Patent Publication Number: US-2023141953-A1

Title: System for neuronavigation registration and robotic trajectory guidance, robotic surgery, and related methods and devices

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 16/737,029 filed on Jan. 8, 2020, which is a continuation-in-part of U.S. patent application Ser. No. 16/452,737, filed Jun. 26, 2019, which is a continuation-in-part of U.S. patent application Ser. No. 16/361,863, filed Mar. 22, 2019, the entire contents of each of which are hereby incorporated by reference in their entireties for all purposes. 
    
    
     FIELD 
     The present disclosure relates to medical devices and systems, and more particularly, systems for neuronavigation registration and robotic trajectory guidance, robotic surgery, and related methods and devices. 
     BACKGROUND 
     Position recognition systems for robot assisted surgeries are used to determine the position of and track a particular object in 3-dimensions (3D). In robot assisted surgeries, for example, certain objects, such as surgical instruments, need to be tracked with a high degree of precision as the instrument is being positioned and moved by a robot or by a physician, for example. 
     Position recognition systems may use passive and/or active sensors or markers for registering and tracking the positions of the objects. Using these sensors, the system may geometrically resolve the 3-dimensional position of the sensors based on information from or with respect to one or more cameras, signals, or sensors, etc. These surgical systems can therefore utilize position feedback to precisely guide movement of robotic arms and tools relative to a patients&#39; surgical site. Thus, there is a need for a system that efficiently and accurately provides neuronavigation registration and robotic trajectory guidance in a surgical environment. 
     Position recognition systems for robot-assisted surgeries often make use of registration fixtures as part of the aforesaid neuronavigation registration, robotic trajectory guidance, or for still other positioning and related functions for robotic-assisted surgery. Tracking markers are likewise used by position recognition systems and/or associated registration fixtures, and it is often necessary to have the positions of such tracking markers determined, registered, or otherwise subject to processing for purposes of the position recognition systems, navigation, or robotic trajectory guidance. In certain implementations, dynamic reference bases, referred to, at times, as DRBs, may be associated with the position recognition systems, including registration fixtures, stereotactic frames, and the like, and the aforementioned tracking markers may likewise be associated with such DRBs. 
     It is thus advantageous for position determinations of tracking markers or registration fixtures, including DRBs, to be accomplished efficiently and accurately. Registrations of tracking markers generally involve position and orientation relative to one or more of the registration fixture, patient, or anatomy to be operated upon, and such registration may need to be determined or maintained pre-operatively and again intra-operatively. 
     The need to employ GPS-assisted or other navigation protocols dependent on tracking markers and position determinations likewise may not be optimized when DRBs and their related positioning systems fall out of registration, or otherwise require repetitive verifications, registrations, repositionings, and the like. 
     To the extent certain of the determinations are associated with a non-sterile environment whereas other determinations are associated with a sterile environment, the foregoing determinations of position or registration are further complicated. 
     SUMMARY 
     According to some implementations, a surgical robot system is configured for surgery on an anatomical feature of a patient, and includes a surgical robot, a robot arm connected to such surgical robot, and an end-effector connected to the robot arm. One of the registration fixtures as discussed herein is affixed or otherwise secured in position with respect to a patient whose anatomical feature is of interest for the associated surgical procedure. A plurality of tracking markers have positions which are likewise registered with respect to such registration fixture. 
     The robot system includes one or more suitable processor circuits having memory associated therewith and machine-readable instructions to be executed by suitable operations of the processor circuit. 
     The registration fixture, in certain implementations, includes a detachable base, such as a detachable dynamic reference base, and such detachable dynamic reference base has a plurality of tracking markers mounted thereto. A mount associated with the registration fixture and/or the detachable dynamic reference base is adapted so that, after the system determines the positions of the tracking markers, the detachable dynamic reference base (“DRB”) may be reattached relative to the registration fixture or the robotic system and such reattachment is such that the tracking markers assume substantially the same positions as those previously determined positions of such tracking markers. 
     In still further implementations, the mount and detachable DRB are secured relative to each other by mounting members, with such mounting members having features to form a kinematic mount which operates to repeatedly attach the mount and the base at predetermined mating positions which vary by less than 15% between successive detachments and reattachments. 
     According to still further implementations, the mounting members may comprise mating pairs of contacts and receiving pins, with one contact on either the mount or the base and at least one receiving pin for engaging the contact on the other of the mount or the base. 
     In various additional implementations, a keyed flange, having mating or complementary portions on the detachable base and the mount, has features such that the base and mount are positionable in a single orientation. The keyed flange may take the form of a post extending from one of the opposing surfaces of the detachable base or the mount and a corresponding cut-out formed in the other of the detachable base or the mount, such cut-out being located to receive the post therein with little to no clearance, thereby assuring that the base and mount are positionable in such single orientation. 
     The mounting members may be in the form of a pair of cylindrical pins disposed on one of the opposing surfaces of the mount or the DRB, whereas the contacts on the other of the opposing surfaces may be in the form of hemispherical surfaces sized to engage opposing portions on each of the two pins of the respective pairs of pins. 
     The above-described system and its various features may be associated with a variety of related procedures or processes, collectively referred to herein as methods. One such method involves running a cranial procedure on a patient with a computer-implemented surgical robot of a corresponding robot system. The method involves establishing a sterile field; however, prior to establishing the sterile field, the patient is registered in the non-sterile field and incision points for the cranial procedure are marked. The registration of the patient includes performing a first, detachable mounting of a plurality of tracking markers in a first predetermined position and orientation relative to a patient registration fixture. After such mounting, a determination is made, by execution of suitable computer instructions, of a first position and first orientation for the tracking marker positions which correspond to the plurality of tracking markers. Thereafter, under this method, the plurality of tracking markers are detached from their previous mounting. After establishment of the sterile field, a second detachable mounting of the plurality of tracking markers is performed. During performance of the second detachable mounting, the tracking markers are prevented from being mounted other than in the first position and the first orientation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings: 
         FIG.  1 A  is an overhead view of an arrangement for locations of a robotic system, patient, surgeon, and other medical personnel during a surgical procedure, according to some embodiments; 
         FIG.  1 B  is an overhead view of an alternate arrangement for locations of a robotic system, patient, surgeon, and other medical personnel during a cranial surgical procedure, according to some embodiments; 
         FIG.  2    illustrates a robotic system including positioning of the surgical robot and a camera relative to the patient according to some embodiments; 
         FIG.  3    is a flowchart diagram illustrating computer-implemented operations for determining a position and orientation of an anatomical feature of a patient with respect to a robot arm of a surgical robot, according to some embodiments; 
         FIG.  4    is a diagram illustrating processing of data for determining a position and orientation of an anatomical feature of a patient with respect to a robot arm of a surgical robot, according to some embodiments; 
         FIGS.  5 A- 5 C  illustrate a system for registering an anatomical feature of a patient using a computerized tomography (CT) localizer, a frame reference array (FRA), and a dynamic reference base (DRB), according to some embodiments; 
         FIGS.  6 A and  6 B  illustrate a system for registering an anatomical feature of a patient using fluoroscopy (fluoro) imaging, according to some embodiments; 
         FIG.  7    illustrates a system for registering an anatomical feature of a patient using an intraoperative CT fixture (ICT) and a DRB, according to some embodiments; 
         FIGS.  8 A and  8 B  illustrate systems for registering an anatomical feature of a patient using a DRB and an X-ray cone beam imaging device, according to some embodiments; 
         FIG.  9    illustrates a system for registering an anatomical feature of a patient using a navigated probe and fiducials for point-to-point mapping of the anatomical feature, according to some embodiments; 
         FIG.  10    illustrates a two-dimensional visualization of an adjustment range for a centerpoint-arc mechanism, according to some embodiments; 
         FIG.  11    illustrates a two-dimensional visualization of virtual point rotation mechanism, according to some embodiments; 
         FIG.  12    is an isometric view of one possible implementation of an end-effector according to the present disclosure; 
         FIG.  13    is an isometric view of another possible implementation of an end-effector of the present disclosure; 
         FIG.  14    is a partial cutaway, isometric view of still another possible implementation of an end-effector according to the present disclosure; 
         FIG.  15    is a bottom angle isometric view of yet another possible implementation of an end-effector according to the present disclosure; 
         FIG.  16    is an isometric view of one possible tool stop for use with an end-effector according to the present disclosure; 
         FIGS.  17  and  18    are top plan views of one possible implementation of a tool insert locking mechanism of an end-effector according to the present disclosure; 
         FIGS.  19  and  20    are top plan views of the tool stop of  FIG.  16   , showing open and closed positions, respectively; 
         FIG.  21    is a first, isometric view of a detachable base in the form of a detachable dynamic reference base for use in the robot system disclosed herein and the associated registration systems; 
         FIG.  22    is a second, isometric view of the detachable base of  FIG.  21    turned over to show the underside of one of the surfaces; 
         FIG.  23    is a side, cross-sectional, enlarged view of components of detachable components of a registration fixture according to various implementations of this disclosure; and 
         FIG.  24    is an isometric view of a suitable mount according to certain implementations of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the description herein or illustrated in the drawings. The teachings of the present disclosure may be used and practiced in other embodiments and practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use embodiments of the present disclosure. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the principles herein can be applied to other embodiments and applications without departing from embodiments of the present disclosure. Thus, the embodiments are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the embodiments. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of the embodiments. 
