Apparatus

Abstract

An aspect of the disclosure provides a surgical robot (10) for deployment in an internal body lumen of a human or animal subject, the robot comprising: an inflatable scaffold (12) having a collapsed state for delivery to a target site in the lumen and an inflated state in which the scaffold defines an open cavity (18), a manipulator (14) movable in the cavity for manipulating a medical device; and a soft actuator (16) operable by fluid pressure to move the manipulator (14) by applying force between the scaffold (12) and the manipulator, wherein the scaffold (12) is arranged around the soft actuator (16) to provide protection between the soft actuator and the body lumen.

Description

[0001] APPARATUS

[0002] Field of Invention

[0003] The present invention relates to apparatus and methods, and more particularly to robots for conducting medical procedures, such as procedures involving deployment in an internal body lumen of a human or animal subject, more particularly such robots may be used in minimally-invasive procedures such as those conducted using endoscopes .

[0004] Background

[0005] Colorectal cancer was estimated to have caused the second highest number of cancer-related deaths globally in 2020, and the third highest number of incidences. As a result, there is an intense research focus on developing improved screening and treatment options .

[0006] Among recently developed surgical techniques for early colorectal cancers is Endoscopic Submucosal Dissection (ESD) , which offers patient benefits such as reduced recurrence rate, the possibility of removing large early cancers en bloc, and increased resection rate, in comparison to the more common procedure Endoscopic Mucosal Resection (EMR) .

[0007] However, procedure times and perforation rates are higher for ESD as a result of the high technical difficulty. Robotic devices may simplify difficult ESD procedures, lessening the learning curve and / or reducing the staff required; however, there is no standard flexible robotic endoscope in spite of recent advances. Challenges facing designers of robotic devices include reducing patient discomfort and achieving cecal intubation rates comparable to standard endoscopy. Cecal intubation is achieved when the endoscopist successfully reaches the cecum with the endoscope, and bulky robotic mechanisms can make navigation and insertion harder and cause increased patient discomfort, resulting in the need for sedation or longer procedure times.

[0008] In a conference proceedings article entitled "Pop-Up Soft Robot for Minimally Invasive Surgery" (Mark Runciman, James Avery, George Mylonas; Hamlyn Centre, Imperial College London, London, UK; Hamlyn Symposium on Medical Robotics 2022) one possible solution to this problem is proposed.

[0009] Summary

[0010] The present disclosure aims to provide a soft robot which can be operated by pneumatic or hydraulic actuators and in which improved control of an end effector can be provided.

[0011] Aspects and examples of the invention are set out in the claims and aim to address this technical problem and other technical problems .

[0012] The present disclosure provides a collapsible, soft robot structure and actuators for the control of a medical device, such as a surgical implement during ESD. This robot may be used with a flexible endoscope.

[0013] In an embodiment the robot of the present disclosure is capable of high accuracy and repeatability, and force exertion and optionally also sensing.

[0014] The robot structure may comprise a scaffold. The scaffold and actuators may be composed of low-profile polymer sheets with sealed inflatable chambers disposed between the sheets. Such actuators may be referred to as "pouch actuators". This usually is in reference to pneumatic actuators but the present disclosure envisages hydraulic actuation for improved control. In an aspect there is provided a surgical robot for deployment in an internal body lumen of a human or animal subject, the robot comprising: an inflatable scaffold having a collapsed state for delivery to a target site in the lumen and an inflated state in which the scaffold defines an open cavity, a manipulator movable in the cavity for manipulating a medical device; and a soft actuator operable by fluid pressure to move the manipulator by applying force between the scaffold and the manipulator, wherein the scaffold is arranged around the soft actuator, to be disposed between the soft actuator and the body lumen when the scaffold is inflated in the body lumen.

[0015] The soft actuator may be supported by the scaffold. For example, the soft actuator may be carried by a wall of the open cavity. The soft actuator may be carried on an inward facing surface of said wall .

[0016] The scaffold may be configured to constrain a radial extent of the robot .

[0017] Application of fluid pressure to operate the actuator may cause a longitudinal expansion or contraction of the actuator to move the manipulator. The actuator may be configured so that transverse expansion or contraction of the actuator (e.g. bulging of the pouch actuator) during said operation is directed in a radially inward direction away from a wall of the body lumen. This may assist in reducing likelihood of perforation of the lumen.

[0018] The scaffold may also be arranged to protect the soft actuator from force exerted by the body lumen, such as gut peristalsis.

