Patent ID: 12239393

DETAILED DESCRIPTION

The embodiments described herein can advantageously be used in a wide variety of grasping, cutting, and manipulating operations associated with minimally invasive surgery. The medical instruments or devices of the present application enable motion in three or more degrees of freedom (DOFs). For example, in some embodiments, an end effector of the medical instrument can move with reference to the main body of the instrument in three mechanical DOFs, e.g., pitch, yaw, and roll (shaft roll). There may also be one or more mechanical DOFs in the end effector itself, e.g., two jaws, each rotating with reference to a clevis (2 DOFs) and a distal clevis that rotates with reference to a proximal clevis (one DOF). Thus, in some embodiments, the medical instruments or devices of the present application enable motion in six DOFs. The embodiments described herein further can be used to determine the forces exerted on (or by) a distal end portion of the instrument during use.

The medical instruments described herein include a force sensor unit having a cantilevered beam and one or more strain sensors on the beam. The medical devices include a hard stop structure that includes multiple opposing stop surfaces that can limit a range of motion of the beam when the opposing stop surfaces contact each other. For example, when a force imparted on a distal end of a medical instrument causes the distal end of the beam to bend or otherwise be displaced relative to a proximal end of the beam, the opposing stop surfaces of the hard stop structure can limit the range of motion of the beam. In some embodiments, the opposing stop surfaces of the hard stop structure can limit the range of motion of the beam in all directions of the lateral force imparted on a distal end portion of the medical instrument. In some embodiments, the hard stop structure includes a first set of stop surfaces and a second set of stop surfaces. In some embodiments, the first set of stop surfaces is disposed on the same side of the hard stop structure as the second set of stop surfaces. In some embodiments, the first set of stop surfaces is on an opposite side of the hard stop structure from the second set of stop surfaces.

In some embodiments, the hard stop structure includes multiple interlocking components that are formed by an opening cut into a wall of the hard stop structure. The interlocking components include multiple opposing stop surfaces as described above. In some embodiments, the opening in the hard stop structure (and interlocking components formed thereby) extend circumferentially around the hard stop structure in a spiral pattern. In some embodiments, the opening extends circumferentially around the wall of the hard stop structure by more than one revolution. In some embodiments, the opening extends circumferentially around the wall of the hard stop structure by at least two or more revolutions. In some embodiments, the hard stop structure is constructed of a stainless steel tube and the opening in the wall is laser cut.

The hard stop structure can be mounted to the same component of the medical instrument as the beam. The interlocking components formed by the opening defined in the wall of the hard stop structure enables the hard stop structure to bend flexibly to a relatively fixed preset angle or displacement. When the desired bend angle or displacement is reached, the interlocking components engage each other on at least one portion or one side of the hard stop structure and prevent the hard stop structure and the beam from bending further. For example, when the desired bend angle is reached, the opposing stop surfaces contact each other and prevent the hard stop structure and beam from bending further. In some embodiments, when the desired bend angle or displacement is reached, the interlocking components (i.e., the opposing stop surfaces of the interlocking components) prevent the hard stop structure and beam from bending or displacing further on both the compression side and the tension side of the hard stop structure and beam. Thus, in such an embodiment, the hard stop structure produces a reactive moment instead of a single reactive force once the hard stop engages.

As used herein, the term “about” when used in connection with a referenced numeric indication means the referenced numeric indication plus or minus up to 10 percent of that referenced numeric indication. For example, the language “about 50” covers the range of 45 to 55. Similarly, the language “about 5” covers the range of 4.5 to 5.5.

The term “flexible” in association with a part, such as a mechanical structure, component, or component assembly, should be broadly construed. In essence, the term means the part can be repeatedly bent and restored to an original shape without harm to the part. Certain flexible components can also be resilient. For example, a component (e.g., a flexure) is said to be resilient if possesses the ability to absorb energy when it is deformed elastically, and then release the stored energy upon unloading (i.e., returning to its original state). Many “rigid” objects have a slight inherent resilient “bendiness” due to material properties, although such objects are not considered “flexible” as the term is used herein.

As used in this specification and the appended claims, the word “distal” refers to direction towards a work site, and the word “proximal” refers to a direction away from the work site. Thus, for example, the end of a tool that is closest to the target tissue would be the distal end of the tool, and the end opposite the distal end (i.e., the end manipulated by the user or coupled to the actuation shaft) would be the proximal end of the tool.

Further, specific words chosen to describe one or more embodiments and optional elements or features are not intended to limit the invention. For example, spatially relative terms—such as “beneath”, “below”, “lower”, “above”, “upper”, “proximal”, “distal”, and the like—may be used to describe the relationship of one element or feature to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., translational placements) and orientations (i.e., rotational placements) of a device in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. Thus, the term “below” can encompass both positions and orientations of above and below. A device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Likewise, descriptions of movement along (translation) and around (rotation) various axes includes various spatial device positions and orientations. The combination of a body's position and orientation define the body's pose.

Similarly, geometric terms, such as “parallel”, “perpendicular”, “round”, or “square”, are not intended to require absolute mathematical precision, unless the context indicates otherwise. Instead, such geometric terms allow for variations due to manufacturing or equivalent functions. For example, if an element is described as “round” or “generally round,” a component that is not precisely circular (e.g., one that is slightly oblong or is a many-sided polygon) is still encompassed by this description.

In addition, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. The terms “comprises”, “includes”, “has”, and the like specify the presence of stated features, steps, operations, elements, components, etc. but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, or groups.

Unless indicated otherwise, the terms apparatus, medical device, instrument, and variants thereof, can be interchangeably used.

Aspects of the invention are described primarily in terms of an implementation using a da Vinci® Surgical System, commercialized by Intuitive Surgical, Inc. of Sunnyvale, California. such as, for example, the da Vinci Xi® Surgical System (Model IS4000), and the da Vinci X® Surgical System (Model IS4200). Knowledgeable persons will understand, however, that inventive aspects disclosed herein may be embodied and implemented in various ways, including computer-assisted, non-computer-assisted, and hybrid combinations of manual and computer-assisted embodiments and implementations. Implementations on da Vinci® Surgical Systems (e.g., the Model IS4000, the Model IS2000, the Model IS1200) are merely presented as examples, and they are not to be considered as limiting the scope of the inventive aspects disclosed herein. As applicable, inventive aspects may be embodied and implemented in both relatively smaller, hand-held, hand-operated devices and relatively larger systems that have additional mechanical support.

FIG.4is a plan view illustration of a computer-assisted teleoperation system. Shown is a medical device, which is a Minimally Invasive Robotic Surgical (MIRS) system1000(also referred to herein as a minimally invasive teleoperated surgery system), used for performing a minimally invasive diagnostic or surgical procedure on a Patient P who is lying on an Operating table1010. The system can have any number of components, such as a user control unit1100for use by a surgeon or other skilled clinician S during the procedure. The MIRS system1000can further include a manipulator unit1200(popularly referred to as a surgical robot), and an optional auxiliary equipment unit1150. The manipulator unit1200can include an arm assembly1300and a tool assembly removably coupled to the arm assembly. The manipulator unit1200can manipulate at least one removably coupled instruments1400through a minimally invasive incision in the body or natural orifice of the patient P while the surgeon S views the surgical site and controls movement of the instrument1400through control unit1100. An image of the surgical site is obtained by an endoscope (not shown), such as a stereoscopic endoscope, which can be manipulated by the manipulator unit1200to orient the endoscope. The auxiliary equipment unit1150can be used to process the images of the surgical site for subsequent display to the Surgeon S through the user control unit1100. The number of instruments1400used at one time will generally depend on the diagnostic or surgical procedure and the space constraints within the operating room, among other factors. If it is necessary to change one or more of the instruments1400being used during a procedure, an assistant removes the instrument1400from the manipulator unit1200and replaces it with another instrument1400from a tray1020in the operating room. Although shown as being used with the instruments1400, any of the instruments described herein can be used with the MIRS1000.

