Method and system for estimating temperature of an ultrasonic instrument - Patents.com

Abstract

A method performed by a surgical system, the method determining that an ultrasonic instrument is in a low power state, the method determining a resonant frequency of an end effector of the ultrasonic instrument and determining a temperature of the end effector based on the resonant frequency, and a notification is displayed on a display of the surgical system based on the temperature.

Description

[Technical field]

[0001] Various aspects of the present disclosure relate generally to a surgical system, and more particularly, to a surgical system for estimating a temperature of an ultrasonic instrument. Other aspects are also described. [Background technology]

[0002] Minimally-invasive surgery (MIS), such as laparoscopic surgery, uses techniques that aim to reduce tissue damage during surgical procedures. Laparoscopic procedures typically require making multiple small incisions in a patient, e.g., the abdomen, through which several surgical tools, such as an endoscope, blades, graspers, and needles, are then inserted into the patient. Gas is insufflated into the abdomen, which inflates the abdomen, thereby providing more space around the tips of the tools and making it easier for the surgeon to see (through the endoscope) and manipulate the tissue at the surgical site. MIS can be performed faster and with less surgeon fatigue using a surgical robotic system in which the surgical tools are operably attached to the distal end of a robotic arm and a control system actuates the arm and its attached tools. The tips of the tools mimic the movement of the position and orientation of a handheld user input device (UID) as the UID is being manipulated by the surgeon. A surgical robotic system may have multiple surgical arms, one or more of which have an attached endoscope and other surgical arms have attached surgical instruments for performing certain surgical actions.

[0003] Control inputs from a user (e.g., a surgeon or other operator) are captured via one or more user input devices and then translated into control of the robotic system. For example, in response to user commands, a tool drive having one or more motors can actuate one or more degrees of freedom of a surgical tool when the surgical tool is positioned at a surgical site on a patient. Summary of the Invention [Means for solving the problem]

[0004] Surgical tools used in some MIS procedures are ultrasonic instruments that use ultrasonic vibrations at their tips to rapidly generate heat for cutting and cauterizing tissue. The tips may include blades that reach high temperatures (e.g., greater than 300° C.) during a “heating” cycle in which the blade oscillates against a portion of tissue, thereby generating heat due to friction between the blade and tissue during the oscillating motion. After reaching a high temperature, the blade may be used to simultaneously incise a portion of tissue while also sealing the remaining tissue. By performing multiple tasks (e.g., cutting to incise, cauterizing, etc.), the use of tools during laparoscopic surgery reduces instrument changes and the number of instruments during a procedure.

[0005] Conventional laparoscopic surgery systems may be capable of estimating the temperature of an ultrasonic instrument blade during a blade heating cycle. Specifically, such systems may activate the instrument by providing power to oscillate the instrument blade (e.g., in response to receiving user input by an operator, such as pressing a petal) when used to incise tissue. While the instrument is active, the system may determine the temperature of the blade based on one or more characteristics of the instrument (e.g., input voltage, input current, etc.). However, after the heating cycle is completed (e.g., after the operator releases the petal), conventional systems cease providing power to the ultrasonic instrument. At this point, the blade enters a "cooling" cycle, where the heat generated during the heating cycle dissipates because the blade is no longer oscillating and therefore no frictional heat is being generated. During this cooling cycle, conventional laparoscopic surgery systems do not provide the instrument operator with the real-time temperature of the blade. Specifically, these systems may be unable to determine the temperature of the blade (e.g., current temperature) because the characteristics (e.g., input voltage) used to determine the temperature during the heating cycle are no longer available because the instrument is no longer powered. As a result, if an operator manipulates surrounding tissue with an instrument while the blade is still hot (e.g., before the end of a cooling cycle when the blade falls below a temperature threshold), the residual heat on the blade may inadvertently cause thermal damage to potentially sensitive tissue. In addition, an operator may not know with reasonable certainty the exact moment when the residual heat has dissipated sufficiently for the ultrasonic instrument to manipulate (or contact) tissue without causing damage. For example, the temperature of the blade may change during use based on the type / thickness of tissue the operator was actively cutting / cauterizing. As a result of the changing temperature, the blade may cool differently once the task is completed and the instrument goes into its cooling cycle. Thus, there is a need for a surgical system that is configured to estimate (or predict) the temperature of an ultrasonic instrument while the instrument is not using ultrasonic vibrations to heat its blade (e.g., during a cooling cycle).

[0006] The present disclosure provides a surgical system that estimates the temperature of an ultrasonic instrument while the instrument is in a "low power" state (or cooling cycle) in which the instrument does not draw (e.g., enough) power to heat the end effector of the instrument. The system determines that the ultrasonic instrument is in a "low power" state (or cooling cycle) in which the ultrasonic instrument does not draw (e.g., enough) power to heat the end effector as the ultrasonic instrument does during a "high power" state (or heating cycle) in which the ultrasonic instrument draws power to heat the end effector. For example, the ultrasonic instrument may be coupled to a generator that is arranged to provide a current to the instrument based on received user input (e.g., an operator pressing a pedal). This current causes the instrument to vibrate the blade of the end effector to generate heat at an elevated temperature. However, while in this low power state, the ultrasonic instrument may draw less power (e.g., to provide less current) than while the instrument is in a high power state in order to vibrate the blade less. This lesser vibration may be insufficient to generate heat in the blade. While the ultrasonic instrument is in this low power state, the system may determine a resonant frequency of the end effector (e.g., a blade while vibrating through a lower range of motion than required to generate heat). The system may determine a temperature of the end effector based on the resonant frequency. For example, the system may apply the resonant frequency (which may be at least one input) to a (e.g., predefined) model that produces a temperature as an output. The system may display a notification on a display based on the temperature, such as displaying the determined temperature. Thus, the present disclosure may provide real-time temperature information to help an operator assess whether the end effector is within a safe range for contacting tissue, rather than having the operator guess as to whether the end effector has cooled.

[0007] In one aspect, the end effector may be a grasper as described herein, the grasper including a blade (e.g., as one jaw) that vibrates along a longitudinal axis of the blade while the ultrasonic instrument is in a high power state to generate heat. Additionally, the grasper may include a hinged jaw rotatably coupled to a joint of the grasper, the hinged jaw being arranged to rotate relative to the blade to open and close the grasper. In some aspects, the resonant frequency may be determined in response to determining that the grasper is in an open position with the hinged jaw rotated away from the blade.

[0008] The above summary does not include an exhaustive list of all aspects of the present disclosure. The present disclosure is intended to include all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the following "Description of the Preferred Embodiments" and particularly those pointed out in the "Claims". Such combinations may have certain advantages not specifically described in the above summary. [Brief description of the drawings]

[0009] The embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference symbols indicate similar elements. It should be noted that references to "an" or "one" embodiment in this disclosure are not necessarily to the same embodiment, but rather they mean at least one. Also, for purposes of brevity and reducing the total number of figures, a given figure may be used to illustrate features of more than one embodiment, and not all elements in a figure may be required for a given embodiment. [Figure 1] 1 shows a pictorial representation of an exemplary surgical system in an operating room. [Diagram 2] 1 shows a pictorial diagram of an ultrasonic instrument and generator according to one aspect of the present disclosure. [Diagram 3] 3 illustrates an end effector of the ultrasonic instrument of FIG. 2. [Figure 4] FIG. 1 is a block diagram of a surgical system according to one aspect. [Diagram 5] FIG. 1 is a flow diagram of a process for determining the temperature of an end effector of an ultrasonic instrument in a low power state. [Figure 6] 1 illustrates several stages of a display of a surgical system showing actions taken by an end effector of an ultrasonic instrument and showing notifications based on the determined temperature of the end effector. [Figure 7] FIG. 13 is a flow diagram of a process for an embodiment of determining the temperature of an end effector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Some aspects of the present disclosure will now be described with reference to the accompanying drawings. Whenever the shape, relative position, and other aspects of parts described in a given aspect are not explicitly defined, the scope of the disclosure herein is not limited to only the parts shown, which are intended for illustrative purposes only. Also, although numerous details are described, it is understood that some aspects can be practiced without these details. In other cases, well-known circuits, structures, and techniques have not been shown in detail so as not to obscure the understanding of this description. Furthermore, unless the meaning is clearly to the contrary, all ranges described herein are considered to include the endpoints of each range.

[0011] FIG. 1 shows a pictorial view of an exemplary surgical system (which may hereafter be referred to as the "system") 1 in an operating room. The system 1 includes a user console 2, a control tower 3, and one or more surgical robotic arms 4 on a surgical robot table (surgical table or surgical platform) 5. In one aspect, the arms 4 may be mounted to a table or bed on which a patient lies, as shown in the example of FIG. 1. In one aspect, at least some of the arms 4 may be configured differently. For example, at least some of the arms may be mounted to another suitable structural support, such as a ceiling, a side wall, or a cart separate from the table. The system 1 may incorporate any number of devices, tools, or accessories used to perform surgery on a patient 6. For example, the system 1 may include one or more surgical tools (instruments) 7 used to perform the surgery (surgical procedure). The surgical tools 7 may be end effectors for performing the surgical procedure that are attached to the distal end of the surgical arms 4.

