CN-121821240-B - Piezoelectric crystal grinding control system based on frequency test technology

Abstract

The invention discloses a piezoelectric crystal grinding control system based on a frequency test technology. The dynamic mapping control module is internally provided with a dynamic mapping model, takes the accurate resonance frequency, the change rate and the vibration intensity as input, outputs the rotating speed, the pressure and the feeding quantity of the grinding head, dynamically corrects and pre-judges the output by the vibration working condition correction unit and the frequency drift pre-judging unit to generate a grinding parameter instruction, the execution driving module drives the grinding head to adjust the working parameter according to the instruction, and the closed-loop self-calibration module corrects the compensation coefficient and the model weight according to the actual frequency convergence effect. The invention realizes the full-link closed-loop precise control of the grinding process, effectively inhibits vibration interference and improves the frequency test precision and the processing consistency.

Inventors

• YANG JIANCHUN
• ZHANG FURU
• LI YUANSHENG
• HUANG KEJIA
• HUANG HANGUANG

Assignees

• 宁波翌波光电科技有限公司

Dates

Publication Date

20260508

Application Date

20260313

Claims (10)

1. 1. A piezoelectric crystal lapping control system based on frequency testing techniques, comprising: The hardware acquisition module acquires original resonance frequency signals, vibration intensity and grinding head working parameters; The frequency test compensation module is connected with the hardware acquisition module and comprises: the signal separation unit is used for receiving the original resonance frequency signal and the vibration intensity and outputting a crystal resonance signal and a vibration interference signal; The accurate frequency calculation unit is connected with the signal separation unit and a preset compensation coefficient library and is used for calculating accurate resonance frequency and accurate frequency change rate according to the crystal resonance signal, the vibration interference signal and the compensation coefficient corresponding to the vibration intensity; The dynamic mapping control module is connected with the frequency test compensation module and the hardware acquisition module and comprises: The dynamic mapping model is used for receiving the accurate resonance frequency, the accurate frequency change rate and the vibration intensity and outputting the rotating speed, the pressure and the feeding quantity of the grinding head; the vibration working condition correction unit is connected with the dynamic mapping model and is used for correcting model output when the vibration intensity exceeds a threshold value; The frequency drift advanced pre-judging unit is connected with the vibration working condition correcting unit and is used for pre-judging the frequency drift amount according to the vibration intensity and advanced correcting the output of the frequency drift amount to generate a grinding parameter instruction; The execution driving module is connected with the dynamic mapping control module and used for driving the grinding head to adjust working parameters according to the grinding parameter instruction; The closed loop self-calibration module is connected with the frequency test compensation module and the dynamic mapping control module and comprises: the effect acquisition unit is used for acquiring the actual frequency convergence effect of the grinded crystal; the compensation coefficient correction unit is connected with the effect acquisition unit and the compensation coefficient library and is used for correcting the compensation coefficient according to the actual frequency convergence effect; and the model weight optimizing unit is connected with the effect acquisition unit and the dynamic mapping model and is used for converging the effect optimizing model weight according to the actual frequency.
2. 2. The piezoelectric crystal grinding control system based on frequency testing technique of claim 1, wherein the hardware acquisition module comprises: The frequency test probe unit is arranged beside the grinding head of the grinding equipment and is opposite to the processing surface of the piezoelectric crystal to be ground, and is used for collecting an original resonance frequency signal of the piezoelectric crystal; The miniature vibration acquisition unit is integrated on the frequency test probe unit, synchronously works with the frequency test probe unit and is positioned at the same spatial point location, and is used for acquiring environmental vibration data in the grinding process, wherein the environmental vibration data at least comprises vibration frequency, amplitude and vibration intensity; The grinding head state sensing unit comprises a rotating speed sensor, a pressure sensor and a feeding amount sensor, wherein the rotating speed sensor is arranged on a driving mechanism of the grinding head and used for collecting the rotating speed of the grinding head, the pressure sensor is arranged on a pressure regulating mechanism of the grinding head and used for collecting the grinding pressure, and the feeding amount sensor is arranged on a feeding mechanism of the grinding head and used for collecting the feeding amount of the grinding head; and the industrial bus unit is connected with the frequency test probe unit, the miniature vibration acquisition unit and the grinding head state sensing unit through signals by adopting a Profinet industrial Ethernet protocol, and is used for synchronously transmitting the original resonance frequency signal, the environmental vibration data and the grinding head working parameters to the frequency test compensation module and the dynamic mapping control module, and the transmission delay is smaller than or equal to a preset delay threshold.
