Minimally invasive surgery techniques reduce the amount of extraneous tissue that are damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects, such as infection. Millions of the surgeries performed each year in the United States can be performed in a minimally invasive manner. However, far fewer of the surgeries performed currently use these techniques, due to limitations in minimally invasive surgical instruments and techniques and the additional training required to master them.
Advances in MIS technology could have a dramatic impact. The average length of a hospital stay for a standard surgery may be double that for the equivalent minimally invasive surgery. Thus, an increase of use of minimally invasive techniques could save many millions of hospital days and attendant costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work are also reduced with minimally invasive surgery.
Endoscopy, a variety of MIS, generally refers to inserting tools into the body through natural orifices. Laparoscopy, another variety of MIS, refers to inserting tools through tiny incisions with sealed ports. In standard laparoscopic surgery, as shown schematically with reference to FIG. 1, a patient""s abdomen is insufflated with gas, and cannula sleeves 510 are passed through small (approximately xc2xd inch (1 cm.)) incisions in the body wall 512 to provide entry ports for laparoscopic surgical instruments 514. The cannula holes may be created by a sharp pointed trocar, which may be equipped with an integral cannula. The following discussions are generally cast in terms of laparoscopy. However, the general principles apply to endoscopy also, and to most MIS.
The MIS instruments generally include a scope (endoscope or laparoscope), for viewing the surgical field, and working tools, such as blunt probes, dissectors, clamps, graspers, scissors, staplers, and needle holders. The working tools are similar to those used in conventional (open) surgery, except that, as shown in FIG. 1, the working end 516 of each tool is separated from its handle end 518 by an approximately 12-inch (30 cm) long extension tube 520. The view is typically displayed on a monitor.
To perform MIS procedures, the surgeon passes instruments through the cannula 510 and manipulates them inside the body by sliding them in and out through the cannula, along the z axis, as shown, rotating them in the cannula around the z axis, levering (i.e., pivoting around the x and y axes, as shown) the instruments in the body wall 512 and operating end effectors (not shown) on the distal end 516 of the instruments. The instruments pivot around centers of rotation approximately defined by the incisions in the muscles of the body wall 512.
The tools are selected from among a family of approximately 33 cm long, 5-10 mm diameter surgical instruments. During the operation, the surgeon is frequently working with two toolhandles, while looking away from the patient at a television monitor, which displays the internal worksite image provided by the scope camera.
A representative handle end 518, with a cover piece removed, is shown with reference to FIG. 2, and a representative scissor tool end 516 is shown with reference to FIG. 3. An outer shaft 524 is connected to two jaws 86a and 86b, which are both also hingedly connected to an inner shaft 526, such that when the shafts translate relative to each other, the jaws open, or close, depending upon the direction of relative motion. This type of linkage can be used with grippers, scissors, or other types of jawed tools. There are also other types of linkages. However, in general, all have a relative translation of two shafts that causes opening and closing of gripper or cutting jaws. Typically jawed instruments have two jaws, however, there can be more than two, such as when several jaws are attached to a collar, and are closed by retraction into a narrow sleeve.
In general, the handle 518 incorporates a lever 522, which amplifies the force applied by the human hand by a factor of around four, and transmits this force to the inner shaft 526, which runs the length of the tool to the working end 516. The travel extent of the inner shaft 526 depends on the individual lever design for the brand of tool, typically between 1 and 8 mm. The finger loops 528a and 528b of the handle 518 may be decoupled from the twisting of the outer and inner shafts 524, 526 about their long (parallel to the z) axis. Twisting can be controlled by placing the index finger on a wheel 534 at the top of the shaft. Typically, the inner shaft 526 is coupled to one 528a of the two handles through a ball joint 532 and the outer shaft 524 is held translationally in place by the wheel 534, which has an internal flange that mates with the outer shaft to fix it translationally. The wheel also has a key on its inside that fits into a slot on the outside of the outer shaft, which key/slot pair couple the shaft and wheel rotationally. The wheel fits in an opening in the handle 528b, with respect to which the wheel and outer shaft can rotate about the z axis, as described above. The two handles 528a and 528b are fixed to each other with respect to rotation around the z axis. A cover to the handle (not shown) is essentially congruent with the larger handle piece 528b, trapping the wheel 534, outer and inner shafts 524 and 526, and the smaller handle piece 528a therebetween.
