Spring assisted sealing instrument

Abstract

A surgical instrument includes a housing having a shaft extending therefrom, the shaft having an end effector at a distal end thereof. The end effector includes a first jaw member and a second jaw member movable between a spaced apart configuration and a closed position to grasp tissue between the jaw members. A drive assembly including a drive lever is associated with the movable jaw member. A spring having a spring stiffness factor is operably associated with the drive rod and is configured to unload a force associated with the drive rod during actuation of the drive rod. The spring includes a first length at which adjacent windings of the spring are spaced apart from each other by a distance such that the spring unloads a force associated with the drive rod according to a spring stiffness coefficient "k" of the spring, and a fully compressed length at which adjacent windings of the spring abut each other such that the spring unloads the force associated with the drive rod according to a spring stiffness coefficient "k" of the spring. And the force associated with the drive rod is transmitted through the spring.

Description

Technical Field

[0001] The present disclosure relates to surgical instruments and, more particularly, to sealing instruments and related methods, such as for use in robotic surgical systems. Background Art

[0002] Surgical systems are increasingly being used in a variety of different surgical procedures. For example, a robotic surgical system includes a console that supports a robotic arm. One or more different surgical instruments may be configured for use with the robotic surgical system and may be selectively mounted to the robotic arm. The robotic arm provides one or more inputs to the mounted surgical instrument to enable operation of the mounted surgical instrument.

[0003] When treating tissue, it may be necessary to control the closing force and sealing force between the jaw members of the surgical instrument to properly treat the tissue and avoid tissue and / or instrument damage. Therefore, instrument manufacturers are generally required to include a way to monitor the force on the tissue or other aspects of the surgical instrument during treatment. Summary of the invention

[0004] As used herein, the term "distal" refers to the portion of the description that is farther from the operator (whether a surgeon or a surgical robot), while the term "proximal" refers to the portion of the description that is closer to the operator. As used herein, the terms "approximately," "substantially," and the like are intended to take into account manufacturing, material, environmental, usage, and / or measurement tolerances and variations. In addition, to the extent consistent, any aspect described herein may be used in combination with any or all other aspects described herein. In addition, rotation may be measured in degrees or radians.

[0005] According to aspects of the present disclosure, a surgical instrument is provided, the surgical instrument comprising a housing having a shaft extending therefrom, the shaft comprising an end effector at its distal end, the end effector comprising a first jaw member and a second jaw member. One or both of the jaw members can be moved between a spaced configuration relative to the other jaw member and a closed position, in which the jaw members cooperate to grasp tissue therebetween. A drive assembly including a drive rod is operably associated with the one or more jaw members and can be actuated to move the one or more jaw members between the spaced position and the closed position. A spring having a spring stiffness coefficient "k" is operably associated with the drive rod and is configured to unload the force associated with the drive rod during actuation of the drive rod. The spring comprises a first length and a fully compressed length, at which adjacent coils of the spring are spaced apart from each other by a distance so that the spring unloads the force associated with the drive rod according to the spring stiffness coefficient "k" of the spring, and at the fully compressed length, adjacent coils of the spring are adjacent to each other and the force associated with the drive rod is transmitted through the spring.

[0006] In aspects according to the present disclosure, the spring is configured to unload a specific percentage of the force associated with the drive rod before reaching a fully compressed length. In other aspects according to the present disclosure, the percentage of force unloaded to the drive rod is in the range of about 30% to about 80%.

[0007] In aspects according to the present disclosure, in the fully compressed length, force from an input operably associated with the drive assembly is directly transmitted to the drive rod. In other aspects according to the present disclosure, the input is operably associated with the drive assembly and includes an input connector from a robotic surgical system. In still other aspects according to the present disclosure, the input operably associated with the drive assembly includes a movable handle extending from the housing.

[0008] According to aspects of the present disclosure, there is provided a surgical instrument comprising a housing having a shaft extending therefrom, the shaft comprising an end effector at its distal end, the end effector comprising a first jaw member and a second jaw member. A drive assembly comprising: a drive rod operably associated with the one or more jaw members and actuatable to move the one or more jaw members between a spaced apart position and a closed position; and a progressive spring operably associated with the drive rod and comprising a variable spring rate "k", the progressive spring being configured to unload forces associated with the drive rod during actuation of the drive rod, the spring comprising a first spring rate "k1" associated with its initial activation and one or more different spring rates "k2" when the spring is compressed.

[0009] In aspects according to the present disclosure, the first spring rate "k1" is less than the at least one different spring rate "k2".

[0010] In aspects according to the present disclosure, the diameter of the progressive spring varies along its length. In other aspects according to the present disclosure, the spring rate of the progressive spring is directly proportional to its diameter.

[0011] In aspects according to the present disclosure, the spring rate of the progressive spring is non-linear.

[0012] According to aspects of the present disclosure, a surgical instrument is provided, the surgical instrument including a housing having a shaft extending therefrom, the shaft including an end effector at its distal end, the end effector including a first jaw member and a second jaw member. One or both of the jaw members are movable between a spaced apart configuration relative to the other jaw member and a closed position, in which the jaw members cooperate to grasp tissue therebetween. A drive assembly is included having a drive rod operably associated with the one or more jaw members and actuatable to move the one or more jaw members between the spaced apart position and the closed position to grasp tissue.

[0013] A cutter tube is disposed within the shaft, the cutter tube having a cutter at a distal end thereof, the cutter being configured to cut tissue disposed between the jaw members. A spring having a spring rate "k" is operably associated with the cutter tube and is configured to unload forces associated with the cutter tube during actuation of the cutter tube. The spring includes a first length, at the first length, adjacent coils of the spring are spaced a distance from one another such that the spring unloads forces associated with the cutter tube according to the spring rate "k" of the spring, and a fully compressed length, at the fully compressed length, adjacent coils of the spring abut one another and forces associated with the cutter tube are transmitted through the spring to prevent damage to the cutter.

[0014] In aspects according to the present disclosure, the spring is configured to unload a certain percentage of the force associated with the cutter tube before reaching a fully compressed length.

[0015] In aspects according to the present disclosure, an input coupling from a robotic surgical system is configured to actuate the cutter tube. In other aspects according to the present disclosure, a trigger is operably associated with the cutter tube and is configured to actuate the cutter tube when the trigger is moved.

[0016] In aspects according to the present disclosure, the instrument further includes a second spring operably associated with the cutter tube, the second spring configured to unload forces associated with articulation of the shaft and the cutter tube disposed therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various aspects and features of the present disclosure are described hereinafter with reference to the drawings, wherein like reference numerals designate identical or corresponding elements in each of the several views.

