Patent Publication Number: US-2020297429-A1

Title: Trackable protective packaging for tools and methods for calibrating tool installation using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The subject application claims priority to and all the benefits of U.S. Provisional Patent Application No. 62/820,577, filed Mar. 19, 2019, the contents of which are hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     A surgical device, such as a robot, often receives a tool or instrument for use during a surgical procedure. The tool may be a cutting accessory, such as a saw, bur drill, having a head with sharp features configured to resect tissue such as bone. Exposed handling of the tool may result in surgical site infection, injury, and other undesirable consequences. For these reasons, such tools often require a type of protective packaging to prevent inadvertent exposure before and during installation. 
     A working portion of the tool (e.g., such as the burring portion) must be precisely known by the system in order to effect proper control of the surgical device. Navigation systems are often utilized with surgical systems to track surgical devices, the patient, and additional tools that may be utilized in the surgical procedure. The navigation system often utilizes markers or trackers that are attached to the objects that need to be tracked. 
     Tool accessories, such as those mentioned above, are interchangeably installed, often operate a high rate of movement and have high exposure to the surgical site thereby requiring sterilization. Therefore, markers or trackers on the tool may negatively affect physical performance of the tool or may be impossible to practically implement on the tool. Furthermore, markers on the tool would likely be destroyed during sterilization. For these reasons, such tool accessories are often not directly tracked by the navigation system. 
     In such situations, there may be no way of knowing whether the tool is properly installed to the surgical device. There may be situations where the tool appears to be properly installed to the operator, when in fact, the tool may be slightly (e.g., by a few millimeters) mis-aligned or not fully seated. 
     Prior techniques for confirming tool installation require additional instruments, such as tracked digitization devices, that are used to digitize certain points on the tool for calibration purposes. However, such techniques require additional tools and operator steps thereby increasing operating time and costs. Additionally, digitization techniques may produce measurements that are less accurate because the process requires manual operator involvement in digitizing. For example, the actual digitization point may deviate from the digitization point expected by the system. 
     Another prior method to assess installation accuracy is to use a custom end effector for a robotic system whereby the end effector has markers or tracking elements detectable by the navigation system and the tool accessory is already in a pre-installed, fixed position, relative to the end effector. In such instances, the robot must move to certain poses to implement a calibration process. In these poses, a kinematic location of the robot is known to the system and the locations of the tracking elements on the end effector are compared to the kinematic robot locations to assess accuracy. However, such methods are not suitable for end effectors that can accept different tools. Furthermore, the end effector must be customized with the given tool and therefore, this increases costs and complexity in end effector versions. Additionally, this technique requires the robot to assume certain poses, thereby increasing operating room time. 
     Techniques designed to overcome one or more of the aforementioned disadvantages are desired. 
     SUMMARY 
     In one example, a method for operating a system is provided, the system comprising a surgical device and a tool for mounting to the surgical device, the tool including a working portion having a tool center point, a protective packaging for retaining the working portion, the protective packaging comprising trackable features having a predetermined state defined relative to an actual state of the tool center point, one or more controllers configured to store the predetermined states of the trackable features and to store an expected state of the tool center point based on an expected condition in which the tool is properly mounted to the surgical device, and a localizer, the method comprising: detecting, with the localizer, actual states of the trackable features in a coordinate system; determining, with the one or more controllers, the actual state of the tool center point in the coordinate system based on the actual states of the trackable features detected by the localizer and the predetermined state of the trackable features defined relative to the actual state of the tool center point; comparing, with the one or more controllers, the actual state and expected state of the tool center point; and evaluating, with the one or more controllers, whether the tool is properly mounted to the surgical device based on comparing the actual state and expected state of the tool center point. 
     In another example, a system is provided. The system comprising: a surgical device; a tool configured to mount to the surgical device and comprising a working portion having a tool center point; a protective packaging configured to retain the working portion of the tool, the protective packaging comprising trackable features having a predetermined state defined relative to an actual state of the tool center point; one or more controllers coupled to the surgical device and configured to store the predetermined states of the trackable features and to store an expected state of the tool center point based on an expected condition in which the tool is properly mounted to the surgical device; and a localizer coupled to the one or more controllers and being configured to detect actual states of the trackable features in a coordinate system; and wherein the one or more controllers are configured to: determine the actual state of the tool center point in the coordinate system based on the actual states of the trackable features detected by the localizer and the predetermined state of the trackable features defined relative to the actual state of the tool center point; compare the actual state and expected state of the tool center point; and evaluate whether the tool is properly mounted to the surgical device based on comparing the actual state and expected state of the tool center point. 
     In another example, a protective packaging for a tool is provided, wherein the tool includes a working portion and a tool center point associated with the working portion, the protective packaging comprising: a distal section defining a cavity configured to retain the working portion; and the distal section comprising trackable features, wherein the trackable features have a predetermined state defined relative to a state of tool center point, and the trackable features are configured to be detectable by a localizer for enabling the localizer to locate the tool center point. 
     In another example, an assembly for a surgical procedure is provided, the assembly comprising: a tool including a working portion and a tool center point associated with the working portion; and a protective packaging that retains the working portion, and wherein the protective packaging comprises trackable features, wherein the trackable features have a predetermined state defined relative to the tool center point and the trackable features are configured to be detectable by a localizer for enabling the localizer to locate the tool center point. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a protective packaging for retaining a tool in accordance with one example. 
         FIG. 2  is a plan view of the protective packaging of  FIG. 1  further illustrating trackable features on the packaging and their relationship to a tool center point of the tool. 
