A series device for bimorph piezoelectric ceramic actuator and a cooperative control method thereof

Abstract

The application belongs to the field of precision driving and control technology, and discloses a series device for double piezoelectric ceramic actuators and a collaborative control method thereof. The double piezoelectric ceramic actuators are arranged in series, so that the effective superposition of the output displacement is realized, and a larger effective output displacement is obtained than that of a single piezoelectric ceramic actuator. A Prandtl-Ishlinskii hysteresis input-output inverse model of the first piezoelectric ceramic actuator and the second piezoelectric ceramic actuator is established, the target total output displacement is decomposed, the initial first driving voltage and the initial second driving voltage are obtained, and the control error caused by the hysteresis non-linear behavior of the double piezoelectric ceramic actuators is improved. The actual output displacement of the double piezoelectric ceramic actuators is obtained by using a rebound type displacement sensor and a laser displacement sensor, and a displacement collaborative control structure of the double piezoelectric ceramic actuators is established. The series device can accurately complete a large-stroke target output displacement and realize the collaborative cooperation of the double piezoelectric ceramic actuators.

Description

Technical Field

[0001] This invention belongs to the field of precision drive and control technology, specifically relating to a series device for dual piezoelectric ceramic actuators and its coordinated control method. Background Technology

[0002] Piezoelectric ceramic actuators possess advantages such as high displacement resolution, fast dynamic response, strong load capacity, and no electromagnetic interference, and have been widely used in precision drives, optical adjustment, active vibration reduction, and high-end equipment manufacturing. Piezoelectric ceramic actuators convert electrical signals into mechanical displacement or force output through the inverse piezoelectric effect, enabling micron-level or even nanometer-level precision drives. They are crucial actuators for achieving high-precision, high-bandwidth displacement control. However, the stroke displacement of a single piezoelectric ceramic actuator is typically limited by material strain limits, the number of stacked layers, and packaging structure, making it difficult to achieve large effective output displacement. Therefore, when the system requires large stroke micro-displacement, a single piezoelectric ceramic actuator often needs to operate at its limit drive voltage and close to its stroke limit, which can easily lead to decreased control accuracy and reduced long-term reliability.

[0003] Based on a single piezoelectric ceramic actuator, connecting two piezoelectric ceramic actuators in series along the output direction can achieve displacement superposition to a certain extent, thereby improving the effective output displacement. However, due to the harsh operating conditions of piezoelectric ceramic actuators and their inherent nonlinear behaviors such as hysteresis and creep, the series operation of two piezoelectric ceramic actuators is prone to problems such as asynchronous output displacement, inconsistent dynamic response, and unreasonable control allocation. This makes it difficult to guarantee the overall displacement accuracy and output stability of the series system, and may even lead to risks such as local overload or control oscillation due to the accumulation of displacement errors between the two actuators. Therefore, there is an urgent need to propose a series device for dual piezoelectric ceramic actuators and its coordinated control method, so that the dual piezoelectric ceramic actuators can reliably and coordinately output in terms of mechanical structure and control strategy, meeting the needs of practical engineering applications. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a series connection device for dual piezoelectric ceramic actuators and its collaborative control method. The purpose is to achieve the superposition of the output displacements of the dual piezoelectric ceramic actuators by arranging them in series along the same output direction. Simultaneously, pre-tensioning, guiding, self-aligning, and detection devices ensure the stability of the force and consistency of the output direction of the series system. Furthermore, the collaborative control method is used to coordinate the control of the dual piezoelectric ceramic actuators, adjusting their driving voltage, output displacement, and synchronization error in real time, thereby improving the output displacement, control accuracy, and operational reliability of the series connection device for dual piezoelectric ceramic actuators.

[0005] The technical solution of the present invention: A series connection device for dual piezoelectric ceramic actuators includes a series connection device base, a series connection device outer cylinder, a guide shaft, a clamping nut, a disc spring, a laser displacement sensor, a locking bolt group, a fixing bolt, a through-shaft washer-type force sensor, a force sensor mounting block, a bottom self-aligning protrusion, a first piezoelectric ceramic actuator, a floating self-aligning protrusion, a circular sleeve, a floating self-aligning concave block, a second piezoelectric ceramic actuator, a coupling self-aligning protrusion, an output shaft, a spring-loaded displacement sensor, a flexible diaphragm, a long flexible diaphragm spacer ring, a short flexible diaphragm spacer ring, an outer cylinder clamping end cap, clamping bolts, and a preload disc.

