Patent Description:
Typically, a cart is provided to support the robotic arm and allow a clinician to move the robotic arm to different locations within the operating room. The height of the robotic arm over a patient may need to be adjusted (e.g., the robotic arm is lowered or raised) to precisely position the end effector at a work site within a patient's body. Adjusting the height of the robotic arm involves moving the robotic arm vertically along a support column of the cart. Due to the weight of the robotic arm and/or other components associated with the robotic arm, manual adjustment of the vertical position of the robotic arm may require a lot of force applied either manually or by a motor.

Accordingly, solutions are sought for overcoming the challenges involved in adjusting the height of a robotic arm. In addition, there is room for improving the mechanisms used in maintaining the robotic arm at the selected height. Documents <CIT>, <CIT>, <CIT> and <CIT> disclose relevant background art.

The invention is defined in the appended independent claim <NUM>.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein:.

Embodiments of the presently disclosed robotic surgical systems including various embodiments of a robotic arm cart and methods of use thereof are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein the term "distal" refers to that portion of the robotic surgical system or component thereof, that is closer to the patient, while the term "proximal" refers to that portion of the robotic surgical system or component thereof, that is farther from the patient.

As will be described in detail below, provided are embodiments of a surgical cart for supporting a robotic arm and for facilitating movement of the robotic arm around an operating room. The cart includes a base equipped with wheels, and a support column extending vertically from the base. The support column supports a carriage that is movable along the vertical axis of the support column and which carries a robotic arm. The surgical cart further includes a counterbalance mechanism that functions to assist a clinician in manually adjusting the vertical position of the carriage along the support column. Further provided by the present disclosure is a braking mechanism that maintains the selected vertical position of the carriage relative to the support column.

Referring initially to <FIG>, a surgical system, such as, for example, a robotic surgical system <NUM> is shown. In embodiments, robotic surgical system <NUM> is located in an operating room "OR" Robotic surgical system <NUM> generally includes a plurality of surgical robotic arms <NUM>, <NUM> having a surgical instrument, such as, for example, an electromechanical instrument <NUM> removably attached thereto; a control device <NUM>; and an operating console <NUM> coupled with control device <NUM>.

Operating console <NUM> includes a display device <NUM>, which is set up in particular to display three-dimensional images; and manual input devices <NUM>, <NUM>, by means of which a person (not shown), e.g., a clinician, is able to telemanipulate robotic arms <NUM>, <NUM> in a first operating mode, as known in principle to a person skilled in the art. Each of the robotic arms <NUM>, <NUM> may be composed of a plurality of members, which are connected through joints.

Robotic arms <NUM>, <NUM> may be driven by electric drives (not shown) that are connected to control device <NUM>. Control device <NUM> (e.g., a computer) is set up to activate the drives, in particular by means of a computer program, in such a way that robotic arms <NUM>, <NUM> and thus electromechanical instrument <NUM> (including the electromechanical end effector (not shown)) execute a desired movement according to a movement defined by means of manual input devices <NUM>, <NUM>. Control device <NUM> may also be set up in such a way that it regulates the movement of robotic arms <NUM>, <NUM> and/or of the drives.

Robotic surgical system <NUM> is configured for use on a patient "P" lying on a surgical table "ST" to be treated in a minimally invasive manner by means of a surgical instrument, e.g., electromechanical instrument <NUM>. Robotic surgical system <NUM> may also include more or less than two robotic arms <NUM>, <NUM>, the additional robotic arms likewise being connected to control device <NUM> and being telemanipulatable by means of operating console <NUM>. A surgical instrument, for example, electromechanical instrument <NUM> (including the electromechanical end effector), may also be attached to the additional robotic arm.

The robotic arms, such as for example, robotic arm <NUM>, is supported on a surgical cart <NUM>. The surgical cart <NUM> may incorporate the control device <NUM>. In embodiments, the robotic arms, such as for example, robotic arm <NUM> may be coupled to the surgical table "ST.

For a detailed discussion of the construction and operation of a robotic surgical system, reference may be made to <CIT>, entitled "Medical Workstation.

