An acoustic resonant frequency search system for an ultrasonic knife

Abstract

The application discloses an acoustic resonance frequency search system of an ultrasonic knife, comprising a multimodal signal acquisition module, a characteristic parameter calculation module, a target function construction module, a resonance frequency search optimization module, a closed-loop frequency control module, a dynamic tracking and protection module and a parameter self-adaptive module. The system synchronously acquires signals such as driving voltage, current, phase difference, impedance and knife head amplitude, calculates complex impedance and its derivative, and constructs a comprehensive target function; based on an intelligent optimization algorithm, the optimal resonance frequency is quickly searched out, and then, in combination with load compensation and closed-loop adjustment, real-time tracking control of the frequency is realized; meanwhile, the smooth output and the multi-dimensional protection mechanism guarantee the operation stability and safety. The application can realize high-precision, high real-time and high-robustness resonance frequency search, effectively improve the energy utilization efficiency, cutting and coagulation performance and surgical safety of the ultrasonic knife, and is suitable for dynamic tuning and intelligent control of multiple types of ultrasonic knives.

Description

Technical Field

[0001] This invention relates to the field of acoustic control and intelligent tuning technology for ultrasonic surgical equipment, and more specifically, to an acoustic resonant frequency search system for an ultrasonic scalpel. Background Technology

[0002] An ultrasonic scalpel is an advanced surgical instrument that transmits high-frequency ultrasonic vibration energy to tissue through a transducer and a blade, achieving tissue cutting and coagulation. Its basic principle is to utilize a piezoelectric ceramic transducer to generate high-frequency mechanical vibration at a specific frequency, and then transmit this vibration to the tissue through the blade, causing tissue proteins to denature, break down, or coagulate. Due to its advantages such as minimal trauma, less bleeding, and faster recovery, the ultrasonic scalpel has been widely used in various surgeries, including thyroid, breast, hepatobiliary, and laparoscopic surgeries. However, the performance of an ultrasonic scalpel is highly dependent on the precise matching of the driving frequency and the acoustic resonant frequency. When the driving frequency is consistent with or close to the resonant frequency, the blade amplitude reaches its maximum, energy transfer efficiency is optimal, and the cutting and coagulation effects are significantly improved. Once it deviates from the resonant point, the amplitude decreases significantly, energy utilization is reduced, and it may lead to incomplete cutting, inadequate hemostasis, or even damage to the transducer due to overload. Therefore, quickly and accurately searching for and locking the acoustic resonant frequency is crucial to improving the safety, stability, and surgical outcomes of the ultrasonic scalpel.

[0003] Current technologies for searching and adjusting acoustic resonant frequencies still have several shortcomings. First, traditional systems often employ a fixed-step scanning frequency method, traversing the entire frequency range in steps of tens or hundreds of hertz. While simple, this method lacks precision, especially under dynamic loads where accurately locating the optimal resonant point is difficult, leading to decreased cutting efficiency and energy utilization. Second, factors such as tissue hardness, temperature, humidity, and blade wear during surgery can cause changes in load conditions, resulting in resonant frequency drift. Traditional single-frequency drive or single-parameter feedback methods cannot achieve dynamic compensation, causing output power fluctuations, amplitude instability, and even risks of tissue carbonization or transducer damage. Third, most existing devices rely solely on single signals of current or voltage for judgment, neglecting multi-dimensional information such as impedance amplitude, phase difference, and amplitude feedback, leading to incomplete judgment criteria and insufficient algorithm robustness. Fourth, traditional serial scanning and threshold-based control strategies have slow response speeds and significant frequency adjustment lags, failing to meet the real-time and high stability requirements of surgical procedures. Fifth, some devices lack frequency offset protection and overload alarm mechanisms, and cannot intervene in a timely manner under frequency drift or abnormal load conditions, which poses a risk of equipment damage and surgery.

[0004] Therefore, there is an urgent need for an acoustic resonant frequency search system for ultrasonic scalpels to solve these problems. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems mentioned in the background section and to provide an acoustic resonant frequency search system for an ultrasonic scalpel, comprising:

[0006] Multimodal signal acquisition module: configured to acquire signals in the frequency range Internal synchronous acquisition of drive voltage Drive current Phase difference between voltage and current and the amplitude of the cutting head ,in and These are the lower and upper limits of search frequency, respectively.

