manipulator

Abstract

A manipulator comprises an inner tube, an outer tube and an output member. The outer tube is arranged such that curvature of the inner tube depends on a location of the outer tube relative to the inner tube. The output member is within the inner tube and has a centre line distanced from a centre line of the inner tube such that a location of an end of the output member relative to an input end of the inner tube depends on curvature of the inner tube. The outer tube is configured to be movable relative to the inner tube so as to control the location of the end of the output member relative to the input end of the inner tube.

Description

[0001] MANIPULATOR

[0002] Technical Field

[0003] The present invention relates to a manipulator and a method of controlling a manipulator.

[0004] Background

[0005] A manipulator may be used to impart fine movements. Such a manipulator may be used in, for example, semiconductor manufacturing, micro-surgery and / or cells / tissue manipulation. Manipulators may be used in these or other areas that involve precision engineering.

[0006] A manipulator can use a piezoelectric actuator for making fine movements over a short range. However, such piezoelectric actuators have a non-linear input / output behaviour, have significant hysteresis and suffer from creep. Piezoelectric actuators can also result in complicated modelling and more difficult control of the fine movements.

[0007] For example, CN 102543217 B discloses a macro-micro driven bidimensional integrated micro positioning platform including piezoelectric ceramic actuators.

[0008] It is desirable to provide a manipulator that has a simpler mechanical structure and / or is more compact and / or has input / output behaviour that can be modelled more simply and / or is easier to control and / or is easier to manufacture.

[0009] Summary of Invention

[0010] According to an aspect of the present invention there is provided a manipulator comprising: an inner tube; an outer tube arranged such that curvature of the inner tube depends on a location of the outer tube relative to the inner tube; and an output member within the inner tube and having a centre line distanced from a centre line of the inner tube such that a location of an end of the output member relative to an input end of the inner tube depends on curvature of the inner tube, wherein the outer tube is configured to be movable relative to the inner tube so as to control the location of the end of the output member relative to the input end of the inner tube.

[0011] According to another aspect of the present invention there is provided a method of controlling a manipulator, the method comprising: moving an outer tube relative to an inner tube such that curvature of the inner tube changes depending on a location of the outer tube relative to the inner tube; wherein an output member of the manipulator is within the inner tube and distanced from a centre line of the inner tube such that a location of an end of the output member relative to an input end of the inner tube depends on the curvature of the inner tube.

[0012] Drawings

[0013] The present invention will be described by way of example only with reference to the accompanying drawings.

[0014] Figure 1 is a schematic view of a manipulator.

[0015] Figure 2 is a schematic diagram illustrating a function of the manipulator of Figure 1.

[0016] Figure 3 is a schematic view of the manipulator of Figure 1 comprising carriages on a guide rail.

[0017] Figure 4 is a schematic diagram of the inner tube of the manipulator of Figure 1.

[0018] Figure 5 is a schematic view of the manipulator of Figure 3 comprising motors.

[0019] Detailed description

[0020] Figure 1 shows a manipulator 10 according to an embodiment of the invention. As shown in Figure 1, the manipulator 10 comprises an inner tube 11. The inner tube 11 is elongate. The inner tube 11 is flexible such that the inner tube 11 can bend. The inner tube 11 may have a curvature. The curvature of the inner tube 11 may vary during use of the manipulator 10. The inner tube 11 defines a channel through the inner tube 11. As shown in Figure 1, the diameter of the inner tube 11 may be substantially constant throughout the length of the inner tube 11.

[0021] The inner tube 11 has a centre line 14. The centre line 14 is a geometrical centre of the channel defined by the inner tube 11. As shown in Figure 1, the channel may be substantially circular in cross-section.

[0022] The inner tube 11 may comprise an elastic material. The inner tube 11 may comprise a metal such as nickel, titanium or an alloy such as nickel titanium (also known as nitinol). Alternatively, the inner tube 11 may comprise a plastic. As shown in Figure 1, the manipulator 10 may comprise an outer tube 12. The outer tube 12 may surround the inner tube 11 when viewed along a direction of elongation of the inner tube 11. The outer tube 12 may extend along part of the length of the inner tube 11. The outer tube 12 may be a sleeve around the inner tube 11.