Thus, the wheel essentially permits decoupling rotation of the outer shaft from rotation of the handle. The inner and outer shafts are coupled to each other in a typical tool by the linkages that join each to the jaws, which are connected to each other such that they rotate with each other. There are some tools that do not have a decoupling wheel, and with those tools, rotating the handle around the shaft axis also rotates the outer shaft.
A typical MIS jawed tool has five degrees of freedom, relative to the axes shown in FIG. 1. These are: translation along the z axis, rotation around the z, x and y axes, and motion of the jaws 86a, 86b relative to each other. The insertion force (z axis), pitch and yaw torques (x and y axes), and the jaw force are all significant in surgery and training. Active twisting around the tool (z) axis is not always applied, but is present in many procedures. Translation along the x and y axes does not occur, due to the constraint of the cannula and the patient""s body wall 512.
Similar MIS techniques are employed in arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy and urethroscopy, just to name a few. The common feature of all of these MIS techniques is that they obtain and display a visual image of a worksite within the human body and pass specially designed surgical instruments through natural orifices or small incisions to the worksite to manipulate human tissues and organs, thus avoiding the collateral trauma caused to surrounding tissues, which would result from creating open surgical access. These techniques may be variously referred to herein as minimally invasive surgeries, MIS, generic endoscopies, or key-hole surgeries.
Current MIS technology presents many difficulties. First, the image of the worksite is typically a two-dimensional image displayed on an upright monitor somewhere in the operating room. The surgeon is deprived of three-dimensional depth cues and may have difficulty correlating hand movements with the motions of the tools displayed on the video image. Second, the instruments pivot at the point where they penetrate the body, causing the tip of the instrument to move in the opposite direction to the surgeon""s hand. Third, existing MIS instruments deny the surgeon the flexibility of tool placement available in open surgery. Most MIS tools have rigid shafts and are constrained to approach the worksite from the direction of the small opening. Those that include any articulation have only limited maneuverability. Fourth, the length and construction of many MIS instruments reduces the surgeon""s ability to feel forces exerted by tissues and organs on the end effector of the tool. Fifth, the MIS tools are not visible on the display near to the entry/exit point, and thus the surgeon""s control thereof is blind for a non-negligible distance.
Overcoming these difficulties and achieving expertise in MIS procedures ideally requires extensive training, practice and constant familiarization with conventional and new MIS tools. However, despite surgeons"" adaptation to the limitations of MIS, the technique has brought with it an increase in some complications seldom seen in open surgery, such as bowel perforations due to trocar or cautery injuries. Moreover, one of the biggest impediments to the expansion of minimally invasive medical practice remains lack of dexterity of the surgical tools and the difficulty of using the tools, and the attendant difficulties to learn the techniques.
Presently, training is very limited, frequently characterized as a, xe2x80x9csee one, do one, teach one,xe2x80x9d method, which is restricted by the availability of operations that may be used as teaching cases. Such training places a great deal of pressure on a new surgeon (not to mention a new patient). To the extent that xe2x80x9cpractice makes perfect,xe2x80x9d the dearth of opportunities for high quality practice impedes the path to perfection. There is also pressure to reduce use of animals in training, if at all possible.
Another difficulty with training is that many actual cases that are available for training are unique, and thus do not offer a general teaching vehicle for typical cases. On the other hand, there are a variety of standard techniques that must be mastered and there are always some that are not required for any particular case. On still another hand, training by only a small number of live operations does not offer the trainee exposure to a wide variety of surgical scenarios, conditions, and pathologies that might be found in a real operating room with a real patient, but which are difficult to recreate with a cadaver, such as the onset of internal bleeding. Further, there is limited opportunity to evaluate surgeons in training in a standardized and objective way. There is also no reliable way to quantify the evaluation of surgeons in training.
