Piezoelectric transducer control method based on LADRC controller parameter self-adaption

Abstract

The invention discloses a piezoelectric transducer control method based on LADRC controller parameter self-adaption, and the method comprises the steps: constructing an equivalent electrical model of a piezoelectric transducer, inputting voltage excitation into the equivalent electrical model, and obtaining the voltage response and current response of the equivalent electrical model; respectively inputting the voltage response and the current response into a model identification tool box to obtain a piezoelectric transducer transfer function; based on the transfer function of the piezoelectric transducer, calculating to obtain the phase difference and the current effective value between the voltage signal and the current signal at the output end of the equivalent electrical model; and inputting the phase difference and the current effective value into an LADRC controller subjected to parameter setting to generate a control signal, and driving the piezoelectric transducer to operate in a resonant state through the control signal. According to the method, the controlled object piezoelectric transducer is simplified into a transfer function of the piezoelectric transducer, LADRC controller parameters are simplified, automation of the whole parameter setting process is achieved, and a large amount of time is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric transducer output control, and in particular to a piezoelectric transducer control method based on LADRC controller parameter adaptation. Background Art

[0002] Piezoelectric transducers are devices that work based on the piezoelectric effect. The positive piezoelectric effect refers to the phenomenon that when a crystal is subjected to an external force in a fixed direction, charges of opposite signs are generated on two surfaces; the reverse piezoelectric effect refers to the phenomenon that an alternating electric field is applied to the crystal to cause mechanical deformation of the crystal. Using these effects, piezoelectric transducers can realize the conversion between electrical energy and mechanical energy (or sound energy).

[0003] Piezoelectric transducers are widely used in ultrasonic processing, ultrasonic cleaning, ultrasonic detection, testing, monitoring, telemetry, remote control and other fields. For example, piezoelectric ceramic transformers, ultrasonic motors, ultrasonic cleaning equipment, ultrasonic welding equipment, etc. all use the principle of piezoelectric transducers. These applications put forward different requirements on the performance of piezoelectric transducers, thus promoting the development of piezoelectric transducer control strategies.

[0004] In order to ensure the economy and effectiveness of using piezoelectric transducers, piezoelectric transducers need to maintain high energy conversion efficiency and reduce heat loss during operation. According to the characteristics of piezoelectric transducers, the frequency of the excitation voltage should be the same as the natural frequency of the piezoelectric ceramic inside the piezoelectric transducer. At this time, the piezoelectric ceramic will resonate and reach a resonant state. At this time, the piezoelectric transducer is purely resistive to the outside, with the lowest impedance and the highest energy conversion efficiency. At the same time, according to different usage requirements, the piezoelectric transducer needs to output the corresponding power. When the excitation voltage maintains the same frequency, the impedance of the piezoelectric transducer will not change. At this time, the output power is proportional to the effective value of the current.

[0005] In different usage scenarios, the models of piezoelectric transducers are different. Even the same model of piezoelectric transducers may have slightly different characteristics due to differences in manufacturing processes. Therefore, it is necessary to adjust the controller parameters for different piezoelectric transducers. In the past, the adjustment process was mostly performed manually, which consumed a lot of energy and time, and there was no unified measurement standard for the adjustment results. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a piezoelectric transducer control method based on LADRC controller parameter adaptation, the method comprising:

[0007] S1: construct an equivalent electrical model of the piezoelectric transducer, and input voltage excitation into the equivalent electrical model to obtain its voltage response and current response;

[0008] S2: inputting the voltage response and the current response into a model identification toolbox respectively to obtain a piezoelectric transducer transfer function;

[0009] S3: Based on the transfer function of the piezoelectric transducer, the phase difference between the voltage signal and the current signal at the output end of its equivalent electrical model and the effective value of the current are calculated;

[0010] S4: Input the phase difference and the effective value of the current into the LADRC controller after parameter adjustment to generate a control signal, and drive the piezoelectric transducer to operate in a resonant state through the control signal.