[0018] Figure 1A is a perspective view of a robotic surgical instrument configured to be mounted on a robotic arm of a robotic surgical system according to the present disclosure;

[0019] Figure 1Bis a stereoscopic view of an endoscopic surgical instrument provided according to the present disclosure;

[0020] Figure 2A yes Figure 1A A front perspective view of a proximal portion of a surgical instrument with a housing removed;

[0021] Figure 2B yes Figure 1A A rear perspective view of a proximal portion of the surgical instrument with the housing removed;

[0022] Figure 3 yes Figure 1A A front perspective view of a proximal portion of a surgical instrument with a housing and additional internal components removed;

[0023] Figure 4 is configured to releasably receive Figure 1A Schematic representation of an exemplary robotic surgical system with surgical instruments;

[0024] Figure 5 yes Figure 1A A front perspective view of a jaw drive subassembly of a surgical instrument;

[0025] Figure 6 yes Figure 1A A rear perspective view of a jaw drive subassembly of a surgical instrument;

[0026] Figure 7 yes Figure 1A An exploded perspective view of a jaw drive subassembly of a surgical instrument;

[0027] Figure 8 yes Figure 1A a perspective view of a distal portion of a surgical instrument with the end effector assembly arranged in an open position;

[0028] Fig. 9 yes Figure 1A A longitudinal cross-sectional view of a proximal portion of a surgical instrument showing the jaw drive subassembly transitioning the end effector assembly from an open position toward a closed position;

[0029] Fig.10 yes Figure 1A a perspective view of a distal portion of a surgical instrument of , wherein the end effector assembly is arranged in a closed position;

[0030] Fig.11 yes Figure 1A A longitudinal cross-sectional view of a proximal portion of a surgical instrument showing the jaw drive subassembly retaining the end effector assembly in a closed position;

[0031] FIG. 12A to FIG. 12Cis an enlarged view of a spring according to one embodiment of the present disclosure, the spring being used with Figure 1A and Figure 1B Use with surgical instruments;

[0032] Fig.13A and Fig. 13B 1 and 10 are enlarged views of a linear spring and a progressive spring according to another embodiment of the present disclosure, the linear spring and the progressive spring being used with Figure 1A and Figure 1B Use with surgical instruments;

[0033] Fig. 13C It shows Fig.13A and 13B a graph of the corresponding different spring rates for the springs shown; and

[0034] Fig.14A and 14B is an enlarged view of a cutter tube for use with a load cell or one or more springs to prevent damage to the cutter tube according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] See also Figure 1A as well as Figures 2A to 3 The surgical instrument 10 provided according to the present disclosure generally includes a housing 20, a shaft 30 extending distally from the housing 20, an end effector assembly 40 extending distally from the shaft 30, and an actuation assembly 100 disposed within the housing 20 and operably associated with the end effector assembly 40. The instrument 10 is described herein as being configured for use with a robotic surgical system (e.g., robotic surgical system 2000 ( Figure 4 However, the aspects and features of the instrument 10 provided according to the present disclosure and described in detail below are also applicable for use with other suitable surgical instruments (e.g., graspers, staplers, clip appliers) and / or in other suitable surgical systems (e.g., motorized or other powered drive systems).

[0036] See Figure 1A The housing 20 of the device 10 includes a first body portion 22a and a second body portion 22b, and a proximal panel 24 that cooperate to enclose the actuation assembly 100 therein. The proximal panel 24 includes a hole defined therein, and the input connectors 110-140 ( Figure 2B ) extend through these holes. A pair of latch levers 26 ( Figure 1A Only one of them is shown in FIG. 2 ) enables the housing 20 to be used with a surgical system, such as a robotic surgical system 2000 ( Figure 4) is releasably engaged with a robotic arm of the housing 20. Aperture 28 defined through the housing 20 permits the thumb wheel 440 to extend therethrough to enable manual manipulation of the thumb wheel 440 from outside the housing 20, thereby permitting manual opening and closing of the end effector assembly 40.

[0037] refer to Figure 1B , an endoscopic electrosurgical clamp provided in accordance with the present disclosure is generally indicated by reference numeral 1000. Aspects and features of the clamp 10 that are not germane to an understanding of the present disclosure are omitted to avoid obscuring the aspects and features of the present disclosure with unnecessary detail.

[0038] The clamp 1000 includes a housing 1020, a handle assembly 1030, a trigger assembly 1060, a rotation assembly 1070, an activation switch 1080, and an end effector assembly 1100. The clamp 1010 further includes a shaft 1012 having a distal portion 1014 configured to (directly or indirectly) engage the end effector assembly 1100 and a proximal portion 1016 that (directly or indirectly) engages the housing 1020. The clamp 1000 also includes a cable "C" that connects the clamp 1000 to an energy source (e.g., an electrosurgical generator "G"). The cable "C" includes (one or more) wires (not shown) extending therethrough, the wires having a sufficient length to extend through the shaft 1012 so as to be connected to one or both of the tissue processing surfaces 1114, 1124 of the jaw members 1110, 1120 of the end effector assembly 1100, respectively, to provide energy thereto. The first activation switch 1080 is coupled to the tissue treatment surfaces 1114, 1124 and the electrosurgical generator "G" to enable selective activation of energy supply to the jaw members 1110, 1120 to treat (e.g., cauterize, coagulate / desiccate, and / or seal) tissue.

[0039] The handle assembly 1030 of the clamp 1000 includes a fixed handle 1050 and a movable handle 1040. The fixed handle 1050 is integrally connected to the housing 1020, and the handle 1040 is movable relative to the fixed handle 1050. The movable handle 1040 of the handle assembly 1030 is operably connected to a drive assembly (not shown), and the movable handle and the drive assembly mechanically cooperate together to move one or both of the jaw members 1110, 1120 of the end effector assembly 1100 around the pivot 1103 between a spaced apart position and a close position to grasp tissue between the tissue processing surfaces 1114, 1124 of the jaw members 1110, 1120. Figure 1BAs shown, the movable handle 1040 is initially spaced apart from the fixed handle 1050, and correspondingly, the jaw members 1110, 1120 of the end effector assembly 1100 are arranged in a spaced apart position. The movable handle 1040 can be depressed from the initial position to a depressed position corresponding to the close position of the jaw members 1110, 1120. The rotation assembly 1070 includes a rotation wheel 1072 that can be selectively rotated in either direction to correspondingly rotate the end effector assembly 1100 relative to the housing 1020.

