Patent Publication Number: US-2023157776-A1

Title: Systems and methods for constraining a virtual reality surgical system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application 62/487,833 filed Apr. 20, 2017, which is incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The present disclosure is directed to systems and methods for performing a medical procedure or training for a medical procedure using a virtual reality display system and more particularly to systems and methods for providing constraints within a surgical system or surgical training system when using a virtual reality display system. 
     BACKGROUND 
     Minimally invasive medical techniques are intended to reduce the amount of tissue that is damaged during invasive medical procedures, thereby reducing patient recovery time, discomfort, and harmful side effects. Such minimally invasive techniques may be performed through natural orifices in a patient anatomy or through one or more surgical incisions. Through these natural orifices or incisions, clinicians may insert medical tools to reach a target tissue location. Minimally invasive medical tools include instruments such as therapeutic instruments, diagnostic instruments, and surgical instruments. Minimally invasive medical tools may also include imaging instruments such as endoscopic instruments that provide a user with a field of view within the patient anatomy. Some minimally invasive medical tools and imaging instruments may be teleoperated or otherwise computer-assisted. When performing teleoperational procedures or providing training simulations for teleoperational procedures, head-mounted display systems may be used to provide the clinician with an immersive augmented-reality or virtual reality experience. System controls are needed to provide for safe and reliable operation of teleoperational systems when using an immersive display system. 
     SUMMARY 
     The embodiments of the invention are summarized by the claims that follow below. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory in nature and are intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure. In that regard, additional aspects, features, and advantages of the present disclosure will be apparent to one skilled in the art from the following detailed description. 
     In one embodiment a method of operating a surgical control system comprises displaying an image of a surgical environment, from a field of view of an imaging instrument, on a display system. The display system is configured for mounting to a head of a user. The method also includes detecting an imaging control input from the user and responsive to the detection of the imaging control input, enabling an imaging control mode of the surgical control system. The method also includes detecting a movement of the head of the user. While the surgical control system is in the imaging control mode and responsive to the user&#39;s head movement, an image of the surgical environment from a changed field of view of the imaging instrument is displayed. The changed field of view corresponds to the detected movement of the user&#39;s head. 
     In another embodiment, a method of operating a surgical control system comprises generating an image of a surgical environment from a viewpoint of an imaging tool having a field of view. A surgical instrument is positioned within the surgical environment. The method also includes displaying the image of a surgical environment on a display system. The display system is configured for mounting to a head of a user. The method also includes detecting a movement of the head of the user and determining if the movement of the user&#39;s head is within a boundary corresponding to the imaging tool field of view. If the movement of the user&#39;s head is within the boundary, the image of the surgical environment on the display system is changed by generating a changed viewpoint in the imaging tool field of view that corresponds with the detected movement of the user&#39;s head. 
     In another embodiment, a method of operating a surgical control system, the method comprises generating an image of a surgical environment. A surgical instrument is positioned within the surgical environment and is coupled to a manipulator arm having a range of motion. The method also includes displaying the image of a surgical environment on a display system. The display system is configured for mounting to a head of a user. The method also includes detecting a manipulator arm input motion from the user and determining if the manipulator arm input motion corresponds to movement of the manipulator arm within the range of motion. If the movement of the manipulator arm input motion corresponds to movement outside the range of motion of the manipulator arm, a ghost image of the surgical instrument is generated, wherein the ghost image moves in correspondence with the manipulator arm input motion. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
         FIG.  1   a    provides a view of a surgical environment including a teleoperational surgical system including an immersive display system. 
         FIG.  1 B  provides a view of a simulated surgical environment including a teleoperational surgical system including an immersive display system. 
         FIG.  2    provides a field of view image from an imaging instrument. 
         FIG.  3    illustrates a hand controller of a teleoperational surgical system. 
         FIG.  4    is a flowchart providing a method for entering and exiting a virtual explore mode of the teleoperational surgical system. 