FIG.5is a perspective view of the control unit1100. The user control unit1100includes a left eye display1112and a right eye display1114for presenting the surgeon S with a coordinated stereo view of the surgical site that enables depth perception. The user control unit1100further includes one or more input control devices1116, which in turn cause the manipulator unit1200(shown inFIG.4) to manipulate one or more tools. The input control devices1116provide at least the same degrees of freedom as instruments1400with which they are associated to provide the surgeon S with telepresence, or the perception that the input control devices1116are integral with (or are directly connected to) the instruments1400. In this manner, the user control unit1100provides the surgeon S with a strong sense of directly controlling the instruments1400. To this end, position, force, strain and/or tactile feedback sensors (not shown) may be employed to transmit position, force, and tactile sensations from the instruments1400back to the surgeon's hands through the input control devices1116.

The user control unit1100is shown inFIG.4as being in the same room as the patient so that the surgeon S can directly monitor the procedure, be physically present if necessary, and speak to an assistant directly rather than over the telephone or other communication medium. In other embodiments however, the user control unit1100and the surgeon S can be in a different room, a completely different building, or other remote location from the patient allowing for remote surgical procedures.

FIG.6is a perspective view of the auxiliary equipment unit1150. The auxiliary equipment unit1150can be coupled with the endoscope (not shown) and can include one or more processors to process captured images for subsequent display, such as via the user control unit1100, or on another suitable display located locally and/or remotely. For example, where a stereoscopic endoscope is used, the auxiliary equipment unit1150can process the captured images to present the surgeon S with coordinated stereo images of the surgical site via the left eye display1112and the right eye display1114. Such coordination can include alignment between the opposing images and can include adjusting the stereo working distance of the stereoscopic endoscope. As another example, image processing can include the use of previously determined camera calibration parameters to compensate for imaging errors of the image capture device, such as optical aberrations.

FIG.7shows a front perspective view of the manipulator unit1200. The manipulator unit1200includes the components (e.g., arms, linkages, motors, sensors, and the like) to provide for the manipulation of the instruments1400and an imaging device (not shown), such as a stereoscopic endoscope, used for the capture of images of the site of the procedure. Specifically, the instruments1400and the imaging device can be manipulated by teleoperated mechanisms having a number of joints. Moreover, the instruments1400and the imaging device are positioned and manipulated through incisions or natural orifices in the patient P in a manner such that a software and/or kinematic remote center of motion is maintained at the incision or orifice. In this manner, the incision size can be minimized.

FIGS.8A and8Bare schematic illustrations of a portion of a distal end portion of a medical instrument2400, according to an embodiment. The surgical instrument2400includes a shaft2410, a hard stop structure2900, a force sensor unit2800(seeFIG.8B) including a beam2810, with one or more strain sensors (e.g., strain gauges)2830mounted on a surface along the beam2810, and an end effector2460coupled at a distal end portion of the surgical instrument2400. The end effector2460can include, for example, articulatable jaws or another suitable surgical tool that is coupled to a link2510. In some embodiments, the link2510can be included within a wrist assembly having multiple articulating links. In some embodiments the link2510is included as part of the end effector2460. As shown inFIG.8B, the shaft2410includes a distal end portion that is coupled to a proximal end portion2822of the beam2810. In some embodiments, the distal end portion of the shaft2410is coupled to the proximal end portion2822of the beam via another coupling component (such as an anchor or coupler, not shown). The shaft2410can also be coupled at a proximal end portion to a mechanical structure (not shown inFIGS.8A and8B) configured to move one or more components of the surgical instrument, such as, for example, the end effector2460. The mechanical structure can be similar to the mechanical structure7700described in more detail below with reference to medical instrument7400.

The hard stop structure2900includes a proximal end portion2933, a distal end portion2934, and a middle portion2932between the proximal end portion2933and the distal end portion2934. In some embodiments, the hard stop structure2900defines an interior lumen (not shown inFIGS.8A and8B) in which the beam2810can be at least partially disposed. In some embodiments, the hard stop structure2900is cylindrical. In some embodiments, the hard stop structure2900is at least partially open along its length or around its circumference such that an interior of the hard stop structure2900can be viewed. As shown inFIGS.8A and8B, the proximal end portion2933of the hard stop structure2900is coupled to the shaft2410and the distal end portion2934of the hard stop structure2900is coupled to the link2510. The proximal end portion2933can be fixedly coupled to the shaft2410and the distal end portion2934can be coupled to the link2510by any suitable mechanism, such as, for example, by a weld or an adhesive.

The hard stop structure2900also includes an opening2935(seeFIG.8A) defined by a wall of the hard stop structure2900. For example, the opening2935can be cut into the wall of the hard stop structure2900. In some embodiments, the opening2935can be laser cut into the wall of the hard stop structure2900. The opening2935can define one or more sets of stop surfaces (not shown inFIGS.8A and8B). In some embodiments, the stop surfaces can be formed by or a part of one or more sets of interlocking components (not shown inFIGS.8A and8B) on the wall of the hard stop structure2900. In some embodiments, the opening2935in the hard stop structure2900(and the sets of stop surfaces formed thereby) extends circumferentially around the hard stop structure2900in a spiral pattern. In some embodiments, the opening2935extends circumferentially around the wall of the hard stop structure2900more than one revolution. For example, as shown inFIG.8A, the opening2935extends circumferentially around the hard stop structure2900by two revolutions. In some embodiments, the opening2935extends circumferentially around the wall of the hard stop structure2900by more than two revolutions. The hard stop structure2900can limit the displacement and relative movement of the beam relative to a center axis of the shaft2410and/or relative to a center axis ABof the beam2810(seeFIG.8B) when a strain in the beam2810exceeds a preset amount as described in more detail below. Further, in some embodiments, the hard stop structure2900can produce a reactive moment when the strain in the beam2810exceeds a present amount as described in more detail below.

As described above, the hard stop structure2900can prevent or limit the hard stop structure2900(and the beam2810) from further bending or displacement when a desired preset bend angle or displacement is reached. Specifically, one or more sets of stop surfaces can contact each other to limit further displacement of the hard stop structure2900. In some embodiments, the hard stop structure2900can include a set of stop surfaces on at least one portion or side of the hard stop structure2900that can prevent or limit further bending or displacement of the hard stop structure2900(and beam2810). In some embodiments, the hard stop structure2900can include a set of stop surfaces on opposite sides of the hard stop structure2900(i.e., both the compression side and the tension side of the hard stop structure2900) that can prevent further bending or displacement of the hard stop structure2900and beam2820. Thus, in such an embodiment, the hard stop structure2900produces a reactive moment instead of a single reactive force once the stop surfaces engage each other. For example, when a force imparted on a distal end of the medical device2400causes the distal end of the beam2810to bend relative to a proximal end of the beam or relative to a center axis of the beam2810or shaft2410, the opposing stop surfaces of the hard stop structure2900can limit the range of motion of the beam2810. In some embodiments, the opposing stop surfaces of the hard stop structure2900can limit the range of motion of the beam in all directions of lateral force imparted on the distal end portion of the medical device.

The beam2810includes a middle portion2820(which functions as an active portion of the beam for force sensing), a proximal end portion2822and a distal end portion2824. The beam2810defines a beam center axis AB, which can be aligned within a center axis (not shown inFIGS.8A and8B) of the instrument shaft2410. As shown, the strain sensor2830is coupled to the middle portion2820of the beam2810. Thus, the middle portion2820functions as the active portion of the beam2810to sense strain on beam representative of the forces applied to the instrument2400. Although shown as including only one strain sensor2830, in other embodiments, the beam2810can include any number of strain sensors2830in various arrangements. The distal end portion2824of the beam2810is coupled to the end effector2460via a link2510. In some embodiments, the link2510can be, for example, a clevis of the end effector2460.

