Patent Description:
Retinal microsurgery, and in particular, vitreoretinal surgery, is among the most challenging ophthalmic surgical procedures. As the name implies, vitreoretinal eye surgery is performed in the gel-like vitreous and on surfaces of the light-sensitive retina within the relatively small ocular space. Common conditions necessitating vitreoretinal surgery include epimacular membranes, vitreomacular schisis, vitreomacular traction syndrome, diabetic traction retinal detachments, proliferative vitreoretinopathy (PVR), retinal detachment, and macular holes, in addition to various treatments such as microinjection procedures for gene therapy and scaffold placements for cell based therapies.

During vitreoretinal surgery, surgeons must perform precise micron-scale maneuvers while applying diminutive forces to retinal tissues beyond the natural human levels of sensory perception. Thus, performance of vitreoretinal surgery is inherently restricted by human sensory and motor limitations, surgeon fatigue and hand tremor, imprecise instrumentation, fine feature sizes, limited manipulation room within the ocular space, and occasionally poor visualization of the interior of the eye. In addition to the above limitations, serious complications may also be caused by involuntary patient eye and/or head movement. The aforementioned factors may contribute to a variety of surgical complications including retinal breaks, retinal detachment, hemorrhage, damage to retinal blood vessels, and damage to the lens resulting in cataracts, many of which can develop into potentially irreversible damage and visual impairment.

Recently, robotically-assisted surgical devices have been developed to assist surgeons in the performance of minimally invasive ophthalmic surgeries, including vitreoretinal surgery. Yet, these robotic devices still suffer from several drawbacks, including the high risk of complications from patient eye movement during surgery.

To minimize this risk, digital eye tracking has been proposed for use by these robotic devices. However, current eye tracking technologies are not advanced enough to detect and correct for sudden head and eye movements, which may be caused by sleep apnea or a startled response upon awakening from sedation.

Furthermore, most current robotic ophthalmic surgical systems do not provide force control (e.g., scaling, limiting, filtering) or force feedback (e.g., tactile feedback) while maintaining a high degree of freedom of movement, and instead typically only provide some form of scaling, thus not effectively addressing the sensory and motor limitations of surgeons. Additional limitations associated with current robotically-assisted surgical devices and systems include limited flexibility and serial kinematics. Current robotic systems are characterized by <NUM> degrees-of-freedom (<NUM>-DOF), which is insufficient to address patient head and/or eye movement or rotate the eye to visualize around corneal or lens opacities, as well as visualize the peripheral retina during ophthalmic procedures. Further, serial robots, such as articulated robotic arms, are disadvantaged by cumulative joint error, kinematic singularities, decreased precision, and decreased speed. Thus, current robotically-assisted surgical devices and systems lack the dexterity to precisely and effectively execute the micron-scale maneuvers regularly performed during vitreoretinal surgery and respond to sudden heady and eye movement of the patient.

Accordingly, there is a need in the art for robotic surgical systems with improved dexterity and accuracy for ophthalmic microsurgical procedures.

Reference is made to the documents <CIT>, <CIT>, <CIT>, <CIT>, and <CIT> which have been cited as relating to the background state of the art.

<CIT> discloses an slave device and method for controlling the same, and eye surgery device and method for controlling the same. The slave device includes a lower delta robot, an upper delta robot, a lower shaft, an upper shaft, a lower gripper, an upper gripper, a surgical tool, a lower frame and an upper frame.

<CIT> discloses a robot-assisted micro-surgical system allowing medical professionals to perform surgery on features that are on the order of microns, comprising a slave hybrid-robot, a tele-robotic master, and a frame that can be attached to the patient's head by a bite plate and a coronal strap.

The present disclosure relates to robotic manipulation systems for surgical procedures, and more particularly, to high dexterity direct drive robotic systems for ophthalmic microsurgical procedures.

In certain embodiments, a surgical system is provided, including a master apparatus and a slave apparatus controllably coupled to the master apparatus and further configured to be mounted to a patient's head. The slave apparatus includes a support frame coupled to a first and second set of three linearly-actuating links, wherein each link of a set is spaced apart from an adjacent link by an angle less than or equal to about <NUM> degrees. The slave apparatus further includes a surgical tool pivotally supported by each of the links, which are configured to provide translational and rotational movement to the surgical tool. The surgical system also includes one or more direct drive actuators coupled to each link of the first and second sets to provide linear movement to the links.

It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

In the following description, details are set forth by way of example to facilitate an understanding of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed implementations are exemplary and not exhaustive of all possible implementations. Thus, it should be understood that reference to the described examples is not intended to limit the scope of the disclosure. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one implementation may be combined with the features, components, and/or steps described with respect to other implementations of the present disclosure.

Note that, as described herein, a distal end or portion of a component refers to the end or the portion that is closer to a patient's body during use thereof. On the other hand, a proximal end or portion of the component refers to the end or the portion that is distanced further away from the patient's body.

As used herein, the term "about" may refer to a +/-<NUM>% variation from the nominal value. It is to be understood that such a variation can be included in any value provided herein.

Embodiments of the present disclosure generally relate to robotic surgical systems for surgical procedures, and more particularly, to high dexterity direct drive robotic systems for ophthalmic microsurgical procedures. In certain embodiments, a robotic surgical system includes a master apparatus controllably coupled to a slave apparatus. The slave apparatus mounts to a patient's head and includes a dual tripod structure having two pluralities of linear actuator links pivotally supporting a surgical tool. The motions of the actuator links are controlled by direct drive actuators to provide at least <NUM>-DOF for the surgical tool. A passive articulating arm having a SCARA (Selectively Compliant Articulated Robot Arm) mechanism and a four-bar parallelogram mechanism attaches to the slave apparatus and counterbalances the weight thereof when mounted on a patient. The surgical system also includes sensors communicatively coupled to the slave apparatus and master apparatus to enable force feedback and force control. Accordingly, the robotic surgical system enhances the dexterity of an operator and enables performance of medical procedures more easily than by hand.

