# Patent

## Title
Braid-reinforced insulation sheath

## Abstract

Certain aspects relate to silicone sheaths for insulating wristed, electrically conductive instruments. The electrically conductive instruments can include monopolar instruments. The sheaths that are provided can include an internal, tear-resistant braided structure.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of priority to U.S. Provisional Application No. 62/927,618, filed Oct. 29, 2019, the entire contents of which are incorporated by reference herein.


TECHNICAL FIELD
The systems and methods disclosed herein are directed to insulation sheaths, and more particularly to braid-reinforced sheaths for wristed instruments.
BACKGROUND
Manual and robotically controlled surgical instruments include an articulable wrist for controlling an end effector. For wristed, electrically conductive instruments (such as monopolar instruments), the end effector is designed to cut or cauterize tissue using electric current. For such instruments, it is desirable to limit the current pathway to patient tissue to the end effector of the robotic instrument. While mechanisms exist to limit the current pathway, such as via the use of sheaths, such mechanisms often have structural deficiencies.
SUMMARY
For wristed, monopolar instruments, it is the end effector, or specified portion(s) thereof that are expected to interact with patient tissue and should therefore be formed of conductive (e.g., metallic) materials. Current can pass from the conductive end effector to patient tissue to cut or cauterize tissue. In instrument types used under higher loads, wrist components also tend to comprise metal. Accordingly, the wrist components can be insulated with a sheath. The sheaths can be formed of an elastomer to accommodate the range of motions required by wristed instruments. The surgical environment also requires the sheath be resistant to high temperatures due to the proximity to electrical arcs and/or steam from desiccated/burning tissue. Tears can also form due to impacts or abrasions with other instruments, cannula, and pinching from the wrist components. While the sheath can be replaceable, close monitoring of the sheath is not always practicable. For example, in laparoscopic surgery the wrist joint and sheath may not always be within the field of view of the camera. The insulative properties of the sheath can be compromised due to the tears and/or if the sheath slips off the wrist during surgery.
Approaches to retain sheath-like insulation on wrists include a tight fit, which can make installation of the sheath difficult and potentially dangerous. For example, the sheath can be installed in a motion that loads the hands towards the tip of the end effector (e.g., blades). Removing the sheath may also be difficult, particularly after the sheath has been coated in fats and fluids from surgery. Blades may be used to remove the sheath, but this can damage the wrist structures on an instrument wrist that should have multiple uses. Accordingly, a need exists for an improved sheath for a wristed instrument.
One aspect of the present disclosure is realization of a need for an improved insulation sheath for a wristed instrument. The improved sheath can include an internal reinforced mesh or braided structure. The braided structure can include a plurality of interwoven strands or filaments that are then covered and coated with a silicone material. The braided structure can prevent tear propagation, but will allow for the insulation sheath to be flexible and easily installed on the wrist portion of the instrument. In another aspect, the sheath can include an internal ring for improved coupling with the wrist joint.
Described herein is a robotic surgical system that includes a robotic arm including an instrument driver. The instrument driver includes one or more drive inputs coupled to respective pull wires. A conductive instrument includes an elongate shaft coupled with the instrument driver and an end effector. A wrist joint connects the elongate shaft with the end effector. The pull wires couple with the wrist joint and configured to articulate the end effector with respect to the elongate shaft. A sheath insulates the wrist joint. The sheath includes a tubular portion includes an insulative material and an internal support structure. The end effector and the wrist joint each comprise a conductive material.
In another aspect, the end effector and the wrist joint each include a conductive material.
In another aspect, the conductive instrument is a monopolar instrument.
In another aspect, the conductive instrument is a laparoscopic instrument.
In another aspect, the insulative material is a silicone material.
In another aspect, the internal support structure is encased within the silicone material.
In another aspect, the sheath further includes a conical portion configured to cover a base of the end effector.
In another aspect, the internal support structure extends into the conical portion.
In another aspect, a distal end of the sheath has opening with a diameter smaller than an opening of a proximal end of the sheath.
In another aspect, the proximal end of the sheath extends at least partially over the elongate shaft
In another aspect, the tubular portion includes an internal ring and the wrist joint includes a corresponds ring that retains the sheath in position on the wrist joint.
In another aspect, the internal support structure is a braided structure formed of interwoven strands.
In another aspect, the interwoven strands of the braided structure comprise monofilament.
In another aspect, the interwoven strands of the braided structure are multifilament.
In another aspect, the interwoven strands of the braided structure are circular in cross section.
In another aspect, the interwoven strands of the braided structure are generally flat in cross section.
In another aspect, the interwoven strands of the braided structure comprise polypropylene.
In another aspect, the interwoven strands of the braided structure comprise nylon.
In another aspect, the braided structure includes one of a 1:1, 2:1, and 2:2 braid pattern.
In another aspect, a diameter of the tubular portion varies from a first end to a second end of the tubular portion and is configured to match contours of the wrist joint.
In another aspect, the wrist joint includes a proximal clevis, an intermediate clevis and a distal clevis.
A conductive instrument for a robotic surgical system includes an elongate shaft configured to couple with the instrument driver and an end effector. A wrist joint connects the elongate shaft with the end effector. One or more pull wires are anchored with the wrist joint and configured to articulate the end effector with respect to the elongate shaft. A sheath insulates the wrist joint, the sheath includes a tubular portion includes a silicone material and an internal braided structure, the internal braided structure formed of interwoven strands of a polymer material. The end effector and the wrist joint each comprise a conductive material.
In another aspect, the conductive instrument is a monopolar, laparoscopic instrument.
In another aspect, the internal braided structure is encased within the silicone material.
In another aspect, the sheath further includes a conical portion configured to cover a base of the end effector.
In another aspect the internal braided structure extends into the conical portion.
In another aspect, the tubular portion includes an internal ring configured to engage with a corresponding ring on the wrist joint to retain the sheath in position on the wrist joint.
An insulation sheath for a wrist joint of a conductive instrument includes an insulative portion. The insulative portion includes a tubular portion and a conical portion. An internal structure includes a plurality of interwoven strands. The internal structure is encased within the tubular portion of the insulative portion.
In another aspect, the insulative portion comprises a silicone material.
In another aspect, the internal structure extends within the tubular portion and the conical portion.
In another aspect, the tubular portion includes an internal ring configured to engage with a corresponding ring on the wrist joint to retain the sheath in position on the wrist joint.
In another aspect, the interwoven strands of the braided structure comprise monofilament.
In another aspect, the interwoven strands form a braided structure.
In another aspect, the interwoven strands are circular in cross section.
In another aspect, the interwoven strands are generally flat in cross section.
In another aspect, the interwoven strands comprise polypropylene.
In another aspect, the interwoven strands comprise nylon.
In another aspect, the interwoven strands are in one of a 1:1, 2:1, and 2:2 braid pattern.



BRIEF DESCRIPTION OF THE DRAWINGS
The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements.
FIG. 1 illustrates an embodiment of a cart-based robotic system arranged for diagnostic and/or therapeutic bronchoscopy.
FIG. 2 depicts further aspects of the robotic system of FIG. 1.
FIG. 3 illustrates an embodiment of the robotic system of FIG. 1 arranged for ureteroscopy.
FIG. 4 illustrates an embodiment of the robotic system of FIG. 1 arranged for a vascular procedure.
FIG. 5 illustrates an embodiment of a table-based robotic system arranged for a bronchoscopic procedure.
FIG. 6 provides an alternative view of the robotic system of FIG. 5.
FIG. 7 illustrates an example system configured to stow robotic arm(s).
FIG. 8 illustrates an embodiment of a table-based robotic system configured for a ureteroscopic procedure.
FIG. 9 illustrates an embodiment of a table-based robotic system configured for a laparoscopic procedure.
FIG. 10 illustrates an embodiment of the table-based robotic system of FIGS. 5-9 with pitch or tilt adjustment.
FIG. 11 provides a detailed illustration of the interface between the table and the column of the table-based robotic system of FIGS. 5-10.
FIG. 12 illustrates an alternative embodiment of a table-based robotic system.
FIG. 13 illustrates an end view of the table-based robotic system of FIG. 12.
FIG. 14 illustrates an end view of a table-based robotic system with robotic arms attached thereto.
FIG. 15 illustrates an exemplary instrument driver.
FIG. 16 illustrates an exemplary medical instrument with a paired instrument driver.
FIG. 17 illustrates an alternative design for an instrument driver and instrument where the axes of the drive units are parallel to the axis of the elongated shaft of the instrument.
FIG. 18 illustrates an instrument having an instrument-based insertion architecture.
FIG. 19 illustrates an exemplary controller.
FIG. 20 depicts a block diagram illustrating a localization system that estimates a location of one or more elements of the robotic systems of FIGS. 1-10, such as the location of the instrument of FIGS. 16-18, in accordance to an example embodiment.
FIG. 21A shows a robotic arm for controlling a wristed instrument;
FIG. 21B shows the robotic arm of FIG. 21A with the wristed instrument in an articulated position;
FIG. 22 shows an exploded view of a wristed instrument and insulation sheath;
FIG. 23A shows an assembled view of the wristed instrument and the insulation sheath;
FIG. 23B shows the wristed instrument of FIG. 23A in an articulated configuration;
FIG. 24 shows a wristed instrument with an insulation sheath in an articulated configuration;
FIG. 25 shows a braided structure for an insulation sheath;
FIGS. 26A-C show braid patterns for the braided structure in FIG. 25;
FIG. 27A shows a side view of an insulation sheath;
FIG. 27B shows a section view taken along the line A-A in FIG. 27A;
FIG. 28A shows a first end view of the insulation sheath of FIG. 27A;
FIG. 28B shows a second end view of the insulation sheath of FIG. 27A;
FIG. 29 shows detail B from FIG. 27B.



