Patent Publication Number: US-11638999-B2

Title: Synthetic representation of a surgical robot

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/161,204 (filed Oct. 16, 2018) which is a continuation of U.S. patent application Ser. No. 15/629,533 (filed Jun. 21, 2017) which is a division of U.S. patent application Ser. No. 12/415,354 (filed Mar. 31, 2009) which is a continuation in part of U.S. patent application Ser. No. 11/478,531 (filed Jun. 29, 2006) and a continuation in part of U.S. patent application Ser. No. 12/163,087 (filed Jun. 27, 2008), all of which are incorporate herein by reference in their entireties. 
    
    
     BACKGROUND 
     Minimally invasive surgeries performed by robotic surgical systems are known and commonly used in remote or in other environments where it is advantageous for a human not to perform surgery. One example of such a telerobotic surgical system is the minimally invasive robotic surgery system described in commonly owned U.S. Pat. No. 7,155,315. The da Vinci® Surgical Systems manufactured by Intuitive Surgical, Inc. of Sunnyvale, Calif. are illustrative implementations of minimally invasive robotic surgical systems (e.g., teleoperated; telesurgical). 
     A common form of minimally invasive surgery is endoscopy. Endoscopic surgical instruments in minimally invasive medical techniques generally include an endoscope for viewing the surgical field, and working tools that include end effectors. Typical surgical end effectors include clamps, graspers, scissors, staplers, or needle holders, as examples. The working tools are similar to those used in conventional (open) surgery, except that the end effector of each tool is supported on the end of, for example, an approximately 12-inch-long extension tube. 
     To manipulate end effectors, a human operator, typically a surgeon, manipulates or otherwise commands a locally-provided master manipulator. Commands from the master manipulator are translated as appropriate and sent to a remotely-deployed slave manipulator. The slave manipulator then manipulates the end effectors according to the operator&#39;s commands. 
     Force feedback may be included in minimally invasive robotic surgical systems. To provide such feedback, the remote slave manipulators typically provide force information to the master manipulator, and that force information is utilized to provide force feedback to the surgeon so that the surgeon is given the perception of feeling forces acting on a slave manipulator. In some force feedback implementations, haptic feedback may provide an artificial feel to the surgeon of tissue reactive forces on a working tool and its end effector. 
     Often, the master controls, which are typically located at a surgeon console, will include a clutch or other device for releasing one of the work tools at the patient site. This feature may be used, for example, in a system where there are more than two working tools. In such a system, the surgeon may release control of one working tool by one master and establish control over another working tool with that master. 
     The surgeon typically views an image of only the distal ends of the working tools that are within the endoscope&#39;s field of view. The surgeon cannot see portions of a tool, or an entire tool, that is outside the field of view. Accordingly, the surgeon cannot see if two or more tools are interfering with each other outside the field of view. Further, since the endoscope may be manipulated to be at various positions and orientations with reference to a surgical site and to the surgeon&#39;s body frame of reference, the surgeon may become confused about the general location of the tools. Consequently, the surgeon may not understand how to best move the master manipulators to avoid an inter-tool interference or to reorient one or more tools with reference to the surgical site. 
     SUMMARY 
     The following presents a simplified summary of some aspects and embodiments of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some aspects and embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented later. 
     In an embodiment, a robotic surgical system is provided. The system includes a robot including a linkage supporting at least one tool for performing surgery on a patient; a kinematic component coupled to the robot so as to obtain joint state information from the linkage; a display; and a first component coupling the display with the kinematic component so as to display a synthetic representation of the robot including a graphical representation of at least a portion of the linkage based upon linkage structure data regarding the linkage; and the joint state information. 
     In another embodiment, a robotic surgical system is provided. The system includes a robot including an image capture device having a field of view and a linkage supporting at least one tool for performing surgery on a patient; a kinematic component coupled to the linkage so as to obtain joint states information regarding the linkage; data regarding structure of the first linkage and said at least one tool; and a collision detection component coupled to the data and to the kinematic component so as to generate a warning. 
     In still another embodiment, a method of controlling a position of a tool in a robotic system is provided. The method includes displaying a first image on a display, the first image comprising a video feed of a tool or linkage of a robot within a field of view; displaying a second image on the display, the second image representing a three dimensional model of the tool or linkage, with the second image of the three dimensional model aligned with first image of the tool or linkage; and moving an input device with reference to the first and second images on the display so as to control movement of the tool or linkage. 
     In yet still another embodiment, a method of providing a range of motion of a tool of a robotic system is provided. The method includes displaying a first image representing a position of the tool; and superimposing on the first image a second image representing a limit of motion of the tool. 
     In yet another embodiment, a robotic system is provided. The method includes maintaining information about a position of a tool of a robotic system; and generating a signal as a result of the tool being within a threshold distance from a limit of motion of the tool. 
     In another embodiment, a robotic surgical system is provided. The system includes a robot including a linkage supporting at least one tool for performing surgery on a patient; an image capture device having a field of view encompassing the tool; a kinematic component coupled to the robot so as to obtain joint state information from the linkage; a display coupled to the image capture device to display the field of view; and a first component coupling the display with the kinematic component so as to display information on the tool represented in the field of view, the position of the information being based upon linkage structure data regarding the linkage; and the joint state information. 
