Patent Description:
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. Some minimally invasive medical instruments may be teleoperated or otherwise computer-assisted. A variety of control devices may be used to control teleoperated or computer-assisted medical tools. To extend the functionality of teleoperated systems without adding additional structural controls to the user's control console, graphical user interfaces may be used. Systems and methods are provide haptic feedback to the user when accessing graphical user interfaces using control devices that are also used to control instruments in the patient anatomy.

<CIT> discloses a system to control the interaction between a user-interface of a teleoperated surgical system and an input device of the teleoperated surgical system. The system comprising a first master controller communicatively coupled to the teleoperated surgical system, a feedback control communicatively coupled to the first master controller, and a display device communicatively coupled to the teleoperated surgical system and configured to display the user interface. The feedback control is configured to restrict the movement of the first master controller based on a state of the user interface changing from a previous state. <CIT> discloses a system for controlling a user interface of a teleoperated surgical system. The system comprises a first master controller communicatively coupled to the teleoperated surgical system; and a display device communicatively coupled to the teleoperated surgical system and configured to display a graphical user interface. The first master controller is configured to transmit a first input signal to an interface controller, the first input signal caused by manual manipulation of the first master controller, the interface controller to use the first input signal to update a graphical user interface presented by the display device.

The embodiments of the invention are summarized by the claims that follow below.

In an embodiment, a haptic feedback method comprises engaging an interface mode of a teleoperational control system. Responsive to movement of a control device of the teleoperational control system, the method further comprises, from a nominal position, applying a first haptic force to the control device urging the control device toward the nominal position. The method also includes determining that the control device has moved, from a nominal position, a first displacement distance in a first degree of freedom to an engaged position. The method also includes applying a second haptic force to the control device to provide a haptic sensation indicative of an engaged operational state. The method also includes applying a third haptic force to the control device to urge a return of the control device from the engaged position toward the nominal position while in the engaged operational state.

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).

Referring to <FIG> of the drawings, a teleoperational medical system for use in, for example, medical procedures including diagnostic, therapeutic, or surgical procedures, is generally indicated by the reference numeral <NUM>. As will be described, the teleoperational medical systems of this disclosure are under the teleoperational control of a surgeon. In alternative embodiments, a teleoperational medical system may be under the partial control of a computer programmed to perform the procedure or sub-procedure. In still other alternative embodiments, a fully automated medical system, under the full control of a computer programmed to perform the procedure or sub-procedure, may be used to perform procedures or sub-procedures. As shown in <FIG>, the teleoperational medical system <NUM> generally includes a teleoperational assembly <NUM> mounted to or near an operating table O on which a patient P is positioned. The teleoperational assembly <NUM> may be referred to as a patient side cart. A medical instrument system <NUM> and an endoscopic imaging system <NUM> are operably coupled to the teleoperational assembly <NUM>. An operator input system <NUM> allows a surgeon or other type of clinician S to view images of or representing the surgical site and to control the operation of the medical instrument system <NUM> and/or the endoscopic imaging system <NUM>.

The operator input system <NUM> may be located at a surgeon's console, which is usually located in the same room as operating table O. It should be understood, however, that the surgeon S can be located in a different room or a completely different building from the patient P. Operator input system <NUM> generally includes one or more control device(s) for controlling the medical instrument system <NUM>. The control device(s) may include one or more of any number of a variety of input devices, such as hand grips, joysticks, trackballs, data gloves, trigger-guns, hand-operated controllers, voice recognition devices, touch screens, body motion or presence sensors, and the like. In some embodiments, the control device(s) 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 control device(s) may have more or fewer degrees of freedom than the associated medical instruments and still provide the surgeon with telepresence. In some embodiments, the control device(s) are manual input devices which move with six degrees of freedom, and which may also include an actuatable handle for actuating instruments (for example, for closing grasping jaws, applying an electrical potential to an electrode, delivering a medicinal treatment, and the like).