         FIG. 3  is an example system comprising a navigation system utilized in conjunction with a surgical device, in this example, the end effector of a robotic manipulator which is configured to receive the tool retained by the packaging, and further illustrates relationships between components of the system that can be known or determinable by one or more controllers to determine the state of the tool center point of the tool. 
         FIG. 3A  is an expanded view of the packaging and tool from  FIG. 3  further illustrating the relationship between the trackable features and the tool center point. 
         FIG. 4  illustrates one example of surgical device and the one or more controllers wherein an expected tool center point of the tool known to the one or more controllers is illustrated in a hypothetical condition wherein the tool is properly installed to the surgical device. 
         FIG. 5  illustrates the surgical device of  FIG. 4  wherein the packaged tool is improperly installed to the surgical device, and wherein the one or more controllers compares the expected tool center point from  FIG. 4  to an actual state of the tool center point to determine an error condition. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are trackable protective packages for tools, and systems and methods for tracking the protective packaging for various purposes, such as to confirm installation of the tool to a surgical device. 
     A. Examples of Protective Packaging for Tools 
     Referring to  FIG. 1 , a non-limiting example of a protective packaging  22  is illustrated. The protective packaging  22  is specifically shaped to accommodate and retain a tool  24  and provides safe, sterile and secure handling of the tool  24  during storage, transport, and mounting of the tool  24  on a surgical device  28  (see  FIGS. 3 and 5 ). In view of the techniques described below, having the protective packaging  22  be utilized during or after mounting of the tool  24  on the surgical device  28  provides significant advantages. 
     The protective packaging  22  and its uses during tool  24  installation can be like those described in US Pat. App. Pub. No. 2018/0296297A1, entitled “Packaging Systems and Methods for Mounting A Tool on A Surgical Device”, the disclosure of which is hereby incorporated by reference in its entirety. However, the protective packaging  22  can have different configurations from the protective packaging  22  shown. 
     In one example, the tool  24  is a device that is configured to remove material from a target site, such as a bone of a patient, soft tissue, or the like. For these reasons, the tool  24  is likely to be a sharp object. The tool  24  can also be a passive object, i.e., a purely mechanical object having no actively energizable electrical components. Examples of tools  24  include, but are not limited to burs, drill bits, screw drivers, saws, and the like. 
     The tool  24  comprises a working portion W or energy applicator. The working portion W is a feature of the tool  24  that is configured to interact with and manipulate the target site. When the tool  24  is a bur, the working portion W is the bur head  26  rigidly coupled to a tool shaft  25  (as shown). When the tool  24  is a drill bit, the working portion W can be the threaded portion of the drill shaft or a distal tip of the drill bit. When the tool  24  is a saw, the working portion W can be a distal tip or teeth of the saw blade. For simplicity in description, the tool  24  described in the examples below is a bur and the working portion is the bur head  26 . However, various other tools  24  with different working portions W are fully contemplated to be utilized with the techniques described herein. 
     The surgical device  28  may be any apparatus configured to receive and operate the tool  24 . In other words, the surgical device  28  may provide actuation, control, power, etc., to the tool  24 . The surgical device  28  of  FIGS. 3-5  is a surgical robot R having an end effector configured to receive the tool  24 . In this example, the surgical device  28  can be the robot R and/or the end effector. Other example combinations of the tool  24  and the surgical device  28  are contemplated. For example, possible combinations may include: a saw or a blade configured to be received by a saw driver; a router, a curved bur, or a sleeve connector for a bur configured to be received by a handheld rotary instrument; electrodes configured to be received by a smoke evacuation pencil; a scalpel configured to be received by a scalpel handle; an ultrasonic tip configured to be received by an ultrasonic aspirator; and an endoscopic shaver or cutter configured to be received by an endo-handpiece. For any of the example above, the surgical device  28  can be a hand-held instrument configured to be supported (against the force of gravity) and manually moveable in space by the hand and arm of a user. It is to be understood that other surgical devices for receiving tools are contemplated. As will be described below, the tool  24  and/or surgical device  28  according to any configuration may be tracked by a navigation system. 
     In one example, the tool  24  includes a distal region  27  and an attachment portion  29 . The working portion W is at the distal region  27  of the tool  24  and the attachment portion  29  is the part of the tool  24  that installs to the surgical device  28 . In some instances, the attachment portion  29  is located a proximal region of the tool  24 , opposite the distal region  27 . At the distal region  27  is a distal end  30  and at the attachment region  29  is a proximal end  32  of the tool  24 . A length of the tool  24  can be defined between the distal end  30  and the proximal end  32 . If the tool  24  is symmetrical about an axis of rotation, a tool axis may be defined between the distal end  30  and the proximal end  32 . 
     In this example, the protective packaging  22  provides a casing that comprises a distal section  34  that has a cavity to retain the distal region  27  of the tool  24  to protect the operator and prevent contamination. The distal section  34  may comprise distal portions  36 ,  38  that collectively retain the tool  24 . The distal portions  36 ,  38  can be separate components or can be integrally formed as one component. The distal portions  36 ,  38  may be pivotably coupled to one another such that they can open and close, in a clamshell configuration. In such examples, the distal section  34  can be opened to enable removal of the tool  24  from the protective packaging  22  and closed to enable retention of the  24  in the protective packaging  22 . In other examples, the distal portions  36 ,  38  can be permanently coupled together, such as by using a high frequency weld, adhesive, integrally formed material, etc. In such examples, the protective packaging  22  can be configured to slide over and off the tool  24 . 