[0011] Furthermore, the LADRC controller parameters are adjusted by the PSO optimization algorithm, and the specific process includes:

[0012] Initialize the seed population, each particle represents a set of possible parameters (ω o ,ω c , b0), where ω o represents the bandwidth of the linear extended state observer in the LADRC controller, b0 represents the compensation coefficient of the LADRC controller, ω c Represents the gain coefficient, which determines the initial position and velocity of each particle. The position vector of each particle corresponds to the parameter value of the LADRC controller, and the velocity vector of each particle represents the direction and magnitude of the change of the parameter value;

[0013] The fitness value of each particle is calculated according to the fitness function, and the fitness function is specifically:

[0014]

[0015] In the formula, J ITAE It represents the product of the absolute value of the error and the time integrated over time, t represents the time, and e(t) represents the error between the target signal and the output signal of the piezoelectric transducer at time t.

[0016] Update the individual optimal solution of each particle and the global optimal solution of the entire particle swarm respectively;

[0017] Iteratively update the speed and position of each particle until the iteration termination condition is reached, and output the parameter value of the LADRC controller corresponding to the historical optimal position of the group

[0018] Beneficial effects of the present invention: The present invention constructs a simplified model of the piezoelectric transducer, and constructs the piezoelectric transducer transfer function based on it, which can better track the change of the resonant frequency of the transducer, adaptively optimize the LADRC controller parameters through the PSO optimization algorithm, continuously optimize the control signal of the piezoelectric transducer, adjust the driving frequency, stabilize the energy output of the transducer, make the transducer work in the resonant frequency state, effectively extend the life of the transducer, and improve the energy conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flowchart of steps of an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the equivalent electrical model structure of the piezoelectric transducer in an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of a process of establishing a piezoelectric transducer transfer function in an embodiment of the present invention;

[0022] Figure 4 Schematic diagram of a process for calculating a phase difference in an embodiment of the present invention;

[0023] Figure 5 Schematic diagram of the structure of the LADRC controller in an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the operation process of adjusting the piezoelectric transducer by the LADRC controller in an embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the process of adjusting the LADRC controller parameters by PSO optimization algorithm in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances. This is just a way of distinguishing objects with the same attributes when describing the embodiments of this application.

[0027] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0028] Terminology explanation:

[0029] PSO (Particle Swarm Optimization) algorithm: particle swarm optimization algorithm;

[0030] LADRC (Linear Active Disturbance Rejection Control) controller: Linear Active Disturbance Rejection Controller;

[0031] Reference Figure 1 As shown, an embodiment of the present invention provides a piezoelectric transducer control method based on LADRC controller parameter adaptation, the method comprising:

[0032] S1: Construct an equivalent electrical model of the piezoelectric transducer, and input voltage excitation into the equivalent electrical model to obtain its voltage response and current response.

[0033] The Mason model can be a physical model of a film bulk acoustic resonator (FBAR). An equivalent electrical model of a piezoelectric transducer is constructed based on the Mason model.

[0034] Figure 2 Schematic diagram of the equivalent electrical model structure of the piezoelectric transducer in an embodiment of the present invention.

[0035] In some preferred embodiments, the equivalent electrical model of the piezoelectric transducer is specifically a parallel circuit. Figure 2 As shown, the parallel circuit is specifically: a capacitor C0 is connected in parallel with an RLC series circuit; the RLC series circuit is specifically: a capacitor C1, an inductor L1 and a resistor R1 are connected in series. Specifically, the capacitor C0 in the parallel circuit represents the equivalent capacitance of the piezoelectric vibrator in static state; in the RLC series circuit, the capacitor C1 is the dynamic equivalent capacitance generated by the elastic vibration of the transducer, the resistor R1 reflects the dynamic mechanical damping, including load loss and mechanical loss, and the inductor L1 is a dynamic equivalent inductance, which is related to the quality characteristics of the transducer.

[0036] The piezoelectric transducer equivalent electrical model is a general method for constructing a model for a piezoelectric transducer, that is, for piezoelectric transducers of different models, the circuit structure of the equivalent electrical model is the same, but the parameters are different, that is, the values ​​of the capacitor C0, the capacitor C1, the resistor R1 and the inductor L1 are different.

[0037] The voltage excitation is generated by a frequency sweep module, which is specifically a sine wave with variable frequency; the sine wave is converted into a voltage signal through a voltage-controlled voltage source module, and the voltage signal is connected to both ends of the piezoelectric transducer equivalent electrical model, and the output end of the piezoelectric transducer equivalent electrical model outputs its voltage response and current response.

