A method and system for tracking the resonant frequency of ultrasonic stone cutting

Abstract

This invention discloses a resonant frequency tracking control method and system for ultrasonic stone cutting, belonging to the field of stone cutting technology. It includes acquiring voltage and current signals from the output of an ultrasonic drive power supply; determining resonant state characterization parameters and load change characterization parameters based on the voltage and current signals; identifying the current cutting load state based on the load change characterization parameters, whereby the current cutting load state includes a stable load state, a slightly disturbed load state, and a sudden change load state; when the current cutting load state is a sudden change load state, establishing a local frequency seeking window centered on the current drive frequency, performing a local frequency sweep within the local frequency seeking window, determining the target resonant frequency based on the local frequency sweep results, and adjusting the drive frequency of the ultrasonic drive power supply to the target resonant frequency. This invention solves the problem of resonant frequency offset in ultrasonic vibration systems during stone cutting.

Description

Technical Field

[0001] This invention relates to the field of stone cutting technology, and in particular to a method and system for tracking and controlling the resonant frequency of ultrasonic stone cutting. Background Technology

[0002] In a typical ultrasonic stone cutting device, the ultrasonic drive power supply provides a high-frequency AC drive signal to the ultrasonic transducer. The ultrasonic transducer converts electrical energy into mechanical vibration, which is amplified by the amplitude transformer and transmitted to the cutting tool, causing the cutting tool to superimpose high-frequency micro-amplitude vibrations during stone cutting. To obtain high energy conversion efficiency and stable vibration output, the drive frequency of the ultrasonic drive power supply usually needs to be matched with the resonant frequency of the ultrasonic vibration system consisting of the ultrasonic transducer, amplitude transformer, and cutting tool.

[0003] However, the cutting load is not constant during stone cutting. The hardness, texture, internal inclusions, cutting depth, feed rate, and tool wear can all cause changes in the contact load between the tool and the stone. Especially when the tool enters areas of sudden hardness change, fissures, inclusions, or when the cutting contact area changes abruptly, the mechanical load on the ultrasonic vibration system will change abruptly, causing a shift in the resonant frequency. Furthermore, prolonged cutting can also cause temperature rise in the ultrasonic transducer, amplitude transformer, or cutting tool, further leading to a drift in the resonant frequency of the ultrasonic vibration system.

[0004] In existing technologies, common ultrasonic power supply resonant frequency tracking methods mainly include fixed frequency driving, initial frequency sweep to find resonance, phase closed-loop tracking based on voltage and current phase difference, and frequency tracking based on maximum current or minimum impedance. These methods can achieve certain results under relatively stable load conditions or with slow load changes.

[0005] However, for ultrasonic stone cutting and other high-disturbance load conditions, a single phase-closed-loop tracking method is easily affected by instantaneous cutting impacts, signal noise, and sudden load changes. When the cutting load experiences slight disturbances, adjusting the frequency solely based on the phase difference between voltage and current may not adequately reflect the changing trend of the stone cutting load, easily leading to frequency modulation response lag or local frequency jitter. When the cutting load undergoes sudden changes, continuing to use the original phase-closed-loop adjustment direction may cause the drive frequency to adjust away from the true resonant point, resulting in problems such as mistracking, frequency oscillation, or decreased vibration output.

[0006] Furthermore, traditional initial frequency sweep resonant search is typically used during equipment startup, and its search range is large and time-consuming, making it unsuitable for frequent execution during the cutting process. If a global frequency sweep is re-executed when the load changes abruptly, it may affect the continuity of the cutting process; if the frequency search is not re-executed, the ultrasonic drive frequency may not be able to relock a new resonant frequency in a timely manner.

[0007] Therefore, how to identify the current cutting load state based on the electrical signal output of the ultrasonic drive power supply during ultrasonic stone cutting, and how to adopt different resonant frequency tracking strategies for stable loads, slightly disturbed loads, and sudden change loads, in order to improve the resonant tracking stability of the ultrasonic vibration system under strong disturbance stone cutting conditions, has become a technical problem that needs to be solved. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a resonant frequency tracking control method and system for ultrasonic stone cutting, aiming to solve the problem of resonant frequency deviation in ultrasonic vibration systems during stone cutting in existing technologies.

[0009] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a resonant frequency tracking control method for ultrasonic stone cutting, including acquiring voltage and current signals at the output of an ultrasonic drive power supply. Based on the voltage signal and the current signal, determine the resonant state characterization parameters and the load change characterization parameters; The current cutting load state is identified based on the load change characterization parameters, and the current cutting load state includes a stable load state, a slight disturbance state, and a sudden change load state. When the current cutting load state is a sudden load state, a local frequency seeking window is established with the current driving frequency as the center. A local frequency sweep is performed within the local frequency seeking window, and the target resonant frequency is determined based on the local frequency sweep result. The driving frequency of the ultrasonic driving power supply is then adjusted to the target resonant frequency.

[0010] In some implementations, when the current cutting load state is a stable load state, the driving frequency of the ultrasonic driving power supply is adjusted in a phase closed loop according to the resonant state characterization parameter; when the current cutting load state is a slightly disturbed state, a joint error is constructed according to the resonant state characterization parameter and the load change characterization parameter, and the driving frequency of the ultrasonic driving power supply is adjusted according to the joint error.

[0011] In some embodiments, the resonant state characterization parameters include at least one of voltage-current phase difference, equivalent impedance, effective current value, and active power; the load change characterization parameters include at least one of phase difference change rate, equivalent impedance change rate, and effective current value change rate.

[0012] In some implementations, identifying the current cutting load state based on the load change characterization parameters includes: When the absolute value of the equivalent impedance change rate is less than the first impedance change rate threshold, and the absolute value of the current effective value change rate is less than the first current change rate threshold, the current load cutting state is identified as a stable load state. When the absolute value of the equivalent impedance change rate is greater than or equal to the first impedance change rate threshold and less than the second impedance change rate threshold, or when the absolute value of the current effective value change rate is greater than or equal to the first current change rate threshold and less than the second current change rate threshold, the current load cutting state is identified as a slight disturbance state. When the absolute value of the equivalent impedance change rate is greater than or equal to the second impedance change rate threshold, or the absolute value of the current effective value change rate is greater than or equal to the second current change rate threshold, or the absolute value of the phase difference change rate is greater than the phase change rate threshold, the current cut load state is identified as a sudden load state.