The teleoperational assembly <NUM> supports and manipulates the medical instrument system <NUM> while the surgeon S views the surgical site through the console <NUM>. An image of the surgical site can be obtained by the endoscopic imaging system <NUM>, such as a stereoscopic endoscope, which can be manipulated by the teleoperational assembly <NUM> to orient the endoscope <NUM>. An electronics cart <NUM> can be used to process the images of the surgical site for subsequent display to the surgeon S through the surgeon's console <NUM>. The number of medical instrument systems <NUM> used at one time will generally depend on the diagnostic or surgical procedure and the space constraints within the operating room among other factors. The teleoperational assembly <NUM> may include a kinematic structure of one or more non-servo controlled links (e.g., one or more links that may be manually positioned and locked in place, generally referred to as a set-up structure) and a teleoperational manipulator. The teleoperational assembly <NUM> includes a plurality of motors that drive inputs on the medical instrument system <NUM>. These motors move in response to commands from the control system (e.g., control system <NUM>). The motors include drive systems which when coupled to the medical instrument system <NUM> may advance the medical instrument into a naturally or surgically created anatomical orifice. Other motorized drive systems may move the distal end of the medical instrument in multiple degrees of freedom, which may include three degrees of linear motion (e.g., linear motion along the X, Y, Z axes of a Cartesian reference frame) 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. Electric motors can be controlled to generate a commanded torque (or force, in the case of a linear motor).

The teleoperational medical system <NUM> also includes a control system <NUM>. The control system <NUM> includes at least one memory and at least one processor (not shown), and typically a plurality of processors, for effecting control between the medical instrument system <NUM>, the operator input system <NUM>, and an electronics system <NUM>. The control system <NUM> 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 <NUM> is shown as a single block in the simplified schematic of <FIG>, 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 <NUM>, another portion of the processing being performed at the operator input system <NUM>, and the like. Any of a wide variety of centralized or distributed data processing architectures may be employed. 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 <NUM> supports wireless communication protocols such as Bluetooth, IrDA, HomeRF, IEEE <NUM>, DECT, and Wireless Telemetry.

In some embodiments, control system <NUM> may include one or more servo controllers that receive force and/or torque feedback from the medical instrument system <NUM>. Responsive to the feedback, the servo controllers transmit signals to the operator input system <NUM>. The servo controller(s) may also transmit signals instructing teleoperational assembly <NUM> to move the medical instrument system(s) <NUM> and/ or endoscopic imaging system <NUM> 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 <NUM>. In some embodiments, the servo controller and teleoperational assembly are provided as part of a teleoperational arm cart positioned adjacent to the patient's body.

The teleoperational medical system <NUM> may further include optional operation and support systems (not shown) such as illumination systems, steering control systems, irrigation systems, and/or suction systems. In alternative embodiments, the teleoperational system may include more than one teleoperational assembly and/or more than one operator input system. The exact number of manipulator assemblies will depend on the surgical procedure and the space constraints within the operating room, among other factors. The operator input systems may be collocated, or they may be positioned in separate locations. Multiple operator input systems allow more than one operator to control one or more manipulator assemblies in various combinations.

<FIG> is a perspective view of the surgeon's console <NUM>. The surgeon's console <NUM> includes a left eye display <NUM> and a right eye display <NUM> for presenting the surgeon S with a coordinated stereo view of the surgical site that enables depth perception. The console <NUM> further includes one or more input control devices <NUM>, <NUM> which are used by the surgeon to execute functions of the system <NUM>. The input control devices <NUM> are hand operated input control devices which cause the teleoperational assembly <NUM> to manipulate one or more instruments or the endoscopic imaging system. The input control devices <NUM> can provide the same degrees of freedom as their associated instruments <NUM> to provide the surgeon S with telepresence, or the perception that the input control devices <NUM> are integral with the instruments <NUM> so that the surgeon has a strong sense of directly controlling the instruments <NUM>. To this end, position, force, and tactile feedback sensors (not shown) may be employed to transmit position, force, and tactile sensations from the instruments <NUM> back to the surgeon's hands through the input control devices <NUM>. The input control devices <NUM> allow the system <NUM> to shift between operational modes. The devices <NUM> may be pedals operated by the surgeon's foot or may be other types of hand or foot switches that serve as a clutch device to disengage a first operational mode and engage a second operational control mode. Operational modes of the teleoperational medical system <NUM> may include, for example, a surgical instrument control mode, a camera control mode, a menu control mode, and the like. A surgical instrument control mode may allow the surgeon to control manipulation of the instruments <NUM> as described above. A camera control mode may allow the surgeon to use the input control devices <NUM> to cause the teleoperational assembly <NUM> to manipulate the endoscopic imaging system <NUM>. A menu control mode may allow the surgeon to use input control devices <NUM> to navigate a graphical user interface menu displayed to the surgeon via left and right eye displays <NUM> and <NUM>. The control device <NUM> may be depressed, for example, to transition between the surgical instrument control mode and the menu mode.