[0006] The tandem device base has a symmetrical structure and is fixed together by bolts. A through-shaft washer-type force sensor is fitted onto the reserved shaft section at the lower end of the force sensor mounting block, forming a single unit and installed in a pre-reserved circular slot at the bottom of the tandem device base. A spring-loaded displacement sensor is installed in a pre-reserved mounting hole in the tandem device base. The convex surface of the lower end of the bottom self-aligning protrusion is aligned and tightly connected to the concave surface of the upper end of the force sensor mounting block. A circular sleeve is installed at both ends of the first and second piezoelectric ceramic actuators, and the bottom self-aligning protrusion, floating self-aligning protrusion, floating self-aligning concave block, and coupling self-aligning protrusion all have circular sleeves for mounting. A first piezoelectric ceramic actuator, with circular sleeves at both ends, is mounted with one end aligned with a bottom self-aligning protrusion and the other end with a floating self-aligning protrusion. The lower surface of the floating self-aligning protrusion contacts a spring-loaded displacement sensor to measure the output displacement of the first piezoelectric ceramic actuator. A floating self-aligning concave block is mounted on the upper convex surface of the floating self-aligning protrusion, with the arcuate convex surface of the floating self-aligning protrusion and the arcuate concave surface of the floating self-aligning concave block aligned and tightly fitted. A second piezoelectric ceramic actuator, with circular sleeves at both ends, is mounted with one end aligned with the floating self-aligning concave block and the other end with a coupling self-aligning protrusion. The output shaft is mounted on the coupling self-aligning protrusion, with the arcuate convex surface of the coupling self-aligning protrusion and the output shaft... The concave surface of the arc is tightly fitted in the center; the reserved mounting hole of the base of the series device is aligned with the reserved mounting hole of the outer cylinder of the series device, and the outer cylinder of the series device is fixed to the base of the series device with fixing bolts; when the first piezoelectric ceramic actuator and the second piezoelectric ceramic actuator are actuated, the floating self-aligning protrusion, the floating self-aligning concave block and the output shaft move up and down along the inner cylinder surface of the outer cylinder of the series device; the flexible diaphragm is composed of an inner ring and an outer ring, and the inner ring and the outer ring are connected by grid bars; the flexible diaphragm, the long flexible diaphragm spacer ring, the flexible diaphragm and the short flexible diaphragm spacer ring are arranged from bottom to top on the inner stepped surface of the upper end of the outer cylinder of the series device, and the inner ring of the flexible diaphragm is sleeved on the output shaft; the inner ring of the flexible diaphragm The grid bars elastically deform as the output shaft moves up and down, ensuring that the output shaft does not move eccentrically. The outer cylinder clamping end cover is pressed onto the outer cylinder of the series device by clamping bolts, and the two flexible diaphragms, along with the long flexible diaphragm spacer ring and the short flexible diaphragm spacer ring, are pressed onto the inner stepped surface at the upper end of the outer cylinder of the series device. The two ends of the guide shaft are inserted into the reserved mounting holes in the base of the series device. The preload plate is installed close to the stepped surface of the output shaft, and is clamped by a butterfly spring and a clamping nut fitted onto the guide shaft to provide preload force. The laser displacement sensor is installed on the mounting platform of the outer cylinder of the series device using a locking bolt group to measure the displacement of the preload plate, indirectly reflecting the displacement of the output shaft.

[0007] A collaborative control method for a series device of dual piezoelectric ceramic actuators, comprising the following steps: Step 1: Calculation of driving voltage for piezoelectric ceramic actuator considering hysteresis nonlinear behavior: 1) Considering the hysteresis nonlinear behavior of the dual piezoelectric ceramic actuator, based on the displacement response of the dual piezoelectric ceramic actuator under the driving voltage, the Prandtl-Ishlinskii hysteresis input-output model of the first and second piezoelectric ceramic actuators is established. 2) Decompose the total target output displacement into the first target displacement. Second target displacement The values ​​are then assigned to the first and second piezoelectric ceramic actuators, respectively. The Prandtl-Ishlinskii hysteresis input-output models of the first and second piezoelectric ceramic actuators are inverted to obtain the corresponding Prandtl-Ishlinskii hysteresis inverse models. The first target displacement is then... Second target displacement Substituting the values ​​into the corresponding Prandtl-Ishlinskii hysteresis inverse model, we obtain the initial first driving voltage of the first piezoelectric ceramic actuator. The initial second driving voltage of the second piezoelectric ceramic actuator Based on the initial first driving voltage and initial second driving voltage The first and second piezoelectric ceramic actuators are driven to operate respectively, so that the output displacements of the first and second piezoelectric ceramic actuators are superimposed to form the actual total output displacement. .