         FIGS.  5 - 8    illustrate a surgical environment, an external environment, and displayed images on an immersive display system. 
         FIG.  9    is a flowchart providing a method for operating within an imaging control mode of the teleoperational surgical system. 
         FIG.  10    illustrates a surgical environment, an external environment, and displayed images on an immersive display system. 
         FIG.  11    illustrates a method for entering and operating within a virtual manipulator arm mode of a teleoperational system. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is intended. In the following detailed description of the aspects of the invention, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be obvious to one skilled in the art that the embodiments of this disclosure may be practiced without these specific details. In other instances well known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the embodiments of the invention. 
     Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. In addition, dimensions provided herein are for specific examples and it is contemplated that different sizes, dimensions, and/or ratios may be utilized to implement the concepts of the present disclosure. To avoid needless descriptive repetition, one or more components or actions described in accordance with one illustrative embodiment can be used or omitted as applicable from other illustrative embodiments. For the sake of brevity, the numerous iterations of these combinations will not be described separately. For simplicity, in some instances the same reference numbers are used throughout the drawings to refer to the same or like parts. 
     The embodiments below will describe various instruments and portions of instruments in terms of their state in three-dimensional space. As used herein, the term “position” refers to the location of an object or a portion of an object in a three-dimensional space (e.g., three degrees of translational freedom along Cartesian X, Y, Z coordinates). As used herein, the term “orientation” refers to the rotational placement of an object or a portion of an object (three degrees of rotational freedom—e.g., roll, pitch, and yaw). As used herein, the term “pose” refers to the position of an object or a portion of an object in at least one degree of translational freedom and to the orientation of that object or portion of the object in at least one degree of rotational freedom (up to six total degrees of freedom). 
     Referring to  FIG.  1   a    of the drawings, a surgical environment  10  includes a teleoperational medical system  11  for use in, for example, medical procedures including diagnostic, therapeutic, or surgical procedures. The teleoperational medical system generally includes a teleoperational assembly mounted to or near an operating table O on which a patient P is positioned. The teleoperational assembly may include one or more modular manipulator arms  12 . A medical instrument system  14  or an imaging system  15  may be operably coupled to a teleoperational manipulator (e.g. an arm) of the teleoperational assembly. The imaging system may be, for example, a stereoscopic endoscope imaging system. An operator input system  16  allows a surgeon S or other type of clinician to control the operation of the medical instrument system  14  and/or the imaging system  15 . One or more assistant surgeons, anesthesiologists, or support personnel may also be present in the surgical environment. 
     The teleoperational medical system also includes a display system  17  which may present images captured by the imaging system  15 , surgical navigation and guidance images, and/or alphanumeric or symbolic information to assist the surgeon or assistants with the surgical procedure. The display system may be, for example, an immersive display system worn by the surgeon S. More specifically, the immersive display system may be a head-mounted display system for presenting an image of the interior anatomical environment from the imaging system  15 , augmented or virtual images of the interior anatomical environment, images from external of the patient anatomy, interactive user interfaces, or other image-based, graphical, or textual information to the surgeon S. The head-mounted display system may be worn as a set of glasses or goggles covering both of a user&#39;s eyes.  FIG.  2    illustrates a field of view image  30  from an imaging instrument  15  positioned within the interior anatomy of the patient P. The image  30  may be displayed on the display system  17 . With stereoscopic image data, multiple viewpoints may be generated from the field of view stereoscopic image data while the imaging instrument is held in a static position. Thus, with an immersive display system, the field of view may be presented with slightly different viewpoint images as the user&#39;s head moves the display system. This may provide the user with a more immersive experience when viewing the field of view. 
     The teleoperational medical system also includes a control system  20  in communication with the operator input system  16 , the teleoperational assembly and the display system  17 , as described below. 