[0012] Each surgical tool 7 may be manipulated manually, robotically, or both during surgery. For example, the surgical tool 7 may be a tool used to enter, view, or manipulate the internal anatomy of the patient 6. In one aspect, the surgical tool 7 is a grasper capable of grasping the patient's tissue. The surgical tool 7 may be controlled manually by a bedside operator 8 or robotically via actuated movement of a surgical robot arm 4 to which the surgical tool is attached. For example, when manually controlled, the operator may (e.g., physically) hold a portion of the tool (e.g., a handle) and manually control the tool by moving the handle and / or pressing one or more input controls (e.g., buttons) on the tool (e.g., the tool's handle). In another aspect, when robotically controlled, the surgical system may manipulate surgical tool-based user inputs (e.g., received via a user console 2 as described herein).

[0013] In general, a remote operator 9, such as a surgeon or other operator, may use the user console 2 to operate the arm 4 and / or attached surgical tool 7 remotely, e.g., during teleoperation. The user console 2 may be located in the same operating room as the rest of the system 1, as shown in FIG. 1. However, in other environments, the user console 2 may be located in an adjacent or nearby room, or in a remote location, e.g., in a different building, city, or country. The user console 2 may include one or more components, such as a seat 10, one or more foot-operated controls (or foot pedals) 13, one or more (handheld) user input devices (UIDs) 14, and at least one display 15. The display may be configured to display, e.g., a view of a surgical site inside the patient 6. The display may be configured to display image data (e.g., still images and / or video). In one aspect, the display can be any type of display, such as, for example, a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, etc. In some aspects, the display can be a 3D immersive display for displaying a 3D (surgical) representation. For example, during a surgical procedure, one or more endoscopic cameras can capture image data of a surgical site that the display presents to a user in 3D. In one aspect, the 3D display can be a naked eye stereoscopic display that provides a 3D perception to a user without the need for special glasses. As another example, the 3D display can be a stereoscopic display that uses glasses to provide a 3D perception (e.g., via active shutters or polarization).

[0014] In another aspect, the display 15 may be configured to display in one final graphical user interface (GUI) that may provide informative and / or interactive content to assist the user in performing a surgical procedure with one or more instruments in the surgical system 1. For example, some of the displayed content may include image data captured by one or more endoscopic cameras, as described herein. In another aspect, the GUI may include selectable UI items that, when manipulated by the user, may cause the system to perform one or more actions. For example, the GUI may include UI items as interactive content for switching control between robotic arms. In one aspect, to interact with the GUI, the system may include an input device, e.g., a keyboard, a mouse, etc. In another aspect, a user may interact with the GUI using the UID 14. For example, a user may manipulate the UID (e.g., with a cursor) to navigate through the GUI, and may hover the cursor over a UI item and manipulate the UID (e.g., select a control or button) to make a selection. In some aspects, the display may be a touch-sensitive display screen. In this case, the user may make a selection by navigating and selecting through touching the display. In some aspects, any method may be used to navigate and / or select UI items.

[0015] As shown, a remote operator 9 sits on a seat 10 and views a user display 15 while operating a foot-operated control 13 and a handheld UID 14 to remotely control one or more of an arm 4 and a surgical tool 7 (mounted at the distal end of the arm 4).

[0016] In some variations, a bedside operator 8 may also operate the system 1 in a "bed-facing" mode, where the bedside operator 8 (user) is present near the patient 6 and is simultaneously operating a robotically driven tool (end effector attached to arm 4) with, for example, a handheld UID 14 held in one hand, along with a manual laparoscopic tool. For example, the bedside operator's left hand may be operating the handheld UID to control the robotic components, while the bedside operator's right hand may be operating a manual laparoscopic tool. Thus, in these variations, the bedside operator 8 may perform both robotically assisted minimally invasive surgery and manual laparoscopic surgery on the patient 6.

[0017] During an exemplary procedure, the patient 6 is sterilely prepped and draped to achieve anesthesia. Initial access to the surgical site may be performed manually while the arms of the system 1 are in a stowed or retracted configuration (thereby facilitating access to the surgical site). Once access is complete, initial positioning or preparation of the system 1 including its arms 4 may be performed. A remote operator 9 at the user console 2 then proceeds with the procedure by utilizing the foot control 13 and UID 14 to operate the various end effectors and possibly an imaging system to perform the procedure. Manual assistance may also be provided at the procedure bed or table by sterile gowned bedside personnel, such as a bedside operator 8, who may perform tasks such as retracting tissue, performing manual repositioning, and replacing one or more tools of the robotic arms 4. Non-sterile personnel may also be present to assist the remote operator 9 at the user console 2. Once the procedure or surgery is completed, the system 1 and user console 2 may be configured or set to a state to facilitate post-operative procedures such as cleaning or sterilization and entering or printing medical records via the user console 2.

[0018] In one aspect, the remote operator 9 holds and moves the UID 14 to provide input commands to drive (move) one or more robotic arm actuators 17 (or drive mechanisms) of the system 1 for remote operation. The UID 14 may be communicatively coupled to the rest of the system 1, for example, via the console computer system 16 (or host). The UID 14 may generate spatial state signals corresponding to the movements of the UID 14, e.g., the position and orientation of the UID's handheld housing, which may be input signals for controlling the movement of the robotic arm actuators 17. The system 1 may use control signals derived from the spatial state signals to control the proportional movement of the actuators 17. In one aspect, a console processor of the console computer system 16 receives the spatial state signals and generates corresponding control signals. Based on these control signals, which control how the actuators 17 are energized to drive segments or links of the arm 4, the movements of the corresponding surgical tools attached to the arm may mimic the movements of the UID 14. Similarly, interaction between the remote operator 9 and the UID 14 may generate grip control signals that, for example, cause the jaws of a grasper on the surgical tool 7 to close and grip tissue of the patient 6 .

[0019] System 1 may include several UIDs 14, where for each UID a respective control signal is generated that controls the actuators of the respective arms 4 and the surgical tools (end effectors). For example, the teleoperator 9 may move a first UID 14 to control the movement of an actuator 17 in the left robotic arm, where that actuator responds by operating joints, gears, etc. in that arm 4. Similarly, movement of a second UID 14 by the teleoperator 9 controls the movement of another actuator 17, which in turn drives other joints, gears, etc. in system 1. System 1 may include a right arm 4 on the right side of a patient fixed to a bed or table, and a left arm 4 on the left side of the patient. The actuators 17 may include one or more motors that are controlled to drive the rotation of the joints of the arm 4 to change the orientation of, for example, an endoscope or grasper of a surgical tool 7 attached to that arm, relative to the patient. The movement of several actuators 17 in the same arm 4 can be controlled by spatial state signals generated from a particular UID 14. The UIDs 14 can also control the movement of respective surgical tool graspers. For example, each UID 14 can generate a respective grasp signal to control the movement of an actuator, such as a linear actuator, that opens and closes the jaws of a grasper at the distal end of the surgical tool 7 to grasp tissue within the patient 6.

[0020] In some embodiments, communication between the surgical robot table 5 and the user console 2 may be through a control tower 3, which may translate user commands received from the user console 2 (more specifically, from the console computer system 16) into robotic control commands sent to the arm 4 on the surgical table 5. The control tower 3 may also transmit status and feedback from the surgical table 5 to the user console 2. The communication connections between the surgical table 5, the user console 2, and the control tower 3 may be via wired (e.g., fiber optic) and / or wireless links using any suitable of a variety of wireless data communication protocols, for example, the BLUETOOTH protocol. Any wired connections may optionally be built into the floor and / or walls or ceiling of the operating room. The system 1 may provide video output to one or more displays, including displays in the operating room as well as remote displays accessible via the Internet or other networks. The video output or feed may also be encrypted to ensure privacy, and all or portions of the video output may be stored on a server or electronic medical record system.

[0021] 2 shows a pictorial diagram of an ultrasonic instrument 20 and generator 25 according to one embodiment of the present disclosure. As shown, the ultrasonic instrument is a handheld laparoscopic tool configured to perform ultrasonic surgical procedures (e.g., cutting and sealing tissue) based on manual manipulation of the instrument (e.g., of hand grip 21) by an operator (e.g., a surgeon). The ultrasonic instrument is coupled (e.g., via a cable) to a generator that allows the ultrasonic instrument to operate in one or more power states, as described herein.

[0022] In accordance with aspects of the present technology, an ultrasonic instrument includes a hand grip (e.g., including a tool driver) 21, a cannula 22, and an end effector 23 (e.g., which may be coupled to the shaft of the instrument) loaded within the cannula.

[0023] The hand grip 21 is positioned to be held by an operator and allows the operator to manipulate the ultrasonic instrument (e.g., its end effector 23) during a surgical procedure. In one embodiment, the hand grip may include one or more inputs (e.g., a trigger, one or more buttons, etc.) that allow the operator to control the ultrasonic instrument. For example, the instrument may include a trigger that generates a control signal in response to a user input by pulling the trigger with one or more fingers while holding the hand grip. In one embodiment, the trigger may be positioned to manipulate the end effector (e.g., by adjusting the position of the hinged arm 31 shown in FIG. 3). In another embodiment, the hand grip may include one or more inputs to change the power state of the instrument.