[0038] S2: Input the voltage response and the current response into the model identification toolbox respectively to obtain the piezoelectric transducer transfer function.

[0039] Figure 3 Schematic diagram of the process of establishing a piezoelectric transducer transfer function in an embodiment of the present invention.

[0040] Taking the simulink environment as a specific example, the specific steps of establishing the transfer function of the piezoelectric transducer are explained.

[0041] In some preferred embodiments, reference Figure 3 As shown in Figure 1, the specific process of establishing the transfer function of the piezoelectric transducer includes:

[0042] S101: Setting the initial frequency and the cutoff frequency, that is, the frequency sweep range, through the frequency sweep module. The frequency sweep range should include the resonant frequency of the piezoelectric transducer.

[0043] To ensure accurate results, the sweep frequency range should not be too large or too small, generally 2kHz, and the sweep time is also set. For example, if the resonant frequency of a certain type of piezoelectric transducer is 55.718kHz, then the initial frequency is set to 55khz, the cutoff frequency is 57khz, and the sweep time is 2 seconds, which means that the generated frequency gradually increases from 55khz to 57khz. The frequency is positively linearly correlated with time.

[0044] S102: Input the variable frequency sine wave generated by the frequency sweep module to the voltage-controlled voltage source module to generate a voltage-controlled voltage source, and connect the voltage signal output by the voltage-controlled voltage source to both ends of the piezoelectric transducer equivalent circuit; respectively set a voltage acquisition module and a current acquisition module at both ends of the RLC series circuit in the equivalent circuit to acquire the voltage response and current response thereof.

[0045] S103: Taking the voltage excitation output by the voltage-controlled voltage source as input and the collected voltage response as output, the gain transfer function of the piezoelectric transducer is obtained through the model identification toolbox; taking the voltage excitation output by the voltage-controlled voltage source as input and the collected current response as output, the impedance transfer function of the piezoelectric transducer is obtained through the model identification toolbox.

[0046] In some preferred embodiments, the piezoelectric transducer transfer function includes a piezoelectric transducer gain transfer function and a piezoelectric transducer impedance transfer function.

[0047] S3: Based on the transfer function of the piezoelectric transducer, the phase difference between the voltage signal and the current signal at the output end of its equivalent electrical model and the effective value of the current are calculated.

[0048] Figure 4 The figure is a schematic diagram of a process of calculating a phase difference in an embodiment of the present invention.

[0049] In some preferred embodiments, reference Figure 4As shown, the phase difference between the voltage signal and the current signal at the output end of the equivalent electrical model and the effective value of the current are calculated. The specific process includes:

[0050] S301 signal sampling: sampling the voltage signal and current signal at the output end of the equivalent electrical model to obtain voltage or current discrete signals respectively. Sampling rate f s It should comply with Nyquist theorem.

[0051] S302 Fast Fourier Transform FFT: intercept N data of the voltage or current discrete signal respectively to perform Fast Fourier Transform, convert it from the time domain to the frequency domain, and calculate the phase spectrum of the voltage or current discrete signal at the discrete frequency.

[0052] S303 determines the index of the resonance frequency: searching for the index position corresponding to the resonance frequency in the phase spectrum of the voltage or current discrete signal.

[0053] The index calculation formula is:

[0054]

[0055] In the formula, Δf represents the frequency resolution, Δf represents the ability to separate two adjacent spectrum peaks in the frequency domain; f s is the signal sampling frequency, and N represents the data size required for a fast Fourier transform FFT.

[0056] For example, the resonant frequency of a piezoelectric transducer is 55718 Hz, so f s =7131904, N=2048, Δf=3482, index 16, the frequency corresponding to the 16th index on the phase spectrum is 55718Hz. N value of 2 can speed up the operation. When N is too large, the operation speed will be slow. When N is too small, Δf will be large, and the corresponding resonant frequency point cannot be found in the phase spectrum. s If it is too large, Δf will also become larger, f s If it is too small, the sampled signal will be distorted.

[0057] S304 Calculate the phase difference: obtain the phase difference between the voltage signal and the current signal by calculating the phase value of the corresponding index in the phase spectrum.