[0007] Characteristic parameter calculation module: connected to the multimodal signal acquisition module, configured to calculate complex impedance according to the following formula:

[0008]

[0009] in For complex impedance , For driving voltage, For driving current, Given the phase difference between voltage and current; and calculate the impedance magnitude:

[0010]

[0011] in This is the impedance amplitude. The real part of the impedance. This represents the imaginary part of the impedance; simultaneously, the frequency derivative of the reactance is calculated using the center difference:

[0012]

[0013] in For the frequency derivative of the reactance, The derivative step size;

[0014] Objective function construction module: Connected to the characteristic parameter calculation module, configured to construct an objective function based on phase, impedance, and reactance derivative.

[0015]

[0016] in To calculate the overall search score, These are the weighting coefficients. This is the normalized scaling coefficient;

[0017] The resonant frequency search and optimization module is connected to the objective function construction module and is configured to update particle velocity and position through particle swarm optimization.

[0018]

[0019] in For the first The second iteration The speed of each particle For inertial weights, As an acceleration factor, A random number between 0 and 1. and These are the individual optimal frequency and the global optimal frequency, respectively.

[0020]

[0021] in For particle position; score is obtained through iterative search. The minimum frequency is taken as the resonant frequency. ;

[0022] Closed-loop frequency control module: connected to the resonant frequency search and optimization module, configured to generate the output frequency by combining load compensation and PI regulation.

[0023]

[0024] in For output frequency, For PI adjustment, This is the load compensation amount;

[0025] Dynamic tracking and protection module: connected to the closed-loop frequency control module, configured to obtain the command frequency through first-order smoothing.

[0026]

[0027] in The current smooth output frequency, As a smoothing coefficient; and monitored in real time. With reference frequency And amplitude deviation; if abnormal conditions are met, protection will be triggered.

[0028] As a preferred embodiment of the present invention, the objective function construction module includes a normalization and weighting unit, used to calculate based on the maximum value of the local window:

[0029]

[0030] in To prevent constants with zero denominators; and to set: , These are the weighting coefficients. This is the normalized scaling coefficient.

[0031] As a preferred technical solution of the present invention, the derivative estimation unit in the feature parameter calculation module solves the problem by central difference. The result is directly used in the objective function. The third calculation.

[0032] As a preferred technical solution of the present invention, the inertial weight in the resonant frequency search and optimization module With the number of iterations Linear decrease:

[0033]

[0034] in and These are the upper and lower limits (dimensionless) of the inertia weight, respectively. This represents the maximum number of iterations.

[0035] As a preferred embodiment of the present invention, the load compensation amount in the closed-loop frequency control module is:

[0036]

[0037] in The load compensation frequency (Hz) is used. The compensation factor (Hz) For reference amplitude (μm), This represents the real-time amplitude.

[0038] As a preferred embodiment of the present invention, the closed-loop frequency control module includes a PI control unit, wherein the PI adjustment amount is:

[0039]

[0040] in For PI-regulated output (Hz), and These are the proportional and integral coefficients, respectively. This represents the phase error.

[0041] As a preferred technical solution of the present invention, the smoothing coefficient of the dynamic tracking module With the objective function The adjustment improves the smoothness of the output frequency in a stable state and reduces the fluctuation of the output frequency.

[0042] As a preferred technical solution of the present invention, the system adopts an FPGA+DSP dual-processing architecture: the FPGA realizes signal acquisition and synchronous phase measurement, with a sampling frequency of not less than 200kHz and a phase measurement resolution of not less than The DSP performs impedance calculation, objective function solution, particle swarm optimization, compensation and control algorithms, with end-to-end update time not exceeding 20ms.

[0043] As a preferred technical solution of the present invention, the dynamic protection module triggers protection when the following conditions are met:

[0044] Command frequency deviation exceeds threshold:

[0045]

[0046] Amplitude deviation exceeds the threshold:

[0047]

[0048] in For frequency deviation threshold, This is the amplitude deviation threshold.

[0049] As a preferred technical solution of the present invention, the system includes a parameter library, which is configured according to the transducer model. and blade length Automatic settings:

[0050]

[0051] in For the center frequency, For the initial frequency range, and for Provide initial values ​​to enable adaptive tuning among multiple device models.

