Systems and methods for controlling ultrasonic tools - Patents.com

Abstract

To provide a control system and a control method for reducing the presence of a harmonic signal resulting from driving an ultrasonic surgical tool.SOLUTION: A system 10 and a method for controlling an ultrasonic surgical tool 20 using a console 22 are provided. A first driving signal is applied to the ultrasonic surgical tool 20. Characteristics of a harmonic signal resulting from application of the first driving signal to the ultrasonic surgical tool 20 are acquired. A cancel signal is generated on the basis of the characteristics of the harmonic signal. The first driving signal and the cancel signal are synthesized to generate a second driving signal, which is a sine wave. The second driving signal is applied to the ultrasonic surgical tool 20 so that the presence of the harmonic signal resulting from the application of the second driving signal is reduced as compared to the presence of the harmonic signal resulting from the application of the first driving signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application is the benefit of U.S. Provisional Patent Application No. 62 / 192,838, filed July 15, 2015. The entire disclosure of this U.S. provisional patent application is hereby incorporated by reference. This document shall form part of the Detailed Description.

[0002] The present invention relates generally to systems and methods for controlling ultrasonic surgical tools. More specifically, to reduce the presence of undesired signals caused by the operation of a surgical tool. The present invention relates to a system and method for [Background technology]

[0003] Ultrasonic surgical tools, such as ultrasonic aspirators, typically consist of an ultrasonic transducer and a A handpiece is provided that is connected to the lancer and has a tip that contacts the tissue. A console or generator is connected to the surgical tool and transmits a specific drive signal. The output of the lancet controls a surgical tool. It is used in open or minimally invasive surgical procedures to coagulate blood vessels, etc.

[0004] In many tip-transducer combinations, the transducer The ultrasonic tip is driven by a sinusoidal drive signal with a single frequency component. The oscillating frequency band is designed to operate at a frequency component that has only a specific vibration mode (e.g., a longitudinal mode). It is calculated.

[0005] The vibrating motion of the tip is what is known in the industry as mechanical current. Directly related. When the machine current is in phase with the handpiece voltage, the tip is at resonance. The transducer is driven by a sinusoidal signal with certain frequency components. Therefore, the current to the handpiece is consequently a sine wave with certain frequency components.

[0006] Conventional ultrasonic tip and handpiece combinations inevitably result in high harmonic distortion. Some devices exhibit harmonic signals that can cause malfunctions. The current to the handpiece may exhibit a variable phase shift relative to the voltage to the handpiece. In this system, there is significant harmonic distortion in both the voltage and current to the handpiece. Harmonic signals can cause the voltage and current to the handpiece to introduce additional frequencies such as harmonics. Such high frequency components cause the voltage and current waveforms to become distorted sinusoids. The harmonics cause unwanted vibrations in the tip. Unwanted vibrations can affect the functioning of surgical tools. For example, such unwanted vibrations can increase the stress on the tip. This can increase the temperature and cause unwanted excessive heat in certain locations. Excessive heat can shorten the life of the tip due to fatigue and heating of the surrounding tissue. The system is designed to detect changes in the acoustic properties of the tip due to temperature rise resulting from excessive heat. To overcome the significant loading effects, the device must operate at a higher voltage. This in turn transmits unwanted vibration energy back from the handpiece to the control console. This reduces the performance of the console. Summary of the Invention

[0007] Thus, in accordance with the present invention, the harmonics generated by driving an ultrasonic surgical tool are To reduce the presence of ultrasonic signals, a console for controlling an ultrasonic surgical tool is provided. The console is configured to apply a first drive signal to the ultrasonic surgical tool. The console controls the high frequency generated by applying a first drive signal to the ultrasonic surgical tool. Obtain the characteristics of the harmonic signal. The console performs cancellation based on the characteristics of the harmonic signal. The console generates a second drive signal by canceling the first drive signal. The second drive signal is a sine wave. The presence of harmonic signals is reduced compared to the presence of harmonic signals caused by application of the first drive signal. The console is configured to apply a second drive signal to the ultrasonic surgical tool so as to It is done.

[0008] Also, in accordance with the present invention, harmonic signals generated by driving an ultrasonic surgical tool are A method of controlling an ultrasonic surgical tool to reduce the presence of The method includes the step of driving the ultrasonic surgical tool with a first drive signal. A characteristic of a harmonic signal resulting from the step of driving the tool with the first drive signal is obtained. The method includes generating a cancellation signal based on a characteristic of the harmonic signal. The first drive signal and the cancellation signal are combined to generate a second drive signal. The drive signal is a sine wave. The method includes driving the ultrasonic surgical tool with the second drive signal. The presence of harmonic signals resulting from the first drive signal is The ultrasonic surgical tool is preferably used for ultrasonic surgery, so that the presence of harmonic signals is reduced compared to the presence of harmonic signals caused by ultrasonic surgery. The method includes driving the filter with a second drive signal.

[0009] Further, in accordance with the present invention, an ultrasonic surgical tool is provided that is adapted to reduce the presence of harmonic signals. A method is provided for controlling a harmonic signal, the harmonic signal having a frequency, a phase and an amplitude, the method comprising: Driving the ultrasonic surgical tool with a first drive signal; and obtaining characteristics of harmonic signals resulting from driving the device with a differential signal, and The harmonic has a frequency similar to the number of harmonics, a phase shifted by 180 degrees relative to the phase of the harmonic signal, and The method includes generating a cancellation signal having an amplitude equal to or greater than the ultrasonic signal. and outputting a second drive signal to drive the surgical tool. , is a sine wave and is based on a combination of the first drive signal and the cancellation signal.

[0010] The present system and method advantageously reduces the presence of harmonic signals, thereby reducing the It is possible to reduce harmonic distortion resulting from vibrations in surgical tools. It is possible to reduce the presence of harmonic signals. By reducing the size and weight of the surgical tool, the present system and method The impedance of the combination with the tip, required to maintain the specific vibration displacement of the tip the power and voltage delivered, the heating of the tip, the energy returned to the console, and / or the desired These changes can effectively reduce unwanted (e.g., harmonic) vibration frequencies. This can improve the tissue cutting performance of surgical tools.

[0011] Furthermore, by reducing the adverse effects of harmonic signals, the present system and method Use various types and shapes of ultrasonic tools and tips that exhibit harmonic distortion when The system and method further includes a dual tip design for improved cutting performance. This makes it possible to simultaneously control different resonance modes (e.g., two-mode control).

