ball is smaller than the diameter of the cross section of the limiting cylinder and larger than the diameter of the limiting through hole; the spring and the support ball are both arranged in the limiting cylinder; one end of the spring abuts against the closed end of the limiting cylinder, and the other end abuts against the support ball, so that a portion of the support ball is exposed from the limiting through hole;

[0014] The axes of the limiting cylinders of the first to fourth supporting members are all parallel to the axis of the stator.

[0015] The present invention also discloses a method for exciting a mobile robot based on the multi-degree-of-freedom piezoelectric actuator, comprising the following steps:

[0016] Let the center of the rotor be the Cartesian coordinate origin, the midpoint of the intersection line from the origin to the first and second piezoelectric ceramic sheets be the X-axis, the midpoint of the intersection line from the origin to the third and fourth piezoelectric ceramic sheets be the Y-axis, and the Z-axis along the axis of the rotor from the origin be the Z-axis.

[0017] If you need to move the robot along the X axis:

[0018] A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, and a third excitation signal is applied to the first, second, fifth, and sixth piezoelectric ceramic plates of the stator. The first to third excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the first excitation signal and the second excitation signal are in opposite phase, and the first excitation signal leads the third excitation signal in time phase by π / 2, so that the stator simultaneously excites a radial bending vibration mode and an axial bending vibration mode in the Y-axis direction. Through the coupling of the radial bending vibration mode and the axial bending vibration mode, a micro-elliptical motion perpendicular to the X-axis is formed on the driving surface of the stator, and the rotor is driven to rotate about the X-axis through friction, thereby enabling the mobile robot to move forward along the X-axis.

[0019] If you need to move the robot backward along the X axis, just invert the third excitation signal;

[0020] If you need to move the robot forward along the Y axis:

[0021] A fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator, and a sixth excitation signal is applied to the third, fourth, seventh, and eighth piezoelectric ceramic plates of the stator; the fourth to sixth excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the fourth excitation signal is opposite in phase to the fifth excitation signal, and the fourth excitation signal leads the sixth excitation signal in terms of time phase difference by π / 2, so that the stator simultaneously excites a radial bending vibration mode and an axial bending vibration mode in the X-axis direction; through the coupling of the radial bending vibration mode and the axial bending vibration mode, a micro-elliptical motion perpendicular to the Y-axis is formed on the driving surface of the stator, and the rotor is driven to rotate about the Y-axis through friction, thereby enabling the mobile robot to move forward along the Y-axis;

[0022] If you need to move the robot backward along the Y axis, just invert the sixth excitation signal;

[0023] If you need to move the robot to rotate along the Z axis:

[0024] A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, a fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, and a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator. The first excitation signal leads the fourth excitation signal by π / 2 in terms of time phase difference, so that the stator simultaneously excites two mutually orthogonal axial bending vibration modes. Through the coupling of the two orthogonal axial bending vibration modes, a micro-elliptical motion perpendicular to the Z axis is generated on the driving surface of the stator, and the rotor is driven to rotate about the Z axis through friction, thereby achieving positive rotation of the mobile robot along the Z axis.

[0025] If the mobile robot needs to rotate in the opposite direction along the Z axis, the first excitation signal is changed to lag behind the fourth excitation signal in terms of time phase difference by π / 2.

[0026] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0027] 1. The stator is used as the piezoelectric material to directly excite its own mode. The structure is simple and compact, avoiding the influence of errors caused by the matching between the piezoelectric material and the stator, and improving the stability of the mobile robot.

[0028] 2. The piezoelectric drive technology uses the stator to directly drive the rotor to achieve translation and rotation of the mobile robot in two directions. The spherical contact increases the driving efficiency of the mobile robot and is easy to achieve miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention;

[0030] Figure 2 Schematic diagram of the structure and polarization mode of the stator in the present invention;

[0031] Figure 3 It is a structural schematic diagram of the support member in the present invention;

[0032] Figure 4 Schematic diagram comparing the radial bending vibration modes of the stator in the positive and negative directions of the X and Y axes in the present invention;

[0033] Figure 5 Schematic diagram comparing the axial bending vibration modes of the stator in the Y-axis direction in the positive and negative directions of the Z-axis in the present invention;

[0034] Figure 6 This is a schematic diagram comparing the axial bending vibration mode of the stator in the X-axis direction and the positive and negative directions of the Z-axis in the present invention.