     In some examples, the protective packaging  22  can have only the distal section  34 . In other examples, such as that shown in  FIG. 1 , the protective packaging  22  can optionally include a proximal section  40  that couples to the distal section  34 . The proximal section  40  can be provided with a cavity to retain the proximal end of the tool  24 , such as the tool shaft  25 . The proximal section  40  can be pivotably coupled to the distal section  34  at a hinge  42 . This hinge  42  enables the proximal section  40  to be detached from the tool shaft  25  simultaneously while remaining hinged to the distal section  34 . This way, the tool shaft  25  can be exposed for installation while the proximal section  40  can provide shielding protection for the operator&#39;s hand. In other examples, the hinge may comprise a perforation  44  that enables the proximal section  40  to be detached completely from the distal section  34 . 
     Importantly, the protective packaging  22  provides a low dimensional tolerance and/or tight mechanical fit when retaining the tool  24 . Features may be designed into the tool  24  and/or the protective packaging  22  to achieve the fit. For example, a hole could be placed in a saw blade with a mating protrusion in the protective packaging  22 , or an undercut could of a drill shaft could be used to align with a protrusion in the protective packaging  22 . As will be described below, the tight tolerance securely retains the tool  24  while providing a known relationship between features of the protective packaging  22  (e.g., trackable features) and the tool  24 . In one example, the dimensional tolerance is less than 1 mm or even less than 0.1 mm. Any suitable casing of the protective packaging  22  is contemplated that protect the operator and prevent contamination while maintaining a tight mechanical retention of the tool  24 . Hence, the casing of the protective packing  22  is not limited to the examples described herein. 
     The protective packaging  22  may comprise, in part or entirely, material such as polyethylene terephthalate glycol-modified (PETG). Other suitable materials may include, without limitation, polymers such as polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS), epoxy and other resins, and malleable metals such as aluminum. The protective packaging  22  can be formed by thermoforming, injection molding, vacuum molding, blow molding, or other manufacturing processes. 
     Various different configurations of the protective packaging  22  are contemplated. For example, the protective packaging  22  can be hermetically sealed (against liquid and gas). The protective packaging  22  can be reusable (sterilizable) or disposable (single use). The protective packaging  22  can have features, such as texturized features, to enable the operator to easily grip the protective packaging  22  for tool  24  installation or to open and close the distal portions  36 ,  38 . The protective packaging  22  or any of its components can be adjustable in size or dimension, and can be elastic, flexible, or deformable. The protective packaging  22  can be tool  24  specific or generically usable for different tools. As will be described below, the protective packaging  22  can also have features that enable the protective packaging  22  to be detectable and/or to avoid being detectable. 
     The protective packaging  22  can be used for initial attachment of the tool  24  to the surgical device  28  or it can be used for re-attachment of the tool  24  during the surgical procedure. There may be a need to re-check the position of the tool  24  during the procedure or the tool  24  may be removed for a portion of the procedure and later re-installed. The protective packaging  22  can have any combination of the features described herein and can have configurations or features other than those described herein. 
     B. Trackable Features for the Protective Packaging 
     As shown in the non-limiting example of  FIGS. 1 and 2 , the protective packaging  22  can comprise one or more trackable features T. The trackable features T can be utilized to track the tool  24  when the tool  24  is retained by the protective packaging  22 . The trackable features T can also be utilized to track the protective packaging  22  when the tool  24  is not retained therein. In another example, described below, the trackable features T are utilized to determine whether or not the tool  24  is properly mounted/installed to the surgical device  28 . 
     The protective packaging  22  may comprise any number and any configuration of trackable features T. In this example, three trackable features T 1 -T 3  are provided with the protective packaging  22 . Having at least three trackable features T provides the ability to know the position and orientation of the protective packaging  22 . The trackable features T can be placed on or affixed to the protective packaging  22  utilizing any suitable technique. Alternatively, the trackable features T can be integrally formed on, in, or with the protective packaging  22 . For example, the trackable features T can be embedded within the material of the protective packaging  22 . The trackable features T can also be uniquely identifiable features integral to the protective packaging  22 , such as edges, protrusions, recesses, shapes or any of the components of the protective packaging  22  described herein. 
     The trackable features T can be passive or actively energized and can be of any appropriative type of detectable configuration. The trackable features T may be infrared trackable features. When infrared, the trackable features T can be retroreflective elements or LED emitters, for example. Alternatively or additionally, the trackable features T can be passive landmarks, patterns, and/or shapes that are uniquely identifiable. The trackable features T can also be configured with patterns, colors, gradients, and/or texturized materials. In other examples, the trackable features T can be passive or active magnetic or electro-magnetic elements, passive or active radio frequency elements, radio-opaque elements, ultrasound detectable elements, or any combination of the above-described configurations. 
     The trackable features T can be provided on the protective packaging  22  in any location, manner, or configuration. For example, the trackable features T can be positioned the first and/or second distal portions  36 ,  38 . The trackable features T can also be positioned on the proximal section  40 . In one example, the trackable features T are provided only on the distal section  34 , but not the proximal section  40 . This configuration is based on the practical consideration that the working portion W of the tool  24  will remain retained by the distal section  34  during tool  24  installation, whereas the proximal section  40  may be detached from the protective packaging  22  or otherwise pivoted relative to the distal section  34  prior to installation. Furthermore, the trackable features T can be positioned on one side or multiple sides of the protective packaging  22 , including any of the top, bottom, or left or right sides, as needed, to enable the trackable features T to be detectable. 
     In another example, each of the first and second distal portions  36 ,  38  comprises an exterior surface, which is exposed when the protective packaging  22  is closed. In this example, one or more trackable features T can be coupled to the exterior surface of at least one of the first and second distal portions  36 ,  38 . As such, the trackable features T can be readily visible when the protective packaging  22  is closed. 
