Phantom degrees of freedom in joint estimation and control

Methods, apparatus, and systems for operating a surgical system. In accordance with a method, a position of a surgical instrument is measured, the surgical instrument being included in a mechanical assembly having a plurality of joints and a first number of degrees of freedom, the position of the surgical instrument being measured for each of a second number of degrees of freedom of the surgical instrument. The method further includes estimating a position of each of the joints, where estimating the position of each joint includes applying the position measurements to at least one kinematic model of the mechanical assembly, the kinematic model having a third number of degrees of freedom greater than the first number of degrees of freedom. The method further includes controlling the mechanical assembly based on the estimated position of the joints.

BACKGROUND

Embodiments of the present invention generally provide improved surgical and/or robotic devices, systems, and methods.

Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue which is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. Millions of surgeries are performed each year in the United States. Many of these surgeries can potentially be performed in a minimally invasive manner. However, only a relatively small number of surgeries currently use these techniques due to limitations in minimally invasive surgical instruments and techniques and the additional surgical training required to master them.

Minimally invasive telesurgical systems for use in surgery are being developed to increase a surgeon's dexterity as well as to allow a surgeon to operate on a patient from a remote location. Telesurgery is a general term for surgical systems where the surgeon uses some form of remote control, e.g., a servomechanism, or the like, to manipulate surgical instrument movements rather than directly holding and moving the instruments by hand. In such a telesurgery system, the surgeon is provided with an image of the surgical site at the remote location. While viewing typically a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master control input devices, which in turn control the motion of robotic instruments. The robotic surgical instruments can be inserted through small, minimally invasive surgical apertures to treat tissues at surgical sites within the patient, such apertures resulting in the trauma typically associated with open surgery. These robotic systems can move the working ends of the surgical instruments with sufficient dexterity to perform quite intricate surgical tasks, often by pivoting shafts of the instruments at the minimally invasive aperture, sliding of the shaft axially through the aperture, rotating of the shaft within the aperture, and/or the like.

The servomechanism used for telesurgery will often accept input from two master controllers (one for each of the surgeon's hands) and may include two or more robotic arms or manipulators. Mapping of the hand movements to the image of the robotic instruments displayed by the image capture device can help provide the surgeon with accurate control over the instruments associated with each hand. In many surgical robotic systems, one or more additional robotic manipulator arms are included for moving an endoscope or other image capture device, additional surgical instruments, or the like.

A variety of structural arrangements can be used to support the surgical instrument at the surgical site during robotic surgery. The driven linkage or “slave” is often called a robotic surgical manipulator, and exemplary linkage arrangements for use as a robotic surgical manipulator during minimally invasive robotic surgery are described in U.S. Provisional Application No. 61/654,764 filed Jun. 1, 2012, entitled “Commanded Reconfiguration of a Surgical Manipulator Using the Null Space”, and U.S. Pat. Nos. 6,758,843; 6,246,200; and 5,800,423, the full disclosures of which are incorporated herein by reference in their entirety. These linkages often make use of a parallelogram arrangement to hold an instrument having a shaft. Such a manipulator structure can constrain movement of the instrument so that the instrument shaft pivots about a remote center of spherical rotation positioned in space along the length of the rigid shaft. By aligning this center of rotation with the incision point to the internal surgical site (for example, with a trocar or cannula at an abdominal wall during laparoscopic surgery), an end effector of the surgical instrument can be positioned safely by moving the proximal end of the shaft using the manipulator linkage without imposing dangerous forces against the abdominal wall. Alternative manipulator structures are described, for example, in U.S. Pat. Nos. 7,594,912, 6,702,805; 6,676,669; 5,855,583; 5,808,665; 5,445,166; and 5,184,601, the full disclosures of which are incorporated herein by reference in their entirety.

While the new robotic surgical systems and devices have proven highly effective and advantageous, still further improvements would be desirable. In some cases, the master controller(s) used by the surgeon have a number of degrees of freedom more than or equal to the number of degrees of freedom which the end effectors of the remotely controlled robotic manipulator arms and/or tools have. In such cases, controllers that are used to control the robotic manipulator arms and/or tools may become overconstrained. For example, where the remote tool is a rigid endoscope extending through a minimally invasive aperture, two orientational degrees of freedom may not be available within the workspace (those associated with a tool wrist near an end effector, e.g., wrist pitch and yaw). Accordingly, the robotic manipulator with endoscope only has four degrees of freedom at its tip. In practice, these mathematical problems can become tangible, resulting in a sluggish, unresponsive feel to the surgeon which is undesirable. Further problems can arise when tools having different degrees of freedom are used with the same robotic surgical manipulator. For example, a surgeon may wish to use jaws having three degrees of freedom, and then replace the jaws with a suction device having two degree of freedom. Even further problems can arise when using estimated joint positions to control tool movements in situations where input and output degrees of freedom differ. Such situations may result in numerical errors being imposed into the joint position estimations resulting in undesired tool movements.

For these and other reasons, it would be advantageous to provide improved devices, systems, and methods for surgery, robotic surgery, and other robotic applications. It would be particularly beneficial if these improved technologies provided the ability to effectively control robotic manipulator arms and/or tools with end effectors having a number of degrees of freedom fewer than the number of degrees of freedom of a master controller manipulated by a surgeon. It would be even more beneficial if these improved technologies allowed the same computation engine to be used for all instruments of the robotic system, thereby reducing controller complexity and costs while increasing flexibility.

BRIEF SUMMARY

Embodiments of the present invention generally provide improved robotic and/or surgical devices, systems, and methods. In one embodiment, a method of operating a surgical system is disclosed. The method includes various operations, including measuring a position of a surgical instrument. The surgical instrument is included in a mechanical assembly having a plurality of joints, and the position of the surgical instrument is measured for each of a first number of degrees of freedom of the surgical instrument. The method further includes estimating a position of each of the joints, where estimating the position of each joint includes applying the position measurements to at least one kinematic model of the mechanical assembly. The kinematic model has a second number of degrees of freedom greater than the first number of degrees of freedom. The method further includes controlling the mechanical assembly based on the estimated position of the joints.

In accordance with another embodiment, a surgical system for performing minimally invasive surgery through an aperture of a patient is disclosed. The system includes a robotic manipulator assembly including a surgical tool. The robotic manipulator assembly has a plurality of joints, and is operable to position the surgical tool at the aperture of the patient. The system further includes a tool position measuring device operable to measure a position of the surgical tool for each of a first number of degrees of freedom of the surgical tool. The system also includes a controller. The controller is operable to perform a variety of functions. For example, the controller is operable to estimate a position of each of the joints, where estimating the position of each joint includes applying the position measurements to a kinematic model of the robotic manipulator assembly. The kinematic model has a second number of degrees of freedom greater than the first number of degrees of freedom. The controller is further operable to control the robotic manipulator assembly based on the estimated position of the joints.

In accordance with yet another embodiment, method for controlling the movement of a mechanical body is disclosed. The method includes receiving control information for controlling the position of a mechanical body. The mechanical body has a first number of degrees of freedom. The method also includes generating a plurality of individual control outputs by applying the received control information to a kinematic model. The kinematic model has a second number of degrees of freedom greater than the first number of degrees of freedom. Each of the individual control outputs are configured to affect control of a corresponding one of the second number of degrees of freedom. The method further includes transmitting a subset of the plurality of individual control outputs for use in controlling the first number of degrees of freedom of the mechanical body.

For a fuller understanding of the nature and advantages of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. Other aspects, objects and advantages of the invention will be apparent from the drawings and detailed description that follows.

DETAILED DESCRIPTION

Embodiments of the present invention generally provide improved techniques for controlling the movement of mechanical bodies. Some embodiments are particularly advantageous for use with surgical robotic systems in which a plurality of surgical tools or instruments are mounted on and moved by an associated plurality of robotic manipulators during a surgical procedure. The robotic systems will often comprise telerobotic, telesurgical, and/or telepresence systems that include processors configured as master-slave controllers. By providing robotic systems employing processors appropriately configured to move manipulator assemblies with articulated linkages having relatively large numbers of degrees of freedom, the motion of the linkages can be tailored for work through a minimally invasive access site.

The robotic manipulator assemblies described herein will often include a robotic manipulator and a tool mounted thereon (the tool often comprising a surgical instrument in surgical versions), although the term “robotic assembly” will also encompass the manipulator without the tool mounted thereon. The term “tool” encompasses both general or industrial robotic tools and specialized robotic surgical instruments, with these later structures often including an end effector which is suitable for manipulation of tissue, treatment of tissue, imaging of tissue, or the like. The tool/manipulator interface will often be a quick disconnect tool holder or coupling, allowing rapid removal and replacement of the tool with an alternate tool. The manipulator assembly will often have a base which is fixed in space during at least a portion of a robotic procedure, and the manipulator assembly may include a number of degrees of freedom between the base and an end effector of the tool. For example, the manipulator assembly may include kinematic degrees of freedom of a manipulator as well as kinematic degrees of freedom of a tool connected to the manipulator. The combination of these may be referred to herein as “manipulator degrees of freedom”, and are typically defined in joint space (described below). Actuation of the end effector (such as opening or closing of the jaws of a gripping device, energizing an electrosurgical paddle, activating air pressure for a vacuum, or the like) will often be separate from, and in addition to, these manipulator assembly degrees of freedom. These may be referred to herein as “actuation degrees of freedom”.

The end effector (or, more generally, the control frame, as described below) will typically move in the workspace with between two and six degrees of freedom. The degrees of freedom of the end effector (or, more generally, the degrees of freedom of the control frame) may be referred to herein as “end effector degrees of freedom”, and are typically defined in Cartesian space (described below). As used herein, the term “position” encompasses both location and orientation. Hence, a change in a position of an end effector (for example) may involve a translation of the end effector from a first location to a second location, a rotation of the end effector from a first orientation to a second orientation, or a combination of both. When used for minimally invasive robotic surgery, movement of the manipulator assembly may be controlled by a processor of the system so that a shaft or intermediate portion of the tool or instrument is constrained to a safe motion through a minimally invasive surgical access site or other aperture. Such motion may include, for example, axial insertion of the shaft through the aperture site into a surgical workspace, rotation of the shaft about its axis, and pivotal motion of the shaft about a pivot point at the aperture site.

Many of the manipulator assemblies described herein have fewer degrees of freedom available for use than those that are typically associated with full control over the positioning of an end effector in a workspace (where full control of the end effector requires end effector degrees of freedom including three independent translations and three independent orientations). That is, the manipulator assemblies may have an insufficient number or type of degrees of freedom for independently controlling the six end effector degrees of freedom. For example, a rigid endoscope tip without an articulating wrist may be missing one or two degrees of freedom at the wrist, such as wrist pitch and/or yaw. Accordingly, the endoscope may have only four or five degrees of freedom for positioning the end effector, rather than six, thus potentially constraining the motion of the endoscope.

However, some of the manipulator assemblies described herein have a greater number of degrees of freedom than that required to fully control the positioning of the end effector (where full control of the end effector requires end effector degrees of freedom including three independent translations and three independent orientations), but due to the type or arrangement of the joints of the manipulator assemblies, the manipulator assemblies still cannot fully control the positioning of the end effector. For example, a manipulator assembly may have seven manipulator degrees of freedom, but three of those are redundant. As a result, the end effector effectively has five degrees of freedom.

Regardless of the number of degrees of freedom available for controlling the position of the end effector, the manipulator assemblies described herein may also facilitate additional degrees of freedom for actuating a tool (i.e., actuation degrees of freedom). For example, the manipulator assemblies may be configured to mount a tool having an electrocautery probe operable to, e.g., heat select tissue upon activation. For another example, the manipulator assemblies may be configured to mount a tool having a vacuum operable to, e.g., apply suction forces around select tissue upon activation. In such cases, these additional degrees of freedom are not kinematic, and therefore do not affect the position (i.e., location and orientation) of the end effector.