3. 3. The piezoelectric crystal grinding control system based on the frequency test technique according to claim 2, wherein the signal separation unit comprises: The phase alignment subunit is connected with the frequency test probe unit and the miniature vibration acquisition unit and is used for carrying out phase delay compensation on the environmental vibration data so as to enable the environmental vibration data to be in time synchronization with the original resonance frequency signal; the amplitude normalization subunit is connected with the phase alignment subunit and is used for carrying out amplitude normalization on the environment vibration signals subjected to time alignment and outputting normalized vibration signals; The frequency domain interference identification subunit is connected with the amplitude normalization subunit and is used for performing fast Fourier transform on the original resonant frequency signal and the normalized vibration signal which are aligned in time to obtain respective frequency spectrums, and identifying frequency components which are coincident with the main frequency of the vibration frequency spectrum in the original frequency spectrum through frequency matching, and marking the frequency components as vibration coupling interference frequency components; And the self-adaptive cancellation reconstruction subunit is connected with the frequency domain interference identification subunit, is internally provided with a self-adaptive filtering algorithm and is used for generating a cancellation signal according to the vibration coupling interference frequency component and the normalized vibration signal, superposing the cancellation signal with the original resonance frequency signal to eliminate vibration interference, reconstructing the residual signal by inverse Fourier transformation to obtain a resonance frequency signal of the piezoelectric crystal on the time domain, and outputting the vibration coupling interference signal to the accurate frequency calculation unit.
4. 4. The piezoelectric crystal grinding control system based on the frequency test technique according to claim 1, wherein the accurate frequency calculation unit comprises: The waveform preprocessing subunit is connected with the signal separation unit and is used for carrying out time domain analysis on the resonance frequency signal of the piezoelectric crystal, capturing transient mutation time with amplitude exceeding a preset threshold and marking the transient mutation time as a suspected abnormal period, carrying out waveform splicing on the rest effective fragments after eliminating abnormal data points, and adopting cubic spline interpolation to smooth the break points to reconstruct continuous and pure resonance frequency waveforms; The instantaneous frequency solution sub-unit is connected with the waveform preprocessing sub-unit and is used for carrying out zero crossing detection on the reconstructed waveform, calculating to obtain an instantaneous resonance frequency value and continuously outputting the instantaneous resonance frequency value in a preset period; the frequency change rate calculation subunit is connected with the instantaneous frequency solution subunit and is used for differentiating the current instantaneous resonance frequency value and the previous period value and dividing the current instantaneous resonance frequency value by the sampling period to obtain a real-time frequency change rate; The filtering and compensating subunit is respectively connected with the instantaneous frequency resolving subunit, the frequency change rate calculating subunit and the compensating coefficient library, and is used for carrying out moving average filtering on instantaneous resonance frequency values and real-time frequency change rates in a preset time window, matching corresponding frequency compensating coefficients from the compensating coefficient library as filtering weights according to the real-time vibration intensity transmitted by the hardware acquisition module, participating in weighted filtering, and finally outputting accurate resonance frequency and accurate frequency change rates.
5. 5. The piezoelectric crystal grinding control system based on frequency testing technique of claim 1, wherein the dynamic mapping model comprises: the crystal characteristic matching sub-unit is connected with the accurate frequency calculation unit and the hardware acquisition module and is used for identifying the crystal orientation and thickness of the crystal according to the initial accurate resonance frequency, matching a pre-stored crystal characteristic database and outputting a model parameter set; the characteristic fusion subunit is connected with the crystal characteristic matching subunit and is used for respectively carrying out wavelet packet decomposition, difference and short-time Fourier transform on the accurate resonance frequency, the accurate frequency change rate and the real-time vibration intensity, extracting time-frequency characteristics, trend characteristics and energy distribution characteristics and fusing the time-frequency characteristics, trend characteristics and energy distribution characteristics into fusion characteristic vectors; The deep neural network reasoning subunit is connected with the characteristic fusion subunit, is internally provided with a deep neural network configured according to the model parameter set and is used for mapping the fusion characteristic vector into basic rotating speed, basic pressure and basic feeding quantity; The nonlinear correction and verification subunit is connected with the deep neural network reasoning subunit and is used for compensating boundary errors through nonlinear correction functions, and then verifying through a process constraint rule base, clamping the overrun parameters to a safety threshold value, and generating grinding head rotating speed, grinding pressure and grinding head feeding quantity which meet safety requirements; the multi-objective optimization balancing subunit is connected with the nonlinear correction and verification subunit and is used for carrying out multi-objective optimization on three parameters according to the weight requirements of the current grinding stage on the removal rate and the surface quality, generating optimized grinding parameters and outputting the optimized grinding parameters to the vibration working condition correction unit; And the model online updating subunit is respectively connected with the multi-objective optimization balancing subunit and the model weight optimizing unit and is used for receiving the optimized parameter weight output by the model weight optimizing unit and carrying out online incremental updating on the deep neural network.