     In this embodiment, the operator input system  16  includes one or a set of operator hand controllers  18  ( FIG.  3   ) for controlling one or multiple medical instrument systems  14  or the endoscopic imaging system  15 . The input system also may include other types of user inputs including pedal inputs, gaze tracking, voice command recognition, head gesture recognition. In various alternatives the operator hand controllers  18  may be tethered by power and/or signal transmission cabling or may be untethered/wireless. As shown in  FIG.  3   , the operator controller  18  may include one or more of any number of a variety of input devices such as grip inputs  22  and trigger switch  24 . The input devices may be used to, for example, move a distal end of an endoscopic imaging system within the patient P, close grasping jaw end effectors, apply an electrical potential to an electrode, deliver a medicinal treatment, or the like. In various alternatives, the operator input system may additionally or alternatively include joysticks, trackballs, data gloves, trigger-guns, hand or foot-operated controllers, voice recognition and control devices, touch screens, body motion or presence sensors, and the like. In some embodiments, the hand controller  18  will be provided with the same degrees of freedom as the medical instruments of the teleoperational assembly to provide the surgeon with telepresence, the perception that the control device(s) are integral with the instruments so that the surgeon has a strong sense of directly controlling instruments as if present at the surgical site. In other embodiments, the hand controller  18  may have more or fewer degrees of freedom than the associated medical instruments and still provide the surgeon with telepresence. 
     The manipulator arms  12  support and manipulate the medical instrument system  14  and/or the imaging system  15  while the surgeon S conducts the procedure from the patient side or another location within the surgical environment. The number of medical instrument systems  14  used at one time will generally depend on the diagnostic or surgical procedure and the space constraints within the operating room among other factors. Each arm  12  of the teleoperational assembly may include a kinematic structure of one or more servo or non-servo controlled links. The teleoperational arm  12  may also include a plurality of motors that drive inputs on the medical instrument system  14  or imaging system  15 . These motors move in response to commands from the control system  20 . The motors include drive systems which when coupled to the medical instrument system  14  or imaging system  15  may move the systems into or out of a naturally or surgically created anatomical orifice. Other motorized drive systems may move the distal end of the systems in multiple degrees of freedom, which may include three degrees of linear motion (e.g., linear motion along the X, Y, Z Cartesian axes) and in three degrees of rotational motion (e.g., rotation about the X, Y, Z Cartesian axes). Additionally, the motors can be used to actuate an articulable end effector of the instrument for grasping tissue in the jaws of a biopsy device or the like. Instruments  14  may include end effectors having a single working member such as a scalpel, a blunt blade, an optical fiber, or an electrode. Other end effectors may include, for example, forceps, graspers, scissors, or clip appliers. 
     The control system  20  includes at least one memory and at least one processor, and typically a plurality of processors, for effecting control between the medical instrument system, the imaging system  15 , the operator input system  16 , the display system  17 , and other auxiliary systems which may include, for example, additional imaging systems, audio systems, fluid delivery systems, display systems, illumination systems, steering control systems, irrigation systems, and/or suction systems. The control system  28  also includes programmed instructions (e.g., a computer-readable medium storing the instructions) to implement some or all of the methods described in accordance with aspects disclosed herein. While control system  20  is shown as a single block in the simplified schematic of  FIG.  1   a   , the system may include two or more data processing circuits with one portion of the processing optionally being performed on or adjacent the teleoperational assembly, another portion of the processing being performed at the operator input system  16 , and the like. The control system  20  may employ any of a wide variety of centralized or distributed data processing architectures. Similarly, the programmed instructions may be implemented as a number of separate programs or subroutines, or they may be integrated into a number of other aspects of the teleoperational systems described herein. In one embodiment, control system  20  supports wireless communication protocols such as Bluetooth, IrDA, HomeRF, IEEE 802.11, DECT, and Wireless Telemetry. 
