Patent Description:
Concentric-tube robots (CTRs) can be used for performing surgical procedures. The CTR has telescopic tubes that are concentric and can rotate and translate reciprocally. Motion is transmitted between the robotic actuators and the surgical instrument. Sterility is a requirement of the surgical environment.

<CIT> discloses a modular sterilisable robotic system for endonasal surgery. Robotic tool cassettes, each including a concentric-tube manipulator, are configured to interchangeably connect with mounting structures of the surgical robot system. The tool cassettes are sterilisable. However, there is no sterile access to the inner channel of the robotic instrument that could be used for, for example, suction or irrigation in surgical applications.

<CIT> discloses a catheter driver system. Other relevant prior art can be found in <CIT>, <CIT>, and <CIT>.

It is an aim of the present disclosure to provide an actuation system which meets the sterility requirements of the surgical environment.

According to the invention there is provided a robot as defined in claim <NUM>.

<FIG> schematically shows an actuation system <NUM> according to an embodiment of the invention. The actuation system <NUM> is for actuating a tool <NUM>, comprising at least one tube <NUM>, of a robot such as a concentric-tube robot (CTR). As shown in <FIG>, the actuation system <NUM> comprises an actuation unit <NUM>. The main purpose of the actuation unit <NUM> is to carry all the motors and electronics needed to run the robot. As shown in <FIG> and explained in further detail below, the actuation unit <NUM> comprises actuation mechanisms <NUM>, <NUM>. Optionally, the actuation unit <NUM> is reusable. Typically, the actuation unit <NUM> is not sterilised. Typically, the actuation unit <NUM> is cleaned with wipes or cloths, for example.

As shown in <FIG>, optionally the actuation system <NUM> comprises a drape sleeve <NUM>. The drape sleeve <NUM> is configured to cover the actuation unit <NUM>. The actuation unit <NUM> can be inserted into the drape sleeve <NUM>. The drape sleeve <NUM> can help to allow the actuation unit <NUM> to be used in a sterile surgical environment.

As shown in <FIG>, the actuation system <NUM> comprises a plate interface <NUM>. The plate interface <NUM> allows motion to be transmitted between the non-sterile actuation unit <NUM> and a sterile tool <NUM> of the robot. The plate interface <NUM> is configured to separate the non-sterile actuation unit <NUM> from the sterile instrument.

Optionally, the plate interface <NUM> is attachable to and detachable from the actuation unit <NUM>. For example, the plate interface <NUM> may be mounted once per surgical operation.

The invention will be described below in the context of an example in which the tool <NUM> comprises a plurality of concentric tubes <NUM>, although it will be understood that the tool <NUM> may comprise only one tube <NUM>. As shown in <FIG>, optionally the plate interface <NUM> is for supporting the concentric tubes <NUM> such that the concentric tubes <NUM> can be removed from and replaced on the plate interface <NUM>. Multiple tools <NUM> (i.e. sterile instruments) can be exchanged during the same surgical operation. Optionally, the tools <NUM> are disposable.

As shown in <FIG>, the actuation system <NUM> is configured to actuate the concentric tubes <NUM> from radially to one side of the concentric tubes <NUM>. For example, as shown in <FIG>, the concentric tubes <NUM> of the tool <NUM> may be mounted on the top of the actuation system <NUM>. The concentric tubes <NUM> define an axial direction. The actuation unit <NUM> that comprises the motors is radially beside (below in the orientation shown in <FIG>) the concentric tubes <NUM>. This arrangement is different from prior art systems in which the actuation unit is typically positioned directly behind the concentric tubes <NUM>. The actuation unit in the prior art systems is typically in the same axis as the axis defined by the concentric tubes.

By providing that the concentric tubes <NUM> are actuated from radially to one side of the concentric tubes <NUM>, the position directly behind the concentric tubes <NUM> can remain sterile. This keeps the tip <NUM> of the tool <NUM> in the sterile environment. This also allows sterile access to the inner channel <NUM> (see, for example, <FIG>) of the robotic tool <NUM> (i.e. inside the tubes <NUM>). Such sterile access is described in further detail below and with reference to <FIG>. In contrast, prior art systems have their access to the inner channel blocked by the actuation unit which is not sterilisable.