6. 6. The piezoelectric crystal grinding control system based on the frequency test technique according to claim 1, wherein the vibration condition correction unit includes: the vibration analysis grading subunit is connected with the hardware acquisition module and is used for carrying out short-time Fourier transform and wavelet packet decomposition on the real-time vibration intensity, extracting time-frequency distribution, main vibration frequency and energy aggregation characteristics and dividing the vibration intensity into normal, medium-intensity and strong impact grades according to a preset threshold interval; The decoupling and weight adjusting subunit is respectively connected with the vibration analysis grading subunit and the dynamic mapping model and is used for analyzing the differential influence coefficients of vibration on each output parameter according to the main vibration frequency and the energy characteristics, generating model weight correction coefficients by combining the vibration grades, acting on the implicit layer weight of the dynamic mapping model and realizing the dynamic adjustment of the parameter weight; The parameter local correction subunit is connected with the decoupling and weight adjustment subunit and is used for recalculating the rotating speed, the grinding pressure and the grinding head feeding amount of the grinding head according to the adjusted model and carrying out deceleration, pressure fine adjustment and deceleration local correction; The working condition judging and switching subunit is connected with the parameter local correction subunit, is internally provided with a working condition mode library and is used for judging the current working condition mode according to the vibration level and the vibration attenuation trend, and executing a corresponding parameter correction strategy, wherein the parameter correction strategy comprises small-amplitude adjustment in a stable grinding mode, active speed-down matching pressure fine adjustment in a vibration suppression mode and quick tool withdrawal matching pressure unloading in an impact protection mode; The correction output and pre-evaluation subunit is connected with the parameter local correction subunit and is used for limiting the correction amplitude of the corrected parameter, ensuring that the single correction does not exceed a safety threshold, outputting the limited correction result to the frequency drift advance pre-judging unit, pre-evaluating the correction effect according to the vibration change trend, and sending the pre-evaluation result to the model weight optimizing unit to serve as an optimization reference.
7. 7. The piezoelectric crystal grinding control system based on the frequency test technique according to claim 1, wherein the frequency drift lead prediction unit comprises: the drift pre-judging model storage subunit is internally provided with a vibration intensity-frequency drift amount pre-judging model, the vibration intensity-frequency drift amount pre-judging model is constructed by adopting a method of combining linear fitting and nonlinear correction through experiments to collect actual frequency drift amounts of piezoelectric crystals in a preset advance time window under different vibration intensities, and the fitting degree of the model is not lower than a preset fitting degree threshold; The drift pre-judging subunit is connected with the vibration working condition correction unit and the drift pre-judging model storage subunit and is used for receiving the real-time vibration intensity processed by the vibration working condition correction unit, inputting the real-time vibration intensity into the vibration intensity-frequency drift amount pre-judging model and calculating to obtain the predicted frequency drift amount in the preset lead time window; The advanced correction execution subunit is connected with the drift prejudging subunit and the vibration working condition correction unit, and is used for generating a rotating speed compensation value, a pressure compensation value and a feeding amount compensation value according to the predicted frequency drift amount, and is superposed on the corrected grinding parameter output by the vibration working condition correction unit, so as to generate a final grinding parameter instruction and output the final grinding parameter instruction to the execution driving module; the time window self-adaptive subunit is connected with the drift pre-judging subunit and is used for dynamically adjusting the length of the preset lead time window according to the change rate of the vibration intensity; The pre-judging optimizing subunit is respectively connected with the advanced correction executing subunit and the closed-loop self-calibration module, and is used for evaluating a pre-judging error according to the actual frequency convergence effect acquired by the effect acquisition unit in the closed-loop self-calibration module and carrying out on-line parameter correction on the pre-judging model in the drift pre-judging model storage subunit based on the pre-judging error.
8. 8. The piezoelectric crystal grinding control system based on frequency test technique of claim 1, wherein said execution driving module comprises: the command analysis and distribution unit is connected with the frequency drift advanced pre-judging unit and is used for receiving and analyzing the target rotating speed, the pressure and the feeding quantity value and distributing the target rotating speed, the pressure and the feeding quantity value to the corresponding driving channel; The feedforward compensation unit is connected with the instruction analysis and distribution unit and is used for performing feedforward compensation on the target value according to the inertia and response delay characteristics of the executing mechanism to generate a driving instruction with an advance compensation quantity; the rotating speed driving unit is connected with the feedforward compensation unit and is used for receiving a rotating speed driving instruction, driving the grinding head spindle motor to reach a target rotating speed and feeding back an actual rotating speed; The pressure driving unit is connected with the feedforward compensation unit and is used for receiving a pressure driving instruction, controlling the pressure executing cylinder to output target pressure and feeding back actual pressure; the feed driving unit is connected with the feed compensation unit and is used for receiving a feed driving instruction, driving the feed servo motor to move according to the target feed amount and feeding back the actual position; The multi-axis coordination unit is respectively connected with each driving unit and is used for monitoring the response state of each driving unit, and when the response lag of any unit exceeds a preset synchronous deviation threshold value, a waiting or decelerating instruction is sent out to ensure the coordination of time sequences; the state self-checking unit is connected with the multi-axis cooperative unit and is used for collecting the temperature and current states of each driving unit in real time and sending out a protective instruction when the parameters exceed the operation safety threshold; And the execution effect feedback unit is respectively connected with each driving unit and the effect acquisition unit and is used for packaging the actually achieved rotating speed, pressure and feeding amount into execution effect data and transmitting the execution effect data to the effect acquisition unit.
