NL2028414B1 - Steerable instrument for endoscopic or invasive applications - Google Patents

Abstract

A cylindrical instrument has a first tube (1601; 1619), a second tube (1620) surrounding the first tube (1601; 1619), and a third tube (1602; 1621) surrounding the second tube 5 (1620). The instrument has a deflectable tip section (1613), a steering section (1618), a flexible body section (1615) between the tip section (1613) and the steering section (1618), a length compensation section (1617), and one or more steering wires (16(i)) extending from the steering section (1618) to the tip section (1613) such that the tip section (1613) can be deflected by moving the one or more steering wires (16(i)) in a longitudinal direction 10 of the cylindrical instrument. The cylindrical instrument has a Bowden cable arrangement for each steering wire (16(i)) inside the body section (1615) and the length compensation section (1617), each Bowden cable arrangement has a steering wire (16(i)) surrounded by steering wire guiding portions. The steering wires (16(i)) and the steering wire guiding portions are portions of the first tube (1619), the second tube (1620), or the third tube 15 (1621). [Fig. 16]

Description

Steerable instrument for endoscopic or invasive applications Field of the invention

[0001] The present invention relates to a steerable instrument for endoscopic and/or invasive type of applications, such as in surgery. The steerable instrument according to the invention can be used in both medical and non-medical applications. Examples of the latter include inspection and/or repair of mechanical and/or electronic hardware at locations that are difficult to reach. Hence, terms used in the following description such as endoscopic application or invasive instrument, must be interpreted in a broad manner. Background art

[0002] Transformation of surgical interventions that require large incisions for exposing a target area into minimal invasive surgical interventions, i.e. requiring only natural orifices or small incisions for establishing access to the target area, is a well-known and ongoing process. In performing minimal invasive surgical interventions, an operator such as a physician, requires an access device that is arranged for introducing and guiding invasive instruments into the human or animal body via an access port of that body. In order to reduce scar tissue formation and pain to a human or animal patient, the access port is preferably provided by a single small incision in the skin and underlying tissue. In some applications, a natural orifice of the body can be used as an entrance. Furthermore, the access device preferably enables the operator to control one or more degrees of freedom that the invasive instruments offer. In this way, the operator can perform required actions at the target area in the human or animal body in an ergonomic and accurate manner with a reduced risk of clashing of the instruments used.

[0003] Surgical invasive instruments and endoscopes are well-known in the art. Both the invasive instruments and endoscopes can comprise a steerable tube that enhances its navigation and steering capabilities. Such a steerable tube may comprise a proximal end part including at least one flexible zone, a distal end part including at least one flexible zone, and an intermediate part, wherein the steerable tube further comprises a steering arrangement that is adapted for translating a deflection of at least a part of the proximal end part relative to the intermediate part into a related deflection of at least a part of the distal end part. Alternatively, the distal flexible zone may be steered by a robotic instrument arranged at the proximal end of the steerable instrument.

[0004] Steerable invasive instruments may comprise a handle that is arranged at the proximal end part of the steerable tube for steering the tube and/or for manipulating a tool that is arranged at the distal end part of the steerable tube. Such a tool can for example be a camera, a manual manipulator, e.g. a pair of scissors, forceps, or manipulators using an energy source, e.g. an electrical, ultrasonic or optical energy source.

[0005] Furthermore, such a steerable tube may comprise a number of co-axially arranged cylindrical elements including an outer cylindrical element, an inner cylindrical element and one or more intermediate cylindrical elements depending on the number of flexible zones in the proximal and distal end parts of the tube and the desired implementation of the steering members of the steering arrangement, i.e. all steering members can be arranged in a single intermediate cylindrical element or the steering members are divided in different sets and each set of steering members is arranged, at least in part, in a different or the same intermediate cylindrical element. In most prior art devices, the steering arrangement comprises conventional steering cables with, forinstance, sub 1 mm diameters as steering members, wherein the steering cables are arranged between related flexible zones at the proximal and distal end parts of the tube. Other steering units at the proximal end, like ball shaped steering units or robot driven steering units, may be applied instead.

[0006] However, as steering cables have many well-known disadvantages, for some applications one may want to avoid them and to implement the steering members by one or more sets of steering wires that form integral parts of the one or more intermediate cylindrical elements. Each of the intermediate cylindrical elements including the steering wires can be fabricated either by using a suitable material addition technique, such as injection molding or plating, or by starting from a tube and then using a suitable material removal technique, such as laser cutting, photochemical etching, deep pressing, conventional chipping techniques such as drilling or milling or high-pressure water jet cutting systems. Steering wires manufactured in that way are, then, implemented as longitudinal strips resulting from the tube material, and can be used as pulling/pushing wires. Of the aforementioned material removal techniques, laser cutting is very advantageous as it allows a very accurate and clean removal of material under reasonable economic conditions.

[0007] The inner and outer cylindrical elements may be manufactured from tubes too. These tubes should be flexible at locations where the distal end, and possibly the proximal end too, of the instrument is bendable. Also at other locations where the instrument should be flexible, the inner and outer cylindrical elements should be flexible. This can be implemented by providing the inner and outer cylindrical elements with hinges at these flexible locations. Such hinges may result from (laser) cutting predetermined patterns in the tube. Many different patterns are known from the prior art. Which pattern to use depends on design requirements at the location concerned including but not limited to the required bending angle, bending flexibility, longitudinal stiffness, and radial stiffness.

[0008] Further details regarding the design and fabrication of the abovementioned steerable tube and the steering arrangement thereof have been described for example in WO 2009/112060 A1, WO 2009/127236 A1, US 13/160,949, and US 13/548,935 of the applicant, all of which are hereby incorporated by reference in their entirety.

[0009] As is known from for example a flexible endoscopic instrument with a steerable tip, flexible invasive steerable instruments can show performance flaws with respect to steerable tip control. When such a flexible instrument is inserted into a body through a curved channel, either an endoscope or a natural body lumen, bending of the instrument causes displacement of the longitudinal tip steering elements. Because in conventionally built instruments the steering elements, e.g. wires, are fixed to a steering device, like a handle, at the proximal side and to the steerable tip at the distal side, movement of the steering wires will result in deflection of the steering device and or deflection of the steerable tip. This causes the problem that when the instrument is advanced through a narrow curved channel, and when one holds the steering device in a fixed position, the tip will deflect uncontrollable during advancement and can either lock up in, for example, a narrow endoscope working channel or it can damage tissue in for example a soft tissue natural body lumen like the lung bronchi or the esophagus.

[0010] Another problem is that when the instrument passed the entrance channel and the instrument tip reached the targeted operation site, the tip deflection does not match the steering device deflection anymore. So a neutral position of the steering device does not result in a neutral position of the steerable tip. This offset does adversely affect eye-hand coordination of the user.

[0011] Yet another problem with flexible steerable instruments is that when the tip is steered with the steering elements, also the body will be steered by the steering elements because the whole body, mechanically, behaves like a steerable tip. The ratio of deflection between the body and tip deflection merely depends on the bending stiffness of the body and the tip. The stiffer the body is with respect to the stiffness of the tip, the more the tip will be steered. In practice, the tip is more flexible than the body, but still there is a tendency that steering the tip will result also in body deflection which on its turn will result in side forces on the surrounding channel that tends to keep the instrument body in a certain curvature. If the surrounding channel exists of soft body tissue, this is a strongly unwanted instrument behaviour, since the side forces might damage the surrounding tissue. Also body movement might disturb the positioning of the steerable tip at the target site and makes accurate and predictable tip steering more difficult.

[0012] A partial solution to this problem that addresses the problem of unwanted tip steering due to bending of the instrument body is described in WO2014/011049. This solution describes an instrument in which the steering wires can be de-coupled from the steering device and the ends of these steering wires and hence the instrument tip can move freely when the instrument is advanced through a curved entrance path. Once the instrument tip passed the entrance channel and is at the targeted operation site, the steering wires are re-coupled to the steering device and the instrument tip can now be steered. The disadvantages of this solution are that the instrument is mechanically more complex and requires more parts to build. Another disadvantage is that the operator has to follow a certain procedure for passing the curved entrance channel with which he can make mistakes or which he might forget to perform. Yet another disadvantage is that the problem of body steering (side forces) is still not addressed.

[0013] Prior art solutions have in common that they are built from specially fabricated tubings, coils and machined parts and that assembly of such instruments is usually a time consuming and difficult process. Also tolerances of the separate parts add up in the assembly and can be the cause of a wide spread in for example instrument performance, often requiring an individual calibration of each instrument.

Summary of the invention

[0014] It is an object of the invention to provide a steerable instrument for endoscopic and/or invasive type of applications where at least one of the above mentioned problems are solved or at least reduced.

[0015] To that end, independent aspects of the invention are defined in independent claims whereas dependent claims relate to advantageous embodiments.

[0016] Some embodiments comprise a Bowden cable arrangement.

[0017] In this application, the terms “proximal” and “distal” are defined with respect to an operator, e.g. a robot or physician that operates the instrument or endoscope. For example, a proximal end part is to be construed as a part that is located near the robot or physician and a distal end part as a part located at a distance from the robot or physician, i.e., in the area of operation.