DETAILED DESCRIPTION
1. Overview.
Aspects of the present disclosure may be integrated into a robotically-enabled medical system capable of performing a variety of medical procedures, including both minimally invasive, such as laparoscopy, and non-invasive, such as endoscopy, procedures. Among endoscopic procedures, the system may be capable of performing bronchoscopy, ureteroscopy, gastroscopy, etc.
In addition to performing the breadth of procedures, the system may provide additional benefits, such as enhanced imaging and guidance to assist the physician. Additionally, the system may provide the physician with the ability to perform the procedure from an ergonomic position without the need for awkward arm motions and positions. Still further, the system may provide the physician with the ability to perform the procedure with improved ease of use such that one or more of the instruments of the system can be controlled by a single user.
Various embodiments will be described below in conjunction with the drawings for purposes of illustration. It should be appreciated that many other implementations of the disclosed concepts are possible, and various advantages can be achieved with the disclosed implementations. Headings are included herein for reference and to aid in locating various sections. These headings are not intended to limit the scope of the concepts described with respect thereto. Such concepts may have applicability throughout the entire specification.
A. Robotic System—Cart.
The robotically-enabled medical system may be configured in a variety of ways depending on the particular procedure. FIG. 1 illustrates an embodiment of a cart-based robotically-enabled system 10 arranged for a diagnostic and/or therapeutic bronchoscopy. During a bronchoscopy, the system 10 may comprise a cart 11 having one or more robotic arms 12 to deliver a medical instrument, such as a steerable endoscope 13, which may be a procedure-specific bronchoscope for bronchoscopy, to a natural orifice access point (i.e., the mouth of the patient positioned on a table in the present example) to deliver diagnostic and/or therapeutic tools. As shown, the cart 11 may be positioned proximate to the patient's upper torso in order to provide access to the access point. Similarly, the robotic arms 12 may be actuated to position the bronchoscope relative to the access point. The arrangement in FIG. 1 may also be utilized when performing a gastro-intestinal (GI) procedure with a gastroscope, a specialized endoscope for GI procedures. FIG. 2 depicts an example embodiment of the cart in greater detail.
With continued reference to FIG. 1, once the cart 11 is properly positioned, the robotic arms 12 may insert the steerable endoscope 13 into the patient robotically, manually, or a combination thereof. As shown, the steerable endoscope 13 may comprise at least two telescoping parts, such as an inner leader portion and an outer sheath portion, each portion coupled to a separate instrument driver from the set of instrument drivers 28, each instrument driver coupled to the distal end of an individual robotic arm. This linear arrangement of the instrument drivers 28, which facilitates coaxially aligning the leader portion with the sheath portion, creates a “virtual rail” 29 that may be repositioned in space by manipulating the one or more robotic arms 12 into different angles and/or positions. The virtual rails described herein are depicted in the Figures using dashed lines, and accordingly the dashed lines do not depict any physical structure of the system. Translation of the instrument drivers 28 along the virtual rail 29 telescopes the inner leader portion relative to the outer sheath portion or advances or retracts the endoscope 13 from the patient. The angle of the virtual rail 29 may be adjusted, translated, and pivoted based on clinical application or physician preference. For example, in bronchoscopy, the angle and position of the virtual rail 29 as shown represents a compromise between providing physician access to the endoscope 13 while minimizing friction that results from bending the endoscope 13 into the patient's mouth.
The endoscope 13 may be directed down the patient's trachea and lungs after insertion using precise commands from the robotic system until reaching the target destination or operative site. In order to enhance navigation through the patient's lung network and/or reach the desired target, the endoscope 13 may be manipulated to telescopically extend the inner leader portion from the outer sheath portion to obtain enhanced articulation and greater bend radius. The use of separate instrument drivers 28 also allows the leader portion and sheath portion to be driven independently of each other.
For example, the endoscope 13 may be directed to deliver a biopsy needle to a target, such as, for example, a lesion or nodule within the lungs of a patient. The needle may be deployed down a working channel that runs the length of the endoscope to obtain a tissue sample to be analyzed by a pathologist. Depending on the pathology results, additional tools may be deployed down the working channel of the endoscope for additional biopsies. After identifying a nodule to be malignant, the endoscope 13 may endoscopically deliver tools to resect the potentially cancerous tissue. In some instances, diagnostic and therapeutic treatments can be delivered in separate procedures. In those circumstances, the endoscope 13 may also be used to deliver a fiducial to “mark” the location of the target nodule as well. In other instances, diagnostic and therapeutic treatments may be delivered during the same procedure.
The system 10 may also include a movable tower 30, which may be connected via support cables to the cart 11 to provide support for controls, electronics, fluidics, optics, sensors, and/or power to the cart 11. Placing such functionality in the tower 30 allows for a smaller form factor cart 11 that may be more easily adjusted and/or re-positioned by an operating physician and his/her staff. Additionally, the division of functionality between the cart/table and the support tower 30 reduces operating room clutter and facilitates improving clinical workflow. While the cart 11 may be positioned close to the patient, the tower 30 may be stowed in a remote location to stay out of the way during a procedure.
In support of the robotic systems described above, the tower 30 may include component(s) of a computer-based control system that stores computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, etc. The execution of those instructions, whether the execution occurs in the tower 30 or the cart 11, may control the entire system or sub-system(s) thereof. For example, when executed by a processor of the computer system, the instructions may cause the components of the robotics system to actuate the relevant carriages and arm mounts, actuate the robotics arms, and control the medical instruments. For example, in response to receiving the control signal, the motors in the joints of the robotics arms may position the arms into a certain posture.
The tower 30 may also include a pump, flow meter, valve control, and/or fluid access in order to provide controlled irrigation and aspiration capabilities to the system that may be deployed through the endoscope 13. These components may also be controlled using the computer system of the tower 30. In some embodiments, irrigation and aspiration capabilities may be delivered directly to the endoscope 13 through separate cable(s).
The tower 30 may include a voltage and surge protector designed to provide filtered and protected electrical power to the cart 11, thereby avoiding placement of a power transformer and other auxiliary power components in the cart 11, resulting in a smaller, more moveable cart 11.
The tower 30 may also include support equipment for the sensors deployed throughout the robotic system 10. For example, the tower 30 may include optoelectronics equipment for detecting, receiving, and processing data received from the optical sensors or cameras throughout the robotic system 10. In combination with the control system, such optoelectronics equipment may be used to generate real-time images for display in any number of consoles deployed throughout the system, including in the tower 30. Similarly, the tower 30 may also include an electronic subsystem for receiving and processing signals received from deployed electromagnetic (EM) sensors. The tower 30 may also be used to house and position an EM field generator for detection by EM sensors in or on the medical instrument.
The tower 30 may also include a console 31 in addition to other consoles available in the rest of the system, e.g., console mounted on top of the cart. The console 31 may include a user interface and a display screen, such as a touchscreen, for the physician operator. Consoles in the system 10 are generally designed to provide both robotic controls as well as preoperative and real-time information of the procedure, such as navigational and localization information of the endoscope 13. When the console 31 is not the only console available to the physician, it may be used by a second operator, such as a nurse, to monitor the health or vitals of the patient and the operation of the system 10, as well as to provide procedure-specific data, such as navigational and localization information. In other embodiments, the console 30 is housed in a body that is separate from the tower 30.
The tower 30 may be coupled to the cart 11 and endoscope 13 through one or more cables or connections (not shown). In some embodiments, the support functionality from the tower 30 may be provided through a single cable to the cart 11, simplifying and de-cluttering the operating room. In other embodiments, specific functionality may be coupled in separate cabling and connections. For example, while power may be provided through a single power cable to the cart 11, the support for controls, optics, fluidics, and/or navigation may be provided through a separate cable.
FIG. 2 provides a detailed illustration of an embodiment of the cart 11 from the cart-based robotically-enabled system shown in FIG. 1. The cart 11 generally includes an elongated support structure 14 (often referred to as a “column”), a cart base 15, and a console 16 at the top of the column 14. The column 14 may include one or more carriages, such as a carriage 17 (alternatively “arm support”) for supporting the deployment of one or more robotic arms 12 (three shown in FIG. 2). The carriage 17 may include individually configurable arm mounts that rotate along a perpendicular axis to adjust the base of the robotic arms 12 for better positioning relative to the patient. The carriage 17 also includes a carriage interface 19 that allows the carriage 17 to vertically translate along the column 14.
The carriage interface 19 is connected to the column 14 through slots, such as slot 20, that are positioned on opposite sides of the column 14 to guide the vertical translation of the carriage 17. The slot 20 contains a vertical translation interface to position and hold the carriage 17 at various vertical heights relative to the cart base 15. Vertical translation of the carriage 17 allows the cart 11 to adjust the reach of the robotic arms 12 to meet a variety of table heights, patient sizes, and physician preferences. Similarly, the individually configurable arm mounts on the carriage 17 allow the robotic arm base 21 of the robotic arms 12 to be angled in a variety of configurations.
In some embodiments, the slot 20 may be supplemented with slot covers that are flush and parallel to the slot surface to prevent dirt and fluid ingress into the internal chambers of the column 14 and the vertical translation interface as the carriage 17 vertically translates. The slot covers may be deployed through pairs of spring spools positioned near the vertical top and bottom of the slot 20. The covers are coiled within the spools until deployed to extend and retract from their coiled state as the carriage 17 vertically translates up and down. The spring-loading of the spools provides force to retract the cover into a spool when the carriage 17 translates towards the spool, while also maintaining a tight seal when the carriage 17 translates away from the spool. The covers may be connected to the carriage 17 using, for example, brackets in the carriage interface 19 to ensure proper extension and retraction of the cover as the carriage 17 translates.
The column 14 may internally comprise mechanisms, such as gears and motors, that are designed to use a vertically aligned lead screw to translate the carriage 17 in a mechanized fashion in response to control signals generated in response to user inputs, e.g., inputs from the console 16.