[0035] Figure 7 This is a schematic diagram of the stator working state when rotating around the X-axis of the present invention;

[0036] Figure 8 This is a schematic diagram of the stator working state when rotating around the Y axis of the present invention;

[0037] Figure 9 This is a schematic diagram of the stator working state when rotating around the X-axis of the present invention;

[0038] In the figure, 1-rotor, 2-stator, 3-connecting rod, 4-support, 5-limiting cylinder, 6-spring, 7-support ball. Implementation Method

[0039] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings:

[0040] The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0041] It should be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, and / or parts, these elements, components, and / or parts are not limited by these terms. These terms are merely used to distinguish elements, components, and / or parts from each other. Therefore, the first element, component, and / or part discussed below can become the second element, component, or part without departing from the teachings of the present invention.

[0042] like Figure 1 As shown, the present invention discloses a mobile robot based on a multi-degree-of-freedom piezoelectric actuator, comprising a rotor, a stator, first to fourth connecting rods, and first to fourth supporting members;

[0043] like Figure 2 As shown, the stator is a hollow spherical table with two ends open and symmetrical about the neutral plane between the two bottom surfaces, and includes first to eighth piezoelectric ceramic sheets;

[0044] The first to eighth piezoelectric ceramic sheets have the same structure, and are all block spherical shells. The first, third, fifth, and seventh piezoelectric ceramic sheets are connected end to end to form a spherical table on one side of the neutral plane between the two bottom surfaces of the stator. The second, fourth, sixth, and eighth piezoelectric ceramic sheets are connected end to end to form a spherical table on the other side of the neutral plane between the two bottom surfaces of the stator. The first and second piezoelectric ceramic sheets, the third and fourth piezoelectric ceramic sheets, the fifth and sixth piezoelectric ceramic sheets, and the seventh and eighth piezoelectric ceramic sheets are all symmetrical about the neutral plane between the two bottom surfaces of the stator. The first to eighth piezoelectric ceramic sheets are all polarized along the thickness direction, and the polarization directions are simultaneously facing inward or simultaneously facing outward.

[0045] The rotor is a sphere or a spherical shell, which is arranged in the stator and contacts the spherical surface of the stator, and the center of the rotor coincides with the center of the stator;

[0046] The first to fourth connecting rods have the same structure and are evenly arranged outside the stator in the circumferential direction; one end of the first to fourth connecting rods is fixedly connected to the four intersections of the pitch circle and the pitch diameter in the stator working mode, and the other end is fixedly connected to the first to fourth supporting members, so that when the mobile robot is placed on a plane, the lower ends of the first to fourth supporting members are coplanar with the lower end of the rotor to support the mobile robot to stand.

[0047] The first to fourth connecting rods are preferably L-shaped connecting rods.

[0048] like Figure 3 As shown, the first to fourth supporting members have the same structure, and all include a limiting cylinder, a spring and a supporting ball;

[0049] The limiting cylinder is a hollow cylinder, and a limiting through hole for cooperating with the supporting ball is provided at the center of one end surface;

[0050] The diameter of the support ball is smaller than the diameter of the cross section of the limiting cylinder and larger than the diameter of the limiting through hole; the spring and the support ball are both arranged in the limiting cylinder; one end of the spring abuts against the closed end of the limiting cylinder, and the other end abuts against the support ball, so that a portion of the support ball is exposed from the limiting through hole;

[0051] The axes of the limiting cylinders of the first to fourth supporting members are all parallel to the axis of the stator.