[0008] Step 2: Real-time acquisition of displacement and force status of the dual piezoelectric ceramic actuator: 1) Using the base of the series-connected device as the displacement measurement reference, the actual displacement of the floating self-aligning protrusion is measured by the spring-loaded displacement sensor and recorded as follows: The actual total output displacement of the output shaft measured by the laser displacement sensor is denoted as... When the displacement of the base of the series device is zero, the actual output displacements of the first and second piezoelectric ceramic actuators are: in, This represents the actual output displacement of the first piezoelectric ceramic actuator. This represents the actual output displacement of the second piezoelectric ceramic actuator. 2) The preload of the first piezoelectric ceramic actuator is measured by a through-shaft shim type force sensor and recorded as follows: The through-shaft shim type force sensor ensures that the first piezoelectric ceramic actuator will not be overloaded during operation, and must meet the following requirements: in, This is the minimum allowable value of the preload. This represents the maximum permissible value of the preload.

[0009] Step 3: Establishment of a coordinated displacement control structure for dual piezoelectric ceramic actuators: 1) The target total output displacement is Based on the actual total output displacement measured by the laser displacement sensor Calculate the total displacement error : Total displacement main control loop Using PID control, the common-mode control quantity is calculated based on the total displacement error. : in, This is the proportional gain of the main control loop for total displacement. This is the integral gain of the main control loop for total displacement. The differential gain of the main control loop for total displacement. This refers to the running time of the main control loop for total displacement. For common mode control integral variables; when At that time, the total displacement main control loop Increase common mode control quantity This causes the first and second piezoelectric ceramic actuators to extend together; when At that time, the total displacement main control loop Reduce common mode control quantity This causes the first and second piezoelectric ceramic actuators to retract together. Total displacement main control loop It is mainly used to ensure that the series connection of dual piezoelectric ceramic actuators reaches the target position: 2) To prevent the first and second piezoelectric ceramic actuators from over-elongating or reaching the limit of the driving voltage prematurely, the displacement of the first and second piezoelectric ceramic actuators is balanced and coordinated. Let the displacement equilibrium error be... : Displacement Equalization Coordination Control Loop Using PID control, the differential control quantity is calculated based on the displacement equalization error. : in, The proportional gain of the control loop is used to balance displacement. To balance the integral gain of the control loop for displacement equilibrium. The differential gain of the displacement balancing control loop. The running time of the displacement balancing coordination control loop. For differential mode control integral variables; when At that time, the displacement balance coordination control loop Increase the driving force of the first piezoelectric ceramic actuator and decrease the driving force of the second piezoelectric ceramic actuator; when At that time, the displacement balance coordination control loop The drive quantity of the first piezoelectric ceramic actuator is reduced, while the drive quantity of the second piezoelectric ceramic actuator is increased, resulting in a displacement balance and coordination control loop. Used to guarantee: 3) Total displacement main control loop Output common mode control quantity Displacement balance coordination control loop Output differential control quantity The high-voltage drive control quantities of the first and second piezoelectric ceramic actuators are determined according to the following formulas: in, For the high-voltage drive control quantity of the first piezoelectric ceramic actuator, This is the high-voltage drive control quantity for the second piezoelectric ceramic actuator.

[0010] The beneficial effects of this invention are as follows: This invention proposes a series device and its coordinated control method for dual piezoelectric ceramic actuators. By arranging the dual piezoelectric ceramic actuators in series, the output displacement is effectively superimposed, achieving a larger effective output displacement compared to a single piezoelectric ceramic actuator. Furthermore, the preload plate, guide shaft, bottom self-aligning protrusion, floating self-aligning protrusion, floating self-aligning concave block, and coupling self-aligning protrusion of the series device ensure coaxial force and coaxial displacement output of the dual piezoelectric ceramic actuators, reducing the impact of off-center load and backlash on output accuracy. Simultaneously, real-time data acquisition is achieved through a spring-loaded displacement sensor and a laser displacement sensor. The displacement and force states of the dual piezoelectric ceramic actuators, combined with a displacement coordination control structure, utilize the Prandtl-Ishlinskii hysteresis input-output inverse model to mitigate control errors caused by the hysteresis nonlinearity of the dual piezoelectric ceramic actuators. Real-time compensation and adjustment are applied to the total output displacement, first target displacement, and second target displacement of the dual piezoelectric ceramic actuators. Overall, the dual piezoelectric ceramic actuators achieve reliable and coordinated output in both mechanical structure and control strategy, demonstrating strong engineering practical value and suitability for precision drive applications requiring high precision, large stroke, and micro-displacement output. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a series device for a dual piezoelectric ceramic actuator. Figure 2 A cross-sectional view of a series device for dual piezoelectric ceramic actuators; Figure 3 This is the initial drive voltage diagram calculated using the Prandtl-Ishlinskii hysteresis input-output inverse model; Figure 4 This is a diagram of the high-voltage drive control quantity of the dual piezoelectric ceramic actuator after coordinated control; Figure 5 This is a schematic diagram of the total output displacement and displacement balance coordination of the target after coordinated control.

