Patent Publication Number: US-2022234216-A1

Title: Quick release coupler

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 16/467,756 filed Jun. 7, 2019; that in turn claims priority benefit of U.S. Provisional Application Ser. No. 62/433,373 filed Dec. 13, 2016; the contents of the aforementioned are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention in general relates to the field of mechanical couplers for connecting tools to a machine, and more specifically to a quick-release mechanical coupler for connecting tools to a surgical robot. 
     BACKGROUND 
     Couplers, or couplings, are commonly used to connect tools to machines. In some instances, couplers are configured with a quick release mechanism to rapidly release and connect tools to a machine, and are referred to as a quick-release coupler. A quick-release coupler is especially useful in situations where several tools are needed to connect to a single machine to perform a given task, or where the time for completing a given task is a matter of interest. These situations are often encountered in the field of surgical robotics where one or more tools need to be connected to the end of a robotic arm. 
     Due to the strict safety and accuracy requirements to perform robotic surgery, any coupler used during the procedure must meet several requirements. For one, the tools need to rigidly connect to the surgical robot such that there is minimal deflection between the tool and the robot. Often, a calibration step is performed prior to executing the procedure to identify the position and orientation of the tool tip, or working portion of the tool, in a coordinate frame of the robot. If the tool deflects after this calibration step, then the accuracy of the procedure is compromised. Second, the coupler connection needs to withstand the forces generated between the tool and the workpiece as well as any vibrational motion the robot may generate during the procedure. Like before, maintaining the rigidity between the tool and the robot is critical. 
     In addition, a surgical setting has sterility requirements where all of the components that directly interact with a patient must be sterile. Some quick-release couplers contain several small moving parts to firmly grasp the tool, which may be difficult to fully sterilize. A sterile drape may cover and shield the quick-release coupler from the patient, however the drape may inadvertently interact with any of the levers on the coupler used to connect and release the tool with the robotic arm. 
     Finally, the quick-release coupler has to account for the manufacturing tolerances between the coupler and the tool connection interface. More specifically, each tool has an attachment member that connects with the coupler. The attachment member for each tool may have a slightly different size, shape, or geometry due to the designated manufacturing tolerance (e.g., +/−0.5 mm). Therefore, the coupler design should accommodate for the minor variances in shape, size, or geometry from tool to tool due to the manufacturing tolerances, such that the rigidity between the robot and the different tools is maintained. 
     Thus, there exists a need for a quick-release coupler capable of connecting several types of tools to a robot and to maintain the rigidity between the tool and the robot during a surgical procedure. 
     SUMMARY 
     A coupling device is provided herein. The coupling device includes a body having a mounting member and a receiving member. The mounting member is attached to the body with a first set of fastening elements. The receiving member is attached to an opposing side of the body with a second set of fastening elements. The mounting member is adapted to connect to a portion of a machine and the receiving member is adapted to removably join and suspend one or more different tools. The portion of the machine may include a distal link of a manipulator arm of a robot. The receiving member further includes a conduit and a support where the conduit provides a link for a locking pin to intercept a portion of the tool. The support may be a sliding joint that is tapered with where an opening of the sliding joint has a larger cross-section than a stopper portion of the joint. The stopper portion provides an abutment surface for a corresponding mating feature of the tool to push against to rigidly secure the tool to the coupler. The corresponding mating feature may be a wedged attachment that slides onto the receiving member. The wedged attachment further includes an interaction counterbore bored through a top side of a portion of the wedged attachment. A wall in the interaction counterbore interacts with the locking pin such that when the locking pin is engaged the locking pin imposes a lateral force on the wall to rigidly secure the tool against the support of the coupler. 
     The body of the coupling device may further include a housing, a locking pin, a lever, a lid, one or more pawls, one or more pawl springs, a pawl release, a release button, a release lever, a biasing spring, one or more translation pins, a set screw, and fastening elements. The housing has a housing counterbore to hold the locking pin therein and a slot extending laterally from the housing counterbore through a portion of the housing. The lever fits within the slot and has an attachment end that inserts into a corresponding aperture in a shaft portion of the locking pin. The lever is used to rotate the locking pin within the counterbore to engage the tool. 
     A process of using the coupling device is provided including attaching a tool to the coupling device. 