Generally, during a medical procedure, the end effector2460contacts anatomical tissue, which may result in X, Y, or Z direction forces being imparted on the end effector2460and that may result in moment forces such as a moment MYabout a y-direction axis as shown in FIGS.8A and8B. The one or more strain sensors2830(only one strain sensor2830is shown), which can be a strain gauge, can measure strain in the beam2810which can be used to determine the forces imparted on the end effector2460in the X and Y axes directions. These X and Y axes forces are transverse (e.g., perpendicular) to the Z axis (which is parallel or collinear with the center axis AB). Such transverse forces acting upon the end effector2460can cause a bending of the beam2810(about either or both of the X axis or the Y axis), which can result in a tensile strain imparted to one side of the beam2810and a compression strain imparted to the opposite side of the beam2810. The strain sensors2830on the beam2810can measure such tensile and compression strains.

Although shown as including only the force sensor unit2800, in some embodiments, the instrument2400(or any of the instruments described herein) can include additional force sensor units to measure the axial force(s) (i.e., in the direction of the Z-axis parallel to the beam center axis AB) imparted on the end effector2460. An axial force sensor unit in an example surgical instrument can comprise a deflectable planar diaphragm sensor that deflects in response to a force. Alternatively, a deflectable ferrite core can be used within an inductive coil may be used or a or a fiber Bragg grating formed within an optical fiber can be used, for example. Other axial force sensor units may be used to sense a resilient axial displacement of the shaft2410(e.g., relative to the proximally mounted mechanical structure, not shown). An axial force FZimparted to the end effector2460can cause axial displacement of the shaft2410in a direction along a center axis of the shaft (substantially parallel to the beam center axis AB). The axial force FZmay be in the proximal direction (e.g., a reactive force resulting from pushing against tissue with the end effector) or it may be in the distal direction (e.g., a reactive force resulting from pulling tissue grasped with the end effector).

As described above, X and Y forces imparted on the end effector2460can result in strain in the beam2810when the beam2810is displaced (e.g., bent) relative to the center axis ABof the beam2810and thus relative to a center axis of the shaft2410. Said another way, a distal end portion of the beam2810can bend relative to a proximal end portion of the beam2810such that the end portion of the beam is displaced a deflection distance relative to the center axis AB. As described above, the hard stop structure2900can limit this displacement of the beam2810when a strain in the beam2810exceeds a preset amount. Further, in some embodiments, the hard stop structure2900can produce a reactive moment when the strain in the beam2810exceeds the preset amount and the hard stop structure2900is displaced by a preset bending angle. More specifically, the hard stop2900can include a first set of opposing surfaces that contact each other when the hard stop structure2900is in tension and displaced by a threshold displacement and a second set of opposing surfaces that are in contact when the hard stop structure2900is in compression and displaced by the threshold displacement. In such a case, the hard stop structure2900produces a reactive moment.

Although the hard stop structure2900is shown as including an opening2935that extends around at least a portion of the wall of the hard stop structure2900, in other embodiments, a hard stop can include any suitable structure that includes one or more pairs of stop surface. For example,FIGS.9A and9Bare schematic illustrations of a portion of a distal end portion of a medical instrument3400, according to an embodiment. The surgical instrument3400includes a shaft3410, a hard stop structure3900, a force sensor unit3800including a beam3810, and strain sensors (e.g., strain gauges)3830mounted on a surface along the beam3810, and a link3510coupled at a distal end portion of the surgical instrument3400. The link3510can be, for example, part of or coupled to an end effector (not shown) that can include, for example, articulatable jaws or another suitable surgical tool. In some embodiments, the link3510can be included within a wrist assembly having multiple articulating links. A proximal portion of the beam3810is coupled to the shaft3410and a distal portion of the beam3810is coupled to the link3510. In some embodiments, the distal end portion of the shaft3410is coupled to the proximal portion of the beam3810via another coupling component (such as an anchor or coupler, not shown). The shaft3410can also be coupled at a proximal end portion to a mechanical structure (not shown inFIGS.9A and9B) configured to move one or more components of the surgical instrument. The mechanical structure can be similar to the mechanical structure7700described in more detail below with reference to medical instrument7400.

The hard stop structure3900includes a proximal end portion3933, a distal end portion3934, and a middle portion3932between the proximal end portion3933and the distal end portion3934. As shown inFIGS.9A and9B, the proximal end portion3933of the hard stop structure3900is coupled to the shaft3410and the distal end portion3934of the hard stop structure3900is coupled to the link3510. The proximal end portion3933can be fixedly coupled to the shaft3410and the distal end portion3934can be coupled to the link3510by any suitable mechanism, such as, for example, by a weld or an adhesive. In this manner, displacement of the link3510relative to the shaft3410will cause displacement of the distal end portion3934of the hard stop structure3900relative to the proximal end portion3933of the hard stop structure3900. The hard stop structure3900also includes a set of stop surfaces that limit a range of motion of the distal end of the beam3810(and the distal end portion3934of the hard stop structure3900) with respect to the proximal end of the beam3810(and the proximal end portion3933of the hard stop structure3900). Specifically, the hard stop structure3900includes an opening3935defined by a wall of the hard stop structure3900. As shown in this embodiment, the opening3935defines a set of interlocking components3920including the components3940,3950and3960on the wall of the hard stop structure3900. In some embodiments, the opening3935in the hard stop structure3900and interlocking components3940,3950,3960can extend at least partially circumferentially around the hard stop structure3900. For example, the opening3935can be cut into the wall of the hard stop structure3900. In other embodiments, the opening3935in the wall and the interlocking components3940,3950,3960can be primarily on a single side of the hard stop structure3900.

As described above for previous embodiments, the hard stop structure3900can limit the displacement of the beam3810relative to a center axis C-A of the shaft3410and/or relative to a center axis ABof the beam3810when a strain in the beam3810exceeds a preset amount. Said another way, the hard stop structure3900can limit the displacement or bending of the beam3810when the beam3810is displaced or bends a preset amount. More specifically, when a force F (shown inFIG.9B) is imparted on a distal portion of the medical device (e.g., at link3510) in the X or Y directions (seeFIGS.8A and8Bfor reference to X, Y and Z directions), such transverse force can cause the beam3810to bend (about either or both of the X axis or the Y axis), which can result in a tensile strain imparted to one side of the beam3810and a compression strain imparted to the opposite side of the beam3810. The strain sensors3830on the beam3810can measure such tensile and compression strains. As the beam3810bends to a preset bending angle, a surface of the component3950will contact a surface of the component3940and limit further movement of the beam3810as shown inFIG.9B. The opposing surfaces of the components3950and3940thus function as a set of stop surfaces to prevent the hard stop structure3900and the beam3810, which is coupled to the same components of the medical device (i.e., the link and the shaft) from further displacement or bending.

FIGS.9A and9Billustrate an embodiment with interlocking components (including stop surfaces) on only one side of the hard stop structure3900. In other embodiments, as shown for example inFIGS.10A and10B, a hard stop structure includes at least two sets of interlocking components3920(which function as stop surfaces) on opposite sides of the hard stop structure. In this manner, the hard stop structure3900can produce multiple points of contact when the strain in the beam exceeds a preset amount.FIGS.10A and10Bare schematic illustrations of a portion of a distal end portion of a medical instrument4400, according to an embodiment. The surgical instrument4400includes a shaft4410, a hard stop structure4900, a force sensor unit4800including a beam4810, and strain sensors (e.g., strain gauges)4830mounted on a surface along the beam4810, and a link4510coupled at a distal end portion of the surgical instrument4400. The link4510can be, for example, part of or coupled to an end effector (not shown) that can include, for example, articulatable jaws or another suitable surgical tool. In some embodiments, the link4510can be included within a wrist assembly having multiple articulating links. A proximal portion of the beam4810is coupled to the shaft4410and a distal portion of the beam4810is coupled to the link4510. In some embodiments, the distal end portion of the shaft4410is coupled to the proximal portion of the beam4810via another coupling component (such as an anchor or coupler, not shown). The shaft4410can also be coupled at a proximal end portion to a mechanical structure (not shown inFIGS.10A and10B) configured to move one or more components of the surgical instrument. The mechanical structure can be similar to the mechanical structure7700described in more detail below with reference to medical instrument7400.