9. 9. The piezoelectric crystal grinding control system based on the frequency test technique of claim 1, wherein the effect acquisition unit comprises: the execution data capturing subunit is connected with the execution driving module and is used for capturing the rotation speed, the pressure and the feeding value actually reached by the grinding head after the grinding parameters are adjusted, and recording the adjustment time and the duration; the frequency final value acquisition subunit is connected with the frequency test compensation module and is used for acquiring actual resonance frequency values and space position coordinates of a plurality of sampling points of the piezoelectric crystal machining surface after grinding; the frequency convergence analysis subunit is connected with the frequency final value acquisition subunit and is used for calculating the average value, the polar difference and the standard deviation of the crystal face frequency, comparing the target frequency threshold value and outputting the crystal face frequency consistency index and the frequency standard reaching rate; the convergence rate calculation subunit is respectively connected with the execution data capturing subunit and the frequency final value acquisition subunit and is used for calculating the actual frequency convergence rate according to the time difference and the frequency variation of the adjustment time and the grinding completion time; The frequency spectrum purity analysis subunit is connected with the frequency final value acquisition subunit and is used for carrying out Fourier transform on the actual frequency value, analyzing the energy duty ratio of the spurious frequency and outputting a frequency spectrum purity coefficient; the grinding effect comprehensive evaluation subunit is respectively connected with the frequency convergence analysis subunit, the convergence rate calculation subunit and the frequency spectrum purity analysis subunit and is used for weighting and fusing all indexes to generate a grinding effect comprehensive score; the abnormal grinding identification subunit is connected with the grinding effect comprehensive evaluation subunit and is used for outputting an abnormal mark when the comprehensive score is lower than a preset qualified threshold; And the data packaging and transmitting subunit is respectively connected with the grinding effect comprehensive evaluation subunit, the abnormal grinding identification subunit, the compensation coefficient correction unit and the model weight optimization unit and is used for packaging the effect score, the abnormal mark and the data of each sampling point into effect feedback data and synchronously transmitting the effect feedback data to the compensation coefficient correction unit and the model weight optimization unit.
10. 10. The piezoelectric crystal grinding control system based on the frequency test technique according to claim 1, wherein the compensation coefficient correction unit comprises: The deviation calculation subunit is connected with the effect acquisition unit and is used for receiving an actual frequency convergence effect, comparing the crystal face frequency average value with a target frequency threshold value to obtain a frequency steady-state deviation, and comparing the actual frequency convergence rate with a target convergence rate to obtain a rate dynamic deviation; The vibration working condition backtracking subunit is connected with the hardware acquisition module and is used for calling real-time vibration intensity time sequence data of the current grinding and extracting average vibration intensity and peak vibration intensity in a key stage; The deviation-vibration association analysis subunit is respectively connected with the deviation calculation subunit and the vibration working condition backtracking subunit and is used for carrying out association analysis on frequency deviation, rate deviation and vibration intensity, identifying under-compensation and over-compensation areas of compensation coefficients under different vibration intensities and generating a deviation distribution map; The compensation coefficient correction calculation operator unit is connected with the deviation-vibration association analysis subunit and is used for calculating compensation coefficient correction corresponding to each vibration intensity level according to the deviation distribution map and a preset correction step factor; the coefficient library updating subunit is respectively connected with the compensation coefficient correction calculation operator unit and the compensation coefficient library and is used for carrying out increment updating on the frequency compensation coefficient corresponding to the vibration intensity level in the compensation coefficient library according to the correction quantity; The correction effect verification subunit is connected with the coefficient library updating subunit and is used for acquiring an actual frequency convergence effect after the next grinding is finished, comparing the deviation improvement degree, and triggering secondary correction when the improvement degree is lower than a preset improvement threshold value; the aging trend analysis subunit is connected with the compensation coefficient correction calculation operator unit and is used for counting the change trend of the compensation coefficient correction amount in multiple grinding and judging the drift rule of the compensation coefficient along with equipment aging; And the synchronous output subunit is respectively connected with the coefficient library updating subunit and the model weight optimizing unit and is used for synchronously transmitting the key parameters corrected by the compensation coefficient to the model weight optimizing unit as an optimization reference.

