Calibration device and method for impedance measured value of ultrasonic soft tissue scalpel host

Abstract

The invention discloses a device and a method for calibrating an impedance measured value of an ultrasonic soft tissue scalpel host. The method is executed by an upper computer, and comprises the following steps: switching on an impedance measurement unit, sending a sweep frequency measurement instruction to the impedance measurement unit according to a set frequency range, and obtaining corresponding first impedance data and actual working frequency; switching on a to-be-calibrated host, sending a plurality of driving frequency signals one by one through the to-be-calibrated host, and calculating second impedance data according to the sampling values obtained under each driving frequency; executing optimal fitting according to the first impedance data and the second impedance data and calculating a compensation coefficient; and re-testing the target frequency point according to the compensation coefficient, and if the calibrated measurement error is smaller than a preset value, determining that the verification is passed, otherwise, determining that the verification is not passed. By integrating impedance multi-frequency-point measurement, an interpolation algorithm and an optimal fitting technology, measurement errors caused by factors of a host can be effectively compensated, and more accurate impedance calibration is achieved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of medical device detection, and in particular to a device and method for calibrating impedance measurement values ​​of an ultrasonic soft tissue surgical knife host. Background Art

[0002] Ultrasonic soft tissue scalpel is an important instrument in modern minimally invasive surgery. The accurate measurement of the impedance of the transducer and the scalpel rod by the host during its operation is directly related to the safety of the operation and the cutting effect.

[0003] At present, the impedance measurement of the ultrasonic scalpel host is obtained by an indirect calculation method. The resonant frequency of the ultrasonic transducer is tracked by a frequency tracking algorithm, and the voltage and current peaks output by the host are obtained by a high-speed sampling circuit to calculate the impedance parameters. The prior art has not calibrated the impedance measurement of the ultrasonic surgical scalpel host. For example, the calibration method involved in application number CN202110118202.6 mainly involves the calibration of the host current output to compensate for the impact of the transducer performance change without optimizing or compensating the impedance measurement of the host itself.

[0004] The existing host impedance measurement method has the following defects: First, due to the error of the sampling circuit itself and the temperature drift effect, the voltage and current sampling values ​​are biased, which in turn affects the impedance calculation accuracy; second, the characteristics of the components of the host will change during long-term operation, but the existing measurement method lacks a calibration mechanism and cannot detect and correct the impedance measurement deviation in time. These problems may lead to measurement consistency deviations and output power control deviations between different hosts, which is not conducive to the host algorithm's regulation of the blade vibration characteristics, and ultimately affects the safety and effectiveness of the surgery. Summary of the invention

[0005] To solve the above problems, the present invention provides a device and method for calibrating the impedance measurement value of an ultrasonic soft tissue scalpel host. The method can effectively compensate for the measurement error caused by the host's own factors and achieve more accurate impedance calibration through comprehensive impedance multi-frequency point measurement, interpolation algorithm and optimization fitting technology.

[0006] In a first aspect, an embodiment of the present invention provides a device for calibrating impedance measurement values ​​of an ultrasonic soft tissue surgical knife host, comprising:

[0007] Host computer, impedance measurement unit, host to be calibrated and standard device;

[0008] The impedance measurement unit is connected to the host computer and the standard device respectively;

[0009] The host to be calibrated is connected to the host computer and the standard device respectively.

[0010] Optionally, the standard device is a standard impedance element with known impedance.

[0011] In a second aspect, an embodiment of the present invention further provides a method for calibrating an impedance measurement value of an ultrasonic soft tissue surgical knife host, the method being executed by a host computer and comprising:

[0012] Control the switching circuit to switch on the impedance measurement unit, send a frequency sweep measurement instruction to the impedance measurement unit according to the set frequency range, and obtain corresponding first impedance data and actual operating frequency;

[0013] Control the switching circuit to connect the host to be calibrated, send multiple driving frequency signals one by one through the host to be calibrated, and calculate the second impedance data according to the sampling values ​​obtained at each driving frequency;

[0014] Performing optimization fitting and calculating a compensation coefficient according to the first impedance data and the second impedance data;

[0015] The target frequency point is retested according to the compensation coefficient. If the measurement error after calibration is less than the preset value, the verification passes; otherwise, the verification fails.

