MECHANISM AND METHOD WITH VARIABLE COUNTERBALANCE FOR CONTROLLING MOVEMENT AND FORCE OF A HEAD OF A MEDICAL SYSTEM AT AN ANATOMICAL SITE - Patent application

Abstract

The medical system includes a head having an end positioned facing a reference surface and a multi-stage sliding mechanism coupled to the head. The multi-stage sliding mechanism includes a coarse float mechanism configured to allow movement of the head relative to the reference surface and a fine float mechanism configured to limit a force applied through the head to an initial force and to reduce the force applied through the head to a reduced force less than the initial force in response to the presence of a first trigger event. The first trigger event can correspond to effective engagement between a cone attachment portion of the head and a patient interface coupled to an anatomical location on the reference surface.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of medical systems having a system head, and more particularly to mechanisms and methods for enabling and controlling movement of the system head relative to an anatomical site, including varying the counterbalance to control the force of the head at the anatomical site. [Background technology]

[0002] As part of a medical procedure, the head of the medical system may be manually positioned relative to an anatomical site for the purpose of performing a diagnostic procedure, an imaging procedure, a surgical procedure, or a combination of two or more of these procedures. For example, in ophthalmic surgery, a patient may be supine on a surgical table with the eye facing the surgical head of the ophthalmic surgical system, and a surgeon may manipulate the surgical head laterally and up and down relative to the eye to couple the surgical head to the eye. In some cases, a patient interface is connected and secured to the eye, and a cone attachment of the surgical head is connected to the patient interface. The patient interface is positioned between the eye and the surgical head to immobilize the eye relative to the ophthalmic surgical system.

[0003] Manipulation of the surgical head relative to the eye, particularly downward movement of the head toward the eye, can result in contact between the head and the eye that can create unacceptable forces on the eye that can lead to injury. It is therefore desirable to have a surgical system with mechanisms to protect against these unacceptable forces. Summary of the Invention

[0004] The present disclosure relates to a method for coupling a head of a medical system to an anatomical site, the method including moving the head relative to the anatomical site and limiting a force applied by the head to the anatomical site to an initial force. In response to the presence of a first trigger event, the method further includes reducing the force applied by the head to the anatomical site to a reduced force less than the initial force. The first trigger event may correspond to effective coupling between a cone mount of the head and a patient interface coupled to the anatomical site of a reference plane.

[0005] The present disclosure also relates to a medical system including a head having an end positioned facing a reference surface and a multi-stage sliding mechanism coupled to the head. The multi-stage sliding mechanism includes a coarse float mechanism configured to allow movement of the head relative to the reference surface and a fine float mechanism configured to limit a force applied through the head to an initial force and to reduce the force applied through the head to a reduced force less than the initial force in response to the presence of a first trigger event. The first trigger event may correspond to effective engagement between a cone attachment portion of the head and a patient interface coupled to an anatomical location on the reference surface.

[0006] The present disclosure also relates to a control system for controlling a fine float counterbalance mechanism of a medical system having a head, a cone attachment mechanism configured to secure the head to a patient interface, and an eye attachment mechanism configured to secure the patient interface to an anatomical location. The fine float counterbalance mechanism is configured to set the apparent weight of a load mass including the head to either heavy or light. The control system includes a set of sensors, a set of operator controls configured to provide a control signal indicative of brake release, and a controller coupled to the set of sensors and the set of operator controls. The controller includes a variable force module configured to set the apparent weight of the load mass to either heavy or light based on sensor signals from the sensors and signals from the operator controls. The set of sensors includes a displacement sensor configured to provide a sensor signal indicative of movement of the head through the fine float mechanism, a cone-attached sensor configured to provide a sensor signal indicative of coupling between the head and the patient interface, and an eye-attached sensor configured to provide a sensor signal indicative of coupling between the patient interface and the anatomical location.

[0007] It will be understood that other aspects of the apparatus and method will become apparent to those skilled in the art from the following detailed description, in which various aspects of the apparatus and method are shown and described by way of illustration. As will be understood, these aspects may be implemented in other different forms, and their several details may be modified in various other aspects. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature, and not as restrictive.

[0008] Various aspects of systems, apparatus and methods are now presented in a detailed description, by way of example and not limitation, with reference to the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a block diagram of an ophthalmic surgical system having a focusing objective head, also referred to as a surgical head, that couples to the eye via a patient interface. [Figure 2] FIG. 2 is a detailed block diagram of one embodiment of the ophthalmic surgical system of FIG. 1. [Figure 3A] FIG. 1 is a schematic diagram of a surgical head of an ophthalmic surgical system coupled to a patient interface. [Figure 3B] FIG. 1 is a schematic diagram of a surgical head of an ophthalmic surgical system detached from a patient interface. [Figure 4A] FIG. 1 is a side schematic view of an ophthalmic surgical system having a transmission arm assembly that allows multi-dimensional (e.g., lateral and up-down) movement of a surgical head. [Figure 4B] FIG. 1 is a schematic diagram of a top view of an ophthalmic surgical system having a transfer arm assembly that allows multi-dimensional (e.g., lateral and up-down) movement of the surgical head. [Figure 5A] FIG. 10 is a displacement diagram of a long-distance slide mechanism of a multi-stage transmission mechanism of a transmission arm assembly. [Figure 5B] FIG. 10 is a displacement diagram of a short-distance slide mechanism of a multi-stage transmission mechanism of a transmission arm assembly. [Figure 6] 1 is a flowchart of a method of docking a surgical head of an ophthalmic surgical system to a surgical site, for example, an eye. [Figure 7A-B] 1 is a schematic diagram of one stage of the docking procedure enabled by the transfer arm assembly. [Figure 7C-D] 1A-1C are schematic diagrams of a stage of the docking procedure enabled by the transfer arm assembly. [Figure 7E] 1A-1C are schematic diagrams of a stage of the docking procedure enabled by the transfer arm assembly. [Figure 8A] 7 is a graph showing the change in force on the eye at different times during the docking procedure of FIG. 6. [Figure 8B] 7 is a graph showing the change in force on the eye at different times during the docking procedure of FIG. 6. [Figure 9A]FIG. 1 is a schematic side view of a configuration of a multi-stage transmission mechanism having a pulley-type long-distance slide mechanism and a magnetic-type short-distance slide mechanism. [Figure 9B] FIG. 10 is a top schematic view of a configuration of a multi-stage transmission mechanism having a pulley-type long-distance slide mechanism and a magnetic-type short-distance slide mechanism. [Figure 10A] FIG. 1 is a schematic diagram of a multi-stage transmission mechanism showing components of a magnetic fine float counterbalance mechanism in a first state. [Figure 10B] FIG. 10 is a schematic diagram of a multi-stage transmission mechanism showing components of the magnetic fine float counterbalance mechanism in a second state. [Figure 11] FIG. 1 is a block diagram of a control system for an ophthalmic surgical system. [Figure 12A-C] 1A-1C are schematic diagrams of a mechanical one-way brake of an ophthalmic surgical system illustrating different stages of the docking procedure. [Figure 13] 1 is a flowchart of a method for moving the head of a medical system relative to an anatomical site. [Figure 14] 1 is a flowchart of a method of coupling a head of a medical system to an anatomical site. [Figure 15] 1 is a flowchart of a method of coupling a head of a medical system to an anatomical site. DETAILED DESCRIPTION OF THE INVENTION

[0010] Disclosed herein is a medical system having a mechanism for enabling and controlling movement of a head relative to an anatomical site. The medical system may be a diagnostic system configured to perform a diagnostic procedure at a diagnostic site, an imaging system configured to image an imaging site, a surgical system configured to perform a surgical procedure at a surgical site, or a combination of two or more of these systems. The system includes a transmission arm assembly having a head and a multi-stage sliding mechanism coupled to the head. The multi-stage sliding mechanism includes a long-distance sliding mechanism (or coarse-float mechanism) and a short-distance sliding mechanism (or fine-float mechanism). The long-distance sliding mechanism is configured to move the head in a direction toward a reference plane. The reference plane may correspond, for example, to a bed on which a patient having the anatomical site can lie during the procedure. The procedure may be a diagnostic procedure, an imaging procedure, a surgical procedure, or a combination of two or more of these procedures.

[0011] To protect against unnecessary force on the anatomical site, the short-distance sliding mechanism is configured to automatically stop movement of the head toward the reference surface in response to a resistance force (our reaction force) to continued movement of the head toward the reference surface by the long-distance sliding mechanism.

[0012] To protect against prolonged application of an initial force to the anatomical site, the short-travel sliding mechanism is further configured to limit the force applied to the site via the head to the initial force and to automatically reduce the force applied to the site via the head to a reduced force less than the initial force in response to the presence of a trigger event, which may be, for example, attachment between the head and a patient interface coupled to the patient's anatomical site, e.g., the eye.

[0013] To further protect against unwanted forces on the anatomical site, the long-travel sliding mechanism is configured to prevent movement of the head toward the reference surface while simultaneously allowing movement of the head away from the reference surface in response to the presence of a first triggering event, which may be, for example, attachment between the head and a patient interface coupled to the patient's anatomical site, such as the eye.

[0014] The medical systems disclosed in detail hereinafter include components and devices that provide imaging, diagnostic, and surgical capabilities. Thus, although the medical systems are referred to as ophthalmic surgical systems, they may also be considered imaging and / or diagnostic systems.

[0015] Ophthalmic Surgery System 1 , an ophthalmic surgical system 1000 for non-invasive surgery includes a control system 100, one or more user interfaces 110, a surgical component 200, one or more imaging / vision components 300, 400, and a target localization device 450. Other components of the integrated surgical system 1000 include a beam conditioner and scanner 500, a beam combiner 600, and a focusing objective head 700 that couples to a patient interface 800.

[0016] The surgical component 200 may be a femtosecond laser source that outputs a laser beam 201. The femtosecond laser provides a highly localized, non-thermal photodisruptive laser-tissue interaction with minimal collateral damage to surrounding ocular tissue. The photodisruptive interaction of the laser is utilized in optically transparent tissue. The primary mechanism of laser energy deposition in ocular tissue is not by absorption, but by a highly nonlinear multiphoton process. This process is only effective at the focus of a pulsed laser with high peak intensity.

[0017] The first imaging / vision component 300 may be an OCT imager that outputs an OCT beam 301. OCT technology provides images that aid in the diagnosis, localization, and guidance of laser surgery directed at different tissue targets within the eye. For example, OCT imaging can be used to determine the structural and geometric condition of the iridocorneal angle and determine the accessibility of ocular tissue for treatment. OCT imaging can provide the spatial resolution, tissue penetration, and contrast necessary to resolve microscopic details of ocular tissue.

[0018] The second imaging / vision component 400 may be a visual observation device that outputs a visual observation beam 401 and an illumination source. The visual observation device 400 provides an image that assists in identifying the surgical location. The visual observation device may include, for example, a video camera or a telescope. The camera may be a digital camera equipped with a goniometer to provide an image of the angle of the eye. The illumination source is positioned for optimal irradiance of the object of interest, e.g., a tissue target within the eye. The illumination source may be an LED or light transmitted via a fiber optic cable.

[0019] Target-localization device 450 may be a dual aiming beam device as disclosed in U.S. Patent Application Publication No. 2021 / 0235986, entitled "System and Method for Locating a Surface of Ocular Tissue for Glaucoma Surgery Based on Dual Aiming Beams," the contents of which are incorporated herein by reference. Dual aiming beam device 450 outputs a pair of light beams, referred to herein as dual aiming beams 451 a / 451 b, for use in detecting the surface of ocular tissue in the surgical field.