[0018] In many embodiment, the invention comprises an instrument having the same and improved performance as prior solutions, but which is built with significantly less separate parts and significantly less assembly effort. All the necessary elements to construct a steerable instrument, including a Bowden-cable construction may be integrally manufactured, in a largely pre-assembled state, from a number of tubes. The only remaining assembly steps consist of sliding the tubes into each other and attach the tubings to each other in the required places. The preassembled parts can be made in a tube wall by material deposition processes like 3D printing or plating techniques. Preferably the preassembled parts can be made by material removal processes from a solid wall metal or plastic tube (stainless steel, cobalt chromium alloys, super- elastic alloys like nitinol, etc). The material removal processes that can be used are for example conventional chipping processes, water jet cutting, etching and preferably laser cutting processes.

[0019] Therefore, those embodiments of this invention enable a significant reduction of manufacturing costs of such instruments and therefor the costs of an intervention in which these instruments are used. It even becomes commercially viable to use these instruments only once, and then throw them away. This increases the safety of an intervention because one can now use new instruments instead of pre-used and re-sterilized instruments that are known to have a 10% risk of post procedural complication due to contaminating or infecting the patient with not properly cleaned or re-sterilized pre-used instruments.

[0020] Another advantage of such an instrument is that by using this integrated way of producing parts in a pre-assembled state, that they always fit to each other and that minimal play between the parts can be achieved. This is especially true when a laser cutting process is used.

The minimal achievable play between two integrally manufactured parts is as low as the width of the used laser beam, which can be as small as 0.01mm. Typically a play of 0.01 to 0.05mm can be obtained easily. The integral fabrication of parts according to the invention therefor is so accurate with respect to fitting of parts and the play between them, that an improved accuracy and repeatability of the instrument's functional performance is ensured.

Brief description of the drawings

[0021] Further features and advantages of the invention will become apparent from the description of the invention by way of non-limiting and non-exclusive embodiments. These 5 embodiments are not to be construed as limiting the scope of protection. The person skilled in the art will realize that other alternatives and equivalent embodiments of the invention can be conceived and reduced to practice without departing from the scope of the present invention.

Embodiments of the invention will be described with reference to the figures ofthe accompanying drawings, in which like or same reference symbols denote like, same or corresponding parts, and in which:

[0022] Figure 1 shows a schematic cross sectional view of an invasive instrument assembly having one bendable distal end portion and one proximal end portion which controls the bending of the bendable distal end portion by means of strips cut out in a cylindrical element.

[0023] Figure 2 shows a schematic overview of three cylindrical elements from which the instrument of Figure 1 may be manufactured.

[0024] Figure 3a shows a portion of an intermediate cylindrical element of the instrument of Figures 1 and 2.

[0025] Figure 3b shows an alternative example of an intermediate cylindrical element of such an instrument.

[0026] Figure 4 shows an example intermediate cylindrical element and an inner cylindrical element inserted in the intermediate cylindrical element.

[0027] Figure 5 shows an outside view of a steerable invasive instrument assemble having two steerable bendable distal end portions and two proximal flexible control portions.

[0028] Figure 6 shows an enlarged view of the distal tip of the instrument shown in Figure

5.

[0029] Figure 7 shows a cross section view through the invasive instrument shown in Figure 5.

[0030] Figures 8 and 9 show examples of how the invasive instrument of Figures 5 and 7 can bend.

[0031] Figure 10 shows an alternative embodiment of the invasive instrument shown in Figures 5-9, wherein at least a portion of an intermediate section between the distal end and the proximal end is flexible too.

[0032] Figures 11 and 12 show schematic examples of using an invasive instrument as an endoscopic surgical instrument in which the intermediate section between the distal end and the proximal end is flexible too such that the invasive instrument can be inserted in a natural body canal like the intestinal canal, and the oesophagus.

[0033] Figures 13-15 show prior art instruments with Bowden cable arrangements to compensate steering wire length changes in the body section when the body section bends.

[0034] Figures 16-26, 29 and 30 show instruments with a Bowden cable arrangement in which both steering wires and steering wire guiding elements are manufactured as portions from tubes surrounding one another. In these figures, the Bowden cable arrangements extend radially from a central axis of the instrument. Figure 29 shows a case wherein the Bowden cable arrangement extends radially inward whereas in all other examples it extends radially outward.

[0035] Figure 27 shows a Bowden cable arrangement in which both steering wires and steering wire guiding elements are manufactured as portions from a single tube and are configured such that length compensation movements occur in the tangential direction of the tube.

[0036] Figures 28a, 28b show an embodiment in which portions of steering wires inside the length compensation section as manufactured from a tube are designed such that they can mechanically compensate steering wire length changes in the body section when the body section bends.

[0037] Figures 31a-31¢ show an embodiment in which the length compensation section is implemented by changing the position of the portions of steering wires and steering wire guiding portions inside the length compensation section in the longitudinal direction as controlled by a processor. They also show reaction force compensation.

Description of embodiments

[0038] For the purpose of the present document, the terms cylindrical element and tube may be used interchangeably, i.e., like the term tube a cylindrical element also refers to a physical entity. The invention will be explained with reference to steering wires which are cut from such cylindrical elements and are operative as push and/or pull steering wires to transfer movement of the steering wires at the proximal end of the instrument to the distal end to thereby control bending of one or more flexible distal end portions. However, in some embodiments, the invention can also be implemented with steering wires made in a classic way and not resulting from cutting them out of a tube. In some embodiments, steering wire guiding element portions are also made by cutting them out of one or more tubes. They sense or measure longitudinal length differences of the instrument body walls by means of generating a length displacement at one of their ends. Instruments in which the invention can be applied

[0039] Figures 1, 2, 3a, and 3b are known from WO2009/112060. They are explained in detail because the present invention can be applied in this type of instruments.

[0040] Figure 1 shows a longitudinal cross-section of a prior art steerable instrument comprising three co-axially arranged cylindrical elements, i.e. inner cylindrical element 2, intermediate cylindrical element 3 and outer cylindrical element 4. Suitable materials to be used for making the cylindrical elements 2, 3, and 4 include stainless steel, cobalt-chromium, shape memory alloy such as Nitinol®, plastic, polymer, composites or other materials that can be shaped by material removal processes like laser cutting or EDM. Alternatively, the cylindrical elements can be made by a 3D printing process or other known material deposition processes.

[0041] The inner cylindrical element 2 comprises a first rigid end part 5, which is located at a distal end part 13 of the instrument, a first flexible part 6, an intermediate rigid part 7 located at an intermediate part 12 of the instrument, a second flexible part 8 and a second rigid end part 9, which is located at a proximal end part 11 of the instrument.

[0042] The outer cylindrical element 4 also comprises a first rigid end part 17, a first flexible part 18, an intermediate rigid part 19, a second flexible part 20 and a second rigid end part 21.

The lengths of the parts 5, 6, 7, 8, and 9, respectively, of the cylindrical element 2 and the parts 17, 18, 19, 20, and 21, respectively, of the cylindrical element 4 are, preferably, substantially the same so that when the inner cylindrical element 2 is inserted into the outer cylindrical element 4, these different respective parts are longitudinally aligned with each other.

[0043] The intermediate cylindrical element 3 also has a first rigid end part 10 and a second rigid end part 15 which in the assembled condition are located between the corresponding rigid parts 5, 17 and 9, 21 respectively of the two other cylindrical elements 2, 4. The intermediate part 14 of the intermediate cylindrical element 3 comprises one or more separate steering wires 16 which can have different forms and shapes as will be explained below. They are made from the cylindrical element 3 themselves and have the form of a longitudinal strip. In figure 3a, three such steering wires 16 are shown. After assembly of the three cylindrical elements 2, 3 and 4 whereby the element 2 is inserted in the element 3 and the two combined elements 2, 3 are inserted into the element 4 (any other order is possible), at least the first rigid end part 5 of the inner cylindrical element 2, the first rigid end part 10 of the intermediate cylindrical element 3 and the first rigid end part 17 of the outer cylindrical element 4 at the distal end of the instrument are attached to each other, e.g., by means of glue or one or more laser welding spots. In the embodiment shown in figures 1 and 2, also the second rigid end part 9 of the inner cylindrical element 2, the second rigid end part 15 of the intermediate cylindrical element 3 and the second rigid end part 21 of the outer cylindrical element 4 at the proximal end of the instrument are attached to each other, e.g. by means of glue or one or more laser welding spots, such that the three cylindrical elements 2, 3, 4 form one integral unit.

[0044] In the embodiment shown in figure 2 the intermediate part 14 of intermediate cylindrical element 3 comprises a number of steering wires 16 with a uniform cross-section so that the intermediate part 14 has the general shape and form as shown in the unrolled condition of the intermediate cylindrical element 3 in figure 3a. From figure 3a it also becomes clear that the intermediate part 14 is formed by a number of over the circumference of the intermediate cylindrical part 3, possibly equally, spaced parallel steering wires 16. Advantageously, the number of steering wires 16 is at least three, so that the instrument becomes fully controllable in any direction, but any higher number is possible as well. The number of steering wires 16 may, e.g., be six or eight.

[0045] It is observed that the steering wires 16 need not have a uniform cross section across their entire length. They may have a varying width along their length, possibly such that at one or more locations adjacent steering wires 16 are only separated by a small slot resulting from the laser cutting in the cylindrical element 3. These wider portions of the steering wires, then, operate as spacers to prevent adjacent steering wires 16 from buckling in a tangential direction in a pushed state. Spacers may, alternatively, be implemented in other ways.