[0013] In some embodiments, when the current cutting load state is a stable load state, the driving frequency of the ultrasonic driving power supply is adjusted in a phase closed-loop manner according to the resonant state characterization parameters, including: The frequency adjustment direction and adjustment amount are determined based on the phase error between the voltage and current phase difference and the target phase. The driving frequency of the ultrasonic driving power supply is adjusted in a phase closed-loop manner according to the frequency adjustment direction and the frequency adjustment amount.

[0014] In some implementations, when the current cutting load state is a slightly disturbed state, a joint error is constructed based on the resonance state characterization parameters and the load change characterization parameters, including: The normalized phase error is obtained based on the phase error between the voltage and current phase difference and the target phase. Based on the change in equivalent impedance, the normalized change in impedance is obtained. The normalized phase error and the normalized impedance change are weighted and summed according to the preset phase weight and preset impedance weight to obtain the joint error. Adjusting the driving frequency of the ultrasonic driving power supply according to the joint error includes: determining the frequency adjustment step size according to the absolute value of the joint error, and adjusting the driving frequency of the ultrasonic driving power supply according to the frequency adjustment direction corresponding to the joint error and the frequency adjustment step size.

[0015] In some implementations, a local frequency sweep is performed within the local frequency search window, and the target resonant frequency is determined based on the local frequency sweep result, including: Within the local frequency search window, multiple candidate frequency points are determined according to the local frequency sweep step size; The ultrasonic drive power supply is controlled to sequentially output drive signals corresponding to each candidate frequency point; The voltage and current signals at the output of the ultrasonic drive power supply are collected at each candidate frequency point, and the voltage and current phase difference, equivalent impedance, effective current value and active power corresponding to each candidate frequency point are calculated. The comprehensive evaluation value of each candidate frequency point is calculated based on the voltage-current phase difference, equivalent impedance, effective current value, and active power corresponding to each candidate frequency point. The candidate frequency with the smallest comprehensive evaluation value is determined as the target resonant frequency.

[0016] In some implementations, the current cutting load state further includes an abnormal overload state, and the method further includes: When the effective value of the current is greater than the preset current threshold, or the active power is greater than the preset power threshold, the current load cutting state is identified as an abnormal overload state. When the current cutting load state is an abnormal overload state, overload protection control is executed; The overload protection control includes at least one of the following: reducing the output power of the ultrasonic drive power supply, reducing the cutting feed speed, maintaining a safe drive frequency, shutting off the output of the ultrasonic drive power supply, and issuing an alarm signal.

[0017] In some embodiments, before acquiring the voltage and current signals at the output of the ultrasonic drive power supply, the method further includes: The initial frequency search range is set according to the nominal resonant frequency of the ultrasonic transducer; The ultrasonic drive power supply is controlled to sweep the frequency within the initial frequency search range according to a preset frequency step size. The voltage and current signals at the output of the ultrasonic drive power supply are collected at each frequency sweep point, and the resonant state characterization parameters corresponding to each frequency sweep point are determined. The initial resonant frequency is determined based on the resonant state characterization parameters corresponding to each frequency sweep point, and the driving frequency of the ultrasonic driving power supply is adjusted to the initial resonant frequency.

[0018] Secondly, this application provides a resonant frequency tracking control system for ultrasonic stone cutting, comprising: The signal acquisition module is used to acquire the voltage and current signals at the output of the ultrasonic drive power supply. The parameter determination module is used to determine the resonance state characterization parameters and the load change characterization parameters based on the voltage signal and the current signal. The load status identification module is used to identify the current cutting load status based on the load change characterization parameters. The current cutting load status includes a stable load status, a slight disturbance status, and a sudden change load status. The mode-specific frequency modulation module is used to perform phase closed-loop adjustment of the driving frequency of the ultrasonic driving power supply according to the resonance state characterization parameter when the current cutting load state is a stable load state, and to construct a joint error according to the resonance state characterization parameter and the load change characterization parameter when the current cutting load state is a slight disturbance state, and to adjust the driving frequency of the ultrasonic driving power supply according to the joint error. The local frequency seeking module is used to establish a local frequency seeking window centered on the current driving frequency when the current cutting load state is a sudden load state, perform a local frequency sweep within the local frequency seeking window, determine the target resonant frequency based on the local frequency sweep result, and adjust the driving frequency of the ultrasonic driving power supply to the target resonant frequency.

[0019] The beneficial effects of this invention through the above technical solutions are as follows: Resonance state characterization parameters and load change characterization parameters are determined based on the voltage and current signals at the output of the ultrasonic drive power supply, and the current cutting load state is identified accordingly, enabling the drive frequency adjustment to match the load changes during stone cutting. Under stable load conditions, phase closed-loop adjustment is used, which helps maintain the continuity of frequency adjustment; under slight disturbance conditions, a joint error is constructed based on the resonance state characterization parameters and load change characterization parameters, which helps reduce the risk of mis-tuning caused by instantaneous disturbances in single phase adjustment; under sudden load conditions, local frequency seeking is performed with the current drive frequency as the center, which helps to recapture the target resonant frequency after a sudden load change, reducing the risk of frequency mistracking and oscillation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention, and the embodiments in the accompanying drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart of a resonant frequency tracking and control method for ultrasonic stone cutting provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an ultrasonic stone cutting device provided in an embodiment of this application; Figure 3 A flowchart for identifying the cutting load state is provided in one embodiment of this application; Figure 4 A schematic diagram of the driving frequency tracking process provided in an embodiment of this application; Figure 5 This is a flowchart of a local frequency seeking under a sudden load state provided in an embodiment of this application; Figure 6 This is a schematic diagram illustrating the correspondence between load change characterization parameters and load cutting state identification results provided in an embodiment of this application. Figure 7 A schematic diagram illustrating the frequency adjustment process under stable load and slight disturbance conditions according to an embodiment of this application; Figure 8 A schematic diagram of the overload protection control process under abnormal overload conditions provided in an embodiment of this application; Figure 9 A structural diagram of a resonant frequency tracking control system for ultrasonic stone cutting provided in an embodiment of this application; Figure 10 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.