[0020] The beam conditioner and scanner 500 is configured to set beam parameters of the light beam, including beam size and divergence. Beam conditioning can also include additional functions, such as setting beam power or pulse energy and shuttering the beam on or off. As shown in FIG. 1 , the laser beam 201 from the femtosecond laser source 200 and the OCT beam 301 from the OCT imager 300 are directed toward the beam conditioner and scanner 500. The beam conditioner and scanner 500 includes components, such as scanning mirrors, for scanning the laser beam 201 and the OCT beam 301 independently of each other. Different types of scanners can be used to scan the laser beam 201 and the OCT beam 301. To scan the light beams 201 and 301 laterally, angular scanning galvanometer scanners are available, for example, from Cambridge Technology, Munich, Germany, and Scanlab, Bedford, MA.

[0021] The beam combiner 600 is configured to split and combine light beams. The beam combiner 500 may include a dichroic or polarizing beam splitter that splits and recombines light beams having different wavelengths and / or polarizations. The beam combiner 600 may also include optics for modifying specific parameters of the individual light beams, such as beam size, beam angle, and divergence. As shown in FIG. 1 , two or more of the laser beam 201, the OCT beam 301, the visual observation beam 401, and the dual-aiming beams 451 a / 451 b may be combined with a dichroic, polarizing, or other type of beam combiner 600 and provided to a focusing objective lens head 700 as a combined light beam 701 to reach a common target volume 720 of ocular tissue in the eye 1.

[0022] The focusing objective head 700 is optically coupled to receive the combined light beam 701 from the beam combiner 600 and direct the received combined light beam into alignment with a common target volume 720 of ocular tissue of the eye 1 .

[0023] The control system 100 is connected to the other components 200, 300, 400, 450, 500, and 700 of the integrated surgical system 1000. The control system 100 may be a single computer or multiple interconnected computers configured to control the hardware and software components of the other components of the ophthalmic surgical system 1000. The user interface 110 of the control system 100 may present a graphical user interface (GUI) that receives instructions from a user and displays information for the user's viewing. Input information and commands from the user include, but are not limited to, system commands, motion control for docking the patient's eye to the system, selection of a pre-programmed or live-generated surgical plan, navigating through menu selections, setting surgical parameters, responding to system messages, determining and accepting the surgical plan, and commands for executing the surgical plan. Output from the system to the user includes, but is not limited to, display of system parameters and messages, display of an image of the eye, graphical, numerical, and textual displays of the surgical plan, and the progress of the surgery.

[0024] Control signals from the control system 100 to the femtosecond laser source 200 function to control the internal and external operating parameters of the laser source, including, for example, power, repetition rate, and beam shutter. Control signals from the control system 100 to the OCT imager 300 function to control OCT beam parameters, as well as the acquisition, analysis, and display of OCT images of the tissues in the surgical field.

[0025] Control signals from the control system 100 to the dual aiming beam device 450 function to control the output of beams of light by one or more aiming beam sources of the dual aiming beam device. Control signals from the control system 100 to the visual observation device 400 function to control the capture, image processing, and display of video images of tissue in the surgical field and spots of light on the tissue surface in the surgical field resulting from one or more beams of light output by the dual aiming beam device 450. To this end, the line of sight of the visual observation device 400 may be aligned with the femtosecond laser and directed into the target area of ​​the eye.

[0026] Control signals from the control system 100 to the beam conditioner and scanner 500 function to control the scanning of the laser beam output by the femtosecond laser source 200 and the OCT beam output by the OCT imager 300. The control signals to the beam conditioner and scanner 500 can include the position, size, and shape of the surgical pattern, expressed in terms of the intended location of the laser's focal point and the position coordinates of the laser's scan path across the surgical volume. These types of control signals can be preprogrammed with one or more operator-selectable control parameters. The control parameters for the surgical pattern can include the pattern position, pattern shape, length, width, and depth, laser spot, line, and layer separation, and laser pulse energy. The control signals between the various subsystems and components are calibrated before operating the surgical system. Calibration includes calibrating the pixel coordinates acquired and displayed by the visual observation device 400 and OCT imager 300 to the actual physical coordinates of the eye, and calibrating the commanded movements of the OCT and laser scanner systems to the actual OCT and laser beam displacements of the eye.

[0027] Control signals from the control system 100 to the focusing objective head 700 can function to control the axial scanning of either or both the laser beam 201 and the OCT beam 301 through the motorized focusing objective.

[0028] Commanding the integrated surgical system 1000 to perform a surgical incision involves docking the system to the eye, acquiring and displaying visual observation images including spots from the dual aiming beams and OCT images on a computer screen, determining coordinate locations and other parameters of the intended surgical incision based on the displayed images, and instructing the control system 100 to execute a surgical pattern based on information gathered from those images. The image-based parameters may be determined by an operator of the integrated surgical system 1000 or may be determined by image processing and analysis computer algorithms. Instructions using these parameters may be provided by the operator when entering input data in the form of text, mouse clicks, and drag-and-drop instructions on a computer screen. Alternatively, a system processor, which may be included in the control system 100, generates instructions for execution by the control system based on previously determined parameters.

[0029] 2, the integrated surgical system may be configured to transmit one or more of a laser beam 201, an OCT beam 301, a visual observation beam 401, and a pair of optical aiming beams 451 a, 451 b distally along beam paths toward the eye 1, and to receive one or more of an OCT return beam 301 and a visual observation reflected beam 401 returning from the eye 1 along a single beam path. In the exemplary embodiment of FIG. 2, the single beam path is directed toward a target volume 720 of ocular tissue of the eye at the iridocorneal angle.

[0030] Regarding laser beam delivery, the laser beam 201 output by the femtosecond laser source 200 passes through a beam conditioner 510, where basic beam parameters, such as beam size and divergence, are set. The beam conditioner 510 also includes additional functions, such as setting the beam power or pulse energy, and can shutter the beam on or off. After exiting the beam conditioner 510, a pair of horizontal scanning mirrors 530, 532, rotated by a galvanometer scanner, scans the laser beam 201 in two essentially orthogonal horizontal directions, e.g., the x and y directions. The laser beam 201 is then directed toward a dichroic or polarizing beam splitter 540, where it is reflected toward a beam combining mirror 601 configured to combine the laser beam 201 with the OCT beam 301.

[0031] For OCT beam delivery, the OCT beam 301 output by the OCT imager 300 passes through a beam conditioner 511 and a lateral scanner having scanning mirrors 531 and 533 .

[0032] Traveling distally toward the eye 1, after scanning mirrors 531 and 533, the OCT beam 301 is combined with the laser beam 201 by a beam combiner mirror 601. The OCT beam 301 and laser beam 201 components of the combined laser / OCT beam 210 / 301 are multiplexed and travel in the same direction. The combined laser / OCT beam 210 / 301 propagates to a second beam combining mirror 603, where it is combined with one or more optical aiming beams 451a / 451b and the visual observation beam 401 to form a combined laser / OCT / visual / aiming beam 701a.

[0033] The distally traveling combined light beam 701 passes through a focusing objective lens 750 and is reflected by an alignment mechanism 740, such as a beam folding mirror, to align with the input axis 706i of the exit lens 710. The combined light beam 701 passes through the exit lens 710 and exits the exit lens along an output axis 706o through a window 801 in the patient interface to a focal point within the target volume 720. The focusing objective lens 750, which may include a single lens or a group of lenses, is movable in the axial direction 722 by a servo motor, stepper motor, or other control mechanism. Moving the focusing objective lens 750 in the axial direction 722 changes the axial distance between the focal points of the laser beam 201 and the OCT beam 301 at the focal point.

[0034] The scattered OCT return beam 301 from the target volume 720 of ocular tissue travels proximally and returns to the OCT imager 300 along the same path as described above in reverse order. The reference beam 302 of the OCT imager 300 passes through the reference delay path and returns to the OCT imager from the movable mirror 330. The reference beam 302 is coherently combined with the OCT return beam 301 within the OCT imager 300 on its return.

[0035] 3A and 3B, the focusing objective head 700 optically and physically couples to the eye 1 via a patient interface 800. The focusing objective head 700 includes a housing 702 that houses components of the ophthalmic surgical system 1000, including, for example, an exit lens 710, an alignment mechanism 740, and a focusing objective 826. The housing 702 includes a cone attachment 704 that surrounds the exit lens 710. As described below, the cone attachment 704 is configured to couple with the patient interface 800 to secure or lock the cone attachment to the patient interface.

[0036] Regarding the exit lens 710, in one configuration, the exit lens is an aspheric lens having a concave surface 711 facing the eye and a convex surface 712 opposite the concave surface. Thus, the exit lens 710 has a meniscus shape. While the exit lens 710 shown in Figures 3A and 3B is an aspheric lens, which allows for more design freedom, in other configurations, the exit lens may be a spherical lens. Alternatively, the exit lens 710 may be a compound lens rather than a singlet.

[0037] 3A and 3B, the patient interface 800 physically couples to the eye 1 on one side and the focusing objective head 700 on the other side. The patient interface 800 serves multiple functions. It immobilizes the eye 1 relative to the components of the ophthalmic surgical system 1000, creates a sterile barrier between the components and the patient, and provides optical access between the eye and the components of the ophthalmic surgical system. The patient interface 800 may be a sterile, single-use, disposable device.

[0038] In some configurations, the patient interface 800 includes a window 801. The window 801 has a concave surface 812 that faces the eye and a convex surface 813 opposite the concave surface that faces the objective lens. Thus, the window 801 has a meniscus shape. The concave surface 812 is configured to couple to the eye via direct contact or an index-matching material, liquid, or gel disposed between the concave surface 812 and the eye.

[0039] A cone portion 803 of the patient interface 800 includes an eye attachment mechanism 804, such as a suction ring, that faces the eye 1. When the suction ring 804 contacts the eye 1, an annular cavity 805 is formed between the suction ring and the eye. A vacuum system (not shown), comprising a vacuum tube in fluid communication with the annular cavity 805 at one end and a vacuum pump at the other end, is configured to apply a vacuum within the cavity. The vacuum within the annular cavity 805 creates a vacuum force between the eye 1 and the suction ring 804, which securely attaches the eye to the patient interface 800. Removing the vacuum releases or separates the patient interface 800 from the eye 1.

[0040] 3A and 3B , the cone portion 803 of the patient interface 800 also includes a cone attachment mechanism 806 that faces the cone attachment portion 704 of the focusing objective head 700. The cone attachment mechanism 806 and the cone attachment portion 704 are configured to attach together, thereby fixing the position of the patient interface 800 relative to the focusing objective head 700. With the patient interface 800 attached to the eye 1 and the focusing objective head 700 attached to the patient interface, the position of the eye is fixed relative to the other components of the ophthalmic surgery system 1000. Attachment between the cone attachment mechanism 806 and the cone attachment portion 704 can be enabled by one or more of mechanical, vacuum, magnetic, or other principles. For example, the cone attachment mechanism 806 may be an on / off magnet attached to the cone attachment portion 704 that is magnetic when on. Turning the magnet off releases or separates the patient interface 800 from the cone attachment portion 704 of the focusing objective head 700.

[0041] 4A and 4B, a physical embodiment of an ophthalmic surgical system 1000 includes a chassis 1002, a transition arm assembly 1004, and a controller 1010. The transition arm assembly 1004 includes a first transition arm 1014 and a second transition arm 1016 that are mechanically coupled to one another, a surgical head 1006, and a multi-stage slide mechanism 1008. The first transition arm 1014 mechanically couples the transition arm assembly 1004 to the chassis 1002.