The robotic arms 12 may generally comprise robotic arm bases 21 and end effectors 22, separated by a series of linkages 23 that are connected by a series of joints 24, each joint comprising an independent actuator, each actuator comprising an independently controllable motor. Each independently controllable joint represents an independent degree of freedom available to the robotic arm 12. Each of the robotic arms 12 may have seven joints, and thus provide seven degrees of freedom. A multitude of joints result in a multitude of degrees of freedom, allowing for “redundant” degrees of freedom. Having redundant degrees of freedom allows the robotic arms 12 to position their respective end effectors 22 at a specific position, orientation, and trajectory in space using different linkage positions and joint angles. This allows for the system to position and direct a medical instrument from a desired point in space while allowing the physician to move the arm joints into a clinically advantageous position away from the patient to create greater access, while avoiding arm collisions.
The cart base 15 balances the weight of the column 14, carriage 17, and robotic arms 12 over the floor. Accordingly, the cart base 15 houses heavier components, such as electronics, motors, power supply, as well as components that either enable movement and/or immobilize the cart 11. For example, the cart base 15 includes rollable wheel-shaped casters 25 that allow for the cart 11 to easily move around the room prior to a procedure. After reaching the appropriate position, the casters 25 may be immobilized using wheel locks to hold the cart 11 in place during the procedure.
Positioned at the vertical end of the column 14, the console 16 allows for both a user interface for receiving user input and a display screen (or a dual-purpose device such as, for example, a touchscreen 26) to provide the physician user with both preoperative and intraoperative data. Potential preoperative data on the touchscreen 26 may include preoperative plans, navigation and mapping data derived from preoperative computerized tomography (CT) scans, and/or notes from preoperative patient interviews. Intraoperative data on display may include optical information provided from the tool, sensor and coordinate information from sensors, as well as vital patient statistics, such as respiration, heart rate, and/or pulse. The console 16 may be positioned and tilted to allow a physician to access the console 16 from the side of the column 14 opposite the carriage 17. From this position, the physician may view the console 16, robotic arms 12, and patient while operating the console 16 from behind the cart 11. As shown, the console 16 also includes a handle 27 to assist with maneuvering and stabilizing the cart 11.
FIG. 3 illustrates an embodiment of a robotically-enabled system 10 arranged for ureteroscopy. In a ureteroscopic procedure, the cart 11 may be positioned to deliver a ureteroscope 32, a procedure-specific endoscope designed to traverse a patient's urethra and ureter, to the lower abdominal area of the patient. In a ureteroscopy, it may be desirable for the ureteroscope 32 to be directly aligned with the patient's urethra to reduce friction and forces on the sensitive anatomy in the area. As shown, the cart 11 may be aligned at the foot of the table to allow the robotic arms 12 to position the ureteroscope 32 for direct linear access to the patient's urethra. From the foot of the table, the robotic arms 12 may insert the ureteroscope 32 along the virtual rail 33 directly into the patient's lower abdomen through the urethra.
After insertion into the urethra, using similar control techniques as in bronchoscopy, the ureteroscope 32 may be navigated into the bladder, ureters, and/or kidneys for diagnostic and/or therapeutic applications. For example, the ureteroscope 32 may be directed into the ureter and kidneys to break up kidney stone build up using a laser or ultrasonic lithotripsy device deployed down the working channel of the ureteroscope 32. After lithotripsy is complete, the resulting stone fragments may be removed using baskets deployed down the ureteroscope 32.
FIG. 4 illustrates an embodiment of a robotically-enabled system 10 similarly arranged for a vascular procedure. In a vascular procedure, the system 10 may be configured such that the cart 11 may deliver a medical instrument 34, such as a steerable catheter, to an access point in the femoral artery in the patient's leg. The femoral artery presents both a larger diameter for navigation as well as a relatively less circuitous and tortuous path to the patient's heart, which simplifies navigation. As in a ureteroscopic procedure, the cart 11 may be positioned towards the patient's legs and lower abdomen to allow the robotic arms 12 to provide a virtual rail 35 with direct linear access to the femoral artery access point in the patient's thigh/hip region. After insertion into the artery, the medical instrument 34 may be directed and inserted by translating the instrument drivers 28. Alternatively, the cart may be positioned around the patient's upper abdomen in order to reach alternative vascular access points, such as, for example, the carotid and brachial arteries near the shoulder and wrist.
B. Robotic System—Table.
Embodiments of the robotically-enabled medical system may also incorporate the patient's table. Incorporation of the table reduces the amount of capital equipment within the operating room by removing the cart, which allows greater access to the patient. FIG. 5 illustrates an embodiment of such a robotically-enabled system arranged for a bronchoscopic procedure. System 36 includes a support structure or column 37 for supporting platform 38 (shown as a “table” or “bed”) over the floor. Much like in the cart-based systems, the end effectors of the robotic arms 39 of the system 36 comprise instrument drivers 42 that are designed to manipulate an elongated medical instrument, such as a bronchoscope 40 in FIG. 5, through or along a virtual rail 41 formed from the linear alignment of the instrument drivers 42. In practice, a C-arm for providing fluoroscopic imaging may be positioned over the patient's upper abdominal area by placing the emitter and detector around the table 38.
FIG. 6 provides an alternative view of the system 36 without the patient and medical instrument for discussion purposes. As shown, the column 37 may include one or more carriages 43 shown as ring-shaped in the system 36, from which the one or more robotic arms 39 may be based. The carriages 43 may translate along a vertical column interface 44 that runs the length of the column 37 to provide different vantage points from which the robotic arms 39 may be positioned to reach the patient. The carriage(s) 43 may rotate around the column 37 using a mechanical motor positioned within the column 37 to allow the robotic arms 39 to have access to multiples sides of the table 38, such as, for example, both sides of the patient. In embodiments with multiple carriages, the carriages may be individually positioned on the column and may translate and/or rotate independently of the other carriages. While the carriages 43 need not surround the column 37 or even be circular, the ring-shape as shown facilitates rotation of the carriages 43 around the column 37 while maintaining structural balance. Rotation and translation of the carriages 43 allows the system 36 to align the medical instruments, such as endoscopes and laparoscopes, into different access points on the patient. In other embodiments (not shown), the system 36 can include a patient table or bed with adjustable arm supports in the form of bars or rails extending alongside it. One or more robotic arms 39 (e.g., via a shoulder with an elbow joint) can be attached to the adjustable arm supports, which can be vertically adjusted. By providing vertical adjustment, the robotic arms 39 are advantageously capable of being stowed compactly beneath the patient table or bed, and subsequently raised during a procedure.
The robotic arms 39 may be mounted on the carriages 43 through a set of arm mounts 45 comprising a series of joints that may individually rotate and/or telescopically extend to provide additional configurability to the robotic arms 39. Additionally, the arm mounts 45 may be positioned on the carriages 43 such that, when the carriages 43 are appropriately rotated, the arm mounts 45 may be positioned on either the same side of the table 38 (as shown in FIG. 6), on opposite sides of the table 38 (as shown in FIG. 9), or on adjacent sides of the table 38 (not shown).
The column 37 structurally provides support for the table 38, and a path for vertical translation of the carriages 43. Internally, the column 37 may be equipped with lead screws for guiding vertical translation of the carriages, and motors to mechanize the translation of the carriages 43 based the lead screws. The column 37 may also convey power and control signals to the carriages 43 and the robotic arms 39 mounted thereon.
The table base 46 serves a similar function as the cart base 15 in the cart 11 shown in FIG. 2, housing heavier components to balance the table/bed 38, the column 37, the carriages 43, and the robotic arms 39. The table base 46 may also incorporate rigid casters to provide stability during procedures. Deployed from the bottom of the table base 46, the casters may extend in opposite directions on both sides of the base 46 and retract when the system 36 needs to be moved.
With continued reference to FIG. 6, the system 36 may also include a tower (not shown) that divides the functionality of the system 36 between the table and the tower to reduce the form factor and bulk of the table. As in earlier disclosed embodiments, the tower may provide a variety of support functionalities to the table, such as processing, computing, and control capabilities, power, fluidics, and/or optical and sensor processing. The tower may also be movable to be positioned away from the patient to improve physician access and de-clutter the operating room. Additionally, placing components in the tower allows for more storage space in the table base 46 for potential stowage of the robotic arms 39. The tower may also include a master controller or console that provides both a user interface for user input, such as keyboard and/or pendant, as well as a display screen (or touchscreen) for preoperative and intraoperative information, such as real-time imaging, navigation, and tracking information. In some embodiments, the tower may also contain holders for gas tanks to be used for insufflation.
In some embodiments, a table base may stow and store the robotic arms when not in use. FIG. 7 illustrates a system 47 that stows robotic arms in an embodiment of the table-based system. In the system 47, carriages 48 may be vertically translated into base 49 to stow robotic arms 50, arm mounts 51, and the carriages 48 within the base 49. Base covers 52 may be translated and retracted open to deploy the carriages 48, arm mounts 51, and robotic arms 50 around column 53, and closed to stow to protect them when not in use. The base covers 52 may be sealed with a membrane 54 along the edges of its opening to prevent dirt and fluid ingress when closed.
FIG. 8 illustrates an embodiment of a robotically-enabled table-based system configured for a ureteroscopic procedure. In a ureteroscopy, the table 38 may include a swivel portion 55 for positioning a patient off-angle from the column 37 and table base 46. The swivel portion 55 may rotate or pivot around a pivot point (e.g., located below the patient's head) in order to position the bottom portion of the swivel portion 55 away from the column 37. For example, the pivoting of the swivel portion 55 allows a C-arm (not shown) to be positioned over the patient's lower abdomen without competing for space with the column (not shown) below table 38. By rotating the carriage 35 (not shown) around the column 37, the robotic arms 39 may directly insert a ureteroscope 56 along a virtual rail 57 into the patient's groin area to reach the urethra. In a ureteroscopy, stirrups 58 may also be fixed to the swivel portion 55 of the table 38 to support the position of the patient's legs during the procedure and allow clear access to the patient's groin area.
In a laparoscopic procedure, through small incision(s) in the patient's abdominal wall, minimally invasive instruments may be inserted into the patient's anatomy. In some embodiments, the minimally invasive instruments comprise an elongated rigid member, such as a shaft, which is used to access anatomy within the patient. After inflation of the patient's abdominal cavity, the instruments may be directed to perform surgical or medical tasks, such as grasping, cutting, ablating, suturing, etc. In some embodiments, the instruments can comprise a scope, such as a laparoscope. FIG. 9 illustrates an embodiment of a robotically-enabled table-based system configured for a laparoscopic procedure. As shown in FIG. 9, the carriages 43 of the system 36 may be rotated and vertically adjusted to position pairs of the robotic arms 39 on opposite sides of the table 38, such that instrument 59 may be positioned using the arm mounts 45 to be passed through minimal incisions on both sides of the patient to reach his/her abdominal cavity.