     In yet another example, the trackable features T may comprise sub-components on different parts of the protective packaging  22 . For example, each of the first and second distal portions  36 ,  38  comprises an interior surface. The interior surfaces engage each other when the protective packaging  22  is closed. In this example, one or more trackable features T comprise a first component coupled to the interior surface of the first distal portion  36  and a second component coupled to the interior surface of the second distal portion  38 . The first and second components are positioned such that when the protective packaging  22  is closed, the first and second components engage or combine to form the trackable feature T. In other words, the trackable feature T may be functional when the protective packaging  22  is fully closed and non-functional when the protective packaging  22  is partially or entirely open. The first and second components can be electrical, magnetic, or layers of material (e.g., reflective material) that work together to form the trackable feature T when the protective packaging  22  is closed. The trackable features T can also extend through the material of the protective packaging  22  such that the trackable feature T is on both the exterior and interior surfaces of the protective packaging  22 . 
     The protective packaging  22  may comprise a material that is transparent to light. The transparent material can increase visibility and/or reduce retro-reflectivity of the protective packaging  22  to increase accuracy in detecting the trackable features T. When transparent, visible light penetration through the protective packaging  22  material may be greater than 75%, 90%, or 95%. The protective packaging  22  can also be equipped with surface properties or features to reduce retro-reflectivity. Examples of such properties or features include, but are not limited to, rough surfaces, dimpled surfaces, anti-reflective coating or film, or the like. 
     The trackable features T and the configuration of the protective packaging  22  can be different than the examples described above. 
     C. Example Navigation Systems 
     To implement tracking of the trackable features T, a navigation system  100  is provided, as shown in  FIG. 3 , for example. The navigation system  100  can be utilized in conjunction with the surgical device  28 . As shown in  FIG. 3 , for example, the surgical device  28  is the end effector of the robot R that is configured to receive the tool  24 . 
     The navigation system  100  is configured to track movement of various objects. Such objects include, for example, the protective packaging  22 , the robot R, the surgical device  28  and the anatomy of a patient. The navigation system  100  tracks these objects with respect to a (navigation) localizer coordinate system LCLZ. Coordinates in the localizer coordinate system LCLZ may be transformed to the robot (manipulator) coordinate system MNPL, and/or vice-versa, using transformation techniques described herein. 
     One example of the navigation system  100 , surgical robot, control techniques, and transformations associated therewith, which can be utilized with the techniques herein, is described in U.S. Pat. App. Pub. No. 2018/0168750A1 filed on Dec. 13, 2017, entitled, “Techniques for modifying tool operation in a surgical robotic system based on comparing actual and commanded states of the tool relative to a surgical site,” the entire disclosure of which is hereby incorporated by reference. 
     The navigation system  100  may include a cart assembly  102  that houses the one or more controllers  104 , such as a navigation computer, and/or other types of control units. The one or more controllers  104  may also be located in the surgical device  28  and/or a cart of the robot R. The one or more controllers  104  may be located in components or subsystems other than that shown in  FIG. 3  and may be implemented on any suitable device or devices in the system  100  other than the configuration shown. In one example, the controllers for the navigation system and the robot are two different controllers performing different operations, and can be configured, for example, as described in U.S. Pat. App. Pub. No. 2018/0168750A1. The one or more controllers  104  can comprise software and/or hardware configured to perform all the tasks described herein. Example of hardware may comprise processors, CPUs, microprocessors, integrated circuits, non-transitory memory, graphic processing units, hard drives, and input/output devices. 
     A navigation interface is in operative communication with the one or more controllers  104 . The navigation interface includes one or more displays  106 . The one or more controllers  104  is capable of displaying graphical (actual or virtual) representations of the relative states of the tracked objects to the operator using the one or more displays  106 . As will be described below, alerts, notifications, or error messages can also be represented on one or more of the displays  106 . 
     In addition to the trackable features T described with respect to the protective packaging  22 , the other objects tracked by the navigation system  100  include one or more trackers or trackable features. In one example, as shown, the trackers may include a tool tracker  108  attached to surgical device  28  (e.g., end effector), a robot tracker  109  attached to the base of the robot R (as shown) or to one or more links of the robot R, and target site trackers (not shown), which can be attached to a patient. Any one or more of the trackers may include active or passive trackable features, and may be used with any tracking modality described herein. 
     The navigation system  100  also includes a navigation localizer  110  (hereinafter “localizer”) that tracks a state of trackable features T on the protective packaging  22 , and other trackers or trackable features. As used herein, the state of an object includes, but is not limited to, data that defines the position and/or orientation of the tracked object or equivalents/derivatives of the position and/or orientation. For example, the state may be a pose of the object, and may include linear data, and/or angular velocity data, and the like. The localizer  110  provides the state of these tracked objects to the one or more controllers  104  to enable the one or more controllers  104  to make determinations based on such information. 
     In one example, as shown in  FIG. 3 , the localizer  110  is an optical localizer and includes a camera unit  112  with one or more optical sensors  114 . The localizer  110  can be an infrared based localizer suitable for detecting trackable features T that are configured with active or passive infrared elements. Although one embodiment of the navigation system  100  is shown in  FIG. 3 , the navigation system  100  may have any other suitable configuration for tracking the trackable features T. 