[0023] The curvature of the outer tube 12 may be different from the curvature of the inner tube 11 where the outer tube 12 overlaps the inner tube 11. A motion is actuated when the outer tube 12 moves relative to the inner tube 11 such that the overlap between the outer tube 12 and the inner tube 11 changes.

[0024] The outer tube 12 may be arranged such that the curvature of the inner tube 11 depends on a location of the outer tube 12 relative to the inner tube 11. For example, as shown in Figure 1, the inner tube 11 may have a curved shape when its shape is not restricted by the outer tube 12. For example, during manufacture of the inner tube 11, the inner tube 11 may be formed to have a curved shape. When the outer tube 12 is positioned over a curved portion of the inner tube 11, the outer tube 12 may constrain the inner tube 11. The outer tube 12 may cause the curvature of the inner tube 11 to reduce.

[0025] The outer tube 12 may have a certain bending stiffness. When the outer tube 12 slides along inner tube 11, the outer tube 12 can cause the inner tube 11 (i.e. the overlapped section of the inner tube 11) to exhibit a reduced curvature.

[0026] The outer tube 12 may have a greater stiffness than the inner tube 11. For example, the outer tube 12 may be substantially rigid. Alternatively, the outer tube 12 may have a lesser stiffness than the inner tube 11. Alternatively, the outer tube 12 may have a similar (e.g. equal) stiffness to the inner tube 11. By selecting the relative bending stiffnesses of the inner tube 11 and the outer tube 12, the stroke and / or resolution of the micro-motion may be controlled.

[0027] The outer tube 12 may comprise a metal such as nickel or titanium or an alloy such as nitinol. Alternatively, the outer tube 12 may comprise a polymer.

[0028] As shown in Figure 1, the manipulator 10 may comprise an output member 13. The output member 13 may comprise an end effector. During use of the manipulator 10, the output of the manipulator 10 may be movement of the output member 13. As shown in Figure 1, the output member 13 comprises an end 15. The end 15 of the output member 13 may move during use of the manipulator 10. The manipulator 10 may be configured to output controlled movement of the end 15 of the output member 13. The output member 13 may comprise a rod. As shown in Figure 1, the output member 13 may extend along the length of the inner tube 11. The output member 13 is within the inner tube 11. As shown in Figure 1, part of the output member 13 may protrude beyond an input end 16 of the inner tube 11. The output member 13 may be located only partially within the inner tube 11.

[0029] As shown in Figure 1, the output member 13 may be distanced from the centre line 14 of the inner tube 11. The output member 13 may have its own centre line 17 corresponding to the geometrical centre of the output member 13 along the length of the output member 13. As shown in Figure 1, the centre line 17 of the output member 13 is distanced from the centre line 14 of the inner tube 11. As shown in Figure 1, the offset (i.e. distance) between the centre line 14 of the inner tube 11 and the centre line 17 of the output member 13 may be greater than the radius of the output member 13. As such, the centre line 14 of the inner tube 11 may be outside of the output member 13. Alternatively, the offset between the centre line 14 of the inner tube 11 and the centre line 17 of the output member 13 may be less than the radius of the output member 13. The centre line 14 of the inner tube 11 may be within the output member 13.

[0030] The location of the end 15 of the output member 13 relative to the input end 16 of the inner tube 11 depends on curvature of the inner tube 11. This is because of the offset between the centre line 17 of the output member 13 and the centre line 14 of the inner tube 11.

[0031] Figure 2 is a schematic diagram illustrating use of the manipulator 10 shown in Figure 1. Figure 2 shows two different states of the manipulator 10. A first state is shown with the inner tube 11, the outer tube 12 and the output member 13 in dashed lines. A second state is shown with the inner tube 11, the outer tube 12 and the outer member 13 in solid lines.