     According to some other embodiments, systems for neuronavigation registration and robotic trajectory guidance, and related methods and devices are disclosed. In some embodiments, a first image having an anatomical feature of a patient, a registration fixture that is fixed with respect to the anatomical feature of the patient, and a first plurality of fiducial markers that are fixed with respect to the registration fixture is analyzed, and a position is determined for each fiducial marker of the first plurality of fiducial markers. Next, based on the determined positions of the first plurality of fiducial markers, a position and orientation of the registration fixture with respect to the anatomical feature is determined. A data frame comprising a second plurality of tracking markers that are fixed with respect to the registration fixture is also analyzed, and a position is determined for each tracking marker of the second plurality of tracking markers. Based on the determined positions of the second plurality of tracking markers, a position and orientation of the registration fixture with respect to a robot arm of a surgical robot is determined. Based on the determined position and orientation of the registration fixture with respect to the anatomical feature and the determined position and orientation of the registration fixture with respect to the robot arm, a position and orientation of the anatomical feature with respect to the robot arm is determined, which allows the robot arm to be controlled based on the determined position and orientation of the anatomical feature with respect to the robot arm. 
     Advantages of this and other embodiments include the ability to combine neuronavigation and robotic trajectory alignment into one system, with support for a wide variety of different registration hardware and methods. For example, as will be described in detail below, embodiments may support both computerized tomography (CT) and fluoroscopy (fluoro) registration techniques, and may utilize frame-based and/or frameless surgical arrangements. Moreover, in many embodiments, if an initial (e.g. preoperative) registration is compromised due to movement of a registration fixture, registration of the registration fixture (and of the anatomical feature by extension) can be re-established intraoperatively without suspending surgery and re-capturing preoperative images. 
     Referring now to the drawings,  FIG.  1 A  illustrates a surgical robot system  100  in accordance with an embodiment. Surgical robot system  100  may include, for example, a surgical robot  102 , one or more robot arms  104 , a base  106 , a display  110 , an end-effector  112 , for example, including a guide tube  114 , and one or more tracking markers  118 . The robot arm  104  may be movable along and/or about an axis relative to the base  106 , responsive to input from a user, commands received from a processing device, or other methods. The surgical robot system  100  may include a patient tracking device  116  also including one or more tracking markers  118 , which is adapted to be secured directly to the patient  210  (e.g., to a bone of the patient  210 ). As will be discussed in greater detail below, the tracking markers  118  may be secured to or may be part of a stereotactic frame that is fixed with respect to an anatomical feature of the patient  210 . The stereotactic frame may also be secured to a fixture to prevent movement of the patient  210  during surgery. 
     According to an alternative embodiment,  FIG.  1 B  is an overhead view of an alternate arrangement for locations of a robotic system  100 , patient  210 , surgeon  120 , and other medical personnel during a cranial surgical procedure. During a cranial procedure, for example, the robot  102  may be positioned behind the head  128  of the patient  210 . The robot arm  104  of the robot  102  has an end-effector  112  that may hold a surgical instrument  108  during the procedure. In this example, a stereotactic frame  134  is fixed with respect to the patient&#39;s head  128 , and the patient  210  and/or stereotactic frame  134  may also be secured to a patient base  211  to prevent movement of the patient&#39;s head  128  with respect to the patient base  211 . In addition, the patient  210 , the stereotactic frame  134  and/or or the patient base  211  may be secured to the robot base  106 , such as via an auxiliary arm  107 , to prevent relative movement of the patient  210  with respect to components of the robot  102  during surgery. Different devices may be positioned with respect to the patient&#39;s head  128  and/or patient base  211  as desired to facilitate the procedure, such as an intra-operative CT device  130 , an anesthesiology station  132 , a scrub station  136 , a neuro-modulation station  138 , and/or one or more remote pendants  140  for controlling the robot  102  and/or other devices or systems during the procedure. 
     The surgical robot system  100  in the examples of  FIGS.  1 A and/or  1 B  may also use a sensor, such as a camera  200 , for example, positioned on a camera stand  202 . The camera stand  202  can have any suitable configuration to move, orient, and support the camera  200  in a desired position. The camera  200  may include any suitable camera or cameras, such as one or more cameras (e.g., bifocal or stereophotogrammetric cameras), able to identify, for example, active or passive tracking markers  118  (shown as part of patient tracking device  116  in  FIG.  2   ) in a given measurement volume viewable from the perspective of the camera  200 . In this example, the camera  200  may scan the given measurement volume and detect the light that comes from the tracking markers  118  in order to identify and determine the position of the tracking markers  118  in three-dimensions. For example, active tracking markers  118  may include infrared-emitting markers that are activated by an electrical signal (e.g., infrared light emitting diodes (LEDs)), and/or passive tracking markers  118  may include retro-reflective markers that reflect infrared or other light (e.g., they reflect incoming IR radiation into the direction of the incoming light), for example, emitted by illuminators on the camera  200  or other suitable sensor or other device. 
     In many surgical procedures, one or more targets of surgical interest, such as targets within the brain for example, are localized to an external reference frame. For example, stereotactic neurosurgery may use an externally mounted stereotactic frame that facilitates patient localization and implant insertion via a frame mounted arc. Neuronavigation is used to register, e.g., map, targets within the brain based on pre-operative or intraoperative imaging. Using this pre-operative or intraoperative imaging, links and associations can be made between the imaging and the actual anatomical structures in a surgical environment, and these links and associations can be utilized by robotic trajectory systems during surgery. 
     According to some embodiments, various software and hardware elements may be combined to create a system that can be used to plan, register, place and verify the location of an instrument or implant in the brain. These systems may integrate a surgical robot, such as the surgical robot  102  of  FIGS.  1 A and/or  1 B , and may employ a surgical navigation system and planning software to program and control the surgical robot. In addition or alternatively, the surgical robot  102  may be remotely controlled, such as by nonsterile personnel. 
     The robot  102  may be positioned near or next to patient  210 , and it will be appreciated that the robot  102  can be positioned at any suitable location near the patient  210  depending on the area of the patient  210  undergoing the operation. The camera  200  may be separated from the surgical robot system  100  and positioned near or next to patient  210  as well, in any suitable position that allows the camera  200  to have a direct visual line of sight to the surgical field  208 . In the configuration shown, the surgeon  120  may be positioned across from the robot  102 , but is still able to manipulate the end-effector  112  and the display  110 . A surgical assistant  126  may be positioned across from the surgeon  120  again with access to both the end-effector  112  and the display  110 . If desired, the locations of the surgeon  120  and the assistant  126  may be reversed. The traditional areas for the anesthesiologist  122  and the nurse or scrub tech  124  may remain unimpeded by the locations of the robot  102  and camera  200 . 
     With respect to the other components of the robot  102 , the display  110  can be attached to the surgical robot  102  and in other embodiments, the display  110  can be detached from surgical robot  102 , either within a surgical room with the surgical robot  102 , or in a remote location. The end-effector  112  may be coupled to the robot arm  104  and controlled by at least one motor. In some embodiments, end-effector  112  can comprise a guide tube  114 , which is able to receive and orient a surgical instrument  108  used to perform surgery on the patient  210 . As used herein, the term “end-effector” is used interchangeably with the terms “end-effectuator” and “effectuator element.” Although generally shown with a guide tube  114 , it will be appreciated that the end-effector  112  may be replaced with any suitable instrumentation suitable for use in surgery. In some embodiments, end-effector  112  can comprise any known structure for effecting the movement of the surgical instrument  108  in a desired manner. 
     The surgical robot  102  is able to control the translation and orientation of the end-effector  112 . The robot  102  is able to move end-effector  112  along x-, y-, and z-axes, for example. The end-effector  112  can be configured for selective rotation about one or more of the x-, y-, and z-axis such that one or more of the Euler Angles (e.g., roll, pitch, and/or yaw) associated with end-effector  112  can be selectively controlled. In some embodiments, selective control of the translation and orientation of end-effector  112  can permit performance of medical procedures with significantly improved accuracy compared to conventional robots that use, for example, a six degree of freedom robot arm comprising only rotational axes. For example, the surgical robot system  100  may be used to operate on patient  210 , and robot arm  104  can be positioned above the body of patient  210 , with end-effector  112  selectively angled relative to the z-axis toward the body of patient  210 . 