<FIG> is a perspective view of the electronics cart <NUM>. The electronics cart <NUM> can be coupled with the endoscope <NUM> and can include a processor to process captured images for subsequent display, such as to a surgeon on the surgeon's console, or on another suitable display located locally and/or remotely. For example, where a stereoscopic endoscope is used, the electronics cart <NUM> 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 another example, image processing can include the use of previously determined camera calibration parameters to compensate for imaging errors of the image capture device, such as optical aberrations. The electronics cart <NUM> may also include a display monitor and components of the control system <NUM>.

<FIG> is a perspective view of one embodiment of a teleoperational assembly <NUM> which may be referred to as a patient side cart. The patient side cart <NUM> shown provides for the manipulation of three surgical tools <NUM> (e.g., instrument systems <NUM>) and an imaging device <NUM> (e.g., endoscopic imaging system <NUM>), such as a stereoscopic endoscope used for the capture of images of the site of the procedure. The imaging device may transmit signals over a cable <NUM> to the electronics cart <NUM>. Manipulation is provided by teleoperative mechanisms having a number of joints. The imaging device <NUM> and the surgical tools <NUM> can be positioned and manipulated through incisions in the patient so that a kinematic remote center is maintained at the incision to minimize the size of the incision. Images of the surgical site can include images of the distal ends of the surgical tools <NUM> when they are positioned within the field-of view of the imaging device <NUM>.

The patient side cart <NUM> includes a drivable base <NUM>. The drivable base <NUM> is connected to a telescoping column <NUM>, which allows for adjustment of the height of the arms <NUM>. The arms <NUM> may include a rotating j oint <NUM> that both rotates and moves up and down. Each of the arms <NUM> may be connected to an orienting platform <NUM>. The orienting platform <NUM> may be capable of <NUM> degrees of rotation. The patient side cart <NUM> may also include a telescoping horizontal cantilever <NUM> for moving the orienting platform <NUM> in a horizontal direction.

In the present example, each of the arms <NUM> connects to a manipulator arm <NUM>. The manipulator arms <NUM> may connect directly to a medical instrument <NUM>. The manipulator arms <NUM> may be teleoperatable. In some examples, the arms <NUM> connecting to the orienting platform are not teleoperatable. Rather, such arms <NUM> are positioned as desired before the surgeon <NUM> begins operation with the teleoperative components.

Endoscopic imaging systems (e.g., systems <NUM>, <NUM>) may be provided in a variety of configurations including rigid or flexible endoscopes. Rigid endoscopes include a rigid tube housing a relay lens system for transmitting an image from a distal end to a proximal end of the endoscope. Flexible endoscopes transmit images using one or more flexible optical fibers. Endoscopes may be provided with different viewing angles including a <NUM>° viewing angle for forward axial viewing or viewing angles between <NUM>°-<NUM>° for forward oblique viewing. Digital image based endoscopes have a "chip on the tip" design in which a distal digital sensor such as a one or more charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device store image data. Endoscopic imaging systems may provide two- or three-dimensional images to the viewer. Two-dimensional images may provide limited depth perception. Three-dimensional stereo endoscopic images may provide the viewer with more accurate depth perception. Stereo endoscopic instruments employ stereo cameras to capture stereo images of the patient anatomy.

In order to extend the functionality of the teleoperational medical system <NUM> without adding additional structural appendages, such as foot pedals, physical switches, dials, and buttons to the control console <NUM>, graphical user interface menus may be used to provide additional options and actions for operating the system <NUM>. When using graphical user interface menus to offer additional functions of the system <NUM>, it is helpful to provide haptic feedback to the operator at the control console <NUM> to facilitate interaction with the elements of the graphical user interface menu and to provide confirmation that commands have been executed. Other feedback mechanisms such as auditory and visual feedback cues may also provide confirmation that commands have been executed. The use of haptic feedback when using graphical interface menus may provide a sense of immersion for the user.