The hard stop structure4900includes a proximal end portion4933, a distal end portion4934, and a middle portion4932between the proximal end portion4933and the distal end portion4934. The hard stop structure4900includes a wall that defines an interior region4931within which the beam4800can be at least partially disposed. In this manner, the wall4921has a first side4922(shown as the side above the beam4810) and a second, opposite side4923(shown as the side below the beam4810). In some embodiments, the hard stop structure4900can only partially surround the beam4810. In other embodiments, the hard stop structure4900can be cylindrical. As shown inFIGS.10A and10B, the hard stop structure4900is at least partially open along its length and around at least a portion of its circumference such that the interior lumen4931of the hard stop structure4900can be viewed. As shown inFIGS.10A and10B, the proximal end portion4933of the hard stop structure4900is coupled to the shaft4410and the distal end portion4934of the hard stop structure4900is coupled to the link4510. The proximal end portion4933can be fixedly coupled to the shaft4410and the distal end portion4934can be coupled to the link4510by any suitable mechanism, such as, for example, by a weld or an adhesive. In this manner, displacement of the link4510relative to the shaft4410will cause displacement of the distal end portion4934of the hard stop structure4900relative to the proximal end portion4933of the hard stop structure4900.

The hard stop structure4900also includes a first opening4935and a second opening4935′ defined by the wall4921of the hard stop structure4900. In this embodiment, the opening4935defines interlocking components4940,4950and4960on the wall4921of the hard stop structure4900on the first side4922of the hard stop structure4900and the opening4935′ defines interlocking components4940′,4950′ and4960′ on the second, opposite side4923of the hard stop structure4900. The openings4935and4935′ in the hard stop structure4900can each extend at least partially circumferentially around the hard stop structure4900such that additional interlocking components can be defined at different locations along the hard stop structure4900.

As described above for previous embodiments, the hard stop structure4900can limit the displacement of the beam4810relative to a center axis C-A of the shaft4410and/or relative to a center axis ABof the beam4810when a strain in the beam4810exceeds a preset amount or when the beam4810bends or is displaced a preset amount (e.g., preset bending angle). More specifically, when a force F (shown inFIG.10B) is imparted on a distal portion of the medical device (e.g., at link4510) in the X or Y directions (seeFIGS.8A and8Bfor reference to X, Y and Z directions), such transverse force can cause the beam4810to bend (about either or both of the X axis or the Y axis), which can result in a tensile strain imparted to one side of the beam4810and a compression strain imparted to the opposite side of the beam4810. The strain sensors4830on the beam4810can measure such tensile and compression strains. As the beam4810bends to a preset bending angle, a surface of the component4950will contact a surface of the component4960and a surface of the component4950′ will contact a surface of the component4940′ on the opposite side of the hard stop structure4900. In this example, the surfaces of the components4950and4960and the surfaces of the components4950′ and4940′ function as stop surfaces to prevent the hard stop structure4900and the beam4810, which is coupled to the same components of the medical device as the hard stop structure4900(i.e., the link and the shaft) from further displacement or bending. Thus, in this embodiment, the hard stop structure4900includes two pairs of stop surfaces that can prevent further bending or displacing of the beam4810. Specifically, one pair of stop surfaces contacts each other on the side of the hard stop structure4900that is under compression and another pair of stop surfaces contacts each other on side of the hard stop structure4900that is under tension. Thus, in such an embodiment, the hard stop structure4900produces a reactive moment instead of a single reactive force when the hard stop surfaces engage each other.

To further illustrate how the multiple points of contact reduce the likelihood of force distortion of the force sensor unit4800,FIGS.11A and11Bshow free-body diagrams of the medical instrument4400ofFIGS.10A and10B. Specifically,FIG.11Ais a free-body diagram showing the distance L, which is the distance from the base (point GND1) of the beam4810to the point where the hard stop structure4900will ultimately contact the beam (point GND2). The distance d represents the distance between the point where the hard stop structure4900will ultimately contact the beam4810(point GND2) and where the force F is applied to the distal tip component. InFIG.11Athe beam4810and the hard stop structure4900are in a condition where, like shown inFIG.10A, the hard stop structure does not limit the displacement of the beam. Thus, the beam is free to deflect by a bending angle Φ (FIG.11A) until the beam reaches a preset bending angle (referred to as (Φmax). When the bending angle is less than Φmax, the influence of the hard stop structure on the bending of the beam is negligible. The bending of the beam at the point GND2can be modeled as set forth in Eqs. (3) and (4):

-Φ=F⁢L22⁢EI-M⁢LEIEq.⁢(3)M=FdEq.⁢(4)

Where E is the modulus of elasticity of the beam and I is the moment of inertia of the XY cross-section of the beam. Substituting Eq. (4) into Eq. (3) yields the following equation for the bending angle, which can be rearranged for the force F applied to the distal tip component:

Φ=F⁢L22⁢EI+FdLEIEq.⁢(5)F=Φ⁢⁢EIL⁡(L+2⁢d)Eq.⁢(6)

Accordingly, when the bending angle has reached the preset maximum bending angle, Eq. (6) can be expressed as:

FMAX⁢=Φmax⁢EIL⁡(L+2⁢d)Eq.⁢(7)

FIG.11Bshows the condition where F has exceeded FMAXand the beam4810and the hard stop structure4900are in a condition where, like shown inFIG.10B, the surfaces of the components4950and4960and the surfaces of the components4950′ and4940′ function as stop surfaces to prevent the hard stop structure4900and the beam4810from further bending. In this condition, the hard stop structure functions as a parallel cantilevered support member with the beam. AlthoughFIG.11Bis a free-body diagram to model the behavior at forces greater than FMAX, the beam and the hard stop are shown as being straight for purposes of clarity. At this condition, the force, the bending angle, and the deflection at point GND2can be represented as:
F=FMAX+ΔFEq. (8)
Φ=Φmax+ΔΦ  Eq. (9)
δ=δmax+Δδ  Eq. (10)

Because the Eq. (3) through Eq. (7) apply for conditions where the force F is less than or equal to FMAX,FIG.11Cis simplified to model the ΔF only, with the beam “cut” at point GND2.FIG.11Cshows the reactive force FRproduced by the contact of pairs of stop surfaces of the hard stop structure4900. Importantly, because the hard stop structure has two points of contact (on opposite sides of the beam), the hard stop structure also produces a reactive moment MRat point GND2.FIG.11Calso shows the effective force FEand the effective moment MEproduced by the cantilever coupling to the shaft. Modeling the beam at the point of contact (at GND2) using the force and moment equations provides:
FE+FR−ΔF=0   Eq. (11)
ME+MR−ΔFd=0   Eq. (12)

Because the hard stop structure is rigidly connected to the beam when the pairs of surfaces contact each other, the deflection δ and bend angle Φ of the beam at point GND2(length L) is modeled as being the same as that of the hard stop structure. Accordingly, the deflection δ and bend angle Φ are given by:

Δ⁢Φ=FE⁢L22⁢EI+ME⁢LEI=FR⁢L22⁢EH⁢IH+MR⁢LEH⁢IHEq.⁢(13)Δ⁢⁢δ=FE⁢L33⁢EI+ME⁢L22⁢EI=FR⁢L33⁢EH⁢IH+MR⁢L22⁢EH⁢IHEq.⁢(14)

Solving Eq. (11) through Eq. (14) for FEyields:

FE=(EIEI+EH⁢IH)⁢Δ⁢FEq.⁢(15)

Where EHis the modulus of elasticity of the hard stop structure and IHis the moment of inertia of the XY cross-section of the hard stop structure. The total force of the beam (that will be measured by the strain sensors is given by Eq. (6) when the applied force F is less than FMAX. When the applied force F is greater than FMAX, however, the total force of the beam is given by:
Fbeam=FMAX+FEEq. (16)

Where FEis determined by Eq. (15). If the hard stop structure is considered as having an infinite stiffness, then FE=0. In such situations, after FMAXis reached, the force measured by the strain sensors will remain at FMAXas the actual force applied continues to increase. This condition is shown inFIG.12A, which is a graph showing measured force (based on the strain signals) as a function of the actual force applied. As shown, when the hard stop structure does not limit the displacement of the beam (i.e., the stop surfaces are not in contact with each other), the beam is free to deflect and the relationship between the measured force and the actual force is linear, which allows for an accurate calibration (i.e., based on the slope of the line). At conditions where the two sets of stop surfaces are in contact (i.e., at the condition where the applied force F is equal to or greater than the FMAX), the measured force remains substantially constant (at a value of FMAX) as the applied force increases. In this manner, the hard stop structure4900prevents the measured force from decreasing, thereby minimizing the problem of force distortion (or inversion).

If the hard stop structure is considered as having a finite stiffness, then FEwill be nonzero, but will have a high value. In such situations, after FMAXis reached, the force measured by the strain sensors will increase as the actual force applied continues to increase. This condition is shown inFIG.12B, which is a graph showing measured force (based on the strain signals) as a function of the actual force applied. As shown, when the hard stop structure does not limit the displacement of the beam (i.e., the stop surfaces are not in contact with each other), the beam is free to deflect and the relationship between the measured force and the actual force is linear, which allows for an accurate calibration (i.e., based on the slope of the line). At conditions where the two sets of stop surfaces are in contact (i.e., at the condition where the applied force F is equal to or greater than the FMAX), the measured force continues to increase as the applied force increases, but does so at a much lower slope.

As shown in bothFIGS.12A and12B, the magnitude of the distance d impacts the FMAX(the force at which the two sets of stop surfaces are in contact). Specifically, for a given geometry and design, the further away from the contact point (GND2) the force F is applied the sooner the two sets of stop surfaces will contact. Said another way, as the distance d increases, the FMAXdecreases. Thus, the hard stop structure4900(and any of the hard stop structures described herein) can be optimized for a desired maximum force FMAXby changing the position of the contact surfaces.

FIGS.13A-20Care various views of a medical instrument7400, according to an embodiment. In some embodiments, the instrument7400or any of the components therein are optionally parts of a surgical system that performs surgical procedures, and which can include a manipulator unit, a series of kinematic linkages, a series of cannulas, or the like. The instrument7400(and any of the instruments described herein) can be used in any suitable surgical system, such as the MIRS system1000shown and described above. The instrument7400includes a mechanical structure7700, a shaft7410, a hard stop structure7900, a force sensor unit7800that includes a beam7810, a wrist assembly7500, and an end effector7460. Although not shown, the instrument7400can also include a number of cables that couple the mechanical structure7700to the wrist assembly7500and end effector7460. The instrument7400is configured such that select movements of the cables produces rotation of the wrist assembly7500(i.e., pitch rotation) about a first axis of rotation A1(seeFIG.13B) (which functions as a pitch axis, the term pitch is arbitrary), yaw rotation of the end effector7460about a second axis of rotation A2(seeFIG.13B) (which functions as the yaw axis, the term yaw is arbitrary), a cutting rotation of the tool members of the end effector7460about the second axis of rotation A2, or any combination of these movements. Changing the pitch or yaw of the instrument7400can be performed by manipulating the cables in a similar manner as described, for example, in U.S. Pat. No. 8,821,480 B2 (filed Jul. 16, 2008), entitled “Four-Cable Wrist with Solid Surface Cable Channels,”, which is incorporated herein by reference in its entirety. Thus, the specific movement of each of the cables to accomplish the desired motion is not described below.

The shaft7410includes a proximal end (not shown) that is coupled to the mechanical structure7700, and a distal end7412(seeFIGS.13C and14B) that is coupled to the beam7810via an anchor7925. In some embodiments, the proximal end of the shaft7410is coupled to the mechanical structure7700in a manner that allows movement of the shaft7410along a center axis C-A of the shaft7410(shown inFIG.13C) relative to the mechanical structure7700. Allowing the shaft7410to “float” in the Z direction facilitates measurement of forces along the Z axis, as described herein. In some embodiments, the proximal end of the shaft7410can be movably coupled to the mechanical structure7700via a four bar linkage of the types shown and described in International Patent Appl. No. PCT/US2019/061883 (filed Nov. 15, 2019), entitled “Surgical Instrument with Sensor Aligned Cable Guide,” which is incorporated herein by reference in its entirety. The shaft7410also defines a lumen (not shown) and/or multiple passageways through which the cables and other components (e.g., electrical wires, ground wires, or the like) can be routed from the mechanical structure7700to the wrist assembly7500. The anchor7925can be received at least partially within the lumen of the shaft7410and can be fixedly coupled to the shaft7410via an adhesive bond, a weld, or any other permanent coupling mechanism (i.e., a coupling mechanism that is not intended to be removed during normal use).

The mechanical structure7700produces movement of the cables (not shown) to produce the desired movement (pitch, yaw, or grip) at the wrist assembly7500. Specifically, the mechanical structure7700includes components and controls to move some of the cables in a proximal direction (i.e., to pull in certain cables) while simultaneously allowing the distal movement (i.e., releasing or “paying out”) of other of the cables in equal lengths. In this manner, the mechanical structure7700can maintain the desired tension within the cables, and in some embodiments, can ensure that the lengths of the cables are conserved (i.e., moved in equal amounts) during the entire range of motion of the wrist assembly7500. In other embodiments, however, conservation of the lengths of the cables is not required.

In some embodiments, the mechanical structure7700can include one or more mechanisms that produce translation (linear motion) of a portion of the cables. Such a mechanisms can include, for example, a gimbal, a lever, or any other suitable mechanism to directly pull (or release) an end portion of any of the cables. For example, in some embodiments, the mechanical structure7700can include any of the mechanical structures (referred to as backend assemblies or actuators) or components described in U.S. Patent Application Pub. No. US 20157/0047454 A1 (filed Aug. 15, 2014), entitled “Lever Actuated Gimbal Plate,” or U.S. Pat. No. 6,817,974 B2 (filed Jun. 28, 2001), entitled “Surgical Tool Having Positively Positionable Tendon-Actuated Multi-Disk Wrist Joint,” each of which is incorporated herein by reference in its entirety. In other embodiments, however, the mechanical structure7700can include a capstan or other motor-driven roller that rotates or “winds” a portion of any of the bands to produce the desired band movement. For example, in some embodiments, the mechanical structure7700can include any of the mechanical structures (referred to as backend assemblies or actuators) or components described in U.S. Pat. No. 9,204,923 B2 (filed Jul. 16, 2008), entitled “Medical Instrument Electronically Energized Using Drive Cables,” which is incorporated herein by reference in its entirety.