[0019] The soft actuator may also be positioned relative to the scaffold to inhibit transverse deflection of the scaffold by the transverse force applied by the actuator to the manipulator. The di sclosure al so provides a surgical robot for deployment in an internal body lumen of a human or animal subj ect , the robot comprising : an inflatable scaf fold having a collapsed state for delivery to a target site in the lumen and an inflated state in which the scaffold defines an open cavity, a manipulator movable in the cavity for manipulating a medical device ; and a soft actuator anchored to the scaf fold for applying transverse force by applying force between the scaf fold and the manipulator to move the manipulator in a transverse direction, radially outwards within the cavity towards the scaf fold, wherein the soft actuator i s positioned relative to the scaf fold to inhibit transverse deflection of the scaffold by the transverse force .

[0020] The soft actuator may be anchored to the scaf fold and aligned with a wall of the scaffold thereby to inhibit transverse deflection of the scaf fold . For example the soft actuator may be carried on a surface of the wall so that a line of action of force generated by the actuator i s aligned with the wall . The actuator may al so be arranged so that the force generated by the actuator i s perpendicular to the apex ridges ( corners ) of the scaf fold structure . In thi s configuration, tension due to the actuators tends only to radially compres s the scaf fold at the location of the actuator rather than causing a longitudinal buckling of the scaf fold .

[0021] The soft actuator may be di sposed in the open cavity of the scaf fold proximal of the manipulator .

[0022] The soft actuator may be operable to lengthen and to contract in a direction along the surface of the wall for applying force to move the manipulator . For example the wall may be straight .

[0023] An actuator linkage may be connected between the manipulator and the soft actuator and routed via a line guide element anchored to the scaf fold and configured to guide a control line of the linkage movably around a bend .

[0024] The linkage may be anchored to the scaf fold by the actuator . The actuator may be flexibly anchored by a tether . The tether may be connected to an apex of the scaf fold .

[0025] The linkage may be configured to provide a block and tackle arrangement . For example it may comprise a movable member and at least line guide element di sposed on the movable member . Thi s line guide element may be configured to guide a control line of the linkage movably around a bend .

[0026] A control line of the linkage is connected to the manipulator for moving the manipulator and routed via at least one line guide element disposed on the movable member .

[0027] The control line connected to the manipulator may be anchored to the scaf fold, for example at an apex of the scaf fold .

[0028] The scaffold compri ses a plurality of elongate inflatable pillars mutually aligned between adj acent apices of the scaf fold . The pillars may be straight . In some embodiments curved pillars may be used .

[0029] The scaf fold may be of a unitary construction integrally formed from two laminated sheets of a flexible material , for example wherein the laminated sheets are configured to be folded, such that the folds provide apices of the scaffold . Apertures may be provided along the apices of the scaf fold and line guide elements , comprising channels for guiding the control line , may be held to these apertures by clips . The channel s of these line guide elements may be lined with a lubricious material to reduce friction as the control line runs through the line guide elements. The line guide elements may thus provide the function of a pulley or capstan.

[0030] The sheets comprise rows of apertures configured to be disposed along the apices of the scaffold between adjacent pillars. At least one of the apertures may serve to anchor the soft actuator to an apex. A clip may extend through one or more of the apertures to anchor the soft actuator.

[0031] The sheets which make up the scaffold may be held together by linear bond regions 40, such as welds. The linear bond regions 40 extend between the apertures 42 and may bound unbonded regions of the sheets so that, when fluid pressure is applied between the sheets, the unbonded regions inflate to form the pillars with apertures between them at the apices of the scaffold.

[0032] The scaffold may comprise a first fluid port 44, arranged for supplying inflation fluid to the scaffold and may also carry a second fluid port, which may be arranged to carry inflation fluid inside the scaffold to the soft actuator.

[0033] The manipulator may comprise a shaft pivotably mounted in the cavity. The shaft may be arranged so that an elongate medical device can be disposed through a lumen of the shaft. Examples of medical devices include a surgical tool having an end effector disposed at a distal end of an elongate flexible body.

[0034] The manipulator shaft carries an extension portion, which is extensible to advance in an axial direction from the cavity and to retract. The shaft and the extension portion together accordingly provide an extensible rigid member.

[0035] The scaffold carries a bendable coupling, in the scaffold proximal of the shaft, arranged to flexibly support a part of the elongate medical device so that a portion of the medical device held in the shaft can pivot .

[0036] The bendable coupling may be configured to allow the elongate medical device to be advanced and retracted .

[0037] The shaft may carry an instrument coupling configured to detachably retain the elongate medical device in a selected axial position relative to the shaft .