<FIG> illustrates a display <NUM> visible through the left eye display <NUM> and the right eye display <NUM> of the surgeon's console <NUM>. In this embodiment, the display include a view of the surgical environment <NUM> including medical tools <NUM>, <NUM>, <NUM>. In surgical instrument control or "following" operational mode of the teleoperational system, the control devices <NUM> may be manipulated to control movement of the tools <NUM>, <NUM>, <NUM> in limited or unlimited degrees of freedom. For example, in the surgical instrument control mode, the control devices may be operable to move the instruments only in three degrees of translational freedom in Cartesian coordinate space. When a graphical user interface mode of the teleoperational system is invoked (e.g., by depressing a clutch pedal <NUM>), the control devices <NUM> become decoupled from the tools <NUM>, <NUM>, <NUM> and can instead be used to select items from a graphical user interface menu. <FIG> illustrates a graphical user interface menu including a selector icon <NUM> and a plurality of menu items <NUM>, <NUM>, <NUM>. The graphical user interface menu <NUM> may be superimposed on the image of the surgical environment <NUM> as shown in <FIG> or alternatively, only the graphical user interface menu may be displayed, without the surgical environment. In the graphical user interface mode with the tools <NUM>, <NUM>, <NUM> uncoupled from the control devices <NUM>, one or more of the control devices may be coupled to move the selector icon <NUM> between a nominal or neutral position (as shown in <FIG>) and the menu items <NUM>, <NUM>, <NUM>. In one embodiment, menu item <NUM> may be associated with an endoscopic camera control mode in which the camera may be repositioned.

<FIG> illustrates the selector icon <NUM> of <FIG> in a nominal position and having a clockwise direction of movement that corresponds to clockwise movement of a control device <NUM> about the rotational axis of the control device. The nominal position of the control device <NUM> may be located in space wherever the control device was positioned and oriented when the graphical user interface mode was engaged. Thus, the location of the nominal position of the control device <NUM> in space may be different each time the interface mode is engaged.

Movement of the selector icon <NUM> may be coupled to the right or left hand control device. Different graphical user interface menus maybe associated with each hand so that the right hand selects from a first menu and the left hand selects from a second menu. The menu may, alternatively, be configured so that the menu items are selected by counter-clockwise rotation. The rotational movement of the control device <NUM> used to move the selector icon <NUM> may be a degree of freedom that is not used to operate the tools when the system in other modes of operation such as the surgical instrument control mode. Thus, the user recognizes that the roll degree of freedom about the axis of the control device is used for menu selection and not tool operation. In other embodiments, the same degrees of freedom used to control the selector icon may be used to control tool movement in the surgical instrument control mode. In other embodiments, the control device may move in both clockwise and counterclockwise directions to select menu items. For example, clockwise rotation may direct the selector icon toward a menu item for "Active Camera Control Action" and a counter-clockwise rotation may direct the selector icon toward a menu item for an "Active Relocate" action. In other embodiments, the control device may move about other rotational axes or may translate along axes to generate the selection motion. In other words, any Cartesian translational or rotational motion may generate the selection motion.

Referring now to <FIG>, a flowchart <NUM> illustrates a method of providing haptic feedback through a control device of a teleoperational system, such as system <NUM>, when using a graphical user interface menu, such as the menu <NUM>. Prior to initiating the process shown in flowchart <NUM>, the system <NUM> may be in a surgical instrument control mode or another operational mode of the system. At a process <NUM>, the control system <NUM> determines whether an input control device <NUM> has been actuated to initiate a graphical user interface mode of the system <NUM>. This mode may be enabled, for example, by depressing a clutch pedal <NUM> of the surgeon's console to disengage from the surgical instrument control mode, including decoupling the surgical instruments from the control devices <NUM>, and engaging the graphical user interface control mode, including coupling at least one of the control devices to a graphical user interface menu selector icon. At a process <NUM>, the menu <NUM> is displayed either with or without the image of the surgical environment. If, for example, the menu <NUM> is associated with an instrument visible in the surgical environment, the menu may appear near a distal tip of that instrument.

At a process <NUM>, the system <NUM> receiving and tracking control signals from the control device <NUM> indicating that the control device is being moved in a clockwise direction about the axis of the shaft of the control device. Accordingly, the selector icon <NUM> moves counterclockwise from a nominal position N (see <FIG>) toward menu item A as shown in <FIG>.