[0042] 4A and 4B in conjunction with FIG. 1, the chassis 1002 of the ophthalmic surgical system 1000 includes the laser source 200, the OCT imaging device 300, the visual observation device 400, the dual aiming beam device 450, a power supply, and various other electronics, and the surgical head 1006 of the transfer arm assembly 1004 includes components of the optical transfer system, such as the beam conditioner, scanner, and combiner 500 and beam combiner 600, and the focusing objective head 700. The electrical and optical components of the chassis 1002 and the surgical head 1006 are coupled to each other via the first transfer arm 1014 and the second transfer arm 1016 of the transfer arm assembly 1004. The controller 1010 includes the control system 100 and one or more user interfaces 110. The user interface 110 may include, for example, a display presenting a GUI with user-actuated touchscreen buttons, mechanical actuation buttons associated with one or more handles 1012 of the transfer arm assembly 1004, and mechanical actuation buttons associated with a foot pedal.

[0043] Mechanical actuation buttons associated with the one or more handles 1012 may allow for user-controlled operation of the transfer arm assembly 1004 and other components of the ophthalmic surgical system 1000. The control buttons may include one or more brake buttons that allow lateral or horizontal and vertical movement of the surgical head 1006 of the transfer arm assembly 1004. Movement of the surgical head 1006 itself is described further below.

[0044] The operation control buttons may also include one or more actuation buttons that enable various aspects of a surgical treatment, including, for example, actuation of a vacuum mechanism to secure the patient interface against eye actuation of a cone-lock mechanism to secure the patient interface 800 to the surgical head 1006, advancement of control or setting of parameters on a graphical user interface (GUI) of the controller 1010, or actuation of laser treatment.

[0045] The transfer arm assembly 1004 is operable with three degrees of motion that allow movement of the surgical head 1006 horizontally or laterally relative to a reference plane 1020 of the ophthalmic surgical system 1000, and up and down perpendicular to the reference plane. To this end, a first transfer arm 1014 of the transfer arm assembly 1004 is mounted to the chassis 1002 for rotation at a first joint / coupling about a first axis of rotation 1025 to provide a first degree of motion of the surgical head 1006 in a lateral plane 1022 (x-y plane), the lateral plane being generally parallel to the reference plane 1020 of the ophthalmic surgical system 1000. A second transfer arm 1016 of the transfer arm assembly 1004 is coupled to the first transfer arm 1014 for rotation relative to the first transfer arm at a second joint about a second axis of rotation 1027 to provide a second degree of motion of the surgical head 1006 in the lateral plane. A multi-stage slide mechanism 1008 is mounted to the second transfer arm 1016 of the transfer arm assembly 1004 to provide a third degree of motion of the surgical head 1006 in a vertical or up-down direction 1024 (z-direction) relative to a third axis of rotation 1029 of the surgical head 1006. The third axis of rotation 1029 is the axis about which the surgical head 1006 rotates.

[0046] The transfer arm assembly 1004 includes a lateral brake system comprising a first lateral brake 1031, a second lateral brake 1033, and a vertical brake system 1035. The lateral brake system and the vertical brake system are collectively referred to herein as the brake system. The first lateral brake 1031 is positioned and configured to prevent rotation of the first transfer arm 1014 about a first axis of rotation 1025. The second lateral brake 1033 is positioned and configured to prevent rotation of the second transfer arm 1016 relative to the first transfer arm 1014 about a second axis of rotation 1027. The first lateral brake 1031 and the second lateral brake 1033 cooperate to prevent movement of the surgical head 1006 in the lateral plane 1022 relative to the eye 1. A vertical braking system 1035 is associated with the multi-stage slide mechanism 1008 and configured to prevent up and down movement of components of the multi-stage slide mechanism relative to the third axis of rotation 1029. The vertical braking system 1035 can include either or both of a bidirectional brake 1037 and a unidirectional brake 1039.

[0047] In some embodiments, the brake system is normally “locked” to prevent movement of the transfer arm assembly 1004 at all degrees of motion and is changed to an “unlocked” state by releasing each of the first lateral brake 1031, the second lateral brake 1033, and the vertical brake system 1035. While the brake system is in the unlocked state, movement of the transfer arm assembly 1004 at all degrees of motion is possible. The first lateral brake 1031, the second lateral brake 1033, and the vertical brake system 1035 may be manually released, for example, by a user depressing and holding a mechanical actuation button associated with one or more of the handles 1012. To ensure safety while the brake system is released, the controller 1010 is configured to override a user-actuated brake button and return the brake system to its normal “locked” state in certain cases. This may occur, for example, in the event of a loss of power to the ophthalmic surgery system 1000 during surgery. Details regarding the operation of the brake system are provided below in the Brake System Operation section of this disclosure.

[0048] 4A and 4B, the multi-stage slide mechanism 1008 includes a coarse float counterbalance or long-reach slide mechanism 1030 mechanically coupled to the end of the second transition arm 1016 of the transition arm assembly 1004. The multi-stage slide mechanism 1008 also includes a short-reach slide mechanism 1032 mechanically coupled to the long-reach slide mechanism 1030.

[0049] The long-travel slide mechanism 1030 and the short-travel slide mechanism 1032 of the multi-stage slide mechanism 1008 each include a respective counterbalance mechanism 1044, 1066 that offsets the apparent weight of a payload mass, thereby allowing the surgical head 1006 to be safely positioned over a patient where light contact is required. The counterbalance mechanisms 1044, 1066 are designed to float the payload mass with zero apparent weight and can be adjusted to a slightly positive or slightly negative apparent weight. While the counterbalance mechanisms 1044, 1066 are shown schematically as springs in FIGS. 4A and 4B , the structural configuration of the counterbalance mechanisms may be any form, including, for example, springs, pulleys, magnets, etc., or combinations thereof.

[0050] In some embodiments, the long-travel slide mechanism 1030 comprises a coarse backplate 1040, a coarse translation plate 1042, and a counterbalance mechanism 1044. The coarse backplate 1040 is fixed to the second transition arm 1016 of the transition arm assembly 1004. The coarse translation plate 1042 moves up and down relative to the coarse backplate 1040. To this end, a mechanical coupling (not shown) or mechanical guide between the coarse backplate 1040 and the coarse translation plate 1042 allows low-friction linear translation of the coarse translation plate relative to the fixed coarse backplate. The mechanical coupling can include ball bearings or cross-roller bearings for smooth, low-friction movement of the up / down coarse translation plate 1042 relative to the coarse backplate 1040.

[0051] In some embodiments, the short-travel slide mechanism 1032 includes a fine backplate 1062, a fine motion plate 1064, and a counterbalance mechanism 1066. The fine backplate 1062 is fixed to and extends from the coarse motion plate 1042. This allows the fine backplate 1062 to move up and down with the coarse motion plate 1042. The fine motion plate 1064 moves up and down relative to the fine backplate 1062. To this end, a mechanical linkage (not shown) or mechanical guide between the fine backplate 1062 and the fine motion plate 1064 allows low-friction linear motion of the motion plate relative to the fixed plate. The mechanical linkage 1068 can include ball bearings or cross-roller bearings for smooth, low-friction movement of the fine motion plate 1064 up / down relative to the fine backplate 1062.

[0052] 5A , the long-thru slide mechanism 1030, together with the short-thru slide mechanism 1032 and the surgical head 1006 (attached to the coarse translation plate), enables a first stage of vertical displacement of the coarse translation plate 1042 between an upper limit 550 and a lower limit 552. The distance between the upper limit 550 and the lower limit 552 (or coarse float range) is typically within a range of 75 mm to 125 mm. The counterbalance mechanism 1044 of the long-thru slide mechanism 1030 is configured to reduce the force required to manually position the surgical head 1006. In some embodiments, the counterbalance mechanism 1044 of the long-thru slide mechanism 1030 is configured to provide a counterbalance force to the force of the load mass such that less than 5 Newtons (N) is required to displace or move the surgical head 1006 between the upper limit 550 and the lower limit 552.

[0053] 5B, the short-throw slide mechanism 1032 is configured to enable second-stage vertical displacement of the coarse movement plate 1042 and the fine backplate 1062 relative to the fine movement plate 1064 and the surgical head 1006 between an upper limit 554 and a lower limit 556. The distance between the upper limit 554 and the lower limit 556 (or the fine float range) is typically within a range of 10 mm to 60 mm. In some embodiments, the counterbalance mechanism 1066 of the short-throw slide mechanism 1032 is configured to provide a counterbalance force to the force of the load mass so that the downward force on the eye 1 resulting from displacement of the surgical head 1006 to the lower limit 556 does not exceed a preset level.

[0054] In some embodiments, the counterforce provided by the short-throw slide mechanism 1032 is constant within the fine float range, such that the force on the eye is between -0.5 N and +0.5 N, but not more than 0.5 N. In some embodiments, the counterforce provided by the short-throw slide mechanism 1032 varies based on the position of the surgical head 1006 within the fine float range and the direction of travel of the surgical head. For example, the short-throw slide mechanism 1032 may be configured to: 1) provide a first counterforce while the surgical head 1006 is displacing downward from the upper limit 554 to the lower limit 556, and then upward from the lower limit to the cone actuation point 558; and 2) provide a second counterforce while the surgical head 1006 is displacing upward from the cone actuation point 558. The first counterforce maintains the force on the eye in the range of 2 N to 3 N. This condition is referred to herein as a "heavy float" setting. The second counterforce maintains the force on the eye in the range of -0.5 N to +0.5 N. This condition is referred to herein as the "light float" setting.

[0055] Having generally described the mechanical structure of the transition arm assembly 1004 of the surgical system 1000, the application of the transition arm assembly in the context of an ophthalmic surgical procedure follows.

[0056] Docking Procedure As part of a surgical procedure called docking, the patient interface 800 is connected and secured to the eye 1, and the cone mount 704 of the surgical head 1006 is connected to the patient interface. The patient interface 800 is positioned between the eye 1 and the surgical head 1006 to immobilize the eye 1 relative to the ophthalmic surgical system 1000. Docking can be performed in two ways: the patient interface 800 is first connected to the eye 1 and then to the surgical head 1006, or the patient interface is first connected to the surgical head and then to the eye.

[0057] According to embodiments disclosed herein, the multi-stage slide mechanism 1008 of the transfer arm assembly 1004 is configured to enable a docking procedure that includes a coarse (or long-range) movement in which the surgical head 1006 moves toward the patient interface 800 coupled to the eye 1, followed by a fine (or short-range) movement in which the surgical head 1006 stops moving toward the patient interface. In one embodiment, during the coarse movement, the coarse movement plate 1042 of the long-range slide mechanism 1030 moves relative to the coarse backplate 1040 in a direction toward the patient interface 800. Additionally, because the short-range slide mechanism 1032 and the surgical head 1006 are attached to the coarse movement plate 1042, they also move in a direction toward the patient interface 800. The long-range movement of the surgical head 1006 brings the surgical head cone mount 704 into contact with the patient interface 800.

[0058] During fine movement, when the surgical head 1006 contacts the patient interface 800, it encounters a resistive force that stops further movement of the fine movement plate 1064 toward the patient interface. Because the surgical head 1006 is attached to the fine movement plate 1064, it also stops moving toward the patient interface 800. The stopping of the surgical head 1006 limits the force applied to the eye through the patient interface 800. However, the coarse movement plate 1042 of the long-thru slide mechanism 1030 and the fine backplate 1062 of the short-thru slide mechanism 1032 continue to move toward the patient interface 800.