<FIG> illustrates a schematic view of an exemplary robotic surgical system <NUM>, according to certain embodiments described herein. The robotic surgical system <NUM> employs a master-slave type robotic system that includes a master apparatus <NUM> and a slave apparatus <NUM>. The master apparatus <NUM> may be any suitable type of master device characterized by six degrees of freedom (<NUM>-DOF) or seven degrees of freedom (<NUM>-DOF) that has an operator interface. In certain embodiments, the master apparatus <NUM> includes a <NUM>-DOF or <NUM>-DOF haptic interface with low inertia and friction. One such example of a suitable master device with a haptic interface is the Freedom6S haptic device available from MPB Technologies, Inc.

In certain embodiments, the master apparatus <NUM> includes a haptic interface modeled to match (e.g., resemble) the slave apparatus <NUM>. For example, the master apparatus <NUM> may have a structure substantially similar to that of the slave apparatus <NUM>, described in greater detail below. When an operator <NUM> operates the master apparatus <NUM>, the master apparatus <NUM> generates a plurality of signals, herein collectively referred to as a "control signal," that is transmitted between the master apparatus <NUM>, a programmed computer <NUM>, and the slave apparatus <NUM>. Receiving the control signal, the slave apparatus <NUM> controls the manipulation and/or operation of a surgical tool <NUM> directly or indirectly coupled thereto to perform an ophthalmic surgical procedure.

The slave apparatus <NUM>, and therefore the surgical tool <NUM>, are placed over an eye <NUM> of a patient <NUM>, who is shown in <FIG> as lying in a surgical position on an operating table <NUM>. The slave apparatus <NUM> is at least partially supported over the patient's eye <NUM> by a slave apparatus support system <NUM> including a forehead support <NUM> configured to mount to (e.g., rest on) the patient's head. By mounting the slave apparatus <NUM> to the patient's head, the risks associated with uncontrolled patient head movement during a surgical procedure can be greatly reduced or eliminated. The forehead support <NUM> is further coupled to an articulating arm <NUM> employing a passive four-bar parallelogram mechanism counterbalanced by an air spring or constant force spring to alleviate pressure on the patient's head caused by the weight of the slave apparatus <NUM> and forehead support <NUM>. The articulating arm <NUM> may be supported by a base <NUM>, such as a support post, or may extend from another surgical device or a ceiling of an operating room. Further details regarding the slave apparatus <NUM>, forehead support <NUM>, and articulating arm <NUM> are provided below with reference to <FIG>.

The surgical tool <NUM> includes any suitable surgical device or apparatus for ophthalmic surgical procedures, such as vitreoretinal surgical procedures. For example, the surgical tool <NUM> may be a forceps, shaver, shear, cutter, or other non-actuated device. In certain embodiments, the surgical tool <NUM> is configured to perform surgical maneuvers, such as membrane peeling, segmentation, delamination of epiretinal membranes, retinal incisions, subretinal injections, or the like. In certain embodiments, the surgical tool <NUM> includes an end effector having one or more actuators for enabling direct manipulation of the end effector secured thereto.

In certain embodiments, the surgical tool <NUM> includes an end effector having a <NUM>-DOF force/torque sensor (i.e., transducer) incorporated therein to facilitate force feedback and force control by the robotic surgical system <NUM>. In still further embodiments, the surgical tool <NUM> is a device holder or sleeve configured to secure another device or tool to the slave apparatus <NUM>, and includes a radio frequency identification (RFID) or quick response (QR) barcode sensor in communication therewith to communicate tool weight (facilitating a weightless tool), moment arms (facilitating center of gravity compensation as orientation of the surgical tool <NUM> changes in space), and tool length and offsets (facilitating consistent master-slave pose relationship) to the computer <NUM>. Generally, tool actuation pneumatic or hydraulic connections, fiber optic connections, aspiration and/or injection connections, and an uninterruptible power supply connection may be incorporated into the surgical tool <NUM> or bypass the surgical tool <NUM> via service loops.

<FIG> illustrates a perspective view of the slave apparatus <NUM> of the robotic surgical system <NUM>, according to certain embodiments. The slave apparatus <NUM> is configured to be mounted over the patient's eye <NUM> and manipulate and/or operate a surgical tool <NUM> directly or indirectly attached thereto. In the embodiment of <FIG>, the surgical tool <NUM> is coupled to a distal end of a tool shaft <NUM>, which, in certain embodiments, is a device holder or sleeve.

As depicted, the tool shaft <NUM> is movably coupled to two sets 202a, 202b of three radially-extending and linearly-actuating actuator links <NUM> that act as the drive train for the slave apparatus <NUM>. Actuation of the actuator links <NUM> results in manipulation of the tool shaft <NUM> and thus, the surgical tool <NUM>, and is determined by the control signal received from the master apparatus. The two sets of actuator links <NUM> include a first proximal set 202a and a second distal set 202b having parallel kinematics, thus enabling the two sets 202a, 202b to linearly move in concert (i.e., synchronously) to manipulate the tool shaft <NUM> and thus, the surgical tool <NUM>, in response to control signals from the master apparatus <NUM>. Utilization of a parallel and closed loop kinematic chain for the two sets 202a, 202b of actuator links <NUM> enables decreased structural weight and increased precision, stability, link rigidity, and acceleration, as compared to a single articulating arm equipped with serial kinematics. The parallel kinematic design of the slave apparatus <NUM> further enables differential drive of the two sets 202a, 202b of actuator links <NUM>, thus providing greater maneuverability of the tool shaft <NUM> and surgical tool <NUM> while facilitating the averaging of joint error in the parallel link structure.