[0046] An embodiment with spacers is shown in figure 3b which shows two adjacent steering wires 16 in an unrolled condition. In the embodiment shown in figure 3b each steering wire 16 is composed of three portions 61, 62 and 63, co-existing with the first flexible part 6, 18 the intermediate rigid part 7, 19 and the second flexible part 8, 20 respectively. In the portion 62 coinciding with the intermediate rigid portion, each pair of adjacent steering wires 16 is almost touching each other in the tangential direction so that in fact only a narrow slot is present there between just sufficient to allow independent movement of each steering wire. The slot results from the manufacturing process and its width is, e.g., caused by the diameter of a laser beam cutting the slot.

[0047] In the other two portions 61 and 63 each steering wire consists of a relatively small and flexible part 64, 65 as seen in circumferential direction, so that there is a substantial gap between each pair of adjacent flexible parts, and each flexible part 64, 65 is provided with a number of spacers 66, extending in the tangential direction and almost bridging completely the gap to the adjacent flexible part 64, 65. Because of these spacers 66 the tendency ofthe steering wires 16 in the flexible portions of the instrument to shift in tangential direction is suppressed and tangential direction control is improved. The exact shape of these spacers 66 is not very critical, provided they do not compromise flexibility of flexible parts 64 and 65. The spacers 66 may form an integral part with the flexible parts 64, 65 and may result from a suitable laser cutting process too.

[0048] In the embodiment shown in figure 3b the spacers 66 are extending towards one tangential direction as seen from the flexible part 64, 65 to which they are attached. It is however also possible to have these spacers 66 extending to both circumferential directions starting from one flexible part 64, 65. By using this it is either possible to have alternating types of flexible parts 64, 65 as seen along the tangential direction, wherein a first type is provided at both sides with spacers 66 extending until the next flexible part, and a second intermediate set of flexible parts 64, 65 without spacers 66. Otherwise it is possible to have flexible parts with cams at both sides, where as seen along the longitudinal direction of the instrument the cams originating from one flexible part are alternating with spacers originating from the adjacent flexible parts. It is obvious that numerous alternatives are available.

[0049] The production of such an intermediate part is most conveniently done by injection moulding or plating techniques or starting from a cylindrical tube with the desired inner and outer diameters and removing parts of the wall of the cylindrical tube required e.g. by laser or water cutting to end up with the desired shape of the intermediate cylindrical element 3. However, alternatively, any 3D printing method can be used.

[0050] The removal of material can be done by means of different techniques such as laser cutting, photochemical etching, deep pressing, conventional chipping techniques such as drilling or milling, high pressure water jet cutting systems or any suitable material removing process available. Preferably, laser cutting is used as this allows for a very accurate and clean removal of material under reasonable economic conditions. The above mentioned processes are convenient ways as the cylindrical element 3 can be made so to say in one process, without requiring additional steps for connecting the different parts of the intermediate cylindrical element as required in the conventional instruments, where conventional steering cables must be connected in some way to the end parts. The same type oftechnology can be used for producing the inner and outer cylindrical elements 2 and 4 with their respective flexible parts 6, 8, 18 and

20. These flexible parts 6, 8, 18 and 20 can be manufactured as hinges resulting from cutting out any desired pattern from the cylindrical elements, e.g., by using any of the methods described in European patent application 08 004 373.0 filed on 10.03.2008, page 5, lines 15-26, but any other suitable process can be used to make flexible portions.

[0051] It is observed that the instruments shown in figures 4-10 are known from prior art WO2020/214027. Also in these instruments the present invention can be applied.

[0052] Figure 4 shows an exemplary embodiment of longitudinal (steering) elements 16 that have been obtained after providing longitudinal slots 70 to the wall of the intermediate cylindrical element 3 that interconnects proximal flexible zone 14 and distal flexible zone 16 as described above. Here, steering wires 16 are, at least in part, spiralling about a longitudinal axis of the instrument such that an end portion of a respective steering element 16 at the proximal portion of the instrument is arranged at another angular orientation about the longitudinal axis than an end portion of the same steering wire 18 at the distal portion of the instrument. Were the steering wires 18 arranged in a linear orientation, than a bending of the instrument at the proximal portion in a certain plane would result in a bending of the instrument at the distal portion in the same plane but in a 180 degrees opposite directions. This spiral construction of the steering wires 16 allows for the effect that bending of the instrument at the proximal portion in a certain plane may result in a bending of the instrument at the distal portion in another plane, or in the same plane in the same direction. A preferred spiral construction may be such that the end portion of a respective steering element 16 at the proximal portion of the instrument is arranged at an angularly shifted orientation of 180 degrees about the longitudinal axis relative to the end portion of the same steering wire 16 at the distal portion of the instrument. However, e.g. any other angularly shifted orientation, e.g. 90 degrees, is within the scope of this document. The slots 70 are dimensioned such that movement of a steering wire is guided by adjacent steering wires when provided in place in a steerable instrument. However, especially at the flexible zones 13, 14 of the instrument, the width of steering wires 16 may be less to provide the instrument with the required flexibility / bendability at those locations.

[0053] Figure 5 provides a detailed perspective view of the distal portion of an embodiment of an elongated tubular body 76 of a steerable instrument which has two steerable distal bendable zones 74, 75 which are operated by two bendable proximal zones 72, 73, respectively. Figure 5 shows that the elongated tubular body 76 comprises a number of co-axially arranged layers or cylindrical elements including an outer cylindrical element 104 that ends after a first distal flexible zone 74 at the distal end portion 13. The distal end portion 13 of the outer cylindrical element 104 is fixedly attached to a cylindrical element 103 located inside of and adjacent to the outer cylindrical element 104, e.g. by means of spot welding at welding spots 100. However, any other suitable attachment method can be used, including any mechanical snap fit connection or gluing by a suitable glue.

[0054] Figure 6 provides a more detailed view of the distal end part 13 and shows that, in this embodiment, it includes three co-axially arranged layers or cylindrical elements, i.e., an inner cylindrical element 101, a first intermediate cylindrical element 102 and a second intermediate cylindrical element 103. The distal ends of inner cylindrical element 101, first intermediate cylindrical element 102 and second intermediate cylindrical element 103 are all three fixedly attached to one another. This may be done by means of spot welding at welding spots 100. However, any other suitable attachment method can be used, including any mechanical snap fit connection or gluing by a suitable glue. The points of attachment may be at the end edges of inner cylindrical element 101, first intermediate cylindrical element 102 and second intermediate cylindrical element 103, as shown in the figures. However, these points of attachment may also be located some distance away from these edges, be it, preferably, between the end edges and the locations of the flexible zone 75.

[0055] It will be clear to the skilled person that the elongated tubular body 76 as shown in figure 5 comprises four cylindrical elements in total. The elongated tubular body 76 according to the embodiment shown in figure 5 comprises two intermediate cylindrical elements 102 and 103 in which the steering members of the steering arrangement are arranged. However, extra or less cylindrical elements may be provided if desired.

[0056] The steering arrangement in the exemplary embodiment of the elongated tubular body 76 as shown in figure 5 comprises the two flexible zones 72, 73 at the proximal end part 11 of the elongated tubular body 76, the two flexible zones 74, 75 at the distal end part 13 of the elongated tubular body 76 and the steering members that are arranged between related flexible zones at the proximal 11 and distal 13 end parts. An exemplary actual arrangement of the steering members is shown in figure 7, which provides a schematic longitudinal cross-sectional view of the exemplary embodiment of the elongated tubular body 76 as shown in figure 5.

[0057] Flexible zones 72, 73, 74, and 75 are, in this embodiment, implemented by providing the respective cylindrical elements with slits 72a, 73a, 74a, and 75a, respectively. Such slits 72a, 73a, 74a, and 75a may be arranged in any suitable pattern such that the flexible zones 72, 73, 74, and 75 have a desired flexibility in the longitudinal and tangential direction in accordance with a desired design.

[0058] Figure 7 shows a longitudinal cross section of the four layers or cylindrical elements mentioned above, i.e. the inner cylindrical element 101, the first intermediate cylindrical element 102, the second intermediate cylindrical element 103, and the outer cylindrical element 104.

[0059] The inner cylindrical element 101, as seen along its length from the distal end to the proximal end of the instrument, comprises a rigid ring 111, which is arranged at the distal end part 13 of the steerable instrument 10, a first flexible portion 112, a first intermediate rigid portion 113, a second flexible portion 114, a second intermediate rigid portion 115, a third flexible portion 116, a third intermediate rigid portion 117, a fourth flexible portion 118, and a rigid end portion 119, which is arranged at the proximal end portion 11 of the steerable instrument.