[0012] In the figure, 1-series device base, 2-series device outer cylinder, 3-guide shaft, 4-compression nut, 5-butterfly spring, 6-laser displacement sensor, 7-locking bolt group, 8-fixing bolt, 9-through-shaft washer type force sensor, 10-force sensor mounting block, 11-bottom self-aligning protrusion, 12-first piezoelectric ceramic actuator, 13-floating self-aligning protrusion, 14-circular sleeve, 15-floating self-aligning recess, 16-second piezoelectric ceramic actuator, 17-coupling self-aligning protrusion, 18-output shaft, 19-spring-loaded displacement sensor, 20-flexible diaphragm, 21-long flexible diaphragm spacer ring, 22-short flexible diaphragm spacer ring, 23-outer cylinder compression end cap, 24-compression bolt, 25-preload disc. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0014] The installation steps for a series connection device for dual piezoelectric ceramic actuators are as follows: like Figure 1 , Figure 2As shown, the series device base 1 has a symmetrical structure and is fixed together by fixing bolts 8; the through-shaft washer type force sensor 9 is fitted onto the reserved shaft section on the lower side of the force sensor mounting block 10, and the two form a whole and are installed in the reserved circular slot at the bottom of the series device base 1; the arc convex surface at the lower end of the bottom self-aligning protrusion 11 is aligned and tightly connected with the arc concave surface at the upper end of the force sensor mounting block 10; a circular sleeve 14 is installed at both ends of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16, and the bottom self-aligning protrusion 11, the floating self-aligning protrusion 13, the floating self-aligning concave block 15, and the coupling self-aligning protrusion 17 are all provided with circular sleeves 14. Mounting slot; a first piezoelectric ceramic actuator 12 with circular sleeves 14 at both ends, one end of which is aligned with the bottom self-aligning protrusion 11, and the other end of which is mounted with a floating self-aligning protrusion 13; the lower surface of the floating self-aligning protrusion 13 contacts the spring-loaded displacement sensor 19 to measure the output displacement of the first piezoelectric ceramic actuator 12, and a floating self-aligning concave block 15 is mounted on the upper convex surface of the floating self-aligning protrusion 13, with the arcuate convex surface of the floating self-aligning protrusion 13 and the arcuate concave surface of the floating self-aligning concave block 15 aligned and tightly abutting; a second piezoelectric ceramic actuator 16 with circular sleeves 14 at both ends, one end of which is aligned with the floating self-aligning concave block 15, and the other end of which is mounted with a coupling self-aligning protrusion 17; an output shaft 18 is mounted on the coupling self-aligning protrusion 17, and the circular... The convex surface of the arc and the concave surface of the output shaft 18 are aligned and tightly abutted; the reserved mounting hole of the series device base 1 is aligned with the reserved mounting hole of the series device outer cylinder 2, and the series device outer cylinder 2 is fixed to the series device base 1 by four fixing bolts 8; when the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are actuated, the floating self-aligning protrusion 13, the floating self-aligning concave block 15 and the output shaft 18 move up and down along the inner cylinder surface of the series device outer cylinder 2; the flexible diaphragm 20 is composed of an inner ring and an outer ring, and the inner ring and the outer ring are connected by a grid; the flexible diaphragm 20, the long flexible diaphragm spacer ring 21, the flexible diaphragm 20 and the short flexible diaphragm spacer ring 22 are arranged from bottom to top on the inner stepped surface of the upper end of the series device outer cylinder 2, and the inner ring of the flexible diaphragm 20 is fitted around the output shaft. The output shaft 18 is clamped by the outer cylinder and the end cap 23, with the clamping force provided by four clamping bolts 24. The inner ring and grid of the flexible diaphragm 20 elastically deform as the output shaft 18 moves up and down, ensuring that the output shaft 18 moves without eccentricity. The guide shaft 3 is inserted into the reserved mounting holes in the base 1 of the series device at both ends. The preload plate 25 is installed close to the stepped surface of the output shaft 18 and is clamped by four sets of butterfly springs 5 ​​and clamping nuts 4 fitted on the guide shaft 3 to provide preload force for the dual piezoelectric ceramic actuator. The laser displacement sensor 6 is installed on the mounting platform of the outer cylinder 2 of the series device using the locking bolt group 7 to measure the displacement of the preload plate 25, which indirectly reflects the displacement of the output shaft 18. Thus, the series device for the dual piezoelectric ceramic actuator is installed.