Each set 202a, 202b of actuator links <NUM> may be coupled to the tool shaft <NUM> at distal ends <NUM> of the actuator links <NUM> by a coupling ring <NUM> such that the actuator links <NUM> of each set 202a, 202b are attached to the tool shaft <NUM> on a single plane X<NUM> or X<NUM>. The planes X<NUM> and X<NUM> are located at a proximal end <NUM> and a distal end <NUM> of the tool shaft <NUM>, respectively. Accordingly, the embodiment of <FIG> may be described as a dual parallel tripod slave apparatus <NUM>, having two sets 202a, 202b of three actuator links <NUM> (e.g., "three plus three") extending radially outward from the tool shaft <NUM> at two different horizontal planes, thus forming two tripods of actuator links <NUM>. The actuator links <NUM> may be radially spaced apart from adjacent actuator links <NUM> of the same set <NUM> by an angle of about <NUM>° relative to the tool shaft <NUM>.

Note that although three actuator links <NUM> are depicted in each set 202a, 202b in <FIG>, it is further contemplated that a set may include other quantities of actuator links <NUM>. For example, one or each of sets 202a, 202b may comprise four or more actuator links <NUM>. In examples where a set includes more than three actuator links <NUM>, a radial spacing between each actuator link <NUM> may be less than about <NUM>°. Furthermore, although the actuator links <NUM> are described above as being coupled to the coupling rings <NUM>, the actuator links <NUM> may be directly coupled to the tool shaft <NUM> or the surgical tool <NUM> via spherical joints without the utilization of a coupling ring.

In certain embodiments, proximal ends <NUM> of the actuator links <NUM> attach to a support frame <NUM> disposed radially outward of the tool shaft <NUM> and/or surgical tool <NUM>. The proximal ends <NUM> couple to the support frame at attachment points located on different horizontal planes from the attachment points of the distal ends <NUM> with the coupling rings <NUM> or tool shaft <NUM> and/or surgical tool <NUM>. Accordingly, the actuator links <NUM> may be described as being vertically angled (e.g., non-parallel with horizontal planes X<NUM> and X<NUM> or vertical axis Y of the slave apparatus <NUM>). The support frame <NUM> may include any suitable structure to support the quantity of actuator links <NUM> utilized for the slave apparatus <NUM>. In the embodiment of <FIG>, the support frame <NUM> includes two ring-like bases <NUM> and three support columns <NUM> extending therebetween, which may be parallel to the vertical axis Y of the slave apparatus <NUM>. Note that although two bases <NUM> and three support columns <NUM> are described, the slave apparatus <NUM> may include more or less bases and columns having any desired morphologies. The support columns <NUM> and/or bases <NUM> act as anchoring points for the actuator links <NUM>, which may be coupled to the support columns <NUM> and/or bases <NUM> by any suitable type of spherical joints <NUM> enabling at least <NUM>-DOF rotational movement. For example, the spherical joints <NUM> may have a ball-and-socket design, similar to that of the human hip joint, allowing free rotation of the actuator links <NUM> in two planes, while also preventing translation in any direction. In another example, the spherical joints <NUM> are gimbal-type spherical joints.

Similarly, the distal ends <NUM> of the actuator links <NUM> may also be coupled to the coupling rings <NUM>, tool shaft <NUM>, or surgical tool <NUM> by a spherical joint <NUM>. The utilization of two spherical joints <NUM>, <NUM> at opposing ends of the actuator links <NUM> enables movement of the surgical tool <NUM> in all three planes. Thus, the actuator links <NUM> may provide x, y, and z transitional movement as well as pitch and yaw rotational movement for the surgical tool <NUM>, enabling up to <NUM>-DOF of mobility for the surgical tool <NUM> (and up to <NUM>-DOF when utilized with a rotary actuator coupled to the surgical tool <NUM>, described below).

In some embodiments, the slave apparatus <NUM> further includes a rotary actuator to provide <NUM>° rotational movement of the tool shaft <NUM> and/or the surgical tool <NUM>, thus enabling redundant <NUM>-DOF tool roll of the surgical tool <NUM>. In certain embodiments, the rotary actuator is coupled to or disposed within one of the one or more coupling rings <NUM> or the tool shaft <NUM>, and thus may directly rotate the surgical tool <NUM>. In other embodiments, the rotary actuator is coupled to the ring-like bases <NUM>, enabling rotation of the support columns <NUM> and ultimately, the surgical tool <NUM>. The rotary actuator may include any suitable type of rotary mechanism, including a zero-backlash piston driven rack and pinion, a single or dual rotary vane actuator, and the like. In some embodiments, the slave apparatus <NUM> also optionally includes a torque transducer or torque sensor coupled to or disposed within the coupling rings <NUM> and/or the tool shaft <NUM> for torque feedback.

The actuator links <NUM> of the slave apparatus <NUM> utilize a direct drive system with commutated linear motors <NUM> having electromagnetic brakes to manipulate the surgical tool <NUM>. Utilization of commutated linear motors over more conventional motors may eliminate mechanical components that can introduce backlash or compliance and degrade positioning accuracy and repeatability, while also reducing load inertia and enabling more dynamic moves with less overshoot and oscillation. Further, commutated slotless linear motors facilitate smooth force control and high fidelity force feedback by enabling passive backdriving.