[0052] The present invention also discloses a method for exciting a mobile robot based on a multi-degree-of-freedom piezoelectric actuator, comprising the following steps:

[0053] like Figure 2 As shown, let the center of the rotor be the Cartesian coordinate origin, the midpoint of the intersection line from the coordinate origin to the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet be the X-axis, the midpoint of the intersection line from the coordinate origin to the third piezoelectric ceramic sheet and the fourth piezoelectric ceramic sheet be the Y-axis, and the Z-axis is from the coordinate origin along the axis of the rotor;

[0054] If you need to move the robot along the X axis:

[0055] A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, and a third excitation signal is applied to the first, second, fifth, and sixth piezoelectric ceramic plates of the stator; the first to third excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the first excitation signal and the second excitation signal have opposite phases, and the first excitation signal leads the third excitation signal by π / 2 in terms of time phase difference, so that the stator simultaneously excites the radial bending vibration mode and the axial bending vibration mode in the Y-axis direction, such as Figure 4 and Figure 5 As shown; through the coupling of radial bending vibration mode and axial bending vibration mode, a micro-elliptical motion perpendicular to the X-axis is formed on the driving surface of the stator, and the rotor is driven to rotate around the X-axis through friction, as shown Figure 7 As shown, the mobile robot moves forward along the X axis;

[0056] If you need to move the robot backward along the X axis, just invert the third excitation signal;

[0057] If you need to move the robot forward along the Y axis:

[0058] A fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator, and a sixth excitation signal is applied to the third, fourth, seventh, and eighth piezoelectric ceramic plates of the stator; the fourth to sixth excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the fourth excitation signal is opposite in phase to the fifth excitation signal, and the fourth excitation signal leads the sixth excitation signal in time phase difference by π / 2, so that the stator simultaneously excites the radial bending vibration mode and the axial bending vibration mode in the X-axis direction, as shown in FIG. Figure 4 and Figure 6 As shown; through the coupling of radial bending vibration mode and axial bending vibration mode, a micro-elliptical motion perpendicular to the Y axis is formed on the driving surface of the stator, and the rotor is driven to rotate around the Y axis through friction, as shown Figure 8 As shown, the mobile robot moves forward along the Y axis;

[0059] If you need to move the robot backward along the Y axis, just invert the sixth excitation signal;

[0060] If you need to move the robot to rotate along the Z axis:

[0061] A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, a fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, and a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator; wherein the first excitation signal leads the fourth excitation signal by π / 2 in time phase difference, so that the stator simultaneously excites two mutually orthogonal axial bending vibration modes, such as Figure 5 and Figure 6 As shown; through the coupling of two orthogonal axial bending vibration modes, a micro-elliptical motion perpendicular to the Z axis is formed on the driving surface of the stator, and the rotor is driven to rotate around the Z axis through friction, as shown Figure 9 As shown, the mobile robot can rotate in the positive direction along the Z axis;

[0062] If the mobile robot needs to rotate in the opposite direction along the Z axis, the first excitation signal is changed to lag behind the fourth excitation signal in terms of time phase difference by π / 2.

[0063] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, will not be interpreted in an idealized or overly formal sense.

[0064] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A mobile robot based on a multi-degree-of-freedom piezoelectric actuator, characterized in that: The invention comprises a rotor, a stator, first to fourth connecting rods, and first to fourth supporting members; The stator is a hollow spherical table with two ends open and symmetrical about the neutral plane between the two bottom surfaces, and includes first to eighth piezoelectric ceramic sheets; The first to eighth piezoelectric ceramic sheets have the same structure, and are all block spherical shells. The first, third, fifth, and seventh piezoelectric ceramic sheets are connected end to end to form a spherical table on one side of the neutral plane between the two bottom surfaces of the stator. The second, fourth, sixth, and eighth piezoelectric ceramic sheets are connected end to end to form a spherical table on the other side of the neutral plane between the two bottom surfaces of the stator. The first and second piezoelectric ceramic sheets, the third and fourth piezoelectric ceramic sheets, the fifth and sixth piezoelectric ceramic sheets, and the seventh and eighth piezoelectric ceramic sheets are all symmetrical about the neutral plane between the two bottom surfaces of the stator. The first to eighth piezoelectric ceramic sheets are all polarized along the thickness direction, and the polarization directions are simultaneously facing inward or simultaneously facing outward. The rotor is a sphere or a spherical shell, which is arranged in the stator and contacts the spherical surface of the stator, and the center of the rotor coincides with the center of the stator; The first to fourth connecting rods have the same structure and are evenly arranged outside the stator in the circumferential direction; one end of the first to fourth connecting rods is fixedly connected to the four intersections of the pitch circle and the pitch diameter in the stator working mode, and the other end is fixedly connected to the first to fourth supporting members, so that when the mobile robot is placed on a plane, the lower ends of the first to fourth supporting members are coplanar with the lower end of the rotor to support the mobile robot to stand.