To accommodate laparoscopic procedures, the robotically-enabled table system may also tilt the platform to a desired angle. FIG. 10 illustrates an embodiment of the robotically-enabled medical system with pitch or tilt adjustment. As shown in FIG. 10, the system 36 may accommodate tilt of the table 38 to position one portion of the table at a greater distance from the floor than the other. Additionally, the arm mounts 45 may rotate to match the tilt such that the robotic arms 39 maintain the same planar relationship with the table 38. To accommodate steeper angles, the column 37 may also include telescoping portions 60 that allow vertical extension of the column 37 to keep the table 38 from touching the floor or colliding with the table base 46.
FIG. 11 provides a detailed illustration of the interface between the table 38 and the column 37. Pitch rotation mechanism 61 may be configured to alter the pitch angle of the table 38 relative to the column 37 in multiple degrees of freedom. The pitch rotation mechanism 61 may be enabled by the positioning of orthogonal axes 1, 2 at the column-table interface, each axis actuated by a separate motor 3, 4 responsive to an electrical pitch angle command. Rotation along one screw 5 would enable tilt adjustments in one axis 1, while rotation along the other screw 6 would enable tilt adjustments along the other axis 2. In some embodiments, a ball joint can be used to alter the pitch angle of the table 38 relative to the column 37 in multiple degrees of freedom.
For example, pitch adjustments are particularly useful when trying to position the table in a Trendelenburg position, i.e., position the patient's lower abdomen at a higher position from the floor than the patient's upper abdomen, for lower abdominal surgery. The Trendelenburg position causes the patient's internal organs to slide towards his/her upper abdomen through the force of gravity, clearing out the abdominal cavity for minimally invasive tools to enter and perform lower abdominal surgical or medical procedures, such as laparoscopic prostatectomy.
FIGS. 12 and 13 illustrate isometric and end views of an alternative embodiment of a table-based surgical robotics system 100. The surgical robotics system 100 includes one or more adjustable arm supports 105 that can be configured to support one or more robotic arms (see, for example, FIG. 14) relative to a table 101. In the illustrated embodiment, a single adjustable arm support 105 is shown, though an additional arm support can be provided on an opposite side of the table 101. The adjustable arm support 105 can be configured so that it can move relative to the table 101 to adjust and/or vary the position of the adjustable arm support 105 and/or any robotic arms mounted thereto relative to the table 101. For example, the adjustable arm support 105 may be adjusted one or more degrees of freedom relative to the table 101. The adjustable arm support 105 provides high versatility to the system 100, including the ability to easily stow the one or more adjustable arm supports 105 and any robotics arms attached thereto beneath the table 101. The adjustable arm support 105 can be elevated from the stowed position to a position below an upper surface of the table 101. In other embodiments, the adjustable arm support 105 can be elevated from the stowed position to a position above an upper surface of the table 101.
The adjustable arm support 105 can provide several degrees of freedom, including lift, lateral translation, tilt, etc. In the illustrated embodiment of FIGS. 12 and 13, the arm support 105 is configured with four degrees of freedom, which are illustrated with arrows in FIG. 12. A first degree of freedom allows for adjustment of the adjustable arm support 105 in the z-direction (“Z-lift”). For example, the adjustable arm support 105 can include a carriage 109 configured to move up or down along or relative to a column 102 supporting the table 101. A second degree of freedom can allow the adjustable arm support 105 to tilt. For example, the adjustable arm support 105 can include a rotary joint, which can allow the adjustable arm support 105 to be aligned with the bed in a Trendelenburg position. A third degree of freedom can allow the adjustable arm support 105 to “pivot up,” which can be used to adjust a distance between a side of the table 101 and the adjustable arm support 105. A fourth degree of freedom can permit translation of the adjustable arm support 105 along a longitudinal length of the table.
The surgical robotics system 100 in FIGS. 12 and 13 can comprise a table supported by a column 102 that is mounted to a base 103. The base 103 and the column 102 support the table 101 relative to a support surface. A floor axis 131 and a support axis 133 are shown in FIG. 13.
The adjustable arm support 105 can be mounted to the column 102. In other embodiments, the arm support 105 can be mounted to the table 101 or base 103. The adjustable arm support 105 can include a carriage 109, a bar or rail connector 111 and a bar or rail 107. In some embodiments, one or more robotic arms mounted to the rail 107 can translate and move relative to one another.
The carriage 109 can be attached to the column 102 by a first joint 113, which allows the carriage 109 to move relative to the column 102 (e.g., such as up and down a first or vertical axis 123). The first joint 113 can provide the first degree of freedom (“Z-lift”) to the adjustable arm support 105. The adjustable arm support 105 can include a second joint 115, which provides the second degree of freedom (tilt) for the adjustable arm support 105. The adjustable arm support 105 can include a third joint 117, which can provide the third degree of freedom (“pivot up”) for the adjustable arm support 105. An additional joint 119 (shown in FIG. 13) can be provided that mechanically constrains the third joint 117 to maintain an orientation of the rail 107 as the rail connector 111 is rotated about a third axis 127. The adjustable arm support 105 can include a fourth joint 121, which can provide a fourth degree of freedom (translation) for the adjustable arm support 105 along a fourth axis 129.
FIG. 14 illustrates an end view of the surgical robotics system 140A with two adjustable arm supports 105A, 105B mounted on opposite sides of a table 101. A first robotic arm 142A is attached to the bar or rail 107A of the first adjustable arm support 105B. The first robotic arm 142A includes a base 144A attached to the rail 107A. The distal end of the first robotic arm 142A includes an instrument drive mechanism 146A that can attach to one or more robotic medical instruments or tools. Similarly, the second robotic arm 142B includes a base 144B attached to the rail 107B. The distal end of the second robotic arm 142B includes an instrument drive mechanism 146B. The instrument drive mechanism 146B can be configured to attach to one or more robotic medical instruments or tools.
In some embodiments, one or more of the robotic arms 142A, 142B comprises an arm with seven or more degrees of freedom. In some embodiments, one or more of the robotic arms 142A, 142B can include eight degrees of freedom, including an insertion axis (1-degree of freedom including insertion), a wrist (3-degrees of freedom including wrist pitch, yaw and roll), an elbow (1-degree of freedom including elbow pitch), a shoulder (2-degrees of freedom including shoulder pitch and yaw), and base 144A, 144B (1-degree of freedom including translation). In some embodiments, the insertion degree of freedom can be provided by the robotic arm 142A, 142B, while in other embodiments, the instrument itself provides insertion via an instrument-based insertion architecture.
C. Instrument Driver & Interface.
The end effectors of the system's robotic arms may comprise (i) an instrument driver (alternatively referred to as “instrument drive mechanism” or “instrument device manipulator”) that incorporates electro-mechanical means for actuating the medical instrument and (ii) a removable or detachable medical instrument, which may be devoid of any electro-mechanical components, such as motors. This dichotomy may be driven by the need to sterilize medical instruments used in medical procedures, and the inability to adequately sterilize expensive capital equipment due to their intricate mechanical assemblies and sensitive electronics. Accordingly, the medical instruments may be designed to be detached, removed, and interchanged from the instrument driver (and thus the system) for individual sterilization or disposal by the physician or the physician's staff. In contrast, the instrument drivers need not be changed or sterilized, and may be draped for protection.
FIG. 15 illustrates an example instrument driver. Positioned at the distal end of a robotic arm, instrument driver 62 comprises one or more drive units 63 arranged with parallel axes to provide controlled torque to a medical instrument via drive shafts 64. Each drive unit 63 comprises an individual drive shaft 64 for interacting with the instrument, a gear head 65 for converting the motor shaft rotation to a desired torque, a motor 66 for generating the drive torque, an encoder 67 to measure the speed of the motor shaft and provide feedback to the control circuitry, and control circuitry 68 for receiving control signals and actuating the drive unit. Each drive unit 63 being independently controlled and motorized, the instrument driver 62 may provide multiple (e.g., four as shown in FIG. 15) independent drive outputs to the medical instrument. In operation, the control circuitry 68 would receive a control signal, transmit a motor signal to the motor 66, compare the resulting motor speed as measured by the encoder 67 with the desired speed, and modulate the motor signal to generate the desired torque.
For procedures that require a sterile environment, the robotic system may incorporate a drive interface, such as a sterile adapter connected to a sterile drape, that sits between the instrument driver and the medical instrument. The chief purpose of the sterile adapter is to transfer angular motion from the drive shafts of the instrument driver to the drive inputs of the instrument while maintaining physical separation, and thus sterility, between the drive shafts and drive inputs. Accordingly, an example sterile adapter may comprise a series of rotational inputs and outputs intended to be mated with the drive shafts of the instrument driver and drive inputs on the instrument. Connected to the sterile adapter, the sterile drape, comprised of a thin, flexible material such as transparent or translucent plastic, is designed to cover the capital equipment, such as the instrument driver, robotic arm, and cart (in a cart-based system) or table (in a table-based system). Use of the drape would allow the capital equipment to be positioned proximate to the patient while still being located in an area not requiring sterilization (i.e., non-sterile field). On the other side of the sterile drape, the medical instrument may interface with the patient in an area requiring sterilization (i.e., sterile field).
D. Medical Instrument.
FIG. 16 illustrates an example medical instrument with a paired instrument driver. Like other instruments designed for use with a robotic system, medical instrument 70 comprises an elongated shaft 71 (or elongate body) and an instrument base 72. The instrument base 72, also referred to as an “instrument handle” due to its intended design for manual interaction by the physician, may generally comprise rotatable drive inputs 73, e.g., receptacles, pulleys or spools, that are designed to be mated with drive outputs 74 that extend through a drive interface on instrument driver 75 at the distal end of robotic arm 76. When physically connected, latched, and/or coupled, the mated drive inputs 73 of the instrument base 72 may share axes of rotation with the drive outputs 74 in the instrument driver 75 to allow the transfer of torque from the drive outputs 74 to the drive inputs 73. In some embodiments, the drive outputs 74 may comprise splines that are designed to mate with receptacles on the drive inputs 73.
The elongated shaft 71 is designed to be delivered through either an anatomical opening or lumen, e.g., as in endoscopy, or a minimally invasive incision, e.g., as in laparoscopy. The elongated shaft 71 may be either flexible (e.g., having properties similar to an endoscope) or rigid (e.g., having properties similar to a laparoscope) or contain a customized combination of both flexible and rigid portions. When designed for laparoscopy, the distal end of a rigid elongated shaft may be connected to an end effector extending from a jointed wrist formed from a clevis with at least one degree of freedom and a surgical tool or medical instrument, such as, for example, a grasper or scissors, that may be actuated based on force from the tendons as the drive inputs rotate in response to torque received from the drive outputs 74 of the instrument driver 75. When designed for endoscopy, the distal end of a flexible elongated shaft may include a steerable or controllable bending section that may be articulated and bent based on torque received from the drive outputs 74 of the instrument driver 75.