In certain embodiments, the motors <NUM> include <NUM>-phase slotless brushless moving magnet linear motors with digital sine wave commutation and optional air bearings. For example, in certain embodiments, the motors <NUM> include slotless brushless direct current (DC) (BLDC) linear motors. In such embodiments, the motors <NUM> may utilize a neodymium iron boron (NdFeB) magnet as a permanent magnet. Each motor <NUM> may be used in combination with a relative linear encoder (e.g., an optical or holographic linear encoder) for both commutation and control, and/or absolute linear encoders to remove the need for homing. The utilization of slotless brushless moving magnet linear motors provides several advantages over other types of motors (e.g., slotted motors), such as extremely small cogging torque (e.g., torque ripple). Thus, slotless brushless moving magnet linear motors enable more accurate driving with reduced vibration and noise during use thereof. Furthermore, the utilization of air bearings facilitates frictionless high-precision positioning with smooth, controlled velocity and high guiding accuracy. Together with the actuator links <NUM>, the motors <NUM> form a direct drive system that enables the robotic surgical system <NUM> to better perform force control, since geared and hydraulic drive systems may suffer from the effects of static and dynamic friction and/or backlash.

Note that, in certain embodiments, slotless brushless moving magnet linear motors, substantially similar to those of the slave apparatus <NUM>, may also be utilized for the master apparatus <NUM>. Furthermore, the rotary actuator of the slave apparatus <NUM> may include a slotless BLDC-type moving magnet (NdFeB) motor to drive tool roll axis for the surgical tool <NUM>.

As described above, the slave apparatus <NUM> is configured to indirectly mount to the head of a patient <NUM>. Thus, in order to alleviate pressure on the patient's head created by the weight of the slave apparatus <NUM> and, in particular, the drive motors <NUM>, one or more components of the slave apparatus <NUM> may be formed of lightweight high modulus/density ratio materials. For example, in certain embodiments, the bases <NUM>, support columns <NUM>, coupling rings <NUM>, and/or tool shaft <NUM> are formed of fiber reinforced engineering plastics, aluminum, Kevlar, carbon fiber, or the like in order to reduce weight applied to the patient's head by the robotic surgical system <NUM>. In addition to utilizing lightweight materials for the slave apparatus <NUM>, a counterbalancing support arm, such as articulating arm <NUM>, may be utilized to support the slave apparatus <NUM>, described in more detail below.

<FIG> illustrates a schematic top-down view of the dual tripod slave apparatus <NUM> of <FIG>. The slave apparatus <NUM> includes two sets 202a, 202b of three actuator links <NUM>, wherein each actuator link <NUM> is radially spaced apart from an adjacent actuator link <NUM> of the same set by an angle of about <NUM>°. Furthermore, each actuator link <NUM> is horizontally or radially aligned (e.g., disposed directly above or below along the axis Y when in a neutral position) with an actuator link <NUM> of an adjacent set <NUM> disposed above or below in relation thereto. Thus, only one set 202a of actuator links <NUM> is visible in the foreground of <FIG>, and only three support columns <NUM> are utilized for anchoring the actuator links <NUM> to the support frame <NUM>. Accordingly, the arrangement of the actuator links <NUM> depicted in <FIG> and <FIG> may be described as "aligned".

<FIG> illustrates a schematic top-down view of the dual tripod slave apparatus <NUM> wherein the actuator links <NUM> are horizontally or radially offset (e.g., unaligned along the axis Y) between adjacent sets <NUM>. As shown, the slave apparatus <NUM> still maintains a dual tripod structure having two sets 202a, 202b of three actuator links <NUM> radially spaced apart at an angle of about <NUM>°. However, unlike the embodiments of <FIG> and <FIG>, each actuator link <NUM> is unaligned with the actuator link <NUM> of the adjacent set <NUM> disposed above or below in relation thereto. Thus, both sets 202a, 202b of actuator links <NUM> are visible in <FIG> (one set 202b is depicted in phantom), and six support columns <NUM> are utilized to support both sets <NUM> of actuator links <NUM>. The utilization of this horizontally or radially offset arrangement of the actuator links <NUM> may enable a different degree of mobility (e.g., range of articulation) for the surgical tool <NUM> as compared to the aligned structure described above, and thus, may be preferred in some instances.

<FIG> illustrates a perspective view of an alternative slave apparatus <NUM> of the robotic surgical system <NUM>, according to certain embodiments. As depicted in <FIG>, the relationships of the vertical positions of the distal ends <NUM> and the proximal ends <NUM> of the actuator links <NUM> (e.g., the vertical orientations or angles of the actuator links <NUM>) between each set 202a, 202b are inverted. That is, in one set 202a, the distal ends 212a of the actuator links 203a are coupled to the tool shaft <NUM> or surgical tool <NUM> at the coupling ring 204a, which is disposed at a position along a length of the tool shaft <NUM> or surgical tool <NUM> located above the coupling point of the proximal ends 214a with the support columns <NUM> in relation to the vertical axis Y. Conversely, the distal ends 212b of the actuator links 203b in set 202b are coupled to the tool shaft <NUM> or surgical tool <NUM> at the coupling ring 204b disposed at a position located below the coupling point of the proximal ends 214b with the support columns <NUM> in relation to the vertical axis Y. This alternative embodiment differs from those described with reference to <FIG>, wherein both sets of actuator links 202a, 202b have substantially similar vertical orientations and/or angles.