     In still another embodiment, a method in a robotic system is provided. The method includes displaying a first image comprising a video feed of a tool supported by a robot within a field of view; and displaying a synthetic three-dimensional representation of the robot including the tool. 
     In another embodiment, a method in a robotic system is provided. The method includes displaying a first image comprising a video feed of a tool supported by a robot within a field of view, the first image consisting of a first portion of the robot; and displaying a synthetic three-dimensional representation of the robot including the tool, with the synthetic three-dimensional representation comprising a second portion of the robot that is greater than the first portion. 
     In yet another embodiment, a method is provided in a robotic system, the method including displaying a first image comprising a video feed of a tool supported by a robot within a field of view, the first image consisting of a first portion of the robot viewed from a first direction; and displaying a synthetic three-dimensional representation of the robot including the tool, with the synthetic three-dimensional representation viewed from a second direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a top view of an operating room which includes a minimally invasive telesurgical system; 
         FIG.  2    is front view of a patient cart for the minimally invasive telesurgical system of  FIG.  1   ; 
         FIG.  3    is a block diagram representing components of the minimally invasive telesurgical system of  FIG.  1   ; 
         FIG.  4    is a block diagram representing components for a computer for use in the minimally invasive telesurgical system of  FIG.  1   ; 
         FIG.  5    is a side perspective view of a master controller; 
         FIG.  6    is a view of a synthetic image of a robot; 
         FIG.  7    is a flowchart representing a process for updating a rendering of a synthetic image; 
         FIG.  8    is a view provided by a display that provides both a field of view for an endoscope and a synthetic image of a robot supporting the endoscope; 
         FIG.  9    shows a tile window displaying an alternate angle for viewing a portion of the synthetic image of a robot; 
         FIG.  10    shows a field of view in which two tools are colliding; 
         FIG.  11    is a flowchart showing a process for providing collision information; 
         FIG.  12    is a flow chart representing a process for lost tool recovery; 
         FIG.  13    shows a field of view projected over a window tile that includes a synthetic image of a robot; and 
         FIG.  14    is a flow chart representing a process for displaying information utilizing a modeling component. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, various aspects and embodiments of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details. Furthermore, well-known features may be omitted from this description or simplified in order not to obscure the embodiment being described. 
     Referring now to the drawings, in which like reference numerals represent like parts throughout several views,  FIG.  1    shows a minimally invasive telesurgical system  20  having an operator station or surgeon console  30  in accordance with an embodiment. The surgeon console  30  includes a viewer  32  where an image of a surgical site is displayed to a surgeon S. As is known, a support (not shown) is provided on which the surgeon S can rest his or her forearms while gripping two master controls  700  ( FIG.  5   ), one in each hand. More controls may be provided if more end effectors are available, but typically a surgeon manipulates only two controls at a time and, if multiple tools are used, the surgeon releases one tool with a master control  700  and grasps another with same master control. When using the surgeon console  30 , the surgeon S typically sits in a chair in front of the surgeon console, positions his or her eyes in front of the viewer  32 , and grips the master controls  700 , one in each hand, while resting his or her forearms on the support. 
     A patient side cart  40  of the telesurgical system  20  is positioned adjacent to a patient P. In use, the patient side cart  40  is positioned close to the patient P requiring surgery. The patient side cart  40  typically is stationary during a surgical procedure, and includes wheels or castors to render it mobile. The surgeon console  30  is typically positioned remote from the patient side cart  40 , and it may be separated from the patient side cart by a great distance—even miles away—but will typically be used within the same operating room as the patient side cart. 
     The patient side cart  40 , shown in more detail in  FIG.  2   , typically includes two or more robotic arm assemblies. In the embodiment shown in  FIG.  2   , the patient side cart  40  includes four robotic arm assemblies  42 ,  44 ,  46 ,  48 , but more or less may be provided. Each robotic arm assembly  42 ,  44 ,  46 ,  48  is normally operatively connected to one of the master controls of the surgeon console  30 . Thus, movement of the manipulator portion of the robotic arm assemblies  44 ,  46   48  is controlled by manipulation of the master controls. 
     One of the robotic arm assemblies, indicated by the reference numeral  42 , is arranged to hold an image capture device  50 , e.g., an endoscope, or the like. The endoscope or image capture device  50  includes a viewing end  56  at a remote end of an elongated shaft  54 . The elongated shaft  54  permits the viewing end  56  to be inserted through a surgery entry port of the patient P. The image capture device  50  is operatively connected to the viewer  32  of the surgeon console  30  to display an image captured at its viewing end  56 . 
     Each of the other robotic arm assemblies  44 ,  46 ,  48  is a linkage that supports a removable surgical instrument or tool  60 ,  62 ,  64 , respectively. The tools  60 ,  62 ,  64  of the robotic arm assemblies  44 ,  46 ,  48  include end effectors  66 ,  68 ,  70 , respectively. The end effectors  66 ,  68 ,  70  are mounted on wrist members which are mounted on distal ends of elongated shafts of the tools, as is known in the art. The tools  60 ,  62 ,  64  have elongated shafts to permit the end effectors  66 ,  68 ,  70  to be inserted through surgical entry ports of the patient P. Movement of the end effectors  66 ,  68 ,  70  relative to the ends of the shafts of the tools  60 ,  62 ,  64  is controlled by the master controls of the surgeon console  30 . 