[0012] As the invention becomes better understood after reading the following description, other features and advantages of the invention will become readily apparent. will be recognized. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a console and an ultrasonic surgical tool according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of components of a console and a surgical tool according to one embodiment of the present invention. [Diagram 3] 13 is a graph illustrating a waveform of a first drive signal output applied from a console to a surgical tool, according to one example. [Figure 4] FIG. 1 illustrates an example of an electromechanical circuit model of a handpiece and tip combination of a surgical tool, according to one example. [Diagram 5] 4 is a graph of the handpiece voltage and current waveforms resulting from the first drive signal of FIG. 3 before application of a harmonic cancellation method; [Figure 6] FIG. 6 is a Fast Fourier Transform of the handpiece voltage waveform of FIG. 5. [Figure 7] FIG. 6 is a Fast Fourier Transform of the handpiece current waveform of FIG. 5. [Figure 8] 5 is a diagram of the electromechanical circuit model of FIG. 4 further illustrating the respective contributions of the fundamental drive frequency and the harmonic frequencies of the harmonic signal resulting from applying the first drive signal to the current in each branch of the circuit. [Figure 9] 4 is a flow diagram of a method for controlling an ultrasonic surgical tool to reduce the presence of harmonic signals resulting from driving the ultrasonic surgical tool with the first drive signal of FIG. 3, in accordance with an embodiment of the present invention. [Figure 10] 1 is a graph of a waveform of a Fast Fourier Transform of a handpiece current showing fundamental and harmonic frequency components. [Figure 11]4 is a graph of a waveform of a handpiece current showing fundamental and harmonic frequency components. [Figure 12] 12 is a graph showing the waveform of the fundamental frequency component of the handpiece current of FIG. 11 separated. [Figure 13] 12 is a graph showing the waveform of the harmonic frequency components of the handpiece current of FIG. 11 separated. [Figure 14] 14 is a graph of a waveform of a cancellation signal configured to reduce the harmonic frequency components of FIG. 13. [Figure 15] 15 is a graph showing a waveform of the output of a second drive signal applied from a console, generated based on a combination of the fundamental frequency component (first drive signal) of FIG. 12 and the cancellation signal of FIG. 14. [Figure 16] FIG. 19 is a Fast Fourier Transform of the handpiece voltage waveform of FIG. 18. [Figure 17] FIG. 19 is a Fast Fourier Transform of the handpiece current waveform of FIG. 18. [Figure 18] 16 is a graph of the handpiece voltage and current waveforms resulting from the second drive signal of FIG. 15 after applying a harmonic cancellation method. [Figure 19] 1 is a table demonstrating the beneficial effect of the method of the present invention on key parameters controlling a handpiece and tip combination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] I. System Overview Referring to the drawings, like numerals indicate like or corresponding parts throughout the several views. to reduce the presence of harmonic signals resulting from driving the ultrasonic surgical tool 20. To this end, aspects of the system 10 and method 12 for controlling an ultrasonic surgical tool 20 are fully described. It is shown through the body.

[0015] As shown in FIG. 1, the system 10 includes an ultrasonic surgical tool 20 and an ultrasonic surgical tool 22. The surgical tool 20 is connected to the console 22. 2. Examples of surgical tools 20 include, but are not limited to, medical devices. These include, but are not limited to, ultrasonic aspirators, ultrasonic sealers, ultrasonic cutters, and the like.

[0016] The surgical tool 20 includes a handpiece 21. As shown in FIG. The transducer 24 is housed within the housing 22. The transducer 24 functions to receive electrical energy. Any suitable element or configuration, such as a piezoelectric ceramic element, suitable for converting mechanical energy into The surgical tool 20 may include a surgical element. Examples of tissue engagement include tissue cutting and The tip 26 may be connected to the transducer 24. can.

[0017] The surgical tool 20 may utilize a variety of interchangeable tips 26. can be permanently or removably fixed to the handpiece 21. The tip 26 is Any suitable function and configuration may be used, for example, a tip for soft tissue resection and a tip for fine bone resection. Examples of preferred tips 26 include: including, but not limited to, Stryker™ Straight™ for soft tissue, S Stryker(TM) Barracuda(TM) and Stryker(TM) for hard tissue Trademarks) Claw(trademark), Stryker(trademark) Knife(trademark), Stryk Includes Payner(trademark) and Payner(trademark).

[0018] In one embodiment, the console 22 includes a memory 28, a controller 30, and an amplifier. 32. Memory 28 stores relevant data for controlling surgical tool 20. The memory 28 may be a non-volatile memory, a ROM, an EEPROM, a RAM, or a The memory may be any suitable type of memory, such as M, flash memory, etc. 22 may include any suitable control circuitry stored in memory 28 to aid in the control of surgical tool 20. The controller 30 may include a memory 28. The controller 30 is connected to a single The controller 30 may include one or more processors. The amplifier 32 is in communication with the output of the power supply 32. The amplifier 32 is in communication with the power supply 32 for output. In one embodiment, the amplifier 32 is a linear amplifier. It is.

[0019] The controller 30 includes a sampling module 34, a signal generating unit 36, and a signal synthesizing unit 37. 2, the sampling module 34, the signal generating unit 3 6 and the signal synthesis unit 38 are part of the controller 30 or are integrated with the controller 30. Alternatively, the sampling module 34, the signal generating unit 36 ​​and the signal synthesis unit 37 are configured as a single unit. Any one or combination of the units 38 may be physically independent of the controller 30. The controller 30 may be physically external to the controller 30 so that the In some cases, any one of the sampling module 34, the signal generating unit 36, and the signal combining unit 38 may be Either of them may be integrated into the same component or may be implemented by the same software. The sampling module 34 may be combined to perform a fast Fourier transform. The fast Fourier transform (FFT) module 37 can communicate with The module 37 may be included.

[0020] A sampling module 34, a signal generating section 36, an FFT module 37 and a signal synthesizing section Any of the above-mentioned programs may include executable instructions. The executable instructions may include one or more The sample is stored in the memory 28 of the console 22 for execution by the processor. The functions of the ring module 34, the signal generating section 36, the FFT module 37 and the signal synthesizing section 38 are The functions are explained in detail below.

[0021] II. First Drive Signal and Harmonic Signal The console 22 provides a transducer for the ultrasonic surgical tool 20. The transducer 24 is configured to apply a first drive signal 40 to the transducer 24. 4 converts the electrical energy of the first drive signal 40 into mechanical energy. The first drive signal 40 is output from an amplifier 32 in the console 22, which amplifies the first drive signal 40. The first drive signal 40 is a low voltage. For example, the voltage of the first drive signal 40 is 0 VA. C to 100VAC, more specifically, 0VAC to 10VAC, The power supply voltage is 0 VAC to 5 VAC. The amplifier 32 supplies the required In response to this, the voltage of the first drive signal 40 is amplified to 1000 VAC. The first console 22 is an optional device that allows an operator to selectively control the first drive signal 40. The control may include any suitable switch or button.