The term “state” of a joint or the like will often herein refer to the control variables associated with the joint. For example, the state of an angular joint can refer to the angle defined by that joint within its range of motion, and/or to the angular velocity of the joint. Similarly, the state of an axial or prismatic joint may refer to the joint's axial position, and/or to its axial velocity. While many of the controllers described herein comprise velocity controllers, they often also have some position control aspects. Alternative embodiments may rely primarily or entirely on position controllers, acceleration controllers, or the like. Many aspects of control systems that can be used in such devices are more fully described in U.S. Pat. No. 6,699,177, the full disclosure of which is incorporated herein by reference. Hence, so long as the movements described are based on the associated calculations, the calculations of movements of the joints and movements of an end effector described herein may be performed using a position control algorithm, a velocity control algorithm, a combination of both, and/or the like.

In many embodiments, the tool of an exemplary manipulator arm pivots about a pivot point adjacent a minimally invasive aperture. In some embodiments, the system may utilize a hardware remote center, such as the remote center kinematics described in U.S. Pat. No. 6,786,896, the entire contents of which are incorporated herein in its entirety. Such systems may utilize a double parallelogram linkage which constrains the movement of the linkages such that the shaft of the instrument supported by the manipulator pivots about a remote center point. Alternative mechanically constrained remote center linkage systems are known and/or may be developed in the future. In other embodiments, the system may utilize software to achieve a remote center, such as described in U.S. Pat. No. 8,004,229, the entire contents of which are incorporated herein by reference. In a system having a software remote center, the processor calculates movement of the joints so as to pivot an intermediate portion of the instrument shaft about a desired pivot point, as opposed to a mechanical constraint. By having the capability to compute software pivot points, different modes characterized by the compliance or stiffness of the system can be selectively implemented. More particularly, different system modes over a range of pivot points/centers (e.g., moveable pivot points, passive pivot points, fixed/rigid pivot point, soft pivot points) can be implemented as desired.

In many configurations, robotic surgical systems may include master controller(s) having a number of degrees of freedom fewer than, more than, or equal to the number of degrees of freedom which the remotely controlled robotic manipulator arms and/or tools have. In such cases, Jacobian based or other controllers used to control the robotic manipulator arms and/or tools typically provide complete mathematical solutions and satisfactory control. For example, fully controlling the position (i.e., location and orientation) of a rigid body can employ six independently controllable degrees of freedom of the rigid body, which includes three degrees of freedom for translations and three degrees of freedom for orientations. This lends itself nicely to a Jacobian based control algorithm in which a 6×N Jacobian matrix is used.

However, when a 6×N Jacobian controller is used to control robotic manipulator arms and/or tools having fewer than 6 degrees of freedom, problems can be introduced since the mathematical problem is overconstrained. For example, where the remote tool is a rigid endoscope extending through a minimally invasive aperture (so that the endoscope pivots at the aperture), two manipulator degrees of freedom may not be available (those often associated with a tool wrist adjacent the end effector, e.g., wrist pitch and yaw. Each of these two missing manipulator degrees of freedom affects both translations and orientations of the end effector. Accordingly, the endoscope only has four independently controllable degrees of freedom at its tip (i.e., end effector degrees of freedom), which can result in the aforementioned mathematical problems for a 6×N Jacobian approach. In practice, these mathematical problems often become tangible. When, for example, the endoscope tip is commanded to either pan or tilt, since it has a non-wristed tip, it can only do one thing, and that is to do a combination of both. In other words, the endoscope tip may not be independently controlled to pan or tilt; rather, it can only perform a fixed combination of these. This can potentially result in a sluggish, unresponsive feel to the surgeon which is undesirable.

Further problems often arise when tools having different degrees of freedom are used with the same robotic surgical manipulator. For example, a surgeon may wish to use jaws having three kinematic degrees of freedom, and then replace the jaws with a suction device having two kinematic degrees of freedom. Since the mathematical model for controlling the motion of the jaws is different than that for controlling the motion of the suction device, the robotic system applies two different models to avoid the aforementioned problems resulting from the same mathematical model being used. For example, where the manipulator provides three degrees of freedom in addition to the degrees of freedom of the tool, controllers for controlling the motion of the jaws and the suction device may include a 6×N Jacobian based controller and a 5×(N−1) Jacobian based controller, respectively. The use of multiple controllers results in an added layer of complexity that may increase cost and/or limit scalability for a large set of different tools, and a 5×(N−1) Jacobian is more complicated to use due to its reduced number of rows.

Yet further problems often arise when using estimates of the current joint positions of the manipulator assembly to control subsequent movements of the joints. Joint controllers may use the combination of desired joint positions and estimates of the current joint positions to determine the appropriate torque to apply to the joints so as to move the joints closer to the desired joint positions. In situations where the number of degrees of freedom of the kinematic model of a manipulator assembly are equal to the number of degrees of freedom of the manipulator assembly, but the position of a tool tip is measured in a greater number of degrees of freedom, using those measurements as inputs to the kinematic model to determine joint angles results in errors being imposed in the resulting joint angle calculations. These errors result in undesirable control of the manipulator assembly when those joint angle calculations are used to control motion of the manipulator assembly.

Although manipulator assemblies having a variety of degrees of freedom are disclosed herein, including assemblies having fewer than, the same number as, or more than the six degrees of freedom for fully controlling the position of an end effector, many embodiments of these assemblies lack at least one degree of freedom for fully controlling the position of the end effector. While the manipulator assemblies may lack one of these degrees of freedom, the input device controlling the manipulator assembly (e.g., a master control input device) may include the lacking degree of freedom. In accordance with embodiments of the present invention, in response to an input controlling the degree(s) of freedom missing at the manipulator assembly, the other degrees of freedom available at the manipulator assembly may provide motions so as to simulate control of the missing degree(s) of freedom. This may be done by using a kinematic model of the manipulator assembly that includes and performs calculations for the missing manipulator degree(s) of freedom. By performing such calculations, the remaining degrees of freedom of the manipulator assembly may be more effectively controlled to cause an end effector to appear to move along the requested degree(s) of freedom. Further, the use of such a kinematic model may advantageously reduce the complexity of facilitating the positioning and/or actuation of tools having different numbers of degrees of freedom.

Referring now to the drawings, in which like reference numerals represent like parts throughout the several views,FIG. 1Ais an overhead view illustration of a Minimally Invasive Robotic Surgical (MIRS) system10, in accordance with many embodiments, for use in performing a minimally invasive diagnostic or surgical procedure on a patient12who is lying down on an operating table14. The system can include a surgeon's console16for use by a surgeon18during the procedure. One or more assistants20may also participate in the procedure. The MIRS system10can further include a patient side cart22(surgical robot) and an electronics cart24. The patient side cart22can manipulate at least one removably coupled tool assembly26(hereinafter simply referred to as a “tool”) through a minimally invasive incision in the body of the patient12while the surgeon18views the surgical site through the console16. An image of the surgical site can be obtained by an imaging device28, such as a stereoscopic endoscope, which can be manipulated by the patient side cart22so as to orient the imaging device28. The electronics cart24can be used to process the images of the surgical site for subsequent display to the surgeon18through the surgeon's console16. The number of surgical tools26used at one time will generally depend on the diagnostic or surgical procedure and the space constraints within the operating room among other factors. If it is necessary to change one or more of the tools26being used during a procedure, an assistant20may remove the tool26from the patient side cart22, and replace it with another tool26from a tray30in the operating room.

MIRS system10in certain embodiments is a system for performing a minimally invasive diagnostic or surgical procedure on a patient including various components such as a surgeon's console16, an electronics cart24, and a patient side cart22. However, it will be appreciated by those of ordinary skill in the art that the system could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 1A. Thus, the depiction of the system10inFIG. 1Ashould be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 1Bdiagrammatically illustrates a robotic surgery system50(such as MIRS system10ofFIG. 1A). As discussed above, a surgeon's console52(such as surgeon's console16inFIG. 1A) can be used by a surgeon to control a patient side cart (surgical robot)54(such as patient side cart22inFIG. 1A) during a minimally invasive procedure. The patient side cart54can use an imaging device, such as a stereoscopic endoscope, to capture images of the procedure site and output the captured images to an electronics cart56(such as the electronics cart24inFIG. 1A). As discussed above, the electronics cart56can process the captured images in a variety of ways prior to any subsequent display. For example, the electronics cart56can overlay the captured images with a virtual control interface prior to displaying the combined images to the surgeon via the surgeon's console52. The patient side cart54can output the captured images for processing outside the electronics cart56. For example, the patient side cart54can output the captured images to a processor58, which can be used to process the captured images. The images can also be processed by a combination of the electronics cart56and the processor58, which can be coupled together so as to process the captured images jointly, sequentially, and/or combinations thereof. One or more separate displays60can also be coupled with the processor58and/or the electronics cart56for local and/or remote display of images, such as images of the procedure site, or other related images.

MIRS system50in certain embodiments is a system for performing a minimally invasive diagnostic or surgical procedure on a patient including various components such as a surgeon's console52, an electronics cart56, and a patient side cart54. However, it will be appreciated by those of ordinary skill in the art that the system could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 1B. Thus, the depiction of the system50inFIG. 1Bshould be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 2is a perspective view of the surgeon's console16. The surgeon's console16includes a left eye display32and a right eye display34for presenting the surgeon18with a coordinated stereo view of the surgical site that enables depth perception. The console16further includes one or more input control devices36, which in turn cause the patient side cart22(shown inFIG. 1A) to manipulate one or more tools. The input control devices36can provide the same degrees of freedom, or more degrees of freedom, as their associated tools26(shown inFIG. 1A) so as to provide the surgeon with telepresence, or the perception that the input control devices36are integral with the tools26so that the surgeon has a strong sense of directly controlling the tools26. To this end, position, force, and tactile feedback sensors (not shown) may be employed to transmit position, force, and tactile sensations from the tools26back to the surgeon's hands through the input control devices36.

The surgeon's console16is usually located in the same room as the patient so that the surgeon may directly monitor the procedure, be physically present if necessary, and speak to an assistant directly rather than over the telephone or other communication medium. However, the surgeon can be located in a different room, a completely different building, or other remote location from the Patient allowing for remote surgical procedures.

Surgeon's console16in certain embodiments is a device for presenting the surgeon with information concerning the surgical site and receiving input information from the surgeon, and includes various components such as eyes displays and input control devices. However, it will be appreciated by those of ordinary skill in the art that the surgeon's console could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 2. Thus, the depiction of the surgeon's console16inFIG. 2should be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 3is a perspective view of the electronics cart24. The electronics cart24can be coupled with the imaging device28and 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 cart24can process the captured images so as 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 so as to compensate for imaging errors of the image capture device, such as optical aberrations.

The electronics cart24in certain embodiments is a device for presenting information concerning a surgery to a surgical team and includes various components displays, processors, storage elements, etc. However, it will be appreciated by those of ordinary skill in the art that the electronics cart could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 3. Thus, the depiction of the electronics cart24inFIG. 3should be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 4shows a patient side cart22having a plurality of manipulator arms, each supporting a surgical instrument or tool26at a distal end of the manipulator arm. The patient side cart22shown includes four manipulator arms100which can be used to support either a surgical tool26or an imaging device28, such as a stereoscopic endoscope used for the capture of images of the site of the procedure. Manipulation is provided by the robotic manipulator arms100having a number of robotic joints, where each joint provides a manipulator degree of freedom. The angle of each joint may be controlled by an actuator such as a motor or motor assembly, and in some embodiments the angle of each joint may be measured using one or more sensors (e.g., encoders, or potentiometers, or the like) disposed on or proximate to each joint. The imaging device28and the surgical tools26can be positioned and manipulated through incisions in the patient so that a kinematic remote center is maintained at the incision so as to minimize the size of the incision. Images of the surgical site can include images of the distal ends of the surgical instruments or tools26when they are positioned within the field-of-view of the imaging device28.