[0015] A collaborative control method for a series device of dual piezoelectric ceramic actuators, comprising the following steps: Operating conditions: The operating voltages of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are... The maximum output displacement is stiffness is The target total output displacement of the series device is Sinusoidal change and operating frequency is The external load is constant. Working hours are set as ; Step 1: Calculation of driving voltage for piezoelectric ceramic actuator considering hysteresis nonlinear behavior: 1) Considering the hysteresis nonlinear behavior of the piezoelectric ceramic actuator, based on the displacement response of the two piezoelectric ceramic actuators under the driving voltage, the Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 is established. The Prandtl-Ishlinskii hysteresis input-output model is as follows: in, For the first Input voltage at any given time; For the first The predicted displacement of the Prandtl-Ishlinskii hysteresis input-output model at time t; The coefficients of the linear terms; For the Play operator; For the first The weights of each Play operator; For the first Threshold for each Play operator; The number of Play operators; The recursive formula for the Play operator is: Under this condition, the number of Play operators in the Prandtl-Ishlinskii hysteresis input-output model Let the linear term coefficients of the Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator 16, the second piezoelectric ceramic actuator 12, and the second piezoelectric ceramic actuator 16 be... The threshold values ​​of the Play operator for the Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are [0.08172231812131, 0.06722720873689], respectively. The Prandtl-Ishlinskii hysteresis input-output model for [20,62,104,146,188,230,272,314,356,398,440,482, 524,566,608,650], the first piezoelectric ceramic actuator 12, and the second piezoelectric ceramic actuator 16. The values ​​are [0.013117, 0.011328, 0.009782, 0.008448, 0.007295, 0.006300, 0.005441, 0.004699, 0.004058, 0.003504, 0.003026, 0.002613, 0.002257, 0.001949, 0.001683, 0.001453] and [0.015902, 0.013732, 0.011859, 0.010241, respectively]. 0.008844, 0.007638, 0.006596, 0.005696, 0.004919, 0.004248, 0.003668, 0.003168, 0.002736, 0.002363, 0.002040, 0.001762]. Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16. for 2) Displace the target total output Decomposed into the first target displacement Second target displacement The values ​​are assigned to the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 respectively. The Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are inverted respectively to obtain the corresponding Prandtl-Ishlinskii hysteresis input-output inverse model. Displace the first target Second target displacement Substituting the corresponding Prandtl-Ishlinskii hysteresis input-output inverse models, the initial first driving voltage of the first piezoelectric ceramic actuator 12 is obtained. The initial second driving voltage of the second piezoelectric ceramic actuator 16 ,like Figure 3 As shown; based on the initial first driving voltage and initial second driving voltage The first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are driven to actuate respectively, so that the output displacements of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are superimposed to form the actual total output displacement. .