With reference to <FIG>, one exemplary embodiment of a surgical cart of robotic surgical system <NUM>, configured for use in accordance with the present disclosure, is shown generally using reference numeral <NUM>. The surgical cart <NUM> is configured to move robotic arm <NUM> (<FIG>) to a selected position within operating room "OR" (<FIG>) and to provide height adjustment of the robotic arm <NUM>. The surgical cart <NUM> generally includes a cart base <NUM>, a support column <NUM> extending vertically (i.e., perpendicularly) from the cart base <NUM>, and a carriage or slider <NUM> slidably supported on column <NUM> and configured for supporting robotic arm <NUM> thereon.

The support column <NUM> of the surgical cart <NUM> defines a longitudinal axis "X" and has a first end 104a supported on the cart base <NUM> and a second free end 104b. The support column <NUM> includes a pair of opposed sidewalls 108a, 108b. A pair of handles 110a, 110b is attached to respective sidewalls 108a, 108b and is configured to be grasped by a clinician to facilitate movement of the surgical cart <NUM> within the operating room "OR. " The sidewalls 108a, 108b of the support column <NUM> are laterally spaced from one another to define a longitudinally-extending channel <NUM> having an internal support structure <NUM> disposed therein.

With reference to <FIG> and <FIG>, the internal support structure <NUM> of the support column <NUM> extends along the longitudinal axis "X" of the support column <NUM> and is configured to slidably support both the carriage <NUM> and a counterweight <NUM>. In particular, the internal support structure <NUM> of the support column <NUM> has a first longitudinal side 114a defining a first longitudinally-extending track 116a, and a second longitudinal side 114b defining a second longitudinally-extending track 116b. The carriage <NUM> is slidably supported in the first track 116a of the first longitudinal side 114a, and the counterweight <NUM> is slidably supported in the second track 116b of the second longitudinal side 114b. The support column <NUM> includes a platform <NUM> disposed on the internal support structure <NUM>, at second free end 104b of column <NUM>, for supporting a pulley assembly <NUM> thereon.

With reference to <FIG> and <FIG>, surgical cart <NUM> includes the pulley assembly which mechanically joins the carriage <NUM> with the counterweight <NUM>. The pulley assembly <NUM> includes a first pair of pulleys 120a and a second pair of pulleys 120b each supported on and fixed to the platform <NUM> of the support column <NUM>. The first and second pairs of pulleys 120a, 120b are spaced laterally from one another such that the first pair of pulleys 120a is disposed adjacent the first sidewall 108a (<FIG>) of the support column <NUM>, and the second pair of pulleys 120b is disposed adjacent the second sidewall 108b (<FIG>) of the support column <NUM>. It is contemplated that the pulley assembly <NUM> may include first and second solitary pulleys instead of first and second pairs of pulleys.

The pulleys 120a, 120b are rotatably supported on platform <NUM> via respective hubs 122a, 122b. It is contemplated that each of the hubs 122a, 122b may include a braking mechanism <NUM>, such as, for example, a servomotor brake or an electromagnetic brake, configured to selectively halt rotation of the pulleys 120a, 120b. In embodiments, the hubs 122a, 122b may each include a motor <NUM> for driving a rotation of the pulleys 120a, 120b, thereby moving the carriage <NUM>. A detailed description of an exemplary servomotor brake may be found in <CIT>. In embodiments, the pulleys 120a, 120b may have an absolute encoder to determine a position of the robotic arm <NUM>.

With reference to <FIG> and <FIG> and according to the invention, the pulley assembly <NUM> includes first and second cables <NUM>, <NUM> and a toggle bar <NUM>. The first cable <NUM> extends over the first pair of pulleys 120a, and the second cable <NUM> extends over the second pair of pulleys 120b. The first cable <NUM> has a first end 128a fixedly coupled to the counterweight <NUM>, and a second end (not explicitly shown) fixedly coupled to the carriage <NUM>. Similarly, the second cable <NUM> has a first end (not explicitly shown) fixedly coupled to the counterweight <NUM>, and a second end (not explicitly shown) fixedly coupled to the carriage <NUM>.