[0022] FIG. 3 shows an example of a first drive signal 40 for one particular handpiece 21. The handpiece 21 has a sharp angle joint and a minute straight tip. The micro straight tip 26 has a function of 80 mA. The actuator is driven in air by a 25.5 kHz voltage sine wave drive signal. Specifically, Figure 3 shows the voltage output of the first drive signal 40. The first drive signal 40 has a sinusoidal waveform. In other words, the first drive signal 40 has a waveform that exhibits smooth, repetitive vibrations. Therefore, the first drive signal 40 is not a pulse wave or a square wave. The sinusoidal nature of the waveform of 40 is important to impart ultrasonic vibrations within the tip 26. The sinusoidal waveform of the signal 40 has a wavelength λ of the first drive signal 40. 1 It contains frequency components related to The frequency component is a component of the fundamental (first harmonic) drive frequency 41. This component may also be known as the desired resonant frequency. The component of the fundamental driving frequency 41 is 25.5 kHz. It can be any suitable frequency, including frequencies in the range of 5 kHz to 55 kHz. Those skilled in the art will recognize that the first drive signal 40 has a phase "P1" and an amplitude "a 1 " The console 22 further includes a signal generating unit 36 ​​for generating a first drive signal 40. The device is configured to:

[0023] The first drive signal 40 includes several characteristics. The characteristics of the first drive signal 40 generally include: Any characteristic of the first drive signal 40 may be measured in the time domain or The characteristics can be based on the frequency domain. For example, the characteristics in the time domain as shown in FIG. The first drive signal 40 has a characteristic of having a wavelength λ 1 , phase "P1" and amplitude "a 1 " A small number of As shown in Figures 6 and 7, the following frequency domains can be included: For example, the characteristics of the first drive signal 40 include the frequency, magnitude and For example, the frequency may include at least one of the fundamental driving frequency 4 The characteristics of the first drive signal 40 may be predetermined or may be known. Alternatively, the characteristics of the first drive signal 40 may be measured. For example, the characteristics of the first drive signal 40 may be determined by the characteristics of the first drive signal 40 as described below. The first drive signal may be derived from a measurement of a current or voltage associated with applying the first drive signal to the first drive circuit. 40 arbitrary characteristics can be individually selected from the time domain parameters and the frequency domain parameters, or Those skilled in the art will recognize that can be derived combinatorially.

[0024] FIG. 4 shows an example of an electromechanical circuit model of the combination of the handpiece 21 and the tip portion 26. In FIG. S is the output drive voltage (voltage source) from the console 22. Below, the output drive voltage is the handpiece voltage V HP In Figure 4, R S Hako is the series resistance of the console. R S The current flowing through is the source current i S and in the following Handpiece current i HP Also called handpiece current i HP The Handpiece 21 The impedance of the handpiece 21 can be determined by the impedance of the The impedance can be derived from one or more characteristics. For example, the impedance can be determined from the negative the load, the acoustic properties of the handpiece 21, the acoustic properties of the tissue to be ablated, the acoustic properties of the transducer 24 This is due to the characteristics, vibration of the handpiece 21, etc.

[0025] As shown in Figure 4, the static handpiece capacitance is C o and static capacity Citans C o The current flowing through i co The vibration resonance mode is m , L m and C m where i m represents the desired machine current. The desired machine current i m Ha, ha The vibration motion of the tip 26 is induced by the load on the end piece 21. current i m The vibrational displacement of the tip 26 is directly related to the mechanical current i m increases The tip 26 is connected to the desired machine current i m is the handpiece voltage V HP In phase with When

[0026] The model in Figure 4 is the standard Butterworth-Van Dyke model. It is based on the model, but is improved by incorporating a common component X and its effect on the model. The general component X is a surgical tool 20, more specifically a handpiece 2 1 and tip 26 to generate a harmonic signal 44 The harmonic signal 44 is a theoretical component of the fundamental driving frequency 41. Any higher harmonic, such as the second, third or fourth harmonic, or any of its The harmonic signals 44 are a source of harmonic distortion and therefore may include any combination of In the following, the frequency of the harmonic signal 44 is referred to as the harmonic frequency. The harmonic signals 44 are necessarily the components of the handpiece 21 and tip section 26. In some cases, the harmonic signal 44 may be generated based on a particular combination. , does not appear until a minimum threshold displacement of tip 26 has occurred. Such behavior is known as nonlinear behavior. It is considered that the current i flows through a general component X. x represents the undesired machine current. In some versions of the model, the common component X is the desired machine current i m By or the desired machine current i m may be an oscillating current source related to

[0027] FIG. 5 shows a harmonics cancellation method 12 of the present invention before applying the harmonics cancellation method 12 described herein. Dopous current i HP and handpiece voltage V HP The waveform of the handpiece current i HP and Handpiece voltage V HP 1 and 2. An exemplary effect of a harmonic signal 44 on the waveform of the first Since the drive signal 40 is sinusoidal and has certain signal frequency components, the handpiece current i H P and handpiece voltage V HP The resulting signal is sinusoidal and has certain frequency components. In this case, the fundamental driving frequency 41 component is accompanied by a harmonic frequency 43 component, so that the handle Dopous current i HP The waveform of the handpiece voltage V HP shows a variable phase shift φ with respect to Handpiece current i HP and handpiece voltage VHP indicates multiple frequency components The waveform is not a pure sine wave. HP and handpiece voltage V HP will vary depending, among other things, on the particular tip 26 utilized.

[0028] 6 and 7 show the handpiece voltage V HP and handpiece current i HP Waveform The fast Fourier analysis of the observed It identifies the frequency (or frequencies) that cause the most distortion. In this example, the FFT analysis identifies the fundamental driving frequency 41 (i.e., 25.5 kHz z) is accompanied by an additional harmonic frequency 43 component (e.g., 51 kHz) of the harmonic signal 44. It is clear that harmonic signals 44 are the source of the resulting harmonic distortion. Handpiece voltage V HP In this case, the component of the harmonic frequency 43 is the component of the fundamental driving frequency 41. The handpiece current i HP If , the harmonic frequency The component of 43 has a magnitude that is more than 90% of the magnitude of the component of the fundamental drive frequency 41. It should be understood that Figures 6 and 7 show an example of a component at harmonic frequency 43. Therefore, the harmonic frequency 43 components may differ from the harmonic frequencies of FIGS. They may have different sizes.