[0016] Among them, the Prandtl-Ishlinskii hysteresis input-output inverse model: in, For the first The expected displacement at time; For the first The predicted voltage of the Prandtl-Ishlinskii hysteresis input-output inverse model at time t; For the linear terms of the Prandtl-Ishlinskii hysteresis input-output inverse model; The Play operator for the Prandtl-Ishlinskii hysteresis input-output inverse model; For the first The weights of the Play operator in the Prandtl-Ishlinskii hysteresis input-output inverse model; For the first Threshold of the Play operator for a Prandtl-Ishlinskii hysteretic input-output inverse model; The number of Play operators for the Prandtl-Ishlinskii hysteresis input-output inverse model; The recursive formula for the Play operator in the Prandtl-Ishlinskii hysteretic input-output inverse model is: Under this condition, the number of Play operators in the Prandtl-Ishlinskii hysteresis input-output inverse model Let 16 be the coefficients of the linear terms in the Prandtl-Ishlinskii hysteresis input-output inverse model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16. The threshold values ​​of the Play operator for the Prandtl-Ishlinskii hysteresis input-output inverse model of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are [12.23655940003586, 14.87492964215811], respectively. The Play operator of the Prandtl-Ishlinskii hysteresis input-output inverse model for the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 is [1.634446, 5.617700, 10.076714, 14.946588, 20.171271, 25.702361, 31.498060, 37.522269, 43.743816, 50.135780, 56.674913, 63.341138, 70.117119, 76.987881, 83.940496, 90.963797]. The weights are [-1.692415,-1.125023,-0.794667,-0.585690,-0.445326,-0.346685,-0.274884, -0.221137,-0.179982,-0.147881,-0.122453,-0.102052,-0.085507,-0.071966,-0.060799,-0.051528] and [-2.845428,-1.705475,-1.126133,-0.791838,-0.581701,-0.441217, -0.342845, -0.271441, -0.218111, -0.177352, -0.145607, -0.120494, -0.100366, -0.084057, -0.070720, -0.059727).

[0017] Step 2: Real-time acquisition of displacement and force status of the dual piezoelectric ceramic actuator: 1) Using the base 1 of the series device as the displacement measurement reference, the spring-loaded displacement sensor 19 measures the actual displacement of the floating self-aligning protrusion 13 and records it as follows: The actual total output displacement of the laser displacement sensor 6 on the output shaft 18 is recorded as follows: When the displacement of the base 1 of the series device is zero, the actual output displacements of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 are: in, This represents the actual output displacement of the first piezoelectric ceramic actuator 12. This is the actual output displacement of the second piezoelectric ceramic actuator 16; 2) The through-shaft shim type force sensor 9 measures the load force of the first piezoelectric ceramic actuator 12 and records it as follows: The through-shaft shim type force sensor 9 ensures that the first piezoelectric ceramic actuator 12 will not be overloaded during operation, and must meet the following requirements: in, and These represent the minimum and maximum allowable values ​​of preload, respectively, and have... , ; Step 3: Establishment of a coordinated displacement control structure for dual piezoelectric ceramic actuators: 1) Target total output displacement The actual total output displacement measured by laser displacement sensor 6 Calculate the total displacement error : Total displacement main control loop Using PID control, the common-mode control quantity is calculated based on the total displacement error. : in, This is the proportional gain of the main control loop for total displacement. This is the integral gain of the main control loop for total displacement. The differential gain of the main control loop for total displacement. This refers to the running time of the main control loop for total displacement. Let be the common-mode control integral variable, and we have: ; when At that time, the total displacement main control loop Increase common mode control quantity The first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 extend together; when At that time, the total displacement main control loop Reduce common mode control quantity The first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 retract together; Total displacement main control loop It is mainly used to ensure that the series connection of dual piezoelectric ceramic actuators reaches the target position: 2) To prevent the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 from over-elongating or reaching the driving voltage limit prematurely, the displacement of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 is balanced and coordinated. Let the displacement equilibrium error be... : Displacement Equalization Coordination Control Loop Using PID control, the differential control quantity is calculated based on the displacement equalization error. : in, The proportional gain of the control loop is used to balance displacement. To balance the integral gain of the control loop for displacement equilibrium. The differential gain of the displacement balancing control loop. The running time of the displacement balancing coordination control loop. For differential mode control integral variables, and have ; when At that time, the displacement balance coordination control loop Increase the driving force of the first piezoelectric ceramic actuator 12 and decrease the driving force of the second piezoelectric ceramic actuator 16; when At that time, the displacement balance coordination control loop The drive quantity of the first piezoelectric ceramic actuator 12 is reduced, while the drive quantity of the second piezoelectric ceramic actuator 16 is increased, thus achieving displacement balance and coordination control loop. Mainly used to guarantee: 3) such as Figure 4 , Figure 5 As shown, the main control loop for total displacement Output common mode control quantity Displacement balance coordination control loop Output differential control quantity The high-voltage drive control quantity of the first piezoelectric ceramic actuator 12 is obtained. High voltage drive control quantity of the second piezoelectric ceramic actuator 16 After control and adjustment, the root mean square error (RMSE) of the total output displacement of the target is only [value missing]. The root mean square error (RMSE) of the displacement equalization of the first piezoelectric ceramic actuator 12 and the second piezoelectric ceramic actuator 16 is only [value missing]. This meets the job requirements.