In <FIG>, the tool <NUM> is shown positioned on top of the actuation unit <NUM>. However, the orientation between the CTR <NUM> and the actuation unit <NUM> is not particularly limited. For example, the tool <NUM> may alternatively be positioned to one side of the actuation unit <NUM>. In a further alternative, the tool <NUM> may be positioned below the actuation unit <NUM>. The actuation unit <NUM> is not positioned behind the concentric tubes <NUM> along the axis defined by the concentric tubes <NUM>.

As shown in <FIG>, the tool <NUM> comprises a tip <NUM>. The tip <NUM> may comprise an end effector <NUM> (see, for example, <FIG>). The end effector <NUM> may be a surgical instrument for performing a surgical operation (or part of a surgical operation). The tip <NUM> may be connected to the inner concentric tube 21c. The movement of the tip <NUM> is controlled by controlling the rotation of the concentric tubes <NUM> and the axial translation of the concentric tubes <NUM> relative to each other. Optionally, the tool <NUM> comprises a plurality of concentric tubes <NUM>. For example, the tool <NUM> may comprise three tubes <NUM>. Alternatively the tool <NUM> may comprise four or more tubes <NUM>. The concentric tubes <NUM> may comprise an inner tube 21c, an intermediate tube 21b and an outer tube 21a. As a further alternative, the tool <NUM> may comprise only one tube <NUM>.

The actuation mechanisms <NUM>, <NUM> of the actuation unit <NUM> are configured to control the movement of the tip <NUM> by controlling the rotational and translational movements of the concentric tubes <NUM> of the tool <NUM>.

As shown in <FIG>, the area directly behind the concentric tubes <NUM> is on the opposite side of the drape sleeve <NUM> from the actuation unit <NUM>. Hence, this region may be part of the sterile surgical environment. The region directly behind the concentric tubes <NUM> is separated from the actuation unit <NUM>.

<FIG> is a schematic view of the actuation system <NUM> shown in <FIG>. In the view shown in <FIG>, the tool <NUM> is removed. As shown in <FIG>, the plate interface <NUM> may be mounted on the actuation unit <NUM>. As shown in <FIG>, the drape sleeve <NUM> is sandwiched between the plate interface <NUM> and the actuation unit <NUM> when the plate interface <NUM> is attached to the actuation unit <NUM>. Of course, when the plate interface <NUM> is detached from the actuation unit <NUM>, the drape sleeve <NUM> is no longer sandwiched. Optionally, the drape sleeve <NUM> is directly attached to the plate interface <NUM> even when the plate interface <NUM> is not attached to the actuation unit <NUM>. The drape sleeve <NUM> may comprise a window corresponding to the shape of the plate interface <NUM> so as to allow the plate interface <NUM> to be attached to the actuation unit <NUM> without interference from the drape sleeve <NUM>.

A method of using the actuation system <NUM> in a surgical application is described below. Optionally, a kit of parts is provided. The kit of parts comprises the actuation unit <NUM>, the plate interface <NUM> and the drape sleeve <NUM>. The plate interface <NUM> may be packaged in sterile packaging so as to keep it sterile from the actuation unit <NUM>. The parts may be covered by a dust cover, for example.

First, the dust cover may be removed from the kit of parts. The plate interface <NUM> may then be removed from its sterile packaging. The drape sleeve <NUM> may be already attached to the plate interface <NUM>. Alternatively, the drape sleeve <NUM> may be provided separately from the plate interface <NUM>. The actuation unit <NUM> is inserted into the drape sleeve <NUM>. The plate interface <NUM> is attached to the actuation unit <NUM>. Optionally, the actuation unit <NUM> comprises an insertion slot configured to securely receive the plate interface <NUM> in a fixed position. <FIG> shows the actuation system <NUM> after the plate interface <NUM> has been attached to the actuation unit <NUM>, with the drape sleeve <NUM> sandwiched therebetween.