     The depicted telesurgical system  20  includes a vision cart  80 , which contains equipment associated with the image capture device. In another embodiment, the vision cart  80  can be combined with other equipment that includes most of the computer equipment or other controls (the “core” data processing equipment) for operating the telesurgical system  20 . As an example, signals sent by the master controllers of the surgeon console  30  may be sent to the vision/core cart  80 , which in turn may interpret the signals and generate commands for the end effectors  66 ,  68 ,  70  and/or robotic arm assemblies  44 ,  46 ,  48 . In addition, video sent from the image capture device  50  to the viewer  34  may be processed by, or simply transferred by, the vision cart  80 . 
       FIG.  3    is a diagrammatic representation of the telesurgical system  20 . As can be seen, the system includes the surgeon console  30 , the patient side cart  40 , and the vision cart  80 . In addition, in accordance with an embodiment, an additional computer  82  and display  84  are provided. These components may be incorporated in one or more of the surgeon console  30 , the patient side cart  40 , and/or the vision cart  80 . For example, the features of the computer  82  may be incorporated into the vision cart  80 . In addition, the features of the display  84  may be incorporated into the surgeon console  30 , for example, in the viewer  32 , or maybe provided by a completely separate display at the surgeon console or on another location. In addition, in accordance with an embodiment, the computer  82  may generate information that may be utilized without a display, such as the display  84 . 
     Although described as a “computer,” the computer  82  may be a component of a computer system or any other software or hardware that is capable of performing the functions described herein. Moreover, as described above, functions and features of the computer  82  may be distributed over several devices or software components. Thus, the computer  82  shown in the drawings is for the convenience of discussion, and it may be replaced by a controller or its functions may be provided by one or more other components. 
       FIG.  4    shows components of the computer  82  in accordance with an embodiment. A positional component is included in or is otherwise associated with the computer  82 . The positional component provides information about a position of an end effector, such as one of the end effectors  66 ,  68 ,  70 . In the embodiment shown in the drawings, a tool tracking component  90  is used for the positional component and provides information about a position of an end effector, such as the end effectors  66 ,  68 ,  70 . As used herein, “position” means at least one of the location and/or the orientation of the end effector. A variety of different technologies may be used to provide information about a position of an end effector, and such technologies may or may not be considered tool tracking devices. In a simple embodiment, the positional component utilizes video feed from the image capture device  50  to provide information about the position of an end effector, but other information may be used instead of, or in addition to, this visual information, including sensor information, kinematic information, any combination of these, or additional information that may provide the position and/or orientation of the end effectors  66 ,  68 ,  70 . Examples of systems that may be used for the tool tracking component  90  are disclosed in, U.S. Pat. No. 5,950,629 (filed Apr. 28, 1994), U.S. Pat. No. 6,468,265 (filed Nov. 9, 1999), U.S. Pat. App. Pub. No. US 2006/0258938 A1 (filed May 16, 2005), and U.S. Pat. App. Pub. No. US 2008/0004603 A1 (filed Jun. 29, 2006). In accordance with an embodiment, the tool tracking component  90  utilizes the systems and methods described in commonly owned U.S. Pat. App. No. 61/204,084 (filed Dec. 31, 2008). In general, the positional component maintains information about the actual position and orientation of end effectors. This information is updated depending upon when the information is available, and may be, for example, asynchronous information. 
     The kinematic component  92  is generally any device that estimates a position, herein a “kinematic position,” of an end effector utilizing information available through the telesurgical system  20 . In an embodiment, the kinematic component  92  utilizes kinematic position information from joint states of a linkage to the end effector. For example, the kinematic component  92  may utilize the master/slave architecture for the telesurgical system  20  to calculate intended Cartesian positions of the end effectors  66 ,  68 ,  70  based upon encoder signals for the joints in the linkage for each of the tools  60 ,  62 ,  64 . As examples, the kinematic component may utilize slave encoders  102  and/or master manipulator encoders to estimate the position of tool. An example of system utilizing an embodiment of a kinematic component is described in U.S. Pat. No. 7,155,315, which is incorporated herein by reference, although others may be utilized. Kinematic position information for the end effector or any portion of the linkage and/or tool may also be provided in other ways, such as the use of optical fiber shape sensing, sensing the positions of components (e.g., electromagnetic components) embedded at various places along the linkage, tool, or end effector, various video tool tracking methods, etc. 
     In the embodiment shown in the drawings, an error correction component  94  is provided. In general, the error correction component calculates a difference between a location and/or orientation of a tool as provided by the tool tracking component  90  compared to the location and/or orientation of the tool as provided by the kinematic component  92 . Because of the large number of joints and movable parts, current kinematics measurement typically does not provide exact information for the location of a surgical end effector in space. A system with sufficient rigidity and sensing could theoretically provide near-exact kinetic information. In current minimally invasive robotic surgery systems, however, often the kinematic information may be inaccurate by up to an inch in any direction when taken in space. Thus, in accordance with an embodiment, an offset may be generated by the error correction component  94 . This offset provides information regarding the difference between the kinematic information provided by the kinematic component and the actual position information provided by the tool tracking component. Utilizing the offset, the kinematic information and the actual position information may be registered to the same location and/or orientation. 