The toggle bar <NUM> of the pulley assembly <NUM> is pivotably supported on the counterweight <NUM>. The toggle bar <NUM> has a first end 134a having the first end 128a of the first cable <NUM> fixed thereto, and a second end 134b having the first end of the second cable <NUM> fixed thereto. The toggle bar <NUM> has an intermediate portion pivotably attached to a fulcrum <NUM>, which is attached to the counterweight <NUM>.

The toggle bar <NUM> accounts for any manufacturing tolerances or stretching in the cables <NUM>, <NUM> that may occur over time. For example, if the first cable <NUM> begins to stretch or lengthen whereas the second cable <NUM> does not, the toggle bar <NUM> will pivot to move the first end 134a of the toggle bar <NUM> toward the counterweight <NUM> to account for the lengthening of the first cable <NUM>. As such, even with an uneven tension in one of the cables <NUM>, <NUM>, the first and second cables <NUM>, <NUM> continue to carry an equal load of the counterweight <NUM>. Further, the toggle bar <NUM> accommodates for manufacturing tolerances in the cables 128a, <NUM>.

With reference to <FIG>, the counterweight <NUM> has a mass substantially equal to the combined mass of the carriage <NUM>, the robotic arm <NUM>, and the attached surgical instrument <NUM>. In some embodiments, the counterweight <NUM> may have a mass substantially equal to the combined mass of the carriage <NUM>, the robotic arm <NUM>, and/or the surgical instrument <NUM>. The counterweight <NUM> functions to reduce the effort required of a clinician, or in some embodiments, a motor, in raising or lowering the carriage <NUM> (with the robotic arm <NUM> attached) along the support column <NUM> by making the carriage <NUM> free-floating. As illustrated, the counterweight <NUM> may include a plurality of discreet weights stacked on one another. Each of the weights may be detachable from the counterweight unit <NUM> to provide a clinician with the ability to adjust the mass of the counterweight <NUM> depending on the mass of the carriage <NUM>, the robotic arm <NUM>, and/or other components being ultimately supported by the carriage <NUM>. In embodiments, the counterweight <NUM> may be considered a component of the pulley assembly <NUM>.

With reference to <FIG> and <FIG>, the surgical cart <NUM> includes a braking mechanism <NUM> disposed within the cavity <NUM> of the support column <NUM>. The braking mechanism <NUM> includes a shaft or rod <NUM> and a brake <NUM> slidably mounted to the shaft <NUM>. The shaft <NUM> extends longitudinally within the support column <NUM> and is fixed at its ends between the platform <NUM> and the cart base <NUM>.

The brake <NUM> has a connector or extension <NUM> that fixes the brake <NUM> to the carriage <NUM> such that axial movement of the carriage <NUM> along the track 116a of the support column <NUM> causes the brake <NUM> to slide along the shaft <NUM>. A longitudinally-extending channel <NUM> is defined through the brake <NUM> and has the shaft <NUM> extending therethrough. The brake <NUM> may be configured as an electromagnetic brake, a servomotor brake, hydraulic, pneumatic, or the like.

In response to an actuation of the brake <NUM> via the control device <NUM>, the brake <NUM> frictionally engages the shaft <NUM>. In some embodiments, instead of or in addition to the control device <NUM> being responsible for actuating the brake <NUM>, the brake <NUM> may include a sensor (not explicitly shown) that senses a threshold force applied on the carriage <NUM> causing the brake <NUM> to automatically release from engagement with the shaft <NUM>. The threshold force sensed by the sensor may be an upward force applied by the clinician on the carriage <NUM> intended to raise the carriage <NUM>. In embodiments, the brake <NUM> may automatically frictionally engage the shaft <NUM> in the absence of the threshold force.

In other embodiments, the sensor may be configured to detect when the motor <NUM> (<FIG>) of the pulley assembly <NUM> is being activated, or may receive a contemporaneous signal from control device <NUM> indicating that motor <NUM> is being activated. Upon the sensor sensing an activation of the motor <NUM> or receiving a signal from control device <NUM>, the brake <NUM> releases from engagement with the shaft <NUM> to allow for the raising or lowering of the carriage <NUM> driven by the motor <NUM>.