The plate interface <NUM> may be locked into position on the actuation unit <NUM>. Optionally, the plate interface <NUM> is locked into position relative to the actuation unit <NUM> by locking means. Optionally the locking means comprises one or more mechanical clips. The clips may lock the plate interface <NUM> relative to the actuation unit <NUM> when pressure is applied pressing them together.

As shown in <FIG>, optionally the actuation unit <NUM> comprises an unlocking button <NUM>. The unlocking button <NUM> is configured to unlock the plate interface <NUM> from the actuation unit <NUM> when the unlocking button <NUM> is pressed. In an alternative embodiment, the unlocking button <NUM> is provided to the plate interface <NUM> (rather than to the actuation unit <NUM>). As a further alternative, an unlocking button <NUM> may be provided on each of the plate interface <NUM> and the actuation unit <NUM>. Other members such as a slider or a knob may be used as alternatives to a button for unlocking the plate interface <NUM> from the actuation unit <NUM>. Optionally, an electric switch such as an electromagnet may be provided for controlling attachment between the plate interface <NUM> and the actuation unit <NUM>.

When the plate interface <NUM> is properly attached to the actuation unit <NUM>, rotational and translational movement can be applied to any tool <NUM> that may be mounted onto the plate interface <NUM> and the actuation mechanisms <NUM>, <NUM> of the actuation unit <NUM>. This will be described in further detail below, with reference to <FIG>, for example.

<FIG> show different stages of a tool <NUM> being mounted onto the actuation system <NUM>. As shown in <FIG>, optionally the actuation system <NUM> comprises a tool cover <NUM>. For example, the tool cover <NUM> may be part of the plate interface <NUM>. Alternatively, the tool cover <NUM> may be a separate component from the plate interface <NUM>. Optionally, the tool cover <NUM> is configured to press the concentric tubes <NUM> into engagement with couplings <NUM> that impart motion to the tubes <NUM>. Of course, the tool cover <NUM> only presses the concentric tubes <NUM> when the concentric tubes <NUM> are supported by the plate interface <NUM>.

As shown in <FIG>, optionally the tool cover <NUM> can be opened and closed. <FIG> shows the tool cover <NUM> in an open configuration. The curved arrow in the top right corner of <FIG> represents the movement of the tool cover <NUM> when it opens. This allows access for the tool <NUM> to be loaded. As shown in <FIG>, the tool <NUM>, which may be a sterile surgical instrument, is inserted onto the plate interface <NUM>. The downwards arrow at the top of <FIG> shows the movement of the tool <NUM> on to the actuation system <NUM>. Alternatively, the tool cover <NUM> may be fixed in the closed position. The tool <NUM> may be slid in via the back of the plate interface <NUM> (by moving the tool <NUM> axially forwards).

As shown in <FIG>, the tool cover <NUM> may then be closed. The curved arrow at the top of <FIG> shows the movement of the tool cover <NUM> as it is closed. Optionally the tool cover <NUM> is locked into position. This can be done by, for example, a magnetic coupling and/or by mechanical locks. The tool cover <NUM> keeps the concentric tubes <NUM> of the tool <NUM> in engagement with the actuation means.

The tool <NUM> can be removed by unlocking and opening the tool cover <NUM> and removing the tool <NUM>. The tool <NUM> can be exchanged with another tool that corresponds to a different instrument. Alternatively, the tool <NUM> can be kept in position and only the tip <NUM> and/or end effector <NUM> of the tool <NUM> may be replaced.

At the end of the surgical operation, the tool <NUM> is removed from the actuation system <NUM>. The plate interface <NUM> may then be detached from the actuation unit <NUM>. The drape sleeve <NUM> is then removed from the actuation unit <NUM>. In preparation for a subsequent surgical operation, the actuation unit <NUM> may be wiped clean and left to dry. Typically, the actuation unit <NUM> is not sterilised. In contrast, the plate interface <NUM> is sterilised before the next surgical operation. The actuation unit <NUM> can then be again covered by the dust cover.