Regarding surgical tool26, a variety of alternative robotic surgical tools or instruments of different types and differing end effectors may be used, with the instruments of at least some of the manipulators being removed and replaced during a surgical procedure. Several of these end effectors, including DeBakey Forceps, microforceps, Potts scissors, and clip applier include first and second end effector elements which pivot relative to each other so as to define a pair of end effector jaws. Other end effectors, including scalpel and electrocautery probe have a single end effector element. For instruments having end effector jaws, the jaws will often be actuated by squeezing the grip members of handle. Single end effector instruments may also be actuated by gripping of the grip members, for example, so as to energize an electrocautery probe.

The elongate shaft of instrument26allows the end effectors and the distal end of the shaft to be inserted distally into a surgical worksite through a minimally invasive aperture, often through an abdominal wall or the like. The surgical worksite may be insufflated, and movement of the end effectors within the patient will often be affected, at least in part, by pivoting of the instrument26about the location at which the shaft passes through the minimally invasive aperture. In other words, manipulators100will move the proximal housing of the instrument outside the patient so that shaft extends through a minimally invasive aperture location so as to help provide a desired movement of end effector. Hence, manipulators100will often undergo significant movement outside the patient12during a surgical procedure.

The patient side cart22in certain embodiments is a device for providing surgical tools for assisting in a surgical procedure on a patient, and may include various components such as manipulator arms100and tools26. However, it will be appreciated by those of ordinary skill in the art that the patient side cart could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 4. Thus, the depiction of the patient side cart22inFIG. 4should be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

An exemplary manipulator arm in accordance with some embodiments of the present invention can be understood with reference toFIG. 5. As described above, a manipulator arm generally supports a distal instrument or surgical tool and affects movements of the instrument relative to a base. As a number of different instruments having differing end effectors may be sequentially mounted on each manipulator during a surgical procedure (typically with the help of a surgical assistant), a distal instrument holder will preferably allow rapid removal and replacement of the mounted instrument or tool. As can be understood with reference toFIG. 4, manipulators are proximally mounted to a base of the patient side cart. Typically, the manipulator arm includes a plurality of linkages and associated joints extending between the base and the distal instrument holder. In one aspect, an exemplary manipulator includes a plurality of joints having either redundant or non-redundant degrees of freedom, but is lacking at least one degree of freedom necessary to fully prescribe the position (i.e., location and orientation) of the end effector.

In many embodiments, such as that shown inFIG. 5, an exemplary manipulator arm includes a proximal revolute joint J1that rotates about a first joint axis so as to revolve the manipulator arm distal of the joint about the joint axis. In some embodiments, revolute joint J1is mounted directly to the base, while in other embodiments, joint J1may be mounted to one or more movable linkages or joints. The joints of the manipulator, in combination, may have redundant degrees of freedom such that the joints of the manipulator arm can be driven into a range of differing configurations for a given end effector position. For example, the manipulator arm ofFIG. 5may be maneuvered into differing configurations while the distal instrument or tool511supported within the instrument holder510maintains a particular state, which may include a given position or velocity of the end effector. In some embodiments, the joints of the manipulator are not operable to independently control at least one of the six end effector degrees of freedom that fully define the position of the tool511. For example, the manipulator may not be operable to cause the tool511to independently roll, pitch, yaw, and/or translate in one or more directions.

Describing the individual links of manipulator arm500ofFIG. 5along with the axes of rotation of the joints connecting the links as illustrated inFIG. 5, a first link504extends distally from a pivotal joint J2which pivots about its joint axis and is coupled to revolute joint J1which rotates about its joint axis. Many of the remainder of the joints can be identified by their associated rotational axes, as shown inFIG. 5. For example, a distal end of first link504is coupled to a proximal end of a second link506at a pivotal joint J3that pivots about its pivotal axis, and a proximal end of a third link508is coupled to the distal end of the second link506at a pivotal joint J4that pivots about its axis, as shown. The distal end of the third link508is coupled to instrument holder510at pivotal joint J5. Typically, the pivotal axes of each of joints J2, J3, J4, and J5are substantially parallel and the linkages appear “stacked” when positioned next to one another, so as to provide a reduced width of the manipulator arm and improve patient clearance during maneuvering of the manipulator assembly. In many embodiments, the instrument holder510also includes additional joints, such as a prismatic joint J6that facilitates axial movement of the instrument511through the minimally invasive aperture and facilitates attachment of the instrument holder510to a cannula through which the instrument511is slidably inserted. In some embodiments, even when combining the degrees of freedom of the instrument holder510with the rest of those of manipulator arm500, the resulting degrees of freedom are still insufficient to provide at least one of the six degrees of freedom necessary to fully define the position of the tool511.

The instrument511may include additional degrees of freedom distal of instrument holder510. Actuation of the degrees of freedom of the instrument will often be driven by motors of the manipulator, and alternative embodiments may separate the instrument from the supporting manipulator structure at a quickly detachable instrument holder/instrument interface so that one or more joints shown here as being on the instrument are instead on the interface, or vice versa. In some embodiments, instrument511includes a rotational joint J7(not shown) near or proximal of the insertion point of the tool tip or the pivot point PP, which generally is disposed at the site of a minimally invasive aperture. A distal wrist of the instrument allows pivotal motion of an end effector of surgical tool511about instrument joints axes of one or more joints at the instrument wrist. An angle between end effector jaw elements may be controlled independently of the end effector location and orientation. Notwithstanding these additional kinematic degrees of freedom provided by the surgical tool511, which may be considered to be part of the manipulator degrees of freedom, in some embodiments, even when combining the kinematic degrees of freedom of the surgical tool511with those of manipulator arm500(including, e.g., those of instrument holder510), the resulting kinematic degrees of freedom are still insufficient to fully control the position of the tip of tool511.

The manipulator arm500in certain embodiments is a mechanical body for holding and controlling a tool, and may include a number of links and joints. However, it will be appreciated by those of ordinary skill in the art that the manipulator arm could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 5. Thus, the depiction of the manipulator arm500inFIG. 5should be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 6Ashows a surgical tool600that includes a proximal chassis602, an instrument shaft604, and a distal end effector606having a jaw608that can be articulated to grip a patient tissue. The proximal chassis includes an input coupler that is configured to interface with and be driven by an output coupler of the patient side cart22(FIG. 1A). The input coupler is drivingly coupled with an input link of a spring assembly610. The spring assembly610is mounted to a frame612of the proximal chassis602and includes an output link that is drivingly coupled with a drive shaft that is disposed within the instrument shaft604. The drive shaft is drivingly coupled with the jaw608.

In accordance with some embodiments and as shown inFIG. 6A, the surgical tool600may not include any degrees of freedom for altering a position of the end effector606. In other embodiments, the surgical tool600may include one or more joints for adding degrees of freedom for altering the position of the end effector606. For example, the instrument shaft604may include joints for changing a pitch and/or yaw of the end effector606. Further, in some embodiments and as shown inFIG. 6A, the surgical tool600may include one or more degrees of freedom for actuating the end effector606. For example, the spring assembly610may be operable to actuate the jaw608. Additional characteristics of surgical tool600, as well as other surgical tools, are described in commonly-owned U.S. application Ser. No. 13/297,158, filed Nov. 15, 2011, entitled “Method for Passively Decoupling Torque Applied By a Remote Actuator Into an Independently Rotating Member,” the disclosure of which is incorporated herein by reference in its entirety.

FIG. 6Billustrates a wristed endoscope620that may, in some embodiments, be used in robotic minimally invasive surgery. The endoscope620includes an elongate shaft622and a flexible wrist624located at the working end of the shaft622. A housing626allows the surgical instrument620to releasably couple to a manipulator located at the opposite end of the shaft624. An endoscopic camera lens is implemented at the distal end of the flexible wrist624. A lumen (not shown) runs along the length of the shaft622which connects the distal end of the flexible wrist624to the housing626. In a “fiber scope” embodiment, imaging sensor(s) of the endoscope620, such as charge coupled devices (CCDs), may be mounted inside the housing626with connected optical fibers running inside the lumen along the length of the shaft622and ending at substantially the distal end of the flexible wrist624. In an alternate “chip-on-a-stick” embodiment, the imaging sensor(s) of the endoscope620may be mounted at the distal end of the flexible wrist624. The imaging sensor(s) may be two-dimensional or three-dimensional.

In some embodiments, the flexible wrist624may have at least one degree of freedom to allow the endoscope620to articulate and maneuver easily around internal body tissues, organs, etc. to reach a desired destination (e.g., epicardial or myocardial tissue). The housing626may house a drive mechanism for articulating the distal portion of the flexible wrist624. The drive mechanism may be cable-drive, gear-drive, belt drive, or another type of drive mechanism suitable to drive the flexible wrist624along its degree(s) of freedom. For example, in one embodiment, the flexible wrist624may have two translation degrees of freedom and the shaft622may be operable to rotate around an axis along the length of the shaft622. In some medical procedures, the articulate endoscope620maneuvers and articulates around internal organs, tissues, etc. to acquire visual images of hard-to-see and/or hard-to-reach places. Additional characteristics of the endoscope620, as well as other surgical tools, are described in commonly-owned U.S. application Ser. No. 11/319,011, filed Dec. 27, 2005, entitled “Articulate and Swapable Endoscope for a Surgical Robot,” the disclosure of which is incorporated herein by reference in its entirety.

FIG. 6Cis a perspective view of the distal end of an overtube with suction ports. The overtube630defines an instrument lumen632which extends through the overtube630to permit passage of an instrument. The overtube630further comprises one or more suction passages634which are coupled to a vacuum source. The overtube630may, in various embodiments, be formed out of any of a variety of materials suitable for surgical use and may be provided with any of variety of stiffnesses. For example, the overtube630may comprise a substantially rigid material, may comprise a flexible material, or may comprise a combination of one or more substantially rigid portions and one or more flexible portions to provide a bendable structure. The cross-sectional shape of the overtube630may also vary. In the illustrated embodiment, the overtube630has a substantially circular cross-sectional shape and is made out of polyurethane. In other embodiments, other cross-sectional shapes may be used, such as, e.g., oval, rectangular, triangular, etc., depending on the application.

In the illustrated embodiment, the suction passages634comprise a plurality of vacuum lumens within the wall of the overtube630, with each vacuum lumen being coupled to the vacuum source (not shown). The vacuum source may be operated to create a vacuum pressure in each suction passage634, thereby creating a suction force onto a tissue surface which the suction passages634are in contact with. As a result of this suction force, the overtube630will be attached to the tissue surface. If the vacuum pressure is discontinued, the tissue surface will be released and the overtube630will no longer be attached to the tissue. Accordingly, by controllably providing a suction force via the suction passages634, the overtube630can be releasably attached to patient's tissue surface. A surgical instrument, such as an irrigation tool, cutting tool, etc., may then be inserted through the instrument lumen200to treat tissue disposed within the instrument lumen632.