With reference to <FIG>, the cart base <NUM> of the surgical cart <NUM> is fixed to the first end 104a of the support column <NUM> and includes four casters 103a, 103b, 103c, 103d. In some embodiments, the cart base <NUM> may include more or less than four casters. The cart base <NUM> further includes two foot pedals 105a, 105b coupled to the casters 103a-103d via linkages 107a, 107b that function to rotate the casters 103a-103d in a selected direction. As such, using the foot pedals 105a, 105b, a clinician may control the direction of movement of the surgical cart <NUM>.

In operation, with a robotic arm <NUM> supported on the carriage <NUM>, the carriage <NUM> may be raised or lowered to a selected vertical position along the longitudinal axis "X" of the support column <NUM>. For example, to raise the carriage <NUM>, and in turn the robotic arm <NUM>, a clinician may either actuate the motor <NUM> in the hubs 122a, 122b of the pulley assembly <NUM> via the control device <NUM>, or manually raise the carriage <NUM> by hand. In either scenario, the counterweight <NUM> of the pulley assembly <NUM> reduces the energy or force required to raise the carriage <NUM> due to the counterweight <NUM> acting on the carriage <NUM> in the same direction that the carriage <NUM> is being moved by the clinician or the motor <NUM>.

Upon the clinician ceasing application of the upward force on the carriage <NUM>, the brake <NUM> of the braking mechanism <NUM> automatically (e.g., via the sensor) frictionally engages the shaft <NUM> of the braking mechanism <NUM>, thereby halting further vertical movement, in either direction, of the carriage <NUM> along the support column <NUM>. Similarly, in the scenario where the motor <NUM> of the pulley assembly <NUM> is used to adjust the height of the carriage <NUM>, upon the motor <NUM> ceasing to rotate the pulleys 120a, 120b, the brake <NUM> of the braking mechanism <NUM> is automatically actuated (e.g., via the sensor) to engage the shaft <NUM> of the braking mechanism <NUM>, thereby halting further vertical movement of the carriage <NUM> along the support column <NUM> in either direction. In embodiments, the brake <NUM> may have a manual override in case of a power failure.

With the brake <NUM> engaged to the shaft <NUM>, the carriage <NUM> will be fixed in its vertical position on the support column <NUM>. In the instance where the combined mass of the carriage <NUM>, the robotic arm <NUM>, and the surgical instrument <NUM> is greater than the mass of the counterweight <NUM>, the brake <NUM> will prevent the carriage <NUM> from being lowered so long as the brake <NUM> is in the actuated state. In the alternative instance where the counterweight <NUM> is greater in mass than the combined mass of the carriage <NUM>, the robotic arm <NUM>, and the surgical instrument <NUM>, the brake <NUM> will prevent the carriage <NUM> from being raised so long as the brake <NUM> is in the actuated state.

With reference to <FIG> and <FIG>, illustrated is another embodiment of a surgical cart <NUM> of the robotic surgical system <NUM> configured for use in accordance with the present disclosure. The surgical cart <NUM> is configured to move the robotic arm <NUM> to a selected position within operating room "OR" (<FIG>) and to provide vertical movement of the robotic arm <NUM>. The surgical cart <NUM> generally includes a cart base <NUM>, a support column <NUM> extending vertically (e.g., perpendicularly) from the cart base <NUM>, and a carriage or slider <NUM> configured for supporting the robotic arm <NUM> thereon. Only those components of the surgical cart <NUM> deemed important in elucidating features that differ from the surgical cart <NUM> of <FIG> will be described in detail.

The surgical cart <NUM> includes a braking mechanism <NUM> for selectively fixing the vertical position of the carriage <NUM>, and in turn the robotic arm <NUM>, relative to the support column <NUM>. In one embodiment, the braking mechanism <NUM> includes a ball screw assembly <NUM>, <NUM> and a motorized brake <NUM> operably engaged to the ball screw assembly. The ball screw assembly includes a ball screw <NUM> and a ball nut <NUM> threadingly coupled to the ball screw <NUM>. In embodiments, instead of the braking mechanism <NUM> having a ball screw assembly, the braking mechanism <NUM> may include a conventional lead screw and a conventional nut threaded thereto. The ball screw <NUM> has a high pitch relative to a conventional ball screw, wherein the relative high pitch facilitates raising and lowereing of carriage <NUM>, and in turn, robotic arm <NUM>.