[0040] Return to see Figures 2A to 3 , a plurality of electrical contacts 90 extend through one or more holes defined in the proximal panel 24 to engage the instrument 10 in the robotic surgical system 2000 ( Figure 4 ) to enable electrical communication between the instrument 10 and the robotic surgical system, thereby, for example, enabling communication of data, control and / or power signals therebetween. As an alternative to the electrical contacts 90 extending through the proximal panel 24, other suitable transmitter, receiver and / or transceiver components capable of communicating data, control and / or power signals are also contemplated, such as by using RFID, Or via any other suitable wired, wireless, contact or contactless communication method. Wherein at least some of the electrical contacts 90 are electrically connected to an electronic device 92 mounted on the inner side of the proximal panel 24, such as in the housing 20. The electronic device 92 may include, for example, a storage device, a communication device (including suitable input / output components), and a CPU including a memory and a processor. The electronic device 92 may be mounted on a circuit board or configured in other ways, such as as a chip.

[0041] The storage device of the electronic device 92 stores information related to the surgical instrument, such as: a product number, such as a SKU number; a manufacturing date; a manufacturing location, such as a location code; a serial number; a batch number; usage information; setting information; adjustment information; calibration information; security information such as an encryption key, and / or other suitable additional or alternative data. The storage device of the electronic device 92 can be, for example, a magnetic disk, a flash memory, an optical disk, or other suitable data storage device.

[0042] Instead of or in addition to storing the above information in a storage device of the electronic device 92, some or all of such information (e.g., usage information, calibration information, setup information, and / or adjustment information) may be stored in a computer associated with the robotic surgical system 2000 ( Figure 4 ), a remote server, a cloud server, etc. and can be connected via the instrument 10 and / or the robotic surgery system 2000 ( Figure 4) in a storage device accessible by the manufacturer. In such a configuration, the information may be updated, for example, by updates provided by the manufacturer, and / or may be applied to individual instruments, instrument units (e.g., units from the same manufacturing location, manufacturing cycle, batch number, etc.), or to all instruments. Still further, even where the information is stored locally on each instrument, the information may also be available to the user when connected to the robotic surgical system 2000 ( Figure 4 ) manually or automatically through updates provided by the manufacturer.

[0043] Reference again Figure 1A , the shaft 30 of the instrument 10 accordingly includes a distal segment 32, a proximal segment 34, and an articulation segment 36 disposed between the distal segment 32 and the proximal segment 34. The articulation segment 36 includes one or more articulation components 37, such as links, joints, etc. A plurality of articulation cables 38 (e.g., four (4) articulation cables) or other suitable actuators extend through the articulation segment 36. More specifically, the articulation cable 38 is operably coupled at its distal end to the distal segment 32 of the shaft 30 and extends proximally from the distal segment 32 of the shaft 30, through the articulation section 36 of the shaft 30 and the proximal segment 34 of the shaft 30, and into the housing 20, wherein the articulation cable 38 is operably coupled to the articulation subassembly 200 of the actuation assembly 100 to enable the distal segment 32 (and thus the end effector assembly 40) to selectively articulate relative to the proximal segment 34 and the housing 20, for example, about at least two axes of articulation (e.g., yaw and pitch articulation). The articulation cable 38 is arranged in a generally rectangular configuration, but other suitable configurations are also contemplated. In some configurations, as an alternative, the shaft 30 is substantially rigid, ductile, or flexible and is not configured for active articulation.

[0044] With respect to articulation of the end effector assembly 40 relative to the proximal segment 34 of the shaft 30, actuation of the articulation cables 38 may be accomplished in pairs. More specifically, to pitch the end effector assembly 40, the upper pair of cables 38 is actuated in a similar manner, while the lower pair of cables 38 is actuated in a manner similar to each other but opposite to the upper pair of cables 38. With respect to yaw articulation, the right pair of cables 38 is actuated in a similar manner, while the left pair of cables 38 is actuated in a manner similar to each other but opposite to the right pair of cables 38. Other configurations of articulation cables 38 or other articulation actuators are also contemplated.

[0045] Continue to refer Figure 1AThe end effector assembly 40 includes a first jaw member 42 and a second jaw member 44. Each jaw member 42, 44 includes a proximal flange portion 43a, 45a and a distal body portion 43b, 45b. The distal body portions 43b, 45b define opposing tissue contact surfaces 46, 48, respectively. The proximal flange portions 43a, 45a are pivotally coupled to each other about a pivot axis 50 and are operably coupled to each other via a cam slot assembly 52 (the cam slot assembly includes a cam pin slidably received in a cam slot defined in a corresponding proximal flange portion 43a, 45a of at least one of the jaw members 42, 44) to enable the jaw member 42 to pivot relative to the jaw member 44 and the distal segment 32 of the shaft 30 between a spaced-apart position (e.g., an open position of the end effector assembly 40) and a close position (e.g., a closed position of the end effector assembly 40) to grasp tissue "T" ( Figure 8 and Fig.10 As an alternative to this single-sided configuration, a double-sided configuration may be provided in which the two jaw members 42, 44 are pivotable relative to each other and relative to the distal section 32 of the shaft 30. Other suitable jaw actuation mechanisms are also contemplated.

[0046] In various configurations, a longitudinally extending knife channel 49 is shown defined by the tissue contacting surfaces 46, 48 of one or both jaw members 42, 44 (only the knife channel 49 of the jaw member 44 is shown; the knife channel of the jaw member 42 is similarly configured). In such an embodiment, a knife assembly is provided that includes a knife tube 62 ( Figure 6 ) and a blade 315 disposed within the end effector assembly 40 between the jaw members 42, 44. The blade 315 can be selectively translated through the (multiple) knife channels 49 and between the jaw members 42, 44 to cut tissue "T" ( Figure 8 and Fig.10 The cutter tube 62 is operably coupled at its proximal end to the actuation assembly 100 ( FIG. 2A to FIG. 2B ) of the tool drive subassembly 300 ( Figure 3 ) so that the cutter tube 62 can be selectively actuated to reciprocate the blade 315 between the jaw members 42, 44 to cut the tissue "T" ( Figure 8 and Fig.10 As an alternative to the longitudinally advanceable mechanical knife, other suitable mechanical cutters are also contemplated, such as guillotine cutters, and energy-based cutters, such as RF electrical cutters, ultrasonic cutters, etc., in static or dynamic configurations.

[0047] Still reference Figure 1A , the drive rod 484 is operably connected to the cam slot assembly 52 of the end effector assembly 40, for example, engaged with its cam pin, so that longitudinal actuation of the drive rod 484 causes the jaw member 42 to pivot relative to the jaw member 44 between the spaced position and the close position. More specifically, pushing the drive rod 484 proximally causes the jaw member 42 to pivot relative to the jaw member 44 toward the close position, while pushing the drive rod 484 distally causes the jaw member 42 to pivot relative to the jaw member 44 toward the spaced position. However, other suitable mechanisms and / or configurations for pivoting the jaw member 42 relative to the jaw member 44 between the spaced position and the close position in response to selective actuation of the drive rod 484 are also contemplated. The drive rod 484 extends proximally from the end effector assembly 40 through the shaft 30 and into the housing 20, wherein the drive rod 484 is coupled to the actuation assembly 100 ( FIG. 2A to FIG. 2B ) of the jaw drive subassembly 400 is operably coupled to enable the end effector assembly 40 to be selectively actuated to grasp tissue "T" therebetween ( Figure 8 and Fig.10 ), and applying a jaw force within an appropriate jaw force range, as described in detail below.