[0052] Beneficial Effects: This invention achieves rapid and accurate positioning of the resonant frequency through the organic combination of multimodal signal acquisition and intelligent optimization algorithms, significantly improving the matching accuracy between the ultrasonic scalpel driving frequency and the acoustic resonant frequency. The system can stably output high-efficiency amplitudes, enabling more complete energy transfer, thereby effectively improving the efficiency and quality of tissue cutting and coagulation, meeting the clinical needs for high-precision surgery.

[0053] This invention possesses excellent dynamic adaptability. By integrating amplitude feedback and phase error signals, combined with load compensation and closed-loop control strategies, it can achieve real-time automatic adjustment when conditions such as tissue hardness, thickness, or blade wear change, ensuring that the ultrasonic scalpel always maintains its optimal resonance state. This not only improves the continuity and stability of the surgical procedure but also provides reliable assurance for precise operations in complex environments.

[0054] This invention also incorporates a comprehensive safety protection mechanism, including frequency offset protection, amplitude anomaly alarm, and overload power reduction. When the equipment malfunctions, the system automatically intervenes and adjusts its operating strategy, effectively preventing transducer damage and surgical risks. This multi-layered safety design significantly improves the reliability of equipment operation and the safety of the surgical procedure, extends equipment lifespan, and reduces maintenance costs. Attached Figure Description

[0055] Figure 1 This is a system block diagram of an acoustic resonant frequency search system for an ultrasonic scalpel proposed in this invention;

[0056] Figure 2 This is a processing architecture diagram of an acoustic resonant frequency search system for an ultrasonic scalpel proposed in this invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-2 The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0058] Example 1: This invention discloses an acoustic resonant frequency search system for an ultrasonic scalpel. Through multi-modal signal acquisition, characteristic parameter calculation, optimization algorithm solution, closed-loop control, and dynamic protection, it achieves rapid, accurate, and stable search for the ultrasonic scalpel's resonant frequency, and maintains the scalpel system in optimal resonant state even under varying surgical loads. The system mainly consists of a multi-modal signal acquisition module, a characteristic parameter calculation module, an objective function construction module, a resonant frequency search and optimization module, a closed-loop frequency control module, a dynamic tracking and protection module, and a parameter adaptive module. The hardware platform adopts an FPGA and DSF collaborative architecture to achieve high-speed data acquisition, parallel computing, and real-time control.

[0059] In the specific implementation process, the multi-mode signal acquisition module first searches within the set frequency range. Internally, synchronously acquire drive voltage Drive current Phase difference between voltage and current and the amplitude of the cutting head ,in, and Based on the parameter library according to the transducer model and blade length Automatic settings, such as center frequency 55kHz, initial bandwidth If it is 500Hz, then After the data acquisition is completed, the characteristic parameter calculation module uses the acquired signal to calculate the complex impedance:

[0060]

[0061] in, For complex impedance, the unit is . This is the driving voltage, measured in volts (V). This is the driving current, measured in amperes (A). The phase difference between voltage and current, expressed in degrees or radians.

[0062] The complex impedance is decomposed into its real part. and the imaginary part of impedance Then calculate the impedance magnitude:

[0063]

[0064] in, Impedance amplitude, in units of .

[0065] To obtain the sensitivity of the reactance as a function of frequency, the module also calculates the frequency derivative of the reactance using the central difference method:

[0066]

[0067] in, This is the frequency derivative of the reactance, in Ω / Hz. This represents the differential step size, in Hz. The calculated value is... , and It is fed into the objective function building module.

[0068] In the local search window Within the window, the system first calculates the normalization factor based on the maximum value within the window:

[0069]

[0070] in, To prevent small constants with a denominator of zero, weighting coefficients are then generated based on the normalization factor:

[0071]

[0072] These parameters, together with the collected data, construct the comprehensive search scoring function:

[0073]

[0074] This function The system comprehensively considers phase difference, impedance amplitude, and reactance change rate; lower values ​​indicate proximity to the true resonant point. The resonant frequency search and optimization module employs an improved particle swarm optimization algorithm, iteratively solving for the optimal frequency across the entire search range. For the [missing value]... The iteration of the ... For each particle, the formulas for updating its velocity and position are:

[0075]

[0076]

[0077] in, For speed (Hz / iteration), For position (Hz), For inertial weights, As an acceleration factor, It is a random number. and These are the individual optimal frequency and the global optimal frequency, respectively. The inertia weight decreases linearly with the number of iterations.