Torque from the instrument driver 75 is transmitted down the elongated shaft 71 using tendons along the elongated shaft 71. These individual tendons, such as pull wires, may be individually anchored to individual drive inputs 73 within the instrument handle 72. From the handle 72, the tendons are directed down one or more pull lumens along the elongated shaft 71 and anchored at the distal portion of the elongated shaft 71, or in the wrist at the distal portion of the elongated shaft. During a surgical procedure, such as a laparoscopic, endoscopic or hybrid procedure, these tendons may be coupled to a distally mounted end effector, such as a wrist, grasper, or scissor. Under such an arrangement, torque exerted on drive inputs 73 would transfer tension to the tendon, thereby causing the end effector to actuate in some way. In some embodiments, during a surgical procedure, the tendon may cause a joint to rotate about an axis, thereby causing the end effector to move in one direction or another. Alternatively, the tendon may be connected to one or more jaws of a grasper at the distal end of the elongated shaft 71, where tension from the tendon causes the grasper to close.
In endoscopy, the tendons may be coupled to a bending or articulating section positioned along the elongated shaft 71 (e.g., at the distal end) via adhesive, control ring, or other mechanical fixation. When fixedly attached to the distal end of a bending section, torque exerted on the drive inputs 73 would be transmitted down the tendons, causing the softer, bending section (sometimes referred to as the articulable section or region) to bend or articulate. Along the non-bending sections, it may be advantageous to spiral or helix the individual pull lumens that direct the individual tendons along (or inside) the walls of the endoscope shaft to balance the radial forces that result from tension in the pull wires. The angle of the spiraling and/or spacing therebetween may be altered or engineered for specific purposes, wherein tighter spiraling exhibits lesser shaft compression under load forces, while lower amounts of spiraling results in greater shaft compression under load forces, but limits bending. On the other end of the spectrum, the pull lumens may be directed parallel to the longitudinal axis of the elongated shaft 71 to allow for controlled articulation in the desired bending or articulable sections.
In endoscopy, the elongated shaft 71 houses a number of components to assist with the robotic procedure. The shaft 71 may comprise a working channel for deploying surgical tools (or medical instruments), irrigation, and/or aspiration to the operative region at the distal end of the shaft 71. The shaft 71 may also accommodate wires and/or optical fibers to transfer signals to/from an optical assembly at the distal tip, which may include an optical camera. The shaft 71 may also accommodate optical fibers to carry light from proximally-located light sources, such as light emitting diodes, to the distal end of the shaft 71.
At the distal end of the instrument 70, the distal tip may also comprise the opening of a working channel for delivering tools for diagnostic and/or therapy, irrigation, and aspiration to an operative site. The distal tip may also include a port for a camera, such as a fiberscope or a digital camera, to capture images of an internal anatomical space. Relatedly, the distal tip may also include ports for light sources for illuminating the anatomical space when using the camera.
In the example of FIG. 16, the drive shaft axes, and thus the drive input axes, are orthogonal to the axis of the elongated shaft 71. This arrangement, however, complicates roll capabilities for the elongated shaft 71. Rolling the elongated shaft 71 along its axis while keeping the drive inputs 73 static results in undesirable tangling of the tendons as they extend off the drive inputs 73 and enter pull lumens within the elongated shaft 71. The resulting entanglement of such tendons may disrupt any control algorithms intended to predict movement of the flexible elongated shaft 71 during an endoscopic procedure.
FIG. 17 illustrates an alternative design for an instrument driver and instrument where the axes of the drive units are parallel to the axis of the elongated shaft of the instrument. As shown, a circular instrument driver 80 comprises four drive units with their drive outputs 81 aligned in parallel at the end of a robotic arm 82. The drive units, and their respective drive outputs 81, are housed in a rotational assembly 83 of the instrument driver 80 that is driven by one of the drive units within the assembly 83. In response to torque provided by the rotational drive unit, the rotational assembly 83 rotates along a circular bearing that connects the rotational assembly 83 to the non-rotational portion 84 of the instrument driver 80. Power and controls signals may be communicated from the non-rotational portion 84 of the instrument driver 80 to the rotational assembly 83 through electrical contacts that may be maintained through rotation by a brushed slip ring connection (not shown). In other embodiments, the rotational assembly 83 may be responsive to a separate drive unit that is integrated into the non-rotatable portion 84, and thus not in parallel to the other drive units. The rotational mechanism 83 allows the instrument driver 80 to rotate the drive units, and their respective drive outputs 81, as a single unit around an instrument driver axis 85.
Like earlier disclosed embodiments, an instrument 86 may comprise an elongated shaft portion 88 and an instrument base 87 (shown with a transparent external skin for discussion purposes) comprising a plurality of drive inputs 89 (such as receptacles, pulleys, and spools) that are configured to receive the drive outputs 81 in the instrument driver 80. Unlike prior disclosed embodiments, the instrument shaft 88 extends from the center of the instrument base 87 with an axis substantially parallel to the axes of the drive inputs 89, rather than orthogonal as in the design of FIG. 16.
When coupled to the rotational assembly 83 of the instrument driver 80, the medical instrument 86, comprising instrument base 87 and instrument shaft 88, rotates in combination with the rotational assembly 83 about the instrument driver axis 85. Since the instrument shaft 88 is positioned at the center of instrument base 87, the instrument shaft 88 is coaxial with instrument driver axis 85 when attached. Thus, rotation of the rotational assembly 83 causes the instrument shaft 88 to rotate about its own longitudinal axis. Moreover, as the instrument base 87 rotates with the instrument shaft 88, any tendons connected to the drive inputs 89 in the instrument base 87 are not tangled during rotation. Accordingly, the parallelism of the axes of the drive outputs 81, drive inputs 89, and instrument shaft 88 allows for the shaft rotation without tangling any control tendons.
FIG. 18 illustrates an instrument having an instrument based insertion architecture in accordance with some embodiments. The instrument 150 can be coupled to any of the instrument drivers discussed above. The instrument 150 comprises an elongated shaft 152, an end effector 162 connected to the shaft 152, and a handle 170 coupled to the shaft 152. The elongated shaft 152 comprises a tubular member having a proximal portion 154 and a distal portion 156. The elongated shaft 152 comprises one or more channels or grooves 158 along its outer surface. The grooves 158 are configured to receive one or more wires or cables 180 therethrough. One or more cables 180 thus run along an outer surface of the elongated shaft 152. In other embodiments, cables 180 can also run through the elongated shaft 152. Manipulation of the one or more cables 180 (e.g., via an instrument driver) results in actuation of the end effector 162.
The instrument handle 170, which may also be referred to as an instrument base, may generally comprise an attachment interface 172 having one or more mechanical inputs 174, e.g., receptacles, pulleys or spools, that are designed to be reciprocally mated with one or more torque couplers on an attachment surface of an instrument driver.
In some embodiments, the instrument 150 comprises a series of pulleys or cables that enable the elongated shaft 152 to translate relative to the handle 170. In other words, the instrument 150 itself comprises an instrument-based insertion architecture that accommodates insertion of the instrument, thereby minimizing the reliance on a robot arm to provide insertion of the instrument 150. In other embodiments, a robotic arm can be largely responsible for instrument insertion.
E. Controller.
Any of the robotic systems described herein can include an input device or controller for manipulating an instrument attached to a robotic arm. In some embodiments, the controller can be coupled (e.g., communicatively, electronically, electrically, wirelessly and/or mechanically) with an instrument such that manipulation of the controller causes a corresponding manipulation of the instrument e.g., via master slave control.
FIG. 19 is a perspective view of an embodiment of a controller 182. In the present embodiment, the controller 182 comprises a hybrid controller that can have both impedance and admittance control. In other embodiments, the controller 182 can utilize just impedance or passive control. In other embodiments, the controller 182 can utilize just admittance control. By being a hybrid controller, the controller 182 advantageously can have a lower perceived inertia while in use.
In the illustrated embodiment, the controller 182 is configured to allow manipulation of two medical instruments, and includes two handles 184. Each of the handles 184 is connected to a gimbal 186. Each gimbal 186 is connected to a positioning platform 188.
As shown in FIG. 19, each positioning platform 188 includes a SCARA arm (selective compliance assembly robot arm) 198 coupled to a column 194 by a prismatic joint 196. The prismatic joints 196 are configured to translate along the column 194 (e.g., along rails 197) to allow each of the handles 184 to be translated in the z-direction, providing a first degree of freedom. The SCARA arm 198 is configured to allow motion of the handle 184 in an x-y plane, providing two additional degrees of freedom.
In some embodiments, one or more load cells are positioned in the controller. For example, in some embodiments, a load cell (not shown) is positioned in the body of each of the gimbals 186. By providing a load cell, portions of the controller 182 are capable of operating under admittance control, thereby advantageously reducing the perceived inertia of the controller while in use. In some embodiments, the positioning platform 188 is configured for admittance control, while the gimbal 186 is configured for impedance control. In other embodiments, the gimbal 186 is configured for admittance control, while the positioning platform 188 is configured for impedance control. Accordingly, for some embodiments, the translational or positional degrees of freedom of the positioning platform 188 can rely on admittance control, while the rotational degrees of freedom of the gimbal 186 rely on impedance control.
F. Navigation and Control.
Traditional endoscopy may involve the use of fluoroscopy (e.g., as may be delivered through a C-arm) and other forms of radiation-based imaging modalities to provide endoluminal guidance to an operator physician. In contrast, the robotic systems contemplated by this disclosure can provide for non-radiation-based navigational and localization means to reduce physician exposure to radiation and reduce the amount of equipment within the operating room. As used herein, the term “localization” may refer to determining and/or monitoring the position of objects in a reference coordinate system. Technologies such as preoperative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to achieve a radiation-free operating environment. In other cases, where radiation-based imaging modalities are still used, the preoperative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to improve upon the information obtained solely through radiation-based imaging modalities.
FIG. 20 is a block diagram illustrating a localization system 90 that estimates a location of one or more elements of the robotic system, such as the location of the instrument, in accordance to an example embodiment. The localization system 90 may be a set of one or more computer devices configured to execute one or more instructions. The computer devices may be embodied by a processor (or processors) and computer-readable memory in one or more components discussed above. By way of example and not limitation, the computer devices may be in the tower 30 shown in FIG. 1, the cart 11 shown in FIGS. 1-4, the beds shown in FIGS. 5-14, etc.