The ball nut <NUM> of the braking mechanism <NUM> is rotatably mounted to the carriage <NUM> such that the nut <NUM> moves with the carriage <NUM> axially along the length of the support column <NUM>. It is contemplated that the nut <NUM> may have a surface feature (not explicitly shown) defined on its outer surface that engages with a corresponding surface feature (not explicitly shown) on the carriage <NUM> which allows for relative rotation of the nut <NUM> while inhibiting relative axial movement of the nut <NUM>. The nut <NUM> is threadingly coupled to the ball screw <NUM> such that axial movement of the nut <NUM> along the ball screw <NUM> causes the ball screw <NUM> to rotate about its longitudinal axis. The ball screw <NUM> of the braking mechanism <NUM> extends longitudinally within the support column <NUM> and is axially fixed at its ends between a platform <NUM> and the brake <NUM> of the braking mechanism <NUM>.

The brake <NUM> of the braking mechanism <NUM> is mounted on the end of the ball screw <NUM> and may be an electromagnetic brake, a servomotor brake, or the like. The brake <NUM> defines a longitudinally-extending channel <NUM> having the end of the ball screw <NUM> extending therethrough. The brake <NUM> is configured to selectively frictionally engage the ball screw <NUM> in response to an actuation of the brake <NUM> via the control device <NUM>. In some embodiments, instead of or in addition to the control device <NUM> being responsible for actuating the brake <NUM>, the brake <NUM> may include a sensor (not explicitly shown) that controls the actuation of the brake <NUM>. In particular, the sensor may be configured to sense a threshold force applied on the carriage <NUM> and in response cause the brake <NUM> to automatically release from engagement with the ball screw <NUM>. The threshold force sensed by the sensor may be caused by a clinician applying an upward force on the carriage <NUM> intended to raise the carriage <NUM>. The brake <NUM> may be further configured to automatically frictionally engage the ball screw <NUM> in the absence of the threshold force. As such, the sensor controls the brake <NUM> of the braking mechanism <NUM> for selectively fixing the vertical position of the carriage <NUM> on the support column <NUM>. As can be appreciated, a processor (not explicitly shown) may be provided to direct the operation of the brake <NUM> in response to the sensor sensing the threshold force.

In some embodiments, the surgical cart <NUM> may further include a motor <NUM> operably coupled to the ball screw <NUM> to effect a rotation of the ball screw <NUM>. In this embodiment, an activation of the motor <NUM> causes the ball screw <NUM> to rotate, thereby driving an upward or downward movement of the nut <NUM> along the ball screw <NUM> and, in turn, a corresponding upward or downward movement of the carriage <NUM>. In other embodiments, the sensor may be configured to detect when the motor <NUM> is being activated and upon the sensor sensing the activation of the motor <NUM>, the brake <NUM> may be configured to automatically release from engagement with the ball screw <NUM> to allow for the raising or lowering of the carriage <NUM> by the motor <NUM>. In still other embodiments, another brake (not shown) may be provided that selectively engages the nut <NUM> to prevent rotation of the nut <NUM> and/or axial translation of the nut <NUM>.

In operation, to raise or lower the robotic arm <NUM>, a clinician may either manually apply a force on the carriage <NUM>, or the motor <NUM> may be activated by a clinician pressing a button to drive the carriage <NUM> movement. The sensor senses either the manual force being applied on the carriage <NUM>, or the sensor senses an activation of the motor <NUM>. The sensor communicates with the processor, which then directs the brake <NUM> of the braking mechanism <NUM> to release the ball screw <NUM>. If vertical adjustment of the carriage <NUM> is being driven manually, the force applied on the carriage <NUM> by the clinician moves the carriage <NUM> and the attached nut <NUM> and robotic arm <NUM>, along the ball screw <NUM> since the ball screw <NUM> is no longer being prevented from rotating by the brake <NUM>. If vertical adjustment of the carriage <NUM> is being driven by the motor <NUM>, the activation of the motor <NUM> rotates the ball screw <NUM> since the ball screw <NUM> is no longer being prevented from rotating by the brake <NUM>. As the ball screw <NUM> rotates, the nut <NUM> moves along the ball screw <NUM>, thereby moving the carriage <NUM> and the attached robotic arm <NUM> along the support column <NUM>.