Referring toFIG.13B, the wrist assembly7500includes a proximal first link7510and a distal second link7610. The first link7510includes a distal portion that is coupled to a proximal portion of the second ink7610at a joint such that the second link7610can rotate relative to the first link7510about a first axis of rotation A1(which functions as the pitch axis, the term pitch is arbitrary). The proximal first link7510includes a proximal portion that is coupled to the beam7810as described in more detail below.

A distal end of the distal second link7610is coupled to the end effector7460such that the end effector7460can rotate about a second axis of rotation A2(seeFIG.13B) (which functions as the yaw axis). The end effector7460can include at least one tool member7462having a contact portion7464configured to engage or manipulate a target tissue during a surgical procedure. For example, in some embodiments, the contact portion7464can include an engagement surface that functions as a gripper, cutter, tissue manipulator, or the like. In other embodiments, the contact portion7464can be an energized tool member that is used for cauterization or electrosurgical procedures. The end effector7460is operatively coupled to the mechanical structure7700such that the tool member7462rotates relative to shaft7410about the first axis of rotation A1. In this manner, the contact portion7464of the tool member7462can be actuated to engage or manipulate a target tissue during a surgical procedure. The tool member7462(or any of the tool members described herein) can be any suitable medical tool member. Moreover, although only one tool member7462is identified, as shown, the instrument7400can include two tool members that cooperatively perform gripping or shearing functions. In other embodiments, an end effector can include more than two tool members.

The beam7810includes a proximal end portion7822, a middle portion (which functions as an active portion of the beam7810) and a distal end portion7824. The beam7810has a center axis ABdefined along a length of the beam7810(seeFIG.15). One or more strain sensors7830(seeFIG.18) are mounted on the middle portion7820of the beam7810. The strain sensors7830are not shown in some of the figures for illustrative purposes only. The strain sensors7830can be, for example, strain gauges, and can be used to measure forces imparted on the surgical instrument during a surgical procedure as described in more detail below. In this embodiment, the middle portion7820defines four side surfaces disposed perpendicular to each other and on which the strain sensors7830can be mounted (seeFIG.18). In this embodiment, the cross-section of the middle portion7820is substantially square shaped. Thus, the cross-sectional shape of the middle portion7820is identical for every ninety degrees of rotation. In this manner, the output from the strain sensors7830(which are shown disposed on only two of the four sides of the middle portion7820) will be consistent throughout the entire range of the roll of the shaft7410(i.e., rotation of the shaft7410about the center axis AB). In some alternative embodiments, the strain sensors7830can be disposed on only a single side of the beam7810.

Both the distal end portion7824and the proximal end portion7822of the beam7810are tapered but each has a different cross-sectional shape and size than the other. In this embodiment, the proximal end portion7822defines an end cutout region7821(seeFIGS.17and13) that is used for manufacturing purposes and also provides clearance for routing of electrical components (not shown) disposed within the shaft7410and anchor7925. The proximal end portion7822also defines a side cutout region7823(seeFIG.16) that provides an entry into the lumen of the shaft7410(via the cutout7927in the anchor) to allow routing of the electrical wiring to the strain sensors7830.

The beam7810is coupled to a distal end portion7412of the shaft7410via the anchor7925and to the proximal link7510of the wrist assembly7500(see, e.g.,FIGS.13C-15). More specifically, the anchor7925defines an opening7926(seeFIG.16) that can matingly receive the tapered proximal end portion7822of the beam7810. The anchor7925also defines the cutout7927through which wires can be routed. The proximal end portion7822can be coupled to the anchor7925with, for example, welding, an adhesive or other suitable coupling methods. Similarly, the proximal link7510defines an opening7515(seeFIG.17) that can matingly receive the distal end portion7824of the beam7810. The distal end portion7824can be coupled to the link7510with, for example, welding, an adhesive or other suitable coupling methods.

The hard stop structure7900includes a proximal end portion7933, a distal end portion7934, and a middle portion7932between the proximal end portion7933and the distal end portion7934. The hard stop structure7900defines an interior lumen (not shown) within which the beam7810is disposed. In this embodiment, the hard stop structure7900is cylindrical. As shown inFIG.13B, the proximal end portion7933of the hard stop structure7900is coupled to the shaft7410and the distal end portion7934of the hard stop structure7900is coupled to the proximal link7510. The proximal end portion7933can be fixedly coupled to the distal end portion7412of the shaft7410and the distal end portion4934can be coupled to the proximal link7510by any suitable mechanism, such as, for example, by a weld or an adhesive. As shown inFIGS.19A and19B, the proximal end portion7933an include a tapered portion and an elongate slot to facilitate fixation to the shaft7410. In this manner, displacement of the proximal link7510relative to the shaft7410will cause displacement of the distal end portion7934of the hard stop structure7900relative to the proximal end portion7933of the hard stop structure7900.

The hard stop structure7900also includes an opening7935defined by a wall7921of the hard stop structure7900. The opening7935can be cut into the wall7921of the hard stop structure7900by any suitable methods, such as, for example, laser cut, electronic discharge machining, or the like. In some embodiments, the hard stop structure can be a laser-cut tube. In this embodiment, the opening7935defines multiple interlocking components that wrap about a circumference of the hard stop structure in a spiral pattern. More specifically, the opening7935has a first end point7936(see, for example,FIG.19B), wraps around the circumference of the hard stop structure7900, and has a second end point7937(see, for example,FIG.19A) on an opposite side of the hard stop structure7900. The multiple interlocking components7920form a repeating pattern within the wall7921of the hard stop structure7900about the circumference of the hard stop structure7900. In this manner, the hard stop structure7900can limit the range of motion (i.e., bending) of the hard stop structure7900and the beam7810in all directions lateral to the Z axis, and not just only in the X direction or Y direction.

Each of the interlocking components7920includes multiple surfaces. As shown inFIGS.20A-20C, the interlocking components include components7930(only partially shown in the enlarged view ofFIGS.20A-20C),7940,7950,7960and7970(only partially shown in the enlarged view ofFIGS.20A-20C). Each of the components include multiple surfaces that contact corresponding surfaces of adjacent components in certain instances when a motion limit has been reached. For example, as shown inFIG.20A, the component7940includes surfaces7941,7942,7943,7944,7945,7946,7947, and7948. The component7950includes surfaces7951,7952,7953,7954,7955,7956,7957,7958and the component7960includes surfaces7961,7962,7963,7964,7965,7966,7967and7968. Components7930and7970have similar surfaces but are not labeled inFIGS.20A-20C. More details regarding the function of the hard stop structure7900are described below.

In use, the end effector7460contacts anatomical tissue, which may result in X, Y, or Z direction forces (seeFIG.13B) being imparted on the end effector7460and that may also result in moment forces about the various axes. The strain sensors7830(seeFIG.18) can be used to measure strain in the beam as a result of such forces imparted on the end effector7460. More specifically, the strain sensors7830can measure forces imparted on the end effector7460that are transverse (e.g., perpendicular) to the center axis ABof the beam7810as such forces are transferred to the beam7810in the X and Y directions (seeFIG.13C). Specifically, the transverse forces acting upon the end effector7460can cause a slight bending of the beam7810, which can result in a tensile strain imparted to one side of the beam7810and a compression strain imparted to the opposite side of the beam7810. The strain sensors7830are coupled to the beam7810to measure such tensile and compression forces.

As described above for previous embodiments, the hard stop structure7900can limit the displacement of the beam7810relative to a center axis C-A of the shaft7410and/or relative to the center axis ABof the beam7810when a strain in the beam7810exceeds a preset amount or when the beam7810bends or is displaced a preset amount (e.g., preset bending angle). More specifically, when a force F (seeFIG.13B) is imparted on a distal portion of the medical device7400(e.g., at end effector7460) in the X or Y directions (seeFIG.13Cfor reference to X, Y and Z directions), such transverse force can cause bending the beam7810to bend (about either or some combination of the X axis or the Y axis), which can result in a tensile strain imparted to one side of the beam7810and a compression strain imparted to the opposite side of the beam7810. The strain sensors7830on the beam7810can measure such tensile and compression strains. For example, in this example embodiment, with the force F shown inFIG.13B, the hard stop structure7900and beam7810would bend downward in the direction of arrow B such that a tensile strain would be imparted on a top side TS of the beam7810and a compression strain would be imparted on a bottom side BS of the beam7810.