[0078]

[0079] This ensures a wide scope of early exploration and high accuracy in later searches.

[0080] After the iteration, the overall search score was calculated. The position with the minimum value is the optimal resonant frequency. Closed-loop frequency control module receives It also incorporates load and phase error information for compensation and adjustment.

[0081] The load compensation term is based on the reference amplitude. and real-time amplitude calculate:

[0082]

[0083] in, To compensate for the frequency (Hz), This is the compensation coefficient. Phase error. This is used for PI control:

[0084]

[0085] in, and These are the proportional and integral coefficients, respectively. The final output frequency is:

[0086]

[0087] To avoid excessive fluctuations in the output frequency, the dynamic tracking module... Perform first-order smoothing:

[0088]

[0089] in, This is the smoothed instruction frequency. This is the smoothing coefficient.

[0090] The command frequency is not only used as a drive signal input to the power amplifier module, but also used in real time for protection judgment: when or In such cases, the system will automatically reduce power output or trigger an alarm to ensure safe operation of the equipment.

[0091] The parameter adaptive module is based on the transducer model. and blade length ,for These parameters provide reasonable initial values, enabling rapid migration and adaptive tuning between different equipment models.

[0092] like Figure 2 As shown, in terms of hardware, the FPGA is used for high-speed signal acquisition and synchronous measurement, with a phase resolution better than 0.1° and a sampling rate of no less than 200kHz; the DSP is responsible for running impedance calculation, objective function solution, particle swarm optimization, and closed-loop control algorithms. The total delay of a single search and adjustment is controlled within 20ms, which can meet the requirements of rapid response during surgery. Actual tests show that the system can lock the optimal resonant frequency within 20ms, with a frequency error not exceeding ± Under no-load, light-load, and high-load conditions, the scalpel maintains a blade amplitude fluctuation of less than 0.5%, significantly outperforming traditional fixed-step or single-parameter feedback control methods. Through the aforementioned chain algorithm and closed-loop adjustment, this invention achieves an organic integration of frequency search, compensation, output, and protection, significantly improving the energy utilization, cutting efficiency, and system stability of the ultrasonic scalpel in the surgical environment.

[0093] Example 2: In a laparoscopic cholecystectomy, the surgeon used an ultrasonic scalpel equipped with the acoustic resonant frequency search system of this invention. Before the surgery began, the system automatically set the search frequency range from the parameter library based on the transducer model and scalpel head length. kHz to The FPGA-controlled multimodal signal acquisition module synchronously acquires the drive voltage at a rate of 200 kHz, providing initial values ​​for the load compensation coefficient, Pl parameter, and smoothing coefficient. Upon device startup, the FPGA-controlled multimodal signal acquisition module synchronously acquires the drive voltage at a rate of 200 kHz. Current Phase difference and the amplitude of the cutting head It transmits the data to the DSP unit for processing in real time.

[0094] The DSP first calculates the complex impedance. Decompose it into real part and the virtual part And further calculate the impedance magnitude With reactance derivative Subsequently, the system constructs a comprehensive objective function near the current frequency. And use particle swarm optimization algorithm to quickly search for resonant frequencies. After iteration, the optimal resonant point is obtained and used as the initial driving frequency output.

[0095] During surgery, as the surgeon cuts different tissues, the load on the surgical tip changes continuously, causing the tip's amplitude to fluctuate. With reference amplitude If a deviation occurs, the load compensation unit will adjust accordingly. Calculate the compensation frequency and compare it with the phase error. PI control output Stacked together Above, a new output frequency is formed. To ensure the stability of the output frequency, the dynamic tracking module... Smoothing is performed to obtain a stable instruction frequency. It also drives the power amplifier module in real time.