[0059] To prevent damage, the multi-stage slide mechanism 1008 of the transfer arm assembly 1004 is configured to protect the eye 1 from the application of excessive force. Ideally, the force applied to the eye 1 is kept below 0.5 N for long periods of time and below 3 N for short periods of time, such as over a few seconds. In some embodiments, the force applied to the eye 1 through the patient interface 800 after the surgical head 1006 initially contacts the patient interface is in the range of 2 N to 3 N and is automatically reduced to a force below 0.5 N when the surgical head couples to the patient interface.

[0060] Figure 6 is a flowchart of a method of coupling a surgical head 1006 to a surgical site, such as the eye 1. This method may be enabled by the surgical system 1000 of Figures 4A and 4B.

[0061] In block 602, referring to FIG. 7A, the patient interface 800 is secured to the eye 1. For example, as described above with reference to FIGS. 3A and 3B, an eye attachment mechanism 804 in the form of a suction ring can be activated by applying suction from a vacuum to the annular cavity 805 between the ring and the eye 1, thereby securing the patient interface to the eye. An eye suction sensor (not shown) confirms valid coupling between the patient interface 800 and the eye 1. To this end, the eye suction sensor is configured to detect validity by measuring negative pressure in the vacuum line or the absence of airflow from the suction ring. Conversely, the presence of airflow indicates separation between the suction ring and the eye, in which case the coupling between the patient interface 800 and the eye 1 is considered invalid by the eye suction sensor.

[0062] 4A, 4B, 7A, and 7B, at block 604, movement of the surgical head 1006 is permitted. To this end, a brake release button on the handle 1012 can be actuated to release or unlock the lateral brake systems 1031, 1033 and the vertical brake system 1035 of the transfer arm assembly 1004. Releasing the lateral brake systems 1031, 1033 allows the first transfer arm 1014 and second transfer arm 1016 of the transfer arm assembly 1004 to pivot about their respective axes of rotation 1025, 1027. Thus, the surgical head 1006 may be moved laterally within the lateral plane 1022 from a first position 1100 (shown in FIG. 7A ) that places the cone mount 704 of the surgical head 1006 in approximately vertical alignment with the patient interface 800 to a second position 1102 (shown in FIG. 7B ).

[0063] 7B and 7C, releasing the vertical brake system 1035 allows vertical displacement of the surgical head 1006 by the long-thru slide mechanism 1030 toward the patient interface 800. Thus, the surgical head 1006 may be moved vertically downward in the z-direction 1024 from the second position 1102 (shown in FIG. 7B ) to a third position 1104 (shown in FIG. 7C ) to position the cone mount 704 of the surgical head 1006 within the patient interface 800. More specifically, with reference to FIGS. 7B and 7C , the coarse translation plate 1042 of the long-thru slide mechanism 1030 can slide downward relative to the coarse backplate 1040, and the counterbalance mechanism 1044 balances the load mass of the counterbalance mechanism such that the displacement force required to move the load mass either upward or downward is less than 5 N. The load mass of the counterbalance mechanism 1044 includes the surgical head 1006, the short-thru slide mechanism 1032, and the coarse translation plate 1042. 5A, the vertical range of motion of the coarse translation plate 1042 together with the short-throw slide mechanism 1032 and surgical head 1006 in this first stage (or coarse stage) is 75 mm to 125 mm, referred to herein as the "long-throw range of motion." Additionally, because the short-throw slide mechanism 1032 and surgical head 1006 are attached to the coarse translation plate 1042, they also move with the coarse translation plate.

[0064] 7C and 7D , in block 606, in response to the surgical head encountering a resistance force R, a fine float stop of the surgical head 1006 is enabled from further movement toward the patient interface 800. To this end, the lateral brake systems 1031, 1033 and the vertical brake system 1035 of the transfer arm assembly 1004 may remain unlocked by continued actuation of a brake release button. This allows further vertical downward movement of the surgical head 1006 by the long-throw slide mechanism 1030 relative to the patient interface 800 until the cone mount 704 of the surgical head 1006 encounters a resistance force R through the patient interface that is equal to or exceeds the threshold. The resistance force R stops movement of the surgical head 1006 in the z-direction 1024 by the long-throw slide mechanism 1030. In response to the resistance force R, the counterbalance mechanism 1066 of the short-throw slide mechanism 1032 balances its load mass so that the force on the patient interface 800 (and therefore the force on the eye 1) is less than 5 N. The load mass of the counterbalance mechanism 1066 includes the surgical head 1006 and the fine movement plate 1064 .

[0065] Considering further the stopping of the surgical head 1006, once the cone mount 704 encounters a threshold resistance force R via the patient interface 800, any further downward movement of the surgical head 1006 via movement of the long-throw slide mechanism 1030 is stopped by the short-throw slide mechanism 1032. More specifically, the fine movement plate 1064 of the short-throw slide mechanism 1032 stops moving, and the coarse movement plate 1042 and fine backplate 1062 continue to slide in a direction toward the patient interface 800 relative to the stopped fine movement plate 1064 and surgical head 1006. Thus, as shown in FIGS. 7C and 7D , the third position 1104 of the surgical head 1006 (shown in FIG. 7C ) is the same as the fourth position 1106 (shown in FIG. 7D ), but the respective positions of the fine backplate 1062 relative to the coarse movement plate 1042 and fine movement plate 1064 of the long-throw slide mechanism 1030 are different. As previously described with reference to FIG. 5B, the vertical range of motion of the coarse motion plate 1042 and fine backplate 1062 relative to the fine motion plate 1064 and surgical head 1006 in this second stage (or fine stage) is between 10 mm and 60 mm, referred to herein as the "short range of motion."

[0066] At block 608, the cone mount 704 of the surgical head 1006 is locked in place relative to the patient interface 800, a condition referred to herein as "cone lock."

[0067] In some embodiments, the cone lock is automated. To this end, with reference to FIG. 7D , the short-throw slide mechanism 1032 includes a sensor 1110 (schematically represented by three displacement flags) configured to have an initial actuation when the surgical head 1006 is in the fourth position 1106 (shown in FIG. 7D ), which corresponds to 1508 in FIG. 5B . Stated another way, the sensor 1110 is configured to have an initial actuation when the relative positions of the fine movement plate 1064 (to which the surgical head 1006 is attached) and the fine backplate 1062 are as shown in FIG. 7D . This initial actuation is indicated by the bottom alignment of the displacement flags. Upon initial actuation, the sensor 1110 outputs a control signal to the cone attachment mechanism of the patient interface 800, which activates the cone attachment mechanism 806. As described above with reference to FIGS. 3A and 3B , the cone attachment mechanism 806 (e.g., mechanical, vacuum, or magnetic) secures the patient interface 800 to the cone mount 704 of the surgical head 1006.

[0068] In some embodiments, the cone lock is manually operated. To this end, referring to FIG. 7D , a sensor 1110 of the short-throw slide mechanism 1032 is configured to output a measurement of the force encountered by the cone attachment portion 704 to a display on the controller 1010. The display informs the surgeon of the progress of the docking. When the display indicates a force equal to or greater than the threshold force, an actuation button on the handle 1012 can be actuated to output a control signal to the cone attachment mechanism that actuates the cone attachment mechanism 806.

[0069] In either manual or automatic operation, a cone attachment sensor (not shown) confirms valid coupling between the cone attachment portion 704 and the patient interface 800. To this end, the cone attachment sensor is configured to detect valid coupling by measuring negative pressure in the vacuum line or a lack of airflow from the cone attachment portion 704. Conversely, the presence of airflow indicates separation between the patient interface 800 and the suction ring 806, in which case coupling between the patient interface 800 and the eye 1 is deemed invalid by the eye suction sensor.

[0070] In block 610, movement of the surgical head 1006 is limited or prevented. Such movement limitation may include limiting vertical (up and down) movement of the surgical head 1006 with a long-reach slide mechanism 1030 and / or limiting lateral movement of the surgical head with a transmission arm. Such movement limitation may be enabled by one or more brakes.

[0071] With regard to limiting vertical (up and down) movement, in some embodiments, movement of the surgical head 1006 via the long-reach sliding mechanism 1030 may be limited in both directions. To this end, the vertical brake system 1035 is a bidirectional brake 1037 configured to enter a locked state and prevent vertical movement of the surgical head 1006 via the long-reach sliding mechanism 1030 in both a downward direction toward the eye 1 and an upward direction away from the eye. In some embodiments, movement of the surgical head 1006 via the long-reach sliding mechanism 1030 is limited in one direction. To this end, the vertical brake system 1035 is a unidirectional brake 1039 configured to enter a locked state and prevent vertical movement of the surgical head 1006 via the long-reach sliding mechanism 1030 in a downward direction toward the eye 1 while allowing movement in an upward direction away from the eye 1. Details regarding the operation of the brake system are provided below in the Brake System Operation section of this disclosure.

[0072] Regardless of the type of restriction on the vertical (up and down) movement of the surgical head 1006 by the long-throw sliding mechanism 1030, the vertical movement of the surgical head is not restricted by the short-throw sliding mechanism 1032. More specifically, the short-throw sliding mechanism 1032 does not have a brake that limits or prevents vertical (up and down) movement of the fine movement plate 1064 (to which the surgical head 1006 is attached) relative to the fine backplate 1062. Thus, while movement of the surgical head 1006 toward the eye can be stopped when a resistive force R is encountered during docking (as shown in FIG. 7C ), the short-throw sliding mechanism 1032 allows free upward vertical movement of the surgical head 1006. This upward movement, combined with the force-controlling effect of the counterbalance mechanism 1066, helps reduce forces on the eye 1 in the event of inadvertent movement of the patient's head or the operating table below the patient. Side and vertical lift forces are limited by breaking the suction coupling between the patient interface 800 and the eye 1. For this reason, the aspiration vacuum pressure is adjusted to be sufficient to stabilize the eye, but not excessive, to allow for damping of the suction force.

[0073] In some embodiments, the restriction of movement of the surgical head 1006 by the long-reach slide mechanism 1030 is automated. To this end, referring to FIG. 7E , the sensor 1110 is configured to have a second actuation when the surgical head 1006 is in a fifth position 1108 (shown in FIG. 7E ), which corresponds to position 560 in FIG. 5B . Stated differently, the sensor 1110 is configured to have a second actuation when the relative position of the fine movement plate 1064 (to which the surgical head 1006 is attached) and the fine backplate 1062 is as shown in FIG. 7E . This second actuation is indicated by the top alignment of the displacement flag. During the second actuation, the sensor 1110 outputs a control signal to the brake system that locks the lateral brake systems 1031, 1033 and the vertical brake system 1035 of the transfer arm assembly 1004, thereby restricting the movement of the surgical head 1006.

[0074] In some embodiments, the restriction of movement of the surgical head 1006 is manual. To this end, referring to FIG. 7E , the automatic locking of the lateral brake systems 1031, 1033 and vertical brake system 1035 of the transfer arm assembly 1004 by the sensor 1110 of the short-throw slide mechanism 1032 can be overridden by user action. For example, the display of the controller 1010 can indicate a cone lock status, and the actuation button on the handle 1012 can be actuated accordingly to lock the brake system. For example, if cone lock is achieved before the second actuation of the sensor 1110, the surgeon can manually lock the brake system by releasing the actuation button, so that the brake system assumes its normally locked state.