[0032] In the first state, the inner tube 11 has a pre-curved section 28 and a straight section 29. In the first state, the outer member 12 is located along the straight section 29. The transition between the pre-curved section 28 of the inner tube 11 and the straight section 29 of the inner tube 11 is indicated by the transition 20 shown in Figure 2. Optionally, the pre-curved section 28 of the inner tube 11 is substantially planar. This means that the shape of the inner tube 11 is within the x-y plane shown in Figure 2. The outer member 12 is located such that the curvature of the pre-curved section 28 of the inner member is unaffected by the outer member 12. In the first state, the end 15 of the output member 13 protrudes from the input end 16 of the inner tube 11 by a first distance qi.

[0033] As shown in Figure 2, in the second state the outer tube 12 is moved relative to its position in the first state. In the second state, the outer tube 12 surrounds the inner tube 11 along part of the pre-curved section 28 of the inner tube 11. The outer tube 12 reduces the curvature of the inner tube 11 in at least part of the pre-curved section 28 of the inner tube 11. For example, Figure 2 shows that the angle of the centre line 14 is reduced to 9 relative to the centre line 14 along the straight section 29 of the inner tube 11.

[0034] As shown in Figure 2, the centre line 17 of the output member 13 is offset from the centre line 14 of the inner tube 11 by an offset distance Ar. As a result of the offset, the extent by which the end 15 of the output member 13 protrudes from the input end 16 of the inner tube 11 varies depending on the curvature of the inner tube 11. As shown in Figure 2, the output member 13 may be located at an inner side of the curve of the inner tube 11 relative to the centre line 14. As a result, as the inner tube 11 straightens, the end 15 of the output member 13 protrudes less from the input end 16 of the inner tube 11. As shown in Figure 2, in the second state the end 15 of the output member 13 protrudes from the inner tube 11 by a second distance q2.

[0035] Between the first state and the second state, the outer tube 12 is moved. As a result of the movement of the outer tube 12, the end 15 of the output member 13 is moved by a distance Aq. As shown in Figure 2, the distance by which the outer tube 12 is moved may be greater than the distance by which the end 15 of the output member 13 is moved as a result. The manipulator 10 may be configured to convert a greater translational movement of the outer tube 12 into a lesser movement of the output member 13. The manipulator 10 may be expected to achieve greater accuracy of control of fine movements.

[0036] The manipulator 10 may be configured to de-amplify motion. For example, a millimetre-level input (i.e. movement of the outer tube 12 by millimetres) may be scaled down to a micrometre-level output (i.e. a change in position of the end 15 of the output member 13 by micrometres).

[0037] The manipulator 10 may have a simpler mechanical structure compared to a piezoelectric-based micro-motion device. The manipulator 10 may have a more compact size than a piezoelectric-based micro-motion device. The manipulator 10 may have a simpler input / output behaviour compared to a piezoelectric-based micro-motion device. For example, the input / output behaviour may be substantially linear. For example, the manipulator 10 may be arranged such that the ratio between the input motion of the outer tube 12 and the output motion of the end 15 of the output member 13 is substantially constant. The manipulator 10 may be expected to allow for a simpler mathematical model compared to a piezoelectric-based micro-motion device. The manipulator 10 may allow for a simpler controller design. For example, the controller design may be based on well- developed traditional motor control algorithms such as a proportional-integral-derivative (pid) control design. The manipulator 10 may be expected to allow for a lower cost manufacture compared to a piezoelectric-based micro-motion device.

[0038] It is not essential for the output member 13 to be located at an inner side of the curve compared to the centre line 14 of the inner tube 11. In an alternative arrangement, the output member 13 may be at an outer side of the curve relative to the centre line 14 of the inner tube 11. As the curvature of the inner tube 11 is reduced, the end 15 of the output member 13 may protrude further from the input end 16 of the inner tube. The inner side of the curve has a smaller radius of curvature than the curvature of the centre line 14 of the inner tube 11. The outer side of the curve has a larger radius of curvature than the curvature of the centre line 14 of the inner tube 11.