     In some embodiments, the position of the surgical instrument  108  can be dynamically updated so that surgical robot  102  can be aware of the location of the surgical instrument  108  at all times during the procedure. Consequently, in some embodiments, surgical robot  102  can move the surgical instrument  108  to the desired position quickly without any further assistance from a physician (unless the physician so desires). In some further embodiments, surgical robot  102  can be configured to correct the path of the surgical instrument  108  if the surgical instrument  108  strays from the selected, preplanned trajectory. In some embodiments, surgical robot  102  can be configured to permit stoppage, modification, and/or manual control of the movement of end-effector  112  and/or the surgical instrument  108 . Thus, in use, in some embodiments, a physician or other user can operate the system  100 , and has the option to stop, modify, or manually control the autonomous movement of end-effector  112  and/or the surgical instrument  108 . Further details of surgical robot system  100  including the control and movement of a surgical instrument  108  by surgical robot  102  can be found in co-pending U.S. Patent Publication No. 2013/0345718, which is incorporated herein by reference in its entirety. 
     As will be described in greater detail below, the surgical robot system  100  can comprise one or more tracking markers configured to track the movement of robot arm  104 , end-effector  112 , patient  210 , and/or the surgical instrument  108  in three dimensions. In some embodiments, a plurality of tracking markers can be mounted (or otherwise secured) thereon to an outer surface of the robot  102 , such as, for example and without limitation, on base  106  of robot  102 , on robot arm  104 , and/or on the end-effector  112 . In some embodiments, such as the embodiment of  FIG.  3    below, for example, one or more tracking markers can be mounted or otherwise secured to the end-effector  112 . One or more tracking markers can further be mounted (or otherwise secured) to the patient  210 . In some embodiments, the plurality of tracking markers can be positioned on the patient  210  spaced apart from the surgical field  208  to reduce the likelihood of being obscured by the surgeon, surgical tools, or other parts of the robot  102 . Further, one or more tracking markers can be further mounted (or otherwise secured) to the surgical instruments  108  (e.g., a screw driver, dilator, implant inserter, or the like). Thus, the tracking markers enable each of the marked objects (e.g., the end-effector  112 , the patient  210 , and the surgical instruments  108 ) to be tracked by the surgical robot system  100 . In some embodiments, system  100  can use tracking information collected from each of the marked objects to calculate the orientation and location, for example, of the end-effector  112 , the surgical instrument  108  (e.g., positioned in the tube  114  of the end-effector  112 ), and the relative position of the patient  210 . Further details of surgical robot system  100  including the control, movement and tracking of surgical robot  102  and of a surgical instrument  108  can be found in U.S. Patent Publication No. 2016/0242849, which is incorporated herein by reference in its entirety. 
     In some embodiments, pre-operative imaging may be used to identify the anatomy to be targeted in the procedure. If desired by the surgeon the planning package will allow for the definition of a reformatted coordinate system. This reformatted coordinate system will have coordinate axes anchored to specific anatomical landmarks, such as the anterior commissure (AC) and posterior commissure (PC) for neurosurgery procedures. In some embodiments, multiple pre-operative exam images (e.g., CT or magnetic resonance (MR) images) may be co-registered such that it is possible to transform coordinates of any given point on the anatomy to the corresponding point on all other pre-operative exam images. 
     As used herein, registration is the process of determining the coordinate transformations from one coordinate system to another. For example, in the co-registration of preoperative images, co-registering a CT scan to an MR scan means that it is possible to transform the coordinates of an anatomical point from the CT scan to the corresponding anatomical location in the MR scan. It may also be advantageous to register at least one exam image coordinate system to the coordinate system of a common registration fixture, such as a dynamic reference base (DRB), which may allow the camera  200  to keep track of the position of the patient in the camera space in real-time so that any intraoperative movement of an anatomical point on the patient in the room can be detected by the robot system  100  and accounted for by compensatory movement of the surgical robot  102 . 
       FIG.  3    is a flowchart diagram illustrating computer-implemented operations  300  for determining a position and orientation of an anatomical feature of a patient with respect to a robot arm of a surgical robot, according to some embodiments. The operations  300  may include receiving a first image volume, such as a CT scan, from a preoperative image capture device at a first time (Block  302 ). The first image volume includes an anatomical feature of a patient and at least a portion of a registration fixture that is fixed with respect to the anatomical feature of the patient. The registration fixture includes a first plurality of fiducial markers that are fixed with respect to the registration fixture. The operations  300  further include determining, for each fiducial marker of the first plurality of fiducial markers, a position of the fiducial marker relative to the first image volume (Block  304 ). The operations  300  further include, determining, based on the determined positions of the first plurality of fiducial markers, positions of an array of tracking markers on the registration fixture (fiducial registration array or FRA) with respect to the anatomical feature (Block  306 ). 
     The operations  300  may further include receiving a tracking data frame from an intraoperative tracking device comprising a plurality of tracking cameras at a second time that is later than the first time (Block  308 ). The tracking frame includes positions of a plurality of tracking markers that are fixed with respect to the registration fixture (FRA) and a plurality of tracking markers that are fixed with respect to the robot. The operations  300  further include determining, for based on the positions of tracking markers of the registration fixture, a position and orientation of the anatomical feature with respect to the tracking cameras (Block  310 ). The operations  300  further include determining, based on the determined positions of the plurality of tracking markers on the robot, a position and orientation of the robot arm of a surgical robot with respect to the tracking cameras (Block  312 ). 
     The operations  300  further include determining, based on the determined position and orientation of the anatomical feature with respect to the tracking cameras and the determined position and orientation of the robot arm with respect to the tracking cameras, a position and orientation of the anatomical feature with respect to the robot arm (Block  314 ). The operations  300  further include controlling movement of the robot arm with respect to the anatomical feature, e.g., along and/or rotationally about one or more defined axis, based on the determined position and orientation of the anatomical feature with respect to the robot arm (Block  316 ). 
       FIG.  4    is a diagram illustrating a data flow  400  for a multiple coordinate transformation system, to enable determining a position and orientation of an anatomical feature of a patient with respect to a robot arm of a surgical robot, according to some embodiments. In this example, data from a plurality of exam image spaces  402 , based on a plurality of exam images, may be transformed and combined into a common exam image space  404 . The data from the common exam image space  404  and data from a verification image space  406 , based on a verification image, may be transformed and combined into a registration image space  408 . Data from the registration image space  408  may be transformed into patient fiducial coordinates  410 , which is transformed into coordinates for a DRB  412 . A tracking camera  414  may detect movement of the DRB  412  (represented by DRB  412 ′) and may also detect a location of a probe tracker  416  to track coordinates of the DRB  412  over time. A robotic arm tracker  418  determines coordinates for the robot arm based on transformation data from a Robotics Planning System (RPS) space  420  or similar modeling system, and/or transformation data from the tracking camera  414 . 
     It should be understood that these and other features may be used and combined in different ways to achieve registration of image space, i.e., coordinates from image volume, into tracking space, i.e., coordinates for use by the surgical robot in real-time. As will be discussed in detail below, these features may include fiducial-based registration such as stereotactic frames with CT localizer, preoperative CT or MRI registered using intraoperative fluoroscopy, calibrated scanner registration where any acquired scan&#39;s coordinates are pre-calibrated relative to the tracking space, and/or surface registration using a tracked probe, for example. 
     In one example,  FIGS.  5 A- 5 C  illustrate a system  500  for registering an anatomical feature of a patient. In this example, the stereotactic frame base  530  is fixed to an anatomical feature  528  of patient, e.g., the patient&#39;s head. As shown by  FIG.  5 A , the stereotactic frame base  530  may be affixed to the patient&#39;s head  528  prior to registration using pins clamping the skull or other method. The stereotactic frame base  530  may act as both a fixation platform, for holding the patient&#39;s head  528  in a fixed position, and registration and tracking platform, for alternatingly holding the CT localizer  536  or the FRA fixture  534 . The CT localizer  536  includes a plurality of fiducial markers  532  (e.g., N-pattern radio-opaque rods or other fiducials), which are automatically detected in the image space using image processing. Due to the precise attachment mechanism of the CT localizer  536  to the base  530 , these fiducial markers  532  are in known space relative to the stereotactic frame base  530 . A 3D CT scan of the patient with CT localizer  536  attached is taken, with an image volume that includes both the patient&#39;s head  528  and the fiducial markers  532  of the CT localizer  536 . This registration image can be taken intraoperatively or preoperatively, either in the operating room or in radiology, for example. The captured 3D image dataset is stored to computer memory. 
     As shown by  FIG.  5 B , after the registration image is captured, the CT localizer  536  is removed from the stereotactic frame base  530  and the frame reference array fixture  534  is attached to the stereotactic frame base  530 . The stereotactic frame base  530  remains fixed to the patient&#39;s head  528 , however, and is used to secure the patient during surgery, and serves as the attachment point of a frame reference array fixture  534 . The frame reference array fixture  534  includes a frame reference array (FRA), which is a rigid array of three or more tracked markers  539 , which may be the primary reference for optical tracking. By positioning the tracked markers  539  of the FRA in a fixed, known location and orientation relative to the stereotactic frame base  530 , the position and orientation of the patient&#39;s head  528  may be tracked in real time. Mount points on the FRA fixture  534  and stereotactic frame base  530  may be designed such that the FRA fixture  534  attaches reproducibly to the stereotactic frame base  530  with minimal (i.e., submillimetric) variability. These mount points on the stereotactic frame base  530  can be the same mount points used by the CT localizer  536 , which is removed after the scan has been taken. An auxiliary arm (such as auxiliary arm  107  of  FIG.  1 B , for example) or other attachment mechanism can also be used to securely affix the patient to the robot base to ensure that the robot base is not allowed to move relative to the patient. 