[0038] The instrument coupling may couple the elongate medical device to the shaft such that advancement of the elongate medical device causes extension of an extension portion of the shaft .

[0039] The soft actuator and the scaffold together may both be arranged as a laminar structure configured to be collapsed, e . g . , wrapped or rolled into a collapsed configuration for delivery to a target site . It may also be arranged to unfurl from the collapsed state in response to inflation .

[0040] It can therefore be seen that a robotic arm for controlling an end effector of the surgical implement i s provided by a manipulator of the robot . This manipulator i s moved by controlling control lines , such as wires or cables , attached to actuators which are carried by the scaf fold .

[0041] The scaf fold, when inflated, may serve to stabili se the manipulator in the body lumen into which it i s deployed . It may al so carry line guide elements ( e . g . pulleys and capstans etc . ) which guide the control lines between the actuators and the manipulator . The control lines may provide mechanical actuation force to move a medical instrument held in the manipulator relative to the scaf fold . The manipulator and the control lines may both be provided inside an open cavity of the scaffold and the actuators may be provided inside that same cavity. Typically the actuators are proximal of the manipulator. The manipulator may comprise a rigid shaft arranged to pivot with respect to a bendable or pivotable coupling disposed proximal of the manipulator in the scaffold. The bendable or pivotable coupling may be configured to enable a part of the medical device to be pivotably connected to the scaffold, proximal of the manipulator. This can enable movement of the manipulator by the control lines to provide well defined displacements with a known mechanical advantage.

[0042] The actuators are typically provided inside this scaffold, for example scaffold may surround and protect the actuators inside a cavity of the scaffold. The actuators may be controlled by control of the pressure of the fluid (gas or liquid) that fills the actuators. The pressure of this fluid (e.g. the pressure inside the actuators can be used to estimate the forces exerted on the end effector) . This feedback enables accurate motion control of the manipulator. In prior art devices this may not be possible because motion of the body lumen (such as peristalsis of the gut) may deform the actuators and provide unwanted and unpredictable pressure changes.

[0043] The actuators could be thought of as 'muscles' . Similarly, the supportive structure of the device, referred to herein as a scaffold, is also pressurised with a fluid and acts as the 'skeleton' that allows the actuators to exert forces on the robot arm.

[0044] Embodiments of the disclosure provide local cable actuated movement driven by distal pressurised fluid tubes. These may not face the same issues as traditional Bowden cables. Namely that the curvature of the colon can make end-effector movement difficult to predict with Bowden cables and devices which use Bowden cables are generally limited to the sigmoid / descending colon. By contrast embodiments of the present disclosure may be able to access the whole colon with the same degree of end-effector functionality.

[0045] Embodiments provide the incorporation of native / natural movement and haptics for surgeons in performing procedures. For example, in an embodiment haptic feedback is provided at a control interface of the device based on the pressure in the fluid in the actuators.

[0046] Embodiments of the disclosure are configured to allow control of any traditional surgical tool. For example, such a tool may be threaded through the manipulator shaft of the devices described herein so that the surgical tool can be manipulated.

[0047] Embodiments may be configured to accommodate any 'off-the-shelf' flexible endoscopic instrument and instruments can be exchanged while preserving the working channel (s) and functionalities of the endoscope .

[0048] The actuators and / or the scaffold may be made from sheets of flexible material such as a thin film polymer. This can permit a low profile, pop-up functionality (also allowing tissue retraction for stabilisation) , and MRI compatibility, as well as enabling it's use in small incision or natural orifice introduction.

[0049] Embodiments of the disclosure are primarily concerned with medical and surgical applications. However, the scaffold "skeleton" and actuator "muscles" could be used in other settings outside of gastrointestinal surgery, where precise and accurate movement is required in small, hard-to-reach places.

[0050] These and many advantages of the present disclosure will become apparent to the skilled addressee.

[0051] Brief Description of Drawings Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings, in which:

[0052] Figure 1 shows an isometric view of a surgical robot according to the present disclosure;

[0053] Figure 2 shows a schematic view of an actuator and an actuator linkage for use in a robot such as that shown in Figure 1;

[0054] Figure 3 shows a side view of a robot such as that shown in Figure 1;

[0055] Figure 4 shows a view of a partly disassembled robot such as that shown in Figure 1;

[0056] Figure 5 is a flow chart illustrating a method of operation of the device

[0057] In the drawings like reference numerals are used to indicate like elements .