Claims

1. A series connection device for dual piezoelectric ceramic actuators, characterized in that, The specific structure of the series device is as follows: The base (1) of the series device is a symmetrical structure and is fixed together by fixing bolts (8); the through-shaft gasket type force sensor (9) is fitted into the reserved shaft section at the lower end of the force sensor mounting block (10), and the two form a whole and are installed in the reserved circular slot at the bottom of the series device base (1); the spring-loaded displacement sensor (19) is installed in the reserved mounting hole of the series device base (1); the arc convex surface at the lower end of the bottom self-aligning protrusion (11) is aligned with the arc concave surface at the upper end of the force sensor mounting block (10), Closely connected; a circular sleeve (14) is installed at both ends of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16); the bottom self-aligning protrusion (11), the floating self-aligning protrusion (13), the floating self-aligning concave block (15), and the coupling self-aligning protrusion (17) are all provided with mounting slots for the circular sleeve (14); the output shaft (18) is installed on the coupling self-aligning protrusion (17); the reserved mounting hole of the series device base (1) is aligned with the reserved mounting hole of the series device outer cylinder (2), and the series device is connected with the fixing bolt (8). The outer cylinder (2) is fixed on the base (1) of the series device; the flexible diaphragm (20), the long flexible diaphragm spacer (21), the flexible diaphragm (20) and the short flexible diaphragm spacer (22) are arranged from bottom to top on the inner stepped surface of the upper end of the outer cylinder (2) of the series device, and the inner ring of the flexible diaphragm (20) is sleeved on the output shaft (18); the outer cylinder clamping end cap (23) is clamped on the outer cylinder (2) of the series device by clamping bolts (24), and the two flexible diaphragms (20), the long flexible diaphragm spacer (21) and the short flexible diaphragm spacer (22) are placed on the inner stepped surface of the upper end of the outer cylinder (2) of the series device. The guide shaft (3) is pressed against the inner stepped surface of the outer cylinder (2) of the series device; both ends of the guide shaft (3) are inserted into the reserved mounting holes of the base (1) of the series device; the pre-tightening plate (25) is installed close to the stepped surface of the output shaft (18), and the pre-tightening plate (25) is pressed by the butterfly spring (5) and the clamping nut (4) fitted on the guide shaft (3) to provide pre-tightening force; the laser displacement sensor (6) is installed on the mounting platform of the outer cylinder (2) of the series device using the locking bolt group (7) to measure the displacement of the pre-tightening plate (25) and indirectly reflect the displacement of the output shaft (18).

2. The series connection device for dual piezoelectric ceramic actuators according to claim 1, characterized in that, A first piezoelectric ceramic actuator (12) with circular sleeves (14) at both ends has one end aligned with a bottom self-aligning protrusion (11) and the other end equipped with a floating self-aligning protrusion (13). The lower surface of the floating self-aligning protrusion (13) contacts a spring-loaded displacement sensor (19) to measure the output displacement of the first piezoelectric ceramic actuator (12). A floating self-aligning concave block (15) is installed on the upper convex surface of the floating self-aligning protrusion (13). The arcuate convex surface of the floating self-aligning protrusion (13) and the floating self-aligning concave block (15) are connected. The concave surface of the concave block (15) is centered and tightly connected; the second piezoelectric ceramic actuator (16) with circular sleeves (14) at both ends is installed with one end aligned with the floating self-aligning concave block (15) and the other end is equipped with a coupling self-aligning protrusion (17); when the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are actuated, the floating self-aligning protrusion (13), the floating self-aligning concave block (15) and the output shaft (18) move up and down along the inner cylinder surface of the outer cylinder (2) of the series device.

3. The series connection device for a dual piezoelectric ceramic actuator according to claim 2, characterized in that, The convex surface of the coupling self-aligning protrusion (17) and the concave surface of the output shaft (18) are aligned and closely connected.

4. The series connection device for dual piezoelectric ceramic actuators according to claim 3, characterized in that, The flexible diaphragm (20) is mainly composed of an inner ring and an outer ring, which are connected by grid bars. The inner ring and grid bars of the flexible diaphragm (20) are elastically deformed as the output shaft (18) moves up and down, ensuring that the output shaft (18) moves without eccentricity.