[0029] Further analysis of the data reveals that the handpiece voltage V HP and handpiece current i HP Waveform of It is clear that the phase angle θ between the harmonic signals 44 in is 103 degrees. θ is greater than 90 degrees, which gives a negative power factor (console is 51k Instead of generating power at 100 Hz, the combination of handpiece 21 and tip 26 It is shown that the 25.5kHz vibration produces power at 51kHz. Due to the nonlinear vibration behavior of the combination of end piece 21 and tip 26, The 51 kHz vibrations move the piezoelectric elements in the transducer 24, which This converts a portion of the mechanical energy into electrical energy at 51 kHz, i.e., harmonic Converted into a wave frequency 43 component.

[0030] FIG. 8 shows the components and harmonics of the fundamental driving frequency 41 for the current in each branch of the circuit of FIG. The contribution of each of the components at frequency 43 is shown. This contribution is C o For impedance of R m The assumption that the value of R m , L m , C m The series impedance of the harmonic frequency 4 This is based on the assumption that the impedance of the 3rd component is relatively high. The fundamental drive frequency 41 and the harmonic frequency 43 are respectively current i HP The fundamental driving frequency 41 component is the static capacitance C o To Current flowing i co and the desired machine current i m In contrast, the harmonic frequencies The component of 43 is the current flowing through the static capacitance i co and the desired machine current i m Substantially Moreover, the undesirable machine current i x Regarding the fundamental driving frequency 41 component does not contribute substantially, whereas the component at harmonic frequency 43 contributes significantly. According to this model, the handpiece current i HP The harmonic signals 44 present in the Undesirable mechanical current i flowing through component X x This is directly related to the existence of

[0031] III. Reduction of the second drive signal and harmonic signals The system 10 and method 12 reduce the presence of the harmonic signals 44 described above. As shown in FIG. 9, the method 12 includes, in step 200, providing a first actuator to the ultrasonic tool 20. In step 202, the ultrasonic surgical instrument may include applying a signal 40. At least one of the harmonic signals 44 generated by applying the first drive signal 40 to the tool 20 In step 206, a characteristic of the harmonic signal 44 is obtained. In step 208, the console 22 generates the cancel signal 70. combines the first drive signal 40 and the cancellation signal 70 to generate the second drive signal 80 The second drive signal 80 is a sine wave. In step 210, the console 22 A second drive signal 80 is applied to the ultrasonic surgical tool 20. A second drive signal 50 is applied The presence of harmonic signals 44 resulting from the application of the first drive signal 40 The harmonic signals 44 are reduced compared to the presence of the harmonic signals 44. Explain in detail.

[0032] The console 22 executes step 202 to obtain the characteristics of the harmonic signal 44. The characteristics of the harmonic signal 44 can be based on the time domain or the frequency domain. For example, in the time domain, the harmonic signal 44 is characterized by a wavelength λ2 , phase "P2" and amplitude "a 2 " (see FIG. 13). In terms of the frequency domain, As shown in FIGS. 6 and 7, which will be described below, for example, the characteristics of the harmonic signal 44 are This may include at least one of the frequency, magnitude, and phase of the signal 44. For example, The frequency of the harmonic signal 44 is a component of the harmonic frequency 43, more specifically, the second harmonic Any characteristic of the harmonic signal 44 can be calculated in the time domain and Those skilled in the art will recognize that these may be obtained individually or in combination from the frequency domain.

[0033] As mentioned above, the characteristics of the first drive signal 40 may be predetermined, or Therefore, the characteristics of the first drive signal 40 and the characteristics of the harmonic signal 44 may be known. The sex can be determined at another time. Alternatively, or in addition, the first drive If the characteristics of the motion signal 40 are unknown, the console 22 executes step 202 to The characteristics of the first drive signal 40 can be further obtained. In other words, the first drive signal The characteristics of the harmonic signal 40 and the characteristics of the harmonic signal 44 may be determined simultaneously or at separate times. can be done.

[0034] In one embodiment, the console 22 is in part responsible for applying the first drive signal 40. Obtaining characteristics of the harmonic signal 44 by generating current and voltage samples corresponding to the More specifically, the voltage sample is the handpiece voltage V HP Based on this, the current samples are Endpiece current i HP The characteristics of the harmonic signal 44 are related to the waveform of the harmonic signal 44. Therefore, the characteristics of the harmonic signal 44 are present in the current and voltage samples. It can be extracted from the sample.

[0035] In one example, the console 22 measures or detects a known static capacitance value C o The characteristics of the harmonic signal 44 are obtained by starting from the fundamental of the first drive signal 40. The magnitude and phase of both the voltage and current for the frequency 41 component are predetermined. or is known and can be accessed from memory 28. Once this information is known, The console 22 controls the handpiece 21 and tip 26 to transmit a fundamental frequency 41 component (e.g. , 25.5 kHz) to be set to a relatively low vibration level. The console 22 uses a tracking algorithm that monitors resonances. By this, the handpiece 21 and the tip 26 are driven at the fundamental frequency 41 component. The tracking algorithm is executed by the controller 30. The controller 30 controls the handpiece 21 and the tip portion 26 in response to the vibration. These resonances are constantly measured and / or calculated. The tracking algorithm If the measured resonance deviates from the desired resonance, make appropriate adjustments to achieve the designed resonance. The tracking algorithm is configured to continuously monitor the movement of the surgical tool 20. Any suitable tracking algorithm may be implemented. Those skilled in the art will recognize this.

[0036] The console 22 uses the sampling module 34 to apply a first drive signal 40. The console 22 acquires samples of the current and voltage resulting from, for example, As shown in FIG. 5 above, the handpiece current i HP and handpiece voltage V HP The current and voltage samples are obtained by sampling the The control 22 monitors and / or samples the impedance of the handpiece 21 and the tip 26. The console 22 can sample the analog input and derive current and voltage samples. Convert the current and voltage samples for further analysis using a log / digital conversion device or similar. The console 22 samples the first drive signal 40 and / or the harmonic signal 44. There is no need to generate a waveform like that shown in Figure 5 to measure or characterize it. Those skilled in the art will appreciate that, alternatively, the sub-sequence may be based on non-visual data, such as binary values. The console 22 can generate and analyze a first sample to the surgical tool 20. The samples may be taken during or after application of the drive signal 40. The sample is accessed by the controller 30 at any suitable time after the sample is acquired. The information may be stored in memory 28 for easy access.

[0037] The console 22 analyzes the samples to obtain characteristics of the harmonic signal 44. By obtaining the characteristic of No. 44, the console 22 determines the handpiece current i HP and Handpiece voltage V HP (e.g., at the second harmonic frequency 43) In one example, the console 22 uses FFT analysis techniques to measure the , to obtain the characteristics of the harmonic signal 44. Here, the console 22, more specifically, the FFT Module 37 performs an FFT of the current and voltage samples. Current and voltage samples can be acquired and processed in real time during the application of the drive signal. Cut.