     A system is also provided including a robot with a manipulator arm joined to the coupling device for removably joining a set of tools. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is further detailed with respect to the following drawings that are intended to show certain aspects of the present of invention, but should not be construed as a limit on the practice of the invention, wherein: 
         FIG. 1  depicts a robotic system having a coupler and a tool attached thereto in accordance with embodiments of the invention; 
         FIGS. 2A and 2B  depict a coupler for connecting a tool to a machine, where  FIG. 2A  shows the coupler in an assembled state, and  FIG. 2B  shows an exploded view thereof in accordance with embodiments of the invention; 
         FIGS. 3A-3C  depict a mounting member of the coupler of  FIGS. 2A and 2B  that connects with a machine, where  FIG. 3A  is a perspective view of the mounting member,  FIG. 3B  is a top view thereof, and  FIG. 3C  is a side view thereof in accordance with embodiments of the invention; 
         FIGS. 4A-4D  depict a receiving member of the coupler of  FIGS. 2A and 2B  that receives a tool, where  FIG. 4A  is a perspective top view of the receiving member,  FIG. 4B  is a front view thereof,  FIG. 4C  is a perspective bottom view thereof, and  FIG. 4D  is a bottom view thereof; 
         FIGS. 5A-5D  depict an attachment region and a tool for attaching with the receiving member of  FIGS. 4A-4D , where  FIG. 5A  is a perspective view of the attachment region,  FIG. 5B  is a top view thereof,  FIG. 5C  is a front cross-sectional view thereof, and  FIG. 5D  is the attachment region assembled with a tool, in accordance with embodiments of the invention; 
         FIG. 6  is an exploded view of the body of the coupler of  FIGS. 2A and 2B  in accordance with embodiments of the invention; 
         FIGS. 7A-7E  depict detailed perspective views of the locking pin shown in  FIG. 6  that secures a tool to the coupler, where  FIG. 7A  is a perspective view of the locking pin,  FIG. 7B  is first rotational position thereof,  FIG. 7C  is a second rotational position thereof,  FIG. 7D  is a top view thereof, and  FIG. 7E  is a cross-section view thereof, in accordance with embodiments of the invention; 
         FIGS. 8A-8D  depict detailed perspective views of the lid shown in  FIG. 6  of the coupler that facilitates a translational motion of the locking pin, where  FIG. 8A  is a top view of the lid,  FIG. 8B  is side view thereof,  FIG. 8C  is bottom view thereof, and  FIG. 8D  is a cross-sectional view thereof in accordance with embodiments of the invention; 
         FIG. 9  depicts a detailed perspective view of the translational pin shown in  FIG. 6  that interacts with the lid in accordance with embodiments of the invention; 
         FIG. 10  depicts a detailed perspective view of the pawl release shown in  FIG. 6  that facilitates the release of a pawl from the locking pin in accordance with embodiments of the invention; 
         FIG. 11  depicts a detailed perspective view of the pawl shown in  FIG. 6  that engages the locking pin in accordance with embodiments of the invention; 
         FIG. 12  depicts a detailed perspective view of the pawl spring shown in  FIG. 6  that interacts with the pawl in accordance with embodiments of the invention; 
         FIGS. 13A-13B  are top down views of the pawl release mechanism of  FIG. 10 , where  FIG. 13A  shows the pawl release mechanism in an engaged position and  FIG. 13B  is in a disengaged position in accordance with embodiments of the invention; 
         FIGS. 14A-14B  depict a bottom surface of the coupler body for assembling the pawl release mechanism, where  FIG. 14A  is the bottom surface having no pawl release components and  FIG. 14B  is the assembled pawls and springs with the body in accordance with embodiments of the invention; and 
         FIGS. 15A-15B  depict a cross-sectional view of the assembled coupler of  FIG. 2A , where  FIG. 15A  is the coupler in a disengaged position and  FIG. 15B  is the coupler in an engaged position in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention has utility as a mechanical coupler to quickly and rigidly connect a tool to a machine. The mechanical coupler is especially advantageous in a surgical setting where time is of the essence and where a single machine operates different tools at different time points to perform a single procedure. Further, the mechanical coupler is capable of connecting tools having small geometric deviations in their attachment regions, while still providing a rigid connection between the machine and the tool. 