<FIG> schematically shows an alternative embodiment of a tool cover <NUM>. In the embodiment shown in <FIG>, the tool cover <NUM> is a separate component from the plate interface <NUM> and is configured to attach the plate interface <NUM>. Optionally, the tool cover <NUM> is fixed and does not open. The tool cover <NUM> forms a casing for containing parts of the tool <NUM>. The tool cover <NUM> may be configured to guide the couplings <NUM>, rather than press down the tool <NUM> onto the couplings <NUM>. Optionally, the tool cover <NUM> comprises a hole <NUM> in fluid communication with the interior <NUM> of the tubes <NUM> of the tool <NUM>. The hole <NUM> may be configured for connecting to a surgical tube <NUM> for suction and/or irrigation.

<FIG> is a schematic view of a tip <NUM> of the tool <NUM>. As shown in <FIG>, the tip <NUM> comprises an end effector <NUM>. The end effector <NUM> may come in different shapes and functions. For example, as shown in <FIG>, optionally the end of effector <NUM> is a grasper. Alternative end effectors include scissors, a needle and a suction tube.

As shown in close-up in <FIG>, optionally the actuation system <NUM> comprises a plurality of couplings <NUM>. The couplings <NUM> are for imparting motion to corresponding tubes <NUM> of the concentric tubes. Each coupling <NUM> is configured to move translationally along a first axis and to provide rotation about a second axis different from the first axis. <FIG> is a close-up view of one such coupling <NUM>. <FIG> show three couplings <NUM>, one for each tube <NUM>. In the example shown in <FIG>, the second axis (i.e. the axis of rotation) is orthogonal to the first axis (i.e. the axis of translational movement).

By providing that the axes for rotation and translational movement are different from each other, the rotational movement can be actuated from a position radially beside the concentric tubes <NUM>. This allows greater access to the tool <NUM> within the sterile environment. Additionally, by providing that the two axes are different from each other, different types of tool <NUM> can be actuated using the same actuation system <NUM>. This is explained in further detail below.

As mentioned above, different types of end effector <NUM> can be employed. Some end effectors have moving elements. The moving elements can be actuated through the means of the concentric tubes <NUM> and/or tendons <NUM>. <FIG> schematically shows a tool comprising a tip <NUM> attached to the actuation unit <NUM>. The tip <NUM> is controlled by the rotation and translational movement of the concentric tubes <NUM>. <FIG> shows an alternative tool attached to the actuation unit <NUM>. The tool shown in <FIG> comprises tubes <NUM> of a hybrid of a CTR and a tendon-driven robot in which the tip <NUM> is controlled by rotation and translation movement of the concentric tubes <NUM> and also by tendons <NUM>. The tendons <NUM> can be seen more clearly in the close-up view of the hybrid tool shown in <FIG>. As a further alternative not shown in the Figures, the tool may comprise tubes <NUM> of a tendon-driven robot (rather than a CTR or a hybrid robot).

As shown in <FIG>, optionally each coupling <NUM> comprises an actuation side coupling part <NUM>. The actuation side coupling part <NUM> is part of the actuation unit <NUM>. The coupling <NUM> further comprises a tool side coupling part <NUM>. The tool side coupling part <NUM> is part of the plate interface <NUM>. As shown in <FIG>, the actuation side coupling part <NUM> and the tool side coupling part <NUM> are configured to engage with each other when the plate interface <NUM> is attached to the actuation unit <NUM>. This allows the translational and rotational movements of the coupling to be imparted to the tool side coupling part <NUM> by the actuation side coupling part <NUM>.