[0024] As described herein, the hand grip may include a tool drive arranged to drive the end effector 23 of the ultrasonic instrument. In particular, the tool drive may include a (e.g., linear) motor or actuator arranged to vibrate (or rock) the end effector at one or more frequencies (e.g., very high (ultrasonic) frequencies and low frequencies). In some aspects, the tool drive is configured to vibrate the end effector such that a portion of the end effector (e.g., a blade) moves back and forth along one or more axes. In particular, the tool drive may vibrate the end effector through one or more ranges of motion, and through each range of motion, the end effector may be displaced a different distance from a starting (or originating) position. Further description of how the end effector vibrates is described herein. In another aspect, the tool drive may include an ultrasonic transducer configured to vibrate the end effector according to an input voltage / current (e.g., applied by generator 25).

[0025] As previously described, an ultrasonic instrument may include an end effector 23 and a tool driver 21. In one aspect, the ultrasonic instrument may be separate from (and removably coupled to) the tool driver. In that case, the ultrasonic instrument referred to herein may be an end effector that may be coupled to a hand grip (e.g., to the tool driver via a cannula in the hand grip). Specifically, a cannula may be coupled to the hand grip, which receives and guides the ultrasonic instrument (e.g., its shaft) for coupling to the instrument. By being separate from the hand grip, this may allow multiple different tools to be coupled to the hand grip. In this case, the cannula 22 may receive and guide one or more surgical instruments, e.g., an endoscope, a stapler, etc.

[0026] As described herein, the surgical system 1 includes an ultrasonic instrument 20 configured to generate heat based on vibration of its end effector 23. In another embodiment, the instrument can be any type of energy (e.g., laparoscopic) tool designed to generate heat.

[0027] As described thus far, the ultrasonic instrument 20 may be a handheld laparoscopic instrument that may be manually held and operated by an operator. In another embodiment, the instrument may be part of a surgical robotic arm. Specifically, the ultrasonic instrument may be coupled to a robotic arm and powered by a generator as described herein. For example, the ultrasonic instrument may be coupled to a distal end of a robotic arm (e.g., arm 4 in FIG. 1 ), which includes several components that allow the robotic arm to be controlled by an operator. For example, the surgical robotic arm 104 may include multiple links and multiple actuation joint modules for actuating the multiple links relative to one another. The joint modules may include various types, such as pitch joints or roll joints, which may substantially constrain the movement of adjacent links relative to others about a particular axis. The multiple joint modules of the robotic arm 104 may be actuated to position and orient the ultrasonic instrument for robotic surgery. In one embodiment, the ultrasonic instrument may be coupled to the distal end via a tool drive that is arranged to actuate the end effector 23 of the instrument.

[0028] When an ultrasonic instrument is coupled to a robotic arm, movement and manipulation of the ultrasonic instrument may be accomplished via one or more user controls (e.g., UID, foot pedals, etc.) coupled to the surgical system. For example, the UID may be arranged to open and close the gripper 23 of the ultrasonic instrument and / or to adjust the spatial position (in space) of the gripper based on user input (e.g., the position of the UID).

[0029] Referring to Figure 3, this figure shows the end effector 23 of the ultrasonic instrument of Figure 2. Specifically, this figure shows that the end effector is a grasper (or gripping device) that is received through a cannula 22 and includes a blade 30 (e.g., as one jaw) and a hinged arm (or jaw) 31 that is rotatably coupled to a joint (or robotic wrist) 32. In particular, the blade is received (and extends) through the cannula and is positioned to couple to a tool drive (e.g., of the hand grip 21) so that the blade oscillates further back within the cannula. The hinged arm 31 is rotatably coupled (at joint 32) to the cannula 22 and is positioned to rotate. The grasper is positioned to open and close based on the rotational position of the hinged arm about the joint's axis of rotation (e.g., the Z-axis) relative to the blade (and / or cannula). For example, the grasper is positioned to open (or be in an open position) when the hinged arm is rotated (e.g., a threshold distance) away from the blade. While in this position, the end effector can be oriented such that an object, such as tissue, can be disposed between the blade and the hinged arm (e.g., by moving the end effector around the object). The grasper can close (or be in a closed position) when the hinged arm is rotated (e.g., within a threshold distance) towards the blade, whereby the grasper can grasp an object between the blade and the hinged arm. As described herein, the hinged arm can be positioned to apply pressure against a grasped object (e.g., crushing the object between the jaws) to grip the object and / or make an incision on the object.

[0030] As described herein, the blade 30 is a jaw of a grasper. In particular, the blade is a jaw that cannot rotate (e.g., about the Z axis) relative to the end effector. The blade can be arranged to oscillate along its longitudinal axis (e.g., the Y axis) while the ultrasonic instrument is in a high power state (or mode) to generate heat. In particular, the blade can be driven (e.g., by a tool drive in the hand grip 21) to move back and forth (e.g., linearly) along the longitudinal axis of the end effector (and through a cannula as described herein) to repeatedly displace the blade 30 at a (e.g., constant) frequency. Specifically, the blade can oscillate (e.g., move back and forth) through a range of motion (or displacement) in which the blade moves a distance (e.g., forward or away from the end effector) from a starting position and then moves back the same distance. In one aspect, the range of motion can be the distance the blade moves from a starting position to an extended position. In another aspect, the range of motion can be the distance that the blade moves back and forth.

[0031] As described herein, the blade may generate frictional heat while vibrating against an object. Specifically, the blade may contact tissue while the grasper is crushing the tissue between the two jaws and may vibrate against the tissue. As the blade vibrates, the end effector may cut and / or cauterize the tissue as described herein. In one aspect, the blade may vibrate differently (e.g., through different ranges of motion) based on the power state of the ultrasonic instrument (e.g., how much power is provided). Further description of the vibrating blade and power states of ultrasonic instruments are described herein.

[0032] Returning to FIG. 2 , the generator 25 is configured to control and provide power to the ultrasonic instrument to control (e.g., heat) the end effector 23 while the instrument is coupled to the generator and in use by an operator (e.g., during a laparoscopic procedure to manipulate tissue and / or perform one or more surgical tasks on tissue, e.g., to cut, seal blood vessels, and / or cut, grasp, and dissect tissue). In particular, the generator may provide power to the ultrasonic instrument such that the surgical system 1 (e.g., its ultrasonic instrument) may operate in one of one or more power states. For example, the generator may provide power to the instrument such that the ultrasonic instrument is in a “high power” state (or “heat cycle”), in which the instrument draws power (or current) from the generator (e.g., at a particular voltage) to generate heat in the end effector 23. For example, the generator may provide a (e.g., first) electrical current (or input current) to a hand grip (e.g., a tool drive of the hand grip) of the ultrasonic instrument, which may use this electrical current to drive the blade 30 to oscillate (or swing) through a (first) range of motion (and at a particular frequency). Frictional heat may be generated by the end effector while the blade of the end effector is oscillated through this range of motion against an object, such as tissue, as described herein. In another aspect, the ultrasonic instrument may be placed to operate in a "low power" state (or "cooling cycle"), where the ultrasonic instrument no longer draws (enough or as much) power provided by the generator to heat the end effector while the instrument was in a high power state. Specifically, while in this state, the generator may be configured to provide less power to the ultrasonic instrument than was provided by the generator while the instrument was in a high power state, such that the end effector does not generate heat (e.g., when in contact with an object). In particular, the generator may provide a current (e.g., a second current) to the ultrasonic instrument that is less than the (first) current provided by the generator while the instrument is operating in a high power state, and as a result, this does not cause heat in the end effector (or as little heat as when the ultrasonic instrument is in a high power state).As a result, the ultrasonic instrument may begin to cool when entering a low power state from a high power state. Eventually, if kept in the low power state, the ultrasonic instrument will cool down (at least) to a threshold temperature (e.g., room temperature). In one aspect, the second current may be less than a predefined threshold current. In one aspect, the blade may vibrate at the same frequency in the low power state as in the high power state. In another aspect, the blade may vibrate within an allowed frequency range.

[0033] As a result, due to the smaller current provided to the instrument while in the low power state, the blade of the end effector may be driven by the tool driver 21 differently than when the instrument is in the high power state. In particular, the blade may oscillate through a range of motion that is different from the range of motion through which the blade oscillates while the instrument is in the high power state. For example, while in the high power state, the blade may oscillate through a first (e.g., high) range of motion, which may cause the blade to heat up when pressed against an object, while while in the low power state, the blade may oscillate through a second (lower) range of motion that may be smaller than the first range of motion (e.g., the blade is displaced less along the longitudinal axis than the first range of motion). In some aspects, the second range of motion may be smaller than a minimum threshold (e.g., a threshold above which the blade will generate heat if it oscillates above the minimum threshold). In one aspect, the end effector may not generate frictional heat while oscillating through this lower range of motion and while pressed against an object such as a blood vessel. In one aspect, the resonant frequency is maintained within an acceptable range regardless of what power state the instrument is operating in.