[0075] In block 612, the apparent weight of the surgical head 1006 is reduced. This reduction can occur upon initial actuation of the sensor 1110, described above in the context of the automated cone lock. Upon initial actuation, the sensor 1110 outputs a control signal to a fine float mechanism associated with the short-throw slide mechanism, which adjusts the counterbalance force of the short-throw slide mechanism 1032. Adjusting the counterbalance force by the fine float mechanism relieves the force acting on the eye during the docking process. The fine float mechanism can be an additional spring, pneumatic, or magnetic device configured to balance the force of the short-throw slide mechanism so that the force on the eye 1 (either a positive push down or a negative pull up) is close to zero. Details of the magnetic configuration of the fine float mechanism for adjusting the counterbalance force of the short-throw slide mechanism 1032 are described below with reference to FIGS. 10A and 10B.

[0076] The fine float counterbalance mechanism of the short-throw slide mechanism 1032 functions as a variable force mechanism to provide an initial high docking force for part of the docking procedure, which is then reduced as soon as cone lock is achieved. This reduction in force minimizes the duration that heavier downward pressure is applied to the eye 1. The initial higher pressure, applied for a few seconds, helps achieve more reliable contact between the cone attachment portion 704 and the inner surface of the patient interface 800 to achieve cone lock. Once cone lock is achieved, the weight of the fine float on the eye can be reduced.

[0077] In block 614, once the laser treatment is complete, the surgical head 1006 is released from the patient interface 800, and the patient interface is released from the eye 1. To this end, the eye attachment mechanism 804 and the cone attachment mechanism 806 are stopped manually or automatically by the controller 1010. In some embodiments, the cone attachment 704 may include a mechanical actuator positioned and configured to depress the cone attachment to break the surface tension between the top surface of the window 801 of the patient interface 800 and the mating glass surface of the surgical head 1006.

[0078] In block 616, movement of the surgical head 1006 is permitted. To this end, a brake release button on the handle 1012 can be actuated to release or unlock the lateral brake systems 1031, 1033 and the vertical brake system 1035 of the transfer arm assembly 1004. This allows the surgical head 1006 to be moved away from the eye 1. As a safety feature for undocking, a second sensor, e.g., a displacement or force sensor, associated with the short-throw slide mechanism 1032 can detect excessive negative force on the eye 1 and output a control signal to lock the vertical brake system 1035 to prevent upward movement of the surgical head 1006 by the long-throw slide mechanism 1030 before the eye 1 is detached from the surgical head 1006. The sensor may also output a control signal to stop either or both of the eye attachment mechanism 804 and the cone attachment mechanism 806 of the patient interface 800, thereby detaching the surgical head 1006 from the eye. After the eye 1 is detached from the surgical head 1006 , the vertical brake system 1035 can be unlocked to allow upward movement of the surgical head 1006 by the long-reach slide mechanism 1030 .

[0079] With respect to the deactivation of the eye attachment mechanism 804 securing the patient interface 800 to the eye 1, such deactivation and resulting decoupling between the patient interface and the eye may be confirmed by the surgical system 1001 prior to unlocking the vertical brake system 1035. In one embodiment, deactivation is facilitated and confirmed by applying a burst of positive pressure to the eye attachment mechanism 804, e.g., the suction ring, and sensing a positive airflow indicating decoupling between the eye 1 and the suction ring.

[0080] With respect to the deactivation of the cone attachment mechanism 806 securing the patient interface 800 to the cone mount 704, such deactivation and resulting decoupling between the patient interface and the eye may be confirmed by the surgical system 1001 prior to unlocking the vertical brake system 1035. In one embodiment, deactivation is facilitated and confirmed by applying a burst of positive pressure to the cone attachment mechanism 806, e.g., the suction ring, and sensing a positive airflow indicating decoupling between the patient interface 800 and the suction ring.

[0081] 8A and 8B, during a docking procedure using a surgical system 1000 configured in accordance with embodiments disclosed herein, the force applied to a surgical site, e.g., an eye, can be controlled to decrease to near 0 N upon completion of docking. The graphs in FIGS. 8A and 8B show downward force on a model eye during a docking test. The graphs show a force of 0 N before docking, a force between 2 N and 3 N for several seconds during docking, a cessation of force increase, and a decrease in force to less than 0.5 N.

[0082] Further considering the graphs of Figures 8A and 8B, during period A, the docking procedure has not yet begun and the force on eye 1 is close to 0N.

[0083] Between point B (the start of the docking procedure) and point C (initial engagement of the cone mount 704 with the patient interface 800), the downward force on the eye 1 increases. At point C, the counterbalance mechanism 1066 of the short-throw slide mechanism 1032 limits the force on the eye 1 to less than −2 N.

[0084] At point D, the cone lock is activated and the brake system is locked, preventing further downward movement of the surgical head 1006 by the long-travel slide mechanism 1030. This limit on the movement of the surgical head 1006 prevents a further increase in force on the eye 1.

[0085] Between points D and F, the downward force on eye 1 decreases. During this time, at point E, the counterbalance mechanism 1066 of the short-distance sliding mechanism 1032 adjusts to limit the force on eye 1 to less than 0.5 N. At point F, the counterbalance mechanism 1066 of the short-distance sliding mechanism 1032 limits the force on eye 1 to near 0 N.

[0086] At point G (FIG. 8A), a residual force in the direction of eye 1 may be exerted on the eye after docking due to mechanical tolerances associated with the counterbalance mechanism 1066 of the short-throw slide mechanism 1032. At point H (FIG. 8B), a residual force opposite to the direction of eye 1 may be exerted on the eye. This residual force pulls eye 1 upward.

[0087] Multi-stage slide mechanism 9A and 9B, in some embodiments, the multi-stage slide mechanism includes a long-reach slide mechanism 1030 having a pulley counterbalance mechanism 1044 and a short-reach slide mechanism 1032 having a magnetic counterbalance mechanism 1066. The pulley counterbalance mechanism 1044 is also referred to herein as a coarse float counterbalance, and the short-reach slide mechanism 1032 is also referred to as a fine float counterbalance.

[0088] Pulley counterbalance mechanism 9A and 9B , in some embodiments, a pulley counterbalance mechanism 1044 can include a variable radius input pulley 1048 and a constant radius output pulley 1050 coupled to one another about a common bearing 1052. An input spring 1054 (extension or compression) having a length l is attached to the variable radius input pulley 1048 and coupled to an input cable 1056 that wraps around the variable radius input pulley. An output cable 1058 is attached to the constant radius output pulley 1050, wraps around the constant radius output pulley, and is coupled to a load mass 1060 of the pulley counterbalance mechanism 1044. The load mass 1060 of the pulley counterbalance mechanism 1044 includes the surgical head 1006, the short-throw slide mechanism 1032, and the coarse translation plate 1042.

[0089] The variable radius input pulley 1048 and the constant radius output pulley 1050 rotate coaxially about a common bearing 1052 and are held in fixed rotational phase with each other. As the load mass 1060 moves up and down, the input cable 1056 rotates the variable radius input pulley as the output cable 1058 is wrapped around or unwound from the output side of the variable radius input pulley 1048. This causes a subsequent wrapping / unwrapping of the input cable 1056 which changes the length l of the input spring 1054, increasing the input force F generated by the input spring. i teeth, F i =k x where k is the spring constant of the input spring 1054 and x is the change in length l of the input spring.

[0090] A constant output force F at a load mass of 1060 o To achieve this, one or both of the radius r1 of the variable radius input pulley 1048 and the radius r2 of the constant radius output pulley 1050 are varied. The input cable 1056 and the output cable 1058 pull tangent to the variable radius input pulley 1048 and the constant radius output pulley 1050, respectively, generating a torque about the common bearing 1052. To balance the load mass 1060, the input torque T generated by the tangential pull of the input cable 1056 is i is the output torque T generated by the tangential pull of the output cable 1058 o The torque is equal to F=k·x=T / r where k is the spring constant of the input spring 1054, x is the change in length l of the input spring, T is the required torque, and r is the imaginary radius of the pulley perpendicular to the acting tangent of the cable.

[0091] Either the radius r1 of the variable radius input pulley 1048, the radius r2 of the constant radius output pulley 1050, or the rotational phase of the two pulleys relative to each other can be varied to achieve a constant counterbalance force CB, or a variable counterbalance force determined by either a linear spring constant different from that of the input spring 1054, or a non-linear spring constant.

[0092] The pulley counterbalance mechanism 1044 provides a counterbalance force CB that lifts the load mass 1060 through pulley bearings and cable bending, which are the primary sources of friction associated with the pulley counterbalance mechanism 1044 (apart from the mechanical coupling between the coarse backplate 1040 and the coarse translation plate 1042). The result is low friction and hysteresis. With its cables 1056, 1058 wrapped around pulleys 1048, 1050 that rotate on precision bearings, the pulley counterbalance mechanism 1044 provides smooth motion that behaves like a mass counterbalance, but without the disadvantages of bulky masses.

[0093] The pulley counterbalance mechanism 1044 is configured to allow adjustment of the counterbalance force C. To this end, an adjustable spring tensioner 1084 associated with the input spring 1054 allows for preload setting depending on the load mass 1060. Once adjusted to the desired counterbalance force C, the counterbalance force remains constant.

[0094] Magnetic Counterbalance Mechanism 9A and 9B, in some embodiments, the magnetic counterbalance mechanism 1066 includes a set of magnetic couplings coupled to the magnetic counterbalance mechanism's load mass 1092. The set of magnetic couplings may include one, two, three, or more magnetic couplings. The magnetic counterbalance mechanism 1066 provides a counterbalance force C to the load mass 1092 without physically contacting the load mass. As a result, there is minimal friction and hysteresis, no physical wear of the coupled components (e.g., the magnetic counterbalance mechanism 1066 and the load mass), and no debris is generated by moving parts.

[0095] The load mass 1092 of the magnetic counterbalance mechanism 1066 includes the surgical head 1006 and the fine movement plate 1064. In one configuration, the set of magnetic couplings includes a first magnetic coupling 1071, a second magnetic coupling 1073, and an intermediate magnetic coupling 1072. Each of the magnetic couplings 1071, 1072, 1073 includes a fine movement magnet positioned between a pair of ferromagnetic metal plates. The fine movement magnet is mechanically coupled to the fine movement plate 1064, while the pair of metal plates is mechanically coupled to the fine backplate 1062, which in turn is coupled to the coarse movement plate 1042.

[0096] 10A and 10B, an intermediate magnetic coupling 1072 of the magnetic counterbalance mechanism 1066 is configured to adjust the counterbalance weight of the load mass 1092. The intermediate magnetic coupling 1072 includes an intermediate fine movement magnet 1075 that is mechanically coupled to the load mass 1092 via the fine movement plate 1064. The intermediate magnetic coupling 1072 is positioned between a pair of metal plates including a magnetic pivot plate 1070 and a fixed plate 1074 that are mechanically coupled to the fine backplate 1062, which in turn is coupled to the coarse movement plate 1042.

[0097] The intermediate fine mobile magnet 1075 is a permanent magnet that is magnetized through its thickness so that the magnet is much longer in the direction perpendicular to its magnetic pole orientation. The magnetic pivot plate 1070 is shorter in length than the intermediate fine mobile magnet 1075. Thus, when the magnetic pivot plate 1070 is positioned near the long end of the intermediate fine mobile magnet 1075, the magnetic pivot plate is attracted to the surface of the fine mobile magnet as well as to a central position along the length of the magnet. When the magnetic pivot plate 1070 is held away from the intermediate fine mobile magnet 1075, the force pulling the magnetic pivot plate toward the center of the fine mobile magnet's long axis generates a nearly constant force in that direction.