<FIG> illustrates a perspective view of yet another alternative slave apparatus <NUM> of the robotic surgical system <NUM> according to certain embodiments. Similar to the slave apparatus <NUM> and <NUM>, the slave apparatus <NUM> includes two sets 202a, 202b of three actuator links <NUM>, each indirectly coupled to the tool shaft <NUM> or the surgical tool <NUM> near the distal ends <NUM> thereof. However, unlike the embodiments described above, the two sets 202a, 202b of actuator links <NUM> are further coupled directly or indirectly to a single actuation platform <NUM> at the proximal ends <NUM> thereof such that the proximal ends <NUM> are aligned along a single vertical plane Y<NUM>. The actuation platform <NUM> acts in a manner similar to the support columns <NUM> and provides mounting support for the actuator links <NUM>. In certain embodiments, the actuation platform <NUM> includes a rotational joint <NUM> (e.g., a hinge enabling horizontal and/or vertical rotation) on a backside thereof for rotatable coupling with an extension of the forehead support <NUM>, described in greater detail with reference to <FIG> and <FIG>.

In certain embodiments, the distal ends <NUM> of the actuator links <NUM> in each set 202a, 202b are connected to the coupling rings <NUM> and/or tool shaft <NUM> and/or surgical tool <NUM> via an intermediary platform <NUM> upon which the distal ends in each set 302a, 302b converge. The intermediary platforms <NUM> enable the translation of linear movement from actuator links <NUM> into corresponding transitional and rotational manipulation of the surgical tool <NUM>. Accordingly, both sets 202a, 202b of actuator links <NUM> may act in concert to provide x, y, and z transitional movement, as well as pitch and yaw rotational movement. In combination with the utilization of a rotary actuator that may be coupled to the coupling rings <NUM> and/or tool shaft <NUM>, the actuator links <NUM> enable up to <NUM>-DOF of the tool shaft <NUM> and/or tool <NUM>. Note that although the intermediary platforms <NUM> are depicted as having a conical shape, the intermediary platforms <NUM> may have any suitable morphology to enable translation of the linear movement of the actuator links <NUM> into up to <NUM>-DOF movement of the surgical tool <NUM>.

Although the structures depicted in <FIG>, <FIG>, and <FIG> are described with reference to the slave apparatus <NUM>, the same or substantially the same structures and arrangements may be utilized for the master apparatus <NUM>. For example, when utilizing the dual tripod slave apparatus <NUM>, the master apparatus <NUM> may mimic the slave apparatus <NUM> and share the same dual tripod structure, though scaled up for easier manipulation by the operator <NUM>. Accordingly, the master apparatus <NUM> may include a master surgical tool handle replicating the surgical tool <NUM> and coupled to two sets of three radially extending master actuator links, wherein each set of the master actuator links is coupled to the master surgical tool handle along a single horizontal plane to form a dual tripod structure. Further, the master apparatus <NUM> may include slotless BLDC-type master motors, which facilitate torque feedback when used in combination with torque sensors.

By mimicking the mechanical structure of the slave apparatus <NUM> for the master apparatus <NUM>, complete general spatial motion of the slave apparatus <NUM> and thus, the surgical tool <NUM>, is enabled. Furthermore, mimicking of the mechanical structure of the slave apparatus <NUM> for the master apparatus <NUM> may improve ease of use for the operator <NUM>, as the positions for the slave apparatus <NUM> and the master apparatus <NUM> may be made identical but for structure scaling. A dual tripod structure for the master apparatus <NUM> also enables the operator <NUM> to perform surgical procedures with the robotic surgical system <NUM> utilizing only one hand and thus, the operator <NUM> may simultaneously use his or her other hand for other actions such as for positioning of an endoilluminator or a second tool. In some embodiments, a pair of robotic surgical systems <NUM> may be utilized in combination to perform two-handed surgery by the operator <NUM>, each hand of the operator <NUM> controlling an individual robotic surgical system <NUM> and thus, an individual slave apparatus <NUM>.

<FIG> and <FIG> illustrate perspective views of the slave apparatus <NUM> when mounted to the head of the patient <NUM>, according to certain embodiments. Accordingly, <FIG> and <FIG> are herein described together for clarity. As shown, the slave apparatus <NUM> is coupled to the slave apparatus support system <NUM>. In certain aspects, the slave apparatus support system <NUM> aids in supporting the slave apparatus <NUM> in an upright and secured (e.g., fixed) position over the patient's eye <NUM>, which is held open by a speculum <NUM>, to prevent relative movement between the patient's head and the slave apparatus <NUM>. For example, when the slave apparatus <NUM> is attached to the slave apparatus support system <NUM> and mounted on the patient's head, the slave apparatus <NUM> will move with the patient's head, thereby eliminating, or at least reducing, the need for general anesthesia and neuromuscular blockade. Anesthesia and neuromuscular blockades are typically used to prevent patient movement during surgical procedures, which can disrupt utilization of the surgical tool <NUM> and/or lead to surgical instrument-induced damage of the patient's eye. Thus, the risks associated with involuntary movement of the patient may be greatly reduced or eliminated by utilizing the slave apparatus <NUM> and slave apparatus support system <NUM>. In certain aspects, the slave apparatus support system <NUM> further reduces or eliminates any pressure against the patient's head caused by the weight of the slave apparatus <NUM> by employing a counterbalancing mechanism. Accordingly, the patient <NUM> will not feel the weight of the slave apparatus <NUM>, but may still feel the inertia, which will slow down and discourage patient movement.