[0096] During a certain cutting stage, the tissue stiffness suddenly increased, causing a drastic change in impedance. The system detected a frequency deviation approaching a preset threshold. It also triggers a protection mechanism, automatically reducing output power and alerting the operator to the blade load status. Once tissue cutting is complete, the frequency deviation is eliminated, and the system automatically returns to normal power output, ensuring the continuity and safety of the surgical procedure.

[0097] Throughout the entire surgical procedure, the system maintained a high degree of consistency between its frequency and resonant point, ensuring stable blade amplitude, smooth cutting, significant hemostasis, and no overload during operation. This embodiment demonstrates that the present invention can achieve rapid resonant frequency search, dynamic compensation, and safety protection in complex surgical environments, significantly improving the clinical performance and surgical safety of the ultrasonic scalpel.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An acoustic resonant frequency search system for an ultrasonic scalpel, characterized in that, include: Multimodal signal acquisition module: configured to acquire signals in the frequency range Internal synchronous acquisition of drive voltage Drive current Phase difference between voltage and current and the amplitude of the cutting head ,in and These are the lower and upper limits of search frequency, respectively. Characteristic parameter calculation module: connected to the multimodal signal acquisition module, configured to calculate complex impedance according to the following formula: in For complex impedance , For driving voltage, For driving current, Given the phase difference between voltage and current; and calculate the impedance magnitude: in The impedance amplitude, This is the real part of the impedance. This represents the imaginary part of the impedance; simultaneously, the frequency derivative of the reactance is calculated using the center difference: in For the frequency derivative of the reactance, The derivative step size; Objective function construction module: Connected to the characteristic parameter calculation module, configured to construct an objective function based on phase, impedance, and reactance derivative. in To calculate the overall search score, These are the weighting coefficients. This is the normalized scaling coefficient; The resonant frequency search and optimization module is connected to the objective function construction module and is configured to update particle velocity and position through particle swarm optimization. in For the first The second iteration The speed of each particle For inertial weights, As an acceleration factor, A random number between 0 and 1. and These are the individual optimal frequency and the global optimal frequency, respectively. in For particle position; score is obtained through iterative search. The minimum frequency is taken as the resonant frequency. ; Closed-loop frequency control module: connected to the resonant frequency search and optimization module, configured to generate the output frequency by combining load compensation and PI regulation. in For output frequency, For PI adjustment, This is the load compensation amount; Dynamic tracking and protection module: connected to the closed-loop frequency control module, configured to obtain the command frequency through first-order smoothing. in The current smooth output frequency, As a smoothing coefficient; and monitored in real time. With reference frequency And amplitude deviation; if abnormal conditions are met, protection will be triggered.

2. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The objective function construction module is used for calculating the maximum value of a local window. in To prevent constants with zero denominators; and to set: , These are the weighting coefficients. This is the normalized scaling coefficient.

3. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The derivative estimation unit in the feature parameter calculation module solves the problem through central difference. The result is directly used in the objective function. The calculation.

4. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The inertial weight in the resonant frequency search and optimization module With the number of iterations Linear decrease: in and These are the upper and lower limits of the inertia weight, respectively. This represents the maximum number of iterations.

5. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The load compensation amount in the closed-loop frequency control module is: in For load compensation frequency, For compensation coefficient, For reference amplitude, This represents the real-time amplitude.

6. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The closed-loop frequency control module includes a PI control unit, and the PI adjustment value is: in For PI-regulated output (Hz), and These are the proportional and integral coefficients, respectively. This represents the phase error.

7. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The smoothness coefficient of the dynamic tracking module With the objective function Adjustment.

8. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The system adopts an FPGA+DSP dual-processing architecture: the FPGA implements signal acquisition and synchronous phase measurement, with a sampling frequency of no less than 200kHz and a phase measurement resolution of no less than [missing information]. The DSP performs impedance calculation, objective function solution, particle swarm optimization, compensation and control algorithms, with end-to-end update time not exceeding 20ms.

9. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The dynamic protection module triggers protection when the following conditions are met: Command frequency deviation exceeds threshold: Amplitude deviation exceeds the threshold: in For frequency deviation threshold, This is the amplitude deviation threshold.

10. The acoustic resonant frequency search system for an ultrasonic scalpel according to claim 1, characterized in that, The system includes a parameter library, based on the transducer model. and blade length Automatic settings: in For the center frequency, For the initial frequency range, and for Provide initial values.

Images