[0048] The tissue contacting surfaces 46, 48 of the jaw members 42, 44 are respectively formed at least in part of a conductive material and can be energized to different electrical potentials to enable RF electrical energy to be conducted through the tissue "T" ( Figure 8 and Fig.10 ), but tissue contacting surfaces 46, 48 may alternatively be configured to supply any suitable energy such as heat, microwaves, light, ultrasound, ultrasonic waves, etc. through the tissue "T" ( Figure 8 and Fig.10 ) for energy-based tissue treatment. The instrument 10 defines a conductive pathway (not shown) through the housing 20 and the shaft 30 to the end effector assembly 40, which may include wires, contacts and / or conductive components to enable the tissue contacting surfaces 46, 48 of the jaw members 42, 44 to be electrically connected to an energy source (not shown), such as an electrosurgical generator, for supplying energy to the tissue contacting surfaces 46, 48 to treat (e.g., seal) the tissue "T" ( Figure 8 and Fig.10 ).

[0049] See also Figures 2A to 3As described above, the actuation assembly 100 is disposed in the housing 20 and includes an articulation subassembly 200, a tool drive subassembly 300, and a jaw drive subassembly 400. The articulation subassembly 200 is operably coupled between the first input connector 110 and the second input connector 120 of the actuation assembly 100 and the articulation cable 38 ( Figure 1A ) so that upon receiving appropriate input in the first input coupling 110 and / or the second input coupling 120, the articulation subassembly 200 manipulates the cable 38 ( Figure 1A ) to cause the end effector assembly 40 to articulate in a desired direction, such as causing the end effector assembly 40 to pitch and / or yaw.

[0050] The knife drive subassembly 300 is operably coupled between the third input coupling 130 of the actuation assembly 100 and the knife tube such that upon receiving an appropriate input in the third input coupling 130, the knife drive subassembly 300 manipulates the knife tube to reciprocate the blade 315 between the jaw members 42, 44, thereby cutting tissue "T" ( Figure 8 and Fig.10 ).

[0051] The jaw drive subassembly 400 (as described in detail below) is operably coupled between the fourth input coupling 140 of the actuation assembly 100 and the drive rod 484 such that upon receipt of an appropriate input into the fourth input coupling 140, the jaw drive subassembly 400 pivots the jaw members 42, 44 between the spaced apart position and the approximated position to grasp tissue "T" therebetween. Figure 8 and Fig.10 ) and applies a jaw force within the appropriate jaw force range.

[0052] The actuation assembly 100 is configured to be actuated when the instrument 10 is mounted on the robotic surgical system 2000 ( Figure 4 ) and Robotic Surgery System 2000( Figure 4 ) are operably docked to enable robotic operation of the actuation assembly 100 to provide the functions detailed above. That is, the robotic surgical system 2000 ( Figure 4 ) selectively provides input, such as rotational input, to the input couplings 110-140 of the actuation assembly 100 to cause the end effector assembly 40 to articulate and grasp tissue "T" between the jaw members 42, 44 ( Figure 8 and Fig.10 ) and / or cutting of tissue "T" ( Figure 8 and Fig.10However, it is also contemplated that the actuation assembly 100 is configured to interface with any other suitable surgical system (e.g., a manual surgical handle, an electric surgical handle, etc.). For the purposes of this document, the robotic surgical system 2000 ( Figure 4 ).

[0053] Steering Figure 4 , the robotic surgery system 2000 is configured for use in accordance with the present disclosure. Aspects and features of the robotic surgery system 2000 that are not germane to an understanding of the present disclosure are omitted to avoid obscuring the aspects and features of the present disclosure with unnecessary detail.

[0054] The robotic surgery system 2000 generally includes: a plurality of robotic arms 2002, 2003; a control device 2004; and an operation console 2005, which is connected to the control device 2004. The operation console 2005 may include: a display device 2006, which may be configured to display a three-dimensional image in particular; and manual input devices 2007, 2008, by which a surgeon or the like may be able to remotely manipulate the robotic arms 2002, 2003 in a first operation mode. The robotic surgery system 2000 may be configured for a patient 2013 lying on a patient table 2012 to be treated in a minimally invasive manner. The robotic surgery system 2000 may further include a database 2014, which is specifically connected to the control device 2004, in which, for example, preoperative data and / or anatomical atlases of the patient 2013 are stored.

[0055] Each of the robotic arms 2002, 2003 may include a plurality of components connected by joints, and mounted devices which may be, for example, surgical tools "ST". One or more of the surgical tools "ST" may be instrument 10 ( Figure 1A ), thereby providing such functionality on the robotic surgery system 2000.

[0056] The robotic arms 2002, 2003 may be driven by an electric drive device, such as a motor, connected to the control device 2004. For example, the motor may be a rotary drive motor configured to provide a rotary input, such as to selectively rotate and drive a surgical instrument ( Figure 1A ) of the input connector 110-140 ( Figure 2B) to complete one or more desired tasks. The control device 2004 (e.g., a computer) can be configured to activate the motors in a manner, particularly through a computer program, that is, to cause the robotic arms 2002, 2003 and therefore their mounted surgical tools "ST" to perform desired movements and / or functions according to corresponding inputs from the manual input devices 2007, 2008, respectively. The control device 2004 can also be configured in a manner that causes it to regulate the movement of the robotic arms 2002, 2003 and / or the motors.

[0057] More specifically, the control device 2004 can control one or more of the motors based on rotation, for example, using a rotational position encoder (or Hall effect sensor or other suitable rotational position detector) associated with the motor to control the rotational position to determine the degree of rotation output from the motor and, therefore, the degree of rotation provided to the surgical instrument 10 ( Figure 1A ) of the corresponding input connectors 110-140 ( Figure 2B ) of the rotational input degrees. Alternatively or additionally, the control device 2004 can control one or more of the motors based on torque, current, or in any other suitable manner.

[0058] See also Figures 5 to 7 , the jaw drive subassembly 400 of the actuation assembly 100 is generally shown to include an input shaft 410 , an input gear 420 , a drive gear 430 , a thumb wheel 440 , a spring force assembly 450 , and a drive rod assembly 480 .