[0016] Optionally, sending a frequency sweep measurement instruction to the user according to a set frequency range and obtaining corresponding first impedance data and an actual operating frequency includes:

[0017] Obtain the impedance amplitude and the impedance phase angle corresponding to each frequency point and form a data pair;

[0018] Obtain two adjacent frequency points corresponding to the phase changing from negative to positive and the phase angles corresponding to the two frequency points;

[0019] According to the two adjacent frequency points corresponding to the phase changing from negative to positive and the phase angles corresponding to the two frequency points, an interpolation algorithm is used to calculate the frequency corresponding to when the phase angle is 0, and the frequency is used as the actual operating frequency.

[0020] Optionally, the host to be calibrated sends driving signals of multiple driving frequencies one by one and calculates the second impedance data according to the sampling values ​​obtained at each driving frequency, including:

[0021] Setting a plurality of driving frequencies around the actual working frequency and sending driving signals of the plurality of driving frequencies one by one through the host to be calibrated;

[0022] The host to be calibrated obtains the voltage and current sampling peak values ​​and the voltage and current phase differences at each driving frequency, and calculates the impedance value corresponding to each driving frequency point according to the voltage and current sampling peak values, thereby obtaining the second impedance data.

[0023] Optionally, performing post-optimization fitting and calculating a compensation coefficient according to the first impedance data and the second impedance data includes:

[0024] Establishing an error model according to the first impedance value and the second impedance value;

[0025] Solving the compensation coefficient of the error model and calculating the compensation relationship by an optimization algorithm;

[0026] Optionally, the error model includes an amplitude error model and a phase error model.

[0027] The present invention provides a device and method for calibrating the impedance measurement value of an ultrasonic soft tissue scalpel host. The method realizes all-round verification of the host impedance measurement accuracy through multi-band driving signals and multiple measurements. In addition, the method can effectively correct the impedance measurement deviation of the host by fitting impedance data and calculating a compensation coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A structural diagram of a device for calibrating impedance measurement of an ultrasonic soft tissue surgical knife host provided by an embodiment of the present invention;

[0029] Figure 2 A flow chart of a method for calibrating impedance measurement values ​​of an ultrasonic soft tissue surgical knife host provided by an embodiment of the present invention;

[0030] Figure 3 A detailed flow chart of a method for calibrating impedance measurement values ​​of an ultrasonic soft tissue surgical knife host provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0032] Example

[0033] An embodiment of the present invention provides a device for calibrating the impedance measurement value of an ultrasonic soft tissue surgical knife host, wherein the device includes: a host computer, an impedance measurement unit, a host to be calibrated and a standard device; the impedance measurement unit is connected to the host computer and the standard device respectively; the host to be calibrated is connected to the host computer and the standard device respectively.

[0034] As an example, the device can use a switching circuit to implement circuit switching, see Figure 1 .

[0035] In this embodiment, the impedance measurement unit, the host to be calibrated and the switching circuit are respectively connected to a host computer; the impedance measurement unit and the host to be calibrated are respectively connected through a switching circuit and a standard device.

[0036] The above-mentioned standard device may be a standard impedance element with known impedance.

[0037] Specifically, the host computer is used to control the working status of the impedance analyzer, the switching circuit, and the host to be calibrated, and complete functions such as data collection, calculation, fitting, and uploading compensation coefficients.

[0038] The impedance measurement unit is used to obtain the impedance data of the standard transducer or standard impedance element, supports frequency sweep measurement and returns the data to the host computer. The impedance measurement unit in this embodiment includes but is not limited to an impedance analyzer or an LCR impedance measurement bridge. Figure 1 The impedance analyzer is used as an example. The host to be calibrated includes an impedance measurement module, and can generate corresponding current drive according to the drive signal, and sample voltage and current values ​​for impedance calculation.

[0039] The switching circuit is used to switch switches S1 and S2 to control the conversion between different working modes.