     Additionally, or alternatively, the localizer  110  can be a machine vision system, The machine vision system can comprise a camera that is configured to detect trackable features T that can include patterns, shapes, colors, textures, gradients and/or uniquely identifiable features provided by the protective packaging  22 . The machine vision system can employ various types of imaging and imaging processing modalities, such as 2D/3D visible light imaging, depth maps, pixel analysis, edge detection, pattern recognition, and the like. One example of a machine vision system that can be utilized is described in US Publication No. 2017/0143432A1, entitled, Systems and Methods for Establishing Virtual Constraint Boundaries,” the entire contents of which are incorporated by reference herein. 
     In another example, the navigation system  100  and/or localizer  110  are radio frequency (RF)-based. For example, the navigation system  100  may comprise an RF transceiver in communication with the one or more controllers  104 . The trackable features T of the protective packaging  22  may comprise RF emitters or transponders. The RF emitters or transponders may be passive or actively energized. The RF transceiver transmits an RF tracking signal and generates state signals to the one or more controllers  104  based on RF signals received from the RF emitters. The one or more controllers  104  may analyze the received RF signals to associate relative states thereto. The RF signals may be of any suitable frequency. The RF transceiver may be positioned at any suitable location to effectively track the objects using RF signals. Furthermore, the RF emitters or transponders may have any suitable structural configuration that may be much different than the trackers or trackable features as shown in the Figures. 
     The navigation system  100  and/or localizer  110  can also be electromagnetically based. For example, the navigation system  100  may comprise an EM transceiver coupled to the one or more controllers  104 . The trackable features T of the protective packaging  22  may comprise EM components, such as any suitable magnetic tracker, electro-magnetic tracker, inductive tracker, or the like. The trackable features T may be passive or actively energized. The EM transceiver generates an EM field and generates state signals to the one or more controllers  104  based upon EM signals received from the trackers. The one or more controllers  104  may analyze the received EM signals to associate relative states thereto. Again, such navigation system  100  embodiments may have structural configurations that are different than the navigation system  100  configuration as shown throughout the Figures. 
     In another example, the navigation system  100  and/or localizer  110  are ultrasound-based. For example, the navigation system  100  may comprise an ultrasound imaging device coupled to the one or more controllers  104 . The ultrasound imaging device images any of the aforementioned objects, e.g., the protective packaging  22  and/or trackable features T generate state signals to the one or more controllers  104  based on the ultrasound images. For example, the ultrasound imaging device may be a portable device whose position is tracked. The portable device can be positioned proximate to any object to track the object. The one or more controllers  104  may process the images in near real-time to determine states of the objects. The ultrasound imaging device may have any suitable configuration and may be different than the camera unit  112  as shown in  FIG. 3 . 
     The navigation system  100  and/or localizer  110  may be based on any combination of the tracking modalities above and may have any other suitable components or structure not specifically recited herein. Furthermore, any of the techniques, methods, and/or components described above with respect to the camera-based navigation system  100  shown throughout the Figures may be implemented or provided for any of the other embodiments of the navigation system  100  described herein. 
     D. Tool Center Point and Relationship to Protective Packaging 
     According to the techniques described herein, the trackable features T of the protective packaging  22  are utilized to track the tool  24  when the tool  24  is retained by the protective packaging  22 . More specifically, the navigation system  100  can track the trackable features T to determine whether or not the tool  24  is properly mounted/attached to the surgical device  28 . 
     To help facilitate this technique, the protective packaging  22  provides a low dimensional tolerance and tight mechanical fit when retaining the tool  24 . Furthermore, the protective packaging  22  is involved with the process of installing the tool  24  to the surgical device  28 . Therefore, tracking the protective packaging  22  to determine whether or not the tool  24  is properly mounted/attached to the surgical device  28  provides the advantages of reducing steps and reducing additional devices in the operating room. Furthermore, the tight tolerance provides measurements with a high degree of accuracy as compared with prior techniques. The tight tolerance provided by the protective packaging  22  enables the techniques herein to treat the protective packaging  22  as a virtual extension of the tool  24  geometry for calibration or verification purposes. By providing tracking features on the protective packaging  22 , permanent tracking features on the tool  24  (particularly near the working portion) can be avoided. Avoiding permanent tracking features on the tool  24  is advantageous since permanent tracking features on a tool  24  can interfere with tool  24  operation or with the surgical site and cannot be located proximate enough to working portion of the tool  24  since the working portion is utilized to manipulate the anatomy. On the other hand, the protective packaging  22  is installed on the working portion, and hence, maximizes the calibration and verification measurement capability to the distal-most portion of the tool  24 . Furthermore, the methods described herein provide a seamless user experience, as accuracy checks can be done without adding external components or steps. 
     Referring to  FIG. 2 , the tool  24  comprises a tool center point (TCP), which in one embodiment, is a predetermined reference point defined at the working portion W or relative to the working portion W. In one embodiment, the TCP is assumed to be located at the center of a spherical of the tool  24  such that only one point is tracked. The TCP may relate to a bur having a specified diameter. Often, the TCP is defined at a location that is at a center of the working portion W. For example, as shown in  FIG. 2 , the TCP is located at the spherical center of the bur. However, this may not always be the case. For example, the TCP of a drill bit can be a point in the cylindrical center of the drill, but located anywhere along the tool shaft  25 . Similarly, for a saw blade, the TCP can be located anywhere on the saw blade. The TCP can also be arbitrarily defined somewhere with respect to the working portion W. Therefore, the term “center” is not limited to the geometrical center of the working portion W. The TCP may be defined according to various manners depending on the configuration of the working portion W. 