     The following description of the various embodiments of the invention is not intended to limit the invention to these specific embodiments, but rather to enable any person skilled in the art to make and use the invention through exemplary aspects thereof. In particular, the following description provides examples related to a coupler for connecting a tool to a surgical robot; however, it should be appreciated that the embodiments described herein are readily adapted for use in a myriad of applications where it is desirous to connect two or more objects. 
     It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range, but also intermediate values of the range as explicitly included within the range and varying by the last significant figure of the range. By way of example, a recited range from 1 to 4 is intended to include 1-2, 1-3, 2-3, 2-4, 3-4, and 1-4. 
     Referring now to the figures,  FIG. 1  illustrates a robotic system  100  including a robot base  106 , a manipulator arm  108  mounted to the base  106  having a distal link  110 , a mechanical coupler  200  connected to the distal link  110 , and a tool  300  attached to the coupler  200 .  FIG. 1  is provided for context as a potential application for the use of the mechanical coupler  200  described herein. In particular, the robotic system  100  may perform orthopedic procedures such as total knee arthroplasty (TKA) and total hip arthroplasty (THA) where several different tools are used by the robotic system during the course of a single procedure. One specific example is the reaming of the acetabular cup during THA where several reamers are exchanged on the robotic arm  108  to prepare the acetabulum to receive a prosthetic cup. Examples of such robotic systems are described in U.S. Pat. Nos. 5,086,401, 6,102,850 and 7,206,626, which are incorporated by reference herein in their entirety. 
     With reference to  FIGS. 2A and 2B , the mechanical coupler  200  is shown, where  FIG. 2A  is a perspective view of the coupler  200  and  FIG. 2B  is an exploded view thereof. The coupler  200  includes a body  202  having a mounting member  204  and a receiving member  206 . The mounting member  204  is assembled to the body  202  with a first set of fastening elements  212 , while the receiving member  206  is assembled to an opposing side of the body  202  with a second set of fastening elements  214 . The fastening elements ( 212 ,  214 ) shown here are screws, however other fastening elements may be used such as clamps, rivets, screw caps, and equivalents thereof. 
     With reference to  FIGS. 3A-3C , the mounting member  204  is shown in detail, where  FIG. 3A  is a perspective view of the mounting member  204 ,  FIG. 3B  is a top view thereof, and  FIG. 3C  is a side view thereof. The mounting member  204  is adapted to connect to a portion of a machine, such as the distal link  110  of the manipulator arm  108 . In a particular embodiment, the mounting member  204  has an annular base  220  and a cylindrical top  216  with a hyperboloid neck  222  therebetween. The top  216  and neck  222  having diameters less than the annular base  220  for inserting inside a locking mechanism (not shown) associated with the machine. One or more alignment slots  218  may be formed around the edge of the cylindrical top  216  to mate with one or more corresponding projections associated with the locking mechanism of the machine. The alignment slots  218  ensure the coupler  200  may be repeatedly connected to the machine in a desired orientation. The neck  222  may be securely grasped by a set of retractable ball bearings associated with the machine locking mechanism to rigidly fix the coupler  200  to the machine. In addition, the annular base  220  may further include a set of screw holes  226  to receive the set of fastening elements  212  to assemble the mounting member  204  with the body  202 . 
     In other embodiments, the mounting member  204  may have alternative mechanisms known in the art for connecting the coupler  200  to the machine. For example, the mounting member  204  may have a shaft with threads that screw into a portion of the machine, a clamping mechanism, or equivalents thereof to maintain a rigid relationship between the machine and the mounting member  204 . It is further contemplated that the coupler  200  may be a permanently assembled or manufactured as part of the machine (or other object). In this case, the coupler  200  may not include a mounting member  204 , or the mounting member  204  may be permanently assembled to the machine. 