     In accordance with an embodiment, a modeling component  108  is provided for generating a synthetic image  120  ( FIG.  6   ) of a patient side cart, such as the patient side cart  40 , or any portion thereof. In the embodiment shown in the drawings, the synthetic image  120  is of a different patient side cart configuration than the patient side cart  40  (an illustrative model of a da Vinci® Surgical System Model IS2000 patient side cart with three arms is shown), but the basic components of the two patient side carts are the same, except that the patient side cart  40  includes an additional robotic arm assembly and tool. In accordance with an embodiment, the synthetic image  120  may be displayed on the display  84  or the viewer  32 . To this end, modeling data  104  ( FIG.  3   ) may be provided that is associated with the vision cart  80  and/or the computer  82 . The modeling data  104  may be, for example, a two-dimensional (2-D) or three-dimensional (3-D) representation, such as an image, of the patient side cart  40 , or any portion thereof. In an embodiment, such a representation is a 3-D model of the patient side cart  40 , or any portion thereof, and thus may represent an actual solid model of the patient side cart  40 , or any portion thereof. The modeling data  104  may be, for example, CAD data or other 3-D solid model data representing components of the patient side cart  40 . In an embodiment, the 3-D model is manipulatable at each joint of the patient side cart  40 , so that movements of the patient side cart may be mimicked by the synthetic image  120  of the patient side cart  40 . The modeling data may represent the entire patient side cart or any portion thereof, such as only the tools for the patient side cart. 
     Joint locations and orientations are generally known from kinematic data provided, for example, by the kinematic component  92 . Utilizing this information, each component of the patient side cart may be rendered in location so as to generate a image of the patient side cart that appears in 3-D to the surgeon. Thus, in an embodiment, the modeling data  104  includes individualized information for each component or link of the patient side cart robot. 
     In accordance with an embodiment, the modeling component  108  constantly updates the location and/or orientation of the components of the synthetic image  120  in accordance with information provided by the tool tracking component  90  and/or the kinematic component  92 . For example, an initial state of the kinematic component  92  may be determined including a position of one or more end effectors for the patient side cart. These positions may be compared with position information provided by the tool tracking component  90 . As described above, the difference between the actual position as determined by the tool tracking component  90  and the estimated position of the end effectors provided by the kinematic component  92  may result in an offset, which may be stored in or otherwise used by the error correction component  94 . This offset may be used to register the position and orientation of an end effector as determined by the tool tracking component  90  to the position and orientation as estimated by the kinematic component  92 . 
     As data is available from the tool tracking component  90 , the actual position of the end effector may be tracked and registered with information provided by the kinematic component  92 . When tool tracking information is not available from the tool tracking component  90 , an assumption may be made that any change in kinematic information provided by the kinematic component  92  is an indication of actual movement by the end effector. That is, when tool tracking is not available, the position of an end effector may be accurately determined by the change in coordinate positions between the current position and the last known position, as calculated by the kinematic component  92 . The assumption here is that the change in position may be accurately calculated using only kinematic data, without tool tracking information. This assumption is reasonable, because although kinematic information is often not accurate for calculating a position of an end effector in space, it is typically accurate for calculating a change of position once a position is known, especially over a short period of time or for a small amount of movement. Thus, asynchronous data may be provided by the tool tracking component  90 , and synchronous data may be provided by the kinematic component  92 . The combination of this information provides data regarding the positions and orientations of the components of the patient side cart  40 . 
     The positions of the components of a robotic arm assembly may be determined by utilizing the joint states provided by the kinematic component. These joint states are calculated backwards from the end effector, the position of which is known, as described above. In addition, because the slave encoders  102  at the joints of robotic arm assemblies  122  for the patient side cart provide change in state information for each joint, the relative position of each section of the robotic arm assemblies may be accurately estimated and tracked. Thus, information can be provided to the modeling component  108  that is sufficient so that modeling component  108  may generate the synthetic image  120  by utilizing the modeling data  104 , with the position of each of the segments of the robotic arm assemblies  122 , including tools  124  at the end of the robotic arm assemblies, or an endoscope  126  at the end of one of the robotic arm assemblies. 
     Referring again to  FIG.  6   , in an embodiment, in addition to the synthetic image  120  for the patient side cart, a view volume  130  for the endoscope is provided. The view volume  130  represents a projection of the field of view of the endoscope  126 . The field of view is the view visible by the endoscope, and the view volume is a projection of the boundaries of the field of view. That is, the view volume  130  represents a 3-D space that is visible by the endoscope  126 . If desired, as shown in  FIG.  4   , camera information  132  may be provided to the modeling component  108 . The camera information includes a calibrated set of intrinsic and extrinsic parameters about the camera. The intrinsic parameters include, e.g., focal length and principle point, which model the perspective mapping of the optics. Additionally, the intrinsic parameters may account for lens distortion. The extrinsic parameters may account for, e.g., relative position and orientation between the stereo endoscopic views. As can be understood, changing the parameters, such as zoom, of the endoscope will change the view volume for the endoscope, such as making the view volume narrower or wider. In addition, as the endoscope  126  is moved, the view volume  130  will move accordingly. The camera information permits the creation of a 3-D stereo rendering that may be superimposed on the stereo view of the end effector from the image capture device, as described below. 
       FIG.  7    is a flowchart representing a process for updating a rendering of a synthetic image  120  in accordance with an embodiment. Beginning at  401 , the position and orientation of the patient side cart, or any portion thereof, is sensed. This sensing may occur, for example, via the tool tracking component  90  and/or the kinematic component  92 , as described above. 