     In some embodiments, control system  20  may include one or more servo controllers that receive force and/or torque feedback from the medical instrument system or the imaging system. Responsive to the feedback, the servo controllers transmit signals to the operator input system  16 . The servo controller(s) may also transmit signals instructing teleoperational assembly to move the medical instrument system(s)  14  and/or endoscopic imaging system  15  which extend into an internal surgical site within the patient body via openings in the body. Any suitable conventional or specialized servo controller may be used. A servo controller may be separate from, or integrated with, teleoperational assembly. In some embodiments, the servo controller and teleoperational assembly are provided as part of a teleoperational arm positioned adjacent to the patient&#39;s body. 
     The control system  20  can be communicatively coupled with the imaging system  15  and can include a processor to process captured images for subsequent display, such as to a surgeon on the surgeon&#39;s console, or on another suitable display located locally and/or remotely. For example, where a stereoscopic endoscope is used, the control system  20  can process the captured images to present the surgeon with coordinated stereo images of the surgical site. Such coordination can include alignment between the opposing images and can include adjusting the stereo working distance of the stereoscopic endoscope. 
     As shown in  FIG.  1 B , the control system  20 , operator input system  16  and immersive display system  17  may also be used to conduct a procedure with a simulated surgical environment  40 . The simulated surgical environment  40  may be viewed on the immersive display system  17  by the user S. In one embodiment, the simulated surgical environment is a three dimensional, virtual-reality environment representing a surgical environment that may be used for designing and providing clinician training. The field of view of a simulated imaging system may appear similar to a live field of view image  30 . The simulated surgical environment may be a pre-recorded image of a patient anatomical environment, a computer-generated illustration of a patient anatomical environment, or a hybrid of the two. In the simulator environment, virtual instruments in the field of view image may be operated using the hand controllers  18 . Likewise, the hand controllers may be used to adjust the simulated field of view by moving a simulation imaging system (e.g. a virtual endoscope). In various embodiments, the simulated surgical environment may be a complete virtual reality environment in which movements of the user S, such as head movements or inputs to the input system  16 , are tied to parameters of virtual components (e.g., virtual instruments, a virtual imaging system) in the virtual reality environment. In these entirely virtual simulated environments, user movements are not tied to physical components in a physical surgical environment. In some embodiments, user inputs may be provided by tracked gaze or head motion, without the use of hand controllers. 
     In alternative embodiments, the simulated surgical environment may be a physical, artificial surgical environment designed to mimic a natural anatomy or to provide specialized procedure training. In these alternative embodiments, user inputs may be tied to physical components active in the artificial environment. In still other alternative embodiments, the simulated surgical environment may be a hybrid environment including both virtual reality elements and physical components. 
     The immersive display systems allow a user to experience a live or simulated surgical environment as if the user were present within the environment. A head mounted immersive display system physically allows a user to have full range of translational and rotational motion that may not correspond to the physical constraints imposed by the kinematics and safety features of the teleoperational system. The systems and methods described below may be implemented to impose constraints on or augment the user&#39;s experience when using an immersive display system in a live or simulated surgical environment. 
     In a traditional teleoperational surgical system in which a user is positioned at a stationary operator console, the system enters an engagement mode (also known as a “head-in” mode) when sensors detect that the user&#39;s head is positioned in a viewfinder and the user is able to visualize the surgical environment displayed in the viewfinder via images captured by the imaging system. The “following mode” of a teleoperational medical system is a system operational state in which the movement of the operator input system, such as the hand controllers, effects movement of the instruments positioned in the patient anatomy. Generally, before the teleoperational medical system can enter the following mode for performing a surgical procedure, the system must first be in the engagement mode. To safely perform a teleoperational procedure with a traditional system, movement of the instruments within the patient anatomy may be suspended when the operator looks away or otherwise exits the engagement mode, indicating that the display system is not visible to the operator. 