[0040] Furthermore, in this embodiment, circuit switching can be performed manually when measuring different impedance data.

[0041] See also Figure 2 The present invention also provides a method for calibrating the impedance measurement value of an ultrasonic soft tissue surgical knife host, comprising:

[0042] Turning on the impedance analyzer, sending a frequency sweep measurement instruction to the impedance analyzer according to the set frequency range and obtaining corresponding first impedance data and actual operating frequency;

[0043] Connecting the host to be calibrated, sending a plurality of driving frequency signals one by one through the host to be calibrated, and calculating the second impedance data according to the sampling values ​​obtained at each driving frequency;

[0044] Performing optimization fitting and calculating a compensation coefficient according to the first impedance data and the second impedance data;

[0045] The target frequency point is retested according to the compensation coefficient. If the measurement error after calibration is less than the preset value, the verification passes; otherwise, the verification fails.

[0046] Continue to see Figure 3 The present invention provides a method for calibrating the impedance measurement value of an ultrasonic soft tissue surgical knife host, which specifically comprises the following steps:

[0047] S1, the host computer controls the switching circuit, turns on switch S1, and turns off switch S2.

[0048] S2. The host computer sends a frequency sweep measurement instruction to the impedance analyzer according to the set frequency range, obtains the corresponding first impedance data and transmits it back to the host computer.

[0049] S3. The host computer executes an interpolation algorithm according to the first impedance data Z1 (|Z|(f), θ(f)) to obtain the corresponding resonant frequency fr when θ=0, and uses fr as the actual operating frequency.

[0050] Where, |Z|: represents the amplitude of impedance, in ohms (Ω);

[0051] f: frequency in Hz, usually in the range of 20-60kHz in ultrasonic scalpel applications;

[0052] θ: represents the phase angle of impedance, in degrees (°) or radians (rad);

[0053] |Z|(f): represents the functional relationship between impedance amplitude and frequency;

[0054] θ(f): represents the functional relationship between phase and frequency.

[0055] Specifically, the calculation process of the interpolation algorithm in S3 is:

[0056] Step 1: Obtain impedance analyzer swept frequency measurement data

[0057] (1) Obtain measurement data at a series of frequency points within a set frequency range;

[0058] (2) Obtain the impedance amplitude and impedance phase angle value corresponding to each frequency point;

[0059] (3) According to the impedance amplitude and impedance phase angle value corresponding to each frequency point, a data pair is formed: (f1,|Z|1,θ1),(f2,|Z|2,θ2)...(f n ,|Z| n ,θ n ).

[0060] Step 2: Phase Zero Interpolation

[0061] (1) Find the two adjacent frequency points (fa, θa) and (fb, θb) where the phase θ changes from negative to positive.

[0062] (2) Use linear interpolation to calculate the frequency fr corresponding to θ=0: fr=fa+(0-θa)*(fb-fa) / (θb-θa).

[0063] S4, the upper computer controls the switching circuit, turns on switch S2, and turns off switch S1.

[0064] S5. The host computer establishes communication with the host to be calibrated, sets multiple driving frequencies around the actual working frequency fr, and the host to be calibrated sends target frequency driving signals one by one. The signal driving can be current driving.

[0065] S6. The host to be calibrated obtains the voltage and current sampling peak values ​​(Vp, Ip) and the voltage and current phase differences, calculates the impedance at a specific frequency point by |Z|=Vp / Ip, and obtains the second impedance data Z2 ([|Z|(f1),…,|Z|(fr),…,|Z|(fn)], [θ(f1),…,θ(fr),…,θ(fn)]).

[0066] S7. The host computer performs optimal fitting on the first impedance data Z1 and the second impedance data Z2 and calculates a compensation coefficient.

[0067] The compensation process in this embodiment realizes the calibration of the host impedance measurement system through mathematical modeling and optimization algorithm. The compensation process may include amplitude compensation and phase compensation. Taking amplitude compensation as an example, the error model is set and the compensation coefficient is solved to obtain the compensation relationship.

[0068] Step 1: Establish an amplitude error model, where the linear error model is: |Z2|=k1·|Z1|+b1;

[0069] k1 is the proportionality coefficient;

[0070] b1 is the zero point offset.