[0059] The input shaft 410 includes a proximal portion 412 operably coupled to the fourth input coupling 140, and a distal portion 414 on which the input gear 420 is engaged, such that a rotational input provided to the fourth input coupling 140 drives rotation of the input shaft 410, thereby driving rotation of the input gear 420. The input gear 420 is arranged to mesh with the rounded gear 432 of the drive gear 430, such that rotation of the input gear 420, for example, in response to the rotational input provided at the fourth input coupling 140, causes the drive gear 430 to rotate in the opposite direction. The thumb wheel 440 is also arranged to mesh with the rounded gear 432 of the drive gear 430, such that rotation of the thumb wheel 440 causes the drive gear 430 to rotate in the opposite direction, so that the drive gear 430 can be manually driven via manipulation of the thumb wheel 440. The drive gear 430 (in addition to the rounded gear 432 ) further includes a lead screw 434 fixedly engaged with (eg, integrally formed with) the rounded gear 432 , such that rotation of the rounded gear 432 causes similar rotation of the lead screw 434 .

[0060] The spring force assembly 450 includes a proximal hub 452 , a distal hub 454 , a compression spring 456 , and a spring washer 458 , although suitable force limiting assemblies are also contemplated, such as utilizing torsion springs, compliance features, etc. The spring force assembly 450 further includes a pair of guide rods 470 .

[0061] The proximal hub 452 and the distal hub 454 of the spring force assembly 450 can be the same component that is oriented, positioned, and / or coupled to other components in different ways to provide different functions while reducing the number of different components that need to be manufactured. The features of the proximal hub 452 and the distal hub 454 are detailed below to the extent necessary to facilitate understanding of the present disclosure, and therefore, although some features may be detailed only with respect to one of the proximal hub 452 or the distal hub 454 and the functions associated therewith, similar features may be provided on the other of the proximal hub 452 or the distal hub 454 without the associated functions. Alternatively, the proximal hub 452 and the distal hub 454 can be manufactured as different components.

[0062] The proximal hub 452 and the distal hub 454 of the spring force assembly 450 each include a retainer guide 463 extending radially outward from opposite sides thereof. Each retainer guide 463 defines a slot 464 and includes a shoulder 465 extending into the corresponding slot 464. The proximal hub 452 and the distal hub 454 are oriented relative to each other such that the open ends of the cavities defined therein face each other and such that the shoulders 465 of each pair of retainer guides 463 of the proximal hub 452 and the distal hub 454 face away from each other.

[0063] The proximal hub 452 further includes a transverse slot 466 defined therethrough that is configured to receive a locking plate 482 of the drive rod assembly 480 to secure the locking plate 482, and thereby secure the proximal end portion of the drive rod 484 relative to the proximal hub 452 (see Fig. 9 and Fig.11 Once engaged in this manner, the drive rod 484 is locked in a position coaxially arranged through the proximal hub 452, the distal hub 454, the compression spring 456 and the drive gear 430.

[0064] The distal hub 454 defines a threaded central bore 468 extending therethrough. The threaded central bore 468 receives the lead screw 434 of the drive gear 430 therethrough in threaded engagement therewith, such that rotation of the lead screw 434 drives the distal hub 454 to translate longitudinally along the lead screw 434.

[0065] A compression spring 456 is disposed between the proximal hub 452 and the distal hub 454, with a proximal portion of the compression spring disposed within a cavity defined within the proximal hub 452 and a distal portion of the compression spring disposed within a cavity defined within the distal hub 462. At least a portion of the compression spring 456 is disposed around and / or configured to receive a portion of the lead screw 434 of the drive gear 430 therethrough. A spring washer 458 is positioned within the cavity of the proximal hub 452, between the proximal hub 452 and the compression spring 456, although other configurations are also contemplated.

[0066] Each guide bar 470 is slidably received within a slot 464 of a corresponding pair of retainer guides 463 of the proximal hub 452 and the distal hub 454. Each guide bar 470 includes a pair of spaced rims 472, 474 engaged thereon that are configured to abut a shoulder 465 of a corresponding retainer guide 463, thereby defining a maximum distance between the proximal hub 452 and the distal hub 454. However, the proximal hub 452 and / or the distal hub 454 are permitted to slide toward each other along the guide bar 470, as described in detail below.

[0067] Continue to see Figures 5 to 7 , the drive rod assembly 480 includes a locking plate 482 and a drive rod 484. The locking plate 482 defines a central key hole 485 and a pair of slots 486 (e.g., arcuate slots) defined on the distal side of the locking plate 482 on either side of the central key hole 485. The locking plate 482 is configured to be inserted through the transverse slot 466 of the proximal hub 452, and once installed therein, a portion of the spring washer 458 is configured to be received in the slot 486 to securely engage the locking plate 482 in the proximal hub 452. The spring washer 458 is maintained in position in the slot 486 under the bias of the compression spring 456, which is pre-compressed at the maximum distance between the proximal hub 452 and the distal hub 454 (set by the rims 472, 474 of the guide rod 470 and the shoulder 465 of the retainer guide 463).

[0068] As described above, the drive rod 484 includes a distal portion of the cam slot assembly 52 operably coupled to the end effector assembly 40 ( FIG. 1 ). The drive rod 484 extends proximally through the shaft 30, the housing 20, and the actuation assembly 100 (see FIG. 1 ). Figure 1A , Figures 2A to 3) and engaged within the locking plate 482 at the proximal end portion of the drive rod 484. More specifically, the drive rod 484 defines a waist 488 toward its proximal end that is configured to be lockingly engaged within the central keyhole 485, such as via longitudinal translation of the drive rod 484 into the central keyhole 485 until the waist 488 is aligned with the central keyhole 485 of the locking plate 482, followed by lateral movement of the drive rod 484 relative to the locking plate 482, thereby fixing the proximal end portion of the drive rod 484 relative to the locking plate 482 and, therefore, relative to the proximal hub 452 due to the engagement of the locking plate 482 within the proximal hub 452.

[0069] See also Figures 8 to 11 In use, the jaw members 42, 44 are initially arranged in a spaced apart position ( Figure 8 ), and correspondingly, the proximal hub 452 and the distal hub 454 are arranged in the most distal position, so that the drive rod 484 is arranged in the most distal position ( Fig. 9 ). In addition, in this position, the compression spring 456 is arranged to be in a minimum compression state; however, as described above, even in the minimum compression state, the compression spring 456 is partially compressed because the compression spring 456 is maintained in a pre-compressed configuration between the proximal hub 452 and the distal hub 454.

[0070] In response to an input to close the end effector assembly 40, for example, the robotic surgical system 2000 ( Figure 4 ) of the corresponding motor to the fourth input connector 140 ( Figures 5 to 7 ), the drive shaft 410 rotates to thereby rotate the input gear 420, which in turn rotates the drive gear 430, thereby causing the distal hub 454 to translate proximally toward the proximal hub 452 (see Fig. 9 ). The proximal translation of the distal hub 454 pushes the distal hub 454 against the compression spring 456. Initially, when the force resisting the close proximity of the jaw members 42, 44 is below a threshold value corresponding to the spring value of the compression spring 456, the jaw force applied by the jaw members 42, 44 is relatively low, so that the proximal push of the distal hub 454 against the compression spring 456 pushes the compression spring 456 proximally, which in turn pushes the locking plate 482 and thus the drive rod 484 proximally to pivot the jaw member 42 relative to the jaw member 44 from the spaced-apart position toward the close position, thereby grasping the tissue "T" ( Figure 8 and Fig.10 ).