[0060] The first intermediate cylindrical element 102, as seen along its length from the distal end to the proximal end of the instrument, comprises a rigid ring 121, a first flexible portion 122, a first intermediate rigid portion 123, a second flexible portion 124, a second intermediate rigid portion 125, a third flexible portion 126, a third intermediate rigid portion 127, a fourth flexible portion 128, and a rigid end portion 129. The portions 122, 123, 124, 125, 126, 127 and 128 together form a steering wire 120 that can be moved in the longitudinal direction like a wire. The longitudinal dimensions of the rigid ring 121, the first flexible portion 122, the first intermediate rigid portion 123, the second flexible portion 124, the second intermediate rigid portion 125, the third flexible portion 128, the third intermediate rigid portion 127, the fourth flexible portion 128, and the rigid end portion 129 of the first intermediate element 102, respectively, are aligned with, and preferably approximately equal to the longitudinal dimensions of the rigid ring 111, the first flexible portion 112, the first intermediate rigid portion 113, the second flexible portion 114, the second intermediate rigid portion 115, the third flexible portion 118, the third intermediate rigid portion 117, the fourth flexible portion 118, and the rigid end portion 119 of the inner cylindrical element 101, respectively, and are coinciding with these portions as well. In this description “approximately equal” means that respective same dimensions are equal within a margin of less than 10%, preferably less than 5%.

[0061] Similarly, the first intermediate cylindrical element 102 comprises one or more other steering wires of which one is shown with reference number 120a.

[0062] The second intermediate cylindrical element 103, as seen along its length from the distal end to the proximal end of the instrument, comprises a first rigid ring 131, a first flexible portion 132, a second rigid ring 133, a second flexible portion 134, a first intermediate rigid portion 135, a first intermediate flexible portion 136, a second intermediate rigid portion 137, a second intermediate flexible portion 138, and a rigid end portion 139. The portions 133, 134, 135 and 136 together form a steering wire 130 that can be moved in the longitudinal direction like a wire. The longitudinal dimensions of the first rigid ring 131, the first flexible portion 132 together with the second rigid ring 133 and the second flexible portion 134, the first intermediate rigid portion 135, the first intermediate flexible portion 136, the second intermediate rigid portion 137, the second intermediate flexible portion 138, and the rigid end portion 139 of the second intermediate cylinder 103, respectively, are aligned with, and preferably approximately equal to the longitudinal dimensions of the rigid ring 111, the first flexible portion 112, the first intermediate rigid portion 113, the second flexible portion 114, the second intermediate rigid portion 115, the third flexible portion 118, the third intermediate rigid portion 117, the fourth flexible portion 118, and the rigid end portion 119 of the first intermediate element 102, respectively, and are coinciding with these portions as well.

[0063] Similarly, the second intermediate cylindrical element 103 comprises one or more other steering wires of which one is shown with reference number 130a.

[0064] The outer cylindrical element 104, as seen along its length from the distal end to the proximal end of the instrument, comprises a first rigid ring 141, a first flexible portion 142, a first intermediate rigid portion 143, a second flexible portion 144, and a second rigid ring 145. The longitudinal dimensions of the first flexible portion 142, the first intermediate rigid portion 143 and the second flexible portion 144 of the outer cylindrical element 104, respectively, are aligned with, and preferably approximately equal to the longitudinal dimension of the second flexible portion 134, the first intermediate rigid portion 135 and the first intermediate flexible portion 136 of the second intermediate element 103, respectively, and are coinciding with these portions as well. The rigid ring 141 has approximately the same length as the rigid ring 133 and is fixedly attached thereto, e.g. by spot welding or gluing. Preferably, the rigid ring 145 overlaps with the second intermediate rigid portion 137 only over a length that is required to make an adequate fixed attachment between the rigid ring 145 and the second intermediate rigid portion 137, respectively, e.g. by spot welding or gluing. The rigid rings 111, 121 and 131 are attached to each other, e.g., by spot welding or gluing. This may be done at the end edges thereof but also at a distance of these end edges.

[0065] In an embodiment, the same may apply to the rigid end portions 119, 129 and 139, which can be attached to one another as well in a comparable manner. However, the construction may be such that the diameter of the cylindrical elements at the proximal portion is larger, or smaller, with respect to the diameter at the distal portion. In such embodiment the construction at the proximal portion differs from the one shown in figure 7. As a result of the increase or decrease in diameter an amplification or attenuation is achieved, i.e., the bending angle of a flexible zone at the distal portion will be larger or smaller than the bending angle of a corresponding flexible portion at the proximal portion.

[0066] The inner and outer diameters of the cylindrical elements 101, 102, 103, and 104 are chosen in such a way at a same location along the elongated tubular body 76 that the outer diameter of inner cylindrical element 101 is slightly less than the inner diameter of the first intermediate cylindrical element 102, the outer diameter of the first intermediate cylindrical element 102 is slightly less than the inner diameter of the second intermediate cylindrical element 103 and the outer diameter of the second intermediate cylindrical element 103 is slightly less than the inner diameter of the outer cylindrical element 104, in such a way that a sliding movement of the adjacent cylindrical elements with respect to each other is possible. The dimensioning should be such that a sliding fit is provided between adjacent elements. A clearance between adjacent elements may generally be in the order of 0.02 to 0.1 mm, but depends on the specific application and material used. The clearance may be smaller than a wall thickness of the steering wires to prevent an overlapping configuration thereof. Restricting the clearance to about 30% to 40% of the wall thickness of the steering wires is generally sufficient.

[0067] As can be seen in figure 7, flexible zone 72 of the proximal end part 11 is connected to the flexible zone 74 of the distal end part 13 by portions 134, 135 and 136, of the second intermediate cylindrical element 103, which form a first set of steering wires of the steering arrangement of the steerable instrument. Furthermore, flexible zone 73 of the proximal end part 11 is connected to the flexible zone 75 of the distal end part 13 by portions 122, 123, 124, 125, 126, 127, and 128 of the first intermediate cylindrical element 102, which form a second set of steering wires of the steering arrangement. The use of the construction as described above allows the steerable instrument 10 to be used for double bending. The working principle of this construction will be explained with respect to the examples shown in figures 8 and 9.

[0068] For the sake of convenience, as shown in figures 7, 8 and 9, the different portions of the cylindrical elements 101, 102, 103, and 104 have been grouped into zones 151 - 160 that are defined as follows. Zone 151 comprises the rigid rings 111, 121, and 131. Zone 152 comprises the portions 112, 122, and 132. Zone 153 comprises the rigid rings 133 and 141 and the portions 113 and 123. Zone 154 comprises the portions 114, 124, 134 and 142. Zone 155 comprises the portions 115, 125, 135 and 143. Zone 156 comprises the portions 116, 126, 136 and 144. Zone 157 comprises the rigid ring 145 and the parts of the portions 117, 127, and 137 coinciding therewith. Zone 158 comprises the parts of the portions 117, 127, and 137 outside zone 157. Zone 159 comprises the portions 118, 128 and 138. Finally, zone 160 comprises the rigid end portions 119, 129 and 139.

[0069] In order to deflect at least a part of the distal end part 13 of the steerable instrument, it is possible to apply a bending force, in any radial direction, to zone 158. According to the examples shown in figures 8 and 9, zone 158 is bent downwards with respect to zone 155. Consequently, zone 156 is bent downwards. Because of the first set of steering wires comprising portions 134, 135, and 136 of the second intermediate cylindrical element 103 that are arranged between the second intermediate rigid portion 137 and the second rigid ring 133, the downward bending of zone 156 is transferred by a longitudinal displacement of the first set of steering wires into an upward bending of zone 154 with respect to zone 155. This is shown in both figures 8 and 9.

[0070] It is to be noted that the exemplary downward bending of zone 156, only results in the upward bending of zone 154 at the distal end of the instrument as shown in figure 8. Bending of zone 152 as a result of the bending of zone 156 is prevented by zone 153 that is arranged between zones 152 and 154. When subsequently a bending force, in any radial direction, is applied to the zone 160, zone 159 is also bent. As shown in figure 9, zone 160 is bent in an upward direction with respect to its position shown in figure 8. Consequently, zone 159 is bent in an upward direction. Because of the second set of steering wires comprising portions 122, 123,

124, 125, 126, 127 and 128 of the first intermediate cylindrical element 102 that are arranged between the rigid ring 121 and the rigid end portion 129, the upward bending of zone 159 is transferred by a longitudinal displacement of the second set of steering wires into a downward bending of zone 152 with respect to its position shown in figure 8.

[0071] Figure 9 further shows that the initial bending of the instrument in zone 154 as shown in figure 8 will be maintained because this bending is only governed by the bending of zone 156, whereas the bending of zone 152 is only governed by the bending of zone 159 as described above. Due to the fact that zones 152 and 154 are bendable independently with respect to each other, it is possible to give the distal end part 13 of the steerable instrument a position and longitudinal axis direction that are independent from each other. In particular the distal end part 13 can assume an advantageous S-like shape. The skilled person will appreciate that the capability to independently bend zones 152 and 154 with respect to each other, significantly enhances the maneuverability of the distal end part 13 and therefore of the steerable instrument as a whole.

[0072] Obviously, it is possible to vary the lengths of the flexible portions shown in figures 7 to 9 as to accommodate specific requirements with regard to bending radii and total lengths of the distal end part 13 and the proximal end part 11 of the steerable instrument orto accommodate amplification or attenuation ratios between bending of at least a part of the proximal end part 11 and at least a part of the distal end part 13.

[0073] In the shown embodiment, the steering wires comprise one or more sets of steering wires that form integral parts of the one or more intermediate cylindrical elements 102, 103. Preferably, the steering wires comprise remaining parts of the wall of an intermediate cylindrical element 102, 103 after the wall of the intermediate cylindrical element 102, 103 has been provided with longitudinal slits that define the remaining steering wires.