[0071] Step 2: Solve the compensation coefficient by using an optimization algorithm. As an example, the least square method can be used in this embodiment to solve the compensation coefficient, where the error function is: E1 = Σ(|Z2|(fi)-k1·|Z1|(fi)-b1)2;

[0072] Solve the system of equations:

[0073]

[0074] Step 3: Calculate the amplitude compensation relationship, specifically:

[0075] |Z|compensation=(|Z|original-b1) / k1.

[0076] S8, the host computer uploads the compensation coefficient to the host to be calibrated to update its internal impedance measurement model;

[0077] S9, the host retests the target frequency point to verify whether the measurement error after calibration is less than the set threshold;

[0078] S10. If the measurement error is less than the set threshold, the calibration is judged to be passed, otherwise it is judged to be failed.

[0079] The technical solution of this embodiment realizes a comprehensive verification of the host impedance measurement accuracy through multi-band driving signals and multiple measurements; in addition, by fitting the impedance data and calculating the compensation coefficient, the impedance measurement deviation of the host can be effectively corrected to achieve more accurate impedance calibration.

[0080] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A device for calibrating the impedance measurement value of an ultrasonic soft tissue surgical knife host, characterized in that: include: Host computer, impedance measurement unit, host to be calibrated and standard device; The impedance measurement unit is connected to the host computer and the standard device respectively; The host to be calibrated is connected to the host computer and the standard device respectively.

2. The device according to claim 1, characterized in that The standard device is a standard impedance element with known impedance.

3. The device according to claim 1, characterized in that The impedance measuring unit includes but is not limited to an impedance analyzer or an LCR impedance measuring bridge.

4. A method for calibrating the impedance measurement value of an ultrasonic soft tissue surgical knife host, the method being executed by a host computer, characterized in that: include: Turning on the impedance measurement unit, sending a frequency sweep measurement instruction to the impedance measurement unit according to the set frequency range and obtaining corresponding first impedance data and actual operating frequency; Connecting the host to be calibrated, sending a plurality of driving frequency signals one by one through the host to be calibrated, and calculating the second impedance data according to the sampling values ​​obtained at each driving frequency; Performing optimization fitting and calculating a compensation coefficient according to the first impedance data and the second impedance data; The target frequency point is retested according to the compensation coefficient. If the measurement error after calibration is less than the preset value, the verification passes; otherwise, the verification fails.

5. The method according to claim 4, characterized in that Sending a frequency sweep measurement instruction to the impedance measurement unit according to the set frequency range and obtaining corresponding first impedance data and actual operating frequency includes: Obtain the impedance amplitude and the impedance phase angle corresponding to each frequency point and form a data pair; Obtain two adjacent frequency points corresponding to the phase changing from negative to positive and the phase angles corresponding to the two frequency points; According to the two adjacent frequency points corresponding to the phase changing from negative to positive and the phase angles corresponding to the two frequency points, an interpolation algorithm is used to calculate the frequency corresponding to when the phase angle is 0, and the frequency is used as the actual operating frequency.

6. The method according to claim 5, characterized in that The host to be calibrated sends driving signals of multiple driving frequencies one by one and calculates the second impedance data according to the sampling values ​​obtained at each driving frequency, including: Setting a plurality of driving frequencies around the actual working frequency and sending driving signals of the plurality of driving frequencies one by one through the host to be calibrated; The host to be calibrated obtains the voltage and current sampling peak values ​​and the voltage and current phase differences at each driving frequency, and calculates the impedance value corresponding to each driving frequency point according to the voltage and current sampling peak values, thereby obtaining the second impedance data.

7. The method according to claim 4, characterized in that The step of performing post-optimization fitting and calculating a compensation coefficient according to the first impedance data and the second impedance data comprises: Establishing an error model according to the first impedance value and the second impedance value; The compensation coefficient of the error model is solved by an optimization algorithm and the compensation relationship is calculated.

8. The method according to claim 7, characterized in that The error model includes an amplitude error model and a phase error model.

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