2. The mobile robot based on a multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The first to fourth connecting rods are L-shaped connecting rods.

3. The mobile robot based on a multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The first to fourth support members have the same structure and all include a limiting cylinder, a spring and a support ball; The limiting cylinder is a hollow cylinder, and a limiting through hole for cooperating with the supporting ball is provided at the center of one end surface; The diameter of the support ball is smaller than the diameter of the cross section of the limiting cylinder and larger than the diameter of the limiting through hole; the spring and the support ball are both arranged in the limiting cylinder; one end of the spring abuts against the closed end of the limiting cylinder, and the other end abuts against the support ball, so that a portion of the support ball is exposed from the limiting through hole; The axes of the limiting cylinders of the first to fourth supporting members are all parallel to the axis of the stator.

4. The method for exciting a mobile robot based on a multi-degree-of-freedom piezoelectric actuator according to claim 1, characterized in that: The following steps are involved: Let the center of the rotor be the Cartesian coordinate origin, the midpoint of the intersection line from the origin to the first and second piezoelectric ceramic sheets be the X-axis, the midpoint of the intersection line from the origin to the third and fourth piezoelectric ceramic sheets be the Y-axis, and the Z-axis along the axis of the rotor from the origin be the Z-axis. If you need to move the robot along the X axis: A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, and a third excitation signal is applied to the first, second, fifth, and sixth piezoelectric ceramic plates of the stator. The first to third excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the first excitation signal and the second excitation signal are in opposite phase, and the first excitation signal leads the third excitation signal in time phase by π / 2, so that the stator simultaneously excites a radial bending vibration mode and an axial bending vibration mode in the Y-axis direction. Through the coupling of the radial bending vibration mode and the axial bending vibration mode, a micro-elliptical motion perpendicular to the X-axis is formed on the driving surface of the stator, and the rotor is driven to rotate about the X-axis through friction, thereby enabling the mobile robot to move forward along the X-axis. If you need to move the robot backward along the X axis, just invert the third excitation signal; If you need to move the robot forward along the Y axis: A fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator, and a sixth excitation signal is applied to the third, fourth, seventh, and eighth piezoelectric ceramic plates of the stator; the fourth to sixth excitation signals are all AC harmonic signals of the same frequency and amplitude, wherein the fourth excitation signal is opposite in phase to the fifth excitation signal, and the fourth excitation signal leads the sixth excitation signal in terms of time phase difference by π / 2, so that the stator simultaneously excites a radial bending vibration mode and an axial bending vibration mode in the X-axis direction; through the coupling of the radial bending vibration mode and the axial bending vibration mode, a micro-elliptical motion perpendicular to the Y-axis is formed on the driving surface of the stator, and the rotor is driven to rotate about the Y-axis through friction, thereby enabling the mobile robot to move forward along the Y-axis; If you need to move the robot backward along the Y axis, just invert the sixth excitation signal; If you need to move the robot to rotate along the Z axis: A first excitation signal is applied to the third and eighth piezoelectric ceramic plates of the stator, a second excitation signal is applied to the fourth and seventh piezoelectric ceramic plates of the stator, a fourth excitation signal is applied to the first and sixth piezoelectric ceramic plates of the stator, and a fifth excitation signal is applied to the second and fifth piezoelectric ceramic plates of the stator. The first excitation signal leads the fourth excitation signal by π / 2 in terms of time phase difference, so that the stator simultaneously excites two mutually orthogonal axial bending vibration modes. Through the coupling of the two orthogonal axial bending vibration modes, a micro-elliptical motion perpendicular to the Z axis is generated on the driving surface of the stator, and the rotor is driven to rotate about the Z axis through friction, thereby achieving positive rotation of the mobile robot along the Z axis. If the mobile robot needs to rotate in the opposite direction along the Z axis, the first excitation signal is changed to lag behind the fourth excitation signal in terms of time phase difference by π / 2.

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