5. The cooperative control method for a series device for dual piezoelectric ceramic actuators according to any one of claims 1-4, characterized in that, The steps are as follows: Step 1: Calculation of driving voltage for piezoelectric ceramic actuator considering hysteresis nonlinear behavior; Step 2: Real-time acquisition of displacement and force status of dual piezoelectric ceramic actuators; Step 3: Establishment of a displacement coordination control structure for dual piezoelectric ceramic actuators.

6. The cooperative control method according to claim 5, characterized in that, The specific implementation process of the first step is as follows: 1) Considering the hysteretic nonlinear behavior of the dual piezoelectric ceramic actuators, based on the displacement response of the dual piezoelectric ceramic actuators under the driving voltage, the Prandtl-Ishlinskii hysteretic input-output model of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) is established. 2) Decompose the total target output displacement into the first target displacement. Second target displacement The values ​​are assigned to the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) respectively. The Prandtl-Ishlinskii hysteresis input-output model of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are inverted respectively to obtain the corresponding Prandtl-Ishlinskii hysteresis input-output inverse model; the first target displacement is... Second target displacement Substituting the corresponding Prandtl-Ishlinskii hysteresis input-output inverse models, the initial first driving voltage of the first piezoelectric ceramic actuator (12) is obtained. The initial second driving voltage of the second piezoelectric ceramic actuator (16) ; Based on the initial first driving voltage and initial second driving voltage The first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are driven to operate respectively, so that the output displacements of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are superimposed to form the target total output displacement.

7. The cooperative control method according to claim 6, characterized in that, The specific implementation process of the second step is as follows: 1) Using the base (1) of the series device as the displacement measurement reference, the spring-loaded displacement sensor (19) measures the actual displacement of the floating self-aligning protrusion (13) and records it as follows: The laser displacement sensor (6) measures the actual total output displacement of the output shaft (18), which is denoted as... When the displacement of the base (1) of the series device is zero, the actual output displacements of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are: in, This represents the actual output displacement of the first piezoelectric ceramic actuator (12). This is the actual output displacement of the second piezoelectric ceramic actuator (16); 2) The through-shaft shim type force sensor (9) measures the preload of the first piezoelectric ceramic actuator (12) and records it as follows: The through-shaft pad type force sensor (9) ensures that the first piezoelectric ceramic actuator (12) will not be overloaded during operation, and must meet the following requirements: in, and These represent the minimum and maximum allowable values ​​of the preload, respectively.

8. The cooperative control method according to claim 7, characterized in that, The specific implementation process of the third step is as follows: 1) Let the target total output displacement be... And based on the actual total output displacement measured by the laser displacement sensor (6) Calculate the total displacement error : Total displacement main control loop Using PID control, the common-mode control quantity is calculated based on the total displacement error. : in, This is the proportional gain of the main control loop for total displacement. This is the integral gain of the main control loop for total displacement. The differential gain of the main control loop for total displacement. This refers to the running time of the main control loop for total displacement. For common mode control integral variables; when At that time, the total displacement main control loop Increase common mode control quantity This causes the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) to extend together; when At that time, the total displacement main control loop Reduce common mode control quantity This causes the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) to retract together; the total displacement main control loop It is mainly used to ensure that the series connection of dual piezoelectric ceramic actuators reaches the target position: 2) In order to prevent the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) from over-stretching or reaching the limit of the driving voltage in advance, the displacement of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) is balanced and coordinated. Let the displacement equilibrium error be... : Displacement Equalization Coordination Control Loop Using PID control, the differential control quantity is calculated based on the displacement equalization error. : in, The proportional gain of the control loop is used to balance displacement. To balance the integral gain of the control loop for displacement balancing. The differential gain of the displacement balancing control loop. The running time of the displacement balancing coordination control loop. For differential mode control integral variables; when At that time, the displacement balance coordination control loop Increase the driving force of the first piezoelectric ceramic actuator (12) and decrease the driving force of the second piezoelectric ceramic actuator (16); when At that time, the displacement balance coordination control loop Decrease the driving force of the first piezoelectric ceramic actuator (12) and increase the driving force of the second piezoelectric ceramic actuator (16) to achieve displacement balance and coordination control loop. Used to guarantee: 3) Total displacement main control loop Output common mode control quantity Displacement balance coordination control loop Output differential control quantity The high-voltage drive control quantities of the first piezoelectric ceramic actuator (12) and the second piezoelectric ceramic actuator (16) are determined according to the following formulas: in, For the high voltage drive control quantity of the first piezoelectric ceramic actuator (12), It is the high-voltage drive control quantity for the second piezoelectric ceramic actuator (16).

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