[0074] Figure 10 shows a 3D view of an example of a steerable instrument. Like reference numbers refer to the same elements as in other figures. Their explanation is not repeated here. The instruments comprises five coaxial cylindrical elements 202-210. An inner cylindrical element 210 is surrounded by intermediate cylindrical element 208 which is surrounded by intermediate cylindrical element 206 which is surrounded by intermediate cylindrical element 204 which is, finally surrounded by outer cylindrical element 202. Inner intermediate cylindrical element may be made of a flexible spiraling spring. The proximal and distal ends, respectively, of the instrument are indicated with reference numbers 226 and 227, respectively.

[0075] As shown, here, instrument 76 comprises a flexible zone 77 in its intermediate part between flexible zone 72 and flexible zone 74. l.e., intermediate cylindrical element 204 (which is located at the outer side in the area of flexible zone 77) is provided with a slotted structure to provide intermediate cylindrical element with a desired flexibility. The longitudinal length of the slotted structure in flexible zone 77 depends on the desired application. It may be as long as the entire part between flexible zones 72 and 74. All other cylindrical elements 206, 208, 210 inside intermediate cylindrical element 204 are also flexible in flexible zone 77. Those cylindrical elements that have steering wires in the flexible zone 77 are flexible by way of definition. Others are provided with suitable hinges, preferably made by suitable slotted structures.

[0076] Some locations to be operated in a body need specifically designed instruments. E.g., by making the intermediate part 12 of the instrument completely flexible, the instrument can also be used in areas in the body which are only accessible via curved natural access guides/channels, like the colon, the stomach via the oesophagus or the heart via curved blood vessels.

[0077] The instrument can e.g. be designed to be used as a colonoscope. Figure 11 shows a schematic view of a colonoscope 42 in use. The colonoscope 42 is inserted into a colon 30 of a human body. Typically, the colon 30 has several almost square angled sections 32, 34, 36, and 38. If a surgeon needs to operate an area of the colon 30 upstream from square angled section 32 the colonoscope 42 needs to be inserted into the colon 30 along a distance of up to

1.5 meter. Moreover, the colonoscope 42 needs to be so flexible that it can be guided from an anus through all squared angled sections 32-38 of the colon 30 easily without risks of damaging the inner wall of the colon 30.

[0078] In operation, usually, several invasive instruments are inserted through the colonoscope 42 to provide one or more tools for some function at its distal end 44. In colonoscopy, such a tool typically includes a camera lens and a lighting element. To assist the surgeon in steering the camera view to the desired location and view in colon 30, typically, the distal end is deflectable from a longitudinal axis in all angular directions. This also holds for the inserted instruments with tools 2. That can be implemented by providing such an instruments with one or more deflectable zones, like the deflectable zones 16, 17 of the instrument shown in Figures 5-10. These distal deflectable zones are controlled by suitable steering cables accommodated in the instruments connected to a suitable steering mechanism at the proximal ends of the instruments.

[0079] Figure 12 shows a schematic view of a gastroscope 56 in use. The gastroscope 56 is inserted into a stomach 50 of a human body via mouth, oral cavity / throat 54 and oesophagus

52. Especially when a surgeon needs to operate a lower portion of the stomach 50, the gastronoscope 56 needs to be guided through several curved/angled sections. Therefore, the gastroscope 56 needs to be flexible such that there is little risk of damaging inner walls of the mouth/throat 54, oesophagus 52 and stomach 50.

[0080] In operation, usually, several invasive instruments are inserted through the gastroscope 56 to provide one or more tools for some function at its distal end 59. In gastroscopy, such a tool typically includes a camera lens and a lighting element. To assist the surgeon in steering the camera view to the desired location and direction in stomach 50, typically, the distal end 59 of the gastrocope 56 is deflectable from a longitudinal axis in all angular directions. This also holds for the inserted instruments with tools 2. That can be implemented by providing such an instrument with one or more deflectable zones, like the deflectable zones 16, 17 of the instrument shown in Figures 5-10. These distal deflectable zones are controlled by suitable steering cables accommodated in the instruments connected to a suitable steering mechanism of these instruments.

[0081] Instruments according to the invention can be used in such colonoscopes and gastroscopes but also in other applications like instruments designed for entering the lung bronchi. Requirements to such an instrument may be that they show a high rotational stiffness, high longitudinal stiffness, bending flexibility along its entire length and accurate and repeatable deflectability of a steerable tip even in cases of long instruments, e.g., longer than 1 m, and with a relatively small diameter that fits to the working channels within or attached to colonoscopes and gastroscopes.

[0082] In order to better understand the issues dealt with in the present document, first a detailed description is provided of a prior art flexible steerable instrument with Bowden cables with reference to figures 13-15.

[0083] A Bowden cable as known from the prior art can be defined as a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of an inner lining, a longitudinally incompressible layer such as a helical winding or a sheath of steel wire, and a protective outer covering. The cable housing is often called a coil pipe. Here, the term steering wire guiding will be used for the outer cable housing.

[0084] Figure 13 shows an instrument according to prior art with a steerable tip and a flexible body, with Bowden cable arrangements in a length compensation section at one end of the Bowden cable. Each Bowden cable arrangement comprises a steering wire and a surrounding steering wire guiding. The steering wire guiding is attached to the instrument body in the distal end before the proximal end of the steerable tip and is also attached to the instrument body in the proximal end. The length compensation section is positioned between the distal end of the guiding and the proximal end of the guiding, preferably in the proximal end of the instrument. In this drawing the length compensation section has a simple geometry of a curve that can be shortened or elongated. But prior art provides many different solutions for a length compensation section.

[0085] More in detail figure 13 shows a flexible steerable instrument 1300 with a tip section 1301, a flexible body section 1303, a length compensation section 1305, and a steering section 1307 which may comprise a handle. The length compensation section 1305 may be arranged at another longitudinal location, e.g., somewhere inside the body section 1303.

[0086] Steering wires 1309(1), 1309(2) run from the steering section 1307 to the tip section 1301 in order to allow bending the tip section 1301 relative to body section 1303. Inside body section 1303 and length compensation section 1305, steering wires 1309(1), and 1309(2), respectively, are arranged inside a steering wire guidings 1311(1) and 1311(2), respectively. Steering wire guidings 1311(1) and 1311(2), respectively, are held at a fixed position 1317(1) and 1317(2), respectively, at the transition between tip section 1301 and body section 1303. Similarly, steering wire guidings 1311(1) and 1311(2), respectively, are held at a fixed position

1319(1) and 1319(2), respectively, at the transition between length compensation section 1305 and steering section 1307.

[0087] Figure 14 shows the same instrument as figure 13, but now body section 1303 is bent. Tip section 1301 is not bent. The portions of steering wires 1309(1) and 1309(2) inside tip section 1301 have a length L1. The inside curve of the curved part, i.e., the part of hinge 1313, of the body section 1303 has a length L3, and the outside curve has a length L4. The initial length of steering wire guidings 1311(1), 1311(2) inside body section 1303, i.e. figure 13, is L5. The total length of steering wires 1309(1), 1309(2) inside length compensation section 1305 inside the steering section 1307 is L2.

[0088] Due to the bending, L3 is shorter than the initial steering wire guiding length L5 and L4 is longer than the initial steering wire guiding length L5. If one wants that L1 and L2 after the bending are equal to L1 and L2 before the bending, in other words, if one does not want that the tip or the steering device in steering section 1307 deflects due to bending of the body, the length difference between L5 and L3 or L4 has to be absorbed by the length compensation section 1305 as is shown in the drawing. In this drawing, the length compensation section 1305 absorbs the length differences by increasing the curve height of steering wire guiding 1311(1) with the associated portion of steering wire 1309(1) inside (which can absorb a longer length of steering wire guiding 13111) with steering wire 1309(1) outside body section 1303) and decreasing the curve height of steering wire guiding 1311(2) with the associated portion of steering wire 1309(2) inside (which can absorb a shorter length of steering wire guiding 1311(2) with steering wire 1309(2) outside body section 1303). In this way, tip defection is fully isolated from body deflection.

[0089] Figure 15 shows the same instrument as in figures 13 and 14, but now the steering device is deflected for steering the instrument tip section 1301. When the tip section 1301 is deflected as shown, a pull force is generated in steering wire 1309(2) and a push force is generated in steering wire 1309(1). This results in compression or stretching forces in the corresponding body section 1303 and tip section 1301 areas. The steering wire guidings 1311(1) and 1311(2) are flexible enough to allow body section bending but are very stiff in their own longitudinal direction so that they can withstand the compression or stretching forces without significant deformation. The length compensation section 1305 itself has a longitudinal stiffness designed such that it can withstand the compression or elongation forces due to pulling or pushing the steering wires 1309(1), 1309(2) without significant deformation. So, in this configuration the compression and elongation forces are fully absorbed by the Bowden cable arrangement inside length compensation section 1305. Therefor the body section 1303 will not compress or elongate anymore and therefor will not bend. In this way, body section steering as an unwanted result of tip steering is prevented.

[0090] Figures 18-31c are embodiments of the invention. Figures 16-30 relate to flexible invasive steerable instruments in which steering wires are implemented by steering wires 16(i) (i =1, 2, ...., I) made from portions of one or more tubes, e.g., by means of (laser) cutting a suitable slot pattern in such one or more tubes, as explained in detail with reference to figures 1-10. As will be explained in detail, steering wire guidings are implemented by steering wire guiding portions also made from one or more tubes. The embodiments of figures 314-31c can also be implemented with classic steering wires and coil pipes.