     When the display system is not in a fixed position within an operator console, as is the case with an operator-mounted immersive display system, the teleoperational system may be constrained or augmented to provide a virtual engagement mode that indicates the operator is able to visualize the surgical environment in the immersive display prior to entering an instrument following mode.  FIG.  4    is a flowchart providing a method  100  for entering and exiting virtual engagement and virtual explore modes of a teleoperational surgical system. The teleoperational surgical system may be, for example a teleoperational surgical system  11  for use in a live surgical environment  10  or a simulator environment  40 . The method  100  is illustrated in  FIG.  4    as a set of operations or processes  102  through  114 . Not all of the illustrated processes  102  through  114  may be performed in all embodiments of method  100 . Additionally, one or more processes that are not expressly illustrated in  FIG.  4    may be included before, after, in between, or as part of the processes  102  through  114 . In some embodiments, one or more of the processes may be implemented, at least in part, in the form of executable code stored on non-transitory, tangible, machine-readable media that when run by one or more processors (e.g., the processors of control system) may cause the one or more processors to perform one or more of the processes. 
     At a process  102 , an image of a surgical environment visible in the field of view of an imaging instrument is displayed. The image is displayed on a user-mounted immersive display system. With reference to  FIG.  5   , a surgical environment  202  (e.g., an interior anatomy of a live patient or a simulated surgical environment) may be visible with an imaging instrument  204  having a current field of view  206  and a potential field of view  208 . The potential field of view may be defined by the range of motion of the imaging instrument  204 . An environment  214  is external to the surgical environment  202 . A user  201  (e.g., a surgeon S) wearing a head-mounted immersive display system  203  (e.g., display system  17 ) has a view direction  210  toward the current field of view  206 . A visible image  212  is presented on the display system  203 . In this position the user may be in a virtual engaged mode. In the virtual engaged mode, the user visualizes the current field of view. From the virtual engaged mode, the instrument following mode may be entered in which instruments in the field of view may be moved under control of the operator input system. 
     At a process  104 , movement of the user&#39;s head is detected. At a process  106 , a determination is made as to whether the user&#39;s head (or a portion of the head such as the eyes) is within a boundary that corresponds to and allows the user to view the field of view. The position and view direction of the user&#39;s head may be evaluated to determine whether the current field of view is visible to the user. 
     At a process  108 , if the head movement has not exceeded the boundary and/or the user&#39;s head remains directed toward the current field of view, the image on the display system is still an image of the field of view  206 . If the image data is three dimensional, for example from a stereoscopic endoscope instrument, the image of the field of view may be presented from a slightly different viewpoint corresponding to the detected movement of the user&#39;s head. As shown in  FIG.  6   , the head of the user  201  has moved, but the user&#39;s eye view direction  210  is directed toward the current field of view  206  and the user&#39;s head and eyes are within a boundary  205  corresponding to the field of view  206 . Thus the visible image  212  is an image of the field of view  206  from a slightly shifted viewpoint corresponding to the movement of the user&#39;s head. 
     At a process  110 , if the head movement has exceeded the boundary and/or the user&#39;s head is not directed toward the current field of view, the image on the display system changes to notify the user that the field of view is not visible on the display system. For example, at an optional process  110 , the teleoperational system may enter a virtual explore mode. In another example at an optional process  112 , the teleoperational system may provide an alert. In the example embodiments of  FIGS.  7  and  8   , movement of the user&#39;s head is such that the user&#39;s eyes are now outside of the boundary  205  and the view direction  210  is no longer directed toward the current field of view  206 . Optionally, a message  212   b  may be displayed on the display system  203  to alert the user that he has moved outside the current field of view. The message may include text, graphics, or other images to alert the user or direct the user&#39;s head back toward the field of view. The teleoperational system may suspend following mode such that movement of the hand controllers do not move the surgical instruments in the surgical environment. 
     Optionally, the teleoperational system may enter a virtual explore mode in which image  212   a  on the display system is a virtual user interface that may include images of an environment  214  outside the surgical environment such as an external environment surrounding the patient or another remote viewpoint, separated from the viewpoint of the imaging instrument. Alternatively the virtual user interface may allow the use to access, for example, an interactive control menu for controlling features of the teleoperational system, status information about the patient or components of the teleoperational system, or a see-through image of the environment in front of his head. 