As the beam7810bends, specific surfaces of the interlocking components7920are configured to engage each other when the beam7810bends to a desired preset bending angle or is otherwise displaced to a preset amount. Thus, the surfaces of the interlocking components7920function as stop surfaces to prevent the hard stop structure7900and beam7810from bending (or being displaced any further). More specifically,FIG.20Bis an enlarged view of a portion of the hard stop structure7900illustrating the function of the hard stop structure7900when compression strain is imparted on a portion of the hard stop structure7900andFIG.20Cis an enlarged view of the portion of the hard stop structure illustrating the function of the hard stop structure7900when a tensile strain is imparted on the portion of the hard stop structure7900. As shown inFIG.20B, when under compression, the surface7941of component7940contacts the surface7953of component7950, the surface7954of component7950contacts the surface7968of components7960, the surface7951contacts the surface7943of component7940, and the surface7958of component7950contacts the surface7964of component7960. The same corresponding surfaces of the other adjacent components (e.g.,7930and7970) can contact each other in the same manner. For example, the surface7944of component7940can contact a corresponding surface of component7930as shown inFIG.20B. Thus, for the example when the bottom side BS of the beam7810(and the hard stop structure7900) is in compression, these stop surfaces (which function as the compression stop surfaces) contact each other to limit further displacement. As shown inFIG.20C, when under tension, the surface7952of component7950contacts the surface7942of component7940and surface7956of component7950contacts surface7966of component7960. The same corresponding surfaces of the other adjacent components (e.g.,7930and7970) can contact each other in the same manner. For example, surface7946of component7940can contact a corresponding surface of component7930as shown inFIG.20C. Thus, for the example given when the top side TS of the beam7810(and the hard stop structure7900) is in tension, these stop surfaces (which function as the tension stop surfaces) contact each other to limit further displacement. Additionally, when the bottom side BS of the beam7810is under compression, the tension stop surfaces on the bottom side are spaced apart from each other, and when the top side TS of the beam7810is under tension, the compression stop surfaces on the top side are spaced apart from each other.

When the surfaces of the components7920contact each other, further displacement of the hard stop structure7900(and beam7810) is prevented. Thus, the contacting surfaces of the components7920function as stop surfaces to prevent the hard stop structure7900and the beam7810from further displacement or bending. In this embodiment, the interlocking components7920extend about the circumference of the hard stop structure7900and therefore provide stop surfaces at various locations about the circumference of the hard stop structure7900. With this configuration, the interlocking components7920can limit the displacement of the hard stop structure7900(and beam7810) in all directions of lateral forces imparted on the hard stop structure7900(i.e., lateral forces in the X-direction, the Y-direction, or having any component in the X- or Y-direction). Thus, when a force F (as shown inFIG.13B) is imparted on the distal end of the medical device7400, causing the hard stop structure7900and beam7810to bend, interlocking components on both the top side TS and bottom side BS of the hard stop structure7900can engage (i.e., the opposing surfaces of the interlocking components contact each other) to prevent further bending or displacing on both the compression side and the tension side of the hard stop structure7900(and beam7810). Thus, in this embodiment, the hard stop structure7900provides a reactive moment instead of a single reactive force once the hard stop surfaces engage.

Although the above description of the function of the hard stop structure7900describes only components7930,7940,7950,7960and7970, it should be understood that the hard stop structure7900includes multiple interlocking components7920, as shown, for example, inFIGS.19A and19B. Thus, as the beam7810and hard stop7900bend, various stop surfaces of the components7920will contact each other around the circumference of the hard stop structure7900depending on the direction of the force imparted on the medical device. Additionally, although each component (e.g., component7940) is shown as including two compression stop surfaces (e.g., surfaces7941,7948) and two tension stop surfaces (e.g., surfaces7942,7946), in other embodiments each component can have any number of stop surfaces that engage with corresponding stop surfaces to limit bending.

In this embodiment, the opening7935defines multiple interlocking components that wrap about a circumference of the hard stop structure in a spiral pattern. The spiral pattern is accommodated by the asymmetry of the shape of the interlocking components7920. Specifically, the surfaces7947and7949are not stop surfaces, but are instead substantially parallel to the Z-axis and do not contact their adjacent surfaces during either compression or tension. Moreover, the surface7947is longer than the surface7949, which causes the component7940to be asymmetrical. This causes the interlocking components7920to wrap about a circumference of the hard stop structure in a spiral pattern. The difference in length between the surfaces7947and7949determines the angle of the pattern (relative to the center axis C-A of the shaft7410and/or the center axis ABof the beam7810). For example, although the spiral angle Θ of the opening7935is between about 85 and 90 degrees (seeFIG.19A), in other embodiments, increasing the difference in length between the surface7947and the surface7949can result in smaller spiral angles (e.g., between 75 and 85 degrees; between 60 and 75 degrees). In an alternative embodiment, a hard stop structure can include multiple individual openings (e.g., “rings”) that each wrap about a circumference of the hard stop structure instead of a continuous spiral pattern.

In addition to producing contacting stop surfaces on both the top side TS of the hard stop structure7900and the bottom side BS of the hard stop structure7900, the multiple revolutions of the interlocking components7920also produces additional points of contact at different locations along the center axis ABof the beam7810. The multiple revolutions also allows for a greater amount of deflection of the hard stop structure7900. For example, each set of interlocking components7920allows an amount of bend of the beam7810equal to the size (e.g., width) of the opening7935. Thus, a greater number of revolutions of the opening7935around the hard stop structure7900, allows for a greater amount of bending of the beam7810.

Although the hard stop structure7900is shown as defining an opening7935that extends about the circumference of the hard stop structure7900by about eight revolutions, in other embodiments, a hard stop structure can define an opening (or can include a set of interlocking components) that extends any number of revolutions about the circumference. For example, a hard stop structure can define an opening that extends about the circumference of the hard stop 2, 3, 4, 5, 6, etc. revolutions. For example,FIG.21is a side view of a portion of a medical instrument8400, according to another embodiment. In some embodiments, the instrument8400or any of the components therein are optionally parts of a surgical system that performs surgical procedures, and which can include a manipulator unit, a series of kinematic linkages, a series of cannulas, or the like. The instrument8400(and any of the instruments described herein) can be used in any suitable surgical system, such as the MIRS system1000shown and described above.

The instrument8400can include a mechanical structure (not shown), a shaft8410, a hard stop structure8900, a force sensor unit (not shown) including a beam and one or more strain sensors disposed on the beam, a wrist assembly8500, and an end effector8460. The shaft8410, force sensor unit, wrist assembly8500and end effector8460can be constructed the same as or similar to and function the same as or similar to the like components in other embodiments described herein and are therefore not described in detail with respect this embodiment. Although not shown, the instrument8400can also include a number of cables that couple the mechanical structure to the wrist assembly8500and end effector8460. The instrument8400is configured such that select movements of the cables produces rotation of the wrist assembly8500(i.e., pitch rotation) about a first axis of rotation A1(which functions as a pitch axis, the term pitch is arbitrary), yaw rotation of the end effector8460about a second axis of rotation A2(which functions as the yaw axis, the term yaw is arbitrary), a cutting rotation of the tool members of the end effector8460about the second axis of rotation A2, or any combination of these movements. Changing the pitch or yaw of the instrument8400can be performed by manipulating the cables in a similar manner as described above for medical instrument7400.