[0091] Figure 16 shows a longitudinal cross section through a flexible steerable invasive instrument with a tip section 1613, a flexible body section 1615, a length compensation section 1617, and a steering section 1618 which may comprise a handle, a deflectable steering unit or a robotic steering unit. The length compensation section 1617 may be arranged at another longitudinal location, e.g., somewhere inside the body section 1615 or be integrated inside the steering section 1618. The right hand side is the proximal end and the left hand side is the distal end of the instrument.

[0092] The instrument as shown is made of five tubes coaxially arranged about a central axis 1622. However, other numbers can be applied as well. An inner tube 1601 is arranged inside the instrument, which is flexible at least inside the body section 1615 but stiff in its longitudinal direction. To that end the inner tube 1601 may be provided with suitable hinges 1609 in the body section 1615, made by providing the inner tube 1601 with a suitable pattern of slots. The portions of inner tube 1601 at the transition between tip section 1613 and body section 1615 is indicated with reference sign 1606, and inside length compensation section 1817 with reference sign 1607.

[0093] A first intermediate tube 1619 surrounds inner tube 1601. First intermediate tube 1619 has a steering section portion 1619{1) which may be entirely ring shaped, a plurality of inside 1619(2,i), i.e. one for each steering wire 16(i), in length compensation section 1617, a body section portion 1619(3) which may be ring shaped, and a tip section portion 1619(4) which may be ring shaped and provided with one or more suitable hinges. First intermediate tube 1619 and inner tube 1601 are, preferably, attached to one another at the transition between tip section 1613 and body section 1615 and at the proximal side between the length compensation section 1617 and the steering section 1618, e.g. by laser welding, gluing, etc. Body section portion 1619(3) is flexible at least in the flexible portions of body section 1615.

[0094] A second intermediate tube 1620 (cf. e.g. figure 18a) surrounds first intermediate tube 1619. Second intermediate tube 1620 has steering wires 16(i) running from the proximal end to the distal end of the instrument. These steering wires should be flexible in at least the flexible part of tip section 1613, the flexible part of body portion 1615, and inside length compensation section 1617.

[0095] A third intermediate tube 1621 surrounds second intermediate tube 1620. Third intermediate tube 1621 has a steering section portion 1621(1) which may be entirely ring shaped, a plurality of outside steering wire guiding portions 1621(2,i), i.e. one for each steering wire 16), a length compensation section 1617, a body section portion 1621(3} which may be ring shaped, and a tip section portion 1621(4) which may be ring shaped and provided with one or more suitable hinges. Body section portion 1621(3) is flexible at least in the flexible portions of body section 1615.

[0096] At the distal end of the instrument, i.e., distally beyond the flexing portion of tip section 1613, all steering wires 16(i} are attached to at least one of first and third intermediate tubes 1619 and 1621 to allow for pulling and pushing forces to be transferred to the tip section

1613.

[0097] An outer tube 1602 surrounds third intermediate tube 1621. Outer tube 1602, in the shown example, has — as seen from the proximal end to the distal end - a steering section portion 1604 which may be entirely ring shaped, one or more open portions in length compensation section 1617 in order to allow the length compensation portions of tubes 1619, 1620 and 1621 to increase their extension away from central axis 1622 if desired, a ring shaped portion, a ring shaped portion 1603, a flexible portion 1605 and a ring shaped portion 1606. Ring shaped portion 1606 may be attached to third intermediate tube 1621 at the transition between tip section 1613 and body section 1615.

[0098] Figure 17 shows an enlarged outside view of length compensation section 1617. In this figure, one now also sees an outside steering wire guiding portion 1621(2,3) located on top of a steering wire 16(3) (not visible in this figure). The steering wire guiding portions 1619(2,i), 1621(2,i) are bent radially outward, with the steering element 16(j) in between. The steering element 16(i) is now radially guided by the steering wire guiding portions 1619(2,i), 1621(2,i). Note that Figures 25, 26 show more details of how steering wire guiding portions 1619(2,i), 1621(2,i) may be constructed.

[0099] Figure 18a shows an embodiment were the proximal instrument end is configured for coupling it to for example a robotic steering device or a separate handheld steering device. To that end, each steering wire 16(i) may be provided with an opening 16(i,1) which is arranged in steering section 1618 and radially inside a suitably sized slot in third intermediate tube 1921. Each opening 16(i,1) is configured for receiving an associated mechanical coupling unit of the robotic steering device such that the robotic steering device can individually operate the steering wires 16(i) by means of these mechanical coupling units. Instead of openings 16(i,1) other coupling mechanisms can be used instead.

[00100] Figure 18b shows the same instrument, but now the proximal end of the instrument is configured for steering the distal tip with a bendable section in a similar way as shown in figures 1-10. Of course other steering means like a gimballing handle or other known steering methods can be envisioned.

[00101] The steering wires cross section may have a substantially rectangular shape such that they bend easily in the radial direction, but they are difficult to be bent in the tangential direction. In that case, it is not necessary to also guide the steering wires 18(i) in tangential direction in the length compensation section 1617. Le, they will stay between the inner and outer steering wire guiding portions 1619(2,i) and 1621(2,i} inside the length compensation section 1617 whilst pulled or pushed.

[00102] In case one uses steering elements 16(i) that are also flexible in tangential direction, it might be necessary to also guide the steering wires 16(i) in the tangential direction of the instrument. This can be accomplished as is shown in figures 19 and 20.

[00103] Figure 19 shows lips 1623 on the tangential side of inner steering wire guiding portion 1619(2,i), that can be bent upward towards the outer steering wire guiding portion 1621(2,i) and that can, for instance, be permanently attached to the outer steering wire guiding portion 1621(2,i), by for example brazing, soldering or welding or a snap fit connection.

[00104] Figure 20 shows another embodiment in which the steering wires are prevented from tangential movement by means of islands located in respective openings in the respective steering wires 16(i), which islands are attached to at least one of steering wire guiding portions 1619(2,1) and 1621(2,1). As shown in figure 20, in length compensation section 1617, steering wire 16(1) is provided with a plurality of openings 1627(j)) = 1, 2, 3, ..., J; six are shown) each having an island 1625()) inside. Islands 1625(j) are also cut from tube 1820 and are, when the cutting is finished, still connected to adjacent material of steering wire 16(1) by means of one or more fracture elements 1629(j). Then during assembly these islands 1625(j) can be permanently attached to at least one of steering wire guiding portions 1619(2,1) and 1621(2,1) at an attachment portion 1626(j). This attachment may be done by laser welding, gluing, or bending a lip inside opening 1627(j) such that the distance between steering wire guiding portions 1619(2,1) and 1621(2,1) is larger than the thickness of steering wire 16(1), thus making a radial cage and reducing radial friction. In this way, radial spacers are made, as explained in detail in WO2019009710A1. After attachment, with for example laser welding, the fracture element 1629(j) will fracture upon first activation of steering wire 16(1).

[00105] Fracture elements 1628(j) should be designed in the following way. Before being fractured, each fracture element 1629(j) is attached to opposite portions of island 1627(j) and steering wire 16(i). These opposite portions of island 1627(j) and steering wire 16(i) have a geometrical shape such that the stresses in the fracture element 1628(j) are higher than in the surrounding material and/or structure. Therefore, if a deflection or a high enough force is applied on a structure with a fracture element 1629(j) the stress in the fracture element 1629()) rises above the yield stress of the tube material, causing permanent deflection of fracture element 1629(j). Applying even more deflection or a higher force results in the stress reaching the ultimate tensile stress causing a fracture of fracture element 1629(j). An other mechanism to break the fracture element is achieved by applying low or high cycle fatigue to fracture element 1629(j). The stress in fracture element 1629(j) is raised above the fatigue limit, causing a fatigue fracture. In all cases the stresses in the surrounding structure/material, i.e., island 1627(j) and steering wire 16(i), stays at least below the yield stress of the tube material.

[00106] The examples of figures 19 and 20 can be implemented with respect to any steering wire 16(i).

[00107] In this way, the embodiments of figures 19 and 20 provide for tangential guiding of the steering wires 16(i) and, here, also the inner steering wire guiding portion 1619(2,i) may be attached to the outer steering wire guiding portion 1621(2,i) so that a virtual fully closed steering wire guide is created for each one of them. Of course, also other methods of radially attaching the inner steering wire guiding portions 1619(2,j and outer steering wire guiding portions 1621(2,i), as well as creating a tangential guide can be envisioned. In the remaining sections of the instrument the steering wires 16(i) may be guided radially and tangentially by the surrounding tubes and portions of tube 1620, including suitable spacers, that lay next to the steering element. Radial spacers as explained in WO2019009710A1 can be applied as well.

[00108] Figures 21a and 21b show details of the created steering wire guide in which elastic deformation of the curve shape is made more flexible by cutting slots in steering wire guiding portions 1619(2,i) and 1621(2,i) such that the bending stiffness is less than of a solid strip and such that the length of the outer steering wire guiding portion 1621(2,i) can adapt to the length of the inner steering wire guiding portion 1619(2,i) or visa versa when the curved shape is bent. Figure 21a shows such slots 1633 in inner steering wire guiding portion 1619(2,1) and 1619(2,4), whereas figure 21b shows such slots 1639 in steering wire guiding portion 1621(2,1) and 1621(2,4).