[0071] When the jaw members 42 and 44 are further approached to grasp the tissue "T" therebetween, the force used to resist the approach of the jaw members 42 and 44 (e.g., the tissue "T" resists compression) can reach a threshold value, so the jaw force applied by the jaw members 42 and 44 can reach a corresponding threshold value. In order to maintain the jaw force applied by the jaw members 42 and 44 within the jaw force range, for example, from about 3 kg / cm 2 About 16kg / cm 2 , exceeding the threshold point inhibits the clamping members 42, 44 from applying further clamping force despite further rotational input to the fourth input coupling 140 ( Figures 5 to 7 More specifically, once the threshold is reached, the fourth input connector 140 ( Figures 5 to 7 ) further rotational input rotates the drive shaft 410, the input gear 420 and the drive gear 430, thereby causing the distal hub 454 to translate further proximally into the compression spring 456. However, rather than the compression spring 456 pushing the proximal hub 452 further proximally to continue to approach the jaw members 42, 44 and increase the closing force applied therebetween, the compression spring 456 is compressed, allowing the proximal hub 452 and therefore the drive rod 484 to remain in place, thereby inhibiting the application of additional jaw force between the jaw members 42, 44 (see Fig.10 and Fig.11 ).

[0072] When the tissue "T" is grasped between the jaw members 42, 44 under appropriate jaw force, energy can be supplied to the jaw members 42, 44 to process (e.g., seal) the tissue "T". Thereafter, the blade 315 can be advanced between the jaw members 42, 44 to cut the processed tissue "T", for example, by applying force to the input coupling 130 ( Figure 6 ) provides a rotational input to actuate the knife drive subassembly 300 to translate the knife tube distally, thereby advancing the blade 315 between the jaw members 42, 44 to cut the treated tissue "T". Alternatively, the tissue "T" may be cut without first treating the tissue "T", and / or the tissue "T" may be treated without subsequent cutting.

[0073] Once the tissue "T" is cut, the input coupling 130 ( Figure 6 ) provides an opposite rotational input to return the blade 315 to its initial position, that is, between the body portions 43b, 45b of the jaw members 42, 44 (see Figure 1A ) near the side. Thereafter, to the input connector 140 ( Figures 5 to 7 ) provides an opposite input to return the jaw members 42, 44 toward the spaced-apart position to release the sealed and / or cut tissue.

[0074] See in general Figure 1A , Figures 2A to 11 As described above, calibration information, setup information, usage information, and adjustment information, as well as other information, are stored in a storage device of the electronic device 92 of the instrument 10, in the robotic surgical system 2000 ( Figure 4 ), and / or in other accessible storage devices. The calibration information may include algorithm(s), set point(s), lookup table(s), machine learning program(s), and / or other information capable of determining the original / initial positions of various components of the instrument 10, such as: the open position of the jaw members 42, 44, the retracted position of the blade 315, the unarticulated kinematic configuration of the shaft 30 and end effector assembly 40, etc.

[0075] The setup information may include, for example, jaw drive information, such as the degree of rotational input required to the input connector 140 in order to move the jaw members 42, 44 from the open position toward the closed position to grasp the tissue "T" between the tissue contact surfaces 46, 48 and apply a jaw force or a jaw force within the jaw force range; tool deployment information, such as the degree of rotational input required to the input connector 130 in order to deploy the blade 315 from the retracted position to the extended position to cut the tissue "T" between the tissue contact surfaces 46, 48; and / or articulation control information, such as the degree of rotational input required to the input connectors 110 and / or 120 in order to articulate the end effector assembly 40 from a non-articulated motion position to one or more articulated motion positions (e.g., a maximum positive swing position, a maximum negative swing position, a maximum positive pitch position, and a maximum negative pitch position); and the like. The setting information can be determined based on testing during manufacturing (e.g., for each instrument, each instrument unit, or for all instruments), can be determined via mathematical simulation, utilizing machine learning, using theoretical formulas, combinations thereof, and the like.

[0076] The usage information may include, for example, the number of connections to the robotic surgical system, elapsed time of use / connection, elapsed idle time, elapsed time of active use, age (time since manufacture), number of jaw member approximations, number of energy activations, number and / or pattern of articulation movements, number of blade 315 deployments, etc. The robotic surgical system 2000 may write and / or update the usage information stored in the storage device 92 of the instrument 10 (and / or elsewhere) periodically, continuously, after an event occurs, or in any other suitable manner.

[0077] Some or all of the setting information may be basic information that may be adjusted periodically, continuously, upon occurrence of a particular event, and / or based on external input (user-provided input, sensor or other component feedback, etc.). For example, the basic setting information may be adjusted, for example, at the robotic surgical system 2000, based on one or more current conditions and / or current usage information of the instrument 10, as indicated by the adjustment information. The adjustment information for each corresponding setting may include algorithm(s), set point(s), lookup table(s), machine learning program(s), etc. The adjustment information may be experimentally determined via mathematical simulation, using machine learning, using theoretical formulas, combinations thereof, etc.

[0078] For example, the jaw drive setting information may provide basic information to indicate that the rotational input degree "X" to be given to the input coupling 140 is required to move the jaw members 42, 44 from the open position toward the closed position to grasp the tissue "T" between the tissue contacting surfaces 46, 48 and apply a jaw force or a jaw force within the jaw force range thereto. Therefore, without modifying this jaw drive setting information, upon receiving a signal to bring the jaw members 42, 44 closer together to grasp the tissue between the tissue contacting surfaces 46, 48 for tissue treatment (e.g., sealing), the control device 2004 controls the appropriate motor(s) of the robotic surgical system 2000 to apply the rotational input degree "X" to the input coupling 140 so that the tissue contacting surfaces 46, 48 grasp the tissue "T" therebetween under the action of the applied jaw force or the jaw force within the jaw force range.

[0079] However, it has been discovered that the jaw force or jaw force range applied in response to input of a set rotational input degree to input coupling 140 may vary over the useful life of instrument 10 and / or based on the current condition of instrument 10 (e.g., whether end effector assembly 40 is disposed in an unarticulated position, a partially articulated position, or a fully articulated position). The stage of useful life of instrument 10 may be determined based on some or all of the above-described usage information, and the jaw force or jaw force range may be affected by factors such as changes in component stiffness / elasticity, establishment of a "memory" position of a component / connection, changes in force transmission across a joint / connection, changes in tolerances, changes in friction losses, component wear, degradation of components and / or joints / connections, etc. The current condition of instrument 10 may be determined by control device 1004 and / or other components of robotic surgical system 2000 based on feedback data, prior input, visual or other tracking information, etc., and the jaw force or jaw force range may be affected by changes in actuation force, changes in actuation distance, changes in friction, etc.