The coupling <NUM> is configured such that the plate interface <NUM> can be detachably attached to the actuation unit <NUM>. When the plate interface <NUM> is attached to the actuation unit <NUM>, drive from the actuation unit <NUM> is transmitted to the tool <NUM> mounted on the plate interface <NUM>. As shown in <FIG>, optionally the actuation side coupling part <NUM> and the tool side coupling part <NUM> are configured to engage with each other by magnetic attraction and/or by mechanical means. The actuation side coupling part <NUM> may comprise a plurality of magnets <NUM>. The tool side coupling part <NUM> may comprise a corresponding plurality of magnets <NUM>. The magnets <NUM>, <NUM> are configured to engage with each other in pairs so as to transmit the drive. As shown in <FIG>, optionally the coupling <NUM> comprises a shaft <NUM> configured to transmit the rotational motion to the tool <NUM>. The shaft <NUM> is attached to a rotation motor of the rotation mechanism <NUM> of the actuation unit <NUM> (shown in <FIG>).

As shown in <FIG>, the tool side coupling parts <NUM> match the actuation side coupling parts <NUM>. The couplings <NUM> are configured to transmit a rotational motion and a translational movement that lie on different axes. Although magnets are shown in <FIG>, different means may be used. For example, one or more mechanical members may be used to engage the actuation side coupling part <NUM> with the tool side coupling part <NUM>. Optionally, the coupling <NUM> comprises means for self-aligning tool side coupling parts <NUM> of the plate interface <NUM> onto the actuation side coupling parts <NUM>.

As shown in <FIG>, optionally the translational movement is generated with a linear actuator. For example, as shown in <FIG> the actuation unit <NUM> optionally comprises a translation mechanism <NUM> comprising a motor connected to a ball screw <NUM>. However, other types of actuation may be used to generate the translational movement. For example, a hydraulic actuator could be used. Hydraulic actuators may be particularly desirable if the actuation system <NUM> is required to be compatible with MRI.

As shown in <FIG>, optionally a translation mechanism <NUM> comprising a motor and ball screw <NUM> is provided for each of the concentric tubes <NUM> of the tool <NUM>. As shown in <FIG>, optionally the actuation system <NUM> comprises a plurality of translation carts <NUM>. The translation carts <NUM> are configured to move translationally along the first axis. The translation carts <NUM> are configured to impart the translational movement to a corresponding coupling <NUM> and in turn to a corresponding tube <NUM>.

As shown in <FIG>, optionally each translation cart <NUM> comprises a rotation motor of the rotation mechanism <NUM>. The rotation motor may be embedded in the translation cart <NUM>. The rotation mechanism <NUM> comprising the rotation motor is configured to generate the rotation about the second axis which is imparted to the corresponding coupling <NUM>. As shown in <FIG>, the actuation side coupling part <NUM> is attached to the translation cart <NUM> in a way that allows the actuation side coupling part <NUM> to rotate relative to the translation cart <NUM>.

As shown in <FIG>, optionally each ball screw <NUM> is fixedly connected to a corresponding translation cart <NUM> via a ball screw nut <NUM>. The ball screws <NUM> otherwise pass through or around the other translation carts <NUM> without affecting them. As shown in <FIG>, optionally the actuation unit <NUM> comprises one or more rails <NUM>. The rails <NUM> are configured to allow for stable translational movement of the translation carts <NUM> along the first axis. In the example shown in <FIG>, the first axis is horizontal and the second axis is vertical.

As shown in <FIG>, each coupling <NUM> comprises a bevel gear <NUM>. The bevel gear <NUM> is configured to engage with a corresponding bevel gear <NUM> (e.g. see <FIG>) of the corresponding tube <NUM> so as to impart rotational motion to the tube <NUM>. The bevel gear <NUM> allows the axis of rotation to be changed when transferring the rotational movement from the rotation motor of the rotation mechanism <NUM> to the concentric tubes <NUM>. In the arrangement shown in <FIG>, the bevel gears <NUM>, <NUM> are arranged such that the axis of rotation changes by <NUM>°. However, alternative bevel gears may be used to provide different angles between the two rotational axes. It is not essential for the gear <NUM> to be a bevel gear, particularly when the gear <NUM> is configured to control tendons <NUM> (described below).