At a process <NUM>, a haptic force such as a haptic torque is provided to the control device when the instrument control device is moved a threshold displacement distance associated with a selection position corresponding to the menu item A <NUM>. The haptic torque may be superimposed on the normal torque produced by the controller. The haptic torque provides a haptic detent or sensation to the user indicating that the controller has selected the menu item A. The normal torque may be, for example, a torque generated to reflect to the user a tracking error that the teleoperational assembly has with respect to the control device position/ orientation.

At a process <NUM>, a command associated with the menu item A is executed in response to a user input (e.g., pressing a physical button on the control device). For example the menu item A may initiate camera control. Alternatively, and particularly if there is a single menu item, the execution of the command may occur when the control device reaches the selected position. Optionally, the selector icon <NUM> and the control device <NUM> may remain in the selected position, awaiting further movement of the control device to move the selector icon clockwise to menu item B <NUM> or counter-clockwise to the nominal position.

At a process <NUM>, according to the invention, another haptic torque may be provided to move the control device <NUM> and the selector icon <NUM> back to the nominal position after the command for menu item A is executed at process <NUM> (see <FIG>). With this technique of re-centering the selector icon and control device <NUM> to a nominal position, a counter module may be used to count each time the selector icon and control device <NUM> return to the nominal position from the selection position. In this embodiment, a counter value of the counter module is incremented each time the selector icon and control device <NUM> return to the nominal position from the selection position. Each count increment of the counter module may be associated with a menu item, allowing the user to toggle through a items in a menu with repeated reciprocal movements of the control device <NUM>. For example, one click (e.g., one count of movement to the selection position and a return to the nominal position) may correspond to a first menu item and two clicks may correspond to a second menu item. The incremented menu items may be displayed to the user. Using the counter module requires the user to rotate the control device only a limited distance (e.g. to menu item A) to toggle through several menu items rather than requiring the user to rotate the control device far away from the nominal position. This prevents the user from contorting his hand to reach large angle positions and allows the user's hand to always be close to the nominal position where he can quickly change modes and resume control of the surgical instruments coupled to the control devices <NUM>.

<FIG> illustrates an alternative graphical user interface menu <NUM> in which a selector icon <NUM> moves in a translational direction. Other menu arrangements in which the control device and the selector icon move in other single degrees of freedom may be used.

In an alternative embodiment, either a clockwise motion of the control device <NUM> or a counter-clockwise motion of the control device may result in movement of the selector icon <NUM> in a clock-wise direction or may result in movement of the selector icon <NUM> in a single translational direction. In other words, a motion of the control device <NUM> in either the right or the left roll direction would result in the same single advancement of the selector icon. A haptic detent feature or "click" may be felt by the user for each single movement. This embodiment may be suitable for making the movement action easily accessible in multiple postures of the control device <NUM>. For example, when the control device <NUM> is pointing to the right, it may be easier for the user to twist the roll axis of the control device to the left rather than the right to advance the selector icon. By making the movement action symmetric (i.e., such that either control device can cause the selector advancement), the user has more options for controlling the selector. This feature may be simultaneously active on both right and left control devices. The software may detect which control device crosses the δ<NUM> threshold to determine which control device is activating the haptic detent feature.

<FIG> illustrates a haptic detent torque profile TS superimposed on a controller torque profile TC used to provide haptic feedback to the control device <NUM> according to an embodiment in which applied motor torque mimics a rotational spring-loaded button. In this embodiment, the haptic detent torque profile TS creates the haptic sensation of a spring-loaded button. <FIG> is a flow chart <NUM> describing the torque profile of <FIG>. The torque profiles are provided to one or more drive actuators in the control device <NUM> to provide a force feedback felt by the hands of the surgeon S. The controller torque profile TC provides a centering or force that urges the control device toward the nominal position. Greater torque is applied as the displacement δ (e.g., angle of rotation or distance of rotation of the control device <NUM>) increases, and the hand of the surgeon on the control device feels increasing resistance of the control device as the displacement δ increases. The nominal position is located where a displacement δ equals zero. The haptic detent torque profile TS superimposed on the controller torque profile TC has several zones.