With reference to <FIG> and <FIG>, illustrated is another embodiment of a braking mechanism <NUM> for use with the surgical cart <NUM> of the robotic surgical system <NUM>. The braking mechanism <NUM> includes a linear motion brake mounted to the carriage <NUM> and movable therewith. The linear motion brake includes a pair of clamp arms 262a, 262b that selectively grasp a track <NUM> of the support column <NUM> to halt axial movement of the carriage <NUM> along the track <NUM>. The linear motion brake may include a manual actuator <NUM> operable by a clinician to manually actuate the linear brake. A detail description of an exemplary linear motion brake may be found in <CIT>.

With reference to <FIG>, illustrated is another embodiment of a surgical cart <NUM> of robotic surgical system <NUM> configured for use in accordance with the present disclosure. The surgical cart <NUM> is configured to move the robotic arm <NUM> to a selected position within the operating room "OR" (<FIG>) and to provide vertical movement of the robotic arm <NUM>. The surgical cart <NUM> generally includes a cart base <NUM>, a support column <NUM> extending vertically (e.g., perpendicularly) from the cart base <NUM>, and a carriage or slider <NUM> configured for supporting the robotic arm <NUM> thereon. Only those components of the surgical cart <NUM> deemed important in elucidating features that differ from the surgical cart <NUM> of <FIG> will be described in detail.

The surgical cart <NUM> includes a braking mechanism <NUM>, similar to the braking mechanism <NUM> described with reference to <FIG>. The braking mechanism <NUM> is configured to fix the vertical position of the carriage <NUM>, and in turn the robotic arm <NUM>, relative to the support column <NUM>. The braking mechanism <NUM> includes a rack <NUM> and pinion <NUM> operably coupled to one another to selectively halt axial movement of the carriage <NUM> along the support column <NUM>.

The rack <NUM> of the braking mechanism <NUM> is fixedly mounted to the support column <NUM> and extends parallel with the longitudinal axis of the support column <NUM>. The rack <NUM> defines a plurality of teeth <NUM> along its length configured to meshingly engage with bars <NUM> of the pinion <NUM>. The pinion <NUM> of the braking mechanism <NUM> is non-rotatably mounted to an axle <NUM> that is rotatably mounted to the carriage <NUM>. As such, the pinion <NUM> is able to rotate relative to the carriage <NUM> while being axially fixed relative to the carriage <NUM>. In some embodiments, the axle <NUM> is rotatably fixed relative to the carriage <NUM> while the pinion <NUM> is rotatably mounted to the axle <NUM>. In some embodiments, the pinion <NUM> may have helical teeth for reducing backlash.

The braking mechanism <NUM> further includes a brake <NUM> mounted to an end of the axle <NUM>. The brake <NUM> may be an electromagnetic brake, a servomotor brake, or the like, and is configured to selectively frictionally engage the pinion <NUM> in response to an actuation of the brake <NUM> via the control device <NUM>. In some embodiments, instead of or in addition to the control device <NUM> being responsible for actuating the brake, the brake <NUM> may include a sensor (not explicitly shown) that controls the actuation of the brake <NUM>. In particular, the sensor may be configured to sense a threshold force applied on the carriage <NUM> and in response cause the brake <NUM> to automatically release from engagement with the pinion <NUM>. The threshold force sensed by the sensor may be caused by a clinician applying an upward force on the carriage <NUM> intended to raise the carriage <NUM>. The brake <NUM> may be further configured to automatically frictionally engage the pinion <NUM> in the absence of the threshold force. As such, the sensor controls the brake <NUM> of the braking mechanism <NUM> for selectively fixing the vertical position of the carriage <NUM> on the support column <NUM>. As can be appreciated, a processor, e.g., the control device <NUM>, may be provided to direct the operation of the brake <NUM> in response to the sensor sensing the threshold force.