[0058] Specific Description

[0059] Figure 1 shows a surgical robot 10 which comprises an inflatable scaffold 12, a manipulator 9, 11, 14, a soft actuator 16 (not visible in Figure 1) . The soft actuator is connected to the manipulator 14 by a linkage 20 (shown in Figure 2) comprising a control line 15.

[0060] The scaffold 12 surrounds at least a proximal portion of the manipulator 9, 11, 14, which is positioned to be able to protrude distally from an open distal end face of an open cavity 18 provided by the scaffold 12.

[0061] The manipulator may comprise a manipulator coupling 14 and a shaft 9, 11. The manipulator shaft typically comprises a pivotably mounted shaft portion 11, which may carry the manipulator coupling 14 and an extensible portion 9 (shown in Figure 3) . The manipulator coupling 14 is connected to a plurality of control lines 15 which suspend the manipulator coupling 14 near the open distal end face of the scaffold.

[0062] The scaffold 12 comprises a triangular structure, such as a triangular prism. This prism defines an internal open cavity 18 in that this cavity 18 is surrounded by the inflated walls of the scaffold 12. Each wall of the scaffold 12 comprises a plurality of inflatable sections which are joined together to form the wall. These sections are configured to be inflated so that the walls can become at least semi-rigid. The walls together enclose the sides of the cavity 18. The inflatable sections of the scaffold 12 are configured to be fluidly connected to a source of pressurised fluid for inflating the scaffold. When inflated these sections may form "pillars" of the scaffold which may be straight.

[0063] The inflation pressure of the scaffold may be selected so that the inflated walls of the scaffold are at least semi-rigid. For example, the pressure may be selected so that the inflated walls are rigid enough to provide protection of the cavity 18 against forces, such as peristalsis of the gut, associated with deployment in a body lumen of a human or animal subject.

[0064] The inflatable sections of the walls are also configured so that, when they are deflated the scaffold can be collapsed (e.g. , rolled up) . The collapsed configuration may be provide an arrangement suitable for allowing the robot to be carried on or in the shaft of a minimally-invasive medical device, such as an accessory for an endoscope.

[0065] This can enable the robot to be carried to the target site in a body lumen of a patient for performing a minimally invasive procedure . As noted above , scaf fold of the robot illustrated in Figure 1 is arranged so that the control lines 15 provide three transverse connections to the manipulator coupling 14 . The control lines 15 may be angularly separated around the manipulator so that the manipulator coupling 14 can be controlled to move in two dimensions ( e . g . up-down, left right ) by applying tension to the control lines . Accordingly, the manipulator coupling 14 i s connected to each of the three apices of the triangular scaf fold 12 by each of three separate control lines 15 , one line 15 to each apex . Each control line 15 i s connected at one end to the manipulator coupling 14 , and then i s routed via the corresponding apex of the scaf fold 12 to a respective corresponding actuator 16 .

[0066] The actuators 16 typically each comprise an inflatable structure which i s configured to contract longitudinally when it i s inflated . In other words , a structure in which transverse expansion causes longitudinal contraction and vice versa . One way to provide such a structure is illustrated in Figure 2 . As shown in Figure 2 the actuator 16 may compri se a series of flat hexagonal chambers formed between two flexible sheet-like elements , and j oined at their edges in a line to form a flat shape with a concertina appearance when viewed in plan . The flexible sheet like elements may be of a material which i s flexible but substantially non-extensible . As a result , upon inflation, transverse ( outward) bulging of the sheetlike elements causes longitudinal contraction of the actuator as a whole . Typically, such an actuator may contract by a fixed percentage of its total length .

[0067] The actuators 16 may be protected by the scaf fold, for example they may be di sposed in the open cavity 18 and may be positioned proximal of the manipulator coupling in that cavity . They may, for example , be carried by an internal surface of a wall of the scaf fold 12 . Thi s may provide both protection of and support to the actuator 16 . The actuator i s connected at one end by a tether 26 to an apex of the scaf fold 12 . The other end of the actuator 16 is connected by a control line 15 to the manipulator 14 . The control line i s routed via one or more line guide elements 22 , 24 to the manipulator 14 . The combination of these guide members and the control line 15 may provide an actuator linkage which enables the operation of the actuator to move the manipulator . It can thus be seen that each control line 15 can be independently controlled by its corresponding actuator 16 . The number of control lines 15 and the number of actuators 16 may vary according to the nature and extent of positional control of the manipulator which i s desired . In some embodiments at least one actuator and actuator linkage is provided on each wall of the scaf fold, the control wire 15 of each actuator linkage being routed to the manipulator coupling 14 via a guide element disposed on a di f ferent one of the apices of the scaf fold from the other control wires .