     At a process  114 , directions may be provided to lead the user to move his eyes back within the boundary so that the field of view  206  is again visible. Directions may be, for example, in the form of an audio recording providing verbal instructions for head movement, a sound that changes as the movement of the head changes, a set of textual instructions, a graphical movement map, a visual homing beacon, or a scene of the field of view that changes color or focus as the direction of view moves toward the field of view. When the user&#39;s head matches the last field of view direction, teleoperational system may exit virtual explore mode and return to following or engagement mode. An audio, visual, or tactical indication may alert the user that virtual explore mode has been exited. 
     Alternatively the user may exit the virtual explore mode and re-enter an engagement mode, a following mode, or an imaging control mode at a newly calibrated head position. The user may provide an indication that the user is working from a new position or the system may receive an indication that a large translational movement (exceeding a threshold movement value and indicating that the user is working from a new position) has been detected. Based on the indication, the system may establish a new position, orientation, and set of head boundaries for the user&#39;s new location. From this new location, the position and view direction of the user&#39;s head may be evaluated to determine the user&#39;s current field of view. For example, if a user begins by standing on one side of a patient and then moves to the opposite side of the table, the system will initially enter the virtual explore mode as the user&#39;s head moves beyond the boundary. The system may exit the virtual explore mode and re-enter a mode, such as following or imaging control mode, on the opposite side of the table. With the new head position and orientation detected, the imaging system view displayed to the user is based on the user&#39;s new position and orientation. 
     The teleoperational system may be constrained to provide a virtual imaging control mode that requires the user input prior to moving the actual or simulated imaging instrument within the surgical environment.  FIG.  9    is a flowchart  300  providing a method for entering and operating within a virtual imaging control mode of a teleoperational surgical system. The teleoperational surgical system may be, for example a teleoperational surgical system  11  for use in a live surgical environment  10  or a simulator environment  40 . The method  300  is illustrated in  FIG.  9    as a set of operations or processes  302  through  312 . Not all of the illustrated processes  302  through  312  may be performed in all embodiments of method  300 . Additionally, one or more processes that are not expressly illustrated in  FIG.  9    may be included before, after, in between, or as part of the processes  302  through  312 . In some embodiments, one or more of the processes may be implemented, at least in part, in the form of executable code stored on non-transitory, tangible, machine-readable media that when run by one or more processors (e.g., the processors of control system) may cause the one or more processors to perform one or more of the processes. 
     At a process  302 , an image of a surgical environment visible in the field of view of an imaging instrument is displayed. The image is displayed on a user-mounted immersive display system. With reference to  FIG.  10   , a user  201  may want to change the current field of view  206  within the potential field of view  208  defined by the range of motion of the imaging system  204 . 
     At a process  304 , an imaging control input is detected. The imaging control input may be a clutching input that transitions the teleoperational system out of an engagement or following mode. For example, the image control input may be an input at a hand controller  18  such as pushing a button  24 . Other types of user inputs including switches, hand gestures, pedal movements or other type of deliberate user input may be a suitable image control input for initiating an image control mode. 
     At a process  306 , responsive to the detection of the imaging control input, the teleoperational system enters an imaging control mode. In the imaging control mode, the field of view of the imaging instrument may be changed by moving the imaging instrument within the instrument&#39;s range of motion. In the imaging control mode, the surgical instruments are locked in place and movement of the operator input system does not cause a corresponding motion of the surgical instruments. In the imaging control mode, the imaging instrument may be moved in response to a user motion such as movement of the user&#39;s head or movement of operator input system. 
     At a process  308 , movement of the user&#39;s head is detected. Alternatively another type of user input such as movement of a hand controller  18  may be detected. For example, with reference to  FIG.  10   , a movement  211  of the head  201  may be detected. The view direction  210  changes with the movement of the user&#39;s head. 