     With reference to  FIGS. 4A-4D  the receiving member  206  of the body  202  is shown in detail, where  FIG. 4A  is a top perspective view of the receiving member  206 ,  FIG. 4B  is front view thereof,  FIG. 4C  is a bottom perspective view thereof, and  FIG. 4D  is a bottom view thereof. The receiving member  206  is adapted to removably join and suspend the tool  300  to the coupler  200 . In a particular embodiment, the receiving member  206  has a conduit  228  and a support  230 . The conduit  228  provides a link for a locking pin  236  (shown in  FIG. 6 ) to intercept a portion of the tool  300  as described below. The support  230  is adapted to mate with the tool  300 . In a specific embodiment, the support  230  is a sliding joint (e.g., “stopped” sliding dovetail joint) that mates with a corresponding mating feature on the tool  300 . The sliding joint may be tapered where an opening  231  of the joint has a larger cross-section than the “stopped” portion  232  of the joint. The “stopped” portion  232  may provide an abutment surface for the corresponding mating feature on the tool to push against to rigidly secure the tool  300  to the coupler  200  as further described below. It should be appreciated, that the “stopped” portion  232  refers to any portion of the joint that extends away from the opening  231  where the corresponding mating feature on the tool  300  may push against any region of the “stopped” portion  232  (e.g., the side walls of the dovetail joint may act as the abutment surface, where the mating feature may push against the side walls of the dovetail joint without contacting a region of the “stopped” portion  232  furthest from the opening  231 ). In other embodiments, the support  230  may be a simple lip or slot that the tool  300  can mate with or slide onto for removably joining and suspending the tool  300 . 
     With reference to  FIGS. 5A-5D , a tool  300  having a wedged attachment region  302  is shown in detail, where  FIG. 5A  is a perspective view of the attachment region  302 ,  FIG. 5B  is a top view of thereof,  FIG. 5C  is cross-sectional view thereof along line  316  of  FIG. 5B , and  FIG. 5D  depicts the tool  300  having the attachment region  302 . The attachment region  302  is adapted to mate and/or slide onto the receiving member  206 . In a specific embodiment the attachment region  302  has a top surface  303 , a bottom surface  305 , and wedged angled features  308  therebetween that slide onto the support  230  (i.e., the dovetail joint). The attachment region  302  further includes a locking pin interaction feature  304 . In a particular embodiment, the interaction feature  304  is in the form of a counterbore bored through a portion of the attachment region  302  leaving a counterbore interaction wall  307  and an interaction surface face  306  situated between the top surface  303  and the bottom surface  305 . A locking pin  236  (shown in  FIG. 6 ) engages the interaction feature  304  as further described below. The wedge-shaped attachment region  302  further includes fastening holes  310  for fastening elements to attach the attachment region  302  with the tool  300 . In a specific embodiment, the tool  300  as shown in  FIG. 5D  is a powered cutter having a cutter tip  312  driven by a motor  314 . However, it should be appreciated that the attachment region  302  may be assembled with any type of tool including but not limited to a reamer, a burr, an electrocautery device, a probe, an endoscope, a drill, a prosthetic implant, or any other instrument that interacts with a user, a workpiece, a subject, or the environment. In another embodiment, the coupler  200  is adapted to removably couple with a workpiece rather than a tool. The workpiece may include an attachment region that interacts with the receiving member  206  of the coupler  200 . The workpiece may be, for example, a patient&#39;s anatomy (e.g., bone), wood, metals, polymers, or other objects that will undergo some type of processing, modification, or alteration. 
     With reference to  FIG. 6 , the body  202  of the coupler  200  is shown in an exploded view. The body  202  is configured to permit a user to engage and disengage a locking pin  236  with the interaction feature  304 . When the user engages the locking pin  236 , a portion of the locking pin  236  imposes a lateral force on the interaction feature  304  to rigidly secure the tool  300  against the support  230  of the coupler  200 . In particular, the locking pin  236  imposes a lateral force on the interaction wall  307  to securely “wedge” and draw the attachment region  302  into the support  230  (i.e., wedged sliding joint). In a specific embodiment, the body  202  includes a housing  234 , the locking pin  236 , a lever  237 , a lid  238 , one or more pawls  240 , one or more pawl springs  242 , a pawl release  244 , a release button  246 , a release lever  248 , a biasing spring  250 , one or more translation pins  252 , a set screw  253 , and fastening elements  254 . The housing  234  has a counterbore  256  to hold the locking pin  236  therein and a slot  258  extending laterally from the counterbore  256  through a portion of the housing  234 . The lever  237  fits within the slot  258  and has an attachment end  262  that inserts into a corresponding aperture  260  in the shaft of the locking pin  236 . The lever  237  allows the user to rotate the locking pin  236  within the counterbore  256 . The lid  238  has features that cause the locking pin  236  to translate within the counterbore  256  as the locking pin  236  rotates to engage the tool  300 . 