As shown in FIG. 20, the localization system 90 may include a localization module 95 that processes input data 91-94 to generate location data 96 for the distal tip of a medical instrument. The location data 96 may be data or logic that represents a location and/or orientation of the distal end of the instrument relative to a frame of reference. The frame of reference can be a frame of reference relative to the anatomy of the patient or to a known object, such as an EM field generator (see discussion below for the EM field generator).
The various input data 91-94 are now described in greater detail. Preoperative mapping may be accomplished through the use of the collection of low dose CT scans. Preoperative CT scans are reconstructed into three-dimensional images, which are visualized, e.g. as “slices” of a cutaway view of the patient's internal anatomy. When analyzed in the aggregate, image-based models for anatomical cavities, spaces and structures of the patient's anatomy, such as a patient lung network, may be generated. Techniques such as center-line geometry may be determined and approximated from the CT images to develop a three-dimensional volume of the patient's anatomy, referred to as model data 91 (also referred to as “preoperative model data” when generated using only preoperative CT scans). The use of center-line geometry is discussed in U.S. patent application Ser. No. 14/523,760, the contents of which are herein incorporated in its entirety. Network topological models may also be derived from the CT-images, and are particularly appropriate for bronchoscopy.
In some embodiments, the instrument may be equipped with a camera to provide vision data (or image data) 92. The localization module 95 may process the vision data 92 to enable one or more vision-based (or image-based) location tracking modules or features. For example, the preoperative model data 91 may be used in conjunction with the vision data 92 to enable computer vision-based tracking of the medical instrument (e.g., an endoscope or an instrument advance through a working channel of the endoscope). For example, using the preoperative model data 91, the robotic system may generate a library of expected endoscopic images from the model based on the expected path of travel of the endoscope, each image linked to a location within the model. Intraoperatively, this library may be referenced by the robotic system in order to compare real-time images captured at the camera (e.g., a camera at a distal end of the endoscope) to those in the image library to assist localization.
Other computer vision-based tracking techniques use feature tracking to determine motion of the camera, and thus the endoscope. Some features of the localization module 95 may identify circular geometries in the preoperative model data 91 that correspond to anatomical lumens and track the change of those geometries to determine which anatomical lumen was selected, as well as the relative rotational and/or translational motion of the camera. Use of a topological map may further enhance vision-based algorithms or techniques.
Optical flow, another computer vision-based technique, may analyze the displacement and translation of image pixels in a video sequence in the vision data 92 to infer camera movement. Examples of optical flow techniques may include motion detection, object segmentation calculations, luminance, motion compensated encoding, stereo disparity measurement, etc. Through the comparison of multiple frames over multiple iterations, movement and location of the camera (and thus the endoscope) may be determined.
The localization module 95 may use real-time EM tracking to generate a real-time location of the endoscope in a global coordinate system that may be registered to the patient's anatomy, represented by the preoperative model. In EM tracking, an EM sensor (or tracker) comprising one or more sensor coils embedded in one or more locations and orientations in a medical instrument (e.g., an endoscopic tool) measures the variation in the EM field created by one or more static EM field generators positioned at a known location. The location information detected by the EM sensors is stored as EM data 93. The EM field generator (or transmitter), may be placed close to the patient to create a low intensity magnetic field that the embedded sensor may detect. The magnetic field induces small currents in the sensor coils of the EM sensor, which may be analyzed to determine the distance and angle between the EM sensor and the EM field generator. These distances and orientations may be intraoperatively “registered” to the patient anatomy (e.g., the preoperative model) in order to determine the geometric transformation that aligns a single location in the coordinate system with a position in the preoperative model of the patient's anatomy. Once registered, an embedded EM tracker in one or more positions of the medical instrument (e.g., the distal tip of an endoscope) may provide real-time indications of the progression of the medical instrument through the patient's anatomy.
Robotic command and kinematics data 94 may also be used by the localization module 95 to provide localization data 96 for the robotic system. Device pitch and yaw resulting from articulation commands may be determined during preoperative calibration. Intraoperatively, these calibration measurements may be used in combination with known insertion depth information to estimate the position of the instrument. Alternatively, these calculations may be analyzed in combination with EM, vision, and/or topological modeling to estimate the position of the medical instrument within the network.
As FIG. 20 shows, a number of other input data can be used by the localization module 95. For example, although not shown in FIG. 20, an instrument utilizing shape-sensing fiber can provide shape data that the localization module 95 can use to determine the location and shape of the instrument.
The localization module 95 may use the input data 91-94 in combination(s). In some cases, such a combination may use a probabilistic approach where the localization module 95 assigns a confidence weight to the location determined from each of the input data 91-94. Thus, where the EM data may not be reliable (as may be the case where there is EM interference) the confidence of the location determined by the EM data 93 can be decrease and the localization module 95 may rely more heavily on the vision data 92 and/or the robotic command and kinematics data 94.
As discussed above, the robotic systems discussed herein may be designed to incorporate a combination of one or more of the technologies above. The robotic system's computer-based control system, based in the tower, bed and/or cart, may store computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, or the like, that, upon execution, cause the system to receive and analyze sensor data and user commands, generate control signals throughout the system, and display the navigational and localization data, such as the position of the instrument within the global coordinate system, anatomical map, etc.
2. Sheaths for Wristed Instruments.
In electrically-active, wristed instruments, it is typical for only the end effector (or portions thereof) that interact with patient tissue to be conductive. For instruments that are used under higher loads, the wristed components tend to be metal. To provide insulation for such instruments, an insulator in the form of an elastomeric sheath can be provided around the conductive wristed components.
There are multiple challenges to using such elastomeric sheaths. First, the elastomeric sheath should be resistant to both high temperatures (e.g., such as from proximity to arcs or steam from desiccated/burning tissue) and tearing (e.g., such as from impacts or abrasions with other instruments, cannulas and movement from the instrument itself). In addition to tearing, the insulation can be compromised if the sheath slips off the wrist during surgery. Approaches to retain sheath-like insulation tend to skew towards a tight fit, which can make installation difficult, and potentially dangerous, as the sheath is being installed in a motion that loads the hands towards the tip of the blades. Removing the sheath may also be challenging, particularly after the sheath has been coated in fats and fluids.
The present application describes multi-wristed instruments that provide improved shielding to alleviate the challenges faced above. In particular, the shielding is in the form of an elastomeric sheath having a novel design that provides greater heat and tear resistance, and that is both easier to install and remove from the instrument.
Aspects of this disclosure relate to improved shielding for wristed instruments. As shown in FIGS. 21A-B, a wristed instrument 220 can include a shaft 221, an end effector 224, and a wrist joint 222. The instrument 220 may benefit from the inclusion of a sheath (not illustrated) formed over at least a portion of the wrist joint 222. The sheath may shield at least a portion of the wrist of the instrument 220 from the environment, such as within a patient's body. The sheath may be formed of a flexible material, an elastomeric material, an electrically insulating material, etc.
In some aspects, the instrument 220 can be a monopolar instrument which may apply a current through patient tissue to a grounding pad. Desirably, the current passes through the end effector 224 (e.g., a pair of shears). In this implementation, the sheath may electrically insulate the wrist from the patient, thereby preventing current from flowing to/from the patient via the wrist joint 222. The sheath may also substantially seal the wrist joint 222 such that fluids or other foreign materials can be prevented from penetrating into the moving parts of the wrist joint 222 and/or into the shaft 221.
The instrument 220 can be used in manual or robotic procedures. The procedures can include laparoscopy, endoscopy, (e.g., bronchoscopy, ureteroscopy, gastroscopy), or other surgeries, etc. in one implementation, the instrument 220 can be controlled by a robotic arm 200. The robotic arm 200 can be a part of a patient platform or cart as shown in FIGS. 1-20 above. The robotic arm 200 can include a base 205. The base 205 can be mountable and detachable from a patient platform or cart. The robotic arm 200 can comprise a plurality of articulable joints 210. In one implementation, the articulable joints 210 can include seven joint segments. The articulable joints 210 can include motors or other actuators for positioning the robotic arm 200 and the instrument 220.
The robotic arm 200 can include an instrument driver 215. The instrument driver 215 can be similar to the instrument driver 75 described above. The instrument driver 215 can be located at a distal end of the robotic arm 200. The instrument driver 215 can include a mount for receiving the instrument 220. The instrument 220 can be movable (e.g., in an axial direction) with respect to the instrument driver 215. The instrument driver 215 can include one or more drive inputs anchored to respective tendons, such as pull wires. Torque from the drive inputs can be transmitted down the shaft 221 using the pull wires. The instrument driver 215 can transfer tension through the tendons to actuate the end effector 224 and/or the wrist joint 222.
The shaft 221 can be generally straight and/or cylindrical rod. The shaft 221 can be received within the instrument driver 215. The end effector 224 of the instrument 220 can be any type of surgical end effector. In one example, the end effector 224 can comprise a pair of gripping or cutting arms. The end effector 224 can be articulable with respect to the shaft 221. The wrist joint 222 can facilitate the articulation of the end effector 224. FIG. 21A shows the end effector 224 generally aligned with the shaft 221. FIG. 21B shows the end effector 224 articulated with respect to the shaft 221 about the wrist joint 222. The articulation of the end effector 224 can be controlled by the one or more pull wires within the shaft 221 and controlled by the instrument driver 215. Other control mechanisms for articulation of wrist joint 222 are also contemplated herein.