The various components of the medical device8400can be configured the same as or similar to, and function the same as or similar to, similar components described above for previous embodiments and therefore are not described in detail with reference to this embodiment. For example, in this embodiment, the hard stop structure8900is tubular or cylindrical, and includes an opening8935in a wall8921of the hard stop structure8900. The opening8935can be formed into the hard stop structure8900by any suitable methods, such as, for example, laser cut, electronic discharge machining, or the like. In some embodiments, the hard stop structure can be a laser-cut tube. The opening8935defines multiple interlocking components8920having opposing stop surfaces. In this embodiment, the opening8935extends about the circumference of the hard stop structure8900two revolutions in a spiral pattern. The hard stop structure8900includes a proximal end portion8933, a distal end portion8934, and a middle portion8932between the proximal end portion8933and the distal end portion8934. The hard stop structure8900defines an interior lumen (not shown) within which the beam is disposed.

As shown inFIG.21, the proximal end portion8933of the hard stop structure8900is coupled to the shaft8410and the distal end portion8934of the hard stop structure8900is coupled to the wrist assembly8500. The proximal end portion8933can be fixedly coupled to a distal end portion8412of the shaft8410and the distal end portion8934can be coupled to the wrist assembly8500by any suitable mechanism, such as, for example, by a weld or an adhesive. In this manner, displacement of the wrist assembly8500relative to the shaft8410will cause displacement of the distal end portion8934of the hard stop structure8900relative to the proximal end portion8933of the hard stop structure8900.

The multiple interlocking components8920formed by the opening8935define a repeating pattern within the wall8921of the hard stop structure8900about the circumference of the hard stop structure8900. In this manner, the hard stop structure7900can limit the range of motion (i.e., bending) of the hard stop structure8900and the beam8810in all directions lateral to the Z axis, and not just only in the X direction or Y direction. Each of the interlocking components8920includes multiple surfaces that contact corresponding surfaces of adjacent interlocking components in certain instances when a motion limit has been reached as described above for the previous embodiment.

In use, the end effector8460contacts anatomical tissue, which may result in X, Y, or Z direction forces (see e.g.,FIG.13Bdescribed above for medical device7400) being imparted on the end effector8460and that may also result in moment forces about the various axes. The strain sensors (not shown) can be used to measure strain in the beam (not shown) as a result of such forces imparted on the end effector8460. More specifically, the strain sensors7830can measure forces imparted on the end effector8460that are transverse (e.g., perpendicular) to the center axis ABof the beam as such forces are transferred to the beam in the X and Y directions. Specifically, the transverse forces acting upon the end effector8460can cause a slight bending of the beam, which can result in a tensile strain imparted to one side of the beam and a compression strain imparted to the opposite side of the beam. As with the previous embodiments, the strain sensors are coupled to the beam to measure such tensile and compression forces.

As described above for previous embodiments, the hard stop structure8900can limit the displacement of the beam8810relative to a center axis (not shown inFIG.21) of the shaft8410and/or relative to a center axis (not shown inFIG.21) of the beam when a strain in the beam exceeds a preset amount or when the beam bends or is displaced a preset amount (e.g., preset bending angle). More specifically, when a force F is imparted on a distal portion of the medical device8400(e.g., at end effector8460) in the X or Y directions (seeFIG.13Cfor reference to X, Y and Z directions), such transverse force can cause bending the beam to bend (about either or some combination of the X axis or the Y axis), which can result in a tensile strain imparted to one side of the beam and a compression strain imparted to the opposite side of the beam. The strain sensors on the beam can measure such tensile and compression strains. For example, in this example embodiment, with the force F, the hard stop structure8900and beam would bend downward such that a tensile strain would be imparted on a top side TS of the beam and a compression strain would be imparted on a bottom side BS of the beam.

As described above for previous embodiments, as the beam bends, specific surfaces of the interlocking components8920are configured to engage each other when the beam bends to a desired preset bending angle or is otherwise displaced to a preset amount. Thus, the surfaces of the interlocking components8920function as stop surfaces to prevent the hard stop structure8900and beam from bending (or being displaced any further). When the surfaces of the components8920contact each other, further displacement of the hard stop structure8900(and beam) is prevented. Thus, the contacting surfaces of the components8920function as stop surfaces to prevent the hard stop structure8900and the beam from further displacement or bending. In this embodiment, the interlocking components8920extend about the circumference of the hard stop structure8900and therefore provide stop surfaces at various locations about the circumference of the hard stop structure8900. With this configuration, the interlocking components8920can limit the displacement of the hard stop structure8900(and beam) in all directions of lateral forces imparted on the hard stop structure8900(i.e., lateral forces in the X-direction, the Y-direction, or having any component in the X- or Y-direction). Thus, when a force F (as shown inFIG.21) is imparted on the distal end of the medical device8400, causing the hard stop structure8900and beam to bend, interlocking components on both the top side TS and bottom side BS of the hard stop structure8900can engage (i.e., the opposing surfaces of the interlocking components contact each other) to prevent further bending or displacing on both the compression side and the tension side of the hard stop structure8900(and beam). Thus, as with the previous embodiment, the hard stop structure8900provides a reactive moment instead of a single reactive force once the hard stop surfaces engage.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods and/or schematics described above indicate certain events and/or flow patterns occurring in certain order, the ordering of certain events and/or operations may be modified. While the embodiments have been particularly shown and described, it will be understood that various changes in form and details may be made.

For example, any of the instruments described herein (and the components therein) are optionally parts of a surgical assembly that performs minimally invasive surgical procedures, and which can include a manipulator unit, a series of kinematic linkages, a series of cannulas, or the like. Thus, any of the instruments described herein can be used in any suitable surgical system, such as the MIRS system1000shown and described above. Moreover, any of the instruments shown and described herein can be used to manipulate target tissue during a surgical procedure. Such target tissue can be cancer cells, tumor cells, lesions, vascular occlusions, thrombosis, calculi, uterine fibroids, bone metastases, adenomyosis, or any other bodily tissue. The presented examples of target tissue are not an exhaustive list. Moreover, a target structure can also include an artificial substance (or non-tissue) within or associated with a body, such as for example, a stent, a portion of an artificial tube, a fastener within the body or the like.

For example, any of the components of a surgical instrument as described herein can be constructed from any material, such as medical grade stainless steel, nickel alloys, titanium alloys or the like. Further, any of the links, tool members, beams, shafts, cables, or other components described herein can be constructed from multiple pieces that are later joined together. For example, in some embodiments, a link can be constructed by joining together separately constructed components. In other embodiments however, any of the links, tool members, beams, shafts, cables, or components described herein can be monolithically constructed.

Although the instruments are generally shown as having an axis of rotation of the tool members (e.g., axis A2) that is normal to an axis of rotation of the wrist member (e.g., axis A1), in other embodiments any of the instruments described herein can include a tool member axis of rotation that is offset from the axis of rotation of the wrist assembly by any suitable angle.

Although some embodiments show strain sensors (e.g.,830,2830,3830,4830) as being on a single side of the beam (e.g.,810,2810,3810,4810) and other embodiments show strain sensors (e.g.,7830) on multiple sides of the beam (e.g.,7810), it should be understood that any of the embodiments can include one or more strain sensors on either a single side of the beam or on multiple sides of the beam. Further examples of an instrument with strain sensors on a single side of the beam are shown in International Patent Application No. PCT/US2020/060636, filed Nov. 15, 2020, which is incorporated herein by reference.

Although various embodiments have been described as having particular features and/or combinations of components, other embodiments are possible having a combination of any features and/or components from any of embodiments as discussed above. Aspects have been described in the general context of medical devices, and more specifically surgical instruments, but inventive aspects are not necessarily limited to use in medical devices.