The slave apparatus support system <NUM> generally includes the forehead support <NUM>, articulating arm <NUM>, and base <NUM>. The forehead support <NUM> is a sterilizable or disposable U-shaped support configured to contact and rest on the patient's forehead and temples. In order to improve comfort for the patent <NUM>, an underside or patient-facing side of the forehead support <NUM> includes a surface padded with, for example, a viscoelastic material, such as dense memory foam. In certain embodiments, the forehead support <NUM> is secured to the patient's head utilizing a broad and adjustable head strap <NUM>, which may be fastened via any suitable fastening mechanism. In certain embodiments, the head strap <NUM> is adjustably fastened via a hook and loop fastener such as, for example, Velcro®, to enable a customized fit with respect to the patient. By attaching the slave apparatus <NUM> to the patient's head via the forehead support <NUM>, patient head rotation relative to the slave apparatus <NUM> is virtually eliminated.

The slave apparatus <NUM> is attached to the forehead support <NUM> via an adjustable attachment <NUM> to accommodate different patient anatomical characteristics (e.g., head geometries) and enable lateral positioning of the slave apparatus <NUM> over the desired patient's eye <NUM>. In certain embodiments, the attachment <NUM> includes an articulating arm, such as a single serial articulating arm or two parallel articulating arms, medially attached to the forehead support <NUM> to facilitate positioning of the slave apparatus <NUM> over either of the patient's eyes. In the embodiment of <FIG> and <FIG>, the attachment <NUM> is shown as having two parallel articulating arms <NUM> with two linkages each, and five revolute joints <NUM>, which the linkages rotate about laterally. In certain embodiments, the attachment <NUM> further includes a distal revolute joint <NUM> at a distal end thereof to enable rotation of the slave apparatus <NUM> about a horizontal axis.

In order to support the weight of the slave apparatus <NUM>, the forehead support <NUM> is further coupled to the counterbalancing and passive articulating arm <NUM> supported by the base <NUM>. In certain embodiments, the articulating arm <NUM> includes a SCARA mechanism <NUM> to allow passive, lockable horizontal movement of the forehead support <NUM> and the slave apparatus <NUM> attached thereto, as well as a four-bar parallelogram mechanism <NUM> to enable passive, lockable vertical movement thereof. For example, as shown in <FIG> and <FIG>, the SCARA mechanism <NUM> is formed by at least two links <NUM> and at least three revolute joints <NUM> having vertical axes to create passive motion parallel to a floor plane of the operating room. The four-bar parallelogram mechanism <NUM> is formed by four bars <NUM> and four revolute joints <NUM> having horizontal axes to create passive vertical motion perpendicular to the floor plane. The four-bar parallelogram mechanism <NUM> is further counterbalanced by a spring <NUM>, such as an air spring, constant force spring, or the like, which enables locking of the four-bar parallelogram mechanism <NUM>. Together, the SCARA mechanism <NUM> and the four-bar parallelogram mechanism <NUM> provide an adjustable counterbalancing mechanism to account for the weight of the slave apparatus <NUM>, which is mounted to and moves with the patient's head during a surgical procedure for increased patient safety in the context of patient head movement. Note that although the passive articulating arm <NUM> is shown as having the SCARA mechanism <NUM> at a distal end thereof and the four-bar parallelogram mechanism <NUM> at a proximal end thereof, the passive articulating arm <NUM> may include the two mechanisms in any order or arrangement as desired.

<FIG> illustrates a block diagram of a signal flow of the robotic surgical system <NUM>. As described above, the robotic surgical system <NUM> employs a master-slave type system that includes the master apparatus <NUM> and the slave apparatus <NUM>, which may have substantially similar architectures or arrangements with one another. When the operator <NUM> operates the master apparatus <NUM>, the master apparatus <NUM> generates a control signal that is transmitted between the master apparatus <NUM>, the computer <NUM>, and the slave apparatus <NUM>. Receiving the control signal, the slave apparatus <NUM> controls the operation of a surgical tool <NUM>.

The master apparatus <NUM> includes a plurality of master encoders <NUM> and master force sensors <NUM> communicatively coupled therewith and configured to provide <NUM>-DOF force and tactile feedback to the operator <NUM> during use. In certain embodiments, the master encoders <NUM> include a rotary encoder communicatively coupled to a master surgical tool handle to sense angular position and/or a torque sensor to sense static and/or dynamic torque applied thereto. In embodiments wherein the master apparatus <NUM> includes a dual tripod architecture similar to the slave apparatus <NUM>, each master actuator link may be in communication with one or more master encoders <NUM> and/or one or more master force sensors <NUM>. For example, each master actuator link may correspond to one master encoder <NUM> and one master force sensor <NUM>. However, any suitable number of master encoders <NUM> and master force sensors <NUM> may be utilized depending on the structure of the master apparatus <NUM>. In certain embodiments, the number of the master actuator links, master encoders <NUM>, and master force sensors <NUM> depends upon the number of actuator links <NUM> of the slave apparatus <NUM>. For example, the master apparatus <NUM> may comprise at least one master actuator link, master encoder <NUM>, and master force sensor <NUM> per actuator link <NUM> of the slave apparatus <NUM>, such as six master actuator links, six master encoders <NUM>, and six master force sensors <NUM> when the slave apparatus <NUM> comprises six actuator links <NUM>. In another example, the master apparatus <NUM> includes an additional seventh master encoder <NUM> and seventh master force sensor <NUM> in communication with the master surgical tool handle.