[0098] The counterbalance force CB provided by the magnetic counterbalance mechanism 1066 is determined by controlling the air gap 1082 between the magnetic pivot plate 1070 and the intermediate fine movement magnet 1075. The air gap 1082 between the magnetic pivot plate 1070 and the intermediate fine movement magnet 1075 can be adjusted to increase or decrease the counterbalance force of the magnetic counterbalance mechanism 1066, opposing the force of the load mass 1092. The magnetic counterbalance mechanism 1066 is modular in that it can be configured with multiple magnets of parallel or variable magnet strengths that can be mixed and balanced to achieve a desired counterbalance lifting force.

[0099] The magnetic counterbalance mechanism 1066 also includes a wedge motor assembly configured to adjust the size of an air gap 1082 between the intermediate fine movement magnet 1075 and the magnetic pivot plate 1070. The wedge motor assembly includes a motor 1076 and a wedge 1078 coupled to a rod 1080 extending from the motor. An electronically controlled actuator that operates the motor 1076 to move the wedge 1078 up and down, thereby adjusting the size of the air gap 1082, can be used to set the apparent weight of the load mass 1092 to one of several calibrated set points. If fully continuous control of the apparent weight of the load mass 1092 is desired, the electronically controlled actuator can be paired with a load sensor to measure the instantaneous weight of the load mass and adjust the air gap 1082 in real time.

[0100] According to embodiments disclosed herein, the magnetic counterbalance mechanism 1066 is configured to transition between a "heavy" mode and a "light" mode. By changing the size of the gap 1082, in heavy mode, the size of the gap 1082 is larger than the size of the gap in light mode. During heavy mode, the larger the gap 1082, the smaller the counterbalance force on the load mass 1092, including the surgical head 1006. Therefore, the apparent weight of the load mass 1092 is heavier, and a larger downward force is applied to the eye 1. Conversely, during light mode, the smaller the gap 1082, the larger the counterbalance force on the load mass 1092, including the surgical head 1006. Therefore, the apparent weight of the load mass 1092 is lighter, and a smaller downward force is applied to the eye 1. In one configuration, the weight applied to the eye 1 is in the range of 100 g to 300 g when the magnetic counterbalance mechanism 1066 is in heavy mode and in the range of −100 g to +100 g when the magnetic counterbalance mechanism 1066 is in light mode.

[0101] As discussed above, the intermediate magnetic coupling 1072 includes a structure arranged to provide an air gap 1082 that can be adjusted to set the apparent weight of the payload mass 1092. While the structure of the embodiment of Figures 10A and 10B includes a pair of metal plates and an intermediate magnet, other configurations are contemplated. For example, the air gap 1082 may be defined by a pair of spaced-apart magnets or a metal plate spaced from a magnet.

[0102] Control System 11 , features of the surgical system 1000 during the docking procedure are controlled by a controller 1010 based on sensor signals 1121 from one or more sensors 1122 and control signals 1123 from one or more operator controls 1124. The controller 1010 includes a brake control module 1120, an attachment module 1126, and a variable force module 1128. The brake control module 1120 includes program logic that processes the signals 1121, 1123 to determine how to set the state (locked or unlocked) of one or more of the first lateral brake 1031, the second lateral brake 1033, and the vertical brake system 1035 of the brake system 1130. The attachment module 1126 includes program logic that processes the signals 1121, 1123 to determine the cone lock state (on / off) of the cone attachment mechanism 1132. The variable force module 1128 contains program logic that processes the signals 1121, 1123 to determine how to set the mode (heavy / light) of the fine float counterbalance mechanism 1134.

[0103] The sensor 1122 can include a sensor 1110 associated with the short-range slide mechanism 1032. As described with reference to Figures 7D and 7E, this sensor 1110 can be a displacement sensor that provides sensor signals 1121 indicative of the position of the fine movement plate 1064 relative to the fine backplate 1062. Because the surgical head 1006 is attached to and moves with the fine movement plate 1064, these sensor signals 1121 also indicate the position of the surgical head relative to the eye 1. These sensor signals 1121 can also indicate positive and negative forces at the eye 1. The displacement sensor 1110 can have a mechanical configuration (e.g., limit switch, mechanical flag, lever, etc.), an electromagnetic configuration (e.g., Hall Effect sensor), an optical configuration, or any other known configuration.

[0104] In some embodiments, the displacement sensor 1110 also functions as a force sensor. In this case, the sensor signal 1121 provided by the sensor 1110 can be correlated to force measurements at the cone mount 704 of the surgical head 1006, which in turn correlates to forces applied to the eye 1 via the cone mount. These forces at the eye 1 can be positive downward forces applied to the eye or negative upward traction forces applied to the eye. The negative and positive force measurements can be obtained by measuring the displacement of the fine movement plate 1064 of the short-throw slide mechanism 1032 based on the force-displacement curve of the fine movement plate 1064. This curve can be measured and set to the desired shape during the manufacturing and calibration process by adjusting the balance spring and / or balance magnet of the short-throw slide mechanism 1032.

[0105] The sensor signal 1121 from the displacement sensor 1110 is provided to the brake control module 1120, where it is processed by program logic to determine whether the controller 1010 should lock either or both of the lateral brake systems 1031, 1033 and the vertical brake system 1035. One example of brake control is disclosed above in block 610 of FIG. 6, in which movement of the surgical head 1006 is limited based on the displacement sensor 1110. In some embodiments, the brake control module 1120 is configured to determine the direction of movement of the surgical head 1006 based on changes in the sensor signal 1121, which correspond to changes in the position of the surgical head over time. Based on the direction of movement, the brake control module 1120 can determine whether the controller 1010 should lock either or both of the lateral brake systems 1031, 1033 and the vertical brake system 1035. For example, the controller 1010 may control the state of the one-way brake 1039 to unlock the brake in the allowed direction and lock the brake in the prohibited direction.

[0106] The sensor signal 1121 from the displacement sensor 1110 is provided to the attachment module 1126, where it is processed by program logic to determine whether the controller 1010 should set the cone attachment mechanism 1132 on or off. An example of cone attachment control is disclosed above in block 608 of FIG. 6, where the cone attachment is turned on based on the displacement sensor 1110. Considering cone attachment control further, the displacement sensor 1110 may be configured to output a sensor signal 1121 that causes the controller 1010 to activate a cone lock based on the position of the fine movement plate 1064 relative to the fine backplate 1062, which corresponds to a threshold weight or force on the eye. The threshold force for activation of the cone lock may be set between 0.1 N and 0.4 N. Note that in some embodiments, the cone lock is typically triggered at a low value, e.g., 0.15 N, and the force on the eye is not greater than this value.

[0107] The sensor signal 1121 from the displacement sensor 1110 is provided to the variable force module 1128, where it is processed by program logic to determine whether the controller 1010 should set the fine float counterbalance mechanism 1134 to light mode or heavy mode. The logical operation of the variable force module 1128 is described below in the "Variable Force Control" section.

[0108] The sensor 1122 may include an eye suction sensor configured to verify activation and deactivation of effective coupling between the patient interface 800 and the eye 1. In one embodiment, the eye suction sensor is configured to measure vacuum pressure or the absence of airflow from the eye attachment mechanism 804. In another embodiment, the eye suction sensor is configured to apply bursts of positive pressure to the eye attachment mechanism 804 of the patient interface 800, for example within a suction ring, sense airflow through the eye attachment mechanism, and output a sensor signal indicative of the airflow.

[0109] The sensor signal 1121 from the eye-mounted sensor is provided to the attachment module 1126, where it is processed to determine the suction state (on / off) of the eye-mounted mechanism 804. For example, a sensor signal 1121 from the eye-mounted sensor representing a negative air flow indicates effective and secure coupling between the suction ring 804 and the eye 1, while a sensor signal representing a positive air flow indicates separation between the suction ring and the eye.

[0110] Other types of sensors may be used to confirm activation and deactivation of effective coupling between the patient interface 800 and the eye 1. For example, a weight sensor positioned at the contact interface between the patient interface 800 and the eye 1 may be configured to sense a threshold weight or force on the eye.

[0111] The sensor 1122 may include a cone attachment sensor configured to verify activation and deactivation of a valid coupling between the cone attachment portion 704 of the surgical head 1006 and the patient interface 800. In one embodiment, the sensor measures negative air pressure applied to the cone attachment mechanism 806. In another embodiment, the cone attachment sensor is configured to apply bursts of positive pressure to the cone attachment mechanism 806, for example, within a suction ring of the patient interface 800, sense air flow through the cone attachment mechanism, and output a sensor signal indicative of the air flow.

[0112] The sensor signal 1121 from the cone attachment sensor is provided to the attachment module 1126 where it is processed to determine the cone lock status (on / off) of the cone attachment mechanism 1132. For example, a sensor signal 1121 from the cone attachment sensor representing negative airflow indicates a valid and secure connection between the patient interface 800 and the suction ring 806, while a sensor signal representing positive airflow indicates a separation between the patient interface and the suction ring.

[0113] Other types of sensors 1122 may be used to provide sensor signals 1121 confirming activation and deactivation of effective coupling between the cone mount 704 of the surgical head 1006 and the patient interface 800. For example, a weight sensor positioned at the contact interface between the exterior surface of the cone mount 704 relative to the interior of the patient interface 800 may be configured to sense a weight or force on the patient interface and provide a sensor signal 1121 indicative of the sensed weight or force to the attachment module 1126, which is compared to a threshold weight or force to determine the coupling status between the cone mount 704 of the surgical head 1006. As another example, a position sensor may be positioned relative to the cone mount 704 and the interior of the patient interface 800 and configured to sense the position of the exterior surface of the cone mount relative to the interior of the patient interface and provide a sensor signal 1121 indicative of the sensed position to the attachment module 1126, which is compared to a threshold to determine the coupling status between the cone mount 704 of the surgical head 1006.

[0114] The sensor signal 1121 from the cone mount sensor is provided to the brake control module 1120 where it is processed by program logic to determine whether the controller 1010 should lock either or both of the lateral brake systems 1031, 1033 and the vertical brake system 1035. In some embodiments, a sensor signal 1121 indicating valid coupling between the cone mount 704 and the patient interface 800 causes the controller 1010 to lock the lateral brake systems 1031, 1033 to prevent lateral movement of the surgical head 1006 and lock the vertical brake system 1035 to prevent both a positive downward force on the eye 1006 and a negative upward traction force on the eye 1006.

[0115] The operator controls 1124 may include the aforementioned brake release button that may be actuated by an operator to output a control signal 1123 indicating the button's pressed or released state. The control signal 1123 is provided to the brake control module 1120, where it is processed by program logic to determine whether the controller 1010 should release or unlock the lateral brake systems 1031, 1033 and the vertical brake system 1035 of the transfer arm assembly 1004. Note that a brake release initiated via the operator controls 1124 may be overridden by a sensor signal 1121 emanating from the sensor 1122.

[0116] Variable Force Control The variable force module 1128 includes program logic that determines whether to set the fine float counterbalance mechanism 1134 to a light mode or a heavy mode. As previously described, in light mode, the apparent weight of the payload mass, including the head 1006, is less than the apparent weight in heavy mode. In some embodiments, the logic of the variable force module 1128 sets the fine float counterbalance mechanism 1134 to the light mode (lightweight) when there is one or more of: 1) the absence of a control signal 1123 indicating a brake release; 2) a sensor signal 1121 from a cone-mounted sensor indicating effective coupling between the head 1006 and the patient interface 800; and 3) a sensor signal 1121 from an eye-mounted sensor indicating effective coupling between the patient interface 800 and the anatomical site 1.