     With reference to  FIGS. 7A-7E , the locking pin  236  is shown in detail, where  FIG. 7A  is a perspective view of the locking pin  236 ,  FIG. 7B  shows the locking pin  236  in a disengaged position,  FIG. 7C  shows the locking pin in an engaged position,  FIG. 7D  is a top view thereof, and  FIG. 7E  is a cross-section thereof along line  271  of  FIG. 7D . In a particular embodiment, the locking pin  236  is a shaft  263  having a pin head  264  at a proximal end of the shaft  263 , an aperture  260  for receiving the lever  237 , a plurality of teeth  266  radially positioned on an outer surface of the shaft  263 , and an eccentric cam  268  at a distal end of the shaft  236 . The eccentric cam  268  is offset from the center axis  270  of the shaft  263  which applies a lateral force against the wall  307  of the attachment region  302  when the locking pin  236  is engaged. This can be viewed between  FIGS. 7B and 7C , where  FIG. 7B  illustrates the locking pin  236  rotated in a disengaged position and  FIG. 7C  illustrates the locking pin  236  rotated in an engaged position. The plurality of teeth  266  engage with one or more pawls  240  to incrementally lock the rotational position of the locking pin  236  as the locking pin  236  is rotated. The plurality of teeth  266  may be manufactured as a part of the locking pin  236 , as a sprocket, or a removable set of teeth may be attached thereto. The locking pin  236  further include translation pins  252  projecting from the pin head  264  and a channel  274  where the set screw  253  (as shown in  FIG. 6 ) is inserted and screwed against the attachment end  262  of the lever  237  to secure the lever  237  to the locking pin  236 . 
     With reference to  FIGS. 8A-8D , the lid  238  is shown in detail, where  FIG. 8A  is a top view of the lid  238 ,  FIG. 8B  is a side view thereof,  FIG. 8C  is a bottom view thereof, and  FIG. 8D  is a cross-section thereof through line  280  of  FIG. 8C . The lid  238  is configured to cause the locking pin  236  to translate as the locking pin  236  is rotated. In a particular embodiment, the lid  238  has a top portion  276 , and a bottom portion  277 . The bottom portion  277  has a cylindrical shape with two grooves  279 . The grooves  279  interact with the translation pins  252  that project from the locking pin  236 . In particular, the translation pins  252  (as shown in  FIG. 9 ) have a dome portion  283  that fit into the grooves  279  and a press-fit portion  284  that attach with the pin head  264  of the locking pin  236 . The inside of each groove  279  has an undulating surface as seen in  FIG. 8D . One side of the groove  281  has a surface lower than the opposite side  282  by a distance ‘D’. As the locking pin  236  is rotated, the undulating surface makes the locking pin  236  translate. 
     With reference to  FIGS. 10-13B , a mechanism for incrementally locking a rotational position of the locking pin  236  and releasing the lock is shown in detail. The pawl release mechanism  241  is configured to disengage the pawls from the plurality of teeth  266  on the locking pin  236 . In particular embodiment, the pawl release  244  is of a semi-annular shape having one or more pawl engagement features  284 , a conduit  283 , and a release lever attachment point  285 . The pawl engagement feature(s)  284  may be an angled elliptical opening that receives a portion of the pawl  240 . For example, as shown in  FIG. 11 , the one or more pawls  240  have an engaging element  285  for engaging the plurality of teeth  266  and a pin  286  that fits within the pawl engagement feature  284 . One or more pawl spring  242 , as shown in  FIG. 12 , is configured about each of the pawls  240  such that the pawls  240  can engage each of the teeth  266  as the locking pin  236  is rotated. To release the pawl(s)  240  from the teeth  266 , a user pushes on a release button  246  connected to a release lever  248  that is connected to the pawl release  244 . Pushing the release button  246  rotates the pawl release  244  causing each of the pawls to rotate away from the teeth  266 . The pawls rotate because the pin  286  moves within the pawl engagement feature  284  (e.g., an angled elliptical opening) angled away from the teeth  266 .  FIG. 13A  depicts the pawl(s)  240  in the engaged position, and  FIG. 13B  depicts the pawl(s)  240  in the disengaged position due to the rotation of the pawl release  244 . 