Other important information that is difficult to obtain at this time are positions and forces that characterize the surgeons"" motions. Such information, including time on task, accuracy, peak force applied, tissue damage, and position error may be potentially used not only to give feedback to the learning surgeons about their performance and progress, but for testing, licensing, and re-validating surgeons. All of the foregoing complications make it difficult to learn and teach MIS techniques.
Thus, there is a great need for a means to teach surgeons these relatively new techniques, without exposing human, or animal patients to undue dangers.
It has been proposed to teach MIS through simulation, of various types. Theoretically, a high fidelity simulation could provide trainees with numerous opportunities for training, performing the same procedure many times. Further, good simulation could simulate many different situations, including the standard, and the non-standard.
Some existing simulation methods use commercially available synthetic (e.g. plastic) torso and organ models for MIS training, as well as cadaver or animal dissection. Synthetic and nonliving tissue can have dramatically different mechanical characteristics than live tissue, and live animal dissections are being phased out for ethical reasons.
The work of doctors at Penn State University College of Medicine revealed that haptic (touch-based) xe2x80x9clearningxe2x80x9d occurs as surgeons learn MIS. Experienced surgeons are much better at identifying shape and consistency of concealed objects using MIS tools than are medical students (Gorman et al, 1999). (References listed here are set forth in full immediately preceding the claims, below.) Given that haptic information is significant in surgery, it follows that providing accurate haptic sensations to surgeons as they practice is essential.
Thus, another type of simulation is to use a haptic user interface, to display tissue property data taken from live human tissue, through a mechanical simulator. This can offer more realistic reaction forces to the student than working with the synthetic or cadaver simulators.
Any simulation system that simulates both the visual and haptic sensations of surgery would include a basic set of elements. Generally speaking, as shown schematically with reference to FIG. 4, these components include a dual function haptid input and display device 40 and a computer 42, which controls the simulation. Graphics display is provided by a visual monitor 44, and haptic display through an electromechanical force-feedback device 40, usually specialized for the type of surgery being simulated. The user interacts with the simulation through the mechanical interface 46, which measures the instrument position in the simulated workspace, and the user manipulable object 718. The computer interfaces with the mechanical interface through an electronic interface 48. It also runs real-time software, which uses the position (and its derivatives) as the input to tissue models based on simple mass-spring-damper relations, finite element methods, or other techniques, to determine the geometric and dynamic behavior of the simulated tissue. These reactions are fed to software loops, which continuously update the commands to both the haptic 40 and graphical 44 display devices.
Extensive effort has gone into developing each of the basic simulator system elements described above. As the present invention was focused most directly on the haptic display device 40, and the mechanical interface 46, it is helpful to discuss significant work in this field.
Force-feedback devices as a field grew out of efforts initiated in the 1950""s and 1960""s to develop xe2x80x9cmasterxe2x80x9d manipulators for telerobotic applications. A human interacts with the master device to control a second, xe2x80x9cslavexe2x80x9d device, which performs a task. Telerobotics are generally implemented in environments unfavorable for human manipulation, due to harmful environmental factors or motion constraints, or for tasks that a robot can be specialized to perform. These input devices took on various forms: devices morphologically similar to the slave, joysticks, exoskeletons which encased the hand or more of the body, and more generalized kinematic configurations. See generally, (Madhani., 1998), (Burdea, 1996).
The observation that human performance could be significantly improved by providing force feedback to the system user led to later efforts to develop masters to interact, not with a distant real environment (more, about which, is discussed below, in connection with telesurgery) but with a simulated or xe2x80x9cvirtualxe2x80x9d environment. This led to the introduction of generalized force-feedback manipulators for virtual reality such as the PHANTOM(trademark) haptic interface, which is the basis for a number of the systems described here (Massie, 1993). These generalized force feedback manipulators can be used with a simulated MIS environment, to provide a training simulator.
The trend of using generalized force-feedback manipulators can be seen for the field of medical robotics in particular. Force feedback telemanipulator systems have been introduced to permit motion scaling and filtering for microsurgery and to relieve the kinematic constraints and potential for fatigue on the surgeon in laparoscopy. Examples include an opthalmic telerobotic system developed by Ian Hunter at Massachusetts Institute of Technology (xe2x80x9cMITxe2x80x9d) (Hunter, 1995) and a laparoscopic system designed by Akhil Madhani, also then at MIT. (Madhani, 1998).