     As shown by  FIG.  5 C , a dynamic reference base (DRB)  540  may also be attached to the stereotactic frame base  530 . The DRB  540  in this example includes a rigid array of three or more tracked markers  542 . In this example, the DRB  540  and/or other tracked markers may be attached to the stereotactic frame base  530  and/or to directly to the patient&#39;s head  528  using auxiliary mounting arms  541 , pins, or other attachment mechanisms. Unlike the FRA fixture  534 , which mounts in only one way for unambiguous localization of the stereotactic frame base  530 , the DRB  540  in general may be attached as needed for allowing unhindered surgical and equipment access. Once the DRB  540  and FRA fixture  534  are attached, registration, which was initially related to the tracking markers  539  of the FRA, can be optionally transferred or related to the tracking markers  542  of the DRB  540 . For example, if any part of the FRA fixture  534  blocks surgical access, the surgeon may remove the FRA fixture  534  and navigate using only the DRB  540 . However, if the FRA fixture  534  is not in the way of the surgery, the surgeon could opt to navigate from the FRA markers  539 , without using a DRB  540 , or may navigate using both the FRA markers  539  and the DRB  540 . In this example, the FRA fixture  534  and/or DRB  540  uses optical markers, the tracked positions of which are in known locations relative to the stereotactic frame base  530 , similar to the CT localizer  536 , but it should be understood that many other additional and/or alternative techniques may be used. 
       FIGS.  6 A and  6 B  illustrate a system  600  for registering an anatomical feature of a patient using fluoroscopy (fluoro) imaging, according to some embodiments. In this embodiment, image space is registered to tracking space using multiple intraoperative fluoroscopy (fluoro) images taken using a tracked registration fixture  644 . The anatomical feature of the patient (e.g., the patient&#39;s head  628 ) is positioned and rigidly affixed in a clamping apparatus  643  in a static position for the remainder of the procedure. The clamping apparatus  643  for rigid patient fixation can be a three-pin fixation system such as a Mayfield clamp, a stereotactic frame base attached to the surgical table, or another fixation method, as desired. The clamping apparatus  643  may also function as a support structure for a patient tracking array or DRB  640  as well. The DRB may be attached to the clamping apparatus using auxiliary mounting arms  641  or other means. 
     Once the patient is positioned, the fluoro fixture  644  is attached the fluoro unit&#39;s x-ray collecting image intensifier (not shown) and secured by tightening clamping feet  632 . The fluoro fixture  644  contains fiducial markers (e.g., metal spheres laid out across two planes in this example, not shown) that are visible on 2D fluoro images captured by the fluoro image capture device and can be used to calculate the location of the x-ray source relative to the image intensifier, which is typically about 1 meter away contralateral to the patient, using a standard pinhole camera model. Detection of the metal spheres in the fluoro image captured by the fluoro image capture device also enables the software to de-warp the fluoro image (i.e., to remove pincushion and s-distortion). Additionally, the fluoro fixture  644  contains 3 or more tracking markers  646  for determining the location and orientation of the fluoro fixture  644  in tracking space. In some embodiments, software can project vectors through a CT image volume, based on a previously captured CT image, to generate synthetic images based on contrast levels in the CT image that appear similar to the actual fluoro images (i.e., digitally reconstructed radiographs (DRRs)). By iterating through theoretical positions of the fluoro beam until the DRRs match the actual fluoro shots, a match can be found between fluoro image and DRR in two or more perspectives, and based on this match, the location of the patient&#39;s head  628  relative to the x-ray source and detector is calculated. Because the tracking markers  646  on the fluoro fixture  644  track the position of the image intensifier and the position of the x-ray source relative to the image intensifier is calculated from metal fiducials on the fluoro fixture  644  projected on 2D images, the position of the x-ray source and detector in tracking space are known and the system is able to achieve image-to-tracking registration. 
     As shown by  FIG.  6 A and  6 B , two or more shots are taken of the head  628  of the patient by the fluoro image capture device from two different perspectives while tracking the array markers  642  of the DRB  640 , which is fixed to the registration fixture  630  via a mounting arm  641 , and tracking markers  646  on the fluoro fixture  644 . Based on the tracking data and fluoro data, an algorithm computes the location of the head  628  or other anatomical feature relative to the tracking space for the procedure. Through image-to-tracking registration, the location of any tracked tool in the image volume space can be calculated. 
     For example, in one embodiment, a first fluoro image taken from a first fluoro perspective can be compared to a first DRR constructed from a first perspective through a CT image volume, and a second fluoro image taken from a second fluoro perspective can be compared to a second DRR constructed from a second perspective through the same CT image volume. Based on the comparisons, it may be determined that the first DRR is substantially equivalent to the first fluoro image with respect to the projected view of the anatomical feature, and that the second DRR is substantially equivalent to the second fluoro image with respect to the projected view of the anatomical feature. Equivalency confirms that the position and orientation of the x-ray path from emitter to collector on the actual fluoro machine as tracked in camera space matches the position and orientation of the x-ray path from emitter to collector as specified when generating the DRRs in CT space, and therefore registration of tracking space to CT space is achieved. 
       FIG.  7    illustrates a system  700  for registering an anatomical feature of a patient using an intraoperative CT fixture (ICT) and a DRB, according to some embodiments. As shown in  FIG.  7   , in one application, a fiducial-based image-to-tracking registration can be utilized that uses an intraoperative CT fixture (ICT)  750  having a plurality of tracking markers  751  and radio-opaque fiducial reference markers  732  to register the CT space to the tracking space. After stabilizing the anatomical feature  728  (e.g., the patient&#39;s head) using clamping apparatus  730  such as a three-pin Mayfield frame and/or stereotactic frame, the surgeon will affix the ICT  750  to the anatomical feature  728 , DRB  740 , or clamping apparatus  730 , so that it is in a static position relative to the tracking markers  742  of the DRB  740 , which may be held in place by mounting arm  741  or other rigid means. A CT scan is captured that encompasses the fiducial reference markers  732  of the ICT  750  while also capturing relevant anatomy of the anatomical feature  728 . Once the CT scan is loaded in the software, the system auto-identifies (through image processing) locations of the fiducial reference markers  732  of the ICT within the CT volume, which are in a fixed position relative to the tracking markers of the ICT  750 , providing image-to-tracking registration. This registration, which was initially based on the tracking markers  751  of the ICT  750 , is then related to or transferred to the tracking markers  742  of the DRB  740 , and the ICT  750  may then be removed. 
       FIG.  8 A  illustrates a system  800  for registering an anatomical feature of a patient using a DRB and an X-ray cone beam imaging device, according to some embodiments. An intraoperative scanner  852 , such as an X-ray machine or other scanning device, may have a tracking array  854  with tracking markers  855 , mounted thereon for registration. Based on the fixed, known position of the tracking array  854  on the scanning device, the system may be calibrated to directly map (register) the tracking space to the image space of any scan acquired by the system. Once registration is achieved, the registration, which is initially based on the tracking markers  855  (e.g. gantry markers) of the scanner&#39;s array  854 , is related or transferred to the tracking markers  842  of a DRB  840 , which may be fixed to a clamping fixture  830  holding the patient&#39;s head  828  by a mounting arm  841  or other rigid means. After transferring registration, the markers on the scanner are no longer used and can be removed, deactivated or covered if desired. Registering the tracking space to any image acquired by a scanner in this way may avoid the need for fiducials or other reference markers in the image space in some embodiments. 
       FIG.  8 B  illustrates an alternative system  800 ′ that uses a portable intraoperative scanner, referred to herein as a C-arm scanner  853 . In this example, the C-arm scanner  853  includes a c-shaped arm  856  coupled to a movable base  858  to allow the C-arm scanner  853  to be moved into place and removed as needed, without interfering with other aspects of the surgery. The arm  856  is positioned around the patient&#39;s head  828  intraoperatively, and the arm  856  is rotated and/or translated with respect to the patient&#39;s head  828  to capture the X-ray or other type of scan that to achieve registration, at which point the C-arm scanner  853  may be removed from the patient. 
