Three-degree-of-freedom spherical motor based on array piezoelectric unit and driving method

Abstract

The application discloses a three-degree-of-freedom spherical motor based on an array piezoelectric unit and a driving method, the spherical motor comprising a shell, a mover, driving units and a control unit, wherein the mover is assembled in the inner cavity of the shell, the driving units are provided with a plurality of driving units, the plurality of driving units are embedded on the shell wall of the shell, the plurality of driving units are in abutment with the mover, the plurality of driving units can drive the mover to move at any angle, the mover is connected with the control unit through a data transmission unit, and the driving method comprises the following steps: step one, setting a motion coordinate system according to the horizontal and vertical distribution array of the driving units; step two, rotating the spherical motor around the X axis; step three, dividing into two driving schemes; step four, precise positioning mode; step five, fast driving mode; step six, changing the controlled unit into an X axis driving unit array; and step seven, rotating the spherical motor around the Z axis. The spherical motor has the advantages of small volume, light weight, high positioning precision and good dynamic performance.

Description

Technical Field

[0001] This invention relates to a three-degree-of-freedom spherical motor and its driving method, and particularly to a three-degree-of-freedom spherical motor and its driving method based on an array of piezoelectric units. Background Technology

[0002] Currently, the spherical motor is a new type of drive device that can achieve multi-degree-of-freedom rotational motion through a single rotor. Compared with the method of increasing the degree of freedom by connecting multiple motors in series, it can significantly reduce the structural size and complexity, reduce system power consumption and control difficulty, and has the advantages of small size, compact structure and flexible movement.

[0003] Currently, research on spherical motors is mostly based on traditional electromagnetic motors. This involves embedding electromagnetic wires in a spherical array within a spherical stator to create a multi-degree-of-freedom rotatable magnetic field, which drives the rotor to rotate. For example, patent CN202110137434.6 describes electromagnets arranged along the longitude and latitude directions on the inner surface of the stator spherical shell, with each electromagnet pointing towards the center of the stator shell. Additionally, an array of iron blocks is installed on the outer surface of the spherical rotor. However, this method requires a large number of electromagnets and iron cores, which is detrimental to the miniaturization of spherical motors. Furthermore, the inconvenience of installing a reduction gear mechanism in spherical motors limits the driving force and positioning accuracy of the electromagnetic drive, severely restricting the application value of spherical motors in fields such as precision robots and precision instruments.

[0004] To address the aforementioned issues, this invention proposes a three-degree-of-freedom spherical motor based on an array of piezoelectric units. The piezoelectric elements provide high precision and high output force, while the torque direction is controlled by an array of drive units to achieve three-degree-of-freedom driving functionality. The collaborative driving of the array of drive units regulates the driving friction force, improving friction transmission efficiency to achieve high-speed motion. Furthermore, the synchronous action of the array of drive units provides precise positioning and high torque output. Summary of the Invention

[0005] The main purpose of this invention is to solve the problem that existing spherical motors are inconvenient to install reduction mechanisms, which limits the driving force and positioning accuracy of electromagnetic drives. This severely restricts the application of spherical motors in fields such as precision robots and precision instruments. The invention provides a three-degree-of-freedom spherical motor based on an array of piezoelectric units and a driving method.

[0006] The three-degree-of-freedom spherical motor based on arrayed piezoelectric units provided by this invention includes a housing, a mover, a drive unit, and a control unit. The mover is assembled in the inner cavity of the housing. Several drive units are provided and embedded in the shell wall of the housing, and each drive unit abuts against the mover. The drive units can drive the mover to move at any angle. The mover is connected to the control unit through a data transmission unit. The data transmission unit can transmit the collected motion data of the mover to the control unit in real time. The control unit is also connected to several drive units. The control unit drives the mover to move at a set angle according to the data transmission instructions from the data transmission unit.

[0007] The outer shell has a hemispherical structure. The top of the outer shell is equipped with a limit end cap. Several limit holes are opened around the perimeter of the limit end cap. A ball-head plunger is inserted into each limit hole. The ball head end of the ball-head plunger abuts against the mover. The ball-head plunger is used to limit the mover. The perimeter of the outer shell wall is provided with mounting holes corresponding to the number of drive units. The drive units are assembled in the mounting holes.