     There are several advantages of having multiple pawls  240 , including the ability to increase the locking resolution of rotation. In a particular inventive embodiment, the spacing of the plurality of teeth  266 , the positioning of the pawls  240  around the teeth  266 , and the number of pawls  240 , is configured such that only one or two pawls  240  are engaged with one or two teeth at any given rotational position. Therefore, the slightest rotation will cause one or two other pawls  240  to engage one or two other teeth  266 . This configuration provides several additional advantages. For one, when manufacturing the attachment region  302  of the tool  300 , the geometry of each attachment region may vary slightly due to manufacturing tolerance. The several locking positions and resolution of locking accommodates for these slight variations for each tool  300  used with the machine. Second, by having several locking positions, the risk of the tool  300  detaching from the coupler  200  is greatly reduced because there are several “stops” before the tool  300  can be fully detached. In addition, with a coupler having only one pawl  240  or one locking position (as opposed to the multiple paws  240  described herein), unintended external forces (e.g., a surgical drape surrounding the coupler, vibrations or motions of the machine or robot, or a user bumping the coupler  200 ), may snag the lever  237  and inadvertently release the tool  300  from the coupler  200 . Therefore, several locking positions also provide several degrees of connection security. 
     With reference to  FIG. 14A , a bottom surface  286  of the body  202  (see  FIG. 6 ) is shown. The bottom surface  286  is adapted to receive and assemble the pawl release mechanism  241 . In a particular embodiment, the bottom surface  286  is manufactured having a pawl release recession  287  to receive the pawl release  244 , a release lever recession  288  to receive the release lever  248 , a release button recession  289  to receive the release button, and a pawl and spring recession  290  to receive and assemble the pawls  240  and pawl springs  242 .  FIG. 14B  shows the pawls  240  and springs  242  assembled with the body  202 . 
     With reference to  FIG. 15A-15B  a cross-section of the assembled coupler  200  is shown.  FIG. 15A  shows the coupler  200  in a disengaged position where the locking pin  236  is fully housed within the body  202  and the conduits ( 228 ,  283 ) of the receiving member  206  and pawl release  244 . In this position, the attachment region  302  of the tool  300  can slide onto the support  230  where the tool  300  is now suspended thereon. To rigidly secure the tool  300  to the coupler  200 , the user rotates the lever  237  causing the locking pin  236  to rotate and translate towards and against the locking pin interaction feature  304  of the attachment region  302  (see  FIGS. 5A-5D ). The locking pin  236  applies a lateral force (the lateral force is aided by the eccentric cam  268  of the locking pin  236 ) against the interaction feature  304  which pulls the tool  300  into the support  230  to rigidly and securely lock the tool  300  to the coupler  200 .  FIG. 15B  shows the coupler  200  in the engaged position where the locking pin  236  extends partially within the support  230  as depicted in the circled region  292 . To release the tool  300  from the coupler  200 , the user presses the release button  246  to disengage the pawls and rotates the lever  237  back to the disengaged position where the biasing spring  250  (see  FIG. 6 ) aids in translating the pin  236  back into the body  202 . The user can then slide the tool  300  off the support  230  and assemble another tool  300  thereto if needed quickly and effectively. 
     In a particular embodiment, with reference back to  FIG. 2A , the body  202  further includes a groove  205  to facilitate the assembly of a sterile drape to the machine. The sterile drape may have a tubular form to encapsulate a portion of the machine (e.g., an arm of a surgical robot) and provide a sterile barrier to the environment. One end of the sterile drape may be configured to slip into the groove  205  of the body  202  to easily assemble that end of the sterile drape to the coupler  200 . The end of the sterile drape may be elastic to conform and hold the end of the sterile drape in the groove  205 . This may alleviate the need to use adhesives to attach the sterile drape to the machine. The use of the groove  205  also ensures the end of the sterile drape remains on the coupler  200  and prevents the drape from sliding off of the coupler  200  and into the workspace. One example of a sterile drape for a surgical robot is described in U.S. patent application Ser. No. 15/744,253 assigned to the assignee of the present application and incorporated by reference herein. 
     Other Embodiments 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the described embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes may be made in the function and arrangement of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.