[0117] In some embodiments, if there is one or more of: 1) no control signal 1123 indicating brake release; 2) a sensor signal 1121 from a cone-mounted sensor indicating valid coupling between the head 1006 and the patient interface 800; and 3) a sensor signal 1121 from an eye-mounted sensor indicating valid coupling between the patient interface 800 and the anatomical site 1, the logic of the variable force module 1128 sets the fine float counterbalance mechanism 1134 to heavy mode (weight).

[0118] Brake system 4A and 4B, the surgical system 1000 includes a brake system having a first lateral brake 1031, a second lateral brake 1033, and a vertical brake system 1035. The first lateral brake 1031 is positioned and configured to prevent rotation of the first transition arm 1014 about a first axis of rotation 1025. The second lateral brake 1033 is positioned and configured to prevent rotation of the second transition arm 1016 relative to the first transition arm 1014 about a second axis of rotation 1027. The first lateral brake 1031 and the second lateral brake 1033 cooperate to prevent movement of the surgical head 1006 in the lateral plane 1022 relative to the eye 1. A vertical brake system 1035 is associated with the multi-stage slide mechanism 1008 and is configured to prevent up and down movement of the components of the multi-stage slide mechanism relative to the third axis of rotation 1029, thus preventing movement of the surgical head 1006 in the z-direction 1024. The vertical brake system 1035 can include either or both of a bidirectional brake 1037 and a unidirectional brake 1039.

[0119] Generally, the brake system is configured to transition between a locked state and an unlocked state. The brake system is normally in the locked state, during which lateral movement of the surgical head 1006 via the transfer arm assembly 1004 is prevented by locking the first lateral brake 1031 and the second lateral brake 1033, and vertical movement of the surgical head via the long-reach slide mechanism 1030 is prevented by locking the vertical brake system 1035. In the unlocked state, lateral movement of the surgical head 1006 via the transfer arm assembly 1004 is permitted by releasing the first lateral brake 1031 and the second lateral brake 1033, and movement of the surgical head via the long-reach slide mechanism 1030 is permitted by releasing the vertical brake system 1035.

[0120] More specifically, with respect to the vertical brake system 1035, when the bidirectional brake 1037 is in an unlocked state, movement of the surgical head 1006 via the long-reach sliding mechanism 1030 is permitted in both an upward direction away from the eye 1 and a downward direction toward the eye 1. When the unidirectional brake 1039 is in an unlocked state, movement of the surgical head 1006 via the long-reach sliding mechanism 1030 is permitted in an upward direction away from the eye 1 and is prevented in a downward direction toward the eye.

[0121] Considering further the vertical braking system 1035, as disclosed above, the vertical braking system can include either or both of a bidirectional brake 1037 and a unidirectional brake 1039. A unidirectional brake 1039, particularly a fully mechanical unidirectional brake, configured to operate in parallel with the bidirectional brake 1037 can function as a backup safety device to mitigate against malfunction of the sensor 1122, the brake control module 1120, or operator error.

[0122] The bidirectional brake 1037 is configured to transition between a locked state in which vertical movement of the surgical head 1006 via the long-distance sliding mechanism 1030 is prevented in both a downward direction toward the eye 1 and an upward direction away from the eye, and an unlocked state in which vertical movement of the surgical head 1006 via the long-distance sliding mechanism 1030 is possible in both a downward direction toward the eye 1 and an upward direction away from the eye.

[0123] The one-way brake 1039 is configured to transition between a bidirectional unlocked state and a one-way unlocked state. In the bidirectional unlocked state, vertical movement of the surgical head 1006 via the long-reach sliding mechanism 1030 is permitted both downward toward the eye 1 and upward away from the eye. In the one-way unlocked state, vertical movement of the surgical head 1006 via the long-reach sliding mechanism 1030 is prevented in the downward direction toward the eye 1 but is permitted in the upward direction away from the eye. In a vertical brake system 1035 having both a bidirectional brake 1037 and a one-way brake 1039, the one-way brake overrides the bidirectional brake in the unlocked state and prevents the surgical head 1006 from moving downward toward the eye 1.

[0124] Further considering the one-way brake 1039, it provides a safety feature by limiting or preventing downward movement of the surgical head 1006 toward the eye 1 during different stages of the docking procedure and the surgical procedure, while allowing upward movement away from the eye 1. For example, after the surgical head 1006 is locked to the patient interface ( FIG. 6 , block 608), placing the one-way brake 1039 in an unlocked state prevents further downward force on the eye 1 while simultaneously allowing upward movement of the surgical head away from the eye in the event of patient movement. As another example, placing the one-way brake 1039 in a one-way unlocked state prevents movement of the surgical head 1006 toward the eye if the cone mount 704 is not properly aligned with the patient interface 800 such that the cone lock sensor does not detect valid coupling between the cone mount and the patient interface. For example, without the one-way brake 1039, a user may apply excessive force to the eye 1 in an attempt to properly align and couple the cone mount 704 with the patient interface 800.

[0125] The one-way brake 1039 may be an electromechanical brake or a mechanical brake.

[0126] The exemplary electromechanical one-way brake 1039 may be a conventional bi-directional brake configured to be set to one of a bi-directional locked state or a one-way unlocked state. Setting the initiation set point for activation of the electromechanical one-way brake may be achieved by adjusting the operation of the displacement sensor 1110. In one configuration, the displacement sensor 1110 may be set so that the force level that activates the one-way brake is approximately 0.6 N.

[0127] An exemplary mechanical one-way brake 1039 includes a mechanical friction mechanism and a ratchet consisting of a linear rack with asymmetrical teeth and a tooth-engaging pawl.

[0128] 12A, 12B, and 12C, the mechanical one-way brake 1039 may be a mechanical mechanism configured to utilize the difference in friction between surfaces when sliding or rolling. In one configuration, the mechanical mechanism of the one-way brake 1039 includes a wedge space 1202 constructed between a first surface 1204 of a coarse backplate 1040 and a second surface 1206 of a coarse translation plate 1042, and a roller 1208 located within the wedge space 1202. The roller 1208 is configured to slide along the length of the wedge and is coupled to an actuator 1210 by a push rod 1212. The actuator 1210 is configured to position the roller 1208 along the length of the wedge space 1202 so that it contacts only the first surface 1204 (as shown in FIG. 12A) or both the first and second surfaces 1206 (as shown in FIG. 12B). Actuator 1210 (with rollers 1208 ) is mounted on short-throw slide mechanism 1032 and moves with fine movement plate 1064 .

[0129] 12A and 12B , as the fine translation plate 1064 rises from the position shown in FIG. 12A to the position shown in FIG. 12B , the actuator 1210 pushes the roller 1208, causing it to roll along the first surface 1204 of the coarse backplate 1040 into the narrow portion of the wedge space 1202, until the roller contacts the first surface 1204 and the second surface 1206 of the coarse translation plate 1042. This action by the actuator 1210 presses the roller 1208 firmly against the second surface 1206 of the coarse translation plate 1042, preventing further upward movement of the roller. With the roller 1208 sandwiched between the opposing surfaces 1204, 1206 of the coarse backplate 1040 and the coarse translation plate 1042, the coarse translation plate is prevented from moving toward the reference surface 1020. This initiates the one-way braking action of the long-travel slide mechanism 1030. In other words, the mechanical one-way brake is in a locked state. Setting the initiation set point for actuation of the one-way brake can be accomplished by adjusting the length of the push rod 1212 of the actuator 1210 or by adjusting the width of the wedge space 1202. In one configuration, the force level that actuates the one-way brake is set to be approximately 0.6 N.

[0130] 12C, the push rod 1212 of the actuator 1210 can include a light force compression spring of 0.1 N or less that allows compression of the push rod 1212 after the one-way brake is activated. This allows further upward movement of the surgical head 1006 if the patient moves underneath the surgical head and pushes the fine movement plate 1064 further upward.

[0131] safety features 11, the control system may be configured to implement various safety features. For example, the brake control module 1120 may be configured to lock the vertical brake system 1035 when both the eye-mounted sensor and the cone-mounted sensor provide sensor signals 1121 indicating valid coupling to prevent lifting of the surgical head 1006.

[0132] In some embodiments, the vertical brake 1035 is configured to enter a locked state in the event of a power failure, however, the holding force of the vertical brake 1035 is set at a level such that the surgical head 1006 can be manually lifted upward and away from the patient without excessive force from the operator.

[0133] An additional safety feature prevents the surgical head 1006 from being lifted at the end of a procedure while the patient is still docked, the eye attachment mechanism is active, and the cone attachment mechanism is active. It functions as follows: To deactivate the eye attachment mechanism, a burst of positive pressure is applied to the suction ring of the patient interface 800, drawing in air. This prevents a vacuum from still being present on the suction ring even though the vacuum pump has reduced the vacuum pressure to zero. This can occur if a fluid or high viscosity gel blocks the vacuum port or the tubing connected to the patient interface 800. Applying a short burst of positive pressure and airflow into the patient interface 800 ensures that any obstructions in the vacuum line are not blocked. Sensing and verifying positive airflow or pressure confirms that the patient interface 800 has been disconnected and that the brake system can be released for undocking.

[0134] 13 is a flowchart of a method for moving the head of a medical system relative to an anatomical site to protect against unwanted forces on the anatomical site, which may be enabled by a medical system such as the surgical system 1000 disclosed herein.

[0135] 4A and 4B, the method may be enabled by a medical system including a transfer arm assembly having a head 1006 with an end portion disposed facing a reference surface 1020 of the medical system 1000 and a multi-stage slide mechanism 1008 coupled to the head. The multi-stage slide mechanism 1008 includes a long-distance slide mechanism 1030 (or a coarse float mechanism) and a short-distance slide mechanism 1032 (or a fine float mechanism). The long-distance slide mechanism 1030 (to which the head 1006 is attached via the short-distance slide mechanism 1032) is configured to move the head toward the reference surface 1020. The reference surface 1020 may correspond, for example, to a bed on which a patient having an anatomical site can lie during treatment. The short-distance slide mechanism 1032 is configured to stop movement of the head toward the reference surface 1020 in response to resistance to continued movement of the head 1006 toward the reference surface 1020.

[0136] 13 and with further reference to FIGS. 7A and 7B, a method for moving the head 1006 of the medical system 1000 relative to an anatomical site to protect against unwanted forces on the anatomical site begins at block 1302, where the head 1006 is moved in a direction toward the anatomical site, e.g., eye 1, by a long-throw sliding mechanism 1030. Referring to FIG. 7B, movement of the long-throw sliding mechanism 1030 toward the anatomical site can result from application of a downward force F to the handle 1012. The head 1006 is attached to the long-throw sliding mechanism 1030 via a short-throw sliding mechanism 1032 and moves with the long-throw sliding mechanism.

[0137] 7C and 7D , in response to a resistance (or reaction) force against movement of the head 1006 in a direction toward the anatomical location 1, the method proceeds to block 1306 where further movement of the head 1006 in a direction toward the anatomical location is stopped by the short-throw slide mechanism 1032. The resistance force R (or reaction) against movement of the head 1006 in a direction toward the anatomical location 1 occurs as the head 1006 moves further downward from the position shown in FIG. 7B to the position shown in FIG. 7C. In the position of the head 1006 shown in FIG. 7C, initial contact between the cone mount 704 of the head and the interior of the patient interface 800 results in a resistance force R. The stopping of further movement of the head 1006 in a direction toward the anatomical location by the short-throw slide mechanism 1032 does not prevent movement of the long-throw slide mechanism 1030. This is evident from a comparison of FIGS. 7C and 7D, in which the coarse translation plate 1042 of the long-thru slide mechanism 1030 and the fine backplate 1062 of the short-thru slide mechanism 1032 continue to translate toward the anatomical site 1.