The curved arrow in the right-hand side of <FIG> shows the rotation of the bevel gear <NUM> around the rotational axis of the corresponding rotation motor (of the rotation mechanism <NUM>) embedded in the translation cart <NUM>. The horizontal arrow at the bottom of <FIG> indicates the movement of the translation carts <NUM> along the rails <NUM>.

As can be seen most clearly in <FIG>, optionally the tool comprises tubes <NUM> of a hybrid tool. As shown in <FIG>, optionally at least one of the tubes <NUM> comprises a bevel gear <NUM> around its circumference. For example, in the arrangement shown in <FIG>, each of the tubes 21a, 21b has a bevel gear <NUM> around its circumference.

As explained above, the bevel gear <NUM> allows the corresponding tube <NUM> to receive a rotational movement from a corresponding rotation motor that has a different axis of rotation. As can be seen from <FIG>, optionally the bevel gear <NUM> of the concentric tube <NUM> is configured to receive a translational force to cause translation movement of the corresponding tube <NUM> in one direction. For example, in the arrangement shown in <FIG>, each bevel gear <NUM> receives a force to cause the corresponding tube <NUM> to move translationally towards the left (in the orientation shown in <FIG>). This is because the bevel gear <NUM> of the tube <NUM> and the bevel gear <NUM> of the coupling <NUM> overlap each other when viewed along the axis of the tube <NUM>. When the coupling <NUM> is caused to move translationally by the translation mechanism <NUM> of the actuation unit <NUM>, the bevel gear <NUM> of the coupling <NUM> abuts and pushes the bevel gear <NUM> of the corresponding tube <NUM>. This causes the tube <NUM> to move proximally (i.e. in the direction away from the end effector <NUM> of the tip <NUM>). Optionally, the bevel gear <NUM> of the tube <NUM> has a dual purpose of receiving translational movement and rotational movement for the corresponding tube <NUM>.

As shown in <FIG>, optionally the tube <NUM> of the tool <NUM> comprises a flange <NUM> around its circumference. The flange <NUM> is spaced axially from the bevel gear <NUM>. The flange <NUM> is configured to receive a force that results in translational movement of the tube <NUM>. For example, in the arrangement shown in <FIG>, when the coupling <NUM> moves towards the right, the coupling <NUM> abuts against the flange <NUM>. This causes the corresponding tube <NUM> to move translationally towards the right (in the orientation shown in <FIG>).

As shown in <FIG>, optionally the coupling <NUM> comprises a flange <NUM>. The flange <NUM> of the coupling <NUM> is configured to engage with the corresponding flange <NUM> of the corresponding tube <NUM> so as to impart translational motion to the tube <NUM> in at least one direction. The engagement between the bevel gears <NUM>, <NUM> imparts translational movement to the tube <NUM> in the opposite direction.

<FIG> schematically shows an alternative arrangement that functions similarly to the arrangement shown in <FIG>. Differences are described below. As shown in <FIG>, the tool comprises a carriage <NUM> corresponding to each tube <NUM>. The carriages <NUM> carry respective tubes <NUM>. Each carriage <NUM> comprises a flange <NUM> configured to engage with the bevel gear <NUM> or flange <NUM> of the coupling <NUM>. Optionally, the couplings <NUM> do not have flanges <NUM> and the flange <NUM> of the carriage <NUM> contacts the bevel gear <NUM> of the coupling <NUM> directly. Optionally, the tubes <NUM> comprise a flange <NUM> or a change in diameter (e.g. see the outer tube 21a) configured to prevent linear motion of the tube <NUM> with respect to the carriage <NUM>.

In an alternative arrangement, the flange <NUM> of the tube <NUM> may fit within a groove of the coupling <NUM>. When the coupling <NUM> moves in either direction translationally, the inner surfaces of the groove of the coupling push the flange <NUM> of the tube <NUM>. This causes translational movement of the corresponding tube <NUM>. The flange <NUM> may cause translational movement of the tube <NUM> in both directions translationally.