     Furthermore, the TCP can be a physical point on the working portion W or the TCP can be a virtual point. In either instance, the one or more controllers  104  is configured to store the predetermined TCP state relative to known geometry for the specified tool  24 . Aside from the techniques described herein for confirming installation of the tool  24 , the TCP can also be utilized by the one or more controllers  104  to facilitate control of the tool  24  and/or surgical device  28 . For example, such control can be movement of the tool  24  relative to virtual boundaries or tool paths. Examples of TCPs and uses thereof in controlling surgical devices can be like those described in US Pat. App. Pub. No. 2018/0168750A1, entitled “Techniques for modifying tool operation in a surgical robotic system based on comparing actual and commanded states of the tool relative to a surgical site,” the entire contents of which are hereby incorporated by reference. 
     In instances where the tool  24  is not directly tracked by the navigation system  100 , the state of the working portion W relative to the surgical device  28  or relative to the navigation system  100  may not be known. Advantageously, when the tool  24  is retained by the protective packaging  22 , the actual state of the TCP can be determined since the protective packaging  22  has trackable features T. As used herein, the “actual” state of the TCP is the real position and/or orientation of the TCP in physical 3D space or in a global coordinate system. In one example, this global coordinate system is the localizer coordinate system LCLZ. To facilitate this determination, the trackable features T are specifically positioned on the protective packaging  22  with a predetermined state defined relative to the actual state of the TCP. The one or more controllers  104  is configured to store these predetermined states of the trackable features T relative to the actual state of the TCP for further evaluations, as will be described below. 
     Prior to tracking, the actual state of the TCP can be assumed in the correct state relative to the trackable features T based on the understanding that the tool  24  is properly retained by the protective packaging  22 . Mainly, the various features of the protective packaging  22  described above (e.g., tight mechanical fit) help to ensure that the tool  24  is properly retained relative to the protective packaging  22  so as to validate this assumption. 
     As shown in the example in  FIG. 2 , the trackable features T 1 -T 3  (in this case, passive markers) and the actual state of the TCP can be defined in a common coordinate system (e.g., the coordinate system of the protective packaging  22 ). In this example, the actual state of the TCP can be considered the origin of the coordinate system, and the center of each trackable feature T is utilized for the coordinate measurements. However, it is not necessary to define the actual state of the TCP at the origin of the coordinate system nor to utilize the center of each trackable feature T for measurement. 
     In  FIG. 2 , an X-axis and Y-axis define the coordinate system, where X and Y are distances relative to the origin TCP. There may also be Z-axis coordinates (in and out of the page of  FIG. 2 ) that can be considered in this coordinate system. Z-axis coordinates would be appropriate if any of the trackable features T are defined on a different plane relative to the actual state of the TCP or relative to each other. For simplicity in description and illustration, the Z-axis coordinates are omitted on the assumption that the trackable features T are coplanar with the actual state of the TCP. However, the manner in which the Z-axis coordinates are determined can be like that described herein relative to the X and Y-axis coordinates. 
     Here, trackable feature T 1  is defined at −X 1 , Y 1  relative to the actual state of the TCP, trackable feature T 2  is defined at −X 1 , −Y 3  relative to the actual state of the TCP, and trackable feature T 3  is defined at X 1 , Y 2 , relative to the actual state of the TCP. The coordinate measurements and trackable feature T placement relative to the actual state of the TCP in  FIG. 2  is only one example. Of course, the trackable features T can have other predetermined states relative to the actual state of the TCP depending on factors such as the nature of the TCP, the types and positions of the trackable features T, and the structure of the protective packaging  22 , etc. 
     E. Techniques for Evaluating Tool Installation with Tracked Packaging 
     Referring back to  FIG. 3 , the navigation system  100  is shown with the tool  24  coupled to the surgical device  28 . The operator installs the tool  24  to the surgical device  28  by holding the protective packaging  22 . In this example, it is assumed that an attempt was made to install the tool  24  to the surgical device  28 , however, the operator may not be aware whether the tool  24  is properly installed. 
     As can be understood from the example of  FIG. 2 , the state of the actual TCP is known relative to the states of the trackable features T. As will be described below, the trackable features T of the protective packaging  22  and this known relationship are utilized by the navigation system  100  and one or more controllers  104  for determining whether the tool  24  is properly mounted/installed to the surgical device  28 . 
     To facilitate this determination, the navigation system  100  is shown with various transforms (T) for determining the actual state of the TCP in a global coordinate system, e.g. LCLZ. The transform (T), when calculated, gives the state (position and/or orientation) of a first component in its respective coordinate system relative to the state of a second component in its respective coordinate system. The one or more controllers  104  calculates/obtains and combines a plurality of transforms (T) from the various components of the system, e.g., for purposes such as to validate installation of the tool  24  and/or to control the surgical device  28  or robot R when the tool  24  is installed. The transforms (T) are computational determinations but are represented in  FIG. 3  by arrows between the subject components for illustrative purposes. The directionality of the arrow head is not intended to limit the direction of the transform. In other words, the transform (T) can give the state of one component with respect to the other, or vice versa. 
     In one embodiment, each transform (T) is specified as a transformation matrix, such as a 4×4 homogenous transformation matrix. The transformation matrix, for example, includes three unit vectors representing orientation, specifying the axes (X, Y, Z) from a first coordinate system expressed in coordinates of a second coordinate system (forming a rotation matrix), and one vector (position vector) representing position using the origin from the first coordinate system expressed in coordinates of the second coordinate system. 