The support column <NUM> may further include a motor (not explicitly shown) operably coupled to the pinion <NUM> or the axle <NUM> to effect a rotation of the pinion <NUM> either directly, or indirectly via the axle <NUM>. In this embodiment, an activation of the motor causes the pinion <NUM> to rotate, thereby driving an upward or downward movement of the pinion <NUM> along the rack <NUM>, and in turn, a corresponding upward or downward movement of the carriage <NUM> along the support column <NUM>. In other embodiments, the sensor may be configured to detect when the motor is being activated and upon the sensor sensing an activation of the motor, the brake <NUM> may automatically release from engagement with the pinion <NUM> to allow for the raising or lowering of the carriage <NUM>. As can be appreciated, the processor may be configured to direct the operation of the brake <NUM> in response to the sensor sensing an activation or deactivation of the motor.

In one embodiment, both the axle <NUM> and the pinion <NUM> may be non-rotatable relative to the carriage <NUM>. In this embodiment, the pinion <NUM> is movable between a first or braking position in which the pinion <NUM> is engaged to the rack <NUM>, and a second or non-braking position in which the pinion <NUM> is disengaged from the rack <NUM>. As such, the pinion <NUM> acts as the brake <NUM> by being selectively engaged with the rack <NUM> to halt movement of the carriage <NUM> along the support column <NUM>.

In operation, to raise or lower the robotic arm <NUM>, a clinician may either manually apply a force on the carriage <NUM>, or the motor may be activated to drive the carriage <NUM> movement. The sensor senses either the manual force being applied on the carriage <NUM> by the clinician, or the sensor senses an activation of the motor. The sensor communicates with the processor, which then directs the brake <NUM> of the braking mechanism <NUM> to release the pinion <NUM>. If vertical adjustment of the carriage <NUM> is being driven manually, the force applied on the carriage <NUM> by the clinician moves the carriage <NUM>, the attached robotic arm <NUM>, and the pinion <NUM>, along the support column <NUM> since the pinion <NUM> is no longer being prevented from rotating by the brake <NUM>. If vertical adjustment of the carriage <NUM> is being driven by the motor, the activation of the motor rotates the pinion <NUM> since the pinion <NUM> is no longer being prevented from rotating by the brake <NUM>. As the pinion <NUM> rotates, the pinion <NUM> moves axially along the rack <NUM>, thereby moving the carriage <NUM> and the attached robotic arm <NUM> along the support column <NUM>.

With reference to <FIG>, the surgical cart <NUM> includes a pair of spring members 320a, 320b mounted in the support column <NUM> and configured to counterbalance the combined mass of the carriage <NUM> and the attached robotic arm <NUM>. Each of the spring members 320a, 320b may be constant force springs having one or more laminations or layers fabricated from stainless steel, fiberglass, or any suitable material. The number and thickness of the laminations and the type of material used to fabricate the constant-force springs 320a, 320b is selected based on the combined mass of the carriage <NUM>, the robotic arm <NUM>, and the attached surgical instrument.

The constant-force springs 320a, 320b are each coiled about a drum 322a, 322b. The two drums 322a, 322b are disposed adjacent one another and are each rotatably mounted to a respective axle or pivot pin 324a, 324b. A first end of each of the springs is secured (e.g., bolted or soldered) to the respective drum 322a, 322b, and a second end <NUM>, <NUM> of each of the springs 320a, 320b extends downwardly from the respective drum 322a, 322b. One or both of the second ends <NUM>, <NUM> of the springs 320a, 320b are directly attached to the carriage <NUM>. The springs 320a, 320b function to reduce the effort required of a clinician, or in some embodiments, a motor, in raising or lowering the carriage <NUM> (with the robotic arm <NUM> attached) along the support column <NUM> by making the carriage <NUM> free-floating. As shown in <FIG> and <FIG>, electrical switches <NUM>, such as, for example, hall effect sensors, may be associated with the springs 320a, 320b used to detect if the springs 320a, 320b break. Specifically, if and spring 320a, 320b should break, the respective electrical switch <NUM> would be activated, thereby providing a signal or the like to the clinician or technician that there has been a failure, and, in embodiments, the system is placed in a permanent or temporary "hold" or "shut-down" state, until the particular robotic cart <NUM> is replaced and/or repaired.