[0022] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the application. Rather, these embodiments are provided to make the disclosure more thorough and complete, and to fully convey the scope of the disclosure to those skilled in the art.

[0024] The foregoing and other technical contents, features and effects of the present invention are described in conjunction with the appendix below. Figure 1-3 The detailed description of the embodiments will make this clear. All structural details mentioned in the following embodiments are based on the accompanying drawings.

[0025] This invention provides a resonant frequency tracking and control method and system for ultrasonic stone cutting, mainly applied to ultrasonic-assisted stone cutting equipment. The stone can be granite, marble, artificial stone, ceramic slabs, quartz slabs, or other hard and brittle materials. During the cutting process, these materials are prone to uneven hardness, local inclusions, cracks, changes in the cutting contact area, and tool wear, resulting in variations in the contact load between the tool and the stone over time. For ultrasonic-assisted cutting, these variations in cutting load affect the equivalent mechanical impedance and resonant frequency of the ultrasonic vibration system comprised of the ultrasonic transducer, amplitude transformer, and cutting tool. Therefore, during the cutting process, it is necessary to track and control the driving frequency of the ultrasonic drive power supply to keep it near the resonant frequency of the ultrasonic vibration system.

[0026] like Figure 2As shown, in one embodiment, the ultrasonic stone cutting device includes an ultrasonic drive power supply, an ultrasonic transducer, an amplitude transformer, a cutting tool, a voltage sampling circuit, a current sampling circuit, and a controller. The ultrasonic drive power supply outputs a high-frequency AC drive signal. The ultrasonic transducer is connected to the ultrasonic drive power supply and converts the high-frequency AC drive signal into mechanical vibration. The amplitude transformer is connected to the ultrasonic transducer and amplifies or transmits the mechanical vibration. The cutting tool is connected to the amplitude transformer and superimposes ultrasonic vibration during stone cutting. The voltage sampling circuit collects the voltage signal at the output of the ultrasonic drive power supply, and the current sampling circuit collects the current signal at the output of the ultrasonic drive power supply. The controller is connected to the voltage sampling circuit, the current sampling circuit, and the ultrasonic drive power supply, respectively, and determines the resonance state characterization parameters and load change characterization parameters based on the voltage and current signals, and adjusts the drive frequency of the ultrasonic drive power supply according to the current cutting load state.

[0027] An ultrasonic drive power supply may include a rectifier unit, an inverter unit, a frequency regulation unit, and a power control unit. The controller outputs drive frequency control commands to the frequency regulation unit, which adjusts the frequency of the high-frequency AC signal output by the inverter unit. A voltage sampling circuit can be located at the output terminal of the ultrasonic drive power supply or the input terminal of the ultrasonic transducer to acquire voltage signals reflecting the drive output state. A current sampling circuit can use a sampling resistor, current transformer, Hall effect current sensor, or other current detection element to acquire drive current signals. The controller can be a microcontroller, digital signal processor, programmable logic controller, industrial computer, or embedded control board.

[0028] like Figure 1 As shown, in one embodiment, the resonant frequency tracking control method includes the following steps.

[0029] S101, acquire the voltage and current signals at the output of the ultrasonic drive power supply.

[0030] Specifically, the controller acquires the voltage signal from the output terminal of the ultrasonic drive power supply through a voltage sampling circuit and the current signal from the output terminal of the ultrasonic drive power supply through a current sampling circuit. The voltage and current signals can be continuously sampled signals or discrete signals acquired according to a preset sampling period. The controller can perform filtering, noise reduction, amplitude normalization, or sampling synchronization processing on the acquired voltage and current signals to reduce the impact of sampling noise on subsequent parameter calculations.

[0031] S102, determine the resonant state characterization parameters and load change characterization parameters based on the voltage signal and the current signal.

[0032] In this embodiment, the resonance state characterization parameters are used to characterize the degree of deviation of the ultrasonic vibration system from the resonance state or the energy transfer state. The resonance state characterization parameters may include at least one of voltage-current phase difference, equivalent impedance, effective current value, and active power.

[0033] For example, the controller can determine the voltage-current phase difference based on the phase relationship between the voltage and current signals. This phase difference can be obtained through zero-crossing detection, phase-locked loops, quadrature demodulation, or discrete Fourier transform. The equivalent impedance can be determined based on the ratio of the effective voltage value to the effective current value; active power can be determined based on the effective voltage value, the effective current value, and the voltage-current phase difference.

[0034] Load variation characterization parameters are used to characterize the degree of change in cutting load during stone cutting. These parameters may include at least one of the following: phase difference change rate, equivalent impedance change rate, and current RMS value change rate. Specifically, the controller can calculate the phase difference change rate, equivalent impedance change rate, and current RMS value change rate based on the voltage-current phase difference, equivalent impedance, and current RMS value within adjacent sampling periods or multiple consecutive sampling periods.

[0035] S103, Identify the current cutting load state based on the load change characterization parameters.

[0036] like Figure 3 As shown, the current load state can include a stable load state, a slightly disturbed load state, and a sudden load state. In some embodiments, the current load state can also include an abnormal overload state.

[0037] In a specific example, when the absolute value of the equivalent impedance change rate is less than the first impedance change rate threshold, and the absolute value of the current effective value change rate is less than the first current change rate threshold, the current cutting load state is identified as a stable load state. This state indicates that the contact load between the tool and the stone changes little, and the resonance state of the ultrasonic vibration system changes relatively smoothly.

[0038] When the absolute value of the equivalent impedance change rate is greater than or equal to the first impedance change rate threshold and less than the second impedance change rate threshold, or when the absolute value of the effective current change rate is greater than or equal to the first current change rate threshold and less than the second current change rate threshold, the current cutting load state is identified as a slight disturbance state. This state indicates that the cutting load has changed to some extent, but has not yet reached a sudden change level.