[0039] As shown in Figure 1 and Figure 2, the output member 13 may be arranged to project from the input end 16 of the inner tube 11 by an extent that depends on the curvature of the inner tube 11. However, it is not essential for the output member 13 to project from the inner tube 11. In an alternative arrangement, the end 15 of the output member 13 may be within the inner tube 11. The extent by which the input end 16 of the inner tube 11 protrudes further beyond the end 15 of the output member 13 may depend on the curvature of the inner tube 11. In an alternative arrangement, the end 15 of the output member 13 may project beyond the inner tube 11 for some curvatures of the inner tube 11 and may not project beyond the input end 16 of the inner tube 11 for other levels of curvature of the inner tube 11.

[0040] The manipulator 10 may comprise a positioner within the inner tube 11. The positioner may be configured to distance the centre line 17 of the output member 13 from the centre line 14 of the inner tube 11. For example, as shown in Figure 1, the positioner may comprise one or more positioner rods 18. Figure 1 shows three positioner rods 18. Figure 4 schematically shows in cross-section the inner tube 11 of the manipulator 10 shown in Figure 1. Figure 4 shows the three positioner rods 18. The presence of the positioner rods 18 cause the output member 13 to be moved away from the centre of the inner tube 11. As shown in Figure 1 and Figure 4, for example, the output member 13 may be a rod. The output member 13 may be substantially structurally similar to the positioner rods 18. For example, four initially straight super-elastic nitinol rods may be eccentrically arranged within and guided by the inner tube 11. As shown in Figure 1, the output member 13 and / or the positioner rods 18 may traverse the inner tube 11 from its input end 16 to its termination end 19.

[0041] However, it is not essential for the positioner to comprise one or more positioner rods 18. In an alternative arrangement the positioner comprises a catheter. For example the catheter may be fitted tightly within the inner tube 11. The catheter may comprise a channel for accommodating the output member 13. The catheter may be arranged such that the channel is located such that its centre line is offset from the centre line 14 of the inner tube 11. Apart from the channel, the catheter may substantially fill the inner tube 11. The catheter may be secured to the inner tube 11.

[0042] Optionally, the output member 13 is secured to the inner tube 11 at a securing position. The securing position is distanced from the input end 16 of the inner tube 11 and from the end 15 of the output member 13. For example, the output member 13 may be secured relative to the inner tube 11 at the termination end 19 of the inner tube 11. The termination end 19 and the input end 16 of the inner tube 11 are at opposite ends of the inner tube 11. The output member 13 may be secured directly to the inner tube 11. Alternatively, the output member 13 may be secured to the inner tube 11 indirectly (e.g. via an intermediate member).

[0043] Optionally, the positioner is secured to the inner tube 11. For example the positioner may be secured to the inner tube 11 at a securing position.

[0044] Away from the securing position, the output member 13 may be configured such that movement is possible between the output member 13 and the inner tube 11 along the direction of elongation of the inner tube 11. This movement allows the end 15 of the output member 13 to move relative to the input end 16 of the inner tube 11 as the curvature of the inner tube 11 changes. In general, a greater length between the securing position and the end 15 of the output member 13 may allow for a greater movement of the end 15 of the output member 13 as the curvature of the inner tube 11 is controlled.

[0045] The output member 13 may be secured to the inner tube 11 by a tight fitting. For example, a fitting member may be located in the middle of the output member 13 and the positioner rods 18 so as to cause a tight fit of the fitting member and the output member 13 and the positioner rods 18 at the securing position. Additionally or alternatively, the output member 13 may be secured to the inner tube 11 by an adhesive. Additionally or alternatively, the output member 13 may be secured to the inner tube 11 by an external member such as a clamp.

[0046] Figure 3 is a schematic view of the manipulator 10 of Figure 1 comprising a frame. The frame is configured to support the inner tube 11, the outer tube 12 and the output member 13. For example, as shown in Figure 3 the frame may comprise a guide rail 30 and one or more carriages 31-33. The carriages 31-33 are configured to slide along the guide rail 30. The guide rail 30 is configured to support the carriages 31-33. As shown in Figure 3, the guide rail 30 may be substantially linear. The carriages 31-33 are configured to translate substantially linearly along the guide rail 30.