[0058] Figure 5 Schematic diagram of the structure of the LADRC controller in an embodiment of the present invention. Figure 5In the method, voltage excitation is input to the piezoelectric transducer to obtain the voltage response and current response of its output, which are input to the LADRC controller, and the state signal is output by the linear extended state observer, which is compared with the target signal, and the comparison result is input to the PD control combination, and the output of the PD control combination is compensated by the compensation coefficient, and the compensated output result is fed back to the linear extended state observer and used as the control signal, which is used as the input excitation of the piezoelectric transducer. The target signal refers to the signal that the piezoelectric transducer is expected to work in a resonant state and the signal that the piezoelectric transducer is expected to output a certain power. The target signal does not act directly on the piezoelectric transducer, but generates a control signal through the LADRC controller, and the piezoelectric transducer is driven or controlled by the control signal. The target signal includes two parts. One is the phase difference between the voltage signal and the current signal. In order to make the piezoelectric transducer work in a resonant state, the phase difference between the voltage signal and the current signal needs to be 0 degrees. At this time, the equivalent model of the piezoelectric transducer (i.e., the equivalent circuit) is purely resistive to the outside. The frequency of the excitation voltage is adjusted by the LADRC controller to maintain the phase difference between the voltage signal and the current signal at 0 degrees. The second is the effective value of the current. Under different requirements, the piezoelectric transducer needs to maintain different output powers, P = I 2 R, the output power is related to the effective value of the current and the impedance. When the piezoelectric transducer works in a resonant state, the impedance remains unchanged. At this time, the effective value of the current can be changed by adjusting the amplitude of the excitation voltage through the LADRC controller, so that the piezoelectric transducer maintains the required output power.

[0059] In order to ensure the energy conversion efficiency, the piezoelectric transducer needs to work in a resonant state (i.e. the target state to be achieved). Therefore, the output characteristics of the piezoelectric transducer need to be controlled by a control signal to be infinitely close to the target signal. The voltage and current phase difference in the target signal can be set to 0 degrees in an ideal state, when the piezoelectric transducer works in a resonant state. However, in actual control, due to the interference of external factors such as load, this value can be adjusted according to the actual situation and is not limited to 0 degrees; the effective value of the current in the target signal, since the output power of the piezoelectric transducer is proportional to the effective value of the current, can be determined according to the impedance of the piezoelectric transducer working in a resonant state and the output power requirements to determine its set value.

[0060] The calculation method of the effective value of the current is as follows. It is known that the average power of a sinusoidal current in one cycle is equal to the square of its effective value divided by the resistance, and the average power is equal to the square of the peak current divided by 2 and then divided by the resistance. Since the current signal in the output response of the piezoelectric transducer is a sine wave, its effective value can be calculated by the following formula:

[0061]

[0062] In the formula, Irms Indicates the effective value of current, I m Indicates the instantaneous maximum current value (peak value) in AC power.

[0063] In some preferred embodiments, reference Figure 5 As shown, the LADRC controller includes a linear extended state observer, a PD control combination and a compensation coefficient b0. The linear extended state observer obtains the state signal of the system by receiving the input and output of the piezoelectric transducer, and the PD control combination obtains the control signal of the system by receiving the difference between the target signal and the state signal. The compensation coefficient b0 is determined by the characteristics of the piezoelectric transducer and is used to make the control process more stable and avoid oscillation.

[0064] The linear extended state observer includes β 01 ,β 02 ,β 03 The three parameters can be designed based on the concept of observer bandwidth. Generally speaking, β 01 =3ω o , Among them, ω o represents the bandwidth of the linear extended state observer; k p , k d is the gain parameter of the PD control combination, where k p =2ω c , ω c represents the gain coefficient. Therefore, the simplified LADRC controller parameters only need to be adjusted ω o ,ω c , b0 and three parameters are enough.

[0065] S4: Input the phase difference and the effective value of the current into the LADRC controller after parameter adjustment to generate a control signal, and drive the piezoelectric transducer to operate in a resonant state through the control signal.