Description

Piezoelectric crystal grinding control system based on frequency test technology Technical Field The invention relates to the technical field of piezoelectric crystal processing and industrial automatic control, in particular to a piezoelectric crystal grinding control system based on a frequency test technology. Background The piezoelectric crystal has good piezoelectric effect and stable frequency characteristic, and is widely applied to various frequency control and signal processing electronic devices. The resonance frequency parameter is one of the core indexes for measuring the performance of the product, and the thickness control precision of the crystal in the grinding processing stage directly influences the consistency and stability of the final frequency. Therefore, accurate test and dynamic regulation and control of the resonance frequency are realized in the grinding process, and the method is a key link for improving the yield and the processing consistency of products. In the actual production process, the grinding processing of the piezoelectric crystal is usually accompanied with complex working conditions such as high-speed rotation, mechanical contact, fluid disturbance and the like, and the multi-source vibration coupling phenomenon exists in the system operation environment. The resonance frequency test signal is easy to be overlapped or coupled with the environmental vibration signal in the acquisition process, so that the fluctuation of the frequency measurement result is unstable. If the interference components in the test signal are not effectively distinguished and processed, the accuracy of the subsequent control decision is affected. Meanwhile, the piezoelectric crystal material has anisotropic characteristics, and the frequency variation of the piezoelectric crystal material shows nonlinear characteristics along with the thickness variation in the processing process. There is a complex coupling relationship between the milling parameters (e.g., rotational speed, pressure, feed) and frequency. In actual control, if parameter adjustment is performed based on only a single frequency value, and the frequency change trend and the current vibration working condition are not comprehensively considered, accurate matching control on the frequency change process is difficult to realize, and problems of adjustment lag or excessive correction are easy to occur. In addition, in the existing processing system, frequency test and grinding control often belong to different functional units, test results are directly used as control inputs, a dynamic correction mechanism for the validity of test data is lacked, and an adaptive feedback structure based on the processing results is not formed. As the equipment operating time increases or the operating conditions change, system parameters may deviate from the initial set state, and if the self-calibration and self-optimization capabilities are lacking, the frequency control accuracy gradually decreases. Therefore, it is needed to construct a piezoelectric crystal grinding control system capable of effectively separating and compensating frequency signals under complex vibration conditions, performing deep coupling on frequency test results and grinding parameter control, and simultaneously having dynamic mapping and closed-loop self-calibration capabilities, so as to improve frequency control precision and processing stability. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a piezoelectric crystal grinding control system based on a frequency test technology, which is used for carrying out separation compensation on a frequency test signal under a complex vibration working condition so as to eliminate vibration interference, carrying out deep coupling control on accurate frequency data and grinding parameters through a dynamic mapping model and an advanced prejudging unit, and simultaneously realizing self-optimization of system parameters by combining a closed-loop self-calibration module so as to improve frequency test precision and grinding control stability. In order to achieve the above purpose, the invention provides a piezoelectric crystal grinding control system based on a frequency test technology, comprising: The hardware acquisition module acquires original resonance frequency signals, vibration intensity and grinding head working parameters; The frequency test compensation module is connected with the hardware acquisition module and comprises: the signal separation unit is used for receiving the original resonance frequency signal and the vibration intensity and outputting a crystal resonance signal and a vibration interference signal; The accurate frequency calculation unit is connected with the signal separation unit and a preset compensation coefficient library and is used for calculating accurate resonance frequency and change rate of the accurate resonance frequency according t