In certain embodiments, the master encoders <NUM> include fiber-optic-coupled sine-cosine (i.e., sine) encoders providing position and direction values of the master as analog sine waves. In certain embodiments, the master encoders <NUM> include linear optical encoders, such as linear optical absolute encoders and linear optical incremental encoders. In certain embodiments, the master force sensors <NUM> include strain gauges.

As the operator <NUM> manipulates the master apparatus <NUM>, the movement thereof drives a plurality of master motors <NUM> (e.g., slotless BLDC-type motors), causing one or more of the master encoders <NUM> to read different positions (KP1) of one or more master actuator links. Simultaneously, one or more master force sensors <NUM> sense the movement of the master actuator links as they impart forces (KF1) on the structure of the master apparatus <NUM>. The master force sensors <NUM> and the master encoders <NUM> act to send a plurality of values (e.g., signals) <NUM> corresponding with the KP1 and a plurality of values <NUM> corresponding with the KF1 to the computer <NUM>, which then reads the values <NUM>, <NUM> and applies various filtering <NUM> and scaling <NUM> (e.g., gain, reduction, compensation, adjustment) to the values. Thereafter, the computer <NUM> sends an updated control signal comprising filtered and scaled values <NUM>', <NUM>' to the slave apparatus <NUM> via a slave drive train controller <NUM>. The signals instruct the motors <NUM> to linearly actuate the actuator links <NUM> and/or rotate the rotary actuator coupled directly or indirectly to the surgical tool <NUM> and/or the tool shaft <NUM>. Accordingly, the slave apparatus <NUM> is manipulated in a desired movement or to a desired position to perform surgical maneuvers with the surgical tool <NUM> on the patient <NUM>.

The slave apparatus <NUM> optionally has a set of slave encoders <NUM> and slave force sensors <NUM>. For example, the slave apparatus <NUM> includes a set of six or seven slave encoders <NUM> and six or seven slave force sensors <NUM>, each slave encoder <NUM> and/or slave force sensor <NUM> corresponding with a single actuator link <NUM> and/or the surgical tool <NUM>. In certain embodiments, the slave encoders <NUM> are substantially similar to the master encoders <NUM>, and may include fiber-optic-coupled sine-cosine (i.e., sine) encoders and/or linear optical encoders. Similarly, the slave force sensors <NUM> may be substantially similar to the master force sensors <NUM> and include strain gauges. In certain examples, the slave apparatus <NUM> include strain gauges <NUM> coupled to the surgical tool <NUM> and/or the actuator links <NUM> that are configured to sense contact forces at the <NUM>-<NUM> (Hertz) domain, otherwise known as the fidelity channel. In certain embodiments, the slave apparatus <NUM> optionally includes a torque transducer or torque sensor configured to sense static and/or dynamic torque applied to the surgical tool <NUM>. In further embodiments, the slave apparatus <NUM> includes a single force-sensing device configured to provide <NUM>-DOF force feedback for the entire slave apparatus <NUM>.

As the slave apparatus <NUM> is commanded to manipulate the surgical tool <NUM>, the slave encoders <NUM> read different positions (KP2) of the actuator links <NUM> and the slave force sensors <NUM> simultaneously sense contact and torque forces (KF2) against the surgical tool <NUM>. A plurality of values <NUM> corresponding with the KP2 and a plurality of values <NUM> corresponding with the KF2 are then sent back to the computer <NUM>, which applies filtering <NUM> and scaling <NUM> and translates the updated control signal comprising filtered and scaled values <NUM>', <NUM>' to the master apparatus <NUM> via a master drive train controller <NUM>. Generally, the values <NUM>, <NUM> are up-scaled by the computer <NUM> for translation to the master apparatus <NUM>, while the values <NUM>, <NUM> are downscaled for translation to the slave apparatus <NUM>. In certain embodiments, the values <NUM>, <NUM> and <NUM>, <NUM> are scaled according to fixed scaling factors. In other embodiments, the values <NUM>, <NUM> and <NUM>, <NUM> are scaled according to dynamic scaling factors.

The master motors for the master apparatus <NUM> are then driven by the scaled signals and the operator <NUM> can sense contact with different types of surfaces and/or tissues during ophthalmic surgery, such as vitreoretinal surgery. In addition to translating signals between the master apparatus <NUM> and the slave apparatus <NUM>, the computer <NUM> coordinates the actuator links of each of the master apparatus <NUM> and the slave apparatus <NUM>. Kinematic and dynamic models are loaded into the computer <NUM> to stabilize the system and provide coordinated <NUM>-DOF or <NUM>-DOF motion to the slave apparatus <NUM> coupled to the surgical tool <NUM>. In certain embodiments, the robotic surgical system <NUM> includes one or more electromagnetic brakes for each robot axis. For example, braking of the robotic surgical system <NUM> may be controlled in part by watchdog timers, a power failure sensor, and/or differences determined by the computer <NUM> between control signals (i.e., commanded position and pose, upon filtering <NUM> and scaling <NUM>) versus encoder-sensed actual position and pose.

The execution of filtering <NUM> and scaling <NUM> of values by the computer <NUM> during transmission of values between the slave apparatus <NUM> and the master apparatus <NUM> provides numerous benefits during operation of the robotic surgical system <NUM>. Accordingly, many of the disadvantages that may be associated with manual surgery, as well as conventional robotic surgical systems, may also be averted. For example, involuntary operator movement or operator tremor (i.e., physiological tremor), which is very common with inexperienced or low volume surgeons as well as some older surgeons, may be filtered by a tremor filter of the computer <NUM>. Physiological tremor leads to an intolerable imprecision of surgical procedures that require a positioning accuracy of about <NUM> (micrometers) and below. Typically, physiological hand tremor lies in the band of <NUM>-<NUM> with an amplitude of <NUM> and can be approximated by a sinusoidal movement, whereas controlled hand movement of a surgeon during microsurgeries (e.g., vitreoretinal surgery) is usually less than <NUM>. For effective tremor filtering, the robotic surgical system <NUM> may utilize one or more adaptive algorithms loaded into the computer <NUM> to create zero-phase lag in the filtering process to filter tremor from the master output in real-time. In certain embodiments, filtering <NUM> is executed by a zero-phase delay low-pass filter (LPF) with a cut-off frequency of <NUM>. For example, the filter may be a first-order Butterworth LPF.