[0066] Figure 6 Schematic diagram of the operation process of adjusting the piezoelectric transducer by the LADRC controller in an embodiment of the present invention. Figure 6In the method, the excitation voltage is input into the piezoelectric transducer transfer function, which includes the piezoelectric transducer impedance transfer function and the piezoelectric transducer gain transfer function. The current signal is output through the piezoelectric transducer impedance transfer function, and the voltage signal is output through the piezoelectric transducer gain transfer function. The phase difference and the effective value of the current between the voltage signal and the current signal output by the piezoelectric transducer are calculated. The parameters of the LADRC controller (LADRC frequency controller and LADRC amplitude controller, respectively) are optimized by the PSO optimization algorithm. After being processed by the LADRC frequency controller, the excitation voltage frequency is output; after being processed by the LADRC amplitude controller, the excitation voltage amplitude is output. The excitation voltage (i.e., the control signal) is composed of the excitation voltage frequency and the excitation voltage amplitude.

[0067] In some preferred embodiments, a control signal is generated by a LADRC controller, and the operation of the piezoelectric transducer is driven by the control signal, wherein the process includes a frequency controller and an amplitude controller.

[0068] Reference Figure 5 , 6 As shown, the control process of the frequency controller includes:

[0069] S401: Input the calculated voltage signal, the phase difference between the current signal and the excitation voltage frequency into the linear extended state observer respectively to obtain the piezoelectric transducer state signal at the current moment.

[0070] S402: Compare the piezoelectric transducer state signal with the target signal to obtain a phase difference error signal between the voltage signal and the current signal.

[0071] S403: The phase difference error signal is combined by PD control and a compensation coefficient b0 to obtain a frequency real-time control signal;

[0072] S404: driving the piezoelectric transducer to operate in a resonant state through a frequency real-time control signal.

[0073] Reference Figure 5 , 6 As shown in Figure 2, the control process of the amplitude controller includes:

[0074] S411: The calculated current effective value and excitation voltage amplitude are input into the linear extended state observer respectively to obtain the piezoelectric transducer state signal at the current moment;

[0075] S412: Compare the state signal with the target signal to obtain a current effective value error signal;

[0076] S413: The current effective value error signal is combined with the PD control and the compensation coefficient b0 to obtain an amplitude real-time control signal;

[0077] S414: driving the piezoelectric transducer to operate in a resonant state through a real-time amplitude control signal.

[0078] The LADRC controller has 6 adjustable parameters. In order to speed up the parameter setting of the PSO optimization algorithm, the parameters that need to be set are simplified here. The linear extended state observer includes β 01 ,β 02 ,β 03 The three parameters are simplified by introducing the concept of observer bandwidth through pole placement method. Let β 01 =3ω o , where ω o is the observer bandwidth; k p , k d is the gain parameter of the PD control combination. According to the characteristics of the PD control combination, let k p =2ω c , So after simplification, the parameter adjusted by PSO optimization algorithm is ω o ,ω c , b0.

[0079] Figure 7 Schematic diagram of the process of adjusting the LADRC controller parameters by PSO optimization algorithm in an embodiment of the present invention.

[0080] In some preferred embodiments, reference Figure 7 As shown in the figure, the LADRC controller parameters are adjusted by the PSO optimization algorithm. The specific process includes:

[0081] S501: Initialize the seed population, each particle represents a set of possible parameters (ω o ,ω c , b0), determine the initial position and velocity of each particle. The position vector of each particle corresponds to the parameter value of the LADRC controller, and the velocity vector of each particle represents the direction and magnitude of the change of the parameter value.

[0082] Specifically, a set of particles are randomly generated in the search space, each particle represents a set of possible parameters (ω o ,ω c , b0). The particle position vector corresponds to the parameter value of the LADRC controller, and the velocity vector represents the direction and magnitude of the parameter value change.

[0083] S502: Calculate the fitness value of each particle according to the fitness function.

[0084] Specifically, for each particle, its parameter value is substituted into the LADRC controller, and the simulation system is run to calculate the fitness value. The fitness value is calculated according to the objective function of the optimization problem. The objective function uses the absolute value of error and time integral type (ITAE) as the fitness function for optimization, and its form is:

[0085]

[0086] In the formula, J ITAE It represents the product of the absolute value of the error and time integrated over time, t represents time, and e(t) represents the error between the target signal and the output signal of the piezoelectric transducer at time t.