     Another registration method for an anatomical feature of a patient, e.g., a patient&#39;s head, may be to use a surface contour map of the anatomical feature, according to some embodiments. A surface contour map may be constructed using a navigated or tracked probe, or other measuring or sensing device, such as a laser pointer, 3D camera, etc. For example, a surgeon may drag or sequentially touch points on the surface of the head with the navigated probe to capture the surface across unique protrusions, such as zygomatic bones, superciliary arches, bridge of nose, eyebrows, etc. The system then compares the resulting surface contours to contours detected from the CT and/or MR images, seeking the location and orientation of contour that provides the closest match. To account for movement of the patient and to ensure that all contour points are taken relative to the same anatomical feature, each contour point is related to tracking markers on a DRB on the patient at the time it is recorded. Since the location of the contour map is known in tracking space from the tracked probe and tracked DRB, tracking-to-image registration is obtained once the corresponding contour is found in image space. 
       FIG.  9    illustrates a system  900  for registering an anatomical feature of a patient using a navigated or tracked probe and fiducials for point-to-point mapping of the anatomical feature  928  (e.g., a patient&#39;s head), according to some embodiments. Software would instruct the user to point with a tracked probe to a series of anatomical landmark points that can be found in the CT or MR image. When the user points to the landmark indicated by software, the system captures a frame of tracking data with the tracked locations of tracking markers on the probe and on the DRB. From the tracked locations of markers on the probe, the coordinates of the tip of the probe are calculated and related to the locations of markers on the DRB. Once  3  or more points are found in both spaces, tracking-to-image registration is achieved. As an alternative to pointing to natural anatomical landmarks, fiducials  954  (i.e., fiducial markers), such as sticker fiducials or metal fiducials, may be used. The surgeon will attach the fiducials  954  to the patient, which are constructed of material that is opaque on imaging, for example containing metal if used with CT or Vitamin E if used with MR. Imaging (CT or MR) will occur after placing the fiducials  954 . The surgeon or user will then manually find the coordinates of the fiducials in the image volume, or the software will find them automatically with image processing. After attaching a DRB  940  with tracking markers  942  to the patient through a mounting arm  941  connected to a clamping apparatus  930  or other rigid means, the surgeon or user may also locate the fiducials  954  in physical space relative to the DRB  940  by touching the fiducials  954  with a tracked probe while simultaneously recording tracking markers on the probe (not shown) and on the DRB  940 . Registration is achieved because the coordinates of the same points are known in the image space and the tracking space. 
     One use for the embodiments described herein is to plan trajectories and to control a robot to move into a desired trajectory, after which the surgeon will place implants such as electrodes through a guide tube held by the robot. Additional functionalities include exporting coordinates used with existing stereotactic frames, such as a Leksell frame, which uses five coordinates: X, Y, Z, Ring Angle and Arc Angle. These five coordinates are established using the target and trajectory identified in the planning stage relative to the image space and knowing the position and orientation of the ring and arc relative to the stereotactic frame base or other registration fixture. 
     As shown in  FIG.  10   , stereotactic frames allow a target location  1058  of an anatomical feature  1028  (e.g., a patient&#39;s head) to be treated as the center of a sphere and the trajectory can pivot about the target location  1058 . The trajectory to the target location  1058  is adjusted by the ring and arc angles of the stereotactic frame (e.g., a Leksell frame). These coordinates may be set manually, and the stereotactic frame may be used as a backup or as a redundant system in case the robot fails or cannot be tracked or registered successfully. The linear x,y,z offsets to the center point (i.e., target location  1058 ) are adjusted via the mechanisms of the frame. A cone  1060  is centered around the target location  1058 , and shows the adjustment zone that can be achieved by modifying the ring and arc angles of the Leksell or other type of frame. This figure illustrates that a stereotactic frame with ring and arc adjustments is well suited for reaching a fixed target location from a range of angles while changing the entry point into the skull. 
       FIG.  11    illustrates a two-dimensional visualization of virtual point rotation mechanism, according to some embodiments. In this embodiment, the robotic arm is able to create a different type of point-rotation functionality that enables a new movement mode that is not easily achievable with a 5-axis mechanical frame, but that may be achieved using the embodiments described herein. Through coordinated control of the robot&#39;s axes using the registration techniques described herein, this mode allows the user to pivot the robot&#39;s guide tube about any fixed point in space. For example, the robot may pivot about the entry point  1162  into the anatomical feature  1128  (e.g., a patient&#39;s head). This entry point pivoting is advantageous as it allows the user to make a smaller burr hole without limiting their ability to adjust the target location  1164  intraoperatively. The cone  1160  represents the range of trajectories that may be reachable through a single entry hole. Additionally, entry point pivoting is advantageous as it allows the user to reach two different target locations  1164  and  1166  through the same small entry burr hole. Alternately, the robot may pivot about a target point (e.g., location  1058  shown in  FIG.  10   ) within the skull to reach the target location from different angles or trajectories, as illustrated in  FIG.  10   . Such interior pivoting robotically has the same advantages as a stereotactic frame as it allows the user to approach the same target location  1058  from multiple approaches, such as when irradiating a tumor or when adjusting a path so that critical structures such as blood vessels or nerves will not be crossed when reaching targets beyond them. Unlike a stereotactic frame, which relies on fixed ring and arc articulations to keep a target/pivot point fixed, the robot adjusts the pivot point through controlled activation of axes and the robot can therefore dynamically adjust its pivot point and switch as needed between the modes illustrated in  FIGS.  10  and  11   . 
     Following the insertion of implants or instrumentation using the robot or ring and arc fixture, these and other embodiments may allow for implant locations to be verified using intraoperative imaging. Placement accuracy of the instrument or implant relative to the planned trajectory can be qualitatively and/or quantitatively shown to the user. One option for comparing planned to placed position is to merge a postoperative verification CT image to any of the preoperative images. Once pre- and post-operative images are merged and plan is shown overlaid, the shadow of the implant on postop CT can be compared to the plan to assess accuracy of placement. Detection of the shadow artifact on post-op CT can be performed automatically through image processing and the offset displayed numerically in terms of millimeters offset at the tip and entry and angular offset along the path. This option does not require any fiducials to be present in the verification image since image-to-image registration is performed based on bony anatomical contours. 
     A second option for comparing planned position to the final placement would utilize intraoperative fluoro with or without an attached fluoro fixture. Two out-of-plane fluoro images will be taken and these fluoro images will be matched to DRRs generated from pre-operative CT or MR as described above for registration. Unlike some of the registration methods described above, however, it may be less important for the fluoro images to be tracked because the key information is where the electrode is located relative to the anatomy in the fluoro image. The linear or slightly curved shadow of the electrode would be found on a fluoro image, and once the DRR corresponding to that fluoro shot is found, this shadow can be replicated in the CT image volume as a plane or sheet that is oriented in and out of the ray direction of the fluoro image and DRR. That is, the system may not know how deep in or out of the fluoro image plane the electrode lies on a given shot, but can calculate the plane or sheet of possible locations and represent this plane or sheet on the 3D volume. In a second fluoro view, a different plane or sheet can be determined and overlaid on the 3D image. Where these two planes or sheets intersect on the 3D image is the detected path of the electrode. The system can represent this detected path as a graphic on the 3D image volume and allow the user to reslice the image volume to display this path and the planned path from whatever perspective is desired, also allowing automatic or manual calculation of the deviation from planned to placed position of the electrode. Tracking the fluoro fixture is unnecessary but may be done to help de-warp the fluoro images and calculate the location of the x-ray emitter to improve accuracy of DRR calculation, the rate of convergence when iterating to find matching DRR and fluoro shots, and placement of sheets/planes representing the electrode on the 3D scan. 
     In this and other examples, it is desirable to maintain navigation integrity, i.e., to ensure that the registration and tracking remain accurate throughout the procedure. Two primary methods to establish and maintain navigation integrity include: tracking the position of a surveillance marker relative to the markers on the DRB, and checking landmarks within the images. In the first method, should this position change due to, for example, the DRB being bumped, then the system may alert the user of a possible loss of navigation integrity. In the second method, if a landmark check shows that the anatomy represented in the displayed slices on screen does not match the anatomy at which the tip of the probe points, then the surgeon will also become aware that there is a loss of navigation integrity. In either method, if using the registration method of CT localizer and frame reference array (FRA), the surgeon has the option to re-attach the FRA, which mounts in only one possible way to the frame base, and to restore tracking-to-image registration based on the FRA tracking markers and the stored fiducials from the CT localizer  536 . This registration can then be transferred or related to tracking markers on a repositioned DRB. Once registration is transferred the FRA can be removed if desired. 
     Referring now to  FIGS.  12 - 18    generally, with reference to the surgical robot system  100  shown in  FIG.  1 A , end-effector  112  may be equipped with components, configured, or otherwise include features so that one end-effector may remain attached to a given one of robot arms  104  without changing to another end-effector for multiple different surgical procedures, such as, by way of example only, Deep Brain Stimulation (DBS), Stereoelectroencephalography (SEEG), or Endoscopic Navigation and Tumor Biopsy. As discussed previously, end-effector  112  may be orientable to oppose an anatomical feature of a patient in the manner so as to be in operative proximity thereto, and, to be able to receive one or more surgical tools for operations contemplated on the anatomical feature proximate to the end-effector  112 . Motion and orientation of end-effector  112  may be accomplished through any of the navigation, trajectory guidance, or other methodologies discussed herein or as may be otherwise suitable for the particular operation. 