As described above, the computer <NUM> is further configured to execute force downscaling, force limiting, position scaling, and velocity scaling between the master apparatus <NUM> and the surgical tool <NUM> during the scaling operations <NUM>. Force downscaling, force limiting, and position and velocity scaling may together be described as the user interface control law embedded within the robotic surgical system <NUM>. As illustrated in <FIG>, the robotic surgical system <NUM> may utilize a closed control loop to control force and positioning of the slave apparatus <NUM>. The closed control loop may further be utilized to provide haptic feedback to the operator <NUM> during use thereof. For example, the master force sensors <NUM> may sense operator forces upon the master apparatus <NUM>, which may then be converted into downscaled control signals provided to the slave apparatus <NUM>. The sensed force values may be scaled by utilizing a software and user interface controllable scaling ratio or a fixed or predetermined scaling ratio loaded into the computer <NUM>. In some examples, the computer <NUM> may be configured to execute cooperative control algorithms to generate movement of the slave apparatus <NUM> based on a scaled difference between tool-tissue and operator forces.

In addition to force control, the robotic surgical system <NUM> provides force or tactile (e.g., haptic) feedback between the surgical tool <NUM> and the master apparatus <NUM>. In certain embodiments, the robotic surgical system <NUM> includes a haptic feedback system (e.g., feedback loop) separate from the closed control loop described above. In other embodiments, the haptic feedback loop is integrated with the force and positioning control loop. Generally, the haptic feedback loop collects and transmits tactile information between the surgical tool <NUM> and the master apparatus <NUM> in a domain of between about <NUM> and up to about <NUM> in order to enable the operator <NUM> to distinguish biomechanical properties of tissues during surgery.

In summary, embodiments of the present disclosure include devices and systems for improving the accuracy and dexterity of ophthalmic surgical operations while minimizing trauma to the patient. Voluntary and involuntary patient movement during surgical procedures, and in particular, delicate and precise procedures such as vitreoretinal surgery, may typically cause undesired and accidental contact between surgical tools and ocular tissues. Such contact may lead to serious complications to the patient's eye, which can develop into potentially irreversible damage and visual impairment. The devices and systems described herein include embodiments wherein a surgeon may mount and secure a surgical slave apparatus to the head of a patient such that the slave apparatus moves along with the head of a patient during use thereof. By utilizing the devices and systems described herein, many of the risks associated with patient movement during ophthalmic surgical procedures may be reduced or eliminated. Accordingly, the described embodiments also eliminate, or at least reduce, the need for the provision of general anesthetics with neuromuscular blockade, which are utilized in part to prevent patient movement.

Still further, the devices and systems described herein may mitigate some of the inherent restrictions on vitreoretinal surgery related to human sensory and motor limitations. For example, surgeon fatigue, hand tremor, and the inability to perceive miniscule tactile differences between tissues in the ocular space are common limitations on the accuracy and effectiveness of vitreoretinal procedures. By providing mechanisms for force control (e.g., scaling and filtering) and feedback (e.g., tactile feedback) while maintaining <NUM>-DOF movement, the devices and systems described herein provide surgeons with increased dexterity and precision wherein the surgeon has an improved physical connection with the surgical site. Thus, the devices and systems described herein may decrease the risk of surgical error and reduce operative times, thereby increasing the overall effectiveness of vitreoretinal procedures.

Although vitreous surgery is discussed as an example of a surgical procedure that may benefit from the described embodiments, the advantages of the surgical devices and systems described herein may benefit other surgical procedures as well.

Claim 1:
A surgical system (<NUM>) for manipulating a surgical tool, comprising:
a master apparatus (<NUM>);
a slave apparatus (<NUM>) controllably coupled to the master apparatus and configured to be mounted to a patient's head, the slave apparatus comprising:
a support frame (<NUM>);
a first set (202a) of three or more linearly-actuating links (<NUM>) coupled to the support frame (<NUM>) in a radial manner, each link (<NUM>) of the first set radially spaced apart from an adjacent link in the first set by an angle less than or equal to about <NUM> degrees;
a second set (202b) of three or more linearly-actuating links (<NUM>) coupled to the support frame (<NUM>) in a radial manner, each link of the second set radially spaced apart from an adjacent link in the second set by an angle less than or equal to about <NUM> degrees;
a surgical tool (<NUM>) coupled to the first and second sets of links, the first and second sets of links providing translational and rotational movement to the surgical tool; and
one or more direct drive actuators (<NUM>) coupled to each link (<NUM>) of the first and second sets of links (202a, 202b), the direct drive actuators configured to provide linear movement to each link;
wherein the slave apparatus (<NUM>) is further coupled to a slave apparatus support (<NUM>) system comprising:
a u-shaped forehead pad (<NUM>);
an adjustable head strap (<NUM>) attached to the forehead pad; and
at least one adjustable arm (<NUM>) extending from the forehead pad and configured to support the slave apparatus (<NUM>) over an eye of a patient.