[0087] S503: Update the individual optimal solution of each particle and the global optimal solution of the entire particle swarm respectively.

[0088] Specifically, update the individual optimal solution of each particle: for each particle, compare the fitness value of its current position with the fitness value of its individual historical optimal position. If the current position is better, update the individual optimal solution.

[0089] Update the global optimal solution of the entire particle swarm: In the entire particle swarm, compare the fitness values ​​of the individual optimal solutions of all particles, find the global optimal solution, and update the group optimal solution.

[0090] S504: Iteratively update the speed and position of each particle.

[0091] Specifically, for each particle, its velocity and position are updated according to the following formula:

[0092] The velocity update formula for each particle is:

[0093]

[0094] In the formula, represents the velocity vector of particle i in the dth dimension in the k+1th iteration, k represents the number of iterations, ω represents the inertia weight, represents the velocity vector of particle i in the dth dimension in the kth iteration, c1 represents the individual learning factor, represents the historical optimal position of particle i in the dth dimension in the kth iteration, represents the position vector of particle i in the dth dimension in the kth iteration, c2 represents the group learning factor, represents the historical optimal position of the d-th dimension of the population in the k-th iteration, and r1 and r2 represent random numbers in the interval [0,1].

[0095] The position update formula for each particle is:

[0096]

[0097] In the formula, represents the position vector of particle i in the k+1th iteration, represents the position vector of particle i in the k+1th iteration, represents the velocity vector of the dth dimension of particle i in the k+1th iteration;

[0098] N is the size of the particle group, i is the particle number, i = 1, 2, ..., N;

[0099] D is the particle dimension, d is the particle dimension number, d = 1, 2, ..., D, here a set of LADRC controller parameters is three, so each particle dimension is three-dimensional;

[0100] k is the number of iterations, which is one of the conditions for terminating the iteration to prevent the algorithm from entering an unsolvable loop state;

[0101] ω is the inertia weight, which is used to control the influence of the previous speed on the current speed. In order to ensure the convergence accuracy, the inertia weight is reduced in a decreasing manner, that is, as the number of iterations increases, the inertia weight gradually decreases.

[0102] S505: Iteration termination condition:

[0103] Repeat steps S502-S504, and determine whether the termination condition is met based on the current number of iterations and the fitness value. If the number of iterations reaches the maximum number of iterations, or the fitness value corresponding to the global optimal particle reaches the preset value, the algorithm ends.

[0104] S506: Output result:

[0105] At the end of the algorithm, the parameter value of the LADRC controller corresponding to the historical optimal position of the group is output, which is the optimized parameter.

[0106] Reference Figure 5 , 6 As shown, the present invention sweeps the frequency of the equivalent electrical model of the piezoelectric transducer, inputs the excitation and response into the model identification toolbox respectively, obtains the piezoelectric transducer transfer function, obtains the voltage signal and current signal at the output end of the piezoelectric transducer through the piezoelectric transducer transfer function, calculates the phase difference between the voltage signal and the current signal at the resonant frequency point using the fast Fourier algorithm, uses the phase difference and the current effective value as the state input of the frequency controller and the amplitude controller respectively, obtains the real-time control signal through the PD control combination and the compensation coefficient b0 to control the piezoelectric transducer, and makes the piezoelectric transducer work in the resonant state. At the same time, the PSO optimization algorithm is introduced to adjust the parameters of the LADRC controller, which enhances the stability of the control system for different controlled objects.

[0107] The beneficial effect of the present invention is that the piezoelectric transducer of the controlled object is simplified into a piezoelectric transducer transfer function, the LADRC controller parameters are simplified, and then the LADRC controller parameters are adjusted by the PSO optimization algorithm, so that the entire LADRC controller parameter adjustment process is automated and a lot of time is saved.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A piezoelectric transducer control method based on LADRC controller parameter adaptation, characterized in that: The method includes: An equivalent electrical model of the piezoelectric transducer is constructed, and a voltage excitation is input into the equivalent electrical model to obtain its voltage response and current response; Inputting the voltage response and the current response into a model identification toolbox respectively to obtain a piezoelectric transducer transfer function; Based on the transfer function of the piezoelectric transducer, the phase difference between the voltage signal and the current signal at the output end of its equivalent electrical model and the effective value of the current are calculated; The phase difference and the effective value of the current are input into the LADRC controller after parameter adjustment to generate a control signal, and the piezoelectric transducer is driven to operate in a resonant state through the control signal.

2. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1, characterized in that: The equivalent electrical model of the piezoelectric transducer is a parallel circuit constructed based on the Mason model. The parallel circuit is specifically: a first capacitor (C0) is connected in parallel with an RLC series circuit. The RLC series circuit is specifically: a second capacitor (C1), an inductor (L1) and a resistor (R1) are connected in series.

3. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1, characterized in that: The piezoelectric transducer transfer function includes a piezoelectric transducer gain transfer function and a piezoelectric transducer impedance transfer function.

4. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1, characterized in that: Based on the transfer function of the piezoelectric transducer, the phase difference between the voltage signal and the current signal at the output end of its equivalent electrical model is calculated. The specific calculation process includes: S301: sampling a voltage signal and a current signal at an output end of the equivalent electrical model to obtain a voltage or current discrete signal respectively; S302: intercepting N data of the voltage or current discrete signal, performing fast Fourier transform on the data, converting the data from the time domain to the frequency domain, and calculating the phase spectrum of the voltage or current discrete signal at the discrete frequency; S303: searching for index positions corresponding to the resonant frequencies in the phase spectrum of the voltage or current discrete signal respectively; S304: Calculate the phase difference between the voltage signal and the current signal by using the phase value of the corresponding index in the phase spectrum.

5. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1, characterized in that: The LADRC controller includes a linear extended state observer, a PD control combination and a compensation coefficient b0. The linear extended state observer includes three parameters, which are β 01 ,β 02 ,β 03 , where β 01 =3ω o , ω o represents the linear extended state observer bandwidth. The PD control combination includes two gain parameters, which are k p and k d , k p =2ω c , ω c Represents the gain factor.

6. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1, characterized in that: A control signal is generated by a LADRC controller, and the operation of the piezoelectric transducer is driven by the control signal, wherein the process includes a frequency controller and an amplitude controller.

7. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 6, characterized in that: The control process of the frequency controller includes: The calculated voltage signal, the phase difference between the current signal and the excitation voltage frequency are input into the linear extended state observer respectively to obtain the piezoelectric transducer state signal at the current moment; Comparing the piezoelectric transducer state signal with the target signal to obtain a phase difference error signal between the voltage signal and the current signal; The phase difference error signal is combined by PD control and a compensation coefficient b0 to obtain a frequency real-time control signal; The piezoelectric transducer is driven to operate in a resonant state by a frequency real-time control signal.

8. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 6, characterized in that: The control process of the frequency controller includes: The calculated effective current value and excitation voltage amplitude are input into the linear extended state observer respectively to obtain the piezoelectric transducer state signal at the current moment; Compare the state signal with the target signal to obtain a current effective value error signal; The current effective value error signal is combined through PD control and compensation coefficient b0 to obtain the amplitude real-time control signal; The piezoelectric transducer is driven to operate in a resonant state by a real-time amplitude control signal.

9. The piezoelectric transducer control method based on LADRC controller parameter adaptation according to claim 1 or 5, characterized in that: The LADRC controller parameters are adjusted by PSO optimization algorithm, and the specific process includes: Initialize the seed population, each particle represents a set of possible parameters (ω o ,ω c , b0), where ω o represents the bandwidth of the linear extended state observer in the LADRC controller, b0 represents the compensation coefficient of the LADRC controller, ω c Represents the gain coefficient, which determines the initial position and velocity of each particle. The position vector of each particle corresponds to the parameter value of the LADRC controller, and the velocity vector of each particle represents the direction and magnitude of the change of the parameter value; The fitness value of each particle is calculated according to the fitness function, and the fitness function is specifically: In the formula, J ITAE It represents the product of the absolute value of the error and the time integrated over time, t represents the time, and e(t) represents the error between the target signal and the output signal of the piezoelectric transducer at time t. Update the individual optimal solution of each particle and the global optimal solution of the entire particle swarm respectively; Iteratively update the speed and position of each particle until the iteration termination condition is reached, and output the parameter value of the LADRC controller corresponding to the historical optimal position of the group.

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