     At  402 , the position and orientation information from  401  is used to generate a model (e.g., the synthetic image  120 ). As described above, the modeling component  108  uses the modeling data  104  to generate the model. The position and orientation information provided from  401  is utilized to correctly arrange the position and orientation of the synthetic model to match that of the patient side cart. 
     At  404 , as a result of the patient side cart moving, information is received. The movement may be, for example, movement of one of the robotic arm assemblies, movement of the endoscope, change in the focus of the endoscope, or movement by one of the end effectors. The movement of the end effector may be a change in location or orientation, including, for example, closing of pinchers or other operational movement of the end effectors. 
     At  406 , a determination is made whether tool tracking information is available. In the embodiment show in  FIG.  4   , the determination is whether an image is available so that the actual position of the end effector or any portion of the tool that is in a field of view (e.g., the view volume  130 ) of the endoscope  126  may be found using the tool tracking component  90 . In one aspect, if tool tracking is available, then  406  branches to  408  where the tool tracking information is utilized to update information about the position and orientation of the tool and/or end effector. 
     At  410 , the kinematic information is used to update information about the location and orientation of the joints of each linkage of the robot for the patient side cart. At  412 , the offset is updated, if desired. At  414 , the display of the synthetic image  120  is updated, and the process branches back to  404 . 
     At  406 , if the tool tracking information is not available, then the process branches to  416 , where the kinematic information provided by the kinematic component  92  is utilized to determine the position of the end effector. The process then proceeds to  410 , and then on through the process, although since the tool tracking information was not available on this loop, the offset will likely not be updated, skipping  412 . 
     Utilizing the method shown in  FIG.  7   , a 3-D rendering of the synthetic image  120  is generated, and the synthetic image accurately represents the physical configuration of the patient side cart at any point in time throughout a surgical procedure. This information can be utilized and viewed by the surgeon S, or by someone else, to evaluate the state of the patient side cart. As described below, the viewer  34  or the display  82  may show the synthetic image  120 , either from a point of view that is the same as the point of view from the endoscope, or from another angle or distance. The synthetic image  120  enables observation of all parts of the patient view cart via the viewer  32 , thus permitting the surgeon S to monitor movements of the robot and tools. In addition, in accordance with an embodiment, viewing of these components is available in connection with the view volume  130 , permitting a surgeon to have a good perspective of where the endoscope&#39;s field of view is with respect to space. The view volume  130  provides a three dimensional representation of what is being seen by the surgeon S when looking in the viewer  32 . 
     If desired, a single display may be provided for showing both the field of view of the endoscope and the synthetic image  120 . For example, as shown in  FIG.  8   , a view  200  provided by the viewer  32  or the display  84  provides both an actual field of view image  202  for the endoscope  126  and the synthetic image  120 . The synthetic image  120  is shown in a separate tile window  204 . In the embodiment shown in  FIG.  8   , the tile  204  is approximately the same size as the field of view  202 , but if desired, the tile window may be smaller or larger than the field of view  202 . Also, if desired, a toggle or other feature may be provided so that the surgeon may switch back and forth between a larger presentation of the synthetic image  120  or the field of view  202 . In addition, the synthetic image  120  and/or the tile window  204  may be partially superimposed over a portion of the field of view, either on a continuous basis or upon request. 
     As an example of toggling back and forth between a larger presentation of the synthetic image  120  or the field of view  202 , a camera control may be provided that is connected to the master manipulators. For example, a user may start looking at the endoscopic view and may pull the endoscope back by pulling the his hands towards himself while in a camera control mode. At some point, the endoscope cannot be pulled back any farther, and the field of view encompasses a maximum area. Continuing to pull back on the master controls (with or without a haptic detent or other indication) can expose a view showing sections of a synthetic image  120  along the borders of the real image (e.g., the image captured in field of view  202 ). Pulling back even farther on the master controls (with or without haptic detent or other indication) may provide a view where the image captured in field of view  202  is only the middle section of the screen. Pulling back still farther on the controls (with or without haptic detent or other indication) may provide the entire synthetic image  120 . Reversing the master control direction can be used to reverse such a real-to-synthetic zoom out function and control a synthetic-to-real zoom in function. As an alternative to camera control using master manipulator movement, the system may be configured to use another control input (e.g., a foot pedal, a finger button on a manipulator, the roll of the master manipulator grip, and the like) to control the zoom functions. 
       FIG.  9    shows a tile window  208  displaying an alternate angle for viewing a portion of the synthetic image  120 . In the embodiment shown, the view volume  130  is slightly tilted from the actual field of view of the endoscope, but the particular angle of view of the view volume  130  shows relevant information regarding the configuration of the tools  124  with respect to the view volume. 
     The features of the synthetic image  120  provide another number of benefits to a user of the minimally invasive telesurgical system  20 . Some of these advantages are set forth below. 
     Collision Detection 
     Typically, in a minimally invasive telesurgical system, only the most distal portions of the surgical tools, such as the tools  124 , may be visible to the surgeon in the field of view of the endoscope  126  at any time. Depending upon the configuration of the patient side cart, it is possible that collisions between moving parts of the robot assembly may occur which are not visible to the surgeon in the field of view. Some of these collisions (“outer collisions” because they are outside of the field of view for the endoscope  126 ) may occur between the linkages of robotic arm assemblies leading to the tools, the collisions may occur between two tools, or may occur between a tool and a linkage. Such outer collisions may occur outside the body or inside the body but not within the field of view. In addition, an outer collision may occur between one tool that is in the field of view and another tool that is slightly outside the field of view. Collisions occurring inside the body and in the field of view of the endoscope are “inner collisions”. 