In such systems, forces reflected to the user can be amplified to effectively give the surgeon a xe2x80x9csuper-humanxe2x80x9d sense of touch and better control when working with delicate tissues. Some efforts to bring force-feedback into the surgery simulation arena have produced a variety of dedicated haptic devices while others, focusing on achieving sophisticated modeling and graphics, have integrated one or more of generalized devices into their simulations. These configurations are, predominantly, three actuated degree-of-freedom devices (pitch, yaw and insertion), which either actuate around the pivot point or apply forces to the tool tip.
Machines that actuate around the pivot point include the commercially available Immersion Impulse Engine, available from Immersion Corporation of San Jose, Calif., and a device developed by Ecole Polytechnique, the Bleuler Lab (Vollenweider, 1999).
Devices that apply forces to the tool tip include the PHANTOM(trademark) Haptic Interface, available from Sensable Technologies, Inc., of Cambridge, Mass. (Massie, 1993), and described in U.S. Pat. No. 5,587,937, among others, issued on Dec. 24, 1996, in the name of Massie et al, and one disclosed in a recent patent assigned to Immersion Corporation (U.S. Pat. No. 5,828,197) (Martin, 1996). Both the 5,587,937 Massie et al. Pat., and the 5,828,197 Immersion Martin ""197 patent are hereby incorporated fully herein by reference.
A modified instance of a PHANTOM(trademark) haptic system, which embodies aspects of the present invention, is shown, in FIG. 5. (Thus, FIG. 5 does not depict prior art. The only aspects of FIG. 5 that are prior art are between the base 51 and the first gimbal link 80.) The PHANTOM(trademark) haptic apparatus is essentially a three DOF manipulator, which is approximately counterbalanced using the weight of two of its own motors 52a and 52b. The standard PHANTOM(trademark) interface uses a passive three DOF gimbal at the end of the actuated three DOF arm 56. Various user manipulable attachments are available, including a stylus and a thimbal. As shown in FIG. 5, the gimbal 54 has only two unactuated DOFs, rather than the standard three. The third DOF is actuated, as used in the present invention, as explained in detail below. A five bar linkage 58 connects the gimbal 54 to the base 60, through the three actuated DOFs.
The Martin ""197 Patent also discloses a device for interfacing the motion of a user with a computer system. A modified instance, which embodies aspects of the present invention is shown, in part FIG. 6. (Thus, FIG. 6 does not depict prior art. The only aspects of FIG. 6 that are prior art are between the base 63 and the first link 64 of the gimbal.) It provides three degrees of freedom to the user manipulable object, similar to the PHANTOM(trademark) haptic interface. Three grounded actuators 64 provide forces in the three degrees of freedom. (In contrast, the PHANTOM(trademark) haptic interface, has one grounded actuator 53 and two moving actuators 52a and 52b, which counterbalance the user-held object.) Two of the Martin ""197. device degrees of freedom are a planar workspace provided by a closed-loop linkage of members 68. The third degree of freedom is rotation of the planar workspace provided by a rotatable carriage 66. Capstan and cable drive mechanisms transmit forces between the actuators 64 and the user object 62. The drums 70 rotate with the carriage while the pulleys and actuators 64 remain fixed to ground. While this configuration is not balanced like the PHANTOM(trademark) interface, it should decrease the inertia of each of the planar linkage axes. The Martin ""197 interface also may include a floating gimbal mechanism coupling the linkage 68 to the user object 62, similar to the PHANTOM interface. One of the user objects shown is a two handled grip 74 that can be used to simulate an MIS handpiece. The Martin ""197 Patent. mentions that it might be possible to actuate motion of the handpiece around the tool""s long axis (z, as shown in FIGS. 1 and 6), but that this is not recommended, as the need is infrequent in surgery, and the cost would entail heavy actuators. The Martin ""197 patent also discloses tracking the relative motion of the two handles, but does not discuss actuating any such motion.