With reference to <FIG> and <FIG>, at a process <NUM>, when the control device has a displacement (from nominal) within a displacement zone between zero and δ<NUM>, a torque profile T<NUM> follows the controller torque profile TC, providing no additional resistance torque beyond the torque profile TC. At a process <NUM> when the control device has a displacement in a displacement zone between δ<NUM> and δ<NUM>, a torque profile T<NUM> has a steep negative slope away from the torque profile TC. That is, the resistive force experienced by the surgeon decreases suddenly. At a process <NUM> when the control device has a displacement in a displacement zone between δ<NUM> and δ<NUM>, a torque profile T<NUM> has a torque sign inversion that provides a force that urges the control device away from the nominal position and toward a displacement distance δ<NUM>. The torque profile T<NUM> provides the haptic sensation of a sharp push toward the button "click" or engaged point that occurs at the displacement distance δ<NUM>. At a process <NUM> once the control device has reached a displacement distance δ<NUM>, a torque profile T<NUM> provides a centering (toward nominal) force that is smaller than the torque profile TC at the same displacement distance. As shown in <FIG>, the torque profiles TC and TS have symmetric profiles representing two "button" torque profiles. The symmetric torque profile may provide the same haptic detent sensation but may occur when the rotational motion of the control device is in the opposite direction. In alternative embodiments, the calculated torque profiles may change at different displacements associated with locations of different menu items and the magnitude of the torque provided may be increased or lessened depending a variety of factors including user preference, the user grip action associated with the detent magnitude, or the time expected between successive actions.

<FIG> illustrates a haptic detent torque profile TE superimposed on a controller torque profile TC used to provide haptic feedback to the control device <NUM> after the engaged or "clicked" displacement distance δ<NUM> is reached. In this embodiment, the haptic detent torque profile TE creates the haptic sensation of an engaged or "clicked" spring-loaded button and a haptic sensation of a recentering detent. <NUM> is a flow chart <NUM> describing the torque profile of <FIG>. Once the control device <NUM> has reached a displacement distance δ<NUM>, the torque profile T<NUM> provides a centering (toward nominal) force that is smaller than the torque profile TC at the same displacement distance. The torque profile T<NUM> is followed until the control device reaches a displacement distance δ<NUM> on the return to the nominal position. At a process <NUM>, when the control device reaches a displacement distance δ<NUM>, a torque profile T<NUM> provides an increased torque to the level of the controller torque profile TC. When the torque profile T5 is applied to the control device, the user feels a sudden increased resistance over T4. The sudden increase in resistance may cause the user to instinctively relax or release his grip, allowing the control device to re-center to the nominal position where displacement δ equals zero at a process <NUM>.

In one alternative embodiment, the torque superimposed on the normal control device torque mimics a translational switch that provide ON and OFF switch positions at displacement distances along a line in space. In another alternative embodiment, the torque superimposed on the normal control device torque mimics a rotational switch that provides ON and OFF switch positions at angular displacement distances about an axis in space. This embodiment may be similar to the button embodiment described in detail above except without providing a re-centering force to move the control device toward the nominal position. Instead, the control device remains in the selected position (i.e. "clicked state") until the action is executed, at which point the detent is deactivated or reset. In another alternative embodiment, the torque superimposed on the normal control device torque mimics a spring-loaded translational button with movement along a line in space.

One or more elements in embodiments of the invention may be implemented in software to execute on a processor of a computer system such as control processing system. When implemented in software, the elements of the embodiments of the invention are essentially the code segments to perform the necessary tasks. The program or code segments can be stored in a processor readable storage medium or device that may have been downloaded by way of a computer data signal embodied in a carrier wave over a transmission medium or a communication link. The processor readable storage device may include any medium that can store information including an optical medium, semiconductor medium, and magnetic medium. Processor readable storage device examples include an electronic circuit; a semiconductor device, a semiconductor memory device, a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM); a floppy diskette, a CD-ROM, an optical disk, a hard disk, or other storage device, The code segments may be downloaded via computer networks such as the Internet, Intranet, etc..

Claim 1:
A haptic feedback method comprising:
engaging (<NUM>) an interface mode of a teleoperational control system;
responsive to movement of a control device of the teleoperational control system, from a nominal position, applying a first haptic force to the control device urging the control device toward the nominal position;
determining that the control device has moved, from the nominal position, a first displacement distance in a first degree of freedom to an engaged position;
characterized in further comprising:
applying (<NUM>) a second haptic force to the control device to provide a haptic sensation indicative of an engaged operational state; and
applying (<NUM>) a third haptic force to the control device to urge a return of the control device from the engaged position toward the nominal position while in the engaged operational state.