FIG. 22 illustrates an example instrument 320 including a shaft 321, a wrist joint 322, and an end effector 324. The wrist joint 322 can connect the shaft 321 with the end effector 324. The wrist joint 322 can be articulable with respect to the shaft 321. In some implementations, the wrist joint 322 can include a first clevis joint 322a, an intermediate clevis joint 322b, and a second clevis joint 322c. In other implementations, the wrist joint 322 can include a proximal clevis and a distal clevis. The second clevis joint 322c can be articulable with respect to the first clevis joint 322a. The first clevis joint 322a can be connected with the shaft 321. The second clevis joint 322c can be connected with the end effector 324. The intermediate clevis joint 322b can include one or more pins or other structures for allowing the second clevis joint 322c to rotate or roll with respect to the first clevis joint 322a and shaft 321. The first clevis joint 322a and/or the intermediate clevis joint 322b can include one or more apertures for receiving one or more pull wires that connect with the second clevis joint 322c to control articulation thereof. The wrist joint 322 is further described in U.S. patent application Ser. No. 16/711,052, filed on Dec. 11, 2019.
The end effector 324 can be any type of surgical end effector. As illustrated, the end effector 324 can be shears or grippers that include first and second prongs 324a, 324b. The first and second prongs, 324a, 324b can be connected together at a pivot 324c. The first and second prongs 324a, 324b can be moveable with respect to each other for cutting tissue. The articulation and movement of the first and second prongs 324a, 324b can be controlled by one or more pull wires extending through the shaft 321 and the wrist joint 322. In certain implementations, the end effector 324 can be articulable with respect to the wrist joint 322 about the pivot 324c. 
As noted above, the instrument 320 can be an electrically-active instrument, such as a monopolar instrument. Desirably, the wrist joint 322 and a portion of the shaft 321 can be insulated by a sheath 340. The sheath 340 can include a first (proximal) end 341 and a second (distal) end 343. The first and second ends 341, 343 can each include openings. The sheath 340 can include a generally cylindrical or tubular portion 342. The opening of the first end 341 can be into the tubular portion 342. The sheath 340 can include a conical portion 344. The conical portion 344 can be truncated.
The sheath 340 can be assembled over the instrument 320, e.g., by slipping a portion of the instrument 320 through the sheath 340 (e.g., through the opening of the first end 341). The tubular portion 342 can fit over the wrist joint 322. The opening of the second end 343 can transition from the conical portion 344. The conical portion 344 can fit over a portion of the wrist joint 322 and/or a portion of the end effector 324 such as a base of the prongs 324a, 324b, and/or the pivot or pin 324c. The placement of the insulating sheath 340 over the wrist joint 322 and partially over the end effector 324 is illustrated in FIG. 22 in dash lines.
The sheath 340 can comprise an elastic material to allow assembly with the wrist joint 322. To retain the sheath 340 in place on the wrist joint 322, the sheath can have a relatively tight fit. The wrist joint 322 can also include a ring such as a circumferential groove 326 and/or circumferential ridge 327. The ring can interact with a corresponding structure (e.g., circumferential rib or groove, respectively) on the inner side of the tubular portion 342. By interlocking the corresponding rib/groove structures, the sheath 340 can be more securely retained on the wrist joint 322.
FIG. 23A shows the sheath 340 installed on the instrument 320. The tubular portion 342 can be generally assembled over the wrist joint 322. The conical portion 344 can be generally assembled over the base of the end effector 324. The prongs of the end effector 324 can be exposed through the opening of the second end 343. The first end 341 can at least partially overlap the shaft 321 of the instrument 320. Accordingly, the sheath 340 can insulate all or a portion of the wrist joint 422 against electrical arcing or unintended current paths to patient tissue.
As shown in FIG. 23B, the material of the insulating sheath 340 is flexible enough to allow articulation of the wrist joint 322. FIG. 23B shows the end effector 324 aligned along an axis 332 and the shaft 321 aligned along an axis 331. The wrist joint 322 is articulated such that the axis 332 of the end effector 324 is at an angle 330 with respect to the axis 331 of the shaft 321. The angle 330 can be between about 0° and about 90° or more.
FIG. 24 shows another implementation of an instrument 420. The instrument 420 can include a shaft 421, a wrist joint 422 and/or an end effector 424. A sheath 440 can be assembled on the wrist joint 422. The sheath 440 can include a first end 441, tubular portion 442, conical portion 444 and/or a second end 443. The end effector 424 is aligned along an axis 432 and the shaft 421 is aligned along an axis 431. The end effector 424 is pivotal about a pivot pin of the wrist joint 422. The pivot pin can be the same pivot location for the prongs of the end effector 424. The end effector 424 can be articulated an angle 430. The angle 430 can be between about 0° and about 90° or more.
For wristed, monopolar instruments, such as the instruments 220, 320, 420, only the end effector, or specified portions thereof are expected to interact with patient tissue and should therefore be formed of conductive (e.g., metallic) materials. Current can pass from the conductive end effector to patient tissue. In instrument types used under higher loads, wrist components also tend to comprise metal. Accordingly, the wrist components can be insulated with a sheath. The sheaths can be formed of an elastomer to accommodate the range of motions required by wristed instruments. The surgical environment also requires the sheath be resistant to high temperatures due to the proximity to electrical arcs and/or steam from desiccated/burning tissue. Tears can also form due to impacts or abrasions with other instruments, cannula, and pinching from the wrist components. While the sheath can be replaceable, close monitoring of the sheath is not always practicable. For example, in laparoscopic surgery the wrist joint and sheath are not always within the field of view of the camera. The insulative properties of the sheath can be compromised due to the tears and/or if the sheath slips off the wrist during surgery.
Approaches to retain sheath-like insulation on wrists include a tight fit, which can make installation of the sheath difficult and potentially dangerous. For example, the sheath can be installed in a motion that loads the hands towards the tip of the end effector (e.g., blades). Removing the sheath may also be difficult, particularly after the sheath has been coated in fats and fluids from surgery. Blades may be used to remove the sheath, but this can damage the wrist structures on an instrument wrist that should have multiple uses. Accordingly, a need exists for an improved sheath for a wristed instrument.
Accordingly, one aspect of this disclosure is an insulating sheath that includes an inner support structure 548 as shown in FIG. 25. The support structure 548 can be a braided structure. The support structure 548 can include a plurality of interwoven strands 551, 552 that form a generally tubular shape. The support structure 548 can include a generally tubular portion 562. The support structure 548 can include a generally conical structure 564. In certain alternatives, only the generally tubular portion 562 is included. In certain alternatives, the support structure can include a fabric structure.
The support structure 548 can include a first set of strands 551 aligned along a first direction and a second group of strands 552 aligned along a second direction. The strands 551 and/or 552 can be formed of a polymer material, metal, nylon, polypropylene, natural fibers or other material. The strands 551 and/or 552 can be monofilament or multifilament strands. The profile or cross-sectional profile of the strands 551 and/or 552 can be circular, oval, or generally flat. The strands 551 can be interwoven under and over the strands 552 in a braided or woven pattern 550. At either end of the support structure 548, the strands 551, 552 can either be cut off or interwoven back into the support structure 548.
Certain nonlimiting options for the braid pattern 550 are shown in FIGS. 26A-26C. A braid pattern 550a can be a 1:1 braid pattern as shown in FIG. 26A. Strands 551a can extend in a first direction and interweave strands 552a extending in a second direction. A braid pattern 550b can be a 2:1 braid pattern as shown in FIG. 26B. Strands 551b can extend in a first direction and interweave strands 552b extending in a second direction two at a time. Adjacent strands 551b can be offset from each other in the interweaving of the strands 552b. A braid pattern 550c can be a 2:2 braid pattern as shown in FIG. 26C. Two strands 551c can extend in a first direction and interweave two strands 552c extending in a second direction. Adjacent pairs of strands 551c can be offset from each other in the interweaving of the strands 552b. 
FIG. 27A-29 show an insulation sheath 640. The insulation sheath 640 can include a first end 641, a second end 643, a tubular portion 642, and/or a conical portion 644. The insulation sheath 640 can include a braided structure 648 fully or partially covered in a high temperature resistant and flexible material 649. The material 649 can comprise silicone. Alternatively, another high temperature resistant and flexible materiel can be used.
The braided structure 648 can be fully embedded within the material 649 of the sheath 640. A tubular portion 662 of the braided structure can be located within the tubular portion 642 of the sheath 640. A conical structure 664 of the braided structure 648 can be within the conical portion 644 of the sheath 640. Desirably, the braided structure 648 can extend from the first end 641 to the second end 641. The strands of the braided structure 648 can be fully embedded or protrude from the material 649 at the first and/or second ends 641, 643. In other implementations (not shown), the braided structure 648 can extend only within the generally tubular portion 642. For example, the braided structure 648 can extend from the first end 641 to the intersection between the tubular portion 642 and the conical portion 644.
The first end 641 of the sheath 640 can include a diameter D1. The diameter D1 can be uniform throughout the tubular portion 642. The diameter D1 can be between about 5 mm and about 7 mm. The second end 643 can include a diameter D2. The diameter D2 can be adjacent a distal surface 643a of the conical portion 644. The diameter D2 can be within an opening 643b of the conical portion 644. The diameter D2 can be between about 3 mm and about 4 mm. The diameter D2 can be less than diameter D1. The diameter D3 can be located at an intersection of the conical portion 644 with the tubular portion 642. The diameter D3 can be equivalent to the diameter D1. Alternatively, the generally tubular portion 642 can include multiple different inner diameters (e.g., to match closely geometry of a wrist joint). The tubular portion can have a length L1. The length L1 can be between about 25 mm and about 60 mm. The conical portion 644 can have a length L2. The length L2 can be between about 4 mm and about 5 mm. The length L1 can be greater than the length L2.
An inner surface of the conical portion 644 can include a circumferential ring 650. The ring 650 can be a circumferential ridge or groove. The ring 650, or valley, can be sized to match or engage with a corresponding groove or ridge within the wrist joint of the instrument for which the insulation sheath 640 is designed. The ring 650 can be located a distance L3 from the first end 641. L3 can be less than L1 and/or less than L2. Alternatively, the ring 650 can be located anywhere within the tubular portion 642. The sheath 640 can include multiple rings 650.
3. Implementing Systems and Terminology.
It should be noted that the terms “couple,” “coupling,” “coupled” or other variations of the word couple as used herein may indicate either an indirect connection or a direct connection. For example, if a first component is “coupled” to a second component, the first component may be either indirectly connected to the second component via another component or directly connected to the second component.
As used herein, the term “plurality” denotes two or more. For example, a plurality of components indicates two or more components. The term “determining” encompasses a wide variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing and the like.
The phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on.”
The previous description of the disclosed implementations is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of the invention. For example, it will be appreciated that one of ordinary skill in the art will be able to employ a number corresponding alternative and equivalent structural details, such as equivalent ways of fastening, mounting, coupling, or engaging tool components, equivalent mechanisms for producing particular actuation motions, and equivalent mechanisms for delivering electrical energy. Thus, the present invention is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