     In accordance with an embodiment, the synthetic image  120  and/or the information generated by the modeling component  128  may be utilized for collision detection. As an example, a surgeon viewing the viewer  32 , or another individual viewing the display  84 , may view the synthetic image  120  to see an indication of an imminent or actual collision. 
     Collision detection may involve more than just a visual image of a collision. Information about relative locations of robot linkages and tools is maintained by the modeling component  128 , and this information may be used to generate a signal if two components are sensed to be too close to one another. For example, each tool may be treated like a capsule or cylinder, having a particular radius or buffer zone outside the tool&#39;s surface. Using the actual position information from the tool tracking component and/or the kinematic information from the kinematic component  92 , the modeling component  108  may predict or warn of a collision. For example, if two tools  124  are presumed to have a radius of one half inch each, then if the center line for one of the tools comes within an inch of the center line for a second tool, then the modeling component  108  may assume that a collision has occurred. A separate signal may be generated if the two tools are calculated to be close, but not in contact, with each other. For the above example, this distance may be, e.g., a center line distance between the tools of 1.20 inches. 
       FIG.  10    shows at the bottom a display tile window in which a real field of view image  250  shows two tools  252 ,  254  colliding. Although the collision in  FIG.  10    is within the field of view  250 , as described above, the collision may take place outside the field of view or even outside the body of the patient. Even if inside the field of view, the tools  252 ,  254  are not necessarily visible, because they may be blocked by cauterization smoke, blood, or an organ, as examples. In  FIG.  10   , the inner collision is seen in the field of view  250 , but it is also detected by the modeling component  108 . 
     At the top of  FIG.  10    is a display tile window  260  representing the synthetic image  120 . In the embodiment shown in  FIG.  10   , the tile window  260  is taken from the same point of view as the field of view  250 , but a different point of view may be provided as described above. In addition, as described above, outer collisions, as well as inner collisions, may be detected. 
       FIG.  11    is a flowchart showing an illustrative process for providing collision information in accordance with an embodiment. The process begins at  1100 . At  1102 , a model, such as the synthetic image  120 , is generated. This generation process is described with reference to  FIG.  7   . At  1104 , the robot for the patient side cart is moved. At  1105 , the proximity of linkages and/or tools of the robotic arm assemblies  122  are computed. At  1106 , a determination is made whether the proximities are within a high threshold. The high threshold represents spacing between tools or linkages at which a warning of a collision is given. For example, as described above, if two tools are assumed to have a radius of a half an inch, the high threshold may be a centerline separation of 1.2 inches. If the components of the patient side cart are not within the high threshold,  1106  branches back to  1104 , and the robot continues to move. 
     If two components of the patient side cart are within the high threshold, then  1106  branches to  1108 , where a warning is generated. This warning may be an audible warning, a visual warning (e.g., provided within the viewer  32  or on the display  84 ), or another suitable indication of collision proximity. If visual, the warning may be presented, for example, in the field of view  250  ( FIG.  10   ). In the embodiment shown in  FIG.  10   , the words “inner collision error” are shown, indicating an actual collision. Alternatively, for a warning message, a message stating that tools are too close or similar may be provided. In addition, for the view of the synthetic image  120 , the color of the tools  124  may change to provide the warning, such as changing from a metal color to yellow for a warning. 
     A surgeon may or may not elect to rearrange the robot after the warning is generated at  1108 . In either event, the process proceeds to  1110 , where the robot has moved again. At  1112 , a determination is made whether the robot is within a low threshold. In an embodiment, the low threshold represents a distance, such as a center line distance, at which a collision is assumed. If the low threshold is not met, the process branches back to  1104  and continues to loop, likely continuing to generate the warning message unless the components of the patient side cart are moved to outside the high threshold in  1106 . 
     If the components are within the low threshold, then  1112  branches to  1114 , where collision information is generated, such as a collision warning or message. As an example, in  FIG.  10   , the collision error warning is provided in the field of view  250 . (Both near and actual collision warnings may use the same or different indications.) A similar collision error warning may be provided in the tile window  260 , and the tools  124  may change colors, such as to red, to show a collision error. The process then loops back to  1104 . 
     As stated above, for collision detection, the components need not be in the field of view of the viewer  32 . Thus, when components of the patient side cart are improperly aligned and are approaching a collision or actually have a collision, information may be provided, either in visual form or in the form of a warning or error message. The warning may be particularly helpful where a user is not familiar with operation of the robot and may put the tools or robotic arm assemblies in an awkward position. The person viewing the viewer  32  may select a different synthetic view angle and distance of the robot so as to determine the near collision or actual collision point between two robotic manipulators. Once the operator views the collision point, he or she may adjust one or more of the robot&#39;s kinematic arms (either the passive, “set up” portions or the actively controlled, manipulator portions) to cure the actual or near collision condition and avoid further collisions. In one aspect, if the operator is viewing a synthetic view that corresponds to the endoscope&#39;s field of view, the synthetic view may be automatically changed to show a collision point if a collision warning or actual collision is occurring. 