     End-effector  112  is suitably configured to permit a plurality of surgical tools  129  to be selectively connectable to end-effector  112 . Thus, for example, a stylet  113  ( FIG.  13   ) may be selectively attached in order to localize an incision point on an anatomical feature of a patient, or an electrode driver  115  ( FIG.  14   ) may be selectively attached to the same end-effector  112 . 
     With reference to the previous discussion of robot surgical system  100 , a processor circuit, as well as memory accessible by such processor circuit, includes various subroutines and other machine-readable instructions configured to cause, when executed, end-effector  112  to move, such as by GPS movement, relative to the anatomical feature, at predetermined stages of associated surgical operations, whether pre-operative, intra-operative or post-operative. 
     End-effector  112  includes various components and features to either prevent or permit end-effector movement depending on whether and which tools  129 , if any, are connected to end-effector  112 . Referring more particularly to  FIG.  12   , end-effector  112  includes a tool-insert locking mechanism  117  located on and connected to proximal surface  119 . Tool-insert locking mechanism  117  is configured so as to secure any selected one of a plurality of surgical tools, such as the aforesaid stylet  113 , electrode driver  115 , or any other tools for different surgeries mentioned previously or as may be contemplated by other applications of this disclosure. The securement of the tool by tool-insert locking mechanism  117  is such that, for any of multiple tools capable of being secured to locking mechanism  117 , each such tool is operatively and suitably secured at the predetermined height, angle of orientation, and rotational position relative to the anatomical feature of the patient, such that multiple tools may be secured to the same end-effector  112  in respective positions appropriate for the contemplated procedure. 
     Another feature of the end-effector  112  is a tool stop  121  located on distal surface  123  of end-effector  112 , that is, the surface generally opposing the patient. Tool stop  121  has a stop mechanism  125  and a sensor  127  operatively associated therewith, as seen with reference to  FIGS.  16 ,  19 , and  20   . Stop mechanism  125  is mounted to end-effector  112  so as to be selectively movable relative thereto between an engaged position to prevent any of the tools from being connected to end-effector  112  and a disengaged position which permits any of the tools  129  to be selectively connected to end-effector  112 . Sensor  127  may be located on or within the housing of end-effector  112  at any suitable location ( FIGS.  12 ,  14 ,  16   ) so that sensor  127  detects whether stop mechanism  125  is in the engaged or disengaged position. Sensor  127  may assume any form suitable for such detection, such as any type of mechanical switch or any type of magnetic sensor, including Reed switches, Hall Effect sensors, or other magnetic field detecting devices. In one possible implementation, sensor  127  has two portions, a Hall Effect sensor portion (not shown) and a magnetic portion  131 , the two portions moving relative to each other so as to generate and detect two magnetic fields corresponding to respective engaged and disengaged position. In the illustrated implementation, the magnetic portion comprises two rare earth magnets  131  which move relative to the complementary sensing portion (not shown) mounted in the housing of end effector  112  in operative proximity to magnets  131  to detect change in the associated magnetic field from movement of stop mechanism  125  between engaged and disengaged positions. In this implementation the Hall effect sensor is bipolar and can detect whether a North pole or South pole of a magnet opposes the sensor. Magnets  131  are configured so that the North pole of one magnet faces the path of the sensor and the South pole of the other magnet faces the path of the sensor. In this configuration, the sensor senses an increased signal when it is near one magnet (for example, in disengaged position), a decreased signal when it is near the other magnet (for example, in engaged position), and unchanged signal when it is not in proximity to any magnet. In this implementation, in response to detection of stop mechanism  125  being in the disengaged position shown in  FIGS.  13  and  19   , sensor  127  causes the processor of surgical robot system  100  to execute suitable instructions to prevent movement of end-effector  112  relative to the anatomical feature. Such movement prevention may be appropriate for any number of reasons, such as when a tool is connected to end-effector  112 , such tool potentially interacting with the anatomical feature of the patient. 
     Another implementation of a sensor  127  for detecting engaged or disengaged tool stop mechanism  125  could comprise a single magnet behind the housing (not shown) and two Hall Effect sensors located where magnets  131  are shown in the preferred embodiment. In such a configuration, monopolar Hall Effect sensors are suitable and would be configured so that Sensor  1  detects a signal when the magnet is in proximity due to the locking mechanism being disengaged, while Sensor  2  detects a signal when the same magnet is in proximity due to the locking mechanism being engaged. Neither sensor would detect a signal when the magnet is between positions or out of proximity to either sensor. Although a configuration could be conceived in which a sensor is active for engaged position and inactive for disengaged position, a configuration with three signals indicating engaged, disengaged, or transitional is preferred to ensure correct behavior in case of power failure. 
     End-effector  112 , tool stop  121 , and tool-insert locking mechanism  117  each have co-axially aligned bores or apertures such that any selected one of the plurality of surgical tools  129  may be received through such bores and apertures. In this implementation end-effector has a bore  133  and tool stop  121  and tool-insert locking mechanism  117  have respective apertures  135  and  137 . Stop mechanism  125  includes a ring  139  axially aligned with bore  133  and aperture  135  of tool stop  121 . Ring  139  is selectively, manually rotatable in the directions indicated by arrow A ( FIG.  16   ) so as to move stop mechanism  125  between the engaged position and the disengaged position. 
     In one possible implementation, the selective rotation of ring  139  includes features which enable ring  139  to be locked in either the disengaged or engaged position. So, for example, as illustrated, a detent mechanism  141  is located on and mounted to ring  139  in any suitable way to lock ring  139  against certain rotational movement out of a predetermined position, in this case, such position being when stop mechanism  125  is in the engaged position. Although various forms of detent mechanism are contemplated herein, one suitable arrangement has a manually accessible head extending circumferentially outwardly from ring  139  and having a male protrusion (not shown) spring-loaded axially inwardly to engage a corresponding female detent portion (not shown). Detent mechanism  141 , as such, is manually actuatable to unlock ring  139  from its engaged position to permit ring  139  to be manually rotated to cause stop mechanism  125  to move from the engaged position ( FIG.  20   ) to the disengaged position ( FIG.  19   ). 
     Tool stop  121  includes a lever arm  143  pivotally mounted adjacent aperture  135  of tool stop  121  so end of lever arm  143  selectively pivots in the directions indicated by arrow B (FIGS.  16 ,  19  and  20 ). Lever arm  143  is operatively connected to stop mechanism  125 , meaning it closes aperture  135  of tool stop  121  in response to stop mechanism  125  being in the engaged position, as shown in  FIG.  20   . Lever arm  143  is also operatively connected so as to pivot back in direction of arrow B to open aperture  135  in response to stop mechanism  125  being in the disengaged position. As such, movement of stop mechanism  125  between engaged and disengaged positions results in closure or opening of aperture  135 , respectively, by lever arm  143 . 
     Lever arm  143 , in this implementation, is not only pivotally mounted adjacent aperture  135 , but also pivots in parallel with a distal plane defined at a distal-most point of distal surface  123  of end-effector  112 . In this manner, any one of the surgical tools  129 , which is attempted to be inserted through bore  133  and aperture  135 , is stopped from being inserted past the distal plane in which lever arm  143  rotates to close aperture  135 . 
     Turning now to tool-insert locking mechanism  117  ( FIG.  13 ,  17 ,  18   ), a connector  145  is configured to meet with and secure any one of the surgical tools  129  at their appropriate height, angle of orientation, and rotational position relative to the anatomical feature of the patient. In the illustrated implementation, connector  145  comprises a rotatable flange  147  which has at least one slot  149  formed therein to receive therethrough a corresponding tongue  151  associated with a selected one of the plurality of tools  129 . So, for example, in  FIG.  14   , the particular electrode driver  115  has multiple tongues, one of which tongue  151  is shown. Rotatable flange  147 , in some implementations, may comprise a collar  153 , which collar, in turn, has multiple ones of slots  149  radially spaced on a proximally oriented surface  155 , as best seen in  FIG.  12   . Multiple slots  147  arranged around collar  153  are sized or otherwise configured so as to receive therethrough corresponding ones of multiple tongues  151  associated with a selected one of the plurality of tools  129 . Therefore, as seen in  FIG.  13   , multiple slots  149  and corresponding tongues  151  may be arranged to permit securing of a selected one of the plurality of tools  129  only when selected tool is in the correct, predetermined angle of orientation and rotational position relative to the anatomical feature of the patient. Similarly, with regard to the electrode driver shown in  FIG.  14   , tongues  151  (one of which is shown in a cutaway of  FIG.  14   ) have been received in radially spaced slots  149  arrayed so that electrode driver  115  is received at the appropriate angle of orientation and rotational position. 