[0039] When the absolute value of the equivalent impedance change rate is greater than or equal to the second impedance change rate threshold, or the absolute value of the current effective value change rate is greater than or equal to the second current change rate threshold, or the absolute value of the phase difference change rate is greater than the phase change rate threshold, the current cutting load state is identified as a sudden load state. This state may correspond to the working condition where the tool enters a region of sudden change in stone hardness, an inclusion region, a crack region, or a sudden change in the cutting contact area.

[0040] The aforementioned first impedance change rate threshold, second impedance change rate threshold, first current change rate threshold, second current change rate threshold, and phase change rate threshold can be preset based on equipment calibration results, stone type, cutting depth, tool specifications, or historical cutting data. To avoid frequent state switching, multiple consecutive sampling cycle confirmation conditions can be set, or different hysteresis judgment methods can be set for entry and exit thresholds.

[0041] For clarity on the above-described mode-specific frequency modulation process, please refer to [link / reference]. Figure 4 In an illustrative control process, the rate of change of equivalent impedance, the rate of change of effective current value, and the rate of change of phase difference change with the cutting time. The controller outputs the current cutting load status based on the relationship between each rate of change and the corresponding threshold. Figure 4 The status numbers in the diagram are only used to indicate the status identification results. The stable load status, slight disturbance status, sudden load status, and abnormal overload status correspond to different control processing methods. Figure 4 It is not used to specify the exact value of each threshold.

[0042] S104, when the current cutting load state is a stable load state, the driving frequency of the ultrasonic drive power supply is adjusted in phase closed loop according to the resonant state characterization parameters.

[0043] Specifically, the controller can determine the frequency adjustment direction and amount based on the phase error between the voltage-current phase difference and the target phase, and adjust the driving frequency of the ultrasonic drive power supply according to the frequency adjustment direction and amount. The target phase can be zero phase or a target phase range set according to the characteristics of the ultrasonic vibration system.

[0044] For example, when the voltage-current phase difference is greater than the target phase, the controller can adjust the drive frequency along a first direction; when the voltage-current phase difference is less than the target phase, the controller can adjust the drive frequency along a second direction. The frequency adjustment amount can be determined based on the magnitude of the phase error, or it can be determined through proportional control, proportional-integral control, or table lookup. Using phase closed-loop control under stable load conditions can maintain the continuity of drive frequency adjustment when load changes are small.

[0045] S105, when the current cutting load state is a slight disturbance state, construct a joint error based on the resonance state characterization parameter and the load change characterization parameter, and adjust the driving frequency of the ultrasonic drive power supply based on the joint error.

[0046] Specifically, the controller can obtain the normalized phase error based on the phase error between the voltage and current phase difference and the target phase, and obtain the normalized impedance change based on the change in equivalent impedance. Subsequently, the controller performs a weighted summation of the normalized phase error and the normalized impedance change according to preset phase weights and preset impedance weights to obtain the joint error.

[0047] For example, the joint error can be expressed as: E = α·Ep + β·Ez; where E represents the joint error, Ep represents the normalized phase error, Ez represents the normalized impedance change, α represents the preset phase weight, and β represents the preset impedance weight. The preset phase weight and preset impedance weight can be set according to the equipment calibration results or the stone cutting conditions.

[0048] After obtaining the joint error, the controller can determine the frequency adjustment step size based on the absolute value of the joint error, and adjust the driving frequency of the ultrasonic drive power supply according to the frequency adjustment direction and step size corresponding to the joint error. For example, when the absolute value of the joint error is small, a smaller frequency adjustment step size is used; when the absolute value of the joint error is large, a larger frequency adjustment step size is used. In this way, under slight disturbance conditions, the drive frequency adjustment not only considers the resonant phase deviation but also the load change trend, which helps to reduce the risk of mis-tuning under disturbance conditions by single-phase closed-loop regulation.

[0049] S106, when the current cutting load state is a sudden load state, a local frequency seeking window is established with the current driving frequency as the center, a local frequency sweep is performed within the local frequency seeking window, and the target resonant frequency is determined based on the local frequency sweep result, and the driving frequency of the ultrasonic driving power supply is adjusted to the target resonant frequency.

[0050] like Figure 5 As shown, under sudden load conditions, the controller does not continue frequency adjustment along the original phase closed-loop direction, but instead establishes a local frequency seeking window centered on the current driving frequency. The local frequency seeking window can be represented as: [fn-Δf, fn+Δf] Where fn represents the current driving frequency, and Δf represents the local frequency seeker half-width. Δf can be a preset value, or it can be determined based on the rate of change of equivalent impedance, the rate of change of effective current value, or the rate of change of phase difference.

[0051] Within the local frequency search window, the controller determines multiple candidate frequency points according to the local frequency sweep step size, and controls the ultrasonic drive power supply to sequentially output the drive signal corresponding to each candidate frequency point. For each candidate frequency point, the controller acquires the voltage and current signals at the output terminal of the ultrasonic drive power supply at that candidate frequency point, and calculates the corresponding voltage and current phase difference, equivalent impedance, current RMS value, and active power.

[0052] Subsequently, the controller calculates a comprehensive evaluation value based on the voltage-current phase difference, equivalent impedance, RMS current value, and active power corresponding to each candidate frequency point. This comprehensive evaluation value can be used to assess how close the candidate frequency point is to the resonant state. In one example, the comprehensive evaluation value can be determined by weighting the absolute value of the voltage-current phase difference, equivalent impedance, RMS current value, and active power. The controller can then determine the candidate frequency point with the smallest comprehensive evaluation value as the target resonant frequency.

[0053] After determining the target resonant frequency, the controller adjusts the driving frequency of the ultrasonic drive power supply to the target resonant frequency. In some implementations, to reduce frequency abrupt changes, a smooth switching method can be used to gradually adjust the current driving frequency to the target resonant frequency. For example, the frequency can be updated as follows: fn+1 = fn + γ·(ft - fn) Where fn+1 represents the driving frequency of the next sampling period, fn represents the current driving frequency, ft represents the target resonant frequency, γ represents the frequency smoothing coefficient, and 0 < γ ≤ 1.

[0054] Using a local frequency-seeking method under sudden load conditions can recapture the resonant point around the current operating frequency. Compared with re-performing a global frequency sweep, it can shorten the impact of the frequency-seeking process on the continuity of the cut. Compared with continuing to perform the original phase closed-loop adjustment, it can reduce the risk of mistracking caused by sudden load changes.