[0038] Figure 10 shows the sampled handpiece current i HP Here is an example of FFT of 25. The 5 kHz and 51 kHz frequency components have large amplitudes relative to other parts of the spectrum. It is shown that the console 22, based on the samples, has a significantly smaller measured distortion. If it is determined that the vibration is too large, the console 22 will not operate the machine until unacceptable harmonic vibrations are produced. current i m Now the console 22 can continue to increase the harmonic frequency 43 The amplitude of the component (second harmonic) of the fundamental driving frequency 41, i.e., 25.5 kHz, The machine current i m Increase the

[0039] The characteristics of the harmonic signal 44 can be further understood based on FIGS. 6 and 7 above. These figures show graphs that represent the results of performing an FFT on the example described. 6 and 7 will not be repeated for the sake of brevity. The FFT produces data that represent the transformation. Therefore, in order to obtain the characteristics of the harmonic signal 44, the following steps are performed using the Those skilled in the art will appreciate that it is not necessary to generate a graph such as that shown in In one particular embodiment, the FFT of the current and voltage waveforms determines whether the second drive signal 80 is active. The FFT is performed to generate a statistically significant number of samples, and therefore is not used solely for diagnostic purposes. do not have.

[0040] To determine the characteristics of the harmonic signal 44, the console 22 further The characteristics of the harmonic signal 44 can be compared to the characteristics of the harmonic signal 44. obtains the difference between the phase P1 of the first drive signal 40 and the phase P2 of the harmonic signal 44. The console 22 detects the handpiece voltage V at the fundamental frequency 41. HP and Handpiece current i at harmonic frequency 43 HP Calculate the phase difference between the Thus, the console 22 generates a handpiece voltage V at the first harmonic frequency. HP Against The handpiece current i at the second harmonic frequency HP Find the phase of the first harmonic frequency. Handpiece voltage at wave number V HP Handpiece at the second harmonic frequency current i HP The phase of is also known as the phase angle.

[0041] To do this, the console 22 supplies the handpiece voltage V HP and handpiece current i HP For at least one of the above, the harmonic frequency 43 component is separated from the fundamental frequency 41 component. As an example, FIG. 11 shows the handpiece current i HP Similar to Samp Ringed handpiece current i HP The sampled handpiece current i H P The waveform of has two frequency components, namely, a fundamental frequency 41 component and a harmonic frequency 43 Contains the ingredients.

[0042] Figure 12 shows the handpiece voltage V HPThe waveform of the fundamental frequency 41 component extracted from In particular, in this example, the waveform of FIG. 12 is the source waveform of the first drive signal 40 of FIG. That is, the waveform including the separated fundamental frequency 41 component is the first drive signal of the first drive signal 40 before the harmonic signal 44 resulting from application of 40 is produced. It is the same as the source waveform.

[0043] FIG. 13 shows the handpiece current i HP The harmonic frequency 43 component extracted from Thus, FIG. 3 shows the waveforms resulting from application of the first drive signal 40. 1 shows an isolated harmonic signal 44, which is , the wavelength λ of the harmonic signal 44 2 It has a sinusoidal waveform that contains frequency components related to harmonics. The wave signal 44 has a phase "P2" and an amplitude "a 2 " It also has.

[0044] In one embodiment, the console 22 calculates the phase angle to determine the fundamental frequency 4 Handpiece voltage V at component 1 HP The phase of the hand-piston at harmonic frequency 43 Source current i HP In this example, the handpiece voltage V HP and Hand Piece current i HP Using the specific frequency, phase and amplitude of Calculate the phase angle from the formula:

number

[0045] Here, the console 22 supplies the handpiece current i HP Harmonic frequency 44 (51.5k Hz) is the handpiece voltage V at the fundamental frequency 41 (25.5 kHz) HP To It is judged that the phase is shifted by -90 degrees. It is judged that the phase is shifted by -90 degrees. The console 22 can then adjust the cancellation signal 70. Mainly, harmonics To mathematically cancel the amplitude of signal 44, the phase of cancellation signal 70 is The cancellation signal 70 is shifted 180 degrees in phase with the first drive signal 44. 0. The current of the cancellation signal 70 is necessarily equal to the voltage of the cancellation signal 70. The waveform of the harmonic current is shifted by 90 degrees from the first drive signal 40. In order to cancel the harmonic signal 44 by the cancellation signal 70, the cancellation signal 7 0 is shifted by 90 (-90) degrees in the opposite direction relative to the first drive signal 40. Thus, the phase of the cancellation signal 70 is shifted 180 degrees relative to the phase of the harmonic signal 44. do.

[0046] The method 12, in step 206, comprises: 22. The cancellation signal 70 is generated based on the harmonic 44, thereby minimizing the effects of the harmonic signal 44. In one embodiment, the cancellation signal 70 reduces the presence of the harmonic signal 44. In practice, the cancellation signal 70 is the unwanted machine current i x Based on one or more characteristics of. Therefore, cancellation Signal 70 represents the unwanted machine current i x This minimizes the presence of harmonic signals 44 in the Thus, in the example described herein, the cancellation signal 70 is the second harmonic Unwanted machine current i at frequency 43 x This minimizes the Source current i HP The console 22 uses a signal generator 36 to , and generates a cancellation signal 70. Data related to the generated cancellation signal 70 is stored in a memory. It can be stored in memory 28.

[0047] FIG. 14 shows an example of the waveform of the cancellation signal 70. As shown in the figure, No. 70 is the wavelength λ of the cancellation signal 70 3 has a sinusoidal waveform that contains frequency components related to The cancellation signal 70 also has a phase "P3" and an amplitude "a 3 " It also has.

[0048] In one embodiment, the console 22 performs a cancel based on the frequency of the harmonic signal 44. For example, the frequency of the cancellation signal 70 is set to maximize the harmonic signal 44. More specifically, the console 22 can be configured to cancel the The cancellation signal 70 is adjusted so that the frequency of the cancellation signal 70 is similar to the frequency of the harmonic signal 44. In this case, the wavelength λ of the cancellation signal 70 in FIG. 3 is the harmonic signal in Figure 13. 44 wavelengths λ 2 More specifically, in this example, the cancellation signal 70 is The frequency is set to 51 kHz, which is the frequency determined for the harmonic signal 44. By having the same frequency as the harmonic signal 44, the cancellation signal 70 has the fundamental frequency 4 without affecting the first component or otherwise introducing other undesirable frequencies. In order to reduce the effect of the harmonic frequency 43 without The frequency of the cancellation signal 70 is exactly the same as the harmonic frequency 43. Those skilled in the art will recognize that, although not equal, they may be similar. The frequency of the cell signal 70 is set to 400 Hz, 500 Hz, 1000 Hz, 1500 Hz, 2000 Hz, 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, 7000 Hz, 8000 Hz, 9000 Hz, 10000 Hz, 11000 Hz, 12 3. In another example, the cancellation signal The frequency of 70 may be 1 kHz greater or less than the harmonic frequency 43 .