As shown in <FIG>, optionally the actuation unit <NUM> comprises a plurality of translation carts <NUM>. The translation carts <NUM> are configured to move translationally along the first axis and impart the translational movement to a corresponding coupling <NUM>. Each translation cart <NUM> comprises a rotation motor of a rotation mechanism <NUM>. The rotation motor is configured to generate the rotation about the second axis which is imparted to the corresponding coupling <NUM>. Optionally, one translation cart <NUM> is provided for each tube <NUM> of the tool <NUM>. The number of tubes <NUM> is not particularly limited. The number of tubes <NUM> may be selected depending on the number of degrees of freedom required for the end effector <NUM> of the tool <NUM>. In the arrangement shown in the Figures, a first translation cart 18a is configured to impart translational and rotational movement to the outer tube 21a, a second translation cart 18b is configured to impart translational and rotational movement to the intermediate tube 21b, and a third translation cart 18c is configured to impart translational and rotational movement to the inner tube 21c.

As seen most clearly in <FIG>, optionally the tool <NUM> comprises a capstan <NUM> and at least one tendon <NUM> configured to be wound around the capstan <NUM> so as to actuate an end effector <NUM> of the tool <NUM>. Rotation of the capstan <NUM> causes a tendon <NUM> to be in tension, thereby actuating the end effector <NUM>. Optionally, a plurality of tendons <NUM> are provided. The tendons <NUM> may be attached to each other around the back of the capstan <NUM>. Optionally, the capstan <NUM> is configured to be controllably rotated in either direction around the same axis so as to apply a tension to a selected one of two tendons <NUM>. The tendons <NUM> allow a wider variety of end effectors <NUM> requiring independent actuation to be applied to the tool <NUM>. Optionally, the tool <NUM> comprises at least one segment controlled by tendons <NUM>. For example, tendons <NUM> can control bending of the tool <NUM> (e.g. left-right, or alternatively up-down) as well as the translation movement controlling advancement of the tip <NUM> forwards-backwards. Optionally, a capstan is not required. For example, optionally, the tendons <NUM> control movement of a component such as a rigid rod configured to straighten a flexible outer tube, thereby controlling movement of the tip <NUM>. As another example, the tip <NUM> may be driven using a rigid link (or a rigid tendon <NUM>).

As shown in <FIG>, optionally the capstan <NUM> is fixedly attached to a bevel gear <NUM> configured to rotate about the same axis as the capstan <NUM>. As shown in <FIG>, optionally the rotational movement is transferred from the bevel gear <NUM> of the coupling <NUM> via two bevel gears <NUM>. The two bevel gears <NUM> form part of the tool <NUM>. The bevel gears <NUM> effectively reverse the direction of rotation from the rotation motor of the rotation mechanism <NUM> of the actuation unit <NUM> to the capstan <NUM>. In an alternative embodiment, the capstan <NUM> may be fixedly attached to a gear that is complimentary to the bevel gear <NUM> of the coupling <NUM>. This allows the rotation from the rotation motor to be transferred to the capstan <NUM> without changing the direction of rotation. This reduces the number of gears in the system by one.

As shown in <FIG>, optionally the plate interface <NUM> comprises at least one rail <NUM>. For example, two rails <NUM> may be provided. The rails <NUM> are for allowing stable translational movement of the couplings <NUM>. As shown in <FIG> and <FIG>, for example, optionally the plate interface <NUM> comprises a plate section <NUM>. The plate section <NUM> is substantially flat and provides a boundary between a non-sterile environment and a sterile environment.

As shown in <FIG>, optionally a surgical tube <NUM> extends through the tubes <NUM> of the tool <NUM>. The surgical tube <NUM> may be for applying suction to the interior <NUM> of the tubes <NUM>. Alternatively, the surgical tube <NUM> may be for injecting one or more substances to the interior <NUM> of the tubes <NUM>. Optionally, the surgical tube <NUM> is for irrigating the interior <NUM> of the tubes <NUM>. The surgical tube <NUM> has sterile access to the interior <NUM> of the tubes <NUM>. This is because the region directly behind the tubes <NUM> is kept away from the actuation unit <NUM>.