[0047] As shown in Figure 3, the frame may comprise an output carriage 34. Motion of the output carriage 34 along the guide rail 30 is shown by the double ended arrow 24 shown in Figure 3. The output member 13 may be secured to the output carriage 34. For example, the output member 13 may be clamped to the output carriage 34. As shown in Figure 3, the manipulator 10 may comprise a clamp 44 configured to clamp the output member 13 to the output carriage 34. The clamp 44 may be configured to clamp the output member 13 at or near the end 15 of the output member 13. During use of the manipulator 10, the movement of the end 15 of the output member 13 may result in movement of the output carriage 34 along the guide rail 30. The output carriage 34 may be configured to support a device to be actuated by the output member 13. For example, a pipette may be actuated by the motion of the output member 13.

[0048] As shown in Figure 3, the frame may comprise an outer tube carriage 32. The outer tube 12 is secured to the outer tube carriage 32. For example, as shown in Figure 3 one end of the outer tube 12 may be secured to the outer tube carriage 32. When the outer tube carriage 32 moves along the guide rail 30, the outer tube 12 is caused to move relative to the guide rail 30. Motion of the outer tube carriage 32 is illustrated by the double ended arrow 22 shown in Figure 3.

[0049] As shown in Figure 3, the outer tube carriage 32 may comprise a fixture 42. The fixture 42 is configured to secure the outer tube 12 to the output carriage 32.

[0050] As shown in Figure 3, the frame may comprise an inner tube carriage 33. The inner tube 11 is secured to the inner tube carriage 33. When the inner tube carriage 33 moves along the guide rail 30, the inner tube 11 moves relative to the guide rail 30. Motion of the inner tube carriage 33 along the guide rail 30 is shown by the double ended arrow 23 shown in Figure 3.

[0051] As shown in Figure 3, the inner tube carriage 33 may comprise a fixture 43 configured to secure the inner tube 11 to the inner tube carriage 33. As shown in Figure 3, the fixture 43 may be configured to secure the input end 16 of the inner tube 11 to the inner tube carriage 33. Alternatively, an intermediate portion of the inner tube 11 may be secured to the inner tube carriage 33.

[0052] When the outer tube carriage 33 is moved along the guide rail 30 while the inner tube carriage 33 remains stationary relative to the guide rail 30, then the outer tube 12 is caused to move relative to the inner tube 11. As a result, the curvature 21 of the inner tube 11 is controlled.

[0053] Optionally, the frame comprises a support carriage 31. The support carriage 31 is configured to move along the guide rail 30. As shown in Figure 3, the support carriage 31 is configured to support the inner tube 11 and / or the outer tube 12. As shown in Figure 3, the support carriage 31 may comprise a fixture 41. The fixture 41 may comprise an aperture configured to accommodate the inner tube 11 and the outer tube 12. The support carriage 31 may be arranged such that the outer tube 12 can move through the aperture relative to the support carriage 31. The inner tube 11 may be fixed to the inner tube carriage 33. The inner tube carriage 33 may be fixed to the support carriage 31 by the connectors 45 (described below). The inner tube 11 may have a fixed position relative to the support carriage 31.

[0054] As shown in Figure 3, the frame may comprise one or more connectors 45. The connectors 45 are configured to connect the support carriage 31 to the inner tube carriage 33. During use of the manipulator 10, the inner tube carriage 33 may be driven along the guide rail 30. When the inner tube carriage 33 moves, the support carriage 31 may be caused to move together with the inner tube carriage 33. The connectors 45 may be configured to secure the support carriage 31 relative to the inner tube carriage 33.

[0055] When the outer tube carriage 32 is driven while the inner tube carriage 33 remains stationary, then the outer tube 12 may slide through the aperture of the fixture 41 of the support carriage 31. The support carriage 31 may remain stationary while the inner tube carriage 33 remains stationary.

[0056] Figure 5 is a schematic view of the manipulator 10 comprising an actuator arrangement. The actuator arrangement is configured to actuate the outer tube 12 to move relative to the inner tube 11. By actuating the outer tube 12 to move relative to the inner tube 11, the end 15 of the output member 13 may be controlled to move with fine movements at a high level of accuracy.