[0068] Generally, the actuator 16 i s aligned with a wall of the scaffold, for example it may lie flat against an internal surface of the wall of the scaf fold . The actuator 16 is tethered at one of the apices and a control line extends from the other end of the actuator to a guide element at the adj acent apex of the scaf fold . In thi s configuration contraction of the actuator may exert a force which i s aligned with the wall of the scaf fold . The tether and the control line may each be arranged so that the force i s substantially perpendicular to the apex of the scaf fold and in the plane of the wall . Thi s i s one way to ensure that operation of the actuator does not cause longitudinal buckling of the scaffold structure , or unwanted deflection of the manipulator .

[0069] The scaf fold 12 compri ses a first fluid port , arranged for supplying inflation fluid to the scaf fold . This may be couplable to a lumen of an elongate medical device such a catheter . The scaffold may also carry a second fluid port for supplying inflation fluid to the soft actuator. The second fluid port may be inside the scaffold 12.

[0070] It can be seen by inspection of Figure 1 that, with soft actuators such as those described above carried on inward facing surfaces of the walls of the scaffold. The actuators may be protected from a lumen in which the robot is deployed by the scaffold. Conversely, the walls of the lumen are themselves shielded from the actuators by the walls of the scaffold. It can therefore be seen that the scaffold, which serves to support the manipulator, also serves to support and protect the soft actuators.

[0071] It can also be seen that in the case of a triangular scaffold, such as the triangular prism illustrated in Figure 1, the manipulator 14 may be connected to three separate control lines 15 each of these three lines may be controlled by a separate corresponding one of a plurality of actuator linkages and actuators 16. Each such actuation arrangement being disposed on a different internal wall of the scaffold. One possible actuation arrangement will now be described with reference to Figure 2. In Figure 2 the scaffold 12 is not shown to assist clarity. However, the line guide elements 22, 24 are typically disposed on the apices of the scaffold, for example longitudinally spaced apart along the length of the scaffold.

[0072] The line guide elements may comprise channels for guiding a control line, and the control line may be routed through the channel. The channel may comprise a tube and may be lined with a lubricious material to facilitate sliding of the control line through the channel. The line guide elements may provide the function of a pulley or capstan, allowing the control line to slide or run around the line guide element to provide a bend in the control line. As illustrated, the actuation arrangement shown in Figure 2 comprises a tether 26 an actuator 16 a first control line 15' a second control line 15, a first line guide element 22, a second line guide element 24, a movable member 28, a third line guide element 30, a fourth line guide element 32, and a fifth line guide element 34. The tether 26 connects the rear side of the actuator 16 to an apex of the scaffold 12. The other end of the actuator 16 is connected to the first control line 15' . The first control line 15' is then routed to the first line guide element 22 which provides a 90-degree bend in the first control line 15' . The first control line 15' is then routed to the second line guide element 24 which is disposed on the same apex of the scaffold 12, longitudinally spaced apart from the first line guide element 22. The second line guide element 24 carries the first control line 15 prime through a further 90-degree bend where it terminates with a connection to the moveable member 28.

[0073] The moveable member 28 carries a third line guide element 30. The third line guide element 30 is configured to provide a 180-degree bend in a line. Disposed on the opposite adjacent apex of the scaffold is the fourth line guide element 32. The second control line 15 is anchored to the apex adjacent to the fourth line guide element 32 and then routed through the third line guide element 30 on the moveable member before passing around the fourth line guide element 32 and optionally back through the third line guide element 30 through a further 180-degree bend from where it returns to the fourth line guide element 32. The control line then follows a further 90-degree bend around the fourth line guide element 32 from where it is routed along the apex of the scaffold to the fifth line guide element 34. The fifth line guide element 34 provides a further bend in the second control line 15 to allow it to connect to the manipulator 14. Other than the part of the control line 15 which links the manipulator 14 to the fifth line guide element 34 the control lines 15, 15 prime may be predominantly positioned along the surface of, or along the apices of the walls of the scaffold 12. This is one way in which the embodiments of the present disclosure may be arranged to reduce buckling (e.g. longitudinal deflection) of the scaffold. It will also be appreciated that the actuator arrangement shown in Figure 2 provides a block-and-tackle arrangement of control lines. Other ways of providing mechanical advantage to the actuators 16 may be employed.