     Example systems and methods for obtaining and computing transforms of the various components of the system is explained in U.S. Pat. No. 9,119,655, entitled, “Surgical Manipulator Capable of Controlling a Surgical Instrument in Multiple Modes,” and U.S. Pat. App. Pub. No. 2018/0168750A1 filed on Dec. 13, 2017, entitled, “Techniques for modifying tool operation in a surgical robotic system based on comparing actual and commanded states of the tool relative to a surgical site,” the entire disclosures of which are hereby incorporated by reference. 
     As shown in  FIG. 3 , the transforms include a first transform (T 1 ) between the localizer  110  and trackable features T of the protective packaging  22  and a second transform (T 2 ) (best shown in  FIG. 3A ) between the trackable features T and the actual state of the TCP. Other transforms that may be utilized include a third transform (T 3 ) between the localizer  110  and the surgical device  28  tracker  108 , a fourth transform (T 4 ) between the surgical device  28  tracker  108  and a reference point on the surgical device  28 , a fifth transform (T 5 ) between the actual state of the TCP and the reference point on the surgical device  28 , and/or a sixth transform (T 6 ) between the reference point on the surgical device  28  and a base of the robot (R). 
     Transforms (T 1 ) and (T 3 ) are obtained using tracking data from the localizer  110 . In other words, the localizer  110  tracks the state of the trackable features T of the protective packaging  22  and the state of the surgical device  28  tracker  108  relative to the LCLZ coordinate system. Transform (T 2 ) is obtained based on the known relationship between the trackable features T of the protective packaging  22  and the actual state of the TCP of the tool  24  retained by the protective packaging  22 , as described in the prior section. Transform (T 4 ) is obtained based on a known relationship between the surgical device  28  tracker  108  and the reference point on the surgical device  28 . Transform (T 5 ) is obtained based on a known relationship between an expected state of the TCP (i.e., the state of the TCP when the tool  24  is installed properly, which will be described further below) and the reference point on the surgical device  28 . Transform (T 6 ) can be determined based on kinematic data of the robot (R) stored by the one or more controllers  104  without intervention from the navigation system  100 . Alternatively or additionally, transform (T 7 ) can be obtained by localizer  110  determining the relationship between the surgical device  28  tracker  108  and the tracker  109  at the base of the robot R. Not all of these transforms (T) may be utilized in every instance, and these transforms (T) can be utilized in various combinations. 
     Any known relationship data (e.g., for transforms T 2 , T 4  or T 5 ) is stored by the one or more controllers  104  and may be fixed (constant or static) or variable. In embodiments where the known relationship data is fixed, the known relationship data may be derived from calibration information relating to the respective components (e.g., the surgical device  28 , the surgical device  28  tracker  108 , and the expected state of the TCP). For example, the calibration information may be obtained at a manufacturing/assembly stage, e.g., using coordinate measuring machine (CMM) measurements, etc. The known relationship data may be obtained using any suitable method, such as reading the known relationship data from a computer-readable medium, an RFID tag, a barcode scanner, or the like. The known relationship data may be imported into system  100  at any suitable moment such that the known relationship data is readily accessible by the one or more controllers  104 . In embodiments where the known relationship data is variable, the known relationship data may be measured or computed using any ancillary measurement system or components, such as additional sensors, trackers, encoders, or the like. The known relationship data may also be acquired after mounting the surgical device  28  tracker  108  to the surgical device  28  in preparation for a procedure by using any suitable technique or calibration method. 
     With reference to  FIGS. 4 and 5 , the one or more controllers  104  is configured to evaluate the information described above to determine whether the tool  24  is properly mounted to the surgical device  28 . For example, the one or more controllers  104  can determine whether or not the TCP is in the proper position and take action in response. 
     In  FIG. 4 , the one or more controllers  104  is configured to store the expected state of the TCP based on an expected condition in which the tool  24 ′ is properly mounted to the surgical device  28 . The expected state of the TCP is a virtual state (e.g., point) stored in one or more controllers  104  memory rather than a physical state on the tool  24  itself. For this reason, a dotted representation of the tool  24 ′ is shown in  FIG. 4  to represent the expected state of the TCP during an assumed proper installation. Furthermore, in  FIG. 4 , a proper installation line  120  is shown within the tool receiving portion of the surgical device  28  to illustrate one example of where a proximal end  32  of the tool  24  should be relative to the surgical device  28  when the tool  24 ′ is properly installed. In this illustration, the hypothetical tool  24 ′ is fully seated within the surgical device  28  (and hence properly installed) such that the proximal end  32  of the tool  24 ′ aligns with line  120 . 
     This installation representation is for simplicity in description and illustration, and tool  24 ′ installation schemes will vary depending on the type of tool being installed and the configuration of the surgical device  28 . Hence, the use of an “installation line”  120  is not intended to limit the nature of proper installation conditions. Indeed, the proper installation between the tool  24  and the surgical device  28  may be defined by any suitable number of reference datum having any complexity designated by the respective installation scheme. Additionally, or alternatively, proper installation may be defined by any suitable physical parameter measured between the tool  24  and the surgical device  28 , wherein the physical parameter can be correlated with, compared to, or otherwise associated to physical parameters derivable from the trackable features of the packaging  22  and the TCP. Such physical parameters may include, but not limited to: position, magnitude of displacement, distance, orientation, linear motion or velocity, angular motion or velocity, inertial parameters, force parameters, displacement parameters, pressure parameters, torque parameters. Hence, instead of comparing the expected state of the TCP to the actual state of TCP based on static position, the techniques may be utilized to compare an expected motion of the TCP during expected proper installation to actual motion of the TCP during actual installation. Accordingly, the term “state” is not intended to be limited to a static moment in time, but may encompass a period of time. Hence, the term “state” can be static or dynamic. 