[0057] Optionally, the actuator arrangement is configured to actuate the inner tube 11 and the outer tube 12 to move together. When the inner tube 11 and the outer tube 12 move together, then the output member 13 may move together with the inner tube 11 and the outer tube 12. Movement of the inner tube 11 together with the outer tube 12 may be used to make coarser movements of the output member 13. For example, by moving the inner tube carriage 33 and the outer tube carriage 32 by a certain distance, then the end 15 of the output member 13 may move that same certain distance in the direction of the guide rail 30.

[0058] Optionally, the manipulator 10 is arranged such that actuation of the outer tube 12 relative to the inner tube 11 causes finer changes to the location of the end 15 of the output member 13 relative to the input end 16 of the inner tube 11 compared to movement of the output member 13 caused by actuation of the inner tube 11 and the outer tube 12 to move together. When macro motion is desired, then the inner tube 11 may be moved together with the outer tube 12 so as to cause movement of the output member 13. When micro motion is required, then the outer tube 12 may be moved relative to the inner tube 11 so as to cause movement of the output member 13 due to changes in curvature of the inner tube 11.

[0059] The manipulator 10 is expected to achieve accurate control of motions for both large and small scales.

[0060] The actuator arrangement may be configured to actuate the inner tube 11 and the outer tube 12 to move together in a direction parallel to the direction of elongation of the output member 13 (in the region at the end of the output member 13). This may be the direction parallel to the guide rail 30 in the example shown in the Figures.

[0061] Optionally, the outer tube 12 has no pre-curvature. That is, the outer tube 12 may be substantially straight when not undergoing external pressures. Where the outer tube 12 overlaps the inner tube 11, the outer tube 12 may be caused to curve due to the curvature of the inner tube 11. The overlapping section may be a curve with a lesser degree of curvature compared to the curved inner tube 11 that is not overlapped by the outer tube 12.

[0062] The manipulator comprises a hybrid continuum structure. The structure is a hybrid in that it is a combination of a many-backbone continuum architecture and a concentric tube continuum structure.

[0063] As shown in Figure 5, optionally the actuator arrangement comprises one or more motors 62, 63. The motors 62, 63 may be brushless DC motors, for example. As shown in Figure 5, optionally the actuator arrangement comprises one or more transmissions. For example, the transmissions may comprise lead screw-nuts 72, 73. A first motor 62 may be configured to actuate the outer tube carriage 32 via a first lead screw-nut 72. A second motor 63 may be configured to actuate the inner tube carriage 33 via a second lead screw- nut 73. Each motor may comprise a motor driver. As shown in Figure 5, in an embodiment the manipulator 10 comprises one or more limit switches 52, 53.

[0064] Optionally, each motor 62, 63 comprises a planetary gearbox and an absolute encoder. The motor driver may be configured to run a field-oriented-control algorithm to operate the motors 62, 63 in a current-loop mode. The transmissions (e.g. the lead screw- nuts 72, 73) may be configured to convert the motor rotation to linear actuation. The limit switches 52, 53 may be configured to perform homing operations. For example, the limit switches 52, 53 may be configured to return the respective carriages 32, 33 to respective home positions along the guide rail 30.

[0065] In an embodiment the manipulator 10 comprises a controller (not shown). The controller may be configured to control actuation of the inner tube 11 and the outer tube 12. For example, the controller may be configured to control the motors 62, 63 so as to control actuation of the inner tube carriage 33 and the outer tube carriage 32.

[0066] The controller may comprise an embedded controller platform configured to interface with the motor drivers of the motors 62, 63. The controller may be configured to send control signals to the motors 62, 63. The controller may be configured to receive data signals providing feedback (e.g. indicating the current locations of the carriages along the guide rail).

[0067] Optionally, a semiconductor manufacturing device comprises the manipulator 10. Optionally, a micro-surgery device comprises the manipulator 10. Optionally, a cell / tissue manipulator comprises the manipulator 10.

[0068] Embodiments of the invention have been described by way of example only. Various modifications may be made to the embodiments as described. For example, optionally the input ends of the tubes are glued within 3D-printed nylon fixtures. The fixtures may be installed on mechanical parts such that they are configured to slide with the carriages along the guide rail 30.

[0069] The controller may be configured to receive data signals from the motor drivers of the motors 62, 63 via a Controller Area Network (CAN).