The PHANTOM(trademark) haptic interface and the Immersion Impulse Engine are the two predominant commercially available devices that have been implemented by developers of software simulations to provide force feedback for their systems. Thus, most simulations have feedback to the pitch, yaw, and insertion axes of motion, while the rotation of the tool and the opening and closing of the handles of any gripper/scissors tool, are passive, without actuation or force feedback.
None of the devices described above provide a high fidelity, fully functional simulator for MIS. They do not provide a user interface object that sufficiently replicates the feel and operation of a two (or more) handled gripping/scissoring, tool, such as a gripper, with force feedback upon each of the five DOFs, including the jaw DOF, that are important for such MIS operations.
In addition to the need to train surgeons, there is further the related need to evaluate surgeons as they are learning the MIS techniques, again without endangering patients. Theoretically, a device that simulates MIS could also be used to evaluate trainees, if it could monitor the trainee""s motions and applied forces, relative to the surgical environment. However, because there is no device that accurately simulates all of the conditions of MIS, there is also no device that can accurately monitor and quantify them, in particular, the applied forces.
Another opportunity that such a machine, if it were to exist, would fill, is that of surgical planning for even an experienced MIS practitioner. As new or risky MIS tasks are developed, a surgeon may want to try several alternative approaches before the actual surgery. A high fidelity simulator would provide some opportunity to realize this objective.
As has been mentioned, telesurgery systems 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. xe2x80x9cTelesurgeryxe2x80x9d is a general term for surgical systems where the surgeon indirectly controls surgical instrument movements rather than directly holding and moving the tools. In a system for telesurgery, the surgeon is provided with an image of the patient""s body at the remote location. While viewing the three-dimensional image, the surgeon manipulates a master device, which controls the motion of a servomechanism-actuated slave instrument, which performs the surgical procedures on the patient. The surgeon""s hands and the master device are positioned relative to the image of the operation site in the same orientation as the slave instrument is positioned relative to the act. During the operation, the slave instrument provides mechanical actuation and control of a variety of surgical instruments, such as tissue graspers, needle drivers, etc., which each perform various functions for the surgeon, i.e., holding or driving a needle, grasping a blood vessel or dissecting tissue.
The requirements of a user interface to be used in simulation would also meet many of the requirements of a master to be used in telesurgery.
Such telesurgery systems have been proposed for both open and MIS procedures. An overview of the state of the art with respect to telesurgery technology can be found in xe2x80x9cComputer Integrated Surgery: Technology and Clinical Applicationsxe2x80x9d (MIT Press, 1996).
Proposed methods of performing telesurgery using telemanipulators also create many challenges. One is presenting position, force, and tactile sensations from the surgical instrument back to the surgeon""s hands as he/she operates the telesurgery system, such that the surgeon has the same feeling as if manipulating the surgical instruments directly by hand. For example, when the instrument engages a tissue structure, bone, or organ within the patient, the system should be capable of detecting the reaction force against the instrument and transmitting that force to the surgeon. Providing the master instrument with force reflection helps reduce the likelihood of accidentally damaging tissue in areas surrounding the operation site. Force reflection enables the surgeon to feel resistance to movements of the instrument when the instrument engages tissue.
A system""s ability to provide force reflection is limited by factors such as friction within the mechanisms, gravity, the inertia of the surgical instrument and the size of forces exerted on the instrument at the surgical incision. Even when force sensors are used, inertia, friction and compliance between the motors and force sensors decreases the quality of force reflection provided to the surgeon.
Apparati developed by Madhani can be used as slave devices in a telesurgery system. This work is disclosed in several patents and applications, including three patents, all filed on May 16, 1997, as follows: ARTICULATED SURGICAL INSTRUMENT FOR PERFORMING MINIMALLY INVASIVE SURGERY WITH ENHANCED DEXTERITY AND SENSITIVITY, issued Aug. 11, 1998, as U.S. Pat. No. 5,792,135; WRIST MECHANISM FOR SURGICAL INSTRUMENT FOR PERFORMING MINIMALLY INVASIVE SURGERY WITH ENHANCED DEXTERITY AND SENSITIVITY, issued Aug. 25, 1998 as U.S. Pat. No. 5,797,900; and FORCE-REFLECTING SURGICAL INSTRUMENT AND POSITIONING MECHANISM FOR PERFORMING MINIMALLY INVASIVE SURGERY WITH ENHANCED DEXTERITY AND SENSITIVITY, issued on Sep. 15, 1998 as U.S. Pat. No. 5,807,377. Each of these, in turn, claimed priority to Provisional application No. 60/017,981, described in a PCT application, PCT/US98/19508, filed on Sep. 18, 1998, which designated the United States, entitled ROBOTIC APPARATUS, published on Oct. 7, 1999, as WO 09650721A1. All of the above mentioned Madhani patents and applications are incorporated herein by reference.