     Furthermore, the installation scheme between the tool  24  and the surgical device  28  may include any suitable sensing devices, including but not limited to, direct (DC) electrical connection sensors, proximity sensors, hall effect sensors, electromagnetic sensors, radio frequency sensors, inductive sensors, capacitive sensors, and the like. These sensors are not intended to replace the techniques described herein, but rather can optionally be utilized in conjunction with the techniques described herein, for purposes such as tool identification, coarse tool installation, or tool presence detection. 
     The expected state of the TCP can be locally derived from the described known relationship data for transform T 5 , which can obtained using any manner described above. Additionally, or alternatively, the expected state of the TCP can be based on separate known relationship data obtained about the relationship between the expected state of the TCP and any other portion of the surgical device  28 , such as the portion that receives the tool  24 . For any given pose of the robot R or state of the surgical device  28 , the one or more controllers  104  can determine the expected state of the TCP based on combining the transforms (T) described above. For example, the expected state of the TCP can be determined by combining any one of the following combinations: (T 3 +T 4 +T 5 ), (T 5 +T 6 ), (T 5 +T 6 +T 7 ), etc. 
     If/when the tool  24  is properly installed, the expected TCP and the actual TCP states should be identical. Otherwise, if the tool  24  is improperly installed, the expected TCP and the actual TCP states will be different. Additionally, the trackable features may be different for different tools  24 . This will allow the system to further identify the tool  24  being used and/or confirm the correct tool is used. 
       FIG. 5  illustrates the actual installation condition of the tool  24  relative to the surgical device  28 . In this situation, the tool  24  is improperly mounted to the surgical device. This error condition is illustrated by distance d between the proximal end  32  of the tool  24  and the proper installation line  120 . In other words, the tool  24  is not fully seated in the surgical device  28 . The distance d can be difficult to detect to the human eye, e.g., 1 mm or less. Hence, the tool  24  is not properly installed, but may appear so to the operator. Although the error condition is represented by distance d in this example, it is possible that the error condition can take other forms depending on the nature of the tool  24 , the surgical device  28 , and/or manner of installation. For example, the error condition can be an identification of an incorrect tool, improper rotation, linear position, orientation, damage to the tool, or any combination thereof. Regardless of the nature of the error condition, the techniques described herein are configured to detect the error. 
     Since the tool  24  is improperly installed in  FIG. 5 , the state of the actual TCP differs from the state of the expected TCP. In this example, the error condition (distance d) at the proximal end  32  of the tool  24  causes a corresponding gap d between the actual TCP and expected TCP states. Of course, other error conditions are possible. For example, a measured distance of the tool  24  that is offset with the tool insertion axis could indicate the tool  24  is damaged or is the incorrect tool. 
     The one or more controllers  104  can make this determination by obtaining the state of the actual TCP using the transforms (T) described above. Regardless of the pose of the robot R or the state of the surgical device  28 , the one or more controllers  104  can determine the actual TCP state based on combining transformations (T 1 +T 2 ). In other words, the actual state of the TCP is known to the one or more controllers  104  by the tracked state of the trackable features T of the protective packaging  22  and the predetermined states of the trackable features (T) defined relative to the actual state of the TCP. The one or more controllers  104  can arrive at the actual and expected TCP states by combining other combinations of transformations other than those specifically described. 
     Knowing the states of the actual and expected TCPs, the one or more controllers  104  can compare them using any suitable method, such as comparing position/orientation matrix data from the transforms, etc. In certain examples, different transformation combinations can be compared to validate comparison results. For example, the state of the actual TCP can be validated in the LCLZ coordinate system by comparing the tracking data of the surgical device  28  tracker  108  (transform T 3 ) with the tracking data of the trackable features T on the protective packaging  22  (transform T 1 ). 
     If the one or more controllers  104  determines that the states of the actual and expected TCPs, are different, the one or more controllers  104  may instruct generation of a notification or alert to inform the operator of the error condition. The alert or notification can be visual and provided on the display  106 , as shown in  FIG. 3 . The alert can also be audible or haptic. Based on the nature of the error condition determined by the one or more controllers  104 , the one or more controllers  104  can issue specific instructions about how to resolve the error condition given the circumstance. For example, the one or more controllers  104  may generate a notification instructing the operator to “fully insert the tool shaft” or “rotate the tool shaft 180 degrees clockwise”. At any point, the one or more controllers  104  can re-assess the states of the actual and expected TCPs and inform the operator that the tool  24  is properly installed if the results of the comparison are favorable. 
     If the expected TCP state is different from the actual TCP state, the system may propose a decision process. For example the system may ask the user to confirm the correct tool is used, the system may suggest the user replace a damaged tool, and/or the user could instruct the system to accept the position of the actual state of the TCP and use the location for the remainder of the surgical procedure. 
     In certain instances, the one or more controllers  104  can be configured with a tolerance or threshold or range of error or acceptance when evaluating the differences between the states of the actual and expected TCPs. For instance, the one or more controllers  104  can have a tolerance of +/−0.1 mm such that if the states of the actual and expected TCPs are off by less than 0.1 mm, the one or more controllers  104  can nevertheless determine that the tool  24  is properly installed. The tolerance may be different from the value given, depending on many factors, such as the mechanical stack-up of components of the system, the nature of the installation, the accuracy of the localizer  110 , or the like. If the actual state of the TCP falls within acceptable range of the expected state of the TCP tolerance, the state of the actual TCP can be stored by the one or more controllers  104  as the calibrated TCP state that will be used for controlling the surgical device  28 . 
     Several embodiments have been discussed in the foregoing description. However, the embodiments discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described.