In operation, with a robotic arm <NUM> supported on the carriage <NUM>, the carriage <NUM> may be raised or lowered to a selected position along the longitudinal axis of the support column <NUM>. For example, to lower the carriage <NUM>, a threshold amount of force is required to overcome the spring force of the springs 320a, 320b. Upon overcoming the spring force of the springs 320a, 320b, the carriage <NUM> is lowered away from the drums 322a, 322b, thereby uncoiling the springs 320a, 320b. A brake, such as, for example, the braking mechanism <NUM>, may be used to maintain the carriage <NUM> in the selected vertical position on the support column <NUM>.

To raise the carriage <NUM> from the lowered position, the brake is released allowing the spring force of the springs 320a, 320b to act on the carriage <NUM>. As the springs 320a, 320b attempt to return to their natural, coiled state, the springs 320a, 320b exert an upwardly-oriented force on the carriage <NUM> to facilitate upward vertical movement of the carriage <NUM> along the support column <NUM>. As such, the springs 320a, 320b reduce the energy required to raise the carriage <NUM> due to the springs 320a, 320b acting on the carriage <NUM> in the same direction the carriage <NUM> is being moved by the clinician or the motor.

With continued reference to <FIG>, the cart <NUM> may further include an overlatch mechanism for adjusting the force required to rotate the pinion <NUM> of the braking mechanism <NUM>. In particular, the overlatch mechanism includes a cable <NUM>, a lever <NUM>, and a pivot arm <NUM> (<FIG>). The cable <NUM> has a first end 330a anchored to the lever <NUM>, and a second end 330b anchored to a base of the support column <NUM>. The cable <NUM> is wrapped about the pinion <NUM> of the braking mechanism <NUM> to provide a selective amount of resistance to rotation of the pinion <NUM>. For example, the tighter the cable <NUM> is wrapped about pinion <NUM>, the more force is required to rotate pinion <NUM> and, in turn, move the carriage <NUM> along the axis of the support column <NUM>. To lower the tension in the cable <NUM>, the lever <NUM> is actuated, which causes the pivot arm <NUM> to pivot downwardly, thereby bringing the first end 330a of the cable <NUM> closer to the second end 330b. In this way, the cable <NUM> loosens about the pinion <NUM> to allow the pinion <NUM> to more easily rotate.

It is contemplated that the surgical carts <NUM>, <NUM>, <NUM> of the present disclosure may incorporate any of the braking mechanisms described above for holding the carriage in a selected vertical position along the support column.

Claim 1:
A surgical cart (<NUM>) for supporting a robotic arm (<NUM>), comprising:
a vertically-extending support column (<NUM>) defining a longitudinal axis;
a carriage (<NUM>) movably coupled to the support column and configured to carry a robotic arm; and
a braking mechanism (<NUM>) including:
a rack (<NUM>) fixed to the support column; and
a pinion (<NUM>) mounted to the carriage and configured to operably couple to the rack such that axial movement of the carriage along the longitudinal axis defined by the support column is prevented in response to a ceasing of rotation of the pinion wherein the braking mechanism includes a brake (<NUM>) coupled to the pinion and configured to move relative to the pinion between a first position in which the pinion is permitted to rotate, and a second position, in which the brake prevents the pinion from rotating relative to the brake; or
wherein the pinion is non-rotatably coupled to the carriage and is selectively movable relative to the rack between a first or braking position in which the pinion is operably coupled to the rack, and a second or non-braking position in which the pinion is disengaged from the rack;
the cart further comprising a pulley assembly (<NUM>) including:
a first pulley (120a) supported on the support column;
a first cable (<NUM>) extending over the first pulley and having a first end fixed to the carriage and a second end; and
a counter weight (<NUM>) fixed to the second end of the first cable,
a second pulley (120b) supported on the support column;
a second cable (<NUM>) extending over the second pulley and having a first end fixed to the carriage and a second end fixed to the counterweight; and
wherein the pulley assembly includes a toggle bar (<NUM>) pivotably coupled to the counterweight, the toggle bar including a first end (134a) having the second end of the first cable fixed thereto, and a second end (134b) having the second end of the second cable fixed thereto.