     At a process  310 , the field of view of the imaging instrument changes from field of view  206  to field of view  207 . Field of view  207  is the field of view of the imaging system  204  after it has been moved in correspondence with the detected head movement  211 . 
     At a process  312 , an image of the surgical environment from the changed field of view is displayed on the display system. For example, with reference to  FIG.  10   , the image  215   a  of the field of view  206  on the display system  203  is changed to an image  215   b  of field of view  207 . 
     When the teleoperational system is in the imaging control mode, movement of the hand controllers  18  may cause movement of the instrument  204  within the range of motion and may consequently change the field of view of the instrument  204 . Alternatively, movement of the hand controllers  18  may cause ghosted images of the surgical instruments in the field of view to move in accordance with the movement of the controllers. 
     If the detected motion of the user&#39;s head does not correspond to a movement within the range of motion of the imaging instrument, the teleoperational system may enter the virtual explore mode and provide images of other environments, user interfaces, or information and previously described. The virtual explore mode may be exited by matching the user&#39;s head with the last position and orientation of the imaging system, as previously described. 
     The imaging control mode may be exited when an additional imaging control input (e.g., depressing a button on the controller  18 ) is detected. In various alternative embodiments, the imaging control mode may require continuous activation of the imaging control input (e.g., continuous depression of a button on the controller  18 ) such that discontinuing the control input transitions the teleoperational system from imaging control mode into an engagement or following mode. 
     The teleoperational system may be constrained to provide a virtual manipulator arm mode that indicates when a user&#39;s arm motion is outside of a range of motion that corresponds to an allowable range of motion of the manipulator arm (e.g., arm  12 ).  FIG.  11    is a flowchart  400  providing a method for entering and operating within a virtual manipulator arm mode of a teleoperational system. The teleoperational surgical system may be, for example a teleoperational surgical system  11  for use in a live surgical environment  10  or a simulator environment  40 . The method  400  is illustrated in  FIG.  11    as a set of operations or processes  402  through  408 . Not all of the illustrated processes  402  through  408  may be performed in all embodiments of method  400 . Additionally, one or more processes that are not expressly illustrated in  FIG.  11    may be included before, after, in between, or as part of the processes  402  through  408 . In some embodiments, one or more of the processes may be implemented, at least in part, in the form of executable code stored on non-transitory, tangible, machine-readable media that when run by one or more processors (e.g., the processors of control system) may cause the one or more processors to perform one or more of the processes. 
     At a process  402 , an image of a surgical environment is displayed. The image is displayed on a user-mounted immersive display system. The surgical environment image may include an images of a surgical instrument and/or portions of a manipulator arm to which the instrument is coupled. 
     At a process  404 , a manipulator arm input motion is detected. For example movement of a user&#39;s arm or hand may be detected as a manipulator arm input motion. At a process  406 , the teleoperational system determines if the manipulator arm input motion corresponds to movement outside of the physical manipulator arm (e.g. arm  12 ) range of motion. If the input motion corresponds to movement of the manipulator am outside of the range of motion, the teleoperational system enters a virtual manipulator arm mode. In the virtual manipulator arm mode, movement of the user&#39;s arm does not cause corresponding motion of the physical manipulator arm and a ghost image of the surgical instrument or a ghost image of the manipulator arm is shown moving on the display system with motion corresponding to the manipulator arm input motion. To exit the virtual manipulator arm mode, the user may be directed back to the last allowable position of the surgical instrument or manipulator arm. The directions back to the matched position may be similar to those provided to the user to exit the virtual explore mode as previously described. 
     While certain exemplary embodiments of the invention have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention. Additionally, it is to be understood that the embodiments of the invention are not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art. 
     Further, in the detailed description of the embodiments of the invention, numerous specific details have been set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be obvious to one skilled in the art that the embodiments of this disclosure may be practiced without these specific details. In some instances, well known methods, procedures, and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments of the invention.