As shown in <FIG>, optionally the actuation unit <NUM> comprises a fan <NUM>. The fan <NUM> is configured to cause gas <NUM> to flow through the plate interface <NUM> into the actuation unit <NUM>. In <FIG> the arrows inside the actuation unit <NUM> represent the flow of the gas through the actuation unit <NUM>. The flow of the gas is promoted by the fan <NUM>. The fan <NUM> produces the gas pressure below the plate interface <NUM> to be lower than the gas pressure above the plate interface <NUM>. The fan <NUM> produces negative air pressure below the plate interface <NUM> relative to the ambient pressure. Alternatively, flow may be driven by higher pressure being generated locally above the tool <NUM>. The arrow on the right-hand side of <FIG> represents the flow of the gas out through the actuation unit <NUM>. Optionally, the actuation unit <NUM> has a constant suction airflow. The airflow can cool down the motors of the actuation mechanisms <NUM>, <NUM> of the actuation unit <NUM>. The airflow can cool down the electronics of the actuation unit <NUM>. The flow of gas <NUM> is directed from the instrument area towards the actuation unit <NUM> so that no dirty air is pushed from the inside of the actuation unit <NUM> to the sterile environment. This helps to maintain the sterile environment.

As mentioned above, optionally the actuation system <NUM> is used to control the end effector <NUM> of a tool <NUM>. Alternatively, the actuation system <NUM> may be used for controlling a catheter. The actuation system <NUM> may be used for fine motor control. A different system may be used for initially performing coarse movements of the tool <NUM> or catheter.

The range of movement of each tube <NUM> may be limited by the size of the hole (and length of the rails <NUM>) in the plate section <NUM> of the plate interface <NUM>. The plate interface <NUM> can be designed to provide the required range of movement. Merely as an example, the range of movement of each tube <NUM> may be in the range of from about <NUM> to about <NUM>, for example about <NUM>.

The underside of the plate section <NUM> may be no longer sterile when the plate interface <NUM> is attached to the actuation unit <NUM>. The topside of the plate section <NUM> may remain sufficiently sterile to maintain the sterility of the surgical environment.

When the plate interface <NUM> is attached to the actuation unit <NUM>, the two halves of the couplings <NUM> are aligned to each other so as to form the couplings <NUM>. Optionally, the actuation unit <NUM> is provided such that each translation cart <NUM> has a corresponding home position. This makes it easier to align the two halves of the couplings <NUM> when the plate interface <NUM> is attached to the actuation unit <NUM>. Optionally, each tool side coupling part <NUM> of the coupling <NUM> has a corresponding home position in the plate interface <NUM> before the plate interface <NUM> is attached to the actuation unit <NUM>. For example, weak magnets may be applied to the underside of the cover <NUM> and to the top of the block that holds the bevel gear <NUM> so as to define the home positions.

Claim 1:
A robot that is a concentric-tube robot, a tendon-driven robot or a hybrid of a concentric-tube robot and a tendon-driven robot comprising:
an actuation system (<NUM>) for actuating at least one tube (<NUM>) of the robot; and
a tool (<NUM>) comprising the at least one tube, wherein the tool is removable from the actuation system, and
wherein the actuation system is configured to actuate the at least one tube from radially to one side of the at least one tube,
wherein the actuation system comprises at least one coupling (<NUM>) for imparting motion to a corresponding tube of the at least one tube, each coupling configured to move translationally along a first axis and to rotate about a second axis different from the first axis,
wherein each coupling comprises a bevel gear (<NUM>) configured to engage with a corresponding gear (<NUM>) of the corresponding tube so as to impart rotational motion to the tube,
characterised in that each tube is carried by a respective carriage (<NUM>) that comprises a flange (<NUM>) configured to engage with the corresponding coupling such that translational motion is imparted to the tube in one direction, the engagement between the gears imparting translational motion to the tube in the opposite direction.