[0008] The mover is a spherical hollow structure, and the hollow part is used to assemble the data transmission unit. The data transmission unit between the mover and the control unit is a displacement sensor, and the displacement sensor and the control unit are connected by wireless communication.

[0009] Several drive units are assembled in pairs around the perimeter of the housing. Each drive unit consists of a piezoelectric bending deformation element, a piezoelectric shear deformation element, and a drive foot. The piezoelectric bending deformation element is located at the bottom. The piezoelectric shear deformation element and the drive foot are connected sequentially to the top surface of the piezoelectric bending deformation element. The piezoelectric bending deformation element, the piezoelectric shear deformation element, and the drive foot are bonded together. A circular protrusion is mounted on the top surface of the drive foot opposite to the mover. The top of the circular protrusion abuts against the mover. The output displacement of the piezoelectric bending deformation element and the piezoelectric shear deformation element is transmitted to the mover through the drive foot, thereby driving the mover to move at a set angle. A pre-tightening screw cap is mounted at the contact point between the bottom of the piezoelectric bending deformation element and the shell wall of the housing. The pre-tightening screw cap is screwed to the shell wall of the housing and is used to clamp and fix the drive unit.

[0010] The control unit is a host computer, which can output the control signals required by the drive unit. The output signal of the host computer is a sawtooth wave, square wave, or sine wave. A power amplifier is installed on the connection line between the host computer and each drive unit. The control signal output by the host computer is applied to the piezoelectric bending deformation element and piezoelectric shear deformation element in the drive unit after being amplified by the power amplifier, and generates a set displacement. This causes the piezoelectric bending deformation element and piezoelectric shear deformation element to drive the mover to rotate at a set angle. The displacement of the mover during rotation is measured by the displacement sensor inside the mover. The displacement measurement method is machine vision positioning or gyroscope feedback. The displacement sensor transmits the measured displacement data of the mover to the host computer in real time.

[0011] The displacement sensor, piezoelectric bending deformation element, piezoelectric shear deformation element, drive foot, host computer and power amplifier mentioned above are all assemblies of existing equipment, therefore, the specific models and specifications are not described in detail.

[0012] The present invention provides a driving method for a three-degree-of-freedom spherical motor based on an array of piezoelectric units, the method comprising the following steps:

[0013] Step 1: Set the motion coordinate system O-XYZ according to the horizontal and vertical distribution array of the drive unit, where O is the center of the mover ball, one column of the drive unit coincides with the X-axis, the other column coincides with the Y-axis, and the Z-axis is perpendicular to the X-axis and Y-axis, pointing upwards from the motor.

[0014] Step 2: When the spherical motor rotates around the X-axis, the control unit instructs the piezoelectric bending deformation elements in each drive unit on the X-axis to deform away from the mover, thereby reducing the frictional resistance of the X-axis drive unit array to the mover.

[0015] Step 3: Based on different driving purposes, there are two driving schemes: precise positioning and fast driving.

[0016] Step 4: In precise positioning mode, the control unit directly controls the Y-axis shear deformation of each piezoelectric shear deformation element in the Y-axis drive unit array, and generates precise angular displacement by driving the mover through the drive foot.

[0017] Step 5: In the fast drive mode, the control unit instructs each drive unit on the Y-axis to work together. The motion trajectories of each drive unit are consistent but different in phase. The motion trajectory of each drive unit is as follows: First, the piezoelectric bending deformation element deforms towards the mover, increasing the contact force between the Y-axis drive unit and the mover, thus improving the driving capability. Then, the control unit instructs the piezoelectric shear deformation element to generate displacement along the Y-axis, driving the mover to rotate. After that, the piezoelectric bending deformation element deforms away from the mover, reducing the contact force between the Y-axis drive unit and the mover, and weakening the reverse driving effect on the mover when the piezoelectric shear deformation element resets. Finally, the control unit instructs the piezoelectric shear deformation element to reset. If the number of Y-axis drive units is m, then the phase difference of each drive unit is set to 2π / m and increases sequentially. Each drive unit works in a coordinated manner to achieve traveling wave drive, thus enhancing the driving capability.

[0018] Step 6: The rotational motion of the spherical motor around the Y-axis is basically the same as the motion of the spherical motor around the X-axis. The difference is that the control unit commands the piezoelectric bending deformation elements in each drive unit on the Y-axis to deform away from the mover, thereby reducing the frictional resistance of the Y-axis drive unit array to the mover. At the same time, the controlled unit is changed to the X-axis drive unit array.

[0019] Step 7: When the spherical motor rotates around the Z-axis, the control method is adjusted as follows: the X-axis and Y-axis drive units move together, the piezoelectric shear deformation element in the X-axis drive unit array generates Y-axis deformation, and the piezoelectric shear deformation element in the Y-axis drive unit array generates X-axis deformation.

[0020] The assembly structure principle of this invention:

[0021] The mover in the three-degree-of-freedom spherical motor based on arrayed piezoelectric units provided by this invention is assembled in the inner cavity of the outer shell, but does not contact the inner shell wall. The mover contacts the circular protrusions on the top of several driving feet and is driven by the array of driving feet. As the output part of the spherical motor for displacement and force, the mover is designed as a hollow structure to assemble displacement sensors and other devices, or to add connecting threads to connect with the driving load.

[0022] The limiting end cap is assembled on the top of the housing and is connected by a threaded connection. The limiting end cap serves to fix the mover in the inner cavity of the housing. Limiting holes are provided around the periphery of the limiting end cap for the assembly of the ball plunger.

[0023] The outer shell, as the main body of the spherical motor, serves to accommodate the various components and enable them to work in coordination. Several mounting holes are provided on the shell wall for assembling the drive foot, piezoelectric shear deformation element and piezoelectric bending deformation element in the drive unit. The shell wall is also provided with threaded holes that match the limit end cap and pre-tightening screw cap.

[0024] The preload screw cap is assembled on the outside of the mounting hole in the outer shell wall. The connection between the preload screw cap and the mounting hole is by screwing. The preload screw cap is used to press the drive unit, which consists of the drive foot, the piezoelectric shear deformation element and the piezoelectric bending deformation element, into the shell wall of the outer shell.

[0025] The driving foot is connected to the piezoelectric shear deformation element and the piezoelectric bending deformation element to form a driving unit. The connection method is adhesive bonding. The driving foot is in direct contact with the mover, which serves to position the mover and drive it. The piezoelectric shear deformation element is connected to the driving foot and the piezoelectric bending deformation element by adhesive bonding. The piezoelectric shear deformation element can generate shear deformation with two degrees of freedom to generate displacement of the moving part. The piezoelectric bending deformation element can generate a large linear displacement to control the change of contact force between the driving unit and the mover. The driving unit is assembled in the mounting holes on the outer shell wall. The driving unit is distributed horizontally, vertically and horizontally along the inner surface of the outer shell and is pressed by pre-tightening screw caps.

[0026] The ball plunger is assembled in the limiting end cap. The ball head of the ball plunger is in direct contact with the mover. Together with the limiting end cap, it serves to constrain the mover in the inner cavity of the housing. The ball plunger provides preload between the mover and the drive foot.

[0027] The beneficial effects of this invention are:

[0028] The three-degree-of-freedom spherical motor and driving method based on arrayed piezoelectric units provided by this invention can generate torque in different directions through arrayed piezoelectric drive units, realizing three-degree-of-freedom driving of a single spherical mover. The drive device has a compact structure and is easy to miniaturize. Through the coordinated action of the arrayed drive units, this invention can increase the contact force and driving effect of the working drive unit on the spherical mover, and reduce the contact force and resistance of the idle drive unit. At the same time, by coordinating the phase relationship of the drive unit array, it can significantly improve the friction transmission efficiency to achieve high-speed rotor movement. Through the synchronous action of the arrayed drive units, this invention achieves high-precision and high-load driving capability for the spherical motor mover.

[0029] This invention boasts numerous advantages, including small size, light weight, high positioning accuracy, and excellent dynamic performance. It has wide applications in robot joints, precision gimbals, and multi-degree-of-freedom motion systems, demonstrating high practical value and strong usability. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the spherical motor described in this invention.

[0031] Figure 2 This is a schematic diagram of the outer shell structure described in this invention.

[0032] Figure 3This is a schematic diagram of the cross-sectional structure of the outer shell described in this invention.

[0033] Figure 4 This is a schematic diagram of the connection relationship between the mover and the driving unit described in this invention.

[0034] Figure 5 This is a schematic diagram of the drive unit structure described in this invention.

[0035] Figure 6 This is a top view of the limiting end cap described in this invention.

[0036] Figure 7 This is a schematic diagram of the connection structure between the ball-head plunger and the moving part according to the present invention.

[0037] Figure 8 This is a block diagram showing the connection relationship between the control unit, drive unit, and mover described in this invention.

[0038] Figure 9 This is a schematic diagram of the driving method described in this invention.

[0039] The annotations in the above-mentioned figures are as follows:

[0040] 1. Outer casing 2. Moving element 3. Drive unit 4. Control unit 5. Data transmission unit

[0041] 6. Limiting end cap; 7. Limiting hole; 8. Ball plunger; 9. Mounting hole; 10. Piezoelectric bending deformation element.

[0042] 11. Piezoelectric shear deformation element; 12. Drive foot; 13. Circular protrusion; 14. Preload screw cap.

[0043] 15. Power amplifier. Detailed Implementation

[0044] Please see Figures 1 to 9 As shown:

[0045] The three-degree-of-freedom spherical motor based on arrayed piezoelectric units provided by the present invention includes a housing 1, a mover 2, a drive unit 3, and a control unit 4. The mover 2 is assembled in the inner cavity of the housing 1. Several drive units 3 are provided and embedded in the shell wall of the housing 1. The drive units 3 all abut against the mover 2 and can drive the mover 2 to move at any angle. The mover 2 is connected to the control unit 4 through a data transmission unit 5. The data transmission unit 5 can transmit the collected motion data of the mover 2 to the control unit 4 in real time. The control unit 4 is also connected to several drive units 3 respectively. The control unit 4 drives the mover 2 to move at a set angle according to the data transmission instructions of the data transmission unit 5.

[0046] The outer shell 1 has a hemispherical structure. The top of the outer shell 1 is equipped with a limiting end cap 6. Several limiting holes 7 are opened around the periphery of the limiting end cap 6. A ball-head plunger 8 is inserted into each limiting hole 7. The ball head end of the ball-head plunger 8 abuts against the mover 2. The ball-head plunger 8 is used to limit the mover 2. The periphery of the outer shell 1 is provided with mounting holes 9 corresponding to the number of drive units 3. The drive units 3 are assembled in the mounting holes 9.

[0047] The mover 2 is a spherical hollow structure. The hollow part is used to assemble the data transmission unit 5. The data transmission unit 5 between the mover 2 and the control unit 4 is a displacement sensor. The displacement sensor and the control unit 4 are connected by wireless communication.

[0048] Several drive units 3 are assembled in pairs around the perimeter of the outer casing 1. Each drive unit 3 consists of a piezoelectric bending deformation element 10, a piezoelectric shear deformation element 11, and a drive foot 12. The piezoelectric bending deformation element 10 is located at the bottom. The piezoelectric shear deformation element 11 and the drive foot 12 are sequentially connected to the top surface of the piezoelectric bending deformation element 10. The piezoelectric bending deformation element 10, the piezoelectric shear deformation element 11, and the drive foot 12 are bonded together. A circular protrusion 13 is mounted on the top surface of the drive foot 12 opposite to the mover 2. The top of the circular protrusion 13 abuts against the mover 2. The output displacement of the piezoelectric bending deformation element 10 and the piezoelectric shear deformation element 11 is transmitted to the mover 2 through the drive foot 12, thereby driving the mover 2 to move at a set angle. A pre-tightening screw cap 14 is mounted at the contact part between the bottom of the piezoelectric bending deformation element 10 and the shell wall of the outer casing 1. The pre-tightening screw cap 14 is screwed to the shell wall of the outer casing 1 and is used to press and fix the drive unit 3.

[0049] The control unit 4 is a host computer that can output the control signals required by the drive unit 3. The output signal of the host computer is a sawtooth wave, square wave or sine wave. A power amplifier 15 is installed on the connection line between the host computer and each drive unit 3. The control signal output by the host computer is applied to the piezoelectric bending deformation element 10 and piezoelectric shear deformation element 11 in the drive unit 3 after passing through the power amplifier 15 and generates a set displacement. This causes the piezoelectric bending deformation element 10 and piezoelectric shear deformation element 11 to drive the mover 2 to rotate at a set angle. The displacement of the mover 2 during rotation is measured by the displacement sensor inside the mover 2. The displacement measurement method is machine vision positioning or gyroscope feedback. The displacement sensor transmits the measured displacement data of the mover 2 to the host computer in real time.

[0050] The displacement sensor, piezoelectric bending deformation element 10, piezoelectric shear deformation element 11, drive foot 12, host computer and power amplifier 15 mentioned above are all assemblies of existing equipment, therefore, the specific models and specifications are not described in detail.

[0051] The present invention provides a driving method for a three-degree-of-freedom spherical motor based on an array of piezoelectric units, the method comprising the following steps:

[0052] Step 1: Set the motion coordinate system O-XYZ according to the horizontal and vertical distribution array of the drive unit 3, where O is the center of the sphere of the mover 2, one column of the drive unit 3 coincides with the X-axis, the other column coincides with the Y-axis, and the Z-axis is perpendicular to the X-axis and Y-axis and points upwards from the motor.

[0053] Step 2: When the spherical motor rotates around the X-axis, the control unit 4 instructs the piezoelectric bending deformation element 10 in each drive unit 3 on the X-axis to deform away from the mover 2, thereby reducing the frictional resistance of the X-axis drive unit 3 array to the mover 2.

[0054] Step 3: Based on different driving purposes, there are two driving schemes: precise positioning and fast driving.

[0055] Step 4: In the precise positioning mode, the control unit 4 directly controls the Y-axis shear deformation of each piezoelectric shear deformation element 11 in the Y-axis drive unit 3 array, and drives the mover 2 to generate precise angular displacement through the drive foot 12.

[0056] Step 5: In the fast drive mode, the control unit 4 instructs each drive unit 3 on the Y-axis to work together. The motion trajectories of each drive unit 3 are consistent but the phases are different. The motion trajectories of each drive unit 3 are as follows: First, the piezoelectric bending deformation element 10 deforms towards the mover 2, increasing the contact force between the Y-axis drive unit 3 and the mover 2, thus improving the driving capability. Then, the control unit 4 instructs the piezoelectric shear deformation element 11 to generate displacement along the Y-axis direction, driving the mover 2 to rotate. After that, the piezoelectric bending deformation element 10 deforms away from the mover 2, reducing the contact force between the Y-axis drive unit 3 and the mover 2, weakening the reverse driving effect on the mover 2 when the piezoelectric shear deformation element 11 resets. Finally, the control unit 4 instructs the piezoelectric shear deformation element 11 to reset. If the number of Y-axis drive units 3 is m, then the phase difference of each drive unit 3 is set to 2π / m and increases sequentially. Each drive unit 12 works together to achieve a traveling wave drive, thus enhancing the driving capability.

[0057] Step 6: The rotational motion of the spherical motor around the Y-axis is basically the same as the motion of the spherical motor around the X-axis. The difference is that the control unit 4 instructs the piezoelectric bending deformation element 10 in each drive unit 3 on the Y-axis to deform away from the mover 2, thereby reducing the frictional resistance of the Y-axis drive unit 3 array to the mover 2. At the same time, the controlled unit is changed to the X-axis drive unit 3 array.

[0058] Step 7: When the spherical motor rotates around the Z-axis, the control mode is adjusted as follows: the X-axis and Y-axis drive units 3 operate together, the piezoelectric shear deformation element 11 in the X-axis drive unit 3 array generates Y-axis deformation, and the piezoelectric shear deformation element 11 in the Y-axis drive unit 3 array generates X-axis deformation.

[0059] The assembly structure principle of this invention:

[0060] The mover 2 in the three-degree-of-freedom spherical motor based on arrayed piezoelectric units provided by the present invention is assembled in the inner cavity of the outer shell 1, but does not contact the inner shell wall of the outer shell 1. The mover 2 contacts the circular protrusions 13 on the top of several driving feet 12 and is driven by the array of driving feet 12. As the output part of the spherical motor for displacement and force, the mover 2 is designed as a hollow structure to assemble displacement sensors and other devices, or to add connecting threads to connect with the driving load.

[0061] The limiting end cap 6 is assembled on the top of the outer shell 1 and the connection method is threaded connection. The limiting end cap 6 serves to fix the moving part 2 in the inner cavity of the outer shell 1. The limiting end cap 6 has a limiting hole 7 around its periphery for the assembly of the ball head plunger 8.

[0062] The outer shell 1 serves as the main body of the spherical motor, accommodating the various components and enabling them to work in coordination. Several mounting holes 9 are provided on the shell wall of the outer shell 1 for assembling the drive foot 12, piezoelectric shear deformation element 11, and piezoelectric bending deformation element 10 in the drive unit 3. The shell wall of the outer shell 1 is also provided with threaded holes that match the limiting end cap 6 and the pre-tightening screw cap 14.

[0063] The pre-tightening screw cap 14 is assembled on the outside of the mounting hole 9 on the shell wall of the outer casing 1. The connection between the pre-tightening screw cap 14 and the mounting hole 9 is by screwing. The pre-tightening screw cap 14 is used to press the drive unit 3, which consists of the drive foot 12, the piezoelectric shear deformation element 11 and the piezoelectric bending deformation element 10, into the shell wall of the outer casing 1.

[0064] The driving foot 12 is connected to the piezoelectric shear deformation element 11 and the piezoelectric bending deformation element 10 to form the driving unit 3. The connection method is adhesive bonding. The driving foot 12 is in direct contact with the mover 2, which serves to position the mover 2 on the one hand and drive the mover 2 on the other. The piezoelectric shear deformation element 11 is connected to the driving foot 12 and the piezoelectric bending deformation element 10 by adhesive bonding. The piezoelectric shear deformation element 11 can generate shear deformation with two degrees of freedom, which is used to generate displacement of the mover 2. The piezoelectric bending deformation element 10 can generate a large linear displacement, which is used to control the change of contact force between the driving unit 3 and the mover 2. The driving unit 3 is assembled in the mounting hole 9 on the shell wall of the outer shell 1. The driving unit 3 is distributed horizontally, vertically and horizontally along the inner surface of the outer shell 1 and is pressed by the pre-tightening screw cap 14.

[0065] The ball plunger 8 is assembled in the limiting end cover 6. The ball end of the ball plunger 8 is in direct contact with the mover 2. Together with the limiting end cover 6, it serves to constrain the mover 2 in the inner cavity of the outer shell 1. The ball plunger 8 provides preload force between the mover 2 and the drive foot 12.

Claims

1. A three-degree-of-freedom spherical motor based on an array of piezoelectric units, comprising a housing, a mover, drive units, and a control unit, wherein the mover is assembled in the inner cavity of the housing, several drive units are provided and embedded in the housing wall, each drive unit abutting against the mover, and the drive units can drive the mover to move at any angle, the mover is connected to the control unit through a data transmission unit, the data transmission unit can transmit the collected mover motion data to the control unit in real time, the control unit is also connected to several drive units respectively, and the control unit drives the mover to move at a set angle according to the data transmitted by the data transmission unit, characterized in that: Several drive units are assembled in pairs around the perimeter of the outer shell. Each drive unit consists of a piezoelectric bending deformation element, a piezoelectric shear deformation element, and a drive foot. The piezoelectric bending deformation element is located at the bottom. The piezoelectric shear deformation element and the drive foot are sequentially connected to the top surface of the piezoelectric bending deformation element. The piezoelectric bending deformation element, the piezoelectric shear deformation element, and the drive foot are bonded together. A circular protrusion is mounted on the top surface of the drive foot opposite to the mover. The top of the circular protrusion abuts against the mover. The output displacement of the piezoelectric bending deformation element and the piezoelectric shear deformation element is transmitted to the mover through the drive foot, thereby driving the mover to move at a set angle. A pre-tightening screw cap is mounted at the contact point between the bottom of the piezoelectric bending deformation element and the shell wall of the outer shell. The pre-tightening screw cap is screwed to the shell wall of the outer shell and is used to press and fix the drive unit.

2. A three-degree-of-freedom spherical motor based on an array of piezoelectric units according to claim 1, characterized in that: The outer shell is a hemispherical structure. The top of the outer shell is fitted with a limiting end cap. Several limiting holes are opened around the perimeter of the limiting end cap. A ball-head plunger is inserted into each limiting hole. The ball head end of the ball-head plunger abuts against the mover. The ball-head plunger is used to limit the mover. The perimeter of the outer shell wall is provided with mounting holes corresponding to the number of drive units. The drive units are assembled in the mounting holes.

3. A three-degree-of-freedom spherical motor based on an array of piezoelectric units according to claim 1, characterized in that: The mover is a spherical hollow structure, and the hollow part is used to assemble the data transmission unit. The data transmission unit between the mover and the control unit is a displacement sensor, and the displacement sensor and the control unit are connected by wireless communication.

4. A three-degree-of-freedom spherical motor based on an array of piezoelectric units according to claim 1, characterized in that: The control unit is a host computer, which can output the control signals required by the drive unit. The output signal of the host computer is a sawtooth wave, square wave, or sine wave. A power amplifier is installed on the connection line between the host computer and each drive unit. The control signal output by the host computer is applied to the piezoelectric bending deformation element and the piezoelectric shear deformation element in the drive unit after being amplified by the power amplifier, and causes them to generate a set displacement. This causes the piezoelectric bending deformation element and the piezoelectric shear deformation element to drive the mover to rotate at a set angle. The displacement of the mover during rotation is measured by the displacement sensor inside the mover. The displacement measurement method is machine vision positioning or gyroscope feedback. The displacement sensor transmits the measured displacement data of the mover to the host computer in real time.

5. A driving method for a three-degree-of-freedom spherical motor based on an array of piezoelectric units, characterized in that: The method includes the following steps: Step 1: Set the motion coordinate system O-XYZ according to the horizontal and vertical distribution array of the drive unit, where O is the center of the mover ball, one column of the drive unit coincides with the X-axis, the other column coincides with the Y-axis, and the Z-axis is perpendicular to the X-axis and Y-axis, pointing upwards from the motor. Step 2: When the spherical motor rotates around the X-axis, the control unit instructs the piezoelectric bending deformation elements in each drive unit on the X-axis to deform away from the mover, thereby reducing the frictional resistance of the X-axis drive unit array to the mover. Step 3: Based on different driving purposes, there are two driving schemes: precise positioning and fast driving. Step 4: In precise positioning mode, the control unit directly controls the Y-axis shear deformation of each piezoelectric shear deformation element in the Y-axis drive unit array, and generates precise angular displacement by driving the actuator through the drive foot. Step 5: In the fast drive mode, the control unit instructs each drive unit on the Y-axis to work together. The motion trajectories of each drive unit are consistent but different in phase. The motion trajectory of each drive unit is as follows: First, the piezoelectric bending deformation element deforms towards the mover, increasing the contact force between the Y-axis drive unit and the mover, thus improving the driving capability. Then, the control unit instructs the piezoelectric shear deformation element to generate displacement along the Y-axis, driving the mover to rotate. After that, the piezoelectric bending deformation element deforms away from the mover, reducing the contact force between the Y-axis drive unit and the mover, and weakening the reverse driving effect on the mover when the piezoelectric shear deformation element resets. Finally, the control unit instructs the piezoelectric shear deformation element to reset. If the number of Y-axis drive units is m, then the phase difference of each drive unit is set to 2π / m and increases sequentially. Each drive unit works in a coordinated manner to achieve traveling wave drive, thus enhancing the driving capability. Step 6: The spherical motor rotates around the Y-axis in the same way as the spherical motor rotates around the X-axis. The difference is that the control unit commands the piezoelectric bending deformation elements in each drive unit on the Y-axis to deform away from the mover, thereby reducing the frictional resistance of the Y-axis drive unit array to the mover. At the same time, the controlled drive unit is changed to the X-axis drive unit array. Step 7: When the spherical motor rotates around the Z-axis, the control method is adjusted as follows: the X-axis and Y-axis drive units move together, the piezoelectric shear deformation element in the X-axis drive unit array generates Y-axis deformation, and the piezoelectric shear deformation element in the Y-axis drive unit array generates X-axis deformation.

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