[0034] In one aspect, the difference in vibration of the end effector may be based on the amount of power being drawn by the ultrasonic instrument while in the different states. For example, the range of motion displaced while the blade is oscillating may be based on (e.g., proportional to) the power drawn by the instrument, whereby more power drawn by the instrument may cause the blade to oscillate over a higher range of motion. Conversely, while the ultrasonic instrument is in a low power state, the instrument may draw less power, causing the blade to oscillate less (than while the instrument is in a low power state). As a result of the oscillation over a smaller displacement, the blade may not generate frictional heat (e.g., while in contact with tissue). In another aspect, the blade may be in a low power state and generate some frictional heat while in contact with an object, but less than the heat generated while the instrument is in a high power state. In this case, this generated frictional heat may not be sufficient to cut and / or seal tissue. In some aspects, as a result of operating in the low power state, the end effector of the ultrasonic instrument may enter a cooling cycle, whereby heat generated by the end effector while the instrument was in the high power state dissipates (e.g., over a period of time). In another aspect, the blade may not vibrate (e.g., the tool drive 21 may not drive the blade) while in this low power state.

[0035] In one aspect, the system may enter (or operate in) at least one of the power states based on a user input (e.g., received by the generator 25). In particular, the generator may provide power to the ultrasonic instrument based on receiving a user input to one or more input devices (e.g., input to the foot petals, a UID controlled by an operator and communicatively coupled to the system 1, and / or an input at the hand grip 21 of the ultrasonic instrument). The power provided based on the user input may place the ultrasonic instrument in a high power state in which the ultrasonic instrument draws power from the generator to heat the end effector 23 (e.g., the blade 30 of the end effector 23). For example, when the generator receives a (first) user input (e.g., by the operator pulling or pressing a trigger on the hand grip 21), the generator may provide an electric current to the ultrasonic instrument (e.g., the tool drive 21 of the ultrasonic instrument), which uses the electric current to drive the end effector, as described herein. Thus, if the trigger controls the hinged arm of the end effector, the generator is configured to provide current when the hinged arm is moved (e.g., at least a threshold distance toward the blade 30). In another aspect, the system may enter a lower power state based on another (e.g., a second) user input (e.g., receiving input from a different input device coupled to the generator, such as a foot pedal).

[0036] In some aspects, the ultrasonic instrument may be arranged to switch between a high power state and a low power state. As described herein, the instrument may operate in the high power state while the generator receives a user input (e.g., a user pulling or pressing a trigger on a hand grip). The instrument may operate in the low power state in response to the generator not receiving a user input. For example, the ultrasonic instrument may switch from a high power state to a low power state in response to a user releasing a trigger on a hand grip, and the generator may transition between the two states). In one aspect, as described herein, the instrument may operate in a low power state while an operator is not actively using the instrument to perform ultrasonic instrument operations. Specifically, the system may enter a low power state, but no user input is received to one or more input devices used by the operator to enter the high power state. However, once the operator desires to actively use the ultrasonic instrument, the ultrasonic instrument may switch back to the high power state (e.g., in response to a user input). In another aspect, the instrument may operate in the low power state in response to receiving a user input (e.g., a user pressing a button on the UID). In another aspect, the instrument may operate in this state for a period of time. As described herein, the surgical system is configured to determine the temperature of the end effector while in the low power state (e.g., after switching from the high power state) to inform the operator of the temperature that may be high due to the instrument operating in the high power state. Once the end effector cools to a certain temperature (e.g., below a predefined temperature), the generator may shut down the instrument by ceasing to provide a lower current since at this temperature the end effector may not cause thermal damage when in contact with tissue.

[0037] In one aspect, the generator may provide different levels of current to heat the blade, which may be based on user input. For example, the generator may receive a first user input (e.g., from one petal coupled to the generator) and, in response, provide a maximum (allowable) amount of current to the ultrasonic instrument. The ultrasonic instrument may then drive the end effector through a maximum (e.g., predefined) range of motion, which may result in the end effector generating heat at a (first) high temperature. However, when the generator receives a second user input (e.g., from another petal coupled to the generator), the generator may provide a lower amount of current to the ultrasonic instrument. As a result, the ultrasonic instrument may draw less power to vibrate the end effector through a (second) lower range of motion, which may be lower than the first range of motion at which the blade vibrates in response to the first user input. However, this lower range of motion may cause the end effector to heat at a lower temperature than the first temperature of the end effector when the ultrasonic instrument draws more current (in response to the generator receiving a first user input). By heating the end effector to different temperatures, different types of tissue may be cut and / or cauterized. For example, fatty tissue may require the end effector to be hotter (having a first temperature) while thinner (and less fatty) tissue may require less heat (having a second temperature) to cut and / or cauterize the tissue. In another aspect, the generator may be configured to provide one current while in a high power state (e.g., drive the end effector through a first high range of motion).

[0038] As described herein, an ultrasonic instrument may be activated (e.g., may operate in a high power state) based on whether the end effector is in a closed position to grasp an object (e.g., a portion of tissue). For example, an ultrasonic instrument may be activated (e.g., by a user) such that the ultrasonic instrument may operate in a high power state to draw sufficient current to cause heat in the end effector. In particular, the generator may activate the ultrasonic instrument upon receiving a user input to close the end effector (e.g., to move the hinged arm 31 within a distance of the blade 30). When a user input to move the hinged arm is received, the generator may be configured to provide (e.g., sufficient) power to activate the instrument, as described herein. In some aspects, the generator may activate the instrument based on a determination that the hinged arm and / or the blade are in contact with an object. For example, an ultrasonic instrument may include one or more sensors (e.g., force sensors) that detect the presence of an object and / or that an object is in contact with both arms. Upon making this determination, the generator may provide a first electrical current to cause the blade to oscillate in order to generate heat in the blade.

[0039] In one aspect, the surgical system (e.g., its generator) may be configured to determine one or more characteristics of the ultrasonic instrument while the instrument is in one or more power states. For example, the generator may be configured to track (or monitor) characteristics such as the input voltage, input current, resonant state, and / or resonant frequency of the ultrasonic instrument. In one aspect, the generator may be configured to monitor at least some of these characteristics of the instrument while the instrument is operating in a high power state. However, unlike conventional systems that cannot determine characteristics while the ultrasonic instrument is in a cooling cycle because the instrument is turned off (e.g., no power is being provided by the generator), the surgical system of the present disclosure can determine characteristics while the instrument is in a low power state (or cooling cycle) because the instrument draws at least some power. For example, the generator may determine the resonant frequency of the end effector (e.g., the blade 30 of the end effector) while in a low power state.

[0040] In one aspect, the surgical system may include additional components. For example, the system may include a cable connecting the generator to an ultrasonic instrument (e.g., an ultrasonic transducer configured to convert a current drive signal into mechanical vibrations). In one aspect, the ultrasonic transducer may be connected to a waveguide that is connected to the blade 30 of the end effector 23.

[0041] As also shown, the generator 25 includes a display 24 arranged to disclose information regarding the operation of the ultrasonic instrument. For example, the display may present temperature information, what state the ultrasonic instrument is currently in, and one or more of the characteristics described herein.

[0042] 4 is a block diagram of a surgical system 1 according to one embodiment. The system includes an ultrasonic instrument 20, a generator 25, a controller 40, a display 15, and a speaker 43 (which may be a stand-alone speaker or part of the system's electronic devices, such as a user console 2). In one embodiment, the system may include more or fewer elements, such as having more than one display and / or no speaker.

[0043] In some aspects, the controller 40 may be a dedicated processor, such as an application-specific integrated circuit (ASIC), a general-purpose microprocessor, a field-programmable gate array (FPGA), a digital signal controller, or a set of hardware logic structures (e.g., filters, arithmetic logic units, and dedicated state machines). In one aspect, the controller may be part of an electronic device, such as the console computer system 16, the tower 3, and / or the user console 2. Although illustrated as a single component, in one aspect, the controller may comprise one or more electronic components (e.g., processor, memory, etc.) communicatively coupled on a single electronic device (such as the console computer 16) or across multiple devices (e.g., communicating via a wireless computer network). In some aspects, the controller may be part of a separate device, such as part of a remote server in communication with one or more electronic devices. In another aspect, the controller may be part of the generator 25 (e.g., may be at least partially integrated within the generator 25). In that case, at least some of the other elements (e.g., the speaker and display) may also be part of (integrated within) the generator, and as a result, at least some of the operations performed by the controller described herein may be performed by the generator.

[0044] As described herein, the controller is configured to perform temperature estimation operations for the surgical system 1 to determine a (e.g., real-time) temperature of the ultrasonic instrument (e.g., its end effector) while the instrument is in a low power state (e.g., a state in which it is not actively heated to cut and / or seal tissue). In particular, the controller may determine the temperature based on one or more characteristics of the ultrasonic instrument determined while in a low power state, such as a resonant frequency of the end effector (e.g., its blade). At least some of the operations performed by the controller may be implemented in software (e.g., as instructions) stored in a memory of the surgical system (and / or stored in a memory of the controller), executed by the controller, and / or implemented by a hardware logic structure. In one aspect, at least some of the operations performed by the controller may be performed each time the instrument enters a low power state.