The Madhani ROBOTIC APPARATUS invention, in general, concerns a robotic apparatus that has seven actuators and a linkage that actuates a two jawed end effector. Three serial macro freedoms have large ranges of motion and inertias, and four serial micro freedoms, nearest to the effector, have small ranges of motion and inertias. The macro and micro freedoms are redundant. Translation of the end effector in any direction is actuated by at least one micro joint and at least one macro joint. This arrangement facilitates fine control of the force that the end effector applies to its environment. The apparatus can be part of a master and slave combination, providing force feedback without any explicit force sensors. The slave is controlled such that a slave having more DOFs than the master can be controlled. A removable effector unit actuates its DOFs with cables. The Madhani documents describe a master that is based on the PHANTOM(trademark) haptic interface identified above. The Madhani slave can include a pair of endoscopic jaws or blades, such as a gripper or scissors. It also discloses a simple type of two element user interface that is used with a PHANTOM(trademark) haptic interface, shown in FIG. 20 of the ROBOTIC APPARATUS application, which comprises a pair of tweezer-like members that are hinged to each other and coupled to a spring that causes their return to a rest open position. The document mentions generally that they may be actuated by an actuator located at their joint.
What is needed, therefore, for telesurgery is a servomechanical surgical master apparatus that can provide the surgeon with sensitive feedback of forces exerted on the surgical instrument. What is needed for training is a surgical simulator that realistically simulates the conditions of a minimally invasive surgery. Both such systems require a user interface that replicates the tools that the surgeon would use, including a jawed tool, such as a gripper or scissors and that presents to the user the forces that would arise during an actual surgery, including both tool handle open/close forces (e.g., gripper, scissors) and forces that arise upon rotating the tool handle around its long (2) axis. Such a device should feel to the user as real as possible, with as little added friction and inertia as possible, thereby enabling tissue diagnosis and manipulation, both simulated, and telerobotic. It should be possible to incorporate such a device into a simulated model that closely approximates a human body. The device must be robust and must have a range of motion and force possibilities that coincide with those experienced in actual MIS.
In general, a preferred embodiment of the invention is a robotic handle module that actuates handles of a user interface for various types of robotic applications, including MIS. A modified, standard MIS tool handle has a pair of parallel shafts that translate relative to each other upon relative motion of the handles. They are free to rotate relative to each other. A housing engages the two shafts of the tool handle. The first shaft is translationally fixed and rotatably free relative to the housing. The first shaft is coupled to an actuator that actuates rotation of the first shaft relative to the housing. An encoder associated with the actuator measures (indirectly) the rotation of the shaft. The second shaft is coupled to the housing such that it is rotationally fixed about and translatable along the axis of its elongation. The second shaft is fixed to a cartridge that is slidably coupled to the housing. The cartridge constitutes a linear capstan and translates relative to the housing, in response to relative translation of the two shafts. A jaw action actuator is coupled to the cartridge through a cable drive, and can actuate the relative translation of the two shafts, and thus, the two handles. An encoder associated with the jaw action actuator measures (indirectly) the relative translation between the two shafts. Thus, under proper control, the jaw action actuator can actuate jaw action of a tool in a tool environment, either virtual, or actual, as in a slave environment. Thus, the handle module can actuate both the jaw action of a jawed tool, as well as rotation around the long axis of the shafts. The actuation thus may also provide force feedback to the user, for use as a simulator, or telerobotic master.