[0074] Referring now to Figure 4 there can be seen a side view of a soft robot such as that illustrated in Figure 1. In this drawing, the walls of the scaffold 12 are shown as being partially transparent to enable the position of the manipulator to be more clearly seen. As illustrated in Figure 4 the manipulator 14, 11, 9 comprises a manipulator coupling to which the control lines 15 can be connected. It also comprises a shaft 11 which may be provided by a substantially rigid elongate member having a lumen there through. A medical device 7 may be passed through this lumen so that it is supported by the shaft 11 and can be moveably controlled by the manipulator coupling 14.

[0075] An instrument guide 3 may also be provided, for example coupled to one of the apices of the scaffold toward the proximal end of the scaffold. This instrument guide 3 may enable a medical instrument 7 to be passed from the proximal end of the scaffold and routed towards the shaft 11. The instrument guide 3 may be substantially flexible and / pivotable to enable the instrument 7 to be easily advanced and retracted through the guide whilst also stabilising the instrument relative to the scaffold.

[0076] The manipulator shaft 11 may comprise an extension portion 9 which is operable to extend and retract from a distal end of the shaft 11. The extension portion and the shaft may be concentrically arranged so that the two can be extended telescopically, one from the other. It can thus be seen that the shaft and extension portion provide an extensible rigid member. A distal end of the extension portion may carry an instrument coupling configured to latch on to a part of a medical instrument disposed through it. Examples of such arrangements include magnets, detents, spring latches, interference fits, and other arrangements. This detachable coupling of the medical device 7 to the extensible portion 9 of the shaft 11 may enable advancement and retraction of the medical instrument 7 to cause a corresponding extension or retraction of the manipulator shaft 11, 9. It can thus be seen that an otherwise flexible medical device can be rigidly supported along an extensible length of its distal end. In combination with the transverse control offered by the control lines, this can provide 3D control of the medical device 7. This can enable an end effector of the device to be manipulated in three dimensions.

[0077] Operation of the robot described in reference to Figure 1, Figure

[0078] 2 and Figure 3 will now be described.

[0079] First, to prepare the device for deployment, an elongate medical device suitable for deployment in a minimally-invasive procedure is advanced through the instrument guide 3 and the shaft 7, 9 of the manipulator. The scaffold and actuators, in a deflated state, are then collapsed around the shaft of the medical device and the shaft of the manipulator. For example, they may be rolled into a low-profile configuration. With the robot in this collapsed configuration the minimally-invasive medical device is advanced to a target site in a human or animal patient. For example, it may be advanced to the target site in an accessory channel of an endoscope or by similar means. Once at the target site a pressurized fluid is supplied to the scaffold to cause the walls of the scaffold to inflate. The scaffold walls are inflated until they become at least semi rigid . The actuator linkages connected between the manipulator and the actuators which are carried by each of these wall s are arranged so that , when the scaf fold i s fully inflated, the manipulator i s held in a predetermined position ( such as in the centre of the open cavity formed by the inflated scaf fold) . Thi s may be done by appropriate selection of the length of the control lines . I f necessary, the medical device can be advanced or retracted slightly to cause the instrument coupling at the di stal end of the shaft 7 , 9 to engage with the medical device . Once thi s has been done advancement and / or retraction of the medical device causes a corresponding extension or contraction of the shaft 7 , 9 . To cause a transverse deflection of the medical instrument of the medical device a selected one of the actuators can be provided with a pres suri zed fluid to cause a transverse expansion of the actuator and a corresponding longitudinal contraction . Thi s longitudinal contraction causes the actuator 16 to pull on the first control line 15 prime . Accordingly, the tension in the first control line 15 prime causes the moveable member 28 to be pulled away from the fourth line guide element 32 . The length of the second control line 15 which i s looped around the third line guide element 30 ( on the moveable member ( 28 ) ) and the fourth line guide element 32 i s therefore extended . In the arrangement shown in Figure 2 thi s provides a four to one mechanical advantage , but other force scaling' s may be provided by other types of arrangement . Thi s causes a corresponding movement of the manipulator 14 due to the tension in the second control line 15 . In some embodiments the mechanical advantage provided by the actuator linkage is selected based on the extent of longitudinal contraction of the corresponding actuator so that a complete operation of the actuator 16 corresponds to a movement of the manipulator 14 across substantially all of the available range of movement . It can be seen that, because the shaft 7, 9 is pivotably coupled between the manipulator 14 and the instrument coupling 3 tension in the control wires provides a pivoting / leaver like movement of the shaft 7, 9.