In accordance with some embodiments, the overtube630may be made of substantially rigid material and not include any degrees of freedom for altering a position of the overtube630. In other embodiments, the overtube630may include one or more joints for adding degrees of freedom for altering the position of the distal end of the overtube630. For example, the overtube630may include joints for changing a pitch and/or yaw of the distal end of the overtube630. Further, in some embodiments, the overtube630may include one or more degrees of freedom for actuating functionality of the overtube630. For example, a vacuum source (not shown) may be operable to create or remove a vacuum pressure in one or more suction passages634. Additional characteristics of the overtube630, as well as other surgical tools, are described in commonly-owned U.S. application Ser. No. 11/618,374, filed Dec. 29, 2006, entitled “Vacuum Stabilized Overtube for Endoscopic Surgery,” the disclosure of which is incorporated herein by reference in its entirety.

FIG. 6Dillustrates a non-wristed endoscope640that may, in some embodiments, be used in robotic minimally invasive surgery. The non-wristed endoscope640is similar to the wristed endoscope620depicted in and discussed with reference toFIG. 6B, and thus similarly includes a housing646and a shaft622. The difference is that the non-wristed endoscope640does not include a flexible wrist. The non-wristed endoscope has a reduced number of degrees of freedom compared to the wristed endoscope, and in this particular example, non-wristed endoscope640does not have a wrist pitch or wrist yaw.

The surgical tool600, endoscope620, and overtube30are various tools that include a variety of components. However, it will be appreciated by those of ordinary skill in the art that these tools could operate equally well by having fewer or a greater number of components than are illustrated inFIGS. 6A to 6C. Further, it would will also be appreciated that other tools may also or alternatively be used, such as gripping devices, electrosurgical paddles, vacuums, irrigators, staplers, scissors, knifes, etc. Thus, the depiction of surgical tools inFIGS. 6A to 6Cshould be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 7Ais a perspective view of a master control input device700that may be part of a surgeon's console16(FIG. 1A) in accordance with an embodiment. The master control700includes a gimbal or wrist720that is operatively coupled to an articulated arm740.

Master control input device700has a number of degrees of freedom and is operable to control a manipulator assembly (e.g., manipulator arm500ofFIG. 5). The degrees of freedom of input device700includes kinematic degrees of freedom defined by joints of input device700, used to control the kinematics of manipulator arm500, and may also include actuation degrees of freedom used to actuate a tool (e.g., instrument511) connected to manipulator arm500. Input device700, like a tool of manipulator arm500, may also be considered to have an end effector (or, more generally, a control frame) associated therewith, which itself has a number of kinematic degrees of freedom.

In some embodiments, input device700may have a sufficient number of degrees of freedom to fully control the position of an end effector. For example, the input device700may have six degrees of freedom that may independently control the three translation and three orientation degrees of freedom of an end effector of the instrument511. In some cases, even though the input device700has such a sufficient number of degrees of freedom, the manipulator assembly (e.g., manipulator arm500) has a number of degrees of freedom that is insufficient to independently control the three translation and three orientation degrees of freedom of the end effector. For example, the manipulator arm500may have only five degrees of freedom.

In some embodiments, the input device700may have additional degrees of freedom, which may be degrees of freedom operable to control the position of the end effector (e.g., a redundant degree of freedom), and/or may be degrees of freedom operable to actuate the instrument26(e.g., turning on or off suction or irrigation, actuating a clamp, engaging a staple with tissue, etc.). An input device having additional degrees of freedom is described in commonly-owned U.S. application Ser. No. 10/121,283, filed Apr. 11, 2002, entitled “Master Having Redundant Degrees of Freedom,” the disclosure of which is incorporated herein by reference in its entirety. Further, in at least one embodiment, the instrument511, either alone or in combination with a manipulator arm500, may have additional kinematic degrees of freedom that add to the degrees of freedom of the manipulator arm500. For example, the instrument511may have joints for controlling the position of the end effector. In some cases, even when combining the kinematic degrees of freedom of the manipulator arm500with the kinematic degrees of freedom of the instrument, the position of the end effector may not be fully controlled. This may be, e.g., due to the joints of the instrument511merely adding kinematic degrees of freedom that are redundant to those already provided by the manipulator arm500. In some embodiments, the instrument511may have additional actuation degrees of freedom for actuating the instrument511(e.g., turning on or off suction or irrigation, actuating a clamp, engaging a staple with tissue, etc.).

To facilitate control of the instrument511, the master control input device700may include one or more actuators or motors and, in some embodiments, sensors for each of a plurality of joints of the master control input device700. The motors and sensors of the input device700may be operatively linked to the motors and sensors associated with the manipulator arms (e.g., arm500ofFIG. 5) and the surgical instruments mounted thereon (e.g., instrument511ofFIG. 5) via a control system disposed in, e.g., the surgeon's console16, the electronics cart24, and/or the patient cart22, and/or any other element of MIRS system10(FIG. 1). The control system may include one or more processors for effecting control between the master control device input and responsive robotic arm and surgical instrument output and for effecting control between robotic arm and surgical instrument input and responsive master control output in the case of, e.g., force feedback.

FIG. 7Bis a perspective view of a gimbal or wrist720according to an embodiment. According to this embodiment, gimbal or wrist720allows rotation of an actuatable handle722about three axes, axis 1, axis 2, and axis 3. More specifically, the handle722is coupled to a first elbow-shaped link724by a first pivotal joint726. The first link724is coupled to a second elbow-shaped link728by a second pivotal joint730. The second link728is pivotally coupled to a third elbow-shaped link732by a third pivotal joint734. The gimbal or wrist720may be mounted on an articulated arm740(as shown inFIG. 7A) at axis 4 such that the gimbal or wrist720can displace angularly about axis 4. By way of such links and joints, the gimbal or wrist720may provide a number of kinematic degrees of freedom for the control input device700and be operable to control one or more of the end effector degrees of freedom.

In some embodiments, the handle722may include a pair of grip members723for actuating a tool or end effector. For example, by opening or closing the grip members723, the jaw608of the end effector606(FIG. 6) may similarly be opened or closed. In other embodiments, one or more input elements of the handle722and/or of other elements of the surgeon's console16may be operable to actuate one or more degrees of freedom of the instrument511other than degrees of freedom for controlling the position of the instrument26. For example, the surgeon's console16may include a foot pedal coupled to the control system for activating and deactivating a vacuum pressure.

In some embodiments, the joints of the gimbal or wrist720may be operatively connected to actuators, e.g., electric motors, or the like, to provide for, e.g., force feedback, gravity compensation, and/or the like. Furthermore, sensors such as encoders, potentiometers, and the like, may be positioned on or proximate to each joint of the gimbal or wrist720, so as to enable joint positions of the gimbal or wrist720to be determined by the control system.

FIG. 7Cis a perspective view of an articulated arm740according to an embodiment. According to this embodiment, the articulated arm740allows rotation of a gimbal or wrist720(FIG. 7B) about three axes, axis A, axis B, and axis C. More specifically, the gimbal or wrist720may be mounted on the arm740at axis 4 as previously described with reference toFIG. 7B. The gimbal or wrist720is coupled to a first link742which is pivotally coupled to a second link744by a first pivotal joint746. The second link744is pivotally coupled to a third link748by a second pivotal joint750. The third link748may be pivotally coupled to the surgeon's console16(FIG. 1) by a third pivotal joint752. By way of such links and joints, the articulated arm740may provide a number of kinematic degrees of freedom for the control input device700and be operable to control one or more of the kinematic degrees of freedom of a manipulator assembly to thereby control the position of an instrument (e.g., instrument511ofFIG. 5).

In some embodiments, the joints of the articulated arm740may be operatively connected to actuators, e.g., electric motors, or the like, to provide for, e.g., force feedback, gravity compensation, and/or the like. Furthermore, sensors such as encoders, potentiometers, and the like, may be positioned on or proximate to each joint of the articulated arm740, so as to enable joint positions of the articulated arm740to be determined by the control system.

Input device700in certain embodiments is a device for receiving inputs from a surgeon or other operator and includes various components such as a gimbal or wrist720and an articulated arm740. However, it will be appreciated by those of ordinary skill in the art that the input device could operate equally well by having fewer or a greater number of components than are illustrated inFIGS. 7A to 7C. Thus, the depiction of the input device700inFIGS. 7A to 7Cshould be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 8is a block diagram showing a simplified system800for controlling a mechanical body having fewer degrees of freedom than those mathematically modeled. The system800includes an information source810, a kinematic processor820having a kinematic model822, one or more actuators830, and a mechanical body840.

The information source810may be any suitable source of control information812for controlling a position of the mechanical body. In one embodiment, the information source810is an input device such as the surgeons console16(FIG. 1), the input control devices36(FIG. 2), and/or the master control input device700(FIGS. 7A to 7C). In such embodiments, the control information812may be a desired position of a mechanical body having N degrees of freedom. In one embodiment, the N degrees of freedom are those necessary to fully define the position of the mechanical body, i.e., three independently controllable translations and three independently controllable rotations. Accordingly, the output from the information source810may include parameters for fully controlling the position of the mechanical body. In one embodiment, the N degrees of freedom are insufficient to fully define the position of the mechanical body. For example, the N degrees are freedom are insufficient to independently control all three translations and three rotations of the mechanical body. Accordingly, the output from the information source810may include parameters insufficient to fully control the position of the mechanical body. In yet another embodiment, the N degrees of freedom may include one or more degrees of freedom that do not define the position of the mechanical body (i.e., non-kinematic degrees of freedom). For example, the N degrees of freedom may include one or more degrees of freedom for actuating an instrument such as actuating a vacuum pressure. Accordingly, the output from the information source810may include parameters for controlling non-kinematic characteristics of the mechanical body. These may not be limited to suction via a vacuum pressure, but may also or alternatively include irrigating, energizing (e.g., cauterizing), cutting (using, e.g., a single blade or multiple blades like scissors), and grasping (using, e.g., pincers, fingers, or the like).

In some embodiments, when the information source810is an input device, the input device itself also has N degrees of freedom, such that, at least in some cases, each degree of freedom of the input device may correspond to a degree of freedom of the mechanical body. For example, a roll of the input device may correspond to a desired roll of the mechanical body, or a pitch of the input device may correspond to a desired pitch of the mechanical body. In other embodiments, the input device may have a number of degrees of freedom greater than or fewer than the mechanical body. For example, the input device may have one or more redundant degrees of freedom, whereas the mechanical body may have no redundant degrees of freedom. For another example, the mechanical body may have one or more redundant degrees of freedom, whereas the input device may have no redundant degrees of freedom.

Although the input device provides an output indicating a desired position of a mechanical body having N degrees of freedom, the mechanical body840controlled by the input device lacks at least one of the necessary degrees of freedom for fully defining the position of the mechanical body. For example, the mechanical body840may lack a roll, yaw, and/or pitch degree of freedom, and/or may lack an up/down, left/right, and/or forward/backward translation degree of freedom. In the case where N represents the number of degrees of freedom for controlling a position of a mechanical body, and M represents the number of degrees of freedom regarding position that the mechanical body lacks, then in one embodiment the mechanical body may have N−M degrees of freedom. For example, N may be equal to six, corresponding to all three translations and all three rotations of a mechanical body, whereas M may represent one, corresponding to the roll of the mechanical body. However, in other embodiments, the mechanical body may have Nor even greater than N degrees of freedom, such as where the mechanical body includes redundant degrees of freedom, but still lacks at least one degree of freedom necessary to fully define the position of the mechanical body.