A preferred embodiment of the invention is a haptic apparatus to interface a human user with a tool environment through the interchange of force. The apparatus comprises a user contact element for physically contacting a body member of the user, the contact element comprising a pair of first and second contact members that are movable relative to each other. The apparatus further comprises a first elongated member that is translationally fixed to the first contact member, and a second elongated member that is parallel with the first elongated member, and that is coupled to the second contact member, such that the second elongated member is translatable relative to the first elongated member upon relative motion of the first and second contact members. The second elongated member is also rotatable relative to the first elongated member upon rotation of the first contact member relative to the second elongated member. The apparatus also includes a first actuator, which is coupled to both of the first and second elongated members, such that upon actuation the first actuator actuates relative translation of the first and second elongated members. The apparatus also includes a second actuator, which is coupled to both of the elongated members, such that upon actuation, the second actuator actuates relative rotation of the first and second elongated members about an axis parallel to their axes of elongation.
In a typical embodiment, the first and second elongated members are substantially concentric shafts, the first being a hollow outer shaft that surrounds the second, which is thus an inner shaft.
The contact element may be a two handled element, with the first and second contact members constituting the handles, being rotatable relative to each other about an axis that is perpendicular to the axis of elongation of the first and second shafts. The handles may be rotatable, like scissors handles, or translatable (as are scissors handles, or, more definitely, as are the two components of a syringe).
In yet another preferred embodiment of the invention, the handle element is a two-handled minimally invasive surgery, handpiece such as is used for endoscopy or laparascopy, including graspers, scissors and grippers.
The apparatus may include displacement sensor arranged upon activation to generate a signal that corresponds to the relative translational and/or rotational displacement between the first and second elongated members.
According to another preferred embodiment, each actuator has a nominally stationary part and a nominally movable part. The apparatus further comprises a housing, to which the stationary part of both actuators are attached, the outer (first) elongated member being rotatably coupled and translatably fixed to the housing and the inner (second) elongated member being rotatably fixed and translatably coupled to the housing.
The rotor of the first actuator may be coupled to the inner elongated member such that actuation of the first actuator actuates relative translation between the inner elongated member and the housing, and thus, between the inner and the outer elongated members. The coupling between the first actuator and the inner elongated member may be a cable transmission that includes a cartridge that is fixed to the inner elongated member, and that is translatably coupled to slide along an axis, relative to the housing, the translation of the cartridge being actuated by the first actuator.
According to still another embodiment, the second actuator is a rotary motor, and is coupled to the outer elongated member, such that the second actuator actuates relative rotation between the outer elongated member and the housing, and thus between the outer elongated member and the inner elongated member.
Yet another preferred embodiment includes first and second displacement sensors arranged upon activation to sense the relative translational and rotational displacement, respectively, between the first and second elongated members, and to generate signals that correspond thereto. The sensors are coupled to a controller that is coupled to the first and second actuators, and that is further arranged, upon activation, to control the first and second actuators based, in part, upon the signals from the displacement sensors.
Typically, the first actuator is arranged with its axis substantially perpendicular to the first elongated member, and the second actuator is arranged with its axis substantially perpendicular to that of the first actuator.
In another preferred embodiment, the controller is configured to actuate the first actuator to present forces to a user engaging the contact members that simulate minimally invasive surgery tool jaws urged against a resisting force, such as a gripper gripping tissue, or spreading apart tissue, or as scissors cutting through tissue. The controller may also be configured to actuate the first actuator to present forces to a user engaging the contact members that are proportional to their relative velocity, thereby simulating a damping factor relative to their motion, or their relative displacement, thereby simulating an elastic spring factor.
According to still an additional preferred embodiment, the invention includes a base mechanical interface unit that comprises an interunit link that is fixed to the housing and a powered base linkage that couples the interunit link to a base foundation. The interunit link is movable through at least five degrees of freedom relative to the base, whereby the powered base linkage is arranged, upon activation, to actuate the interunit link and thus the housing, with respect to at least three degrees of freedom of motion relative to the base foundation. The powered base linkage may be either a tip actuated linkage or a pivot actuated linkage. Examples of tip actuated linkages include a PHANTOM haptic interface, as shown in FIG. 5 herein, or a Martin ""197 haptic interface, as shown in FIG. 6 herein.