[0055] For clarity on the above-described mode-specific frequency modulation process, please refer to [link / reference]. Figure 6 , Figure 6 The diagram illustrates the process of drive frequency variation over time under different load conditions. Under stable load conditions, the drive frequency is slightly adjusted around the target resonant frequency; under slight disturbance conditions, the drive frequency is gradually corrected based on the joint error; under sudden load conditions, the controller performs local frequency seeking centered on the current drive frequency and adjusts the drive frequency to the newly determined target resonant frequency. Figure 6 The curves in the diagram are used to illustrate the tracking process of the driving frequency, without specifying a particular frequency value.

[0056] In one specific embodiment, the controller determines the resonant state characterization parameters and load change characterization parameters based on the acquired voltage and current signals. The resonant state characterization parameters reflect the degree of deviation of the ultrasonic vibration system from its resonant state or its energy transfer state, and may include at least one of voltage-current phase difference, equivalent impedance, effective current value, and active power.

[0057] Specifically, the controller can calculate the effective values ​​of the voltage signal and the current signal in each sampling period, and determine the equivalent impedance based on the ratio of the effective voltage value to the effective current value. Let the effective voltage value in the nth sampling period be Urms(n) and the effective current value be Irms(n), then the equivalent impedance Z(n) can be expressed as: Z(n) = Urms(n) / Irms(n).

[0058] The voltage-current phase difference can be determined through zero-crossing detection, phase-locked loop, quadrature demodulation, or discrete Fourier transform. Let the voltage-current phase difference in the nth sampling period be φ(n), then the active power P(n) can be determined based on the RMS voltage, RMS current, and voltage-current phase difference, for example: P(n)=Urms(n)·Irms(n)·cosφ(n).

[0059] In other implementations, active power can also be obtained by averaging the product of instantaneous voltage and instantaneous current over one or more drive cycles.

[0060] Load variation characterization parameters reflect the degree of change in the contact load between the tool and the stone during stone cutting, and may include at least one of the following: phase difference change rate, equivalent impedance change rate, and current RMS value change rate. The controller can calculate the corresponding change rates based on the voltage-current phase difference, equivalent impedance, and current RMS value within adjacent sampling periods. For example, with a sampling period of Ts, the phase difference change rate dφ(n), equivalent impedance change rate dZ(n), and current RMS value change rate dI(n) can be expressed as follows: dφ(n)=[φ(n)-φ(n-1)] / Ts; dZ(n) = [Z(n) - Z(n-1)] / Ts; dI(n)=[Irms(n)-Irms(n-1)] / Ts.

[0061] To reduce the impact of instantaneous sampling noise on state judgment, the controller can also calculate the aforementioned rate of change based on a sliding window of multiple consecutive sampling periods. For example, within a sliding window of length M, a linear fit is performed on the voltage-current phase difference, equivalent impedance, or effective current value, and the fitting slope is used as the corresponding rate of change.

[0062] In one specific embodiment, the controller identifies the current cutting load state based on load change characterization parameters. The current cutting load state includes a stable load state, a slightly disturbed state, and a sudden load state. A stable load state corresponds to a condition where the contact load between the tool and the stone changes little and the ultrasonic vibration system operates relatively smoothly; a slightly disturbed state corresponds to a condition where the stone's hardness, texture, or cutting contact state changes to some extent but has not yet reached a sudden change; a sudden load state corresponds to a condition where the tool enters a region of sudden hardness change, an inclusion region, a crack region, or where the cutting contact area suddenly changes.

[0063] Specifically, when the absolute value of the equivalent impedance change rate is less than the first impedance change rate threshold, and the absolute value of the current effective value change rate is less than the first current change rate threshold, the controller identifies the current cutting load state as a stable load state. This judgment indicates that the electrical equivalent load change of the ultrasonic vibration system is small, making it suitable for fine-tuning the drive frequency using a phase closed-loop method with good continuity.

[0064] When the absolute value of the equivalent impedance change rate is greater than or equal to the first impedance change rate threshold and less than the second impedance change rate threshold, or when the absolute value of the effective current change rate is greater than or equal to the first current change rate threshold and less than the second current change rate threshold, the controller identifies the current cutting load state as a slight disturbance. This judgment indicates that the cutting load has changed, but is still within the range that can be tracked through closed-loop adjustment.

[0065] When the absolute value of the equivalent impedance change rate is greater than or equal to the second impedance change rate threshold, or the absolute value of the current effective value change rate is greater than or equal to the second current change rate threshold, or the absolute value of the phase difference change rate is greater than the phase change rate threshold, the controller identifies the current load cutting state as a sudden load change state. This judgment indicates that the load cutting is changing drastically, and the original phase closed-loop adjustment direction may no longer be reliable, requiring a re-determination of the target resonant frequency through local frequency seeking.

[0066] The first impedance change rate threshold is less than the second impedance change rate threshold, and the first current change rate threshold is less than the second current change rate threshold. Each threshold can be determined through no-load calibration, light-load calibration, different stone cutting experiments, or historical operating data of the ultrasonic stone cutting equipment. To avoid frequent switching of load states near the thresholds, the controller can also set confirmation conditions for multiple consecutive sampling cycles, or set hysteresis judgment conditions with different entry and exit thresholds.

[0067] In one specific embodiment, when the current cutting load state is a stable load state, the controller performs phase closed-loop adjustment of the driving frequency of the ultrasonic drive power supply according to the resonant state characterization parameters. Specifically, the controller determines the frequency adjustment direction and frequency adjustment amount based on the phase error between the voltage-current phase difference and the target phase.

[0068] Let the target phase be φref, and the phase difference between voltage and current in the nth sampling period be φ(n). Then the phase error eφ(n) can be expressed as: eφ(n) = φ(n) - φref.