     In an embodiment, the location of a patient and/or portions of the patient&#39;s tissue structures (e.g., from preoperative imaging or by other suitable method of registering tissue structure locations) may be provided to the system, and registered patient location data may be to detect, warn, and display actual or potential collisions between the robot and the patient or designated tissue structures in the patient. Collisions may be detected as described above. 
     Also, in an embodiment, a visual, audio, or other indicator may be provided to assist in reducing or correcting a collision state. For example, for the warning situation described above, information may be provided to a surgeon to aid the surgeon in avoiding a collision. For example, a visual indicator may provide information about a movement direction in which a collision might occur, or may indicate a movement direction for the surgeon to make in order to avoid or cure a collision. 
     Lost Tool Recovery 
     In minimally invasive surgery, it is possible for instruments to be positioned outside the endoscopic camera&#39;s view volume. This possibility can result in situations where the tool is effectively lost, since the surgeon does not necessarily know how to move the endoscope to bring the instrument back into view, or how to move the instrument into the endoscope&#39;s field of view. Moreover, the situation may compromise patient safety, since the surgeon is able to move an instrument which cannot be observed. 
     The synthetic image  120  provides a solution to this problem by presenting the surgeon with a broader view of the endoscope&#39;s view volume  130 , along with an accurate depiction of the position of each tool  124 . Such a broader view and tool depiction may be provided from various points of view. In an embodiment, the broad view and tool depictions are provided from the same point of view or direction as the endoscope field of view. By providing a broad view in this direction, the surgeon will be able to retain the intuitive tool control movement he or she normally experiences when viewing the real endoscopic image while moving tools into the proper position so that the tool is back in the view volume  130 . Alternatively, the view volume  130  may be viewed from other angles, allowing a surgeon to have a different perspective of what the endoscope  126  is viewing. As examples,  FIGS.  8  and  9    show three different views, taken at different angles and pans, of views that may be shown for the synthetic image  120 . Although the lower part of  FIG.  8    shows an actual image, a synthetic image  120  may be provided from the same direction, and would look similar except that synthetic tools would be shown instead of video feed of the actual tools. The view established by the field of view is shown in the lower part of  FIG.  8   , and a view taken from a front side of the synthetic image—zoomed outward to show much of the patient side cart—is shown in the top of  FIG.  8   . A view taken slightly rearward and upward of the direction of the field of view of the endoscope, and zoomed outward to show the view volume  130 , is shown in  FIG.  9   . This slight variation in view provides a good perspective of where the tools  124  are with respect to the view volume  130 . A surgeon may toggle between a view consistent with the field of view and one just off from the field of view, such as shown in  FIG.  9   . To this end, a controller or other device may be provided for allowing a surgeon to toggle between different views of the synthetic image  120 . Alternatively, a separate controller or the master controller may be utilized to allow infinite positioning (e.g., various pan, tilt, roll, dolly, truck, crane, and zoom image movements) of the synthetic image  120 . 
       FIG.  12    is a flow chart representing a process for lost tool recovery in accordance with an embodiment. The process begins at  1200 . At  1202 , the synthetic image  120  is generated as described above. At  1204 , the patient side cart, or the robot, is moved. 
     At  1206 , a determination is made whether one or more of the tools is outside of the field of view. If not, the process loops back to  1204 . If one or more of the tools is outside of the field of view, then the process may move to  1208 , where a synthetic image is shown. The synthetic image may or may not be automatically shown; the synthetic image display may be selected by a surgeon. To this end,  1208  may be done as a result of a request by the surgeon or another operator, and may or may not be triggered by a tool being out of the field of view. If desired, however, a synthetic image may be automatically shown as a result of a loss of an image of the tool. In such an embodiment, however, it may be desirable to show the synthetic image in a tile window in addition to the field of view, instead of taking the field of view away from the surgeon. 
     If the missing tool display option is available, the synthetic view  120  may be requested or otherwise provided in  1208 . The synthetic image provided in  1208  may be, as described above, substantially the same as the field of view of the endoscope  126  or any number of perspectives of the modeled system. If a desired angle is not shown, then a surgeon may elect at  1210  to show a different view. If the surgeon elects to show a different view, then  1210  branches to  1212 , where the synthetic image  120  is, e.g., rotated to show a different view. If desired, as part of this movement, the synthetic image may rotate in space so that the surgeon may get an idea of the position from which the view started relative to the position where the view is going. In addition, in accordance with an embodiment, when a view of the synthetic image  120  is inconsistent with the same point of view as the field of view, a warning message or other indicator may be provided to the surgeon so that the surgeon may understand that he or she is looking at the view volume  130  from a direction that is different than the direction of the field of view. 
     If the surgeon did not request a different view in  1210 , then the process loops back to  1204 . 
     As described above, the synthetic image  120  provides an image of the patient side cart that is larger than and outside of the view volume  130 . Thus, even if taken along the same point of view as the field of the view of the endoscope  126 , the surgeon may zoom outward so that tools that are just outside the view volume  130  may be seen. The surgeon may then move these tools or the endoscope to the desired position so that they are within the field of view. 
     Mixed Video and Rendered View 
     As described above, there are a number of ways in which the system may present the synthetic image  120  of the robot to the surgeon. A first option, described with respect to  FIG.  8   , includes a tile window  204  showing a synthetic view above the field of view image  202 , with both shown at the same time. Another option, shown in  FIG.  9   , shows only the synthetic image  120 . 