[0045] As shown, the generator may receive a user input (e.g., via one or more electronic devices coupled to the generator) to cause the generator to perform one or more actions. For example, a user input may be received via an ultrasonic instrument (e.g., when a user pulls a trigger on a hand grip) to cause the generator to provide a current that switches the ultrasonic instrument from a low power state to a high power state, as described herein.

[0046] FIG. 5 is a flow diagram of a process 60 for determining the temperature of an end effector of an ultrasonic instrument in a low power state. In particular, at least some of these operations may be performed once and / or while the ultrasonic instrument is in a low power state. For example, as described herein, operations may be performed (e.g., each time) the ultrasonic instrument switches from a high power state to a low power state, which may be based on user input. The surgical system may then perform these operations to estimate the temperature of the ultrasonic instrument and output (e.g., display) in real time to the operator of the instrument. In one aspect, the process may be performed by the surgical system 1. For example, each of the processes may be performed by the controller 40. As another example, at least some of the operations may be performed by the generator 25 (e.g., by one or more processors thereof). This figure is therefore described with reference to FIG. 4.

[0047] The process begins (at block 61) by the controller determining a baseline (or initial) resonant frequency of the end effector of the ultrasonic instrument 20. For example, the controller may determine the baseline resonant frequency of the end effector blade 30 at an initial time t0 as RF(t0). In one aspect, the controller may determine this baseline resonant frequency when the ultrasonic instrument 20 is coupled (e.g., plugged in) to the generator 25. For example, when the instrument is plugged into the generator, the generator may perform one or more diagnostic operations on the instrument. Based on these operations, the generator may determine the baseline resonant frequency of the end effector blade and provide the frequency to the controller. In some aspects, the generator determines the resonant frequency electronically. For example, the generator may sense the voltage and current waveforms (as well as the phase angle difference between the two waveforms) used to drive the end effector blade. In particular, the ultrasonic instrument 20 (e.g., tool driver) may include an ultrasonic transducer configured to vibrate the blade according to input voltage and current waveforms. The frequency that produces a threshold (e.g., zero) phase angle difference is the resonant frequency. In one embodiment, the generator may continue to drive the ultrasonic transducer at resonance and adjust the output voltage (which may be called phase locking) to continue to drive at resonance (as the resonant frequency changes with temperature changes). In another embodiment, the controller 40 may adjust the output frequency. In another embodiment, other known methods may be used to determine the resonant frequency.

[0048] In some aspects, this baseline frequency may be determined while the end effector is at room temperature (or near room temperature) (e.g., a temperature of 20-25° C.). In another aspect, the baseline frequency may be determined once and stored in memory of the surgical system 1 (e.g., controller 25). For example, the baseline frequency may be determined when an instrument is initially coupled to the generator. In another aspect, the baseline resonant frequency may be determined each time an ultrasonic instrument is plugged into the generator. In another aspect, the baseline frequency may be determined at the start of (e.g., during initial power up) the surgical system (e.g., the ultrasonic instrument with the surgical system).

[0049] In one aspect, the operations performed in this block may be omitted from process 60. For example, as described herein, at least some of these operations may be performed each time the ultrasonic instrument enters a low power state. However, the baseline frequency determination may be performed once (e.g., during initial power up) in some aspects. As a result, process 60 may omit this operation in subsequent (at least partial) executions of the process.

[0050] The controller 40 is configured to determine that the end effector is in an open position while the ultrasonic instrument is in a low power state (block 62). Specifically, the controller may determine that the gripper 23 is in an open position with the hinged arm 31 rotated (e.g., a threshold rotation distance) away from the blade 30. For example, the controller may determine that the ultrasonic instrument has received a user input (e.g., from the generator) to move the hinged arm 31 away from the blade 30. Specifically, the generator may provide the controller with an indication of the position of the hinged arm relative to the blade, and the controller may determine whether the end effector is open based on whether the distance between both arms is equal to or greater than the threshold distance. In another aspect, the generator may provide the controller with a status of the end effector based on the position of the hinged arm (e.g., whether the end effector is in an open position or a closed position). In another aspect, the controller may determine that the end effector is in an open position using one or more signal processing operations based on one or more characteristics of the end effector. For example, the controller may receive a characteristic such as a resonant frequency of the end effector from the generator and determine whether the end effector is open based on the resonant frequency. In one aspect, the determination may be based on performing a signal processing operation on a first derivative of the resonant frequency.

[0051] The controller determines (at block 63) a starting (or initial) resonant frequency of the end effector. Specifically, this may be a starting resonant frequency determined by (or in response to) the surgical system once the end effector of the instrument is in an open position (even while operating in a low power state). In one aspect, the controller may determine this starting resonant frequency of the blade 30 as the SRF after (e.g., shortly thereafter or within a time period) the controller determines that the end effector is in an open position. In one aspect, this starting frequency may be measured and provided by a generator, as described herein. The controller determines (at block 64) the difference between the starting resonant frequency and the baseline resonant frequency. Specifically, the controller determines the difference as follows: ΔSRF = SRF - RF (t0)

[0052] In one aspect, the difference ΔSRF represents the resonant frequency drift (or change therebetween) from the baseline (or nominal) resonant frequency of the blade to the starting resonant frequency. The controller 40 determines (at block 65) the heating duration that the ultrasonic instrument was in the high power state before switching to the low power state. Specifically, the controller determines the amount of time that the ultrasonic instrument was active (e.g., in the high power state) before operating in its current low power state. This heating duration (HD) may be expressed as: HD=t heating end -t heating start

[0053] In this formula, t heating end represents the time when the ultrasonic instrument switches to a low power state, and t heating start is another time that the ultrasonic instrument last entered a high power state. heating start t heating end It is an earlier time.

[0054] The controller determines (at block 66) a starting (initial) normalized change in resonant frequency. Specifically, this normalized change in frequency may be the average drift rate of the resonant frequency at the beginning when the ultrasonic instrument enters a low power state (e.g., the ultrasonic instrument begins its cooling cycle due to not drawing enough power to heat its end effector).

[0055]

number

[0056] The controller determines (at block 67) one or more model coefficients based on the starting normalized change in resonant frequency. In one aspect, each of the coefficients may be determined based on the normalized change in resonant frequency (e.g., determined in block 66). In one aspect, the number of coefficients determined may be based on the particular model that may be used by the controller to determine the temperature of the end effector. For example, if the model is a third order cooling polynomial model, the determined coefficients may include four coefficients (A, B, C, D) as follows: A=C 11 * ΔSRF NORM +C 12 B=C 21 * ΔSRF NORM +C 22 C=C 31 * ΔSRF NORM +C 32 D=C 41 * ΔSRF NORM +C 42

[0057] In one embodiment, eight constants C 11 ~C 42may be predefined in a controlled environment (e.g., a laboratory). For example, the constants may be defined by fitting the "normalized start resonant frequency" data to a third order polynomial observed while modeling on one or more tissues using one or more ultrasonic instruments. For example, a temperature sensor (e.g., a pyrometer) may be used to measure the temperature of the end effector during one or more heating cycles and one or more cooling cycles of the end effector. During these measurements, one or more characteristics of the ultrasonic instrument may be determined (e.g., by the generator) as described herein. For example, initially, the end effector is in a closed position to grasp a portion of tissue. The ultrasonic instrument may then be activated (e.g., by a user) such that the instrument is in a high power state for a controlled period of time (e.g., one second, etc.). The instrument is then switched to a low power state (e.g., the generator is switched on) to terminate the heating cycle, the end effector is placed in an open position, and the tissue is removed from the jaws of the end effector (e.g., the end effector may be moved away from the tissue). In one aspect, a cooling cycle may begin once the end effector is moved away from the tissue (e.g., such that the tissue is no longer in contact with the jaws of the grasper). In one aspect, depending on the type / thickness of the grasped tissue and the activation during the heating cycle, the peak temperature of the end effector (while the instrument is in a high power state) varies. The resonant frequency, ultrasonic instrument temperature data, and / or duration of the heating cycle may be determined during the cooling cycle and used to determine one or more of the constants. In some aspects, the determined constants may differ based on the ultrasonic instrument being used with the surgical system. In that case, the controller may be configured to determine the type of ultrasonic instrument coupled to the surgical system and to determine one or more of the constants based on the determined type.

[0058] As described herein, the model may be a third order cooling polynomial model including four coefficients. In another embodiment, the model may be a second order polynomial model, in which case the model may include the same or a different number of coefficients.