## Claims

1. A robotic surgical system comprising:
a robotic arm including an instrument driver, the instrument driver including one or more drive inputs coupled to respective pull wires; and
a conductive instrument comprising:
an elongated shaft coupled with the instrument driver;
an end effector;
a wrist joint connecting the elongate shaft with the end effector, the pull wires coupled with the wrist joint and configured to articulate the end effector with respect to the elongate shaft; and
a sheath insulating the wrist joint and including a tubular portion comprising:
an insulative material including a conical portion configured to cover a base of the end effector; and
an internal support structure comprising a braided structure formed of interwoven strands and fully embedded within the insulative material and extending into the conical portion,


wherein the end effector and the wrist joint each comprise a conductive material.

2. The system of claim 1, wherein the conductive instrument is a monopolar instrument.

3. The system of claim 1, wherein the conductive instrument is a laparoscopic instrument.

4. The system of claim 1, wherein the insulative material is a silicone material.

5. The system of claim 4, wherein the internal support structure is encased within the silicone material.

6. The system of claim 1, wherein a distal end of the sheath has an opening with a diameter smaller than an opening of a proximal end of the sheath.

7. The system of claim 6, wherein the proximal end of the sheath extends at least partially over the elongate shaft.

8. The system of claim 1, wherein the tubular portion includes an internal ring and the wrist joint includes a corresponding ring that retains the sheath in position on the wrist joint.

9. The system of claim 1, wherein the interwoven strands of the braided structure comprise monofilament.

10. The system of claim 1, wherein the interwoven strands of the braided structure are multifilament.

11. The system of claim 1, wherein the interwoven strands of the braided structure are circular in cross section.

12. The system of claim 1, wherein the interwoven strands of the braided structure are generally rectangular in cross section.

13. The system of claim 1, wherein the interwoven strands of the braided structure comprise polypropylene.

14. The system of claim 1, wherein the interwoven strands of the braided structure comprise nylon.

15. The system of claim 1, wherein the interwoven strands of the braided structure includes a 1:1 braid pattern.

16. The system of claim 1, wherein a diameter of the tubular portion varies from a first end to a second end of the tubular portion and is configured to match contours of the wrist joint.

17. The system of claim 1, wherein the interwoven strands of the braided structure includes a 2:1 braid pattern.

18. The system of claim 1, wherein the interwoven strands of the braided structure includes a 2:2 braid pattern.