[0080] To account for the above changes, the adjustment information enables the basic jaw actuation setting (e.g., "X" degrees) to be adjusted to an adjusted jaw actuation setting (e.g., "Y" degrees) based on the use and / or current conditions of the instrument 10 by using algorithm(s), set point(s), lookup table(s), machine learning program(s), etc. Thus, with the adjusted jaw actuation setting information implemented, upon receiving a signal to bring the jaw members 42, 44 closer together to grasp tissue between the tissue contacting surfaces 46, 48 for tissue treatment (e.g., sealing), the control device 1004 controls the appropriate motor(s) of the robotic surgical system 2000 to apply a rotational input degree "Y" to the input coupling 140 such that the tissue contacting surfaces 46, 48 grasp tissue "T" therebetween at the applied jaw force or jaw force within the jaw force range. Thus, despite the changed input requirements, the same jaw force or jaw force range can be achieved.

[0081] However, the present disclosure is not limited to adjusting the jaw drive setting information for applying the jaw force, but can be applied to adjusting any other suitable setting information, such as tool deployment information, articulation motion control information, etc. Further, the present disclosure is not limited to the instrument 10, but can also be applied to any other suitable surgical instrument. In fact, the method provided according to the present disclosure and described in detail below with reference to Figures 12 and 13 can be used with the instrument 10 to adjust the jaw drive setting information, or can be used with any other suitable instrument and / or its desired manipulation.

[0082] Now go to FIG. 12A to FIG. 14B Various embodiments of the present disclosure utilize one or more springs in conjunction with a sealing device to change, modify, and / or adjust the pressure load between the jaw members 42, 44 during sealing or in some cases as a safety measure. For example, Fig. 12A Shown for use with Figure 1A The drive assembly 450 is used together with a spring 1456, wherein the spring 1456 can be x Under the action of the first length L0 to the fully compressed length L g It is important to note that other mechanisms of the apparatus 10 that employ a spring may be configured to utilize FIG. 12A to FIG. 14B Describes features such as knife spring, return spring, etc.

[0083] More specifically, in the initial state in which the jaw members 42, 44 are fully opened, the spring 1456 is arranged as follows: Fig. 12AThe spring 1456 is shown in a fully expanded state (although it is contemplated that the spring 1456 may be preloaded under slight compression to reduce "sloshing"). In this state, adjacent coils 1456a, 1456b are spaced or "separated" from each other by a distance C1 at the compression rate or "spring rate" k of the spring. Upon actuation of the input coupling 140, the spring 1456 is compressed an initial distance such that the coils 1456a, 1456b are closed by the force F as described above for closing the jaw members 42, 44 around tissue. x The separation distance C2 is under the action of.

[0084] Fig. 12C The spring 1456 is shown in full compression (e.g., solid length), wherein the coils 1456a, 1456b are substantially touching or "coil stacked." It is contemplated that the coil stacking position of the spring 1456 can be used for additional purposes, such as providing a direct or firm drive force from the motor (or handle) to the jaw members 42, 44 without the assistance of the spring, or in other embodiments, providing feedback to the robotic system 2000, such as safety information, such as a warning of excessive tissue compression. More specifically, the spring 1456 can be configured such that a certain percentage (e.g., 60%) of the travel of the input coupling will produce a force F on the tissue that is offset by the spring rate of the spring 1456. x When the spring 1456 is fully compressed as Fig. 12C In the coil stack configuration shown, the spring 1456 becomes a substantially solid structure, thereby transferring the force F from the drive assembly 450 and the input coupling 140 to the input coupling 140. x directly to the jaw members 42, 44 and the tissue. As a result, the force on the tissue can vary during the travel of the drive assembly 450. As can be appreciated, this is particularly advantageous for handheld instruments, i.e., initial handle movement for manipulating and operating tissue under slight to full compression when sealing tissue. In an embodiment, the spring 1456 can be configured to offset from about 30% to about 80% of the force associated with the input control on the drive assembly 450 or the drive rod 484, depending on the particular purpose.

[0085] As mentioned above, Fig. 12C The coil stacking configuration of spring 1456 shown in FIG. 14 can be used to warn the surgeon if tissue is being over-compressed. In other words, a sensor (not shown) can be used to warn the surgeon that the spring coils 1456a, 1456b are in contact, so that further drive input (or Figure 1BFurther handle compression of the handheld instrument) may result in over-compression of the tissue. Alternatively, the overlapping contact of the coils of spring coils 1456a, 1456b can simply alert the user to the change in compressive force on the tissue, for example, from being controlled by the spring rate of spring 1456 to a direct input force from the coupling 140 (or handle 1030).

[0086] FIG. 13A to FIG. 13C Another embodiment of the present disclosure is shown, wherein the spring may have a variable or progressive spring rate during compression (or extension). More particularly, Fig.13A The spring 2456a is a linear spring in which the spring constant k is constant during travel (i.e., compression or extension) or is in a state such as Fig. 13C The linear stiffness coefficient is shown in the graph. Variable or progressive spring 2456b ( Fig. 13B ) includes coils 2457a, 2457b of varying diameter which in turn vary the spring rate k during travel. Fig. 13C The graph of highlights the difference between the linear spring 2456a and the progressive spring 2456b. The diameter of the progressive spring 2456b at different points along the progressive spring 2456b can be mathematically related to its spring rate k.

[0087] The variable spring rate k of the progressive spring 2456b is configured to unload the forces associated with the drive rod during actuation of the drive rod 484; the spring includes a first spring rate "k1" associated with its initial activation and one or more different spring rates "k2" when the spring is compressed. In short, when the drive rod 484 is initially actuated, the spring rate k may not be very conducive to grasping and manipulating tissue. As the spring 2456b is compressed, the spring rate k increases toward the sealing force (see Fig. 13C ). Thus, the compressive force F on the tissue x will change during the travel of spring 2456b, that is, as spring 2456b is compressed, the rate of increase of force becomes greater.