[0069] The target phase can be zero phase, or a target phase value or target phase range determined based on the calibration results of the ultrasonic vibration system consisting of the ultrasonic transducer, amplitude transformer, and cutting tool. When the absolute value of the phase error is less than the preset phase dead zone threshold, the controller can maintain the current driving frequency unchanged to reduce frequency jitter near the resonant point. When the absolute value of the phase error is greater than or equal to the preset phase dead zone threshold, the controller determines the frequency adjustment direction based on the sign of the phase error and the frequency adjustment amount based on the absolute value of the phase error.

[0070] For example, the frequency adjustment amount Δfφ(n) can be determined according to the proportional relationship: Δfφ(n) = np·eφ(n), where np is the phase adjustment coefficient. The controller updates the driving frequency of the ultrasonic drive power supply according to the frequency adjustment direction and the frequency adjustment amount. In practical applications, the direction of frequency increase or decrease can be pre-calibrated according to the frequency-phase characteristics of the ultrasonic vibration system.

[0071] In one specific embodiment, when the current cutting load state is under slight disturbance, the controller constructs a joint error based on the resonant state characterization parameters and the load change characterization parameters, and adjusts the driving frequency of the ultrasonic drive power supply according to the joint error. This control method is used to simultaneously consider the resonant phase deviation and the load change trend when the cutting load undergoes slight changes, reducing the risk of being affected by transient disturbances when adjusting solely based on the voltage and current phase difference.

[0072] Specifically, the controller obtains the normalized phase error based on the phase error between the voltage and current phase difference and the target phase. Let the phase error be eφ(n), and the preset phase normalization reference be φmax, then the normalized phase error Ep(n) can be expressed as: Ep(n) = eφ(n) / φmax.

[0073] The controller obtains the normalized impedance change based on the change in equivalent impedance. Let the equivalent impedance of the current sampling period be Z(n), the equivalent impedance of the previous sampling period be Z(n-1), and the reference impedance be Zref. Then the normalized impedance change Ez(n) can be expressed as: Ez(n) = [Z(n) - Z(n-1)] / Zref. Here, Zref can be the unloaded resonant impedance, the initial resonant impedance, or the average value of the equivalent impedance within a preset time window.

[0074] Subsequently, the controller performs a weighted summation of the normalized phase error and the normalized impedance change according to preset phase weights and preset impedance weights, obtaining the joint error E(n): E(n) = α·Ep(n) + β·Ez(n), where α is the preset phase weight and β is the preset impedance weight. The preset phase weight and preset impedance weight can be determined through experimental calibration or dynamically adjusted according to the degree of load change. For example, when the equivalent impedance change rate is small, the phase weight can be increased; when the equivalent impedance change rate increases but has not yet reached the sudden load judgment threshold, the impedance weight can be increased.

[0075] The controller determines the frequency adjustment step size based on the absolute value of the combined error and adjusts the driving frequency of the ultrasonic drive power supply according to the frequency adjustment direction and step size corresponding to the combined error. For example, when the absolute value of the combined error is less than a first error threshold, a first frequency adjustment step size is used; when the absolute value of the combined error is greater than or equal to the first error threshold and less than a second error threshold, a second frequency adjustment step size is used; and when the absolute value of the combined error is greater than or equal to the second error threshold, a third frequency adjustment step size is used. The first frequency adjustment step size is smaller than the second frequency adjustment step size, and the second frequency adjustment step size is smaller than the third frequency adjustment step size. Therefore, under slight disturbance conditions, the driving frequency can be adjusted to different magnitudes according to the degree of disturbance.

[0076] See Figure 7 Under stable load conditions, the frequency adjustment mainly changes slightly with the phase error; under slight disturbance conditions, the combined error introduces both the phase error term and the impedance change term, enabling the frequency adjustment to be adjusted according to the degree of load disturbance. Figure 7 This is used to illustrate the control differences between phase closed-loop regulation and joint error regulation, without specifying the exact value of the regulation amount.

[0077] In one specific embodiment, when the current load state is a sudden change in load condition, the controller performs a local frequency sweep within a local frequency seeking window and determines the target resonant frequency based on the local frequency sweep result. Specifically, the controller establishes a local frequency seeking window centered on the current driving frequency fn. The local frequency seeking window can be represented as: [fn-Δfl, fn+Δfl], where Δfl is the half-width of the local frequency seeking window. The half-width of the local frequency seeking window can be a preset value or determined based on the rate of change of equivalent impedance, the rate of change of effective current value, or the rate of change of phase difference. The greater the degree of load change, the larger the half-width of the local frequency seeking window can be set; when the degree of load change is small, the half-width of the local frequency seeking window can be set smaller to shorten the frequency seeking time.

[0078] Within a local frequency search window, the controller determines multiple candidate frequency points according to a local frequency sweep step size, and controls the ultrasonic drive power supply to sequentially output drive signals corresponding to each candidate frequency point. For each candidate frequency point, the controller acquires the voltage and current signals at the output terminal of the ultrasonic drive power supply at that candidate frequency point, and calculates the corresponding voltage-current phase difference, equivalent impedance, effective current value, and active power.

[0079] Subsequently, the controller calculates the comprehensive evaluation value for each candidate frequency point based on the voltage-current phase difference, equivalent impedance, effective current value, and active power corresponding to each candidate frequency point. The comprehensive evaluation value characterizes the degree to which a candidate frequency point approaches a resonant state. In one example, the comprehensive evaluation value Q(f) can be expressed as: Q(f) = λ1·|φ(f)| / φmax + λ2·Z(f) / Zref - λ3·P(f) / Pref, where φ(f) represents the voltage-current phase difference corresponding to candidate frequency f, Z(f) represents the equivalent impedance corresponding to candidate frequency f, P(f) represents the active power corresponding to candidate frequency f, φmax, Zref, and Pref are the normalization references for phase, impedance, and power, respectively, and λ1, λ2, and λ3 are the corresponding weights. The above comprehensive evaluation value is only an example; in other embodiments, the effective value of current can also be included in the comprehensive evaluation value.

[0080] The controller determines the candidate frequency with the lowest overall evaluation value as the target resonant frequency. After determining the target resonant frequency, the controller adjusts the drive frequency of the ultrasonic drive power supply to the target resonant frequency. See also... Figure 8 Under sudden load conditions, the controller establishes a local frequency-seeking window centered on the current driving frequency fn, and forms multiple candidate frequency points within this window. For each candidate frequency point, the controller calculates the corresponding comprehensive evaluation value Q(f), and determines the candidate frequency point with the smallest comprehensive evaluation value as the target resonant frequency ft. Thus, the local frequency-seeking process revolves around the current operating frequency, rather than re-performing a global frequency search.