[0138] Returning to block 1304, if there is no resistance force R to movement of head 1006 in the direction toward anatomical site 1, the method returns to block 1302 and head 1006 is further moved in the direction toward anatomical site 1 by long-range slide mechanism 1030.

[0139] 14 is a flowchart of a method of coupling a head of a medical system to an anatomical site to protect against prolonged application of initial force to the anatomical site, which may be enabled by a medical system such as the surgical system 1000 disclosed herein.

[0140] 4A and 4B, the method may be enabled by a medical system 1000 including a head 1006 having an end positioned facing a reference surface 1020 and a multi-stage slide mechanism 1008 coupled to the head. The multi-stage slide mechanism 1008 includes a coarse float mechanism 1030 and a fine float mechanism. The coarse float mechanism 1030 is configured to allow movement of the head 1006 relative to the reference surface 1020. The reference surface 1020 may correspond, for example, to a bed on which a patient having an anatomical site may lie during a surgical procedure. The fine float mechanism 1032 is configured to limit the force applied via the head 1006 to an initial force and to reduce the force applied via the head to a reduced force less than the initial force in response to the presence of a first trigger event.

[0141] Returning to FIG. 14 and further referring to FIGS. 7B and 7C, a method of coupling the head 1006 of the medical system 1000 to an anatomical site to protect against prolonged application of an initial force to the anatomical site begins at block 1402, where the head 1006 is moved relative to the anatomical site, e.g., eye 1.

[0142] At block 1404, and with further reference to FIG. 7C, the force applied by the head 1006 to the anatomical site is determined by an initial force H I As described above with reference to FIGS. 8A and 8B, this initial force H I may be set by the short-travel slide mechanism counterbalance mechanism 1066, which places the short-travel slide mechanism 1032 in heavy mode.

[0143] At block 1406, and with further reference to FIG. 7D, in response to the presence of a first trigger event, the method proceeds to block 1408, where the force applied by head 1006 to anatomical site 1 is determined as an initial force H I A reduced force H that is smaller than R The first triggering event may be the presence of a valid coupling between the cone mount 704 of the head 1006 and the patient interface 800. The reduced force HR may be set by adjusting the counterbalance mechanism 1066 of the short-throw slide mechanism 1032 to enter the light mode.

[0144] Returning to block 1406, if there is no first trigger event, the method returns to block 1404 and the force applied by head 1006 to anatomical site 1 remains limited to the initial force.

[0145] 15 is a flowchart of a method of coupling a head of a medical system to an anatomical site to further protect the anatomical site from unwanted forces. This method may be enabled by a medical system such as the surgical system 1000 disclosed herein.

[0146] 4A and 4B, the method may be enabled by a medical system 1000 including a head 1006 having an end positioned facing a reference surface 1020 and a multi-stage slide mechanism 1008 coupled to the head. The multi-stage slide mechanism 1008 includes a coarse float mechanism 1030 configured to allow movement of the head 1006 relative to the reference surface 1020. The reference surface 1020 may correspond, for example, to a surgical bed on which a patient having an anatomical site may lie during a surgical procedure. The coarse float mechanism 1030 is further configured to prevent movement of the head 1006 toward the reference surface 1020 while allowing movement of the head away from the reference surface in response to the presence of a first trigger event. Returning to FIG. 15 and further referring to FIGS. 7B and 7C, a method of coupling the head 1006 of the medical system 1000 to an anatomical site to further protect against unwanted forces on the anatomical site begins at block 1502, where the head 1006 is moved relative to the anatomical site, e.g., eye 1.

[0147] 7C, 7D, and 7E, in response to the presence of a first triggering event, at block 1504, the method proceeds to block 1506, where movement of the head 1006 toward the anatomical location is prevented while allowing movement of the head away from the anatomical location 1. To this end, the one-way brake 1039 of the coarse float mechanism 1030 is activated. The one-way brake 1039 is configured to simultaneously prevent movement of the head 1006 toward the anatomical location 1 and allow movement of the head away from the anatomical location. The first triggering event may be the presence of effective coupling between the cone mount 704 of the head 1006 and the patient interface 800 resulting from movement of the head toward the anatomical location 1 and contact with the patient interface 800, and locking of the head with the patient interface, as shown sequentially in FIGS. 7C, 7D, and 7E.

[0148] Returning to block 1504, if there is not a first trigger event, the method returns to block 1502 and head 1006 is moved further relative to anatomical site 1.

[0149] Various aspects of this disclosure are provided to enable those skilled in the art to practice the invention. Various modifications to the exemplary embodiments presented throughout this disclosure will be readily apparent to those skilled in the art. Accordingly, the claims are not intended to be limited to various aspects of this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the various components of the exemplary embodiments described throughout this disclosure that are known or later become known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be made available to the public, regardless of whether such disclosure is expressly recited in the claims. No element of a claim shall be construed under the provisions of the sixth paragraph of 35 U.S.C. § 112 unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

[0150] It is to be understood that the embodiments of the invention described herein are merely illustrative of the application of the principles of the invention, and reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims which in themselves recite features regarded as essential to the invention.

Claims

1. 1. A method of coupling a head of a medical system to an anatomical site, comprising: moving the head relative to the anatomical site; limiting the force applied by the head to the anatomical site to an initial force; and reducing the force applied by the head to the anatomical site to a reduced force less than an initial force in response to the presence of a first trigger event.

2. 10. The method of claim 1, wherein the initial force is in the range of 100 g to 300 g of weight on the anatomical site.

3. 10. The method of claim 1, wherein the reduced force is within a range of -100 g to +100 g of weight on the anatomical site.

4. The method of claim 1 , wherein moving the head relative to the anatomical site comprises moving the head toward the anatomical site with a coarse float mechanism.

5. The method of claim 1 , wherein limiting the force applied by the head to the anatomical site to an initial force comprises setting a counterbalance mechanism of a fine float mechanism to a heavy mode.

6. 6. The method of claim 5, wherein reducing the force applied by the head to the anatomical site to a reduced force less than the initial force comprises setting the counterbalance mechanism of the fine float mechanism to a light mode.

7. The method of claim 1 , further comprising detecting the presence or absence of the first trigger event.

8. the head is coupled to the anatomical location via a patient interface coupled to the anatomical location, the first trigger event corresponds to effective coupling between a cone mount of the head and the patient interface, and detecting the presence or absence of effective coupling between the cone mount and the patient interface; sensing a threshold weight or force on the patient interface; sensing a position of an outer surface of the cone mount relative to an inner surface of the patient interface; sensing a change in air pressure or air flow associated with a vacuum tube coupled to the patient interface; The method of claim 7, comprising one or more of:

9. a head having an end disposed facing a reference surface; a multi-stage slide mechanism coupled to the head, a coarse float mechanism configured to allow movement of the head relative to the reference surface; a fine float mechanism configured to limit the force applied through the head to an initial force and, in response to the presence of a first trigger event, reduce the force applied through the head to a reduced force less than the initial force; a multi-stage slide mechanism including A healthcare system with:

10. The fine float mechanism is a fine float counterbalance mechanism, balancing the weight of a load mass including the head to limit the force applied through the head to the initial force; a fine float counterbalance mechanism configured to counterbalance the weight of the payload mass including the head to limit the force applied through the head to the reduced force in response to the presence of a first trigger event. The medical system of claim 9 , comprising:

11. 11. The medical system of claim 10, wherein the fine float counterbalance mechanism comprises an adjustable spring that determines the force applied through the head.

12. The medical system of claim 10 , wherein the fine float counterbalance mechanism comprises a pneumatic device that determines the force applied through the head.

13. 11. The medical system of claim 10, wherein the fine float counterbalance mechanism comprises at least one magnetic coupling including structure arranged to provide a gap that determines the force applied through the head.

14. The structure is a pair of magnets spaced apart to define the gap; The medical system of claim 13 , comprising one of a metal plate and a magnet spaced to define the gap.

15. The structure is an intermediate fine moving magnet; a pair of metal plates; 14. The medical system of claim 13, wherein the intermediate fine movement magnet is positioned between the pair of metal plates such that the gap exists between a first surface of the intermediate fine movement magnet and at least one of the metal plates.

16. The pair of metal plates a magnetic pivot plate constructed and arranged to be repositioned relative to the first surface of the intermediate fine movement magnet, thereby changing the size of the gap; 16. The medical system of claim 15, further comprising: a fixation plate positioned against a second surface of the intermediate fine movement magnet.

17. The medical system of claim 10 , further comprising a first detection mechanism configured to detect the presence or absence of the first trigger event.

18. 18. The medical system of claim 17, wherein the head is configured to couple to an anatomical location via a patient interface coupled to the anatomical location, and the first trigger event corresponds to effective coupling between a cone mount of the head and the patient interface.

19. The first detection mechanism is a sensor configured to sense a threshold weight or force at the patient interface; a sensor configured to sense a position of an outer surface of the cone mount relative to an interior of the patient interface; a sensor configured to sense a change in air pressure or air flow associated with a vacuum tube coupled to the patient interface; 20. The medical system of claim 18, comprising at least one of:

20. a transfer arm configured to allow lateral movement of the head relative to the reference surface; 20. The medical system of claim 18, further comprising a braking system configured to transition between a locked state and an unlocked state in response to the presence or absence of the first trigger event.

21. When in a locked state, the brake system prevents at least one of lateral movement of the head via the transfer arm and movement of the head via the coarse float mechanism; 21. The medical system of claim 20, wherein when in an unlocked state, the brake system allows at least one of lateral movement of the head via the transfer arm and movement of the head via the coarse float mechanism.

22. a second detection mechanism configured to detect the presence or absence of a second trigger event corresponding to effective coupling of the patient interface to the anatomical site; 21. The medical system of claim 20, wherein the braking system is configured to transition between the locked state and the unlocked state depending on the presence or absence of the second trigger event.

23. 1. A fine float counterbalance mechanism for a medical system having a head, a cone attachment mechanism configured to secure the head to a patient interface, and an eye attachment mechanism configured to secure the patient interface to an anatomical location, wherein the fine float counterbalance mechanism is configured to set an apparent weight of a load mass including the head to one of heavy and light, and the control system: A set of sensors, a displacement sensor configured to provide a sensor signal indicative of movement of the head via a fine float mechanism; a cone-mounted sensor configured to provide a sensor signal indicative of coupling between the head and the patient interface; an eye-mounted sensor configured to provide a sensor signal indicative of coupling between the patient interface and the anatomical site; a set of sensors including one or more of: a set of operator controls configured to provide a control signal indicative of brake release; a controller comprising a variable force module coupled to the set of sensors and the set of operator controls and configured to set the apparent weight of the payload mass to one of the heavy and the light based on one or more of the sensor signals from the displacement sensor, the sensor signals from the cone-mounted sensor, the sensor signals from the eye-mounted sensor, and the control signals from the set of operator controls; A control system comprising:

24. The variable force module adjusts the apparent weight of the payload mass by: the absence of a control signal indicating brake release; a sensor signal from the cone-mounted sensor indicative of effective coupling between the head and the patient interface; a sensor signal from the eye-mounted sensor indicative of effective coupling between the patient interface and the anatomical site; 24. The control system of claim 23, configured to set the light weight in response to one or more of:

25. The variable force module adjusts the apparent weight of the payload mass by: the absence of a control signal indicating brake release; a sensor signal from the cone-mounted sensor indicative of an ineffective coupling between the head and the patient interface; a sensor signal from the eye-mounted sensor indicative of an ineffective coupling between the patient interface and the anatomical site; and 24. The control system of claim 23, configured to set the weight in response to one or more of:

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