In other embodiments, the information source810is not an input device like a surgeon's console, but rather is a tool position measuring device. In this case, the kinematic block820is not a controller, but is a joint position estimator. For example, the tool position measuring device may include an optical fiber that extends the length of tool assembly26to the free end of the tool assembly26, an electromagnetic sensor arranged proximate the joints of the manipulator assembly, or other sensor or imaging device operable to measure a position of the joints of the manipulator assembly. In many embodiments, the tool position measuring device is small and light enough so as not to interfere with motion of the tool. In an embodiment where the tool position measuring device includes an optical fiber, the properties (e.g., the refractive index) of the optical fiber may be altered as a result of changes in joint positions. Some examples of fiber optic sensors are described in U.S. Pat. App. Pub. No. US2007/0156019 A1 (filed Jul. 20, 2006), entitled “Robotic Surgery System Including Position Sensors Using Fiber Bragg Gratings” by Larkin et al., and U.S. patent application Ser. No. 12/164,829 (filed Jun. 30, 2008) entitled “Fiber optic shape sensor” by Giuseppe M. Prisco, both of which are incorporated herein by reference in their entirety for all purposes. The tool position measuring device may then be operable to determine a position of the tip of the tool (e.g., the free end of tool assembly26) based on the altered properties of the optical fiber. The tool position measuring device may further be operable to measure a position of the tool in a number of degrees of freedom. For example, the tool position measuring device may measure one, two, or three translational positions of the tool (e.g., x, y, z positions), and/or one, two or three orientational positions of the tool (e.g., pitch, yaw, roll). In at least one embodiment, the tool position measuring device may be inoperable to measure one or more degrees of freedom positions of the tool. For example, when the tool position measuring device includes an optical fiber and deduces a tip position based on changes to the properties of the optical fiber, the tool position measuring device may have difficulty determining a roll movement of the tool. In embodiments where the information source810is a tool position measuring device, control information812may be measurement information indicating a measured position of the degrees of freedom of the tool tip.

In some embodiments, the tool position measuring device may be operable to measure the position of a number of degrees of freedom of the tool less than, equal to, or greater than a number of degrees of freedom of the manipulator assembly. In many embodiments, as already described for information sources being input devices, the mechanical body may have N degrees of freedom that are insufficient to fully define the position of the mechanical body, may include non-kinematic degrees of freedom, may include redundant degrees of freedom, etc.

The output from the information source810, regardless of whether the information source810is an input device or a tool position measuring device, is applied to a kinematic model822of an N degree of freedom mechanical body in the kinematic processor820. The kinematic processor820may be provided in any suitable component of MIRS system10(FIG. 1), such as the surgeon's console16, electronics cart24, and/or patient side cart22, tool assembly26, manipulator assembly, and/or the control system discussed with reference toFIG. 7A.

In embodiments where the information source810is an input device, the kinematic model822may be a model of a mechanical body having N degrees of freedom that correspond to the N degrees of freedom for which a desired control is output from the input device. For example, the input device may output parameters for fully controlling the position of the mechanical body, such as parameters for controlling three translations and three rotations of the mechanical body. The kinematic model822may then be a kinematic model of a mechanical body having three translations and three rotations. In some embodiments, one or more degrees of freedom that do not define the position of the mechanical body may be modeled or otherwise controlled separate from the kinematic model822. Regardless, in most embodiments, the kinematic model822includes a mathematical representation of the one or more degrees of freedom lacking in the mechanical body840. For example, the mechanical body840may lack a degree of freedom for controlling a roll of the mechanical body840. However, the kinematic model822may be of a mechanical body having a degree of freedom for controlling the roll of the mechanical body, and the input device810may output information indicating a desired control of the roll of the mechanical body.

In embodiments where the information source810is a tool position measuring device, the kinematic model822may be a model of a mechanical body for which joint estimates (i.e., estimates of the position of joints corresponding to the degrees of freedom of the mechanical body840) are to be generated. For example, if a joint estimation technique is used in which the tool position measurement device can only provide N degrees of freedom measurement, then the kinematic model822may have at least N degrees of freedom, the mechanical body may have (N−M) degrees of freedom, etc. However, in other embodiments, the mechanical body may have greater than N degrees of freedom, the manipulator assembly may be logically separated into multiple parts in which each part has no more than N joints or kinematic degrees of freedom while the tool measurement tool device is used to measure the position and orientation at the end of each part.

As a result of applying the control information812from the information source810to the kinematic processor820, one or more individual control outputs824may be generated by the kinematic processor820and communicated to one or more actuators830operable to affect control of one or more of the degrees of freedom of the mechanical body840. The number of individual control outputs824generated and communicated to the actuators830is fewer than the total number of individual control outputs824that may be generated by the kinematic processor820. That is, the individual control outputs824communicated to the actuators830do not include information for controlling the degree(s) of freedom that the mechanical body840lacks. For example, the kinematic model822may model a mechanical body having degrees of freedom for fully defining the position of the mechanical body, and may calculate outputs for controlling all of those degrees of freedom. However, only a subset of those calculated outputs are used, as the mechanical body actually controlled (i.e., mechanical body840) does not have all of the degrees of freedom modeled by the kinematic model822. Accordingly, the individual control outputs824communicated to the actuators830are only a subset of the possible instructions that may be generated using the kinematic model822.

In embodiments where the information source810is an input device, the individual control outputs824may include information indicating the desired position of a degree of freedom of the mechanical body840. For example, an individual control output824may indicate the desired position (e.g., angle) of a joint associated with one of the degrees of freedom of the mechanical body840.

In embodiments where the information source810is a tool position measuring device, the individual control outputs824may include information indicating the actual position of a degree of freedom of the mechanical body840. For example, an individual control output824may indicate the actual position (e.g., angle) of a joint associated with one of the degrees of freedom of the mechanical body840.

The individual control outputs824are received by one or more actuators830for controlling at least some of the degrees of freedom of a mechanical body840. For example, the actuators830may be electric motors or the like operable to actuate joints of the mechanical body840, as previously discussed with reference to, e.g.,FIG. 5. In accordance with one embodiment, each actuator is operable to control a corresponding degree of freedom of the mechanical body840. However, in other embodiments, one actuator may be operable to control more than one or fewer than one degree of freedom of the mechanical body840.

The mechanical body840may be any suitable mechanical body having at least one degree of freedom. For example, the mechanical body may be a robotic manipulator arm (e.g., manipulator arm100described with reference toFIG. 4or manipulator arm500described with reference toFIG. 5) and/or surgical instrument (e.g., instrument26described with reference toFIG. 1Aor instrument511described with reference toFIG. 5). In some embodiments, the mechanical body may include the kinematic aspects of both a manipulator arm and surgical instrument.

As previously described, various embodiments incorporate information source810being an input device such that kinematic processor820outputs desired positions of the joints of body840, whereas other embodiments incorporate information source810being a tool position measuring device such that kinematic processor820outputs actual positions of the joints of body840. In yet other embodiments, a system may include both an input device for providing desired positions to a kinematic model and controller (i.e., a type of kinematic processor) unique to the input device, and a tool position measuring device for providing tool tip position information to a kinematic model and an estimator (i.e., a type of kinematic processor) unique to the tool position measuring device. In such a case, the kinematic model used by the tool tip position measuring device may be different than the kinematic model used by the input device. Further, the outputs of each kinematic model, i.e., the desired position and actual position of the joints of the manipulator assembly may be used together to calculate the actual amount of torque to be applied to each joint motor. In embodiments where a tool position measuring device is not provided, the system may acquire estimated joint positions and combine those with the desired positions output when using the input device to generate torque amounts. Some of these further embodiments are described with reference toFIG. 9.

System800in certain embodiments is a simplified system for controlling a mechanical body and includes various components such as an input device810, kinematic processor820, actuator(s)830, and mechanical body840. However, it will be appreciated by those of ordinary skill in the art that the system could operate equally well by having fewer or a greater number of components than are illustrated inFIG. 8. Thus, the depiction of the system800inFIG. 8should be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 9is a block diagram of an actuator830according an embodiment. The actuator830includes a joint controller832and a motor834, where the joint controller832is operable to generator a torque command836for controlling motor834. The motor834may be coupled to one or more joints of a manipulator assembly for controlling the degrees of freedom of the manipulator assembly. In this embodiment, the actuator830is operable to control degree of freedom (X).

To generate a torque command836, the joint controller834receives the desired position of the degree of freedom (X)824A. The desired position may be received from an input device such as a surgeon's console. For example, the desired position824A may be generated by the kinematic processor820(FIG. 8) when the information source810is an input device. Accordingly, the desired position824A may be generated by applying control information communicated from the input device to the kinematic model822, and using only one of a subset of the individual control outputs824as the desired position824A.

To generate the torque command836, the joint controller834also receives the actual position of the degree of freedom (X)824B. The actual position may be generated using one or more of a number of techniques. In one embodiment, the actual position may be determined based on encoders used for each joint motor. In other embodiments, the actual position may be calculated from the position (e.g., location and/or orientation) of the end of the manipulator assembly (e.g., a tool tip) and applying inverse kinematics. A sensor device for sensing the position of the end of the manipulator assembly may include an optical fiber disposed along the length of the manipulator assembly with one end fixed at the tool tip such that changes in joint position cause changes to properties (e.g., refractive index) of the optical fiber. In another embodiment, the sensor device may include one or more electromagnetic sensors attached to the end point of the manipulator assembly such that any changes in the tip position could be measured from the electromagnetic field generator. For example, with reference toFIG. 8, the information source810may be a sensing device operable to determine the tool tip position, and by applying the tool tip position measurement to the kinematic model822, one of a subset of the individual control output824may be used as the actual position824B.

Upon receiving both the desired position and the actual position of DOF(X), the joint controller832may determine the appropriate amount of motor torque that will cause the degree of freedom to move from its actual (i.e., current) position to the desired position. The joint controller832then sends the torque command836indicating this amount of torque to the motor834.

FIG. 10Ais a block diagram showing a simplified system1000for controlling a manipulator assembly using an input device in accordance with a first embodiment. System1000includes an input device1010, a controller1020, and a manipulator assembly1030. The input device1010may be similar to the information source810discussed with reference toFIG. 8, controller1020may be similar to the kinematic processor820discussed with reference toFIG. 8, and the manipulator assembly1030may be similar to the actuators and mechanical body840discussed with reference toFIG. 8. In one embodiment, the manipulator assembly1030includes a manipulator (e.g., manipulator500) and/or a tool (e.g., tool511). Manipulator assembly1030may have one or more manipulator kinematic degrees of freedom and, in some embodiments, may also or alternatively have one or more actuation degrees of freedom. Further, manipulator assembly1030may be operable to control the position of one or more end effectors (or, more generally, control frames). For example, an end effector could be defined at a tip of a tool that is part of manipulator assembly1030, part-way up a shaft of such a tool, etc. The end effector also has a number of degrees of freedom which may be the same as or different than the manipulator degrees of freedom.

In accordance with the embodiment depicted inFIG. 10A, the input device1010and controller1020are operable to control a greater number of kinematic manipulator degrees of freedom (i.e., degrees of freedom of manipulator assembly1030) than the manipulator assembly1030actually has. For example, the input device1010may have six kinematic degrees of freedom1012including three independently controllable rotation degrees of freedom and three independently controllable translation degrees of freedom. The input device1010outputs parameters or other information corresponding to the position of the input device1010or otherwise indicating a desired position of an end effector associated with manipulator assembly1030.

The output from the input device1010are received and processed by the controller1020to provide instructions for controlling the manipulator assembly1030(e.g., instructions for controlling motors associated with joints of manipulator assembly1030). In this embodiment, the controller1020includes a kinematic model1022of a manipulator assembly having six kinematic degrees of freedom for controlling three independently controllable rotation and three independently controllable translation degrees of freedom of the end effector.