     In accordance with an embodiment, a third option is provided in which a video display from an endoscope is superimposed over the synthetic image  120 , with the positions matched, so that the video image is rendered in the context of the synthetic image  120  of the entire patient side cart. This view provides relative positions of the components of the patient cart for the surgeon, and allows the surgeon to understand where the surgeon is with respect to space. The view is also well suited when transitioning between a pure video display and a pure synthetic image  120 . During the transition, the surgeon can relate respective positions of the robot and the video image from the endoscope. 
     A simplified version of this feature is shown in  FIG.  13   , where an image within the field of view  300  is projected over a window tile  306  that includes the synthetic image  120 . The field of view image  300  includes two tools  302 ,  304  performing an operation. The window tile  306  extends the view provided by the field of view  300 , and additional sections of the tools  302 , 304 —indicated by the reference numerals  308 , 310 , respectively—are provided. The surgeon may zoom in and out to provide additional information about the location of the tools with respect to other parts of the patient side cart. In addition, the features described with respect to the embodiment shown in  FIG.  13    may be utilized to find the lost tool that is just outside the field of view, for example, in the window tile  306 , but not in the field of view  300 . 
     Visual Troubleshooting Indicator 
     In accordance with an embodiment, instead of or in addition to the synthetic image  120 , the modeling data  104  may be utilized to project a image other than a visual representation of portions of the patient side cart. For example, using the position information provided by the tool tracking component  90  and/or the kinematic component  92 , the modeling component  108  may display a portion of the synthetic image  120  in a different color, or it may display text on a portion of the synthetic image or instead of the synthetic image. In such an embodiment, the text may be superimposed over the actual tools in a field of view so as to focus attention on that tool or to provide other information. As an example, for the tool  304  in  FIG.  13   , the modeling component  108  may be utilized to display a text message “closed”  320  collocated over the video image of the tool  304  to indicate that the clamp for the tool is closed. The camera information, described above, permits the creation of a 3-D stereo rendering that may be superimposed on the stereo view of the tool  304  from the image capture device. Error messages may also be provided. 
       FIG.  14    is a flow chart representing a process for displaying information utilizing the modeling component  108  in accordance with an embodiment. Beginning at  1400 , the location of the components of the patient side cart is determined, for example, the location of the tools  124 . At  1402 , the modeling component  108  is aligned with the tool as described above. At  1404 , the desired information is displayed over the tool. For example, as described above, words may be displayed over the tool. In addition, if desired, information may be displayed around or adjacent to a tool or other feature. 
     As can be understood, to superimpose a message over actual tools in the field of view, the modeling data  104  need only include information about the outer perimeter of the tools. The other components of the patient side cart are not needed for this embodiment. 
     Communication Aid 
     The synthetic image  120  may be useful in providing a remote image of the operation of the patient side cart. For example, in some situations, an individual remote from the patient side cart may desire to view operation of the patient side cart. In such a situation, the synthetic image  120  may be rendered at both the viewer  32  and a remote display (e.g., the display  84 ). In such a situation, in accordance with one embodiment, the modeling data may be maintained all at one location, with the synthetic image  120  sent to a remote location for display at the remote location. 
     In an alternate embodiment, position and orientation information provided by the tool tracking component  90  and/or the kinematic component  92  may be sent to a remote computer. The remote computer, in turn, includes a modeling component  108  and the modeling data  104 . In this embodiment, the synthetic image  120  is generated at the remote location in a separate operation from producing the synthetic image  120  for the viewer  32 . 
     Being able to provide a synthetic image  120  in remote locations permits an operating surgeon viewing the surgeon&#39;s console to communicate with a surgical assistant viewing an assistant monitor. In addition, a student surgeon at one surgeon console may communicate with a remote proctor at another surgeon console. 
     In accordance with another embodiment, a remote user or proctor may have controls for movement of a synthetic image, such as a synthetic image  120 . The movement of the synthetic image may be watched by a surgeon or student at the surgeon console, permitting the user to learn surgical procedures and motions, and to mimic those motions with the surgeon or student&#39;s controls (and thus the tools). 
     Range of Motion Limits 
     The linkages for the robotic arm assemblies of the patient side cart have a limited range of movement, limiting the movement of the tools supported by each arm or linkage. When the robot for a patient encounters range of motion limits, it is not always obvious to a surgeon (new or experienced) why the robot is not able to continue moving. In a telesurgical system, there are typically two sources of range of motion limits: joint limits of the master manipulator and joint limits of the slave manipulator. 
     In accordance with an embodiment, the modeling component  108  generates a signal to indicate that a limit of the range of movement for a tool is approaching. The signal may be used, for example, to generate a visual cue to the surgeon, such as color coding of the part(s) that have reached a limit. Alternatively, the limit may be represented with synthetic geometry as a virtual wall  340  ( FIG.  6   ), which may be shown with the synthetic model  120 , or may alternately be superimposed over the field of view. The virtual wall  340  is for the right-most tool  124 , and it may be shown as concave, flat, or otherwise shaped to match the curvature of a range of motion. The virtual wall  340  is displayed in a position and direction that is perpendicular to the impeded motion direction of the instrument tip. 
     Other variations are within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, a certain illustrated embodiment thereof is shown in the drawings and has been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.