[0088] In other embodiments, one or more springs may be used to warn the surgeon that a higher than expected force has been applied to a particular portion of the instrument (e.g., shaft, blade, etc.) or tissue via the jaw members 42, 44. More particularly, and similar to a fishing rod, a spring torque wrench (not shown) may be used to prevent excessive torque on one or more instrument components (e.g., drive rod 484). When the maximum allowable torque on the drive rod 484 (which is equivalent to the maximum allowable closing pressure) is reached, any additional torque on the drive rod 484 is dissipated by the spring torque wrench. Alternatively, and for the input coupling 140, when the maximum allowable torque on the drive rod 484 is reached, a switch may be activated to cut off further rotational input from the coupling 140, or a warning may be issued to the surgeon to release it to stop activation, or a spring torque wrench may also be used. As can be appreciated, this prevents excessive compression of tissue during sealing (or processing) and / or may be configured to prevent bending or breaking of the drive rod 484 or other driven components.

[0089] In an embodiment, a spring torque wrench can be applied to the articulation subassembly 200 to prevent excessive articulation of the distal segment 32 of the shaft 30 or the end effector 40, which may overstress other internal components. In addition, a spring torque wrench can be used with the cutter tube 62 to prevent damage to the cutter 315 when the cutter 315 encounters too thick tissue, bone or staples.

[0090] The spring may be configured to prevent damage to other component features, such as the cutter 315 . Fig. 14B An example of a pair of springs 3456a, 3456b disposed on either end of the tool tube 3062 is shown, which are configured to counteract the force F when a preset or preconfigured tolerance is applied. x . Force measuring element 3063( Fig.14A , Fig. 14B ) can be arranged on top of the cutter tube 3062 and configured to measure the strain (or stress) applied thereto during actuation of the cutter 315 (e.g., translation of the cutter tube 3062). The force measuring element 3063 is connected to a measuring device, a switch, an alarm, or the robotic surgery system 2000 to signal the user about the strain (or stress) on the cutter tube 3062. The springs 3456a, 3456b can be configured to unload the strain (or stress) on the cutter tube 3062 once a threshold is reached during actuation (e.g., translation of the cutter tube 3062) or articulation (bending) of the cutter tube 3062. The spring 3456b can also be used to cope with imperfect length variations along the cutter tube 3062.

[0091] Although several embodiments of the disclosure are shown in the accompanying drawings, it is not intended to limit the disclosure thereto, as it is intended that the scope of the disclosure be as wide as the art will allow, and this specification should be read in the same manner. Therefore, the above description should not be construed as limiting, but rather as merely exemplary of specific embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the appended claims.

[0092] It should be understood that various modifications may be made to the aspects and features disclosed herein. Therefore, the above description should not be understood as limiting, but rather as merely an example of a number of different aspects and features. Those skilled in the art will envision other modifications within the scope and spirit of the appended claims.

Claims

1. A surgical instrument, comprising: a housing including a shaft extending therefrom, the shaft having an end effector at a distal end thereof, the end effector including first and second jaw members, at least one of the jaw members being movable between a spaced apart position relative to the other jaw member and a closed position in which the jaw members cooperate to grasp tissue therebetween; as well as a drive assembly comprising: a drive rod operably associated with the at least one jaw member and actuatable to move the at least one jaw member between the spaced apart position and the closed position; and a spring having a spring rate "k", the spring being operably associated with the drive rod and being configured to unload forces associated therewith during actuation of the drive rod, the spring comprising at least a first length and a fully compressed length, wherein adjacent windings of the spring are spaced a distance relative to one another such that the spring unloads forces associated with the drive rod according to the spring rate "k" of the spring, and wherein adjacent windings of the spring abut one another and forces associated with the drive rod are transmitted through the spring.

2. The surgical instrument according to claim 1, wherein: The spring is configured to unload a certain percentage of the force associated with the drive rod before reaching a fully compressed length.

3. The surgical instrument according to claim 2, wherein: The percentage of force unloaded to the drive rod is in the range of about 30% to about 80%.

4. The surgical instrument according to claim 1, wherein: At the fully compressed length, force from an input operably associated with the drive assembly is transferred directly to the drive rod.

5. The surgical instrument according to claim 4, wherein: The input operably associated with the drive assembly includes an input coupling from a robotic surgical system.

6. The surgical instrument according to claim 4, wherein: The input operably associated with the drive assembly includes a movable handle extending from the housing.

7. A surgical instrument comprising: a housing including a shaft extending therefrom, the shaft having an end effector at a distal end thereof, the end effector including first and second jaw members, at least one of the jaw members being movable between a spaced-apart configuration relative to the other jaw member and a closed position in which the jaw members cooperate to grasp tissue therebetween; as well as A drive assembly, the drive assembly comprising: a drive rod operably associated with the at least one jaw member and actuatable to move the at least one jaw member between the spaced apart position and the closed position; as well as a progressive spring operably associated with the drive rod and having a variable spring rate "k", the progressive spring being configured to unload forces associated with the drive rod during actuation of the drive rod, the spring including a first spring rate "k1" associated with its initial activation and at least one different spring rate "k2" when the spring is compressed.

8. The surgical instrument according to claim 7, wherein: The first spring rate "k1" is less than the at least one different spring rate "k2".

9. The surgical instrument according to claim 7, wherein: The diameter of the progressive spring varies along its length.

10. The surgical instrument according to claim 9, wherein: The spring rate of the progressive rate spring is directly proportional to its diameter.

11. The surgical instrument according to claim 7, wherein: The spring rate of the progressive spring is non-linear.

12. A surgical instrument comprising: a housing including a shaft extending therefrom, the shaft having an end effector at a distal end thereof, the end effector including first and second jaw members, at least one of the jaw members being movable between a spaced-apart configuration relative to the other jaw member and a closed position in which the jaw members cooperate to grasp tissue therebetween; a drive assembly including a drive rod operably associated with the at least one jaw member and actuatable to move the at least one jaw member between the spaced apart position and the closed position to grasp tissue; a cutter tube disposed within the shaft, the cutter tube having a cutter at a distal end thereof, the cutter configured to cut tissue disposed between the jaw members; as well as A spring having a spring rate "k", the spring being operably associated with the cutter tube and being configured to unload forces associated therewith during actuation of the cutter tube, the spring comprising at least a first length and a fully compressed length, wherein adjacent windings of the spring are spaced a distance relative to one another so that the spring unloads forces associated with the cutter tube in accordance with the spring rate "k" of the spring, and wherein adjacent windings of the spring abut one another and forces associated with the cutter tube are transmitted through the spring to prevent damage to the cutter.

13. The surgical instrument according to claim 12, wherein: The spring is configured to unload a specific percentage of the force associated with the cutter tube before reaching a fully compressed length.

14. The surgical instrument according to claim 12, wherein: An input coupling from a robotic surgical system is configured to actuate the tool tube.

15. The surgical instrument according to claim 12, wherein: A trigger is operably associated with the cutter tube and is configured to actuate the cutter tube when the trigger is moved.

16. The surgical instrument of claim 12, further comprising a second spring operably associated with the cutter tube, the second spring configured to unload forces associated with articulation of the shaft and the cutter tube disposed therein.

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