A subset of the results from applying the output from the input device1010to the kinematic model1022are then used to control the manipulator assembly1030. For example, the subset of the results may be communicated to one or more actuators associated with joints of the manipulator assembly1030. The manipulator assembly1030in this embodiment has four kinematic degrees of freedom. The manipulator assembly1030is thus lacking two kinematic degrees of freedom. For example, the manipulator assembly1030may lack degrees of freedom corresponding to yaw and pitch movements, or may lack degrees of freedom corresponding to two translational movements, etc. Accordingly, the subset includes instructions for controlling only those degrees of freedom that the manipulator assembly1030is configured to have. In this case, the instructions are indicative of a desired position of the joints of manipulator assembly1030, and may be combined with information indicating the actual position of the joints of the manipulator assembly1030. The combination may be used to determine the appropriate torque to apply to the joint motors.

In other embodiments, the input device and kinematic model may not have six kinematic degrees of freedom, and the end effector may not have four kinematic degrees of freedom. Rather, the input device and kinematic model may be configured to control a greater number of degrees of freedom than the manipulator assembly is equipped with. For example, the input device1010and controller1020may be configured to control five kinematic degrees of freedom, whereas the manipulator assembly may have anywhere from one to four kinematic degrees of freedom.

FIG. 10Bis a block diagram showing a simplified system1001for controlling a manipulator assembly using an input device in accordance with a second embodiment. System1001includes an input device1010, a controller1020, and a manipulator assembly1030, which may be similar to those discussed with reference toFIG. 10A.

In accordance with this embodiment, the input device1010and controller1020are operable to control a greater number of kinematic degrees of freedom than the manipulator assembly1030has, similar to the embodiment discussed with reference toFIG. 10A. Further, the input device1010is operable to actuate a non-kinematic degree of freedom of the manipulator assembly1030. For example, the input device1010may be operable to actuate a vacuum pressure associated with the manipulator assembly1030.

Accordingly, in this embodiment, the input device1010includes six kinematic degrees of freedom1012as well as at least one actuation degree of freedom1014, where the actuation degree of freedom refers to a non-kinematic degree of freedom. In one embodiment, the actuation degree of freedom may be actuated via an element on the input device1010such as one or more grip members723(FIG. 7B). The input device1010, via the six kinematic degrees of freedom, may then output parameters or other information corresponding to the position of the input device1010or otherwise indicating a desired position of an end effector associated with the manipulator assembly1030. Further, the input device1010, via the one actuation degree of freedom, may output parameters or other information for actuating a functionality of the manipulator assembly1030or a tool coupled to or part of manipulator assembly1030(e.g., actuating a vacuum, one or more pincers/fingers, etc.).

The output from the input device1010are received and processed by the controller1020to provide instructions for controlling the manipulator assembly1030. In this embodiment, the controller1020includes a kinematic model1022of a manipulator assembly having six kinematic degrees of freedom, similar to that described with reference toFIG. 10A. Further, the controller1020also includes an actuation controller1024which may be operable to process the output from the input device1010concerning the actuation degree of freedom1014and use this output to actuate a function of the manipulator assembly1030.

A subset of the results from applying the output from the input device1010to the kinematic model1022are then used to control the manipulator assembly1030, similar to that discussed with reference toFIG. 10A. Further, the results from applying the actuation output from the input device1010to the actuation controller1024may be used to control actuation of the manipulator assembly1030(or actuation of a tool coupled to or part of manipulator assembly1030). As discussed with reference toFIG. 10A, in other embodiments, the input device and kinematic model may not have six kinematic degrees of freedom, and the end effector may not have four kinematic degrees of freedom. Further, in some embodiments, the input device1010may include a plurality of actuation degrees of freedom, the actuation controller1024may be operable to process the output for a plurality of actuation degrees of freedom from the input device1010, and the manipulator assembly1030may have a corresponding number of actuation degrees of freedom that may be controlled by the input device1010separate from the control of the manipulator assembly1030.

FIG. 10Cis a block diagram showing a simplified system1002for controlling a manipulator assembly using an input device in accordance with a third embodiment. System1002includes an input device1010, a controller1020, and a manipulator assembly1030, which may be similar to those discussed with reference toFIG. 10A.

In accordance with this embodiment, the manipulator assembly1030has a number of kinematic degrees of freedom (e.g., eight), which includes at least one null space degree of freedom (e.g., three null space degrees of freedom), but still lacks at least one of the degrees of freedom necessary to fully define the position of an end effector associated with the manipulator assembly1030. For example, although the manipulator assembly1030includes eight kinematic degrees of freedom including redundant degrees of freedom, it still lacks at least one independently controllable rotation or translation degree of freedom.

It should be recognized that when null space degrees of freedom of a manipulator assembly are described herein, it is assumed that the control frame is located on the manipulator assembly (e.g., the control frame is located at a tool tip). However, embodiments are not limited to such cases, and thus where null space degrees of freedom of a manipulator assembly are described, embodiments alternatively include null space degrees of freedom of a Jacobian, where the Jacobian is associated with the manipulator assembly and a control frame having an arbitrarily defined location, such as at a tissue of a patient, at a fixed distance from the tool tip, etc.

The input device1010includes six kinematic degrees of freedom1012similar to those discussed with reference toFIG. 10A. The controller1020is then operable to process the output from the input device1010by applying the output to a kinematic model1026including nine kinematic degrees of freedom, which includes six kinematic degrees of freedom such as those discussed with reference toFIG. 10Aas well as three null space degrees of freedom. The controller1020may thus generate outputs on the assumption that the manipulator assembly1030includes nine kinematic degrees of freedom that include three null space degrees of freedom. However, since the manipulator assembly1030only includes eight kinematic degrees of freedom, the controller1020does not provide an output corresponding to the missing kinematic degree of freedom of the manipulator assembly1030. Rather, the controller1020outputs instructions for controlling the eight kinematic degrees of freedom of the manipulator assembly1030.

FIG. 10Dis a block diagram showing a simplified system1003for controlling a manipulator assembly using an input device in accordance with a fourth embodiment. System1003includes an input device1010, a controller1020, and a manipulator assembly1030, which may be similar to those discussed with reference toFIG. 10A.

In accordance with this embodiment, the input device1010includes one or more null space degrees of freedom, whereas the manipulator assembly1030does not include any null space degrees of freedom and includes fewer kinematic degrees of freedom than the input device1010. In other embodiments, the manipulator assembly1030may also include the same or greater number of null space degrees of freedom as the input device1010.

Accordingly, in this embodiment, the input device1010includes a number of degrees of freedom1016including seven kinematic degrees of freedom which include one null space degree of freedom. The output from the input device1010may then be processed and eventually fed into the controller1020, where the controller1020includes a kinematic model of a manipulator assembly having five degrees of freedom. The controller1020may then apply the output from the input device1010to the kinematic model1028, and then use a subset of the results to control the manipulator assembly1030, similar to that discussed with reference toFIG. 10A.

In this embodiment, the manipulator assembly1030includes four kinematic degrees of freedom1032. However, in other embodiments, the manipulator assembly1030may have fewer than four kinematic degrees of freedom. Further, while the input device1010is described as having one null space degree of freedom, the input device1010may have more than one null space degree of freedom. For example, the input device1010may have two, three, or four null space degrees of freedom.

Systems1000,1001,1002, and1003in certain embodiments are simplified systems for controlling an end effector using an input device and include various components such as an input device1010, controller1020, and manipulator assembly1030. However, it will be appreciated by those of ordinary skill in the art that the systems could operate equally well by having fewer or a greater number of components than are illustrated inFIGS. 10A to 10D. For example, in some embodiments, input devices may have both null space degrees of freedom and actuation degrees of freedom, in addition to one or more kinematic degrees of freedom, controllers may have both null space degrees of freedom and an actuation controller, and manipulator assemblies may have both null space degrees of freedom and actuation degrees of freedom. Thus, the depiction of the systems inFIGS. 10A to 10Dshould be taken as being illustrative in nature, and not limiting to the scope of the disclosure.

FIG. 11Ais a block diagram showing a simplified system1100for controlling a manipulator assembly using a tool position measuring device in accordance with a first embodiment. System1100includes a tool position measuring device1110, a joint estimator1120, and a manipulator assembly1130.

The elements of system1100are similar to the similarly labeled elements of system1000, except that a tool position measuring device1110is provided instead of an input device1010, and a joint estimator1120is provided instead of a controller. Accordingly, the description with reference to system1000is equally applicable to system1100, except in the case of system1100instead of the controller receiving and applying desired position information, the controller receives and applies position measurement information. And, instead of generating desired positions, the joint estimator1120generates actual positions (e.g., joint angles) of the manipulator assembly joints. In some embodiments, the actual positions may be combined with information indicating the desired position of the joints of the manipulator assembly1130. The combination may be used to determine the appropriate torque to apply to the joint motors.

Further, the tool position measuring device1100may only measure five degrees of freedom or less. In this particular embodiment, the tool position measuring device1100is illustrated as measuring five degrees of freedom, however, it may similarly measure four degrees of freedom, three degrees of freedom, or less than three degrees of freedom. And, the joint estimator1120uses only a 5-kinematic DOF model1122which generates only five joint positions, four of which are used (as they correspond to actual joints of the manipulator assembly1130) and one of which is discarded (as there is no corresponding joint in the manipulator assembly1130). In some embodiments, a 6-kinematic DOF model1122could be used in which two joint estimates would then be discarded, or fewer than five kinematic DOF could be used.

FIG. 11Bis a block diagram showing a simplified system1102for controlling a manipulator assembly using a tool position measuring device in accordance with a second embodiment. System1102includes a tool position measuring device1110, a joint estimator1120, and a manipulator assembly1130.

The elements of system1102are similar to the similarly labeled elements of system1002, except that a tool position measuring device1110is provided instead of an input device1010, and a joint estimator1120is provided instead of a controller. Accordingly, the description with reference to system1002is equally applicable to system1102, except in the case of system1102instead of the controller receiving and applying desired position information the joint estimator receives and applies position measurement information. And, instead of generating desired positions, the joint estimator1120generates actual positions (e.g., joint angles) of the manipulator assembly joints. In some embodiments, the actual positions may be combined with information indicating the desired position of the joints of the manipulator assembly1130. The combination may be used to determine the appropriate torque to apply to the joint motors.

Further, in this particular embodiment, the manipulator assembly is shown as having eight kinematic degrees of freedom with multiple pitch and yaw joints. For some embodiments of manipulator assemblies, the manipulator assembly may be logically separated into multiple parts. In the embodiments where optical fiber is used to measure the position and orientation at the end of each part, each part has five or fewer joints or degrees of freedom as the tool position measuring device1112(a) or1112(b) measures five degrees of freedom. The parts may each have the same or different number of degrees of freedom. For example, in this embodiment, the manipulator assembly is logically separated into two parts each having four degrees of freedom.

In at least one embodiment, the number of joints in each part may be maximized prior to incorporating joints into other parts. For example, for a manipulator assembly having seven degrees of freedom, one part may have five degrees of freedom (i.e., the maximum number) and another part may have the remaining degrees of freedom, i.e., two degrees of freedom. For another example, for a manipulator assembly having twelve degrees of freedom, two parts may each have five degrees of freedom, while a third part has only two degrees of freedom. In some cases, joint angles for one or more parts may be computed using geometries rather than inverse kinematics, where it is more computationally efficient to do so. For example, it may be more computationally efficient to use geometries over inverse kinematics when calculating joint estimations for a part having a number of degrees of freedom equal to or less than two.

The tool position measuring device1110may be operable to measure a position for each logical part of the manipulator assembly. For example, the tool position measuring device1110may measure a tip position of the first part and a tip position of the second part. The tip position of each part may be measured in the same or different number of degrees of freedom, where the measured degrees of freedom may be less than, the same, or greater than the degrees of freedom of the corresponding part. In this particular example, the tip position of the first part is measured in five degrees of freedom1112(a), and the tip position of the second part is similarly measured in five degrees of freedom1112(b). It should be recognized that these need not be the same, and in some embodiments may be any number less than five.