In accord with still another preferred embodiment of the invention, the tool environment may be a slave robot that is configured to be operated by the haptic interface apparatus as a master device. The apparatus further comprises a controller coupled to the slave apparatus, configured upon activation to control its motions and a communications channel, coupling the controller for the master apparatus to the controller for the slave apparatus. The slave robot may be a minimally invasive surgery apparatus for use upon a subject, having an end effector with two actuate d members that are movable relative to each other under actuated control, such as grippers or scissor jaws, and which contact the subject in use. The actuated end effector members may further be rotatable together around an axis under actuated control
In line with this embodiment, the haptic interface controller may be further configured to: receive signals through the communications channel from the slave robot that correspond to any force that the actuated end effector members experience if contacting the subject while actuated to move relative to each other; and to actuate the first actuator to actuate relative rotation of the user contact members to present a force to a user in contact with the user contact members that corresponds to any such force that the end effector members experience upon moving relative to each other. Similarly, the controller and components may be further configured to present a force to a user in contact with the user contact element, which corresponds to any force that the end effector members experience upon rotating together.
According to yet another preferred embodiment, the invention is a haptic apparatus to interface a human user with a tool environment through the interchange of force. The apparatus comprises a user contact element for physically contacting a body member of the user. The contact element comprises a two-handled minimally invasive surgery handpiece with a pair of first and second loop handles that are movable relative to each other. The apparatus further comprises a first, outer elongated member that is translationally fixed to the first loop handle and a second, inner elongated member that is concentric with and inside the first elongated member, and that is coupled to the second loop handle, such that the inner elongated member is translatable relative to the outer elongated member upon relative motion of the two loop handles. The outer elongated member is also rotatable relative to the inner elongated member upon rotation of the first loop handle relative to the inner elongated member. The apparatus also comprises an actuator, having a stator and a rotor, which actuator is coupled to both of the outer and inner elongated members, such that upon actuation the actuator actuates relative translation of the inner and outer elongated members. Also part of the apparatus is a housing, to which the stator is attached. The outer elongated member is rotatably coupled and translatably fixed to the housing and the inner elongated member is rotatably fixed and translatably coupled to the housing. The rotor is coupled to the inner elongated member such that actuation of the actuator actuates relative translation between the inner elongated member and the housing, and thus, between the inner and the outer elongated members.
Yet another preferred embodiment of the invention is a minimally invasive surgery simulator apparatus comprising a handle unit, a handle actuation module and a base mechanical interface. The handle unit includes a pair of handles that correspond to handles of a minimally invasive tool and a pair of parallel elongated members that translate relative to each other along their axis of elongation and that rotate relative to each other around the axis of elongation, each being coupled to a respective one of the handles. The handle actuation module comprises a housing. The first elongated member is rotatably coupled and translatably fixed to the housing and the second elongated member is rotatably fixed and translatably coupled to the housing. The handle actuation module also includes a backdrivable first actuator, the stator of which is coupled to the housing, and the moving part of which is coupled to the second elongated member, such that the first actuator actuates relative translation between the pair of elongated members. A sensor generates a signal that corresponds to translation displacement between the two elongated members. The base mechanical interface unit comprises a handle actuation module support, to which the housing is fixed, and a base foundation, coupled to the handle actuation module support, such that the handle actuation module is movable through at least three additional DOFs relative to the base foundation. The base mechanical interface unit also includes a plurality of backdrivable actuators, coupled between the base foundation and the handle actuation module support, such that upon activation, the plurality of actuators actuates motion of the handle actuation module support relative to the base. The base unit also includes a sensor assembly that generates a signal that corresponds to displacement between the handle actuation module support and the base foundation, relative to the at least three additional DOFs
The handle actuation module may further comprise a backdrivable second actuator, the stator of which is coupled to the housing, and the moving part of which is coupled to the first elongated member, such that the second actuator actuates relative rotation between the pair of elongated members. A sensor generates a signal that corresponds to rotational displacement between the two elongated members. A linear capstan may couple the first actuator to the second elongated member and a cable drive and rotary bearing may couple the second actuator to the first elongated member