[0080] Advantageously, because the actuators 16 are disposed inside the scaffold (protected by the scaffold) they are shielded from external forces which may be applied to them during medical procedures. It will be appreciated that such external forces may cause distortion of the actuators such as compression and this might give rise to unwanted movement or deflection of the manipulator. It can therefore be seen that one advantage of the present disclosure is to provide improved control of the manipulator. In addition, because the actuators are arranged to provide forces transvers (e.g. , perpendicular) to a longitudinal axis of the scaffold and / or the medical instrument 7 then operation of the actuators does not tend to cause a buckling or transverse stress on the shaft of the medical instrument 7. This may also provide improved control of the manipulator 14.

[0081] Turning now to Figure 5 there can be seen a view of the scaffold in a partially disassembled configuration. The scaffold may comprise two flat sheets of material such as a polymer. Typically, these sheets are flexible but not extensible (e.g. not ductile or elastic) . The two sheets may be held together in a layered structure, one on top of the other, with welds around their peripheral edges to provide an inflatable pouch between the two sheets. A series of further welds may also be provided to subdivide this pouch into a set of compartments. These welds may comprise short straight linear welds spaced apart across the width of the sheet and aligned with the length of the sheet. These straight linear welds may be broken into three sections, each section corresponding to one wall of the scaffold when inflated. Between these breaks in the welds apertures through the sheets may be provided and arranged so that , when the scaf fold is inflated these apertures are provided at the apices of the scaf fold . These apertures at the apices provide anchor points for the guide elements and / or the control lines which are used to tether the actuators .

[0082] One benefit of using fluid actuated soft actuators i s that measurements of the pres sure of the actuation fluid can be used to estimate any external forces present on the shaft of the robot . Thi s has advantages over cable-driven systems that suf fer from friction that i s hard to predict . For example , i f long, force transmitting cables were used to move the shaft of the current robot instead of the soft actuators , measuring the tensions of the cables at the proximal end would not allow enable force estimation because of friction ef fects along the cable lengths . Thi s i s especially true when the long cables pass through very curved paths , such as in the colon / gastrointestinal tract . However , thi s would be possible with fluid actuation because equilibrium of the pres sure in the supply tube will be reached after any movement , adj usting for changes in elevation of the ends of the tube .

[0083] Any feature of any one of the examples di sclosed herein may be combined with any selected features of any of the other examples described herein . For example , features of methods may be implemented in suitably configured hardware , and the configuration of the specific hardware described herein may be employed in methods implemented using other hardware .

[0084] It will be appreciated from the discussion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generali sed, removed or replaced as described herein and as set out in the claims . With reference to the drawings in general , it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein . It will be appreciated however that the functionality need not be divided in this way, and should not be taken to imply any particular structure of hardware other than that described and claimed below . The function of one or more of the elements shown in the drawings may be further subdivided, and / or di stributed throughout apparatus of the di sclosure . In some embodiments the function of one or more elements shown in the drawings may be integrated into a single functional unit . The above embodiments are to be understood as illustrative examples . Further embodiments are envisaged . It i s to be understood that any feature described in relation to any one embodiment may be used alone , or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments , or any combination of any other of the embodiments . Furthermore , equivalents and modi fications not described above may al so be employed without departing from the scope of the invention, which i s defined in the accompanying claims .

Claims

Claims1. A surgical robot (10) for deployment in an internal body lumen of a human or animal subject, the robot comprising: an inflatable scaffold (12) having a collapsed state for delivery to a target site in the lumen and an inflated state in which the scaffold defines an open cavity (18) , a manipulator (14) movable in the cavity for manipulating a medical device; and a soft actuator (16) operable by fluid pressure to move the manipulator (14) by applying force between the scaffold (12) and the manipulator, wherein the scaffold (12) is arranged around the soft actuator (16) to provide protection between the soft actuator and the body lumen .

2. The robot of claim 1 wherein the soft actuator (16) is supported by the scaffold.

3. The robot of claim 1 or 2 wherein the soft actuator (16) is carried by a wall of the open cavity (18) , for example wherein the soft actuator is carried on an inward facing surface of said wall.

4. The robot of any preceding claim in which the scaffold is configured to constrain a radial extent of the robot.

5. The robot of claim 4 wherein application of fluid pressure to operate the actuator causes a longitudinal expansion or contraction of the actuator to move the manipulator, and the actuator is configured so that transverse expansion or contraction of the actuator during said operation is directed in a radially inward direction away from a wall of the body lumen.

6. The robot of any preceding claim wherein the scaffold (12) is arranged to protect the soft actuator (16) from force exerted by the body lumen.