The joint estimator1120may then include a kinematic model for each logical part of the manipulator assembly. In this embodiment, joint estimator1120includes a first kinematic model1126(a) and a second kinematic model1126(b). The first kinematic model1126(a) is a kinematic model of the first part of the manipulator assembly1130, and the second kinematic model1126(b) is a kinematic model of the second part of the manipulator assembly1130. Each kinematic model receives the output from the tip measurement corresponding to its respective manipulator assembly part. For example, the output of the first measurement1112(a) is applied to the first kinematic model1126(a), and the output of the second measurement1112(b) is applied to the second kinematic model1126(b). The first kinematic model1126(a) then outputs the actual position of the first part of the manipulator assembly1130, whereas the second kinematic model1126(b) outputs the actual position of the second part of the manipulator assembly1130.

It should be apparent that the degrees of freedom of at least one of the kinematic models1126(a) and1126(b) may be greater than the actual number of degrees of freedom of the corresponding manipulator assembly part. In this particular embodiment, although not necessary, both kinematic models have a greater number of degrees of freedom than their corresponding manipulator assembly part. That is, the first kinematic model1126(a) has five degrees of freedom whereas the first part of manipulator assembly1130only has four degrees of freedom, and likewise for the second kinematic model1126(b) and second part of manipulator assembly1130. This extra degree of freedom is used to generate an output but, similar to other extra kinematic model degrees of freedom described herein, is not subsequently used to determine the actual position of the manipulator assembly parts.

It should be recognized that while the systems described with reference toFIGS. 11A and 11Bare considered similar for purposes of description, the embodiments described with reference toFIGS. 10A to 10Dare directed to systems for generating desired positions of manipulator assembly joints, whereas the embodiments described herein with reference toFIGS. 11A and 11Bare directed to systems for generating actual positions of manipulator assembly joints. In some embodiments and as already described, these systems may be combined into one system. For example, the input device and controller ofFIGS. 10A to 10Dmay be used to generate a desired position, the tool position measuring device and joint estimator ofFIGS. 11A and 11Bmay be used to generate an actual position, and these generated positions may be used in combination as described with reference toFIG. 9.

FIG. 12Ais a manipulator assembly1200according to an embodiment. Manipulator assembly1200may be similar to manipulator assembly1130described with reference toFIG. 11B. Manipulator assembly1200includes a number of links1202and a number of joints1204. The manipulator assembly1200is logically separated into a first part1206and a second part1208. The first part1206extends from a point on the manipulator assembly, farthest from the free end of the manipulator assembly, that is defined as the base1210. The first part1206extends from the base1210to a point within the manipulator assembly identified as the tip position of the first part1212. The second part1208then extends from the tip position of the first part1212to a point defined as the tip position of the second part1214which, in this example, is located at the free end of the manipulator assembly1200.

A number of joints are located within the first part1206and a number of different joints are located within the second part1208. The number may not be the same, but in this example each of the first and second part include four joints. In other examples, where the total number of joints is eight, the first and second parts may respectively include five and three, or three and five joints. Various other combinations for manipulator assemblies having more than five joints may also be implemented. Further, the manipulator assembly may be logically separated into more than two parts. For example, when the total number of joints is eight, a first part may have five joints, a second part may have two joints, and a third part may have one joint. In most embodiments, when a joint estimation technique is used in which the tool position measurement device can only provide N degrees of freedom measurement, then each part includes no more than N joints or degrees of freedom. Further, when a manipulator assembly includes more than N kinematic degrees of freedom, those degrees of freedom are separated into multiple logical parts. In one embodiment, where a fiber optic approach is used in which estimation of the roll orientation is not available, then each part may include no more than five joints or kinematic degrees of freedom.

Turning briefly toFIG. 12B,FIG. 12Bdepicts a block diagram1250illustrating the calculation of joint positions of multiple manipulator assembly parts according to an embodiment. A joint estimator1252in this example includes a first kinematic model1254and a second kinematic model1256. The first kinematic model1254is a kinematic model of the first segment or part of the manipulator assembly. For example, this may be a kinematic model of first part1206. The second kinematic model1256is a kinematic model of the second segment or part of the manipulator assembly. For example, this may be a kinematic model of second part1208.

Each of the kinematic models includes a phantom degree of freedom; that is, a degree of freedom that does not exist in the corresponding part of the manipulator assembly. For example, in the embodiment depicted inFIG. 12A, each of the kinematic models may include a phantom roll degree of freedom as the estimation of the roll orientation may not be available when using the fiber optic approach. In other embodiments, however, one or more of the kinematic models may include more than one phantom degree of freedom. In some embodiments, only one kinematic model includes a phantom degree of freedom.

The tip position of the first segment is input into the first kinematic model1254. For example, the tip position1212may be input into first kinematic model1254. The output from first kinematic model1254is the joint positions of first segment1206(as well as one set of outputs, corresponding to the phantom degree of freedom, that can be ignored). The difference between the tip position of the first segment (e.g., tip position1212) and the tip position of the second segment (e.g., tip position1214) is input into the second kinematic model1256. The output from second kinematic model1256is the joint positions of second segment1208(as well as one set of outputs, corresponding to the phantom degree of freedom, that can be ignored).

FIG. 13is a flowchart showing a process1300for controlling manipulator arms, tools, and/or end effectors using an input device according to a first embodiment. The manipulator arms, tools, and/or end effectors may be any of those described herein, such as manipulator arms100(FIG. 4), manipulator arms500(FIG. 5), tools26(FIG. 1A), surgical tool600(FIG. 6A), endoscope620(FIG. 6B), overtube630(FIG. 6C), actuators830and/or mechanical body840(FIG. 8), etc. The input device may be any of the input devices described herein, such as input device36(FIG. 2), input device700(FIGS. 7A to 7C), input device810(FIG. 8), etc. Further, the process1000may be performed by any of the controllers described herein, such as the control system discussed with reference toFIG. 7A, kinematic processor820(FIG. 8), and/or any other suitable controller provided in any suitable component of MIRS system10(FIG. 1), such as the surgeon's console16, electronics cart24, and/or patient side cart22.

In one particular embodiment, kinematic degrees of freedom of a manipulator assembly may be controlled by driving one or more joints via the controller using motors of the system, the joints being driven according to coordinated joint movements calculated by a processor of the controller. Mathematically, the controller may perform at least some of the calculations of the joint commands using vectors and/or matrices, some of which may have elements corresponding to configurations or velocities of the joints. The range of alternative joint configurations available to the processor may be conceptualized as a joint space. The joint space may, for example, have as many dimensions as the manipulator assembly has degrees of freedom, and in some exemplary embodiments, the joint space may have more dimensions than the manipulator assembly has degrees of freedom as the manipulator assembly may lack at least one degree of freedom necessary to fully define the position of an end effector associated with the manipulator assembly. Further, a particular configuration of the manipulator assembly may represent a particular point in the joint space, with each coordinate corresponding to a joint state of an associated joint of the manipulator assembly where an associated joint of the manipulator exists.

In an exemplary embodiment, the system includes a controller in which a commanded position and velocity of a feature in the work-space, denoted here as its Cartesian space, are inputs. The feature may be any feature on the manipulator assembly or off the manipulator assembly which can be used as a control frame to be articulated using control inputs. An example of a feature on the manipulator assembly, used in many examples described herein, would be the tool-tip. Another example of a feature on the manipulator assembly would be a physical feature which is not on the tool-tip, but is a part of the manipulator assembly, such as a pin or a painted pattern. An example of a feature off the manipulator assembly would be a reference point in empty space which is exactly a certain distance and angle away from the tool-tip. Another example of a feature off the manipulator assembly would be a target tissue whose position relative to the manipulator assembly can be established. In all these cases, the end effector is associated with an imaginary control frame which is to be articulated using control inputs. However, in the following, the “end effector” and the “tool tip” are used synonymously. Although generally, there is no closed form relationship which maps a desired Cartesian space end effector position to an equivalent joint-space position, there is generally a closed form relationship between the Cartesian space end effector and joint-space velocities. The kinematic Jacobian is the matrix of partial derivatives of Cartesian space position elements of the end effector with respect to joint space position elements. In this way, the kinematic Jacobian captures the kinematic relationship between the end effector and the joints of the manipulator assembly. In other words, the kinematic Jacobian captures the effect of joint motion on the end effector. The kinematic Jacobian (J) can be used to map joint-space velocities (dq/dt) to Cartesian space end effector velocities (dx/dt) using the relationship below:
dx/dt=Jdq/dt
Thus, even when there is no closed-form mapping between input and output positions, mappings of the velocities can iteratively be used, such as in a Jacobian-based controller, to implement a movement of the manipulator from a commanded user input. However, a variety of implementations can be used. Although many embodiments include a Jacobian-based controller, some implementations may use a variety of controllers that may be configured to access the Jacobian to provide any of the features described herein.

One such implementation is described in simplified terms below. The commanded joint position is used to calculate the Jacobian (J). Each time step (Δt) calculates a Cartesian space velocity (dx/dt) to perform the desired move (dxdes/dt) and to correct for built up deviation (Δx) from the desired Cartesian space position. This Cartesian space velocity is then converted into a joint-space velocity (dq/dt) using the pseudo-inverse of the Jacobian (J#). The resulting joint-space commanded velocity is then integrated to produce joint-space commanded position (q). These relationships are listed below:
dx/dt=dxdes/dt+kΔx(1)
dq/dt=J#dx/dt(2)
qi=qi-1+dq/dtΔt(3)

The pseudo-inverse of the Jacobian (J#) directly maps the desired tool tip motion (and, in some cases, a remote center of pivotal tool motion) into the joint velocity space. If the manipulator assembly being used has more useful joint axes than tool tip (i.e., end effector) degrees of freedom (up to six), (and when a remote center of tool motion is in use, the manipulator assembly should have an additional 3 joint axes for the 3 degrees of freedom associated with location of the remote center), then the manipulator assembly is said to be redundant. A Jacobian associated with a redundant manipulator assembly includes a “null-space” having a dimension of at least one. In this context, the “null-space” of the Jacobian (N(J)) is the space of joint velocities which instantaneously achieves no tool tip motion (and when a remote center is used, no movement of the pivotal point location), and “null-motion” is the path of joint positions which also produces no instantaneous movement of the tool tip and/or location of the remote center. Incorporating or injecting the calculated null-space velocities into the control system of the manipulator assembly to achieve the desired reconfiguration of the manipulator assembly (including any reconfigurations described herein) changes above equation (2) to the following:
dq/dt=dqperp/dt+dqnull/dt(4)
dqperp/dt=J#dx/dt(5)
dqnull/dt=(I−J#J)z=VnVnTz=Vnα  (6)

The joint velocity according to Equation (4) has two components: the first being the null-perpendicular-space component, the “purest” joint velocity (shortest vector length) which produces the desired tool tip motion (and when the remote center is used, the desired remote center motion); and the second being the null-space component. Equations (2) and (5) show that without a null-space component, the same equation is achieved. Equation (6) starts with a traditional form for the null-space component on the left, and on the far right side, shows the form used in an exemplary system, wherein (Vn) is the set of orthonormal basis vectors for the null-space, and (α) are the coefficients for blending those basis vectors. In some embodiments, α is determined by knobs that are used to shape the motion within the null-space as desired.