[00109] Figure 21a shows the situation directly after the cutting process is finished and steering wire guiding portion 1619(2,1), 1619(2 4) is still attached to surrounding material of tube 1619 by means of fracture elements 1637. The figure also shows an attachment portion 1635 to which attachment portion 1626(1) of island 1625(1) can be attached. As indicated above, other islands 1625(j) may be attached to inner steering wire guiding portion 1619(2,1) as well.

[00110] Figure 21b shows the situation directly after the cutting process is finished and steering wire guiding portion 1621(2,1), 1621{2,4) is still attached to surrounding material of tube 1621 by means of fracture elements 1641. The figure also shows attachment portions 1643(j) to which attachment portions 1626(j) of islands 1625(j) can be attached.

[00111] The result is a longitudinally more flexible length compensation section 1617 that requires less forces to compress or elongate. This on its turn reflects in an easier bendable body section 1615 of the instrument. Another obtainable result is that when the curve shape in length compensation section 1617 is bent outward or inward, one can balance the longitudinal flexibility of the inner and outer steering wire guiding portions 1619(2,i), 1621(2,i) such, that the average length of the inner and outer steering wire guiding portions 1619(2,i), 1621(2,i) stays exactly equal to the length of the enclosed steering wire 16(i). The bending flexibility should be designed such that the longitudinal flexibility of the length compensation section 1617 still can withstand the tip steering forces without significant elongation or shortening.

[00112] Fig 22 shows a simplified presentation of a multi tube instrument according to the invention. Each set of inner and outer steering wire guiding portions 1619(2,i), 1621(2,i) with associated portion of steering wire 16(i) forms a length compensation element which is pre- shaped in a certain curve.

[00113] Figure 23 shows the same multi tube instrument as figure 22 and how the length compensation element works as was explained before. When the body section 1615 is bent, the curved shape of the length compensation element will deform such that it absorbs the length differences of the inner and outer steering wire guiding portions 1612(2,i), 1621(2,i) and steering wires 18(i) inside body section 1615 as initiated by bending of body segment 1615. Note that, in this way, bending of body section 1615 has no influence on the deflection angles of tip section 1613 and steering section 1618.

[00114] Figures 24a and 24b show an embodiment of an instrument according to the invention in which length change of length compensation section 1615 as viewed in a direction perpendicular to central axis 1622 can be prevented, whilst steering the distal tip of the instrument.

[00115] Figure 24a shows the situation in which body section 1615 is not bent and, thus, the neutral position, whereas figure 24b shows the situation in which body section 1615 is bent and length compensation section 1617 is active.

[00116] In this embodiment, a square frame element 1845 is provided which has a first bar 1645(1) and second bar 1645(2) extending in a first direction and a third bar 1645(3) and fourth bar 1645(4) extending in a second direction perpendicular to the first direction. The right hand side of figures 24a, 24b shows this square frame element 1645 as viewed in the longitudinal direction of the instrument towards the distal end. Reference signs A(i) indicate a set of a steering wire 16(i) with its surrounding steering wire guiding portions 1619(2,i), 1621(2,i). These sets A(i) have a curved shape as shown in the left hand side of figures 24a, 24b. The apex of set A(1), A(2), A(3), A(4), respectively, is slidably connected to bar 1645(4), 1645(3), 1645(1), 1645(2), respectively, with a connection unit 1645(4,1), 1645(3,1), 1645(1,1), 1645(2,1), respectively. Thus, the apex of each set Ai) is restricted in its movement radially but can slide along its associated bar 1645(1), 1645(2), 1645(3), 1645(4) in a direction perpendicular to the radial direction.

[00117] It can be shown that the distance between two opposite sets A(1)/A(3), A(2)/A(4) changes slightly when body section 1615 bends. This slight distance change can be compensated for by using bars 1645(1), 1645(2), 1645(3), 1645(4) that are resilient in the radial direction of instrument 1600.

[00118] ‚An interesting application is holding the square frame element 1645 fixed in place, e.g. the situation of figure 24a or 24b, whilst steering the distal tip by longitudinally moving steering wires 16(i). Then, all sets A(i) are kept in place and will counteract any tendency of the body section 1615 to bend (any further) due to the exerted steering wire forces.

[00119] Another advantage of connecting the apexes of the curved length compensation elements is that it can improve the response of the length compensation elements. When one bends body section 1615, one side of length compensation section 1617 is activated by a pull force in the guiding elements, whereas the opposing side of length compensation section 1617 is activated by a push force in the opposing guide element. If there is difference in the magnitude in the forces, or a difference in movement of Bowden cable elements 1619(2,i), 1621(2,i} due to their length, plays, buckling effects, etc. it is better to directly couple the deformation of Bowden cable elements 1619(2,i), 1621(2,i) at one side of length compensation section 1617 to Bowden cable elements 1619(2,i), 1621(2,i) at the opposing side of length compensation section 1617.

Of course many other mechanisms to couple or freeze the shape or the length of the length compensation section can be envisioned.

[00120] Figures 13 — 24b describe an instrument according to the invention in which a Bowden cable guide is built from portions of a separate first intermediate tube 1619 and a separate second intermediate tube 1621 and in which the steering wires 16(i) are made in a separate in between tube 1620. If one adds supportive inner tube 1601 and supportive outer tube 1602 that provides the structures (hinges) for the bendable sections, however, then one needs 5 tubes to build this instrument. A more efficient way is to make the steering wires 16(i) and the guidings therefore in a single tube. Embodiments of such an implementation are now explained.

[00121] Figure 25 shows an embodiment of an instrument according to the invention in which the inner steering wire guiding portion 1619(2,1) and a substantial portion of steering wire 16(1) are made in one tube, i.e, first intermediate tube 1619. Second intermediate tube 1621 is not shown in figure 25 but in figure 26.

[00122] In this embodiment inner, steering wire 16(1) has the following portions as viewed from the proximal end to the distal end: a flexible steering wire portion 16(1,2) in steering section 1618, a steering wire length compensation portion 16(1,3) in length compensation section 1617, a steering wire attachment portion 16(1,4) in the transition between length compensation section 1617 and body section 1615, and steering wire body section portion 16(1,5). steering wire guiding portion 1619(2,1) and steering wire body section portion 16{1,5) are both made in intermediate tube 1619 whereas all other mentioned portions 16(1,2), 16(1,3) and 16(1,4) are made in tube

1620.

[00123] Steering wire attachment portion 16{1,4) is provided with an opening 1648 in which a sliding element 1647 is located. This sliding element 1647 is attached first intermediate tube 1619, e.g. by laser welding, gluing, etc such that steering wire attachment portion 16(1,4) can slide along sliding element 1647 in the longitudinal direction. Moreover, steering wire attachment portion 16(1,4) is attached to steering wire body section portion 16(1,5). This attachment can be made with any suitable attachment method, preferably laser welding. In this way, any push or pull action exerted on flexible steering wire portion 16{1,2) is directly transferred to the same movement of steering wire body section portion 16(1,5) (and further to the tip section 1613).

[00124] The same construction holds for all steering wires 16(i).

[00125] After the product of figure 25 is finished third intermediate tube 1621 containing the outer steering wire guiding portion 1621(2,1) is slid over this product, as shown in figure 26. Outer steering wire guiding portion 1621(2,1) is, at its distal end attached to sliding element 1647 at an attachment point 1655. This can, e.g., be done by laser welding, gluing, etc. Moreover, third intermediate tube 1621 is flexible at the longitudinal location where flexible steering wire portions 16(1,2) are located such as to make a bendable steering section 1618. This is, here, done by a suitable pattern of slots 1653.

[00126] Figure 26 shows the finished assembly in which the complete instrument is made in three tubes 1619, 1620, 1621. First intermediate tube 1619 contains both inner steering wire guiding portions 1619(2,i) and body section steering wire portions 16(i,5). Third intermediate tube 1621 contains outer steering wire guiding portions 1621(2,i) and the further outer body structure.

[00127] One will understand that no extra inner tube 1601 or outer tube 1602 is needed anymore.

[00128] Of course one can envision more embodiments in which body structures, steering wires and Bowden cable elements are combined in tubes with the intention to reduce the number of required tubes and to make assembly of such an instrument as easy as possible.

[00129] Figure 27 shows an embodiment in which the compressible or stretchable curvy shape of length compensation section 1617 can be made in the tangential direction of the instrument without increase of the instrument overall diameter and without the necessity of a separate shaping process. In this embodiment, no separate construction of a steering wire guiding is required. The steering wires 16(i) are guided by an inner and outer tube in the radial direction and by longitudinal guiding elements in the tangential direction, which lye adjacent to the steering wire 16(i). One can also envision that many other shapes are possible as long as the shape is longitudinally compressible or stretchable and as long as friction on the steering wire 16(i) is kept to an acceptable level. This latter observation is also applicable to radially formed shapes as shown in figures 13-26.