7. The surgical robot of any preceding claim wherein the soft actuator is positioned relative to the scaffold to inhibit transverse deflection of the scaffold by the transverse force .

8. A surgical robot for deployment in an internal body lumen of a human or animal subject, the robot comprising: an inflatable scaffold (12) having a collapsed state for delivery to a target site in the lumen and an inflated state in which the scaffold defines an open cavity, a manipulator (14) movable in the cavity for manipulating a medical device; and a soft actuator anchored to the scaffold for applying transverse force by applying force between the scaffold and the manipulator to move the manipulator in a transverse direction, radially outwards within the cavity towards the scaffold, wherein the soft actuator is positioned relative to the scaffold to inhibit transverse deflection of the scaffold by the transverse force.

9. The robot of any preceding claim wherein the soft actuator is anchored to the scaffold and aligned with a wall of the scaffold thereby to inhibit transverse deflection of the scaffold, for example wherein the soft actuator is carried on a surface of the wall, for example wherein the soft actuator is disposed in the cavity (18) proximal of the manipulator (14) .

10. The robot of claim 9 wherein the soft actuator (16) is operable to lengthen and to contract in a direction along thesurface of the wall for applying force to move the manipulator , for example wherein the wall is straight .

11. The robot of any preceding claim comprising a linkage (20) connected between the manipulator (14) and the soft actuator (16) and routed via a line guide element (22 , 24) anchored to the scaffold and configured to guide a control line (15) of the linkage movably around a bend.

12. The robot of claim 11 wherein the linkage is anchored to the scaffold (12) by the actuator (16) , for example wherein it is flexibly anchored by a tether (26) .

13. The robot of claim 8 or 9 wherein the linkage comprises a movable member (28) and at least line guide element (30) disposed on the movable member (28) and configured to guide a control line (15) of the linkage movably around a bend.

14. The robot of claim 13 wherein a control line (15) of the linkage is connected to the manipulator (14) for moving the manipulator and routed via at least one pulley (30) disposed on the movable member.

15. The robot of claim 14 wherein the control line (15) connected to the manipulator is anchored to the scaffold, for example at an apex of the scaffold (12) .

16. The robot of any preceding claim wherein the scaffold comprises a plurality of elongate inflatable pillars (13) mutually aligned between adjacent apices of the scaffold, for example wherein the pillars (13) are straight.

17. The robot of any preceding claim wherein the scaffold is of a unitary construction integrally formed from two laminated sheetsof a flexible material, for example wherein the laminated sheets are configured to be folded to provide apices of the scaffold.

18. The robot of claim 17 as dependent upon claim 10 wherein the sheets comprise rows of apertures configured to be disposed along the apices of the scaffold between adjacent pillars.

19. The robot of claim 18 wherein at least one of the apertures serves to anchor the soft actuator to an apex, for example wherein a clip extends through two of the apertures to anchor the soft actuator .

20. The robot of claim 18 or 19 wherein the sheets comprise linear bond regions, such as welds, wherein the linear bond regions extend between the apertures bounding unbonded regions of the sheets so that when fluid pressure is applied between the sheets the unbonded regions form the pillars .

21. The robot of any of claims 17 to 20 wherein the scaffold comprises a first fluid port, arranged for supplying inflation fluid to the scaffold and carries a second fluid port for supplying inflation fluid to the soft actuator.

22. The robot of any preceding claim wherein the manipulator comprises a shaft pivotably mounted in the cavity.

23. The robot of claim 22 wherein the shaft is arranged so that an elongate medical device can be disposed through a lumen of the shaft .

24. The robot of claim 23 wherein the shaft carries an extension portion operable to advance in an axial direction from the cavity and to retract, for example wherein the shaft and the extension portion together provide an extensible rigid member.

25. The robot of claim 24 wherein the scaffold carries a bendable coupling arranged to flexibly support a part of the elongate medical device proximal of the shaft.

26. The robot of claim 25 wherein the bendable coupling is configured to allow the elongate medical device to be advanced and retracted.

27. The robot of any of claims 23 to 26 wherein the shaft carries an instrument coupling configured to detachably retain the elongate medical device in a selected axial position relative to the shaft.

28. The robot of claim 27 wherein the instrument coupling couples the elongate medical device to the shaft such that advancement of the elongate medical device causes extension of an extension portion of the shaft.

29. The robot of any preceding claim wherein the soft actuator and the scaffold together are a laminar structure configured to unfurl from the collapsed state in response to inflation.

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