As previously mentioned, fully controlling the position of a rigid body requires six independently controllable degrees of freedom, three for translations and three for orientations. This lends itself nicely to a Jacobian based control algorithm, such as that discussed above, in which a 6×N Jacobian matrix is used. However, some rigid bodies lack at least one of these degrees of freedom. For example, a rigid endoscope tip without an articulating wrist is missing two degrees of freedom at the wrist, specifically wrist pitch and yaw. So it only has four degrees of freedom at the tip. This creates a problem for the 6×N Jacobian approach, because the problem is now overconstrained. Using the 6×N Jacobian based controller, when the endoscope tip is commanded to either pan or tilt, since it has a non-wristed tip, it can only do one thing, and this is to do a combination of both. This results in a sluggish unresponsive feel which is undesirable. Accordingly, not only is it desirable to obviate this unresponsive feel, it is also desirable to use a 6×N Jacobian approach because then the same computation engine and/or kinematic model that is used for other arms and instruments can also be used for the camera arm as well.

Accordingly, in some embodiments, Equations (2) and (3) discussed above may be modified. First, Equation (2) may be modified by using a number of phantom degrees of freedom corresponding to the missing degrees of freedom of the controlled mechanical body. This would extend the length of the (dq/dt) vector to equal to the sum of the numbers of existing degrees of freedom plus phantom degrees of freedom. For example, phantom degrees of freedom may be included in Equation (2), where those phantom DOF may be operable to control the wrist pitch and yaw for controlling the above-described endoscope. By using phantom degrees of freedom, the Jacobian based controller is faked into doing the pseudo-inverse calculation for a full six degree of freedom endoscope tip, i.e., a wristed endoscope. The output of this is a set of joint velocities for controlling a six degree of freedom endoscope, even though the actual endoscope being controlled only has four independently controllable degrees of freedom.

Second, in accordance with Equation (3), the joint positions are calculated by integrating joint velocities. However, Equation (3) may be modified such that the velocities of the phantom degrees of freedom, e.g., the nonexistent endoscope wrist joints, are not integrated and therefore remain at a fixed position. In some embodiments, the fixed or desired position may be set to any suitable value independent of a pose of the manipulator. For example, the fixed position may be set to 0 degrees, 15 degrees, 30 degrees, 45 degrees, a value in the range of 0 degrees to 45 degrees, a value less than 0 degrees or a value greater than 45 degrees.

By modifying Equations (2) and (3) for the control algorithm discussed above, in the embodiment concerning the endoscope the endoscope tip may consequently follow an instructed command well without unnecessary sluggishness. The unwristed endoscope has no wrist joints to actuate, and therefore the wrist may stay straight. Further, if there is a force reflection from the slave back to the masters, then the masters may be commanded to follow the straight tip of the endoscope, advantageously resulting in intuitive behavior.

In some embodiments, a pitch and yaw of the endoscope may be independently controlled, but the endoscope may not be able to independently roll. In response to an instruction to pan, a tip of the endoscope may be panned using only the pitch and yaw degrees of freedom. By using pitch and yaw, instead of translations and roll, the endoscope may be controlled to pan while substantially maintaining a location at an aperture of the patient. For example, the endoscope may be controlled to pan without increasing the size or placing pressure on an aperture of the patient through which the endoscope is disposed. This may be done, for example, by pivoting the endoscope about a pivot point at the aperture (i.e., access site).

It should be recognized that advantages are not limited to increasing the responsiveness of controlled tools and increasing the flexibility of the system by using the same controller to operate tools having different degrees of freedom. Rather, in some embodiments, advantages may be realized where tools may be actuated without requiring any additional degrees of freedom on an input device.

For example, in some embodiments, there may only be four inputs at the manipulator assembly, where three are typically used to control movement such as roll, pitch, and yaw, and the fourth is typically used to control a single actuation of an instrument (e.g. suction activation). However, it may be desired to control two actuations of an instrument (e.g., suction activation and irrigation activation) using the same number of inputs at the manipulator assembly. By using a kinematic model that calculates tool instructions using all three kinematic degrees of freedom, i.e., roll, pitch, and yaw, but then discarding one of the outputs, such as roll, motion of the tool may be controlled using only two inputs, i.e., pitch and yaw. The other two inputs may then be used to control two actuations of the instrument, such as suction activation and irrigation activation. Accordingly, although the instrument has only four degrees of freedom in total, including both movement and actuation degrees of freedom, as a result of using phantom degrees of freedom in the controller, the instrument appears to have five degrees of freedom. In some embodiments, phantom degrees of freedom may be used on axially symmetrical instruments, which may advantageously further increase the illusion to the operator of the system (e.g., a surgeon) that they are controlling a degree of freedom which actually may not exist in the instrument.

Returning now toFIG. 13, in operation1310, the controller calculates the forward kinematics from the manipulator's joint positions. As a result of this calculation, the controller determines the commanded Cartesian space velocity (dxdes/dt), the commanded Cartesian space position (xdes), the actual Cartesian space position (x), and the error between the latter two (dx=xdes−x). To calculate the forward kinematics, the controller may use the previously commanded joint position (e.g., the variable (q) calculated in an immediately preceding time step). In operation1320, the controller calculates the desired move (dx/dt) using Equation (1). To calculate the desired move, the controller may use the output from step1310as well as the commanded end effector position (xdes). In operation1330, the controller calculates the Jacobian (J), where calculating the Jacobian (J) uses the previously commanded joint position (q). In operation1340, the controller calculates the pseudo-inverse of the Jacobian (J#).

In operation1350, the controller calculates the joint-space velocity (dq/dt) using the pseudo-inverse of the Jacobian (J#) calculated in operation1340and using the desired move (dx/dt) calculated in operation1320. The pseudo-inverse of the Jacobian in this operation includes phantom degrees of freedom as previously discussed. That is, the pseudo-inverse of the Jacobian includes mathematical representations of degrees of freedom of a mechanical body even though those degrees of freedom may not actually exist on the mechanical body being controlled by the controller. Then, in operation1360, the controller calculates the joint-space commanded position (q) using Equation (3) and the joint-space velocity (dq/dt) calculated in operation1350. However, as previously discussed, the velocities of the phantom degrees of freedom are not integrated in this operation and thus remain at (or may be set to) a fixed position.

Those skilled in the art would recognize that the operations discussed with reference toFIG. 13may be executed frequently so as to provide real-time control of an instrument responsive to a user input. For example, the operations may be performed a plurality of times each second, in some embodiments about 1,000 times per second, 1,300 times per second, 1,500 times per second, in a range from 1,000 times per second to 1,500 times per second, less than 1,000 times per second or more than 1,500 times per second.

It should be appreciated that the specific operations illustrated inFIG. 13provide a particular method of controlling manipulator arms, tools, and/or end effectors, according to certain embodiments of the present invention. Other sequences of operations may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the operations outlined above in a different order. Moreover, the individual operations illustrated inFIG. 13may include multiple sub-operations that may be performed in various sequences as appropriate to the individual operation. Furthermore, additional operations may be added or existing operations removed depending on the particular applications. One of ordinary skill in the art would recognize and appreciate many variations, modifications, and alternatives.

FIG. 14is a flowchart showing a process1400for controlling manipulator arms, tools, and/or end effectors using an input device according to a second embodiment. The manipulator arms, tools, etc., input device and controller for executing the process1400, may be similar to those described above with reference toFIG. 13, and thus further details are omitted.

In contrast to the process1300described with reference toFIG. 13, the process1400may be operable to calculate and control a null space of a Jacobian associated with a manipulator assembly. For example, the manipulator assembly may have one or more redundant degrees of freedom, but may still use one or more phantom joints where the manipulator assembly, even with its redundant degrees of freedom, lacks one or more of those degrees of freedom necessary to fully define the position of an end effector or tool.

Operations1410to1440are similar to operations1310to1340described with reference toFIG. 13, and thus further description is omitted. In operation1450, the controller calculates the joint velocity component within the null-perpendicular-space (dqperp/dt) using the pseudo-inverse of the Jacobian (J#) calculated in operation1440and the Cartesian space velocity (dx/dt) calculated in operation1420. In operation1460, the controller calculates the joint velocity component within the null-space (dqnull/dt) using the Jacobian calculated in operation1430and the pseudo-inverse of the Jacobian (J#) calculated in operation1440and shown in Equation (6), or in some embodiments, using the singular value decomposition of the Jacobian (SVD(J)) or, in some embodiments, using the null-space basis vectors (Vn) and blending coefficients (α) as shown in Equation (6), or using any other equivalent technique. In at least one embodiment, the output of operation1450may be used to calculate the joint velocity component within the null-space (dqnull/dt) operation1460. Similar to that discussed with reference to operation1350and Equation (2), the joint velocity component within the null-perpendicular-space (dqperp/dt) and the joint velocity component within the null-space (dqnull/dt) may be calculated using phantom degrees of freedom in the Jacobian (e.g., in the pseudo-inverse of the Jacobian). Accordingly, each of these components of the joint-space velocity may be calculated using a Jacobian that mathematically represents degrees of freedom that may not actually exist in the controlled manipulator.

In operation1470, the controller calculates the commanded joint-space velocity (dq/dt) by summing the joint velocity component within the null-perpendicular-space—(dqperp/dt) and the joint velocity component within the null-space (dqnull/dt) components calculated in operations1450and1460and as shown in Equation (4). Since each of the components of the commanded joint-space velocity (dq/dt) were calculated to include one or more phantom degrees of freedom, the resulting joint-space velocity (dq/dt) also includes one or more phantom degrees of freedom. Operation1480is then similar to operation1360described with reference toFIG. 13, and thus further description is omitted.

It should be appreciated that the specific operations illustrated inFIG. 14provide a particular method of controlling manipulator arms, tools, and/or end effectors, according to certain embodiments of the present invention. Other sequences of operations may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the operations outlined above in a different order. Moreover, the individual operations illustrated inFIG. 14may include multiple sub-operations that may be performed in various sequences as appropriate to the individual operation. Furthermore, additional operations may be added or existing operations removed depending on the particular applications. One of ordinary skill in the art would recognize and appreciate many variations, modifications, and alternatives.

One skilled in the art would also recognize that while the processes ofFIGS. 13 and 14were described with reference to embodiments where input information is a desired position and comes from an input device (like the embodiments described with reference toFIGS. 10A to 10D), the processes may equally be applicable to embodiments where input information is an actual position and comes from a tool position measuring device (like the embodiments described with reference toFIGS. 11A and 11B). In such embodiments, instead of using a commanded end effector position (xdes) (e.g., as an input to operations1320and1420), an actual end effector position would be used. And instead of generating a commanded joint position (q) (e.g., as an output of operation1360and1480), an actual joint position would be generated.

The operations described in this application may be implemented as software code to be executed by one or more processors using any suitable computer language such as, for example, Java, C, C++ or Perl using, for example, conventional, sequential, or object-oriented techniques. The software code may be stored as a series of instructions, or commands on a computer-readable medium, such as a random access memory (RAM), a read-only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, flash memory, or an optical medium such as a CD-ROM. Any such computer-readable medium may also reside on or within a single computational apparatus, and may be present on or within different computational apparatuses within a system or network.

The present invention can be implemented in the form of control logic in software, firmware, or hardware or a combination of these. The control logic may be stored in an information storage medium as a plurality of instructions adapted to direct an information processing device to perform a set of steps disclosed in embodiments of the present invention. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will appreciate other ways and/or methods to implement the present invention.

Preferred embodiments are described herein, including the best mode known to the inventors. 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 embodiments to be constructed otherwise than as specifically described herein. Accordingly, suitable embodiments include 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 contemplated as being incorporated into some suitable embodiment unless otherwise indicated herein or otherwise clearly contradicted by context. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the pending claims along with their full scope or equivalents.