[00130] In the implementation example of figure 27, only parts of inner tube 1619 and intermediate tube 1620 are shown. Outer tube 1621 is not shown. Each steering wire 16) is located between two adjacent longitudinal guiding elements 1620(2,1), 1620(2,2), 1620(2,3) which are also formed from tube 1620, e.g., by laser cutting. These guide elements can be coupled by a bridging element in the inner tube 1601 or outer tube 1602 to create a more defined channel. Each steering wire 16(i) has a steering wire steering section portion 16(i,2), a steering wire length compensation section portion 16(i,3) and a steering wire body section portion 16(i,4) (their tip portions are not shown but may be equal to the other embodiments). At the transition between length compensation section 1617 and steering section 1618, each steering wire steering section portion 16(i,2) is tangentially located between two adjacent proximal longitudinal guiding element portions 1620(2,1) which are attached to inner tube 1619 or outer tube 1621 or both by, e.g., laser welding, gluing, etc. at location 1657.

[00131] In the length compensation section 1617, each steering wire length compensation section portion 16,3) is tangentially located between two adjacent longitudinal guiding element length compensation portions 1620(2,2). In the body section 1615, each steering wire body section portion 16(i,4) is tangentially located between two adjacent longitudinal guiding element body portions 1620(2,2) which run to the transition between the body section 1615 and tip section 1613 and are attached there the inner tube 1619 or outer tube 1621 or both by, e.g., laser welding, gluing, etc. to prevent longitudinal motion at that location.

[00132] Figures 28a and 28b show an embodiment of a length compensation section 1617 that can be built in one tube 1620 and that does not require forming in a radial way. In fact, this length compensation section 1617 can be fully enclosed by a single inner and a single outer tube

1619, 1621 as in the embodiment of figure 27. Figure 28a shows a flat representation and figure 28b shows the ‘as cut’ 3D presentation. These figures show an embodiment with two steering wires 16(1), 16(2) located at 180 degrees rotated relative to one another. However, if the diameter of the tubes is large enough, more than two steering wires may be applied. Also, an embodiment with only one steering wire can be made.

[00133] Each one of the steering wires 16(i) is split into two portions, i.e., a first portion and a second portion. The first portion is provided with a protrusion 16(i,9) extending in the tangential direction at a predetermined angle <90 degrees but > 0 degrees. For instance, 30 degrees < angle < 80 degrees. The second portion, which is attached to the distal end of the tip section 1613, has a recess 16(i,8), e.g., located between two extensions 16(i,6) and 16(i,7). The recess 16(i,8) is shaped to receive protrusion 16(i,9) in a slidable way. To that end, in an embodiment, recess 16(i,8) has an identical form as protrusion 16(i,9), i.e., is also extending in the tangential direction at the same angle.

[00134] In between the steering wires 16(i), steering wire guiding elements are provided. These steering wire guiding elements are attached to the body of the instrument. In the shown embodiment, they are located 90 degrees rotated from the steering wires 164i) in the tangential direction. These steering wire guiding elements are grouped in sets of two steering wire guiding elements. Each set has a first steering wire guiding element 1620(3,1), 1620(3,3) and a second steering wire guiding element 1620(3,2) and 1620(3,4). Each first steering wire guiding element 1620(3,1), 1620(3,3) has a recess 1620(3,1,1), 1620(3,3,1). Each second steering wire guiding element 1620(3,2), 1620(3,4) has a protrusion 1620(3,2,1), 1620(3,4,1) which is received in the recess 1620(3,1,1), 1620(3,3,1) of first steering wire guiding element 1620(3,1), 1620(3,3). Both protrusion 1620(3,2,1), 1620(3,4,1) and recess 1620(3,1,1), 1620(3,3,1) are extending in the tangential direction at a predetermined angle <90 degrees but > 0 degrees. For instance, 30 degrees < angle < 80 degrees. These angles may be the same as applied in the steering wire protrusions 16(i,9) and steering wire recesses 16(i,8).

[00135] First steering wire guiding elements 1620(3,1) and 1620(3,3) are connected to the body of the instrument in the area of the proximal end of the steerable tip section. Second steering wire guiding elements 1620(3,2) and 1620(3,4) are connected to suitable portions of the body of the instrument too.

[00136] When the body section 1615 of the instrument of figures 28a, 28b is bent, the proximal end of first steering wire guiding elements 1620(3,1) and 1620(3,3) will longitudinally displace over a certain length. Because of this displacement, the tilted protrusion 1620(3,2,1), 1620(3,4,1) will tangentially slide in or out the tilted recess 1620(3,1,1), 1620(3,3,1). Thus, second steering wire guiding element 1620(3,2), 1620(3,4) will move tangentially. In this movement it will also tangentially displace a first portion of steering wire 16() that is attached longitudinally to the steering device at the proximal end of the instrument. When the first portion of steering wire 16(i) that is attached to the steering device is displaced tangentially, it will longitudinally displace the second portion of steering wire 16(i). By properly selecting the tangential tilt angles of the protrusions and recesses of all elements, the length of change of steering wire 16(i) may be compensated such that the tip section 1613 does not deflect due to bending of the body section 1615. The construction now works as a length compensation element.

[00137] Yet, if one moves the steering wires in a longitudinal direction such as to deflect the tip section 1613 in a desired way this is not affected by the shown construction. Longitudinal movement of the first portion of steering wire 16(i) is transferred to a same longitudinal movement of the second portion of steering wire 16().

[00138] Figures 28a, 28b describe an embodiment of a sliding mechanism that copies a longitudinal displacement of a passive steering wire end in exactly the same amount and direction to a steering wire end. Of course other sliding or lever mechanisms can be envisioned.

[00139] Figures 27, 28a/28b show only two possible embodiments in which the length compensation section 1617 is cut in a single tube 1620. One can envision that more shapes are possible and that also length compensation sections can be build making use of more than one tube.

[00140] Figure 29 shows an embodiment in which the Bowden cable arrangement, in the length compensation section 1617, is extending in the radially inward direction toward central axis 1622. For the sake of clarity, figure 29 only shows tube 1619 and its length compensation portions 1619(2,i). The other tubes 1620 and 1621 have a similar design in length compensation section 1617. Moreover, inner tube 1601 and outer tube 1602 may be applied as well. In order to provide enough inner space for each set of elements 1619(2,i), 16(i) and 1621(2,i) inside length compensation section 1617, adjacent such sets 1619(2,i), 16(i) and 1621(2,i) in the tangential direction may be, as shown, shifted along a certain longitudinal distance such that they cannot touch one another when bending inside to the central axis 1622.

[00141] Figure 30 shows an embodiment in which has at least one longitudinal guiding element length compensation portion 1620(2,2) is tangentially located adjacent to each steering wire 16(i} in length compensation section 1817. The elements in the length compensation section bend radially outward. The figure shows one such longitudinal guiding element length compensation portion 1620(2,2) for each steering wire 18(i) but there may be one at either side.

Each longitudinal guiding element length compensation portion 1620(2,2) is cut from the same tube 1620 as from which steering wires 16(i} are cut. They are separated from one another by a small slot which may be as small as resulting from the smallest possible laser beam used to make the slot.

[00142] Each longitudinal guiding element length compensation portion 1620(2,2) is a portion of a longitudinal guiding element 1620(2,1), 1620(2,2), 1620(2,3). At the transition between length compensation section 1617 and steering section 1618, each steering wire steering section portion 16(i,2) is tangentially located between two adjacent proximal longitudinal guiding element portions 1620(2,1) which are attached to inner tube 1619 or outer tube 1621 or both by, e.g., laser welding, gluing, etc. In the body section 1615, each steering wire body section portion 16(i,4) is tangentially located between two adjacent longitudinal guiding element body portions 1620(2,3) which run to the transition between the body section 1615 and tip section 1613 and are attached there to the inner tube 1619 or outer tube 1621 or both by, e.g., laser welding, gluing, etc. to prevent longitudinal motion at that location. Again, separation slots may be very small, i.e., as small as resulting from the smallest possible laser beam used to make the slot.

[00143] Figure 30 also shows one or more cover plates 1659, 1661 in length compensation section 1617. l.e., one or more cover plates 1659, e.g., cut from outer tube 1621, cover steering wires 16(i) on their radial outside and are attached to an adjacent longitudinal guiding element length compensation portion 1620(2,2), e.g., by laser welding, gluing, etc. Moreover, one or more cover plates 1661, e.g., cut from inner tube 1619, cover steering wires 16{ on their radial inside and are attached to an adjacent longitudinal guiding element length compensation portion 1620(2,2), e.g., by laser welding, gluing, etc. Thus, in length compensation section 1617 each steering wire 16(i) is guided by adjacent guiding element at at least three sides. Guiding at four sides may be implemented too.

[00144] Figures 31a thru 31c show different embodiments of an electro mechanical length compensation section 1617 which can be applied both in a steerable deflectable instrument with wires in the form of classic cables 1309(i) and steering wires 16(i) manufactured from a tube. In the latter case, the steerable deflectable instrument may be one of the embodiments as explained in the present document with reference to any one of the earlier figures 13-27, 19, 30. Because of that, the tip section is indicated with both reference signs 1301 and 1613, and the body section is indicated with both reference signs 1303 and 1615. If designed for robotic use, length compensation section 1617 can be made an integral part of a robotic steering section which can be coupled to the steering wire guiding and the steering wires 16(i).

[00145] Figure 31a shows an embodiment in which proximal ends of the steering wire guidