Sandwich laminated combined positioning platform and working method thereof

Abstract

The invention discloses a sandwich laminated multi-mode rod-shaped actuator and a working method thereof, and a linear motor with a rod-shaped actuating mechanism as an actuating module, a positioning platform mechanism and a working method thereof. The rod-shaped actuating mechanism device comprises a tailstock, an output end, a piezoelectric stack and a central fastening bolt; wherein the piezoelectric stack comprises a single-partition polarized ceramic wafer, a double-partition polarized ceramic wafer and an electrode plate. According to the invention, by controlling the time sequence and frequency of the motion of the piezoelectric element in the rod-shaped actuator, the output end of the rod-shaped actuator generates periodic motion and limiting deformation in different time sequences, and the rod-shaped actuator is combined with different external mechanisms to realize multiple different motion modes. The multi-purpose actuating mechanism has the characteristic that a single actuating mechanism meets the multi-purpose actuating requirement, the linear motor has the characteristics of high reliability, large load and high precision, the positioning platform has the characteristics of fast response, high precision, active decoupling and the like, and the multi-purpose actuating mechanism is good in universality, easy to popularize and good in economic benefit.

Description

Technical Field

[0001] The present invention discloses a multi-mode rod actuator based on a sandwich laminated structure and its working method, and a linear motor, a positioning platform mechanism with the rod actuator mechanism as the actuator module and their working methods. Background Art

[0002] A linear piezoelectric drive is an actuator based on the piezoelectric effect and ultrasonic vibration. Due to its fast response speed, high precision and other characteristics, it has extremely wide applications in the fields of biology, robotics and mechanical manufacturing, especially in the application of micro-nano manipulation. However, limited by its structural and output performance limitations, it does not have the advantage of modularity, resulting in poor versatility. Therefore, how to use a single structure to cooperate with a modular external mechanism to achieve all-round and multi-purpose actuation requirements and optimize its output performance has become the main problem faced by the linear piezoelectric actuator to further broaden its application scope and improve the device performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a multi-mode rod actuator based on a sandwich laminated structure and its working method, and a linear motor, a positioning platform mechanism with the rod actuator mechanism as the actuator module and their working methods in view of the defects involved in the background art.

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

[0005] A multi-mode rod actuator based on a sandwich laminated structure, characterized in that it includes an output end, a tail seat, a piezoelectric stack and a central fastening bolt, the length dimension of the output end is significantly larger than the length dimension of the tail seat, the piezoelectric stack is arranged significantly close to the tail seat, and the fixed point position is significantly located at the tail end of the tail seat.

[0006] The tail seat is a hollow cylinder with ear-shaped bolt fixing holes and a through hole in the center;

[0007] The piezoelectric stack includes a bending piezoelectric stack and a telescopic piezoelectric stack, the bending piezoelectric stack includes a double-partitioned polarized ceramic sheet, and the telescopic piezoelectric stack includes a single-partitioned polarized ceramic sheet and an electrode sheet; both the double-partitioned polarized ceramic sheet and the single-partitioned polarized ceramic sheet are thin circular sheets with a circular hole in the center, and the double-partitioned polarized ceramic sheet has a strip-shaped non-polarized region in the center; the electrode sheet is a flat thin circular sheet with an ear-shaped protrusion with a circular hole at one end;

[0008] The output rod is a cylinder with a taper at the front end and threaded holes at both the front and the back;

[0009] The double-partition polarized ceramic sheets and electrode sheets are arranged alternately to form a bending piezoelectric stack, and the single-partition polarized ceramic sheets and electrode sheets are arranged alternately to form a telescopic piezoelectric stack. The bending piezoelectric stack and the telescopic piezoelectric stack are arranged alternately to form a piezoelectric stack. The tail-end base is connected to the piezoelectric stack, and the other side of the piezoelectric stack is connected to the non-tapered end of the output rod. The three are fixedly connected by fastening bolts, and the tail seat and the output end are clamped by a central fastening bolt to provide a clamping force for the piezoelectric stack.

[0010] The diameter dimensions of the output end and the tail seat should be slightly larger than the diameter of the ceramic sheets used, and the length dimensions can be obtained through modal calculation or modal simulation to obtain the optimal dimensions for coupling the bending mode and the longitudinal mode.

[0011] The rod-shaped actuator is a linear motor of the drive module, and is characterized by comprising a base, an actuating shaft, a cylindrical roller linear guide rail, and a piezoelectric drive module:

[0012] The actuating shaft is strip-shaped and is connected to the base through the cylindrical roller linear guide rail, so that the actuating shaft can slide freely along the cylindrical roller linear guide rail. A friction layer made of ceramic material is provided on the surface of the actuating shaft in contact with the driving foot to improve the friction performance and wear resistance.

[0013] The piezoelectric drive module comprises a rod-shaped actuator, a driving foot, an actuating rod limiter, and an elastic pre-pressure mechanism. The number and layout mode of the piezoelectric drive modules can be adjusted according to the required output speed and load.

[0014] The driving foot is umbrella-shaped, the umbrella handle is a short cylinder provided with an external thread, the rear end is connected to the rod-shaped actuator, and the front end is in close contact with the strip-shaped friction material, and materials such as ceramics are often selected as the wear-resistant materials.

[0015] The actuating rod limiter comprises a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a groove in the middle and a through hole in the center. The rotating limiter is a cuboid with a small plane extending out of the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and relatively thick and narrow sides, and a threaded hole is provided in the middle part and through holes are provided on both sides. The positioning base plate is embedded in the rotating sleeve through one relatively thick and narrow surface, and it can rotate freely around the central axis of the rotating sleeve. The other relatively thick and narrow surface of the positioning base plate abuts against the small plane of the rotating limiter extending out of the center through hole, so that it cannot rotate beyond this plane. The actuating rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively;

[0016] The elastic pre-pressure mechanism includes a spring, a bolt, and a nut; the spring is sleeved on the bolt, and the other end abuts against the thicker and narrower surface on the right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the central through hole of the small plane extended from the rotary limiter, and is fixed on the other side by the bolt to form the elastic pre-pressure mechanism;

[0017] The rod-shaped actuator is fixed on the positioning base plate through the tail-end base. The driving foot at the front end abuts against the actuating shaft, and the whole rod-shaped actuator is perpendicular to the actuating shaft; one or several rod-shaped actuators are adopted and combined with the actuating shaft in a single-side contact or opposite-side contact manner.

[0018] The rod-shaped actuator is a multi-foot linear motor of the driving module, and is characterized by including a base, an actuating shaft, a cylindrical roller linear guide rail, and a piezoelectric driving module:

[0019] The actuating shaft is strip-shaped and is connected to the base through the cylindrical roller linear guide rail, so that the actuating shaft can freely slide along the cylindrical roller linear guide rail. One actuating shaft is installed on each side of the cylindrical roller linear guide rail, and friction layers made of ceramic materials are provided on the surfaces in contact with the two driving feet to improve the friction performance and wear resistance.

[0020] The piezoelectric driving module includes a rod-shaped actuator, a driving foot, an actuating rod limiter, and an elastic pre-pressure mechanism. There are two piezoelectric driving modules, which clamp the cylindrical roller linear guide rail in the middle through a sandwich layout, and each of the two driving feet contacts the output shaft of the cylindrical roller linear guide rail. The number and layout mode of the piezoelectric driving modules can be adjusted according to the required output speed and load.

[0021] The driving foot is umbrella-shaped, the umbrella handle is a short cylinder with an external thread, the rear end is connected to the rod-shaped actuator, and the front end is in close contact with the strip-shaped friction material. Materials such as ceramics are often selected as the wear-resistant materials.

[0022] The actuating rod limiter includes a rotary sleeve, a rotary limiter, and a positioning base plate. Among them, the rotary limiter is a hollow cylinder with a slot in the middle and a through hole in the center. The rotary limiter is a cuboid extending a small plane with a central through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides; the positioning base plate is embedded in the rotary sleeve through one thicker and narrower surface, and can freely rotate around the central axis of the rotary sleeve. The other thicker and narrower surface of the positioning base plate abuts against the small plane extended from the center through hole of the rotary limiter, so that it cannot rotate beyond this plane. The actuating rod limiter is fixedly connected to the base through the rotary sleeve and the rotary limiter respectively;

[0023] The elastic pre-pressure mechanism includes a spring, a bolt, and a nut; the spring is sleeved on the bolt, and the other end abuts against the thicker and narrower surface on the right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the central through hole of the small plane extended from the rotary limiter, and is fixed on the other side by the bolt to form the elastic pre-pressure mechanism;

[0024] The rod-shaped actuator is fixed on the positioning base plate through the tail-end base, and the front-end driving foot abuts against the actuating shaft. The rod-shaped actuator is perpendicular to the actuating shaft as a whole; one or several rod-shaped actuators are used and combined with the actuating shaft in a single-sided contact or opposite-sided contact manner.

[0025] The rod-shaped actuator is a rotary motor of the driving module, and is characterized by including a base, a rotating platform, a cylindrical roller bearing, and a piezoelectric driving module:

[0026] The rotating platform is fixed to the outer ring of the cylindrical roller bearing, and the inner ring is connected to the base through a convex shaft, so that the rotating platform can freely rotate around the fixed shaft through the cylindrical roller bearing. The bottom of the rotating platform has a friction layer made of ceramic material at the contact part with the driving foot to improve the friction performance and wear resistance.

[0027] The piezoelectric driving module includes a rod-shaped actuator, a driving foot, an actuating rod limiter, and an elastic pre-pressure mechanism.

[0028] The driving foot is in an umbrella shape. The umbrella handle is a short cylinder with an external thread. The rear end is connected to the rod-shaped actuator, and the front end is in close contact with a strip-shaped friction material. Materials such as ceramics are often selected as the wear-resistant materials.

[0029] The actuating rod limiter includes a rotating sleeve, a rotary limiter, and a positioning base plate. Among them, the rotary limiter is a hollow cylinder with a groove in the middle and a through hole in the center. The rotary limiter is a cuboid with a small plane extended from the central through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through the thicker and narrower surface on one side, and can freely rotate around the central axis of the rotating sleeve. The thicker and narrower surface on the other side of the positioning base plate abuts against the small plane extended from the central through hole of the rotary limiter, so that it cannot rotate beyond this plane. The actuating rod limiter is fixedly connected to the base through the rotating sleeve and the rotary limiter respectively;

[0030] The elastic pre-pressure mechanism includes a spring, a bolt, and a nut; the spring is sleeved on the bolt, and the other end abuts against the thicker and narrower surface on the right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the central through hole of the small plane extended from the rotary limiter, and is fixed on the other side by the bolt to form the elastic pre-pressure mechanism;

[0031] The rod actuator is fixed on the positioning base plate through the tail end base, and the front end of the driving foot abuts against the actuator shaft. The whole rod actuator is perpendicular to the actuator shaft. One or several rod actuators are combined with the actuator shaft in a single-sided contact or opposite-sided contact manner.

[0032] The rod actuator is the positioning platform of the driving module, and is characterized by comprising a base, a central platform and a piezoelectric driving module; the base plate is a square plate with threaded holes opened around the center for fixing the piezoelectric driving module; the piezoelectric driving module includes four rod actuators which are distributed in a cross shape and are fixed on the base plate through bolts by the through holes at the tail ends; the central platform is a cross-shaped flat plate structure, with a relatively large positioning plane at the center, a flexible hinge structure around the periphery, and a small platform with a through hole opened at the center at the outermost end, and is fixedly connected with the threaded holes at the front ends of the rod actuators through bolts.

[0033] The present invention also discloses a working method of the sandwich laminated multi-mode rod actuator as described above, which is characterized by comprising the following three working modes:

[0034] a. Resonance working mode

[0035] If the rod actuator is required to work in the resonance mode, a high-frequency AC excitation signal is used to drive the piezoelectric stack, and the third-order bending vibration mode of the rod actuator is excited through the high-frequency deformation of the bent piezoelectric stack; the first-order longitudinal vibration mode of the rod actuator is excited through the high-frequency deformation of the longitudinal vibration stack; the two modes are superposed to form a periodic elliptical trajectory displacement at the front end of the output end.

[0036] b. Non-resonance working mode

[0037] If the rod actuator is required to work in the non-resonance mode, a low-frequency AC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bent piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted at the output end to form a periodic elliptical trajectory displacement at the front end of the output end.

[0038] c. Aperiodic working mode

[0039] If the rod actuator is required to work in the aperiodic mode, a DC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bent piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted at the output end to maintain the transverse bending deformation displacement and the longitudinal deformation displacement at the front end of the output end.

[0040] The present invention also discloses a working method of the linear motor as described above, which is characterized in that the resonance working mode of a single rod actuator can be driven by a high-frequency sine excitation to achieve a high-speed motion output, and comprises the following steps:

[0041] If it is necessary to drive the actuator shaft to move forward:

[0042] Step A.1), adjust the bolts of the elastic preloading mechanism so that the driving foot of the piezoelectric driving module applies a preloading force Fn to the actuator shaft;

[0043] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a positive cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal with a time phase difference of 90 degrees from it. During this period, the driving foot of the piezoelectric driving module is in close contact with the actuator shaft, and the actuator shaft is positively pushed by the rod-shaped actuator in the piezoelectric driving module for a distance x1 under the action of dynamic friction;

[0044] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a negative cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal with a time phase difference of 90 degrees from it. T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving foot is not actually in contact with the actuator shaft, and the actuator shaft does not move;

[0045] Step A.4), repeat steps A.2) to A.3) to make the actuator shaft move forward continuously in steps, and the step length of each cycle is x1;

[0046] If it is necessary to drive the actuator shaft to move backward:

[0047] Step A.1), adjust the bolts of the elastic preloading mechanism so that the driving foot of the piezoelectric driving module applies a preloading force Fn to the actuator shaft;

[0048] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a positive cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal with a time phase difference of -90 degrees from it. During this period, the driving foot of the piezoelectric driving module is in close contact with the actuator shaft, and the actuator shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module for a distance x1 under the action of dynamic friction;

[0049] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a negative cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal with a time phase difference of -90 degrees from it. T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving foot is not actually in contact with the actuator shaft, and the actuator shaft does not move;

[0050] Step A.4), repeat Step A.2) to Step A.3) to make the actuating shaft perform continuous reverse stepping motion, with the stepping length of each cycle being x1;

[0051] The present invention also discloses a working method of the linear motor, characterized in that a non-resonant working mode of driving a single rod-shaped actuator by a low-frequency triangular wave excitation can be adopted to achieve a higher-precision motion output, including the following steps:

[0052] If it is necessary to drive the actuating shaft to move forward:

[0053] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module all apply a pre-pressure Fn to the actuating shaft;

[0054] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with rising triangular wave signals with a frequency of K (K should be less than 20000 Hz) and rising triangular wave signals with a time phase difference of 90 degrees for T1 seconds; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is positively pushed by the rod-shaped actuator in the piezoelectric driving module by a distance of x1 under the action of static friction;

[0055] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with falling triangular wave signals with a frequency of K (K should be less than 20000 Hz) and falling triangular wave signals with a time phase difference of 90 degrees for T2 seconds, and T2 is less than T1. During this period, the driving feet of the piezoelectric driving module are actually in contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module by a distance of x2 under the action of static friction, and x2 is less than x1;

[0056] Step A.4), repeat Step A.2) to Step A.3) to make the actuating shaft perform continuous forward motion, with the stepping length of each cycle being x1 - x2;

[0057] If it is necessary to drive the actuating shaft to move backward:

[0058] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module all apply a pre-pressure Fn to the actuating shaft;

[0059] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with rising triangular wave signals with a frequency of K (K should be less than 20000 Hz) and rising triangular wave signals with a time phase difference of -90 degrees for T1 seconds; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module by a distance of x1 under the action of static friction;

[0060] Step A.3): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric drive module with a descending triangular wave signal having a frequency of K (K should be less than 20,000 Hz) and a descending triangular wave signal with a time phase difference of -90 degrees. T2 is less than T1. During this time period, the drive foot of the piezoelectric drive module is actually in contact with the actuating shaft. Under the action of static friction, the rod-shaped actuator in the piezoelectric drive module pushes the actuating shaft forward by a distance x2, and x2 is less than x1;

[0061] Step A.4): Repeat Step A.2) to Step A.3) to make the actuating shaft move continuously in the reverse direction, and the step length of each cycle is x1 - x2;

[0062] The working method of the multi-legged linear motor described in claim 1 is exactly the same as the working method of the linear motor, and the signal excitations of the rod-shaped actuators in the piezoelectric drive module are the same.

[0063] The present invention also discloses a working method of the rotary motor, which is characterized in that the resonant working mode of a single rod-shaped actuator can be driven by high-frequency sine excitation to achieve high-speed motion output, including the following steps:

[0064] If it is necessary to drive the actuating shaft to move forward:

[0065] Step A.1): Adjust the bolt of the elastic pre-pressure mechanism so that the drive foot of the piezoelectric drive module applies a pre-pressure Fn to the actuating shaft;

[0066] Step A.2): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric drive module with a positive-period sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and a descending sine wave signal with a time phase difference of 90 degrees. During this time period, the drive foot of the piezoelectric drive module is in close contact with the actuating shaft. Under the action of dynamic friction, the actuating shaft is rotated forward by an angle θ1 by the rod-shaped actuator in the piezoelectric drive module;

[0067] Step A.3): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric drive module with a negative-period sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and an ascending sine wave signal with a time phase difference of 90 degrees. T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the drive foot is actually not in contact with the actuating shaft, and the actuating shaft does not move;

[0068] Step A.4): Repeat Step A.2) to Step A.3) to make the actuating shaft move continuously in the forward step, and the step angle of each cycle is θ1;

[0069] If it is necessary to drive the actuating shaft to move backward:

[0070] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuating shaft;

[0071] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a positive-period sine wave signal with a frequency of K (K should be greater than 20000 Hz) and a rising sine wave signal with a time phase difference of -90 degrees. During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is reversely rotated by a distance θ1 by the rod-shaped actuator in the piezoelectric driving module under the action of dynamic friction;

[0072] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a negative-period sine wave signal with a frequency of K (K should be greater than 20000 Hz) and a falling sine wave signal with a time phase difference of -90 degrees. T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving feet are actually not in contact with the actuating shaft, and the actuating shaft does not move;

[0073] Step A.4), repeat steps A.2) to A.3) so that the actuating shaft makes continuous reverse step-by-step movements, and the step angle of each cycle is θ1;

[0074] The present invention also discloses a working method of the rotary motor described above, which is characterized in that a non-resonant working mode of driving a single rod-shaped actuator with a low-frequency triangular wave excitation can be adopted to achieve a high-precision motion output, including the following steps:

[0075] If it is necessary to drive the actuating shaft to move forward:

[0076] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module all apply a pre-pressure Fn to the actuating shaft;

[0077] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a rising triangular wave signal with a time phase difference of 90 degrees; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is positively rotated by a distance θ1 by the rod-shaped actuator in the piezoelectric driving module under the action of static friction;

[0078] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a descending triangular wave signal having a frequency of K (K should be less than 20,000 Hz) and a descending triangular wave signal with a 90-degree time phase difference therewith. T2 is less than T1. During this time period, the driving feet of the piezoelectric drive module are actually in contact with the actuating shaft, and the actuating shaft rotates reversely by a distance θ2 under the action of static friction. θ2 is less than θ1;

[0079] Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft move forward continuously, and the stepping length of each cycle is θ1 - θ2;

[0080] If it is necessary to drive the actuating shaft to move reversely:

[0081] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric drive module all apply a pre-pressure Fn to the actuating shaft;

[0082] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with an ascending triangular wave signal having a frequency of K (K should be less than 20,000 Hz) and an ascending triangular wave signal with a -90-degree time phase difference therewith. During this time period, the driving feet of the piezoelectric drive module are in close contact with the actuating shaft, and the actuating shaft is reversely pushed by a distance θ1 under the action of static friction;

[0083] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a descending triangular wave signal having a frequency of K (K should be less than 20,000 Hz) and a descending triangular wave signal with a -90-degree time phase difference therewith. T2 is less than T1. During this time period, the driving feet of the piezoelectric drive module are actually in contact with the actuating shaft, and the actuating shaft is positively pushed by a distance θ2 under the action of static friction. θ2 is less than θ1;

[0084] Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft move reversely continuously, and the stepping length of each cycle is θ1 - θ2;

[0085] The present invention also discloses a working method of the positioning platform described above, which is characterized in that an aperiodic working mode of driving a single rod actuator can be adopted by a DC signal excitation to achieve three-degree-of-freedom positioning, including the following steps:

[0086] Step A.1), adjust the fixed position of the bottom plate and fix the positioning platform near the position that needs precise positioning.

[0087] Step A.2), drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the x-axis direction with a DC signal to generate a constant bending deformation, drive the central platform to generate a displacement in the x-axis direction, and adjust the voltage of the input DC signal as required to meet the positioning condition in the x-axis direction.

[0088] Step A.3), drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the y-axis direction with a DC signal to generate a constant bending deformation, drive the central platform to generate a displacement in the y-axis direction, and adjust the voltage of the input DC signal as required to meet the positioning condition in the y-axis direction.

[0089] Step A.4), drive the telescopic piezoelectric stacks of all the rod-shaped actuators with a DC signal to generate a constant telescopic deformation, drive the central platform to generate a displacement in the z-axis direction, and adjust the voltage of the input DC signal as required to meet the positioning condition in the z-axis direction.

[0090] Step A.5), turn off all excitation signals, the positioning platform completes positioning, and all deformations and displacements are restored.

[0091] Compared with the prior art, the present invention adopts the above technical solutions and has the following technical effects:

[0092] 1. By separately designing the piezoelectric drive module and the actuator shaft, the output of the device can be adjusted according to different installation methods of the piezoelectric drive module and the fixing method of the actuator shaft, realizing linear output or rotational output.

[0093] 2. Since the present invention is based on piezoelectric drive technology and modularizes the piezoelectric actuators, combining the advantages of fast response, high precision, and easy control of piezoelectric drive, it realizes the modularization of the piezoelectric components for linear drive, rotational drive, and the positioning platform.

[0094] 3. The piezoelectric drive module designed in the present invention can be driven by different waveform signals and can realize two driving modes of resonance and non-resonance by using signals with different frequencies, so as to achieve the conversion between various output characteristics such as high output force, high resolution, and high speed, which has high guiding significance for the application of linear piezoelectric actuators. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 is a schematic structural diagram of the piezoelectric actuator rod of the present invention;

[0096] Figure 2 is a schematic structural diagram of the ceramic sheet in the piezoelectric actuator rod of the present invention;

[0097] Figure 3 is a schematic diagram of the multi-modular mechanism based on the piezoelectric actuator rod of the present invention;

[0098] Figure 4 It is a schematic structural diagram of the linear motion mechanism in the present invention;

[0099] Figure 5 It is a schematic structural diagram of the multi-legged linear motion mechanism in the present invention;

[0100] Figure 6 It is a schematic structural diagram of the rotary motion mechanism in the present invention;

[0101] Figure 7 It is a schematic structural diagram of the positioning platform in the present invention;

[0102] Figure 8 It is a schematic flow diagram of the working method of the linear motion mechanism in the present invention in the resonant mode;

[0103] Figure 9 It is a schematic flow diagram of the working method of the linear motion mechanism in the present invention in the non-resonant mode;

[0104] Figure 10 It is a schematic flow diagram of the working method of the rotary motion mechanism in the present invention in the resonant mode;

[0105] Figure 11 It is a schematic flow diagram of the working method of the rotary motion mechanism in the present invention in the non-resonant mode;

[0106] Figure 12 It is a schematic flow diagram of the working method of the positioning platform in the present invention;

[0107] In the figure, 1 - output end of the piezoelectric rod actuator, 2 - electrode plate of the piezoelectric rod actuator, 3 - bottom tailstock of the piezoelectric rod actuator, 4 - pre-tightening force bolt of the piezoelectric rod actuator, 5 - piezoelectric ceramic sheet of the piezoelectric rod actuator, 6 - single-zone polarized piezoelectric ceramic sheet, 7 - double-zone polarized piezoelectric ceramic sheet, 8 - piezoelectric rod actuator, 9 - rotation limiter, 10 - positioning base plate, 11 - elastic pre-pressure mechanism, 12 - positioning base plate, 13 - base of the linear motion mechanism, 14 - driving foot, 15 - cylindrical roller linear guide rail, 16 - actuating shaft, 17 - base of the multi-legged linear motion mechanism, 18 - rotating platform of the rotary motion mechanism, 19 - ball roller bearing, 20 - positioning convex shaft, 21 - base of the rotary motion mechanism, 22 - piezoelectric rod actuator, 23 - working platform of the positioning platform, 24 - base of the positioning platform. Detailed implementation manners

[0108] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings:

[0109] The present invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. On the contrary, these embodiments are provided so that this disclosure is thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0110] As Figure 1 , Figure 2 shown, a sandwich laminated multi-mode rod actuator, characterized in that it includes an output end, a tailstock, a piezoelectric stack, and a central fastening bolt. The length dimension of the output end is significantly larger than that of the tailstock, the piezoelectric stack is arranged significantly closer to the tailstock, and the fixed point position is significantly located at the tail end of the tailstock.

[0111] The tailstock is a hollow cylinder with ear-shaped bolt fixing holes and a through hole in the center;

[0112] The piezoelectric stack includes a bending piezoelectric stack and a telescopic piezoelectric stack. The bending piezoelectric stack includes a double-partition polarized ceramic sheet, and the telescopic piezoelectric stack includes a single-partition polarized ceramic sheet and an electrode sheet; both the double-partition polarized ceramic sheet and the single-partition polarized ceramic sheet are thin circular sheets with a circular hole in the center, and the double-partition polarized ceramic sheet has a strip-shaped non-polarized region in the center; the electrode sheet is a flat thin circular sheet with an ear-shaped protrusion with a circular hole at one end;

[0113] The output rod is a cylinder with a taper at the front end and threaded holes at both the front and the back;

[0114] The double-partition polarized ceramic sheets and the electrode sheets are alternately arranged to form a bending piezoelectric stack, the single-partition polarized ceramic sheets and the electrode sheets are alternately arranged to form a telescopic piezoelectric stack, and the bending piezoelectric stack and the telescopic piezoelectric stack are alternately arranged to form a piezoelectric stack; the tail end base is connected to the piezoelectric stack, the other side of the piezoelectric stack is connected to the non-tapered end of the output rod, and the three are fixedly connected by a fastening bolt, and the tailstock and the output end are clamped by a central fastening bolt to provide a clamping force for the piezoelectric stack.

[0115] The diameter dimensions of the output end and the tailstock should be slightly larger than the diameter of the ceramic sheet used, and the length dimensions can be obtained through modal calculation or modal simulation to find the optimal dimensions for coupling the bending mode and the longitudinal mode.

[0116] As Figure 3 shown, a schematic diagram of a multi-modular mechanism based on a piezoelectric actuating rod in the present invention, which respectively includes a linear motion mechanism, a rotary motion mechanism, and a positioning platform;

[0117] As Figure 4 shown, the rod actuator is a linear motor of a drive module, characterized in that it includes a base, an actuating shaft, a cylindrical roller linear guide, and a piezoelectric drive module:

[0118] The actuating shaft is strip-shaped and is connected to the base through the cylindrical roller linear guide, enabling the actuating shaft to slide freely along the cylindrical roller linear guide. A friction layer made of ceramic material is provided on the surface of the actuating shaft in contact with the driving foot to improve friction performance and wear resistance.

[0119] The piezoelectric drive module includes a rod-shaped actuator, a driving foot, an actuator rod limiter, and an elastic preloading mechanism. The quantity and layout of the piezoelectric drive modules can be adjusted according to the required output speed and load.

[0120] The driving foot is umbrella-shaped, the umbrella handle is a short cylinder with external threads, the rear end is connected to the rod-shaped actuator, and the front end is in close contact with strip-shaped friction material, and materials such as ceramics are often selected as wear-resistant materials.

[0121] The actuator rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole at the center. The rotating limiter is a cuboid with a small plane extending out of the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through one thicker and narrower side, and it can rotate freely around the central axis of the rotating sleeve. The other thicker and narrower side of the positioning base plate abuts against the small plane of the rotating limiter extending out of the center through hole, making it unable to rotate beyond this plane. The actuator rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively;

[0122] The elastic preloading mechanism includes a spring, a bolt, and a nut. The spring is sleeved on the bolt, and the other end abuts against the thicker and narrower right side surface of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the through hole at the center of the small plane of the rotating limiter extending out, and the other side is fixed by the bolt to form the elastic preloading mechanism;

[0123] The rod-shaped actuator is fixed to the positioning base plate through the tail end base, and the front end driving foot abuts against the actuating shaft. The rod-shaped actuator is perpendicular to the actuating shaft as a whole. One or several rod-shaped actuators are used and combined with the actuating shaft in a single-side contact or opposite-side contact manner.

[0124] As Figure 5 shown, the rod-shaped actuator is a multi-foot linear motor of the drive module, and is characterized in that it includes a base, an actuating shaft, a cylindrical roller linear guide, and a piezoelectric drive module:

[0125] The actuating shaft is strip-shaped and connected to the base through the cylindrical roller linear guide, enabling the actuating shaft to slide freely along the cylindrical roller linear guide. One actuating shaft is installed on each side of the cylindrical roller linear guide, and a friction layer made of ceramic material is provided on the surface in contact with the two driving feet to improve the friction performance and wear resistance.

[0126] The piezoelectric drive module includes a rod-shaped actuator, a driving foot, an actuator rod limiter, and an elastic preloading mechanism. There are two piezoelectric drive modules, which clamp the cylindrical roller linear guide in the middle through a clamp-type layout. Each driving foot contacts the output shaft of the cylindrical roller linear guide. The number and layout of the piezoelectric drive modules can be adjusted according to the required output speed and load.

[0127] The driving foot is umbrella-shaped. The umbrella handle is a short cylinder with an external thread. The rear end is connected to the rod-shaped actuator, and the front end is in close contact with the strip-shaped friction material. Materials such as ceramics are often selected as wear-resistant materials.

[0128] The actuator rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole in the center. The rotating limiter is a cuboid with a small plane extending from the center and a through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle and thicker and narrower sides, and a threaded hole is provided in the middle and through holes are provided on both sides. The positioning base plate is embedded in the rotating sleeve through one thicker and narrower side and can rotate freely around the central axis of the rotating sleeve. The other thicker and narrower side of the positioning base plate abuts against the small plane of the rotating limiter extending from the center and having a through hole, so that it cannot rotate beyond this plane. The actuator rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively;

[0129] The elastic preloading mechanism includes a spring, a bolt, and a nut. The spring is sleeved on the bolt, and the other end abuts against the thicker and narrower right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the through hole in the center of the small plane of the rotating limiter extending from the center, and the other side is fixed by the bolt to form the elastic preloading mechanism;

[0130] The rod-shaped actuator is fixed on the positioning base plate through the tail end base. The front end driving foot abuts against the actuating shaft, and the rod-shaped actuator is perpendicular to the actuating shaft as a whole. One or several rod-shaped actuators are used and combined with the actuating shaft in a single-sided contact or opposite-sided contact manner.

[0131] As Figure 6 shown, the rod-shaped actuator is a rotating motor of the drive module, which is characterized by including a base, a rotating platform, a ball roller bearing, and a piezoelectric drive module:

[0132] The rotating platform is fixed to the outer ring of the cylindrical roller bearing, and the inner ring is connected to the base through a convex shaft, so that the rotating platform can freely rotate around a fixed axis through the cylindrical roller bearing. The bottom of the rotating platform has a friction layer made of ceramic material in the contact part with the driving foot to improve the friction performance and wear resistance.

[0133] The piezoelectric drive module includes a rod-shaped actuator, a driving foot, an actuator rod limiter, and an elastic pre-pressure mechanism.

[0134] The driving foot is in an umbrella shape. The umbrella handle is a short cylinder with an external thread. The rear end is connected to the rod-shaped actuator, and the front end is in close contact with a strip-shaped friction material, and materials such as ceramics are often selected as wear-resistant materials.

[0135] The actuator rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole in the center. The rotating limiter is a cuboid with a small plane extending out of the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through a relatively thick and narrow surface on one side, and it can freely rotate around the central axis of the rotating sleeve. The relatively thick and narrow surface on the other side of the positioning base plate abuts against the small plane of the rotating limiter extending out of the center through hole, so that it cannot rotate beyond this plane. The actuator rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively;

[0136] The elastic pre-pressure mechanism includes a spring, a bolt, and a nut. The spring is sleeved on the bolt, and the other end abuts against the relatively thick and narrow surface on the right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the center through hole of the small plane extended by the rotating limiter, and the other side is fixed by the bolt to form the elastic pre-pressure mechanism;

[0137] The rod-shaped actuator is fixed to the positioning base plate through the tail end base. The front end driving foot abuts against the actuator shaft, and the whole rod-shaped actuator is perpendicular to the actuator shaft. One or several rod-shaped actuators are adopted and combined with the actuator shaft in a single-side contact or opposite-side contact manner.

[0138] Such as Figure 7As shown, the rod actuator is the positioning platform of the drive module, which is characterized by comprising a base, a central platform and a piezoelectric drive module; the base plate is a square plate with threaded holes around the center for fixing the piezoelectric drive module; the piezoelectric drive module includes four rod actuators, which are distributed in a cross shape and are fixed on the base plate through bolts by the through holes at the tail ends; the central platform is a cross-shaped flat plate structure, with a relatively large positioning plane at the center, a flexible hinge structure around the periphery, and a small platform with a through hole at the center at the outermost end, which is fixedly connected to the threaded holes at the front ends of the rod actuators through bolts.

[0139] The present invention also discloses a working method of the above-mentioned sandwich laminated multi-mode rod actuator, which is characterized by including the following three working modes:

[0140] a. Resonance working mode

[0141] If the rod actuator is required to work in the resonance mode, a high-frequency AC excitation signal is used to drive the piezoelectric stack, and the third-order bending vibration mode of the rod actuator is excited through the high-frequency deformation of the bending piezoelectric stack; the first-order longitudinal vibration mode of the rod actuator is excited through the high-frequency deformation of the longitudinal vibration stack; the two modes are superimposed to form a periodic elliptical trajectory displacement at the front end of the output end.

[0142] b. Non-resonance working mode

[0143] If the rod actuator is required to work in the non-resonance mode, a low-frequency AC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bending piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted through the output end to form a periodic elliptical trajectory displacement at the front end of the output end.

[0144] c. Aperiodic working mode

[0145] If the rod actuator is required to work in the aperiodic mode, a DC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bending piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted through the output end to maintain the transverse bending deformation displacement and the longitudinal deformation displacement at the front end of the output end.

[0146] As Figure 8 As shown, the present invention also discloses a working method of the above-mentioned linear motor, which is characterized in that the resonance working mode of a single rod actuator can be driven by a high-frequency sine excitation to achieve a high-speed motion output, including the following steps:

[0147] If it is necessary to drive the actuator shaft to move forward:

[0148] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric drive module apply a pre-pressure Fn to the actuator shaft;

[0149] Step A.2): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a positive periodic sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal having a 90-degree time phase difference therewith. During this period, the drive foot of the piezoelectric drive module is in close contact with the actuating shaft, and the actuating shaft is positively pushed forward by a distance x1 by the rod actuator in the piezoelectric drive module under the action of dynamic friction;

[0150] Step A.3): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a negative periodic sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal having a 90-degree time phase difference therewith. T2 is equal to T1. At this time, the rod actuator is in a contracted state, the drive foot has no actual contact with the actuating shaft, and the actuating shaft does not move;

[0151] Step A.4): Repeat steps A.2) to A.3) to cause the actuating shaft to perform continuous positive step motion, and the step length of each cycle is x1;

[0152] If it is necessary to drive the actuating shaft to move in the reverse direction:

[0153] Step A.1): Adjust the bolt of the elastic pre-pressure mechanism so that the drive foot of the piezoelectric drive module applies a pre-pressure Fn to the actuating shaft;

[0154] Step A.2): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a positive periodic sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal having a -90-degree time phase difference therewith. During this period, the drive foot of the piezoelectric drive module is in close contact with the actuating shaft, and the actuating shaft is reversely pushed by a distance x1 by the rod actuator in the piezoelectric drive module under the action of dynamic friction;

[0155] Step A.3): Drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a negative periodic sine wave signal having a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal having a -90-degree time phase difference therewith. T2 is equal to T1. At this time, the rod actuator is in a contracted state, the drive foot has no actual contact with the actuating shaft, and the actuating shaft does not move;

[0156] Step A.4): Repeat steps A.2) to A.3) to cause the actuating shaft to perform continuous reverse step motion, and the step length of each cycle is x1;

[0157] As Figure 9As shown, the present invention also discloses a working method of the linear motor, characterized in that a non-resonant working mode of driving a single rod-shaped actuator by a low-frequency triangular wave excitation can be adopted to achieve a higher-precision motion output, including the following steps:

[0158] If it is necessary to drive the actuator shaft to move forward:

[0159] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuator shaft.

[0160] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a rising triangular wave signal with a time phase difference of 90 degrees for T1 seconds; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuator shaft, and the actuator shaft is positively pushed by the rod-shaped actuator in the piezoelectric driving module under the action of static friction for a distance x1.

[0161] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a falling triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a falling triangular wave signal with a time phase difference of 90 degrees for T2 seconds, where T2 is less than T1. During this period, the driving feet of the piezoelectric driving module are actually in contact with the actuator shaft, and the actuator shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module under the action of static friction for a distance x2, where x2 is less than x1.

[0162] Step A.4), repeat steps A.2) to A.3) to make the actuator shaft move forward continuously, and the stepping length of each cycle is x1 - x2.

[0163] If it is necessary to drive the actuator shaft to move backward:

[0164] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuator shaft.

[0165] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a rising triangular wave signal with a time phase difference of -90 degrees for T1 seconds; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuator shaft, and the actuator shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module under the action of static friction for a distance x1.

[0166] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a descending triangular wave signal and a descending triangular wave signal with a time phase difference of -90 degrees, both with a frequency of K (K should be less than 20,000 Hz). During this time period, the drive foot of the piezoelectric drive module is actually in contact with the actuating shaft, and the actuating shaft is positively pushed forward by a distance x2 under the action of static friction, where x2 is less than x1;

[0167] Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft move continuously in the reverse direction, with a step length of x1 - x2 for each cycle;

[0168] The working method of the multi-foot linear motor described in claim 1 is exactly the same as the working method of the linear motor described above, and the signal excitations of the rod actuators in the piezoelectric drive module are all the same.

[0169] As Figure 10 shown, the present invention also discloses a working method of the rotary motor described above, which is characterized in that a resonance working mode of driving a single rod actuator can be adopted by high-frequency sine excitation to achieve a high-speed motion output, including the following steps:

[0170] If it is necessary to drive the actuating shaft to move forward:

[0171] Step A.1), adjust the bolt of the elastic pre-pressure mechanism so that the drive foot of the piezoelectric drive module applies a pre-pressure Fn to the actuating shaft;

[0172] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a positive cycle sine wave signal and a descending sine wave signal with a time phase difference of 90 degrees, both with a frequency of K (K should be greater than 20,000 Hz). During this time period, the drive foot of the piezoelectric drive module is in close contact with the actuating shaft, and the actuating shaft is positively rotated by an angle θ1 under the action of dynamic friction;

[0173] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a negative cycle sine wave signal and an ascending sine wave signal with a time phase difference of 90 degrees, where T2 is equal to T1. At this time, the rod actuator is in a contracted state, the drive foot is not actually in contact with the actuating shaft, and the actuating shaft does not move;

[0174] Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft move continuously in the forward stepwise direction, with a step angle of θ1 for each cycle;

[0175] If it is necessary to drive the actuating shaft to move in the reverse direction:

[0176] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuating shaft;

[0177] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a positive cycle sine wave signal with a frequency of K (K should be greater than 20000 Hz) and a rising sine wave signal with a time phase difference of -90 degrees. During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is reversely rotated by a distance θ1 by the rod-shaped actuator in the piezoelectric driving module under the action of dynamic friction force:

[0178] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a negative cycle sine wave signal with a frequency of K (K should be greater than 20000 Hz) and a falling sine wave signal with a time phase difference of -90 degrees. T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving feet are actually not in contact with the actuating shaft, and the actuating shaft does not move;

[0179] Step A.4), repeat steps A.2) to A.3) to make the actuating shaft perform continuous reverse step motion, and the step angle of each cycle is θ1;

[0180] As Figure 11 shown, the present invention also discloses a working method of the rotating motor described above, which is characterized in that a non-resonant working mode of driving a single rod-shaped actuator with a low-frequency triangular wave excitation can be adopted to achieve a higher-precision motion output, including the following steps:

[0181] If it is necessary to drive the actuating shaft to move forward:

[0182] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module all apply a pre-pressure Fn to the actuating shaft;

[0183] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a rising triangular wave signal with a time phase difference of 90 degrees; during this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is positively rotated by a distance θ1 by the rod-shaped actuator in the piezoelectric driving module under the action of static friction force:

[0184] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a descending triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a descending triangular wave signal with a time phase difference of 90 degrees from it. T2 is less than T1. During this period, the drive feet of the piezoelectric drive module are actually in contact with the actuating shaft, and the actuating shaft rotates reversely by a distance θ2 under the action of static friction, and θ2 is less than θ1;

[0185] Step A.4), repeat Step A.2) to Step A.3) to make the actuating shaft move forward continuously, and the step length of each cycle is θ1 - θ2;

[0186] If it is necessary to drive the actuating shaft to move reversely:

[0187] Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the drive feet of the piezoelectric drive module all apply a pre-pressure Fn to the actuating shaft;

[0188] Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a rising triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a rising triangular wave signal with a time phase difference of -90 degrees from it; during this period, the drive feet of the piezoelectric drive module are in close contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod actuator in the piezoelectric drive module by a distance θ1 under the action of static friction;

[0189] Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a descending triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a descending triangular wave signal with a time phase difference of -90 degrees from it. T2 is less than T1. During this period, the drive feet of the piezoelectric drive module are actually in contact with the actuating shaft, and the actuating shaft is positively pushed by the rod actuator in the piezoelectric drive module by a distance θ2 under the action of static friction, and θ2 is less than θ1;

[0190] Step A.4), repeat Step A.2) to Step A.3) to make the actuating shaft move reversely continuously, and the step length of each cycle is θ1 - θ2;

[0191] As Figure 12 shown, the present invention also discloses a working method of the positioning platform described above, which is characterized in that an aperiodic working mode of driving a single rod actuator by a DC signal excitation can be adopted to realize three-degree-of-freedom positioning, including the following steps:

[0192] Step A.1), adjust the fixed position of the bottom plate and fix the positioning platform near the position that needs precise positioning.

[0193] Step A.2): Drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the x-axis direction with a DC signal to generate a constant bending deformation, driving the central platform to generate a displacement in the x-axis direction. Adjust the voltage of the input DC signal as required to meet the positioning condition in the x-axis direction.

[0194] Step A.3): Drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the y-axis direction with a DC signal to generate a constant bending deformation, driving the central platform to generate a displacement in the y-axis direction. Adjust the voltage of the input DC signal as required to meet the positioning condition in the y-axis direction.

[0195] Step A.4): Drive the telescopic piezoelectric stacks of all the rod-shaped actuators with a DC signal to generate a constant telescopic deformation, driving the central platform to generate a displacement in the z-axis direction. Adjust the voltage of the input DC signal as required to meet the positioning condition in the z-axis direction.

[0196] Step A.5): Turn off all excitation signals. The positioning platform completes positioning, and all deformations and displacements are restored.

Claims

1. Sandwich laminated multi-mode rod actuator, characterized in that It includes an output end, a tailstock, a piezoelectric stack, and a central fastening bolt. The length dimension of the output end is significantly larger than that of the tailstock. The piezoelectric stack is arranged significantly closer to the tailstock, and the position of the fixed point is significantly at the end of the tailstock. The tailstock is a hollow cylinder with ear-shaped bolt fixing holes and a through hole in the center. The piezoelectric stack includes a bending piezoelectric stack and a telescopic piezoelectric stack. The bending piezoelectric stack includes a double-zone polarized ceramic sheet, and the telescopic piezoelectric stack includes a single-zone polarized ceramic sheet and an electrode sheet. Both the double-zone polarized ceramic sheet and the single-zone polarized ceramic sheet are thin circular sheets with a circular hole in the center. Among them, the double-zone polarized ceramic sheet has a strip-shaped unpolarized area in the center. The electrode sheet is a flat thin circular sheet with an ear-shaped protrusion with a circular hole at one end. The output rod is a cylinder with a taper at the front end and threaded holes at both the front and the back. The double-zone polarized ceramic sheets and the electrode sheets are arranged alternately to form a bending piezoelectric stack. The single-zone polarized ceramic sheets and the electrode sheets are arranged alternately to form a telescopic piezoelectric stack. The bending piezoelectric stack and the telescopic piezoelectric stack are arranged alternately to form a piezoelectric stack. The end base is connected to the piezoelectric stack. The other side of the piezoelectric stack is connected to the non-tapered end of the output rod. The three are fixedly connected by a fastening bolt, and the tailstock and the output end are clamped by a central fastening bolt to provide a clamping force for the piezoelectric stack. The diameter dimensions of the output end and the tailstock should be slightly larger than the diameter of the ceramic sheet used. The length dimensions can be obtained through modal calculation or modal simulation to find the optimal dimensions for coupling the bending mode and the longitudinal mode. The rod-shaped actuator is a linear motor of the drive module, which is characterized by including a base, an actuating shaft, a cylindrical roller linear guide, and a piezoelectric drive module. The actuating shaft is strip-shaped and is connected to the base through the cylindrical roller linear guide, so that the actuating shaft can slide freely along the cylindrical roller linear guide. A friction layer made of ceramic material is provided on the surface of the actuating shaft in contact with the driving foot to improve the friction performance and wear resistance. The piezoelectric drive module includes a rod-shaped actuator, a driving foot, an actuating rod limiter, and an elastic pre-pressure mechanism. The number and layout of the piezoelectric drive modules can be adjusted according to the required output speed and load. The driving foot is umbrella-shaped. The umbrella handle is a short cylinder with an external thread. The rear end is connected to the rod-shaped actuator, and the front end is in close contact with a strip-shaped friction material, and materials such as ceramics are often selected as wear-resistant materials. The moving rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole at the center. The rotating limiter is a cuboid with a small plane extending from the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle part and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through one thicker and narrower side, and it can freely rotate around the central axis of the rotating sleeve. The other thicker and narrower side of the positioning base plate abuts against the small plane of the rotating limiter extending from the center through hole, so that it cannot rotate beyond this plane. The moving rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively; The elastic pre-pressure mechanism includes a spring, a bolt, and a nut. The spring is sleeved on the bolt, and the other end abuts against the thicker and narrower right side surface of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the center through hole of the small plane extended by the rotating limiter, and the other side is fixed by the bolt to form the elastic pre-pressure mechanism; The rod-shaped actuator is fixed on the positioning base plate through the tail end base. The front end drive foot abuts against the actuating shaft, and the rod-shaped actuator is perpendicular to the actuating shaft as a whole. One or several rod-shaped actuators are used and combined with the actuating shaft in a single-side contact or opposite-side contact manner. The rod-shaped actuator is a multi-foot linear motor of the drive module, which is characterized by including a base, an actuating shaft, a cylindrical roller linear guide rail, and a piezoelectric drive module: The actuating shaft is strip-shaped and is connected to the base through the cylindrical roller linear guide rail, so that the actuating shaft can freely slide along the cylindrical roller linear guide rail. The actuating shaft is installed on both sides of the cylindrical roller linear guide rail, and a friction layer made of ceramic material is provided on the surface in contact with the two drive feet to improve the friction performance and wear resistance. The piezoelectric drive module includes a rod-shaped actuator, a drive foot, a moving rod limiter, and an elastic pre-pressure mechanism. There are two piezoelectric drive modules, which clamp the cylindrical roller linear guide rail in the middle through a clamp layout, and each drive foot contacts the output shaft of the cylindrical roller linear guide rail. The number and layout method of the piezoelectric drive modules can be adjusted according to the required output speed and load. The drive foot is umbrella-shaped, the umbrella handle is a short cylinder with an external thread, the rear end is connected to the rod-shaped actuator, and the front end is in close contact with the strip-shaped friction material. Materials such as ceramics are often selected for the material. The moving rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole in the center. The rotating limiter is a cuboid with a small plane extending from the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through a thicker and narrower side, and it can rotate freely around the central axis of the rotating sleeve. The other thicker and narrower side of the positioning base plate abuts against the small plane extending from the center through hole of the rotating limiter, so that it cannot rotate beyond this plane. The moving rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively; The elastic pre-pressure mechanism includes a spring, a bolt, and a nut. The spring is sleeved on the bolt, and the other end abuts against the thicker and narrower right side of the positioning base plate. The bolt passes through the through hole on the right side of the positioning base plate and the center through hole of the small plane extending from the rotating limiter, and the other side is fixed by the bolt to form the elastic pre-pressure mechanism; The rod-shaped actuator is fixed on the positioning base plate through the tail base. The front driving foot abuts against the actuating shaft, and the rod-shaped actuator is perpendicular to the actuating shaft as a whole. One or several rod-shaped actuators are used to combine with the actuating shaft in a single-side contact or opposite-side contact manner. The rod-shaped actuator is a rotating motor of the driving module, and is characterized by including a base, a rotating platform, a ball roller bearing, and a piezoelectric driving module: The rotating platform is fixed to the outer ring of the cylindrical roller bearing, and the inner ring is connected to the base through a convex shaft, so that the rotating platform can freely rotate around the fixed axis through the cylindrical roller bearing. The bottom of the rotating platform has a friction layer made of ceramic material at the contact part with the driving foot to improve the friction performance and wear resistance. The piezoelectric driving module includes a rod-shaped actuator, a driving foot, a moving rod limiter, and an elastic pre-pressure mechanism. The driving foot is in an umbrella shape. The umbrella handle is a short cylinder with an external thread. The rear end is connected to the rod-shaped actuator, and the front end is in close contact with a strip of friction material, and materials such as ceramics are often selected as the wear-resistant materials. The moving rod limiter includes a rotating sleeve, a rotating limiter, and a positioning base plate. Among them, the rotating limiter is a hollow cylinder with a slot in the middle and a through hole in the center. The rotating limiter is a cuboid with a small plane extending from the center through hole, and a counterbore is provided on the largest surface. The positioning base plate is a special-shaped plate with a relatively flat middle and thicker and narrower sides, and has a threaded hole in the middle and through holes on both sides. The positioning base plate is embedded in the rotating sleeve through a thicker and narrower side, and it can rotate freely around the central axis of the rotating sleeve. The other thicker and narrower side of the positioning base plate abuts against the small plane extending from the center through hole of the rotating limiter, so that it cannot rotate beyond this plane. The moving rod limiter is fixedly connected to the base through the rotating sleeve and the rotating limiter respectively; The elastic pre-pressure mechanism includes a spring, a bolt, and a nut; the spring is sleeved on the bolt, and the other end abuts against the thicker and narrower surface on the right side of the positioning base plate. The bolt passes through the through-hole on the right side of the positioning base plate and the central through-hole of the small plane extended from the rotary limiter, and is fixed on the other side by the bolt to form the elastic pre-pressure mechanism; The rod-shaped actuator is fixed on the positioning base plate through the tail-end base. The driving foot at the front end abuts against the actuating shaft, and the whole rod-shaped actuator is perpendicular to the actuating shaft. One or several rod-shaped actuators are combined with the actuating shaft in a single-side contact or opposite-side contact manner. The rod-shaped actuator is the positioning platform of the driving module, and is characterized by including a base, a central platform, and a piezoelectric driving module; the base plate is a square plate with threaded holes opened around the center for fixing the piezoelectric driving module; the piezoelectric driving module includes four rod-shaped actuators, which are distributed in a cross shape and are fixed on the base plate through bolts by the through-holes at the tail end; the central platform is a cross-shaped flat plate structure, with a larger positioning plane at the center, flexible hinge structures around the periphery, and a small platform with a through-hole opened at the outermost end, which is fixedly connected with the threaded holes at the front ends of the rod-shaped actuators through bolts.

2. The working method of the sandwich laminated multi-mode rod actuator according to claim 1, characterized in that, It includes the following three working modes: a. Resonance working mode If the rod-shaped actuator is required to work in the resonance mode, a high-frequency AC excitation signal is used to drive the piezoelectric stack, and the third-order bending vibration mode of the rod-shaped actuator is excited through the high-frequency deformation of the bent piezoelectric stack; the first-order longitudinal vibration mode of the rod-shaped actuator is excited through the high-frequency deformation of the longitudinal vibration stack; the two modes are superimposed to form a periodic elliptical trajectory displacement at the front end of the output end. b. Non-resonance working mode If the rod-shaped actuator is required to work in the non-resonance mode, a low-frequency AC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bent piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted at the output end to form a periodic elliptical trajectory displacement at the front end of the output end. c. Aperiodic working mode If the rod-shaped actuator is required to work in the aperiodic mode, a DC excitation signal is used to drive the piezoelectric stack, and the bending deformation generated by the bent piezoelectric stack and the longitudinal displacement generated by the telescopic piezoelectric stack are amplified and transmitted at the output end to maintain the lateral bending deformation displacement and longitudinal deformation displacement at the front end of the output end.

3. The working method of the linear motor according to claim 1, characterized in that The resonance working mode of driving a single rod-shaped actuator with a high-frequency sine excitation can be adopted to achieve a high-speed motion output, and it includes the following steps: If it is necessary to drive the actuating shaft to move forward: Step A.1), adjust the bolt of the elastic pre-pressure mechanism so that the driving foot of the piezoelectric driving module applies a pre-pressure Fn to the actuating shaft; Step A.2), use a positive-period sine wave signal with a frequency of K (K should be greater than 20000 Hz) and a descending sine wave signal with a time phase difference of 90 degrees from it to drive the telescopic piezoelectric stack and the bent piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module for T1 seconds. During this period, the driving foot of the piezoelectric driving module is in close contact with the actuating shaft, and the actuating shaft is positively pushed forward by a distance x1 by the rod-shaped actuator in the piezoelectric driving module under the action of dynamic friction; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a negative cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal with a time phase difference of 90 degrees. T2 is equal to T1. At this time, the rod actuator is in a contracted state, the driving foot is actually not in contact with the actuating shaft, and the actuating shaft does not move; Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft perform continuous forward stepping motion, and the stepping length of each cycle is x1; If it is necessary to drive the actuating shaft to move in the reverse direction: Step A.1), adjust the bolt of the elastic preloading mechanism so that the driving foot of the piezoelectric drive module applies a preloading force Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a positive cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal with a time phase difference of -90 degrees. During this time period, the driving foot of the piezoelectric drive module is in close contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod actuator in the piezoelectric drive module by a distance of x1 under the action of dynamic friction; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a negative cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal with a time phase difference of -90 degrees. T2 is equal to T1. At this time, the rod actuator is in a contracted state, the driving foot is actually not in contact with the actuating shaft, and the actuating shaft does not move; Step A.4), repeatedly execute Step A.2) to Step A.3) to make the actuating shaft perform continuous reverse stepping motion, and the stepping length of each cycle is x1.

4. The working method of the linear motor according to claim 1, characterized in that A non-resonant working mode of driving a single said rod actuator with a low-frequency triangular wave excitation can be adopted to achieve a higher-precision motion output, including the following steps: If it is necessary to drive the actuating shaft to move forward: Step A.1), adjust the bolt of the elastic preloading mechanism so that the driving feet of the piezoelectric drive module all apply a preloading force Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod actuator in the piezoelectric drive module with a rising triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a rising triangular wave signal with a time phase difference of 90 degrees; During this time period, the driving foot of the piezoelectric drive module is in close contact with the actuating shaft, and the actuating shaft is positively pushed by the rod actuator in the piezoelectric drive module by a distance of x1 under the action of static friction; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod actuator in the piezoelectric drive module with a falling triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a falling triangular wave signal with a time phase difference of 90 degrees. T2 is less than T1. During this time period, the driving foot of the piezoelectric drive module is actually in contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod actuator in the piezoelectric drive module by a distance of x2 under the action of static friction, and x2 is less than x1; Step A.4), repeat Steps A.2) to A.3) so that the actuating shaft moves continuously in the positive direction, and the stepping length of each cycle is x1 - x2; If it is necessary to drive the actuating shaft to move in the reverse direction: Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a rising triangular wave signal with a time phase difference of -90 degrees for T1 seconds; During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module by a distance of x1 under the action of static friction; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a falling triangular wave signal with a frequency of K (K should be less than 20,000 Hz) and a falling triangular wave signal with a time phase difference of -90 degrees for T2 seconds, where T2 is less than T1. During this period, the driving feet of the piezoelectric driving module are actually in contact with the actuating shaft, and the actuating shaft is positively pushed by the rod-shaped actuator in the piezoelectric driving module by a distance of x2 under the action of static friction, and x2 is less than x1; Step A.4), repeat Steps A.2) to A.3) so that the actuating shaft moves continuously in the reverse direction, and the stepping length of each cycle is x1 - x2; The working method of the multi-foot linear motor described in claim 1 is exactly the same as the working method of the linear motor, and the signal excitations of the rod-shaped actuators in the piezoelectric driving module are the same.

5. The working method of the rotating electrical machine according to claim 1, characterized in that, The resonance working mode of a single rod-shaped actuator can be driven by high-frequency sine excitation to achieve high-speed motion output, including the following steps: If it is necessary to drive the actuating shaft to move in the positive direction: Step A.1), adjust the bolts of the elastic pre-pressure mechanism so that the driving feet of the piezoelectric driving module apply a pre-pressure Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a positive-cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a falling sine wave signal with a time phase difference of 90 degrees for T1 seconds. During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is positively rotated by an angle of θ1 under the action of dynamic friction; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack of the rod-shaped actuator in the piezoelectric driving module with a negative-cycle sine wave signal with a frequency of K (K should be greater than 20,000 Hz) and a rising sine wave signal with a time phase difference of 90 degrees for T2 seconds, where T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving feet are not actually in contact with the actuating shaft, and the actuating shaft does not move; Step A.4), repeat Steps A.2) to A.3) so that the actuating shaft makes continuous positive stepping movements, and the stepping angle of each cycle is θ1; If it is necessary to drive the actuating shaft to move in the reverse direction: Step A.1), adjust the bolts of the elastic preloading mechanism so that the driving feet of the piezoelectric driving module apply a preloading force Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a positive cycle sine wave signal and a rising sine wave signal with a time phase difference of -90 degrees, both having a frequency of K (K should be greater than 20,000 Hz). During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is reversely rotated by a distance θ1 under the action of dynamic friction by the rod-shaped actuator in the piezoelectric driving module; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a negative cycle sine wave signal and a falling sine wave signal with a time phase difference of -90 degrees, both having a frequency of K (K should be greater than 20,000 Hz). T2 is equal to T1. At this time, the rod-shaped actuator is in a contracted state, the driving feet are not actually in contact with the actuating shaft, and the actuating shaft does not move; Step A.4), repeat Step A.2) to Step A.3) so that the actuating shaft makes continuous reverse step motions, and the step angle of each cycle is θ1.

6. The working method of the rotating electrical machine according to claim 1, characterized in that The non-resonant working mode of driving a single said rod-shaped actuator can be realized by using a low-frequency triangular wave excitation, including the following steps: If it is necessary to drive the actuating shaft to move forward: Step A.1), adjust the bolts of the elastic preloading mechanism so that the driving feet of the piezoelectric driving module apply a preloading force Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal and a rising triangular wave signal with a time phase difference of 90 degrees, both having a frequency of K (K should be less than 20,000 Hz); During this period, the driving feet of the piezoelectric driving module are in close contact with the actuating shaft, and the actuating shaft is positively rotated by a distance θ1 under the action of static friction by the rod-shaped actuator in the piezoelectric driving module; Step A.3), drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module with a falling triangular wave signal and a falling triangular wave signal with a time phase difference of 90 degrees, both having a frequency of K (K should be less than 20,000 Hz). T2 is less than T1. During this period, the driving feet of the piezoelectric driving module are actually in contact with the actuating shaft, and the actuating shaft is reversely rotated by a distance θ2 under the action of static friction by the rod-shaped actuator in the piezoelectric driving module, and θ2 is less than θ1; Step A.4), repeat Step A.2) to Step A.3) so that the actuating shaft makes continuous forward motions, and the step length of each cycle is θ1 - θ2; If it is necessary to drive the actuating shaft to move backward: Step A.1), adjust the bolts of the elastic preloading mechanism so that the driving feet of the piezoelectric driving module apply a preloading force Fn to the actuating shaft; Step A.2), drive the telescopic piezoelectric stack and the bending piezoelectric stack T1 seconds of the rod-shaped actuator in the piezoelectric driving module with a rising triangular wave signal and a rising triangular wave signal with a time phase difference of -90 degrees, both having a frequency of K (K should be less than 20,000 Hz); During this period, the driving foot of the piezoelectric driving module is in close contact with the actuating shaft, and the actuating shaft is reversely pushed by the rod-shaped actuator in the piezoelectric driving module by a distance θ1 under the action of static friction force. In step A.3), a descending triangular wave signal with a frequency of K (K should be less than 20000 Hz) and a descending triangular wave signal with a time phase difference of -90 degrees are used to drive the telescopic piezoelectric stack and the bending piezoelectric stack T2 seconds of the rod-shaped actuator in the piezoelectric driving module. T2 is less than T1. During this period, the driving foot of the piezoelectric driving module is actually in contact with the actuating shaft, and the actuating shaft is positively pushed by the rod-shaped actuator in the piezoelectric driving module by a distance θ2 under the action of static friction force, and θ2 is less than θ1. In step A.4), steps A.2) to A.3) are repeatedly executed to make the actuating shaft move continuously in the reverse direction, and the step length of each cycle is θ1 - θ2.

7. The working method of the positioning platform according to claim 1, characterized in that, The aperiodic working mode of driving a single said rod-shaped actuator can be realized by using a DC signal excitation, including the following steps: In step A.1), adjust the fixed position of the bottom plate and fix the positioning platform near the position to be precisely positioned. In step A.2), use a DC signal to drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the x-axis direction to generate a constant bending deformation, drive the central platform to generate a displacement in the x-axis direction, and adjust the voltage of the input DC signal according to the requirement to meet the positioning condition in the x-axis direction. In step A.3), use a DC signal to drive the bending piezoelectric stacks of the two rod-shaped actuators arranged in the y-axis direction to generate a constant bending deformation, drive the central platform to generate a displacement in the y-axis direction, and adjust the voltage of the input DC signal according to the requirement to meet the positioning condition in the y-axis direction. In step A.4), use a DC signal to drive the telescopic piezoelectric stacks of all the rod-shaped actuators to generate a constant telescopic deformation, drive the central platform to generate a displacement in the z-axis direction, and adjust the voltage of the input DC signal according to the requirement to meet the positioning condition in the z-axis direction. In step A.5), turn off all excitation signals, the positioning platform completes positioning, and all deformations and displacements are restored.

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