     Rotatable flange  147  has, in this implementation, a grip  173  to facilitate manual rotation between an open and closed position as shown in  FIGS.  17  and  18   , respectively. As seen in  FIG.  17   , multiple sets of mating slots  149  and tongues  151  are arranged at different angular locations, in this case, locations which may be symmetric about a single diametric chord of a circle but otherwise radially asymmetric, and at least one of the slots has a different dimension or extends through a different arc length than other slots. In this slot-tongue arrangement, and any number of variations contemplated by this disclosure, there is only one rotational position of the tool  129  (or adapter  155  discussed later) to be received in tool-insert locking mechanism  117  when rotatable flange  147  is in the open position shown in  FIG.  17   . In other words, when the user of system  100  moves a selected tool  129  (or tool adapter  155 ) to a single appropriate rotational position, corresponding tongues  151  may be received through slots  149 . Upon placement of tongues  151  into slots  149 , tongues  151  confront a base surface  175  within connector  145  of rotatable flange  147 . Upon receiving tongues  151  into slots  149  and having them rest on underlying base surface  175 , dimensions of tongues  151  and slots  149 , especially with regard to height relative to rotatable flange  147 , are selected so that when rotatable flange  147  is rotated to the closed position, flange portions  157  are radially translated to overlie or engage portions of tongues  151 , such engagement shown in  FIG.  18    and affixing tool  129  (or adapter  155 ) received in connector  145  at the desired, predetermined height, angle of orientation, and rotational position relative to the anatomical feature of the patient. 
     Tongues  151  described as being associated with tools  129  may either be directly connected to such tools  129 , and/or tongues  151  may be located on and mounted to the above-mentioned adapter  155 , such as that shown in  FIGS.  12 ,  17  and  18   , such adapter  155  configured to interconnect at least one of the plurality of surgical tools  129  with end-effector  112 . In the described implementation, adapter  155  includes two operative portions—a tool receiver  157  adapted to connect the selected one or more surgical tools  129 , and the second operative part being one or more tongues  151  which may, in this implementation, be mounted and connected to the distal end of adapter  155 . 
     Adapter  155  has an outer perimeter  159  which, in this implementation, is sized to oppose an inner perimeter  161  of rotatable flange  147 . Adapter  155  extends between proximal and distal ends  163 ,  165 , respectively and has an adapter bore  167  extending between ends  163 ,  165 . Adapter bore  167  is sized to receive at least one of the plurality of surgical tools  129 , and similarly, the distance between proximal and distal ends  163 ,  165  is selected so that at least one of tools  129  is secured to end-effector  112  at the predetermined, appropriate height for the surgical procedure associated with such tool received in adapter bore  167 . 
     In one possible implementation, system  100  includes multiple ones of adapter  155 , configured to be interchangeable inserts  169  having substantially the same, predetermined outer perimeters  159  to be received within inner perimeter  161  of rotatable flange  147 . Still further in such implementation, the interchangeable inserts  169  have bores of different, respective diameters, which bores may be selected to receive corresponding ones of the tools  129  therein. Bores  167  may comprise cylindrical bushings having inner diameters common to multiple surgical tools  129 . One possible set of diameters for bores  167  may be  12 ,  15 , and  17  millimeters, suitable for multiple robotic surgery operations, such as those identified in this disclosure. 
     In the illustrated implementation, inner perimeter  161  of rotatable flange  147  and outer perimeter  159  of adapter  155  are circular, having central, aligned axes and corresponding radii. Slots  149  of rotatable flange  147  extend radially outwardly from the central axis of rotatable flange  147  in the illustrated implementation, whereas tongues  151  of adapter  155  extend radially outwardly from adapter  155 . 
     In still other implementations, end-effector  112  may be equipped with at least one illumination element  171  ( FIGS.  14  and  15   ) orientable toward the anatomical feature to be operated upon. Illumination element  171  may be in the form of a ring of LEDs  177  ( FIG.  14   ) located within adapter  167 , which adapter is in the form of a bushing secured to tool locking mechanism  117 . Illumination element  171  may also be a single LED  179  mounted on the distal surface  123  of end-effector  112 . Whether in the form of LED ring  177 or a single element LED  179  mounted on distal surface of end-effector  112 , or any other variation, the spacing and location of illumination element or elements  171  may be selected so that tools  129  received through bore  133  of end-effector  112  do not cast shadows or otherwise interfere with illumination from element  171  of the anatomical feature being operated upon. 
     The operation and associated features of end-effector  112  are readily apparent from the foregoing description. Tool stop  121  is rotatable, selectively lockable, and movable between engaged and disengaged positions, and a sensor prevents movement of end-effector  112  when in such disengaged position, due to the potential presence of a tool which may not be advisably moved during such disengaged position. Tool-insert locking mechanism  117  is likewise rotatable between open and closed positions to receive one of a plurality of interchangeable inserts  169  and tongues  151  of such inserts, wherein selected tools  129  may be received in such inserts  169 ; alternately, tongues  151  may be otherwise associated with tools  129 , such as by having tongues  151  directly connected to such tools  129 , which tongue-equipped tools likewise may be received in corresponding slots  149  of tool-insert locking mechanism  117 . Tool-insert locking mechanism  117  may be rotated from its open position in which tongues  151  have been received in slots  149 , to secure associated adapters  155  and/or tools  129  so that they are at appropriate, respective heights, angles of orientation, and rotational positions relative to the anatomical feature of the patient. 
     For those implementations with multiple adapters  155 , the dimensions of such adapters  155 , including bore diameters, height, and other suitable dimensions, are selected so that a single or a minimized number of end-effectors  112  can be used for a multiplicity of surgical tools  129 . Adapters  155 , such as those in the form of interchangeable inserts  169  or cylindrical bushings, may facilitate connecting an expanded set of surgical tools  129  to the end-effector  112 , and thus likewise facilitate a corresponding expanded set of associated surgical features using the same end-effector  112 . 
     Another possible embodiment of surgical robot system  100  shown in  FIG.  1 A  is described below and shown with reference to  FIGS.  21 - 24   . 
     A base in the form of a dynamic reference base (“DRB”)  1040  is shown and described and is suitable for use with any suitable registration fixture or registration system operatively associated with surgical robot system  100 , such as systems  500  ( FIGS.  5 A- 5 C ),  600  ( FIGS.  6 A- 6 B ),  700  ( FIG.  7   ),  800  ( FIGS.  8 A- 8 B ), and  900  ( FIG.  9   ). DRB  1040  includes features and corresponding structures, as shown and described below, to enable DRB  1040  not only to be attached relative to the patient anatomy of surgical interest and to be used in associated registration processes either pre- or intra-operatively, but also to be detached and reattached without losing its previously determined registration. Such features have advantages such as increasing workflow flexibility by allowing surgeons and other medical practitioners to use robotic system  100  and its related registration systems more efficiently, potentially avoiding the need for re-registration, as may be needed when using robot system  100  in both the non-sterile and sterile stages of a procedure, or to otherwise increase efficiency by avoiding loss of registration when DRB  1040  is attached and registered at one point in time, detached, and then subsequently reattached. 
     DRB  1040  may be used and secured in manners similar to those discussed with reference to DRBs  540 ,  640 ,  740 ,  840 , and  940 , except that DRB  1040  includes features, as mentioned, to permit detachment and reattachment without loss of previously determined registration under most circumstances. DRB  1040  may comprise or be integral with any suitable registration fixture, or DRB  1040  may be connected to or otherwise may be associated with any of the various registration fixtures shown and described herein with reference to  FIGS.  1 - 9   . DRB  1040  likewise may be used in still further alternate embodiments associated with any of the wide variety of registration hardware and related methods, whether by computerized tomography (CT) or fluoroscopy (fluoro) registration techniques and likewise may utilize either frame-based configurations or frameless arrangements. In the implementations illustrated in  FIGS.  5 A- 5 C,  6 A- 6 B,  7 ,  8 A- 8 B, and  9   , DRB  1040  may be detachably mounted to a mounting arm, auxiliary mounting arm, or other suitable location on the registration fixture, including, for example, a patient stabilization device, stereotactic frame, FRA fixtures, and the like, with mount  1051  suitably interposed between DRB  1040  and its fixation location on the registration fixture. 
     To the ends of enhancing registration of DRB  1040  during repeated attachments and detachments, DRB  1040  includes or is operatively associated with structures which permit DRB  1040  to be mounted not only detachably, but without losing registration in most circumstances. In the illustrated implementation, such structures include a mount  1051 . Referring to  FIGS.  21 - 24   , in one suitable implementation, mount  1051  is secured to one planar surface  1053  of DRB  1040 , which, in the orientation shown in  FIGS.  21  and  22   , may be thought of as the underside of DRB  1040 . Opposite underside surface  1053 , DRB  1040  has a planar surface  1057  which, in the orientation of  FIG.  21   , may be considered the upper or top side of DRB  1040  as shown . Mount  1051  is interposed between DRB  1040 , on the one hand, and the registration fixture, mounting arm, or other component of robotic system  100 , on the other hand. A suitable fastener, such as a manually operable threaded handle or screw  1055  secures both DRB  1040  and interposed mount  1051  to the appropriate location on the registration fixture or other location. In the illustrated implementation, screw  1055  is threadably received in opposing threaded portions of the registration fixture or other mounting location, so as to clamp or otherwise hold DRB  1040  to mount  1051 . DRB  1040  has a set of tracking markers, such as those shown in  FIGS.  5 - 9    as  542 ,  642 ,  742 ,  842 , and  942 , each such tracking marker secured at a respective one of posts  1059 . 