[0081] In some implementations, to reduce the impact of frequency abrupt changes on the cutting process, the controller can use a smooth switching method to gradually adjust the current driving frequency to the target resonant frequency. For example: fn+1=fn+γ·(ft-fn), where fn+1 is the driving frequency of the next sampling period, fn is the current driving frequency, ft is the target resonant frequency, and γ is the frequency smoothing coefficient, 0<γ≤1.

[0082] In one specific embodiment, the current cutting load state also includes an abnormal overload state. When the effective value of the current exceeds a preset current threshold, or the active power exceeds a preset power threshold, the controller identifies the current cutting load state as an abnormal overload state. An abnormal overload state typically indicates that the contact resistance between the tool and the stone is too high, or that the ultrasonic vibration system is in an unfavorable operating condition. At this time, the controller executes overload protection control.

[0083] Overload protection control includes at least one of the following: reducing the output power of the ultrasonic drive power supply, reducing the cutting feed speed, maintaining a safe drive frequency, shutting off the output of the ultrasonic drive power supply, and issuing an alarm signal. Specifically, when the effective current value exceeds a preset current threshold but the shutdown protection condition is not met, the controller can reduce the output power of the ultrasonic drive power supply and limit the drive frequency adjustment range; when the effective current value continuously exceeds the preset current threshold or the active power continuously exceeds the preset power threshold, the controller can shut off the output of the ultrasonic drive power supply and issue an alarm signal. In the case where the ultrasonic stone cutting equipment includes a feed mechanism, the controller can also output a deceleration command to the feed mechanism to reduce the contact load between the tool and the stone.

[0084] See Figure 8 When the effective value of the current exceeds the preset current threshold or the active power exceeds the preset power threshold, the controller identifies it as an abnormal overload state and triggers overload protection control. Figure 8 The diagram illustrates the changes in the RMS current, output power, and cutting feed speed before and after overload triggering. The decrease in output power and cutting feed speed is used to represent the power reduction and feed reduction protection actions, without specifying the exact magnitude of the decrease.

[0085] In one specific embodiment, before acquiring the voltage and current signals at the output of the ultrasonic drive power supply, the controller also performs an initial frequency search process. Specifically, the controller sets an initial frequency search interval based on the nominal resonant frequency of the ultrasonic transducer. Let the nominal resonant frequency of the ultrasonic transducer be f0, then the initial frequency search interval can be set as: [f0-Δfs, f0+Δfs], where Δfs is half the width of the initial frequency search interval.

[0086] The controller controls the ultrasonic drive power supply to sweep frequencies within an initial frequency search interval according to a preset frequency step size. At each sweep frequency point, the controller acquires the voltage and current signals from the output terminal of the ultrasonic drive power supply and determines the resonant state characterization parameters corresponding to each sweep frequency point. The resonant state characterization parameters may include at least one of the following: voltage-current phase difference, equivalent impedance, effective current value, and active power. The controller can calculate the corresponding initial frequency seeking evaluation value based on the resonant state characterization parameters for each sweep frequency point, and determine the sweep frequency point whose initial frequency seeking evaluation value meets preset conditions as the initial resonant frequency. For example, the sweep frequency point with the smallest initial frequency seeking evaluation value can be determined as the initial resonant frequency, or the sweep frequency point with the smallest absolute value of the voltage-current phase difference and whose active power meets preset conditions can be determined as the initial resonant frequency. After determining the initial resonant frequency, the controller adjusts the drive frequency of the ultrasonic drive power supply to the initial resonant frequency and enters the subsequent real-time resonant frequency tracking control process.

[0087] Based on the same inventive concept, this application also provides a method. The solution provided by this method is similar to the solution described in the above system. Therefore, the specific limitations in one or more method embodiments provided below can be found in the limitations described above, and will not be repeated here.

[0088] In one exemplary embodiment, such as Figure 9 As shown, this embodiment also provides a resonant frequency tracking control system for ultrasonic stone cutting. The system includes a signal acquisition module, a parameter determination module, a load state identification module, a mode-specific frequency modulation module, and a local frequency seeking module.

[0089] The signal acquisition module acquires the voltage and current signals from the output of the ultrasonic drive power supply. The parameter determination module determines the resonant state characterization parameters and load change characterization parameters based on the voltage and current signals. The load state identification module identifies the current cutting load state based on the load change characterization parameters. The current cutting load state includes a stable load state, a slightly disturbed state, and a sudden change in load state.

[0090] The mode-specific frequency modulation module is used to perform phase closed-loop adjustment of the ultrasonic drive power supply's driving frequency based on the resonance state characterization parameters when the current cutting load state is a stable load state; and when the current cutting load state is a slightly disturbed state, it constructs a joint error based on the resonance state characterization parameters and load change characterization parameters, and adjusts the ultrasonic drive power supply's driving frequency based on the joint error. The local frequency seeking module is used to establish a local frequency seeking window centered on the current driving frequency when the current cutting load state is a sudden load state, performs a local frequency sweep within the local frequency seeking window, determines the target resonance frequency based on the local frequency sweep results, and adjusts the ultrasonic drive power supply's driving frequency to the target resonance frequency.

[0091] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 10 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and databases. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media to run. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection.

[0092] Those skilled in the art will understand that Figure 10 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0093] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0094] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0095] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0096] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (Read-Only Memory). Memory includes ROM, magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0097] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method of resonant frequency tracking control for ultrasonic stone cutting, characterized by, The method includes: Acquire the voltage and current signals at the output of the ultrasonic drive power supply; Based on the voltage signal and the current signal, determine the resonant state characterization parameters and the load change characterization parameters; The current cutting load state is identified based on the load change characterization parameters, and the current cutting load state includes a stable load state, a slight disturbance state, and a sudden change load state. When the current cutting load state is a sudden load state, a local frequency seeking window is established with the current driving frequency as the center. A local frequency sweep is performed within the local frequency seeking window, and the target resonant frequency is determined based on the local frequency sweep result. The driving frequency of the ultrasonic driving power supply is then adjusted to the target resonant frequency.