[0070] The lead screw-nuts 72, 73 may be trapezoidal. The lead screw-nuts 72, 73 may have a pitch within a range of from about 0.5 mm to about 5 mm. For example, the first lead screw-nut 72 may have a pitch of about 1 mm. The second lead screw-nut 73 may have a pitch of about 2 mm.

[0071] In an embodiment, the manipulator 10 may be calibrated. Experiments may be performed so as to determine what extent of translational input movement is appropriate for a desired level of output movement of the end 15 of the output member 13. Calibration data may be used by the controller. The controller may be configured to store the calibration data.

[0072] In the arrangements shown in the drawings, the manipulator 10 comprises one output member 13 (i.e. only one output member 13). In an alternative arrangement, the manipulator 10 may comprise a plurality of output members. For example, the positioner rod 18 opposite the output member 13 within the inner tube 11 may be arranged as a second output member. The ends of both output members may be secured to a device to be rotated, for example. Alternatively, rotation of an output may be achieved by a single output member 13.

Claims

Claims1. A manipulator comprising: an inner tube; an outer tube arranged such that curvature of the inner tube depends on a location of the outer tube relative to the inner tube; and an output member within the inner tube and having a centre line distanced from a centre line of the inner tube such that a location of an end of the output member relative to an input end of the inner tube depends on curvature of the inner tube, wherein the outer tube is configured to be movable relative to the inner tube so as to control the location of the end of the output member relative to the input end of the inner tube.

2. The manipulator of claim 1, wherein the output member is arranged to project from the input end of the inner tube by an extent that depends on the curvature of the inner tube.

3. The manipulator of claim 1 or 2, comprising within the inner tube a positioner configured to distance the centre line of the output member from the centre line of the inner tube.

4. The manipulator of claim 3, wherein the positioner comprises one or more positioner rods.

5. The manipulator of any preceding claim, wherein the output member is secured to the inner tube at a securing position, the securing position being distanced from the input end of the inner tube and the end of the output member.

6. The manipulator of claim 5, wherein the securing position is at a termination end of the inner tube, the termination end and the input end being at opposite ends of the inner tube.

7. The manipulator of any preceding claim, comprising: an actuator arrangement configured to actuate the outer tube to move relative to the inner tube.

8. The manipulator of claim 7, wherein the actuator arrangement is configured to actuate the inner tube and the outer tube to move together.

9. The manipulator of claim 8, arranged such that actuation of the outer tube relative to the inner tube causes finer changes to the location of the end of the output member relative to the input end of the inner tube compared to movement of the output member caused by actuation of the inner tube and the outer tube to move together.

10. The manipulator of claim 8 or 9, arranged such that the actuator arrangement is configured to actuate the inner tube and the outer tube to move together in a direction parallel to a direction of elongation of the output member at the end of the output member.

11. The manipulator of any preceding claim, comprising: a frame configured to support the inner tube, the outer tube and the output member.

12. The manipulator of claim 11, wherein the frame comprises: a guide rail; andone or more carriages configured to slide along the guide rail.

13. The manipulator of claim 12, wherein the one or more carriages comprises an output carriage to which the output member is secured.

14. The manipulator of claim 12 or 13, wherein the one or more carriages comprises an outer tube carriage to which the outer tube is secured.

15. The manipulator of any of claims 12-14, wherein the one or more carriages comprises an inner tube carriage to which the inner tube is secured.

16. The manipulator of any preceding claim, wherein the outer tube has a different curvature from the inner tube where the outer tube overlaps the inner tube.

17. The manipulator of any preceding claim, wherein the outer tube has a greater stiffness than the inner tube.

18. The manipulator of any of claims 1-16, wherein the outer tube has a lesser stiffness than the inner tube19. A method of controlling a manipulator, the method comprising: moving an outer tube relative to an inner tube such that curvature of the inner tube changes depending on a location of the outer tube relative to the inner tube; wherein an output member of the manipulator is within the inner tube and distanced from a centre line of the inner tube such that a location of an end of the output member relative to an input end of the inner tube depends on the curvature of the inner tube.

Images