[0059] The controller 40 determines (at block 68) the normalized change in resonant frequency as a function of time. Specifically, after determining the starting resonant frequency, the controller may continue to determine the resonant frequency of the end effector. For example, the generator may provide one or more measured resonant frequencies of the blade of the end effector after the starting frequency. In one aspect, the controller may receive one or more (subsequent) measured resonant frequencies (e.g., every millisecond, second, minute, etc.). For each determined resonant frequency RF, the controller may determine the drift from the baseline as follows: ΔRF = RF - RF (t0)

[0060] The controller may determine a normalized change for all (or at least some) of the determined frequencies (e.g., if one or more of the resonant frequencies are determined after the starting resonant frequency) as a function of time, which may be defined as follows:

[0061]

number

[0062] In one aspect, this function may be determined from one or more of the determined resonant frequencies. The controller 40 may estimate (or determine) the temperature of the end effector by applying (at block 69) the normalized change in resonant frequency and one or more model coefficients as inputs to a predefined model that produces temperature as an output. In particular, the controller may define temperature as the following third order polynomial model, which is a function of time:

[0063]

number

[0064] Thus, the controller may determine the temperature of the blade of the end effector (e.g., at any given time) based on changes to the determined resonant frequency of the blade. Thus, by performing one or more of the temperature estimation operations described herein, the controller may determine (estimate) the temperature of the end effector based on one or more characteristics (e.g., resonant frequency) of the ultrasonic instrument without the use of (e.g., data from) a temperature sensor. In one aspect, the ultrasonic instrument may not include a temperature sensor.

[0065] The controller 40 is configured to output a notification based on the temperature (at block 70). For example, the controller may display a notification (e.g., a pop-up) on the display 15 of the surgical system 1 that includes the temperature of the end effector. In that case, the displayed notification may be a graphical user interface (GUI) item that is overlaid on a video and / or image being displayed on the display, such as an endoscopic video that may be provided by an endoscopic camera having a view of the surgical site (e.g., within the patient's abdomen). In another aspect, the notification may indicate the status of the end effector (e.g., "high temperature"). In another aspect, the system may output an audible notification via the speaker 43. For example, the audible notification may be one or more sounds (e.g., beeps) that indicate that the end effector has a temperature above a threshold. In another aspect, the audible notification may be spoken (e.g., "Caution! Blade is hot!"). In another aspect, any type of notification may be used.

[0066] In one aspect, the controller may perform one or more of these operations in real time such that the surgical system may estimate (e.g., continuously) and provide the temperature to an operator of the surgical system (e.g., while the ultrasonic instrument is in a low power state). In this case, the controller may continue to display the temperature of the end effector while the ultrasonic instrument is cooling. In some aspects, the system may cease providing a notification when the temperature of the end effector reaches a threshold. For example, the controller may determine whether the temperature is above a temperature threshold. In response to determining that the temperature is above the threshold, the controller may output a notification. However, if the temperature is below the threshold, the controller may cease outputting the notification, which may provide an indication to the operator that the end effector is no longer hot. In another aspect, the controller may output a notification that the end effector is no longer hot (e.g., by displaying a pop-up notification on the display such as "Blade is cold").

[0067] In some aspects, the controller may be configured to determine the time when the temperature of the end effector will be below the temperature threshold. For example, as described herein, the controller determines the temperature of the end effector based on a polynomial model (or a particular order) that is a function of time. The controller may then use the model to estimate when the blade will be below the temperature threshold based on the rate of change of temperature with respect to time. In another aspect, the controller may determine the time based on a change in a determined resonant frequency of the end effector. For example, the controller may receive one or more resonant frequencies following an initial resonant frequency while the ultrasonic instrument is in a low power state. The controller may determine the time when the temperature will be below the temperature threshold based on the rate of change of the subsequent (and initial) resonant frequencies. Once determined, the controller may be configured to include the time in a notification to provide an indication to the operator of when the end effector will be cool.

[0068] As described thus far, the surgical system is configured to determine the temperature of the ultrasonic instrument in order to output a notification, such as displaying the temperature on a display. This information can be used by the operator of the ultrasonic instrument (e.g., during a surgical procedure) to avoid using the instrument in contact with surrounding tissue while the blade is still hot. As a result, the operator can use this information to appropriately adjust how they operate the ultrasonic instrument (e.g., be more careful to avoid contact with tissue). In another aspect, this information can be used by the operator to continue to perform an ultrasonic surgical procedure. For example, with the end effector retaining residual heat from when the instrument was activated, the operator may continue to use the instrument to perform one or more operations, such as sealing a blood vessel. The operator may then use the displayed temperature while the instrument is in a low power state (e.g., without having to reactivate the instrument) to determine whether to continue using the instrument (e.g., based on whether the temperature of the end effector is hot enough to continue sealing a blood vessel).

[0069] Some embodiments may make one or more variations to the process 60 described herein. For example, certain operations of the process may not be performed in the exact order shown and described. Certain operations may not be performed in one continuous series of operations, and different certain operations may be performed in different embodiments. As described herein, the process determines that the end effector is in an open position at block 62. In some embodiments, the controller may wait to perform subsequent operations (e.g., 63-70) until the end effector is in this position. In that case, these operations of process 60 may be performed some time after the ultrasonic instrument switches to a low power state. This may be because the operator of the surgical instrument maintains the end effector in a closed position for some time while the instrument is in the low power state. In another embodiment, at least some of these operations may be performed every time the ultrasonic instrument is activated (e.g., operating in a high power state). For example, the controller may determine (eg, at block 67) one or more new model coefficients such that a new temperature estimation model is created after each activation of the ultrasonic instrument.

[0070] As described herein, the controller is configured to determine one or more model coefficients and estimate the temperature by applying the normalized change in resonant frequency and the coefficients to a predefined model. In one aspect, the controller may be configured to determine the model based on an ultrasonic instrument. Specifically, the model may be based on one or more physical characteristics of the instrument, such as the mechanical structure of the end effector of the instrument. In some aspects, at least some of these physical characteristics may vary between different ultrasonic instruments (e.g., when the blades between the instruments are of different sizes / shapes). The difference in physical characteristics may result in different models for the instruments. For example, if the model is a polynomial model, the order of the model (e.g., quadratic or cubic) may be based on the physical characteristics of the particular instrument. In one aspect, the number of model coefficients may also be based on the characteristics of the instrument. In that case, the controller may be configured to determine the ultrasonic instruments (of one or more instruments) that are part of the surgical system (e.g., coupled to the generator 25) and determine the model (e.g., the order of the polynomial model) associated with the determined instrument. In one aspect, this determination may be a table lookup into a data structure (having tables) that associates different types of ultrasonic instruments with one or more models (and / or model coefficients).

[0071] FIG. 6 illustrates several stages of a display of a surgical system illustrating actions taken by an end effector of an ultrasonic instrument and illustrating notifications based on a determined temperature of the end effector. Specifically, each of the three stages 70-72 illustrates a display 15 of a surgical system displaying an endoscopic video 73. The video, which may be provided by one or more endoscopic cameras of the system 1, illustrates a surgical site within a patient where a surgical procedure is being performed. In particular, the video 73 illustrates tissue 74 (e.g., a blood vessel) being manipulated by the end effector 23. In another aspect, the display may show other content, such as other video content and / or a graphical user interface (GUI) of the surgical system displaying one or more UI items.

[0072] A first stage 70 shows the end effector 23 grasping (a portion of) tissue 74. In particular, the grasper is positioned such that the tissue is disposed between the hinged arm 31 and the blade 30, and the hinged arm is moved toward the blade 30 such that the tissue is sandwiched (e.g., in contact) between both arms. In addition, the ultrasonic instrument of the end effector 23 is being used to perform an ultrasonic instrument action on the tissue. In particular, the ultrasonic instrument may be in a high power state in which it is vibrating while the end effector is in contact with the tissue 74, thereby generating frictional heat to cut and seal the tissue.

[0073] The second stage 71 shows the result of cutting and sealing the tissue with the end effector. As shown, the tissue has been cut into two pieces by the end effector and has also been cauterized. In addition, the grasper is now in an open position (hinged arm 31 has been moved away from the blade). Once the tissue is cut, the operator may no longer need to heat the end effector, and therefore the instrument may switch from a high power state to a low power state to enter a cooling cycle, as described herein. Thus, at this stage, the ultrasonic instrument may be provided with a current (e.g., by generator 25) that is below a current threshold at which the instrument creates (e.g., frictional) heat in the blade. In addition, (the controller 40 of) the surgical system may estimate the temperature of the blade based on the resonant frequency of the blade while the current is provided to the instrument, as described herein. In one aspect, the controller may perform at least some of the operations described herein to estimate the temperature.

[0074] A third step 72 shows that a notification 75 is displayed as a graphical user interface (GUI) item overlaid on top of the endoscopic video 73. The notification is based on the estimated temperature of the blade. In particular, the notification includes the text "WARNING! BLADE IS HOT!" to alert the operator of the blade's temperature condition. In another aspect, the notification may exist separately from the (e.g., other) video and / or images displayed on the display 15. In one aspect, the surgical system may continue to determine the blade temperature and display the notification while the blade is cooling. In some aspects, when the blade is below the temperature threshold, the surgical system may remove the notification and indicate to the operator that the blade is no longer hot.

[0075] As described herein, the display 15 is configured to present the endoscopic video 73 and notifications. In one embodiment, the generator's display 24 may display the video and / or notifications. For example, the display 24 may present the endoscopic video and notifications, or may display notifications while the system's display 15 displays the endoscopic video.