2. The method of claim 1, wherein, The method further includes: When the current cutting load state is a stable load state, the driving frequency of the ultrasonic driving power supply is adjusted in phase closed loop according to the resonance state characterization parameters. When the current cutting load state is in a slightly disturbed state, a joint error is constructed based on the resonance state characterization parameter and the load change characterization parameter, and the driving frequency of the ultrasonic driving power supply is adjusted based on the joint error.

3. The method of claim 2, wherein, The resonant state characterization parameters include at least one of voltage-current phase difference, equivalent impedance, effective current value, and active power. The load change characterization parameters include at least one of the phase difference change rate, equivalent impedance change rate, and current effective value change rate.

4. The method of claim 3, wherein, Identifying the current cutting load state based on the load change characterization parameters includes: When the absolute value of the equivalent impedance change rate is less than the first impedance change rate threshold, and the absolute value of the current effective value change rate is less than the first current change rate threshold, the current load cutting state is identified as a stable load state. When the absolute value of the equivalent impedance change rate is greater than or equal to the first impedance change rate threshold and less than the second impedance change rate threshold, or when the absolute value of the current effective value change rate is greater than or equal to the first current change rate threshold and less than the second current change rate threshold, the current load cutting state is identified as a slight disturbance state. When the absolute value of the equivalent impedance change rate is greater than or equal to the second impedance change rate threshold, or the absolute value of the current effective value change rate is greater than or equal to the second current change rate threshold, or the absolute value of the phase difference change rate is greater than the phase change rate threshold, the current cut load state is identified as a sudden load state.

5. The method of claim 2, wherein, When the current cutting load state is a stable load state, the driving frequency of the ultrasonic driving power supply is adjusted in a phase closed loop according to the resonant state characterization parameters, including: The frequency adjustment direction and adjustment amount are determined based on the phase error between the voltage and current phase difference and the target phase. The driving frequency of the ultrasonic driving power supply is adjusted in a phase closed-loop manner according to the frequency adjustment direction and the frequency adjustment amount.

6. The method of claim 2, wherein, When the current cutting load state is a slightly disturbed state, a joint error is constructed based on the resonance state characterization parameter and the load change characterization parameter, including: The normalized phase error is obtained based on the phase error between the voltage and current phase difference and the target phase. Based on the change in equivalent impedance, the normalized change in impedance is obtained. The normalized phase error and the normalized impedance change are weighted and summed according to the preset phase weight and preset impedance weight to obtain the joint error. Adjusting the driving frequency of the ultrasonic driving power supply according to the joint error includes: determining the frequency adjustment step size according to the absolute value of the joint error, and adjusting the driving frequency of the ultrasonic driving power supply according to the frequency adjustment direction corresponding to the joint error and the frequency adjustment step size.

7. The method of claim 2, wherein, Performing a local frequency sweep within the local frequency search window and determining the target resonant frequency based on the local frequency sweep results includes: Within the local frequency search window, multiple candidate frequency points are determined according to the local frequency sweep step size; The ultrasonic drive power supply is controlled to sequentially output drive signals corresponding to each candidate frequency point; The voltage and current signals at the output of the ultrasonic drive power supply are collected at each candidate frequency point, and the voltage and current phase difference, equivalent impedance, effective current value and active power corresponding to each candidate frequency point are calculated. The comprehensive evaluation value of each candidate frequency point is calculated based on the voltage-current phase difference, equivalent impedance, effective current value, and active power corresponding to each candidate frequency point. The candidate frequency with the smallest comprehensive evaluation value is determined as the target resonant frequency.

8. The method according to any one of claims 1 to 7, characterized in that, The current cutting load state also includes an abnormal overload state, and the method further includes: When the effective value of the current is greater than the preset current threshold, or the active power is greater than the preset power threshold, the current load cutting state is identified as an abnormal overload state. When the current cutting load state is an abnormal overload state, overload protection control is executed; The overload protection control includes at least one of the following: reducing the output power of the ultrasonic drive power supply, reducing the cutting feed speed, maintaining a safe drive frequency, shutting off the output of the ultrasonic drive power supply, and issuing an alarm signal.

9. The method according to any one of claims 1 to 7, characterized in that, Before acquiring the voltage and current signals at the output of the ultrasonic drive power supply, the method further includes: The initial frequency search range is set according to the nominal resonant frequency of the ultrasonic transducer; The ultrasonic drive power supply is controlled to sweep the frequency within the initial frequency search range according to a preset frequency step size. The voltage and current signals at the output of the ultrasonic drive power supply are collected at each frequency sweep point, and the resonant state characterization parameters corresponding to each frequency sweep point are determined. The initial resonant frequency is determined based on the resonant state characterization parameters corresponding to each frequency sweep point, and the driving frequency of the ultrasonic driving power supply is adjusted to the initial resonant frequency.

10. A resonant frequency tracking control system for ultrasonic stone cutting, characterized in that, include: The signal acquisition module is used to acquire the voltage and current signals at the output of the ultrasonic drive power supply. The parameter determination module is used to determine the resonance state characterization parameters and the load change characterization parameters based on the voltage signal and the current signal. The load status identification module is used to identify the current cutting load status based on the load change characterization parameters. The current cutting load status includes a stable load status, a slight disturbance status, and a sudden change load status. The mode-specific frequency modulation module is used to perform phase closed-loop adjustment of the driving frequency of the ultrasonic driving power supply according to the resonance state characterization parameter when the current cutting load state is a stable load state, and to construct a joint error according to the resonance state characterization parameter and the load change characterization parameter when the current cutting load state is a slight disturbance state, and to adjust the driving frequency of the ultrasonic driving power supply according to the joint error. The local frequency seeking module is used to establish a local frequency seeking window centered on the current driving frequency when the current cutting load state is a sudden load state, perform a local frequency sweep within the local frequency seeking window, determine the target resonant frequency based on the local frequency sweep result, and adjust the driving frequency of the ultrasonic driving power supply to the target resonant frequency.

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