     Certain features on opposing surfaces of DRB  1040  and mount  1051  act to position DRB  1040  consistently between successive attachments, detachments, and reattachments. Given the consistent reattachment position and orientation afforded by DRB  1040  and its associated mount  1051 , a previously determined position of the set of tracking markers mounted to DRB  1040 , would also be identical or substantially similar to a subsequently determined position of such tracking markers, if and when DRB  1040  is detached and then reattached. As such, the registration procedure associated with the determination of tracking marker positions relative to components of the robotic surgical system itself, such as the robot arm, patient fixation devices, registration fixtures, and the anatomical feature which is of interest, all such registration parameters may be replicated between successive attachments, detachments, and reattachments of DRB  1040  and its associated mount  1051 , under most circumstances. 
     Referring more particularly to  FIGS.  22 - 24   , mount  1051  has a planar mounting surface  1061  which is brought into an opposing relationship with surface  1053  of DRB  1040  when secured to the appropriate component of robot system  100 . Mounting surface  1061  comprises a central area with portions extending therefrom to terminate in an arcuate perimeter  1065 , which perimeter, in this implementation, comprises a circle. Mounting surface  1061  has disposed thereon three sets of receiving pins  1063  at radially spaced locations on mounting surface  1061 . As such, receiving pins  1063 , in this implementation, are spaced about such arcuate perimeter by angles ranging from 110° to 130°, or at about 120°. 
     Underside  1053  of DRB  1040  which, when suitably connected, opposes mounting surface  1061  of mount  1051 , includes contacts  1066  at radially spaced locations corresponding to those of receiving pins  1063 . Such contacts  1066  in this implementation may be in the form of hemispherical surfaces  1067  which are sized and otherwise configured to engage opposing portions on each of the two pins of respective pairs of receiving pins  1063  when DRB  1040  and mount  1051  are clamped to each other. 
     Detachable DRB  1040  and its corresponding mount  1051  are further configured so as to be positionable in a single orientation by means of the selective engagement of at least one keyed flange  1068 . Keyed flange  1068  in this implementation comprises mating portions located on respective opposing surfaces of mount  1051  and detachable DRB  1040 , such mating portions comprising a post  1069  extending from one of the opposing surfaces of the mount and the base and a corresponding cut-out  1071  formed in the other of the opposing surfaces. In this implementation, cut-out  1071  is formed in the body of mount  1051  and receives therein post  1069  extending from underside  1053  of detachable DRB  1040 . Cut-out  1071  may be sized or otherwise adapted to receive post  1069  therein with little to no clearance, so as to further assure attachment of DRB  1040  and mount  1051  in the required single orientation and position. 
     Respective receiving pins  1063  and opposing contacts  1066  comprise a plurality of mounting members  1073  for detachably securing DRB  1040  and mount  1051 , and along with keyed flange  1068 , cause DRB  1040  and its associated tracking markers  1042  to be positionable in a consistent orientation between successive detachments and reattachments relative to other components against which tracking markers  1042  have been registered. Although mounting members  1073  comprise opposing sets of receiving pins  1063  and hemispherical surfaces  1067  in this implementation, mounting members  1073  may assume alternate forms, including one or more contacts on either one of the mount  1041  and the dynamic reference base  1040  and one or more receiving pins having a configuration or configurations different from the pairs of cylindrical receiving pins shown and described in  FIGS.  21 - 24   . Whatever the exact configuration of mounting members  1073 , together they form a kinematic mount having opposing portions between the mount  1051  and DRB  1040  to urge such components to predetermined mating positions, such predetermined mating positions characterized by respective angular orientations that vary by less than 15% between successive detachments and reattachments of the mount  1041  and base  1040 . 
     Robotic system  100  may include one or more processor circuits, memory accessible to such processor circuit or circuits, and suitable machine readable instructions to perform various registration functions or otherwise take advantage of the above-described detachable DRB  1040 , mount  1041 , and its kinematic mounting members  1073  permitting attachment and reattachment without significant variation in position or orientation. To that end, tracking markers associated with DRB  1040  may comprise four of the tracking markers as shown in previous embodiments herein at spaced locations defining corners of a quadrilateral and the corresponding tracking marker positions may likewise correspond to positions registered using the registration systems previously disclosed herein. The mounting locations of tracking markers may comprise registered verification values in such registration systems. 
     Suitable programming, when executed, may compare first and second sets of verification values corresponding to multiple attachments of DRB  1040  to registration fixtures disclosed hereunder. Thus, for example, suitable programming may compare the mounting locations of tracking markers on DRB  1040  pre-operatively, such as when the patient is being draped in a nonsterile field, and a subsequent set of verification values may correspond to intra-operative reattachment of DRB  1040 . Programming determines substantial identity or non-identity of the two sets of verification values, and the kinematic mount and other features of mounting members  1073  discussed herein assure substantial identity between the two sets of verification values under most circumstances. 
     Robotic system  100  may include suitable programming in the form of a navigation system to perform navigational functions preoperatively and in a nonsterile environment, such navigation functions facilitating the marking of incisions and the performance of navigation integrity checks. In the context of such navigation functions, instructions may be executed preoperatively after determination of a first set of tracking marker positions, as well as a corresponding first position and first orientation of a registration fixture associated with a contemplated robotic surgical procedure. Thereafter, navigation functions may be executable by robotic system  100  intra-operatively, after detachment and reattachment of DRB  1040  to mount  1051 , and after a determination of identity between the first set of tracking marker positions and a second set of the tracking marker positions. 
     Use and operation of the features and structures of a registration fixture equipped with DRB  1040  and mount  1051  is readily appreciated from the foregoing description. In one possible method, performance of a cranial procedure on a patient takes place with a computer-implemented surgical robot of a corresponding robot system. In the contemplated procedure, a sterile field is established and, prior to establishing such sterile field, the patient is registered, including marking, incision points for the cranial procedure, and various components of the robotic system are registered with respect to each other and/or anatomical features of the patient related to the contemplated operation. The step of registering the patient may include performing a first, detachable mounting of a plurality of tracking markers in a first predetermined position and corresponding first orientation relative to a patient registration fixture and determining, by means of computer instructions executed by a computer processor, a plurality of tracking marker positions corresponding to the aforesaid plurality of tracking markers. The procedure may then involve detaching the plurality of tracking markers, such as would occur upon detachment of DRB  1040  on which such plurality of tracking markers are secured in known positions. 
     Subsequently, after establishing a sterile field, DRB  1040  may be reattached or remounted, along with its plurality of tracking markers, by aligning the mating, mounting members  1073  on opposing surfaces of DRB  1040  and mount  1051 . Such mounting members  1073  thus have the effect of realigning the tracking markers on DRB  1040  with the previously determined registration of the patient registration fixture to which DRB  1040  is being attached. As such, tracking markers and the registration fixture are only mountable relative to each other in a second, position which has the same registration as the first previously determined position. 
     In still other possible methods according to this disclosure, computer instructions of the robotic system may mark incisions or otherwise perform registration functions using GPS-assisted navigation instructions of the system. The system likewise may perform navigational integrity checks before or after establishing the sterile field, pre-operatively or intra-operatively, and detachable DRB  1040  and corresponding mount  1051  assure the success of such navigational integrity checks. 
     In the above-description of various embodiments of present inventive concepts, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of present inventive concepts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     When an element is referred to as being “connected”, “coupled”, “responsive”, or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected”, “directly coupled”, “directly responsive”, or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout. Furthermore, “coupled”, “connected”, “responsive”, or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another element/operation. Thus a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification. 
     As used herein, the terms “comprise”, “comprising”, “comprises”, “include”, “including”, “includes”, “have”, “has”, “having”, or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, integers, elements, steps, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation “e.g.”, which derives from the Latin phrase “exempli gratia,” may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation “i.e.”, which derives from the Latin phrase “id est,” may be used to specify a particular item from a more general recitation. 
     Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s). 
     These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof. 
     It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. 
     Although several embodiments of inventive concepts have been disclosed in the foregoing specification, it is understood that many modifications and other embodiments of inventive concepts will come to mind to which inventive concepts pertain, having the benefit of teachings presented in the foregoing description and associated drawings. It is thus understood that inventive concepts are not limited to the specific embodiments disclosed hereinabove, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. It is further envisioned that features from one embodiment may be combined or used with the features from a different embodiment(s) described herein. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described inventive concepts, nor the claims which follow. The entire disclosure of each patent and patent publication cited herein is incorporated by reference herein in its entirety, as if each such patent or publication were individually incorporated by reference herein. Various features and/or potential advantages of inventive concepts are set forth in the following claims.