[0076] 7 is a flow diagram of a process 50 for an embodiment for determining the temperature of the end effector. Notably, at least some of the operations in this process may be performed by the controller 40 of the surgical system. In another embodiment, at least some of the operations may be performed in the generator 25. The process 50 begins with the controller 40 determining (at block 81) that the ultrasonic instrument 20 is in a low power state. Specifically, the controller determines that the ultrasonic instrument is not drawing enough power (e.g., not enough current is being provided by the generator 25) to heat the end effector 23 of the ultrasonic instrument (e.g., while the end effector is in contact with tissue). In one embodiment, the controller may receive an indication from the generator that it is providing less power (or is in a low power state). In another embodiment, the controller may receive an indication that the operator of the surgical system no longer wishes to actively use the instrument (e.g., based on user input) to perform a heat-related surgical task (e.g., cutting, cauterizing, etc.).

[0077] The controller determines (at block 82) a resonant frequency of the end effector. The controller determines (at block 83) a temperature of the end effector based on the resonant frequency. In particular, the controller may perform one or more of the operations of process 60 described in FIG. 5 to determine the resonant frequency and temperature. The controller displays (at block 84) a notification based on the temperature on a display of the surgical system. For example, the notification may include the temperature of the end effector, as described herein, and / or may include a textual indication that the blade is hot.

[0078] Some aspects may make variations to the processes 60 and / or 80 described herein. For example, at least some of the specific operations of the processes may not be performed in the exact order shown and described. Certain operations may not be performed in one continuous series of operations, and different specific operations may be performed in different aspects. For example, the controller may determine the resonant frequency and temperature while the ultrasonic instrument is in a low power state. In another embodiment, at least some of these operations may be performed after the ultrasonic instrument is in a high power state. For example, the controller may determine that the ultrasonic instrument is in a high power state in which the instrument is drawing power (e.g., from the generator 25) to heat its end effector 23. For example, the controller may receive an indication from the generator that the instrument is providing current to the instrument (e.g., based on user input) to vibrate the end effector through a range of motion that results in the generation of frictional heat when the instrument contacts an object. Thus, the ultrasonic instrument may be active, enabling an operator of the surgical system to perform one or more ultrasonic instrument operations (e.g., cutting, sealing, etc.). The controller may switch the ultrasonic instrument to a low power state based on one or more conditions being met, such as receiving an indication (e.g., based on user input) that an operator of the surgical system no longer wishes to actively use the instrument. Once the ultrasonic instrument switches to a low power state, at least some of the operations described herein may be performed to determine and display the temperature of its end effector.

[0079] As described herein, the ultrasonic instrument 20 may be a laparoscopic instrument held and manipulated by an operator. In another embodiment, the instrument may be part of a surgical robotic arm. For example, the ultrasonic instrument may be coupled to the distal end of a robotic arm, such as arm 4 of FIG. 1, and movement and manipulation of the ultrasonic instrument may be performed via one or more user controls (e.g., UID, foot pedal, etc.) coupled to the surgical system. In some embodiments, the ultrasonic instrument may be coupled to the arm and controlled by the generator based on user input. For example, the generator may control the rotational position of the hinged arm 31 to open and close the grasper 23 based on user input via one or more user input devices, such as UID 14, communicatively coupled to the generator, as described herein. In another aspect, the generator may adjust the spatial position (e.g., in space) of the end effector based on user input (e.g., based on the position of the UID). In another aspect, the spatial and / or rotational position of the hinged arm may be controlled by the controller 40 (e.g., based on user input received by the controller).

[0080] As described herein, the surgical system is configured to estimate the temperature of the ultrasonic instrument while the instrument is in a low power state. In one aspect, the system may estimate this temperature based on user input. For example, the system may perform these estimation operations while the instrument is in this state and when an operator of the ultrasonic instrument is not actively using the instrument (e.g., to cut and / or seal tissue). Specifically, these operations may be performed during the cool-down cycle of the instrument. In another aspect, at least some of these operations may be performed while the instrument is actively being used to perform ultrasonic instrument operations. In particular, the controller 40 may perform closed-loop temperature control operations to maintain a particular end effector temperature while the operator is actively using the instrument. For example, the controller may estimate the temperature of the end effector while the end effector is actively being used by the operator (e.g., while the instrument is in a high power state and while the blade of the end effector is generating heat due to friction between the blade and tissue being grasped by the end effector). In one aspect, the controller may estimate this "high state" temperature using any known method of estimating temperature while the ultrasonic instrument is in a heating cycle (e.g., Adaptive Tissue Technology (ATT), Controlled Thermal Management (CTM), etc.). The controller may compare this high state temperature to a temperature threshold. Upon determining that the high state temperature is at or above the temperature threshold (e.g., by a threshold amount), the controller may be configured to switch the ultrasonic instrument to a low power state. Upon switching to the low power state, the controller may continue to estimate the (e.g., "low state") temperature of the blade using one or more operations described herein. Upon determining that the low state temperature is below the temperature threshold (or below this threshold by a threshold amount), the controller may be configured to restart the ultrasonic instrument. Thus, the surgical system may adjust the current supplied to the ultrasonic instrument to maintain the temperature of the end effector.

[0081] As previously explained, aspects of the present disclosure may be a non-transitory machine-readable medium (such as a microelectronic memory) having instructions stored thereon that program one or more data processing components (collectively referred to herein as a "processor") to (automatically) perform the ultrasonic instrument operations and / or temperature estimation operations described herein. In other aspects, some of these operations may be performed by specific hardware components that include hardwired logic. These operations may alternatively be performed by any combination of programmed data processing components and fixed hardwired circuitry components.

[0082] While particular embodiments have been described and illustrated in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of the broad disclosure and are not limiting of the broad disclosure, and since various other modifications may occur to those skilled in the art, the disclosure is not limited to the specific construction and arrangements shown and described. Thus, the description should be regarded as illustrative instead of restrictive.

[0083] In some aspects, the disclosure may include a style such as, for example, "at least one of [element A] and [element B]." This style may refer to one or more of the elements. For example, "at least one of A and B" may refer to "A," "B," or "A and B." Specifically, "at least one of A and B" may refer to "at least one of A and at least one of B," or "at least one of A or B." In some aspects, the disclosure may include a style such as, for example, "[element A], [element B], and / or [element C]." This style may refer to any of the elements or any combination thereof. For example, "A, B, and / or C" may refer to "A," "B," "C," "A and B," "A and C," "B and C," or "A, B, and C."

[0084] [Embodiment] (1) A method performed by a surgical system, the method comprising: determining that the ultrasonic instrument is in a low power state; determining a resonant frequency of an end effector of the ultrasonic instrument; determining a temperature of the end effector based on the resonant frequency; and and displaying the temperature-based notification on a display of the surgical system. (2) The method of claim 1, wherein the end effector is a gripper, the gripper comprising: 1) a blade, the blade oscillating along a longitudinal axis of the blade; and 2) a hinged jaw rotatably coupled to a joint of the gripper. (3) The method of claim 2, wherein the blade vibrates through a first range of motion while the ultrasonic instrument is in a high power state, and while the ultrasonic instrument is in the low power state, the ultrasonic instrument draws less power to vibrate the blade through a second range of motion that is smaller than the first range of motion. (4) The method of claim 2, further comprising determining that the gripper is in an open position with the hinged jaw rotated away from the blade, and the resonant frequency is determined in response to determining that the gripper is in the open position. (5) The method of claim 1, further comprising determining a baseline resonant frequency of the end effector during initial power-on of the ultrasonic instrument, and the temperature of the end effector is determined based on a difference between the baseline resonant frequency and the resonant frequency.

[0085] (6) The method of embodiment 5, further comprising determining a heating duration during which the ultrasonic instrument was in a high power state before being in the low power state, and determining the temperature of the end effector comprises applying the heating duration and the difference as inputs to a predefined model that generates the temperature as an output. (7) The method of claim 1, wherein the notification includes the determined temperature of the end effector. (8) The resonant frequency is a first resonant frequency, and the method further comprises: determining a second subsequent resonant frequency of the end effector while the ultrasonic instrument is in the low power state; determining a time at which the temperature of the end effector will fall below a threshold based on a rate of change between the first resonant frequency and the second resonant frequency; 2. The method of claim 1, wherein the notification includes the time. (9) determining whether the temperature is above a threshold; and The method of embodiment 1, further comprising, in response to determining that the temperature is above the threshold, performing at least one of: 1) displaying the notification including text indicating that the temperature is high; and 2) outputting an output alert audio indicating that the temperature is high via one or more speakers of the surgical system. (10) A surgical system comprising: an ultrasonic instrument having an end effector; A display and A processor; a memory that, when executed by the processor, provides the surgical system with: determining that the ultrasonic instrument is in a low power state; determining a resonant frequency of the end effector; determining a temperature of the end effector based on the received resonant frequency; A surgical system comprising: a memory having instructions for causing a notification based on the temperature to be displayed on the display.