[0049] The cancellation signal 70 is further configured such that the phase P3 of the cancellation signal 70 is equal to the phase P In one embodiment, the can be made to be a shifted version of the can The phase P3 of the cell signal 70 is determined to minimize the harmonic signal 44. , the phase P3 of the cancellation signal 70 is shifted by 180 degrees relative to the phase P2 of the harmonic signal 44. Therefore, the phase P3 of the cancellation signal 70 in FIG. 14 is the same as the phase P4 of the harmonic signal 4 in FIG. Phase P3 is shifted by half a period with respect to phase P2 of harmonic signal 44. By shifting the amplitude of the cancellation signal 70 by 180 degrees, 3 However, as shown in Figure 14 As a result, the amplitude a of the harmonic signal 44 2 Therefore, the harmonics due to the cancellation signal 70 The cancellation effect of the signal 44 is maximized. Those skilled in the art will appreciate that the phase P1 of the first embodiment may be shifted by an angle other than 180 degrees relative to the phase P2 of the second embodiment. It will be appreciated that, for example, the phase P3 of the cancellation signal 70 may be 540 degrees, −180 degrees, etc. It may be shifted by any positive or negative odd multiple of 180 degrees.

[0050] The cancellation signal 70 has an amplitude a 3 is the amplitude a of the harmonic signal 44 2 To In one embodiment, the ion exchange coefficient can be further designed to be adjusted for the ion exchange coefficient as shown in FIG. , the amplitude a of the cancellation signal 70 3 is the amplitude a of the harmonic signal 44 2 Cancellation notice Amplitude of No. 70 a 3 The amplitude of the harmonic signal 44 is a 2 By equating it to The effect of canceling the harmonic signal 44 by the cancellation signal 70 is maximized. Amplitude of 70 a 3 is the amplitude a of the harmonic signal 44 as shown in FIG. 2 is equal to and vice versa (based on phase shift).

[0051] Alternatively, if desired, the cancellation signal 70 may be further adjusted to have an amplitude a 3 is the amplitude a of the harmonic signal 44 2 Design it to be larger or smaller than For example, in a certain case, the amplitude a of the cancellation signal 70 3 is the amplitude of the harmonic signal 44 width a 2 According to various other levels not specifically described herein. The amplitude of the cancellation signal 70 is a 3 The amplitude of the harmonic signal 44 is a 2 In some cases, it can be set in relation to Those skilled in the art will recognize that in some cases, the position of the cancellation signal 70 may be Phase A 3 can be designed to minimize harmonic signals 44.

[0052] In another embodiment, the amplitude a of the cancellation signal 70 3is the effect of the canceller on the harmonic signal 44. Based on an amplitude adjustment algorithm designed to monitor the effect of amplitude changes on the cell signal 70. For example, the amplitude adjustment algorithm is 3 Starting from , until the component of harmonic frequency 43 is minimized, amplitude a 3 It is possible to increase The source 22 uses a feedback loop to monitor the effect of the harmonic frequency 43 on the content It is possible.

[0053] The console 22 determines at least one or a combination of any of the characteristics of the harmonic signal 44. Those skilled in the art will recognize that the cancellation signal 70 can be generated based on a combination. For example, the cancellation signal 70 may be a signal having a frequency and amplitude a 2 Based on, but with high The cancellation signal 7 may be generated without being based on the phase P2 of the wave signal 44. 0 is based on the frequency and phase P2 of the harmonic signal 44, but the amplitude a 2 Based on In designing the cancellation signal 70, the harmonic In situations where some characteristics of the signal 44 are not taken into account, the cancellation signal 70 may, for example, be The signal may be generated based on a preset or default frequency, phase or amplitude.

[0054] In step 208, the console 22 receives the first drive signal 40 and the cancel signal 70. and generate the second drive signal 80. In other words, the console 22 The second drive signal is generated by combining the cell signal 70 with the original or source first drive signal 40. The console 22 generates a dynamic signal 80 (resulting in no harmonic signal 44). The two signals are added together using a combiner 38. The console 22 stores the , and accesses information about the first drive signal 40 and the cancellation signal 70. can.

[0055] FIG. 15 shows the output drive voltage of the second drive signal 80 for the example described herein. As with the first drive signal 40, the second drive signal 80 is adapted to control the appropriate ultrasonic operation of the surgical tool 20. It is sinusoidal to aid in wave action.

[0056] The cancellation signal 70 is the handpiece voltage V HP In this case, the first 2 The output drive voltage of the drive signal 80 is the modified handpiece voltage V HP’ To understand that That is, the original handpiece voltage V of the first drive signal 40 HP Changes depending on the relationship The second drive signal 80 in FIG. 15 is a 25.5 kHz signal similar to the first drive signal 40 (FIG. 12). and a 51 kHz cancellation signal 70 (FIG. 14). The voltage output of signal 80 is both a 25.5 kHz drive signal and a 51 kHz cancellation signal. In other words, the cancellation signal 70 is HP Fundamental frequency of 41 In order to obtain a high frequency component, a second frequency component 77 is provided. A second harmonic having a phase shift of 180 degrees out of phase with respect to the component at harmonic frequency 43. 43 component, thereby effectively minimizing the harmonic frequency 43 component. .

[0057] The console 22, and more specifically the signal synthesis unit 38, uses mathematical operations to generate the first drive signal. 40 and the cancellation signal 70. In the example described here, the signal The combiner 38 combines the signals using the following equation [2].

number

[0058] More specifically, the frequency and phase of the first drive signal 40 and the cancellation signal 70 When the amplitude and the amplitude are input, equation [2] can be expressed as follows:

number

[0059] In step 210, the console 22 transmits the second drive signal 80 to the ultrasonic surgical tool 2. Similar to the first drive signal 40, the console 22 applies the ultrasonic surgical tool 2 0, and more specifically, applies a second drive signal 40 to the transducer 24. That is, the amplifier 32 amplifies the voltage of the second drive signal 80, and the transducer 24 outputs the second drive signal 80. The electrical energy of the signal 80 is converted into mechanical energy.

[0060] By introducing the cancellation signal 70, the second drive signal 80 cancels out the harmonic signal 44. The second drive signal 80 is specifically designed to counteract undesirable vibratory motion. The transducer 24 is driven to produce a force that opposes the force. This opposing force is undesirable. In fact, the vibration caused by applying the second drive signal 80 is effectively cancelled. The presence of the harmonic signal 44 is caused by applying the first drive signal 40. More specifically, the desirably No machine current i xIn other words, the presence of harmonic signals 44 in the In the example described above, the unwanted mechanical current at the second harmonic frequency 43 is Flow x is minimized after applying the second drive signal 80, thereby reducing the handpiece current i HP Harmonic distortion in the signal is minimized.

[0061] In some embodiments, the console 22 may be configured to cancel during operation of the surgical tool 20. For example, the console 22 may be configured to generate "n" repetitive loop signals 70. (first, second, third drive signal, etc.) and apply each "nth" drive signal. The characteristics of the harmonic signals (if any) that arise from the The controller 22 tracks harmonic distortion throughout the use of the tip 26 or throughout the surgical procedure. "n" cancellation signals can be provided. In such a case, each "nth" drive signal The nth cancellation signal, each nth cancellation signal, and each resulting harmonic signal are different from each other. In some embodiments, the harmonic signal 44 is at an appropriate level to allow the console to The console 22 continues this process until the controller 22 determines that, for example, The harmonic frequency 44 is less than a predetermined threshold (e.g., the magnitude of the harmonic frequency 43 component is less than the fundamental frequency 5% of the magnitude of the component of 41) or until the console 22 determines that the harmonic signal The console 22 may continue this process until the number 44 is removed.

[0062] The console 22 may include a plurality of inputs for generating the cancellation signal 70 or each "nth" cancellation signal. To this end, the level of the harmonic signal 44 can be measured and tracked using any suitable method. In one example, the console 22 can use a known value for Co to current i HP Calculate the harmonic frequency 43 in the . When it is minimized to near 0, it is Current flowing i C0 The harmonic frequency 43 component of the current)i x Represents.

[0063] FIG. 15 shows the modified handpiece current i after applying the harmonic cancellation method 12. HP’ and handpiece voltage V HP’ The waveforms in Fig. 15 are compared with those in Fig. 5. The effect of the harmonic signal 44 on the After that, the fundamental driving frequency 41 component is significantly affected by the harmonic frequency 43 component. Therefore, the handpiece current i HP’ The waveform of the handpiece voltage V HP’ Against The minimum phase shift φ is shown. Furthermore, the handpiece current i HP’ and handpiece voltage V HP’ Since it mainly shows only one frequency component, namely the fundamental driving frequency 41 component, The waveform is substantially sinusoidal.

[0064] 16 and 17 show the change in the handpiece voltage V HP’ and handpiece current i HP’ The fast Fourier analysis of each waveform is shown in Fig. 6 and Fig. 7. The FFT analysis shows that the fundamental driving frequency 41 (i.e., 25.5 kHz) is a harmonic signal 4 4 harmonic frequency 43 components (e.g., 51 kHz) are virtually unaffected. In addition, the magnitude of the harmonic frequency 43 component at 51 kHz was reduced. The handpiece voltage V HP’ In this case, the magnitude of the harmonic frequency 43 component is 1 is 25% of the magnitude of the harmonic frequency 43 component generated from the drive signal 40. current i HP’ In this case, the magnitude of the component at harmonic frequency 43 is substantially eliminated.

[0065] Furthermore, the machine current i m is related to the mechanical displacement of the tip 26, so the handpiece current i HP Minimizing distortion in the handpiece voltage V HP Minimize distortion within the Therefore, the handpiece current i HP More than handpiece Voltage V HP Although the distortion in is larger, both waveforms show a significant improvement at the 51kHz frequency. Shows.

[0066] Furthermore, by suppressing the harmonic frequency 43 components using method 12, the tip 26 In this specification, the present invention provides an opportunity to implement nonlinear and bi-modal control. In the example given above, the nonlinear behavior is such that the surgical tool 20 is driven by a component of the fundamental drive frequency 41. When driven by a 25.5 kHz voltage sine wave, the handpiece 21 and the tip portion 26 The combination behaves as if it oscillates at 51 kHz, the component of harmonic frequency 43. By suppressing the harmonic frequency 43 component, the tip 26 can be dynamically controlled to achieve a higher level of accuracy than in the past. It can give surgeons better access to areas of the body that were previously difficult to reach. In other words, by reducing the adverse effects of the components of the harmonic signal 41, the system 10 and method Method 12 is used with various types and shapes of ultrasonic tools and The system 10 and method 12 further enhance cutting performance. In order to achieve this, two different resonance modes of the tip 26 can be controlled simultaneously (e.g., two-mode control). Furthermore, the cancellation signal 70 reduces the harmonic signal 44, but The signal 70 includes additional frequency components in order to achieve bi-modal control of the tool 20. It may also be configured to provide this in the drive signal 80.

[0067] FIG. 19 shows a number of important parameters that control the handpiece 21 and tip 26 combination. A table is provided showing significant improvements in the parameters measured during application of the second drive signal 80. Handpiece voltage V HP’ and handpiece current i HP’ is the application of the first drive signal 40 The handpiece voltage V measured during HP and handpiece current i HP Compared to 22% Similarly, the handpiece pressure measured during application of the second drive signal 80 is reduced by 23%. The impedance of the handle 21 and the tip 26 is measured during application of the first drive signal 40. The impedance of the end piece 21 and tip 26 is reduced by 23%. As a result, the hand-pickup frequency at 51 kHz component measured during application of the second drive signal 80 was Source current i HP’ The relative magnitude of the first drive signal 40 is substantially eliminated. In addition, in this example, the second drive signal is reduced by 98.8% compared to when the second drive signal is applied. Unwanted machine current i present at 51 kHz after application of No. 80 x was 3.4mA This is in accordance with the desired current present at 51 kHz after application of the first drive signal 40, which was 83 mA. Non-linear mechanical current i x This significantly reduces unwanted vibrations. show.

[0068] These results demonstrate that system 10 and method 12 effectively reduce the presence of harmonic signals 44. , thereby clearly demonstrating the reduction of harmonic distortion resulting from vibrations of the surgical tool 20. As a result, the system 10 and method 12 are able to measure the impedance of the surgical tool 20. the power and voltage required to maintain the characteristic vibration displacement of the tip 26; The heating of the section 26, the energy returned to the console 22, and the components of the harmonic frequency 43 are clearly shown. In addition, the system 10 and method 12 also reduce the 0's tissue ablation performance is greatly improved.

[0069] Several embodiments have been discussed in the above description. However, the embodiments discussed herein are It is not intended to be exhaustive or to limit the present invention to any particular form. The terms used are intended to be words of description rather than of limitation. Many modifications and variations are intended to be within the scope of the present invention in light of the above teachings. It is contemplated that the present invention can be practiced otherwise than as specifically described.

[0070] The numerous features and advantages of the invention are apparent from the detailed specification and, therefore, are set forth in the appended claims. The appended claims are intended to cover all such features and aspects of the invention which fall within the true spirit and scope of the invention. Moreover, numerous modifications and variations will become apparent to those skilled in the art. therefore, it is not intended to limit the invention to the exact construction and operation as illustrated and described. It is not desirable to make modifications and improvements to the present invention without departing from the spirit and scope of the present invention. Equivalents may be used.

Claims

1. 1. A method for operating an ultrasonic surgical tool by a console having a controller to reduce the presence of harmonic signals, comprising: the controller driving the ultrasonic surgical tool with a first drive signal, the ultrasonic surgical tool exhibiting harmonic signals as a result of being driven by the first drive signal; the controller measuring a voltage across and a current through the ultrasonic surgical tool related to the first drive signal; determining a difference between a phase of a measured voltage at a fundamental frequency of the first drive signal and a phase of a measured current at a harmonic frequency of the harmonic signal resulting from driving of the ultrasonic surgical tool by the first drive signal as the characteristic obtained for the harmonic signal; the controller generating a cancellation signal based on the obtained characteristics of the harmonic signal; the controller combining the first drive signal and the cancellation signal to generate a second drive signal, the second drive signal being a sine wave; driving the ultrasonic surgical tool with the second drive signal by the controller, wherein a presence of harmonic signals resulting from driving the ultrasonic surgical tool with the second drive signal is reduced relative to a presence of harmonic signals resulting from driving the ultrasonic surgical tool with the first drive signal; The method of operation includes:

2. The operating method of claim 1, comprising the step of the controller generating the cancellation signal having a frequency corresponding to a harmonic frequency of the harmonic signal and a phase shift based on the determined phase difference.

3. The step of the controller determining an amplitude of a measured current at a harmonic frequency of the harmonic signal; generating the cancellation signal having an amplitude determined based on an amplitude of a measured current at a harmonic frequency of the harmonic signal; 3. The method of claim 1 or 2, comprising:

4. The operating method of claim 3, comprising the step of the controller generating a cancellation signal having an amplitude twice the amplitude of the measured current at the harmonic frequency of the harmonic signal.

5. An operating method as described in claim 3, comprising a step in which the controller sets the amplitude of the cancellation signal so that when the ultrasonic surgical tool is driven by the second drive signal, the tip of the ultrasonic surgical tool exhibits a desired nonlinear vibration behavior.

6. a fundamental frequency of the first drive signal corresponds to a first resonant mode of a tip of the ultrasonic surgical tool; The method comprises: generating the cancellation signal having a first frequency component and a second frequency component, the first frequency component having a first frequency corresponding to a harmonic frequency of the harmonic signal and a phase shift based on the determined phase difference, and the second frequency component having a second frequency corresponding to a second resonant mode of the tip; the controller combining the first drive signal and the cancellation signal to generate the second drive signal, the second drive signal reducing the presence of harmonic signals relative to the presence of harmonic signals resulting from driving the ultrasonic surgical tool with the first drive signal and causing the tip to vibrate simultaneously in the first resonant mode and the second resonant mode of the tip; Including, A method according to any one of claims 1 to 5.

7. The controller acquires a characteristic of a second harmonic signal generated by driving the ultrasonic surgical tool with the second drive signal; generating a second cancellation signal based on the acquired characteristic of the second harmonic signal; the controller combining the second drive signal and the second cancellation signal to generate a third drive signal; driving the ultrasonic surgical tool with the third drive signal by the controller, wherein a presence of the second harmonic signal resulting from driving the ultrasonic surgical tool with the third drive signal is reduced relative to a presence of the second harmonic signal resulting from driving the ultrasonic surgical tool with the second drive signal; A method according to any one of claims 1 to 6, comprising:

8. 1. A console for controlling an ultrasonic surgical tool to reduce the presence of harmonic signals, comprising: the console comprises a controller; The controller: driving the ultrasonic surgical tool with a first drive signal, the ultrasonic surgical tool exhibiting harmonic signals as a result of being driven by the first drive signal; measuring a voltage across and a current through the ultrasonic surgical tool related to the first drive signal; determining a difference between a phase of a measured voltage at a fundamental frequency of the first drive signal and a phase of a measured current at a harmonic frequency of the harmonic signal as the characteristic obtained for the harmonic signal; generating a cancellation signal based on the obtained characteristics of the harmonic signal; The first drive signal and the cancellation signal are combined to generate a second drive signal that is a sine wave; driving the ultrasonic surgical tool with the second drive signal, wherein a presence of harmonic signals resulting from driving the ultrasonic surgical tool with the second drive signal is reduced relative to a presence of harmonic signals resulting from driving the ultrasonic surgical tool with the first drive signal. console.

9. 9. The console of claim 8, wherein the controller generates the cancellation signal having a frequency corresponding to a harmonic frequency of the harmonic signal and a phase shift based on the determined phase difference.

10. The controller: determining an amplitude of a measured current at a harmonic frequency of the harmonic signal; generating the cancellation signal having an amplitude determined based on an amplitude of a measured current at a harmonic frequency of the harmonic signal; A console according to claim 8 or 9.

11. The console of claim 10, wherein the controller generates the cancellation signal having an amplitude twice the amplitude of the measured current at a harmonic frequency of the harmonic signal.

12. The console of claim 10, wherein the controller sets the amplitude of the cancellation signal such that when the ultrasonic surgical tool is driven by the second drive signal, the tip of the ultrasonic surgical tool exhibits a desired nonlinear vibration behavior.

13. a fundamental frequency of the first drive signal corresponds to a first resonant mode of a tip of the ultrasonic surgical tool; The controller: generating the cancellation signal having a first frequency component and a second frequency component, the first frequency component having a first frequency corresponding to a harmonic frequency of the harmonic signal and a phase shift based on the determined phase difference, and the second frequency component having a second frequency corresponding to a second resonant mode of the tip; combining the first drive signal and the cancellation signal to generate the second drive signal, the second drive signal reducing the presence of harmonic signals relative to the presence of harmonic signals resulting from driving the ultrasonic surgical tool with the first drive signal and simultaneously vibrating the tip in the first resonant mode and the second resonant mode of the tip. A console according to any one of claims 8 to 12.

14. The controller: obtaining a characteristic of a second harmonic signal resulting from driving the ultrasonic surgical tool with the second drive signal; generating a second cancellation signal based on the obtained characteristic of the second harmonic signal; generating a third drive signal by combining the second drive signal and the second cancellation signal; driving the ultrasonic surgical tool with the third drive signal, wherein a presence of the second harmonic signal resulting from driving the ultrasonic surgical tool with the third drive signal is reduced relative to a presence of the second harmonic signal resulting from driving the ultrasonic surgical tool with the second drive signal. A console according to any one of claims 8 to 13.

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