[0086] (11) The surgical system of claim 10, wherein the end effector is a grasper comprising: 1) a blade, the blade oscillating along a longitudinal axis of the blade; and 2) a hinged jaw rotatably coupled to a joint of the grasper. (12) The surgical system of claim 11, wherein the blade oscillates through a first range of motion while the ultrasonic instrument is in a high power state, and while the ultrasonic instrument is in the low power state, the ultrasonic instrument draws less power to oscillate the blade through a second range of motion that is smaller than the first range of motion. (13) The surgical system of claim 11, wherein the memory has a further means for determining that the grasper is in an open position with the hinged jaw rotated away from the blade, and the resonant frequency is determined in response to determining that the grasper is in the open position. (14) The surgical system of claim 10, wherein the memory has further instructions for determining a baseline resonant frequency of the end effector during initial power-on of the ultrasonic instrument, and the temperature of the end effector is determined based on a difference between the baseline resonant frequency and the resonant frequency. (15) The surgical system of claim 14, wherein the memory has further instructions for determining the heating duration the ultrasonic instrument was in a high power state before being in the low power state, and the instructions for determining the temperature of the end effector include instructions for applying the heating duration and the difference as inputs to a predefined model that generates the temperature as an output.

[0087] (16) A surgical system as described in embodiment 10, wherein the notification includes the determined temperature of the end effector. (17) The resonant frequency is a first resonant frequency, and the memory determining a second subsequent resonant frequency of the end effector while the ultrasonic instrument is in the low power state; determining a time when the temperature of the end effector will be below a threshold based on a rate of change between the first resonant frequency and the second resonant frequency; A surgical system as described in embodiment 10, wherein the notification includes the time. (18) The memory includes: determining whether the temperature is above a threshold; The surgical system of embodiment 10, further having instructions for, in response to determining that the temperature is above the threshold, to at least one of: 1) displaying a notification including text indicating that the temperature is high; and 2) outputting an audio alert indicating that the temperature is high via one or more speakers of the surgical system. (19) A method performed by a surgical system, the method comprising: providing an ultrasonic instrument with a current below a current threshold at which the instrument generates heat in a blade of the instrument; estimating a temperature of the blade based on a resonant frequency of the blade while the current is provided to the ultrasonic instrument; and displaying, on a display, a notification based on the estimated temperature of the blade. (20) The method of claim 19, wherein the temperature of the blade is estimated without the use of a temperature sensor.

[0088] (21) The method of claim 19, wherein the blade is configured to vibrate along a longitudinal axis of the blade to generate the heat, the blade being part of a gripper of the ultrasonic instrument, the gripper also having a hinged arm arranged to rotate about an axis transverse to the longitudinal axis. (22) The method of claim 21, further comprising determining that the gripper is in an open position with the hinged arm rotated away from the blade, and wherein the temperature is estimated in response to determining that the gripper is in the open position. (23) The method of embodiment 21, further comprising displaying on the display an endoscopic video of a surgical site within a patient where a surgical procedure is being performed, and the notification is a graphical user interface (GUI) item overlaid on the endoscopic video.

Claims

1. 1. A surgical system comprising: an ultrasonic instrument having an end effector; The display and a processor; a memory that, when executed by the processor, causes the surgical system to: providing a current to the ultrasonic instrument to place the ultrasonic instrument in a low power state, the current being below a current threshold at which the end effector generates heat; While the ultrasonic instrument is in the low power state: determining a resonant frequency of the end effector; determining a temperature of the end effector based on the resonant frequency; and displaying a notification based on the temperature on the display.

2. 2. The surgical system of claim 1, wherein the end effector is a grasper comprising: 1) a blade that oscillates along a longitudinal axis of the blade; and 2) a hinged jaw rotatably coupled to a joint of the grasper.

3. 3. The surgical system of claim 2, wherein the blade oscillates through a first range of motion while the ultrasonic instrument is in a high power state, and wherein while the ultrasonic instrument is in the low power state, the ultrasonic instrument draws less power to oscillate the blade through a second range of motion that is smaller than the first range of motion.

4. 3. The surgical system of claim 2, wherein the memory comprises a further means for determining that the grasper is in an open position with the hinged jaw rotated away from the blade, and the resonant frequency is determined in response to determining that the grasper is in the open position.

5. 2. The surgical system of claim 1, wherein the memory further comprises instructions for determining a baseline resonant frequency of the end effector during initial power-up of the ultrasonic instrument, and the temperature of the end effector is determined based on a difference between the baseline resonant frequency and the resonant frequency.

6. 6. The surgical system of claim 5, wherein the memory further has instructions for determining a heating duration the ultrasonic instrument was in a high power state before being in the low power state, and wherein the instructions for determining the temperature of the end effector include instructions for using a predefined temperature model to output the temperature in response to inputs based on the heating duration and the difference between the baseline resonant frequency and the resonant frequency.

7. The surgical system of claim 1 , wherein the notification includes the determined temperature of the end effector.

8. The resonant frequency is a first resonant frequency, and the memory determining a subsequent, second resonant frequency of the end effector while the ultrasonic instrument is in the low power state; determining a time when the temperature of the end effector will be below a threshold based on a rate of change between the first resonant frequency and the second resonant frequency; The surgical system of claim 1 , wherein the notification includes the time.

9. The memory includes: determining whether the temperature is above a threshold; 10. The surgical system of claim 1, further comprising instructions for, in response to determining that the temperature is above the threshold, to at least one of: 1) displaying the notification including text indicating that the temperature is high; and 2) outputting an audio alert via one or more speakers of the surgical system indicating that the temperature is high.

10. 1. A method performed by a surgical system, the method comprising: providing an electric current to the ultrasonic instrument to place the ultrasonic instrument in a low power state, the electric current being below a current threshold that causes an end effector of the ultrasonic instrument to generate heat; While the ultrasonic instrument is in the low power state: determining a resonant frequency of the end effector of the ultrasonic instrument; determining a temperature of the end effector based on the resonant frequency; and displaying the temperature-based notification on a display of the surgical system.

11. 11. The method of claim 10, wherein the end effector is a grasper, the grasper comprising: 1) a blade that oscillates along a longitudinal axis of the blade; and 2) a hinged jaw rotatably coupled to a joint of the grasper.

12. 12. The method of claim 11, wherein the blade oscillates through a first range of motion while the ultrasonic instrument is in a high power state, and while the ultrasonic instrument is in the low power state, the ultrasonic instrument draws less power to oscillate the blade through a second range of motion that is smaller than the first range of motion.

13. 12. The method of claim 11, further comprising determining that the gripper is in an open position with the hinged jaws rotated away from the blade, and wherein the resonant frequency is determined in response to determining that the gripper is in the open position.

14. 11. The method of claim 10, further comprising determining a baseline resonant frequency of the end effector during initial power-up of the ultrasonic instrument, wherein the temperature of the end effector is determined based on a difference between the baseline resonant frequency and the resonant frequency.

15. 15. The method of claim 14, further comprising determining a heating duration the ultrasonic instrument was in a high power state before being in the low power state, and wherein determining the temperature of the end effector comprises using a predefined temperature model to output the temperature in response to inputs based on the heating duration and the difference between the baseline resonant frequency and the resonant frequency.

16. The method of claim 10, further comprising providing a subsequent current to the ultrasonic instrument that is greater than or equal to the current threshold to place the ultrasonic instrument in a high power state that causes the end effector to generate sufficient heat to cut or cauterize tissue.

17. the resonant frequency is a first resonant frequency, and the method includes: determining a subsequent, second resonant frequency of the end effector while the ultrasonic instrument is in the low power state; and determining a time at which the temperature of the end effector will fall below a threshold based on a rate of change between the first resonant frequency and the second resonant frequency; The method of claim 10 , wherein the notification includes the time.

18. determining whether the temperature is above a threshold; 11. The method of claim 10, further comprising, in response to determining that the temperature is above the threshold, performing at least one of: 1) displaying the notification including text indicating that the temperature is high; and 2) outputting an audio alert via one or more speakers of the surgical system indicating that the temperature is high.

19. 1. A method performed by a surgical system, the method comprising: providing an ultrasonic instrument with a current below a current threshold at which the instrument generates heat in a blade of the instrument; estimating a temperature of the blade based on a resonant frequency of the blade while the current is provided to the ultrasonic instrument; and displaying, on a display, a notification based on the estimated temperature of the blade.

20. The method of claim 19 , wherein the temperature of the blade is estimated without the use of a temperature sensor.

21. 20. The method of claim 19, wherein the blade is configured to vibrate along a longitudinal axis of the blade to generate the heat, and the blade is part of a gripper of the ultrasonic instrument, the gripper also having a hinged arm arranged to rotate about an axis transverse to the longitudinal axis.

22. 22. The method of claim 21, further comprising determining that the gripper is in an open position with the hinged arm rotated away from the blade, and wherein the temperature is estimated in response to determining that the gripper is in the open position.

23. 22. The method of claim 21, further comprising displaying on the display an endoscopic video of a surgical site within a patient where a surgical procedure is being performed, and wherein the notification is a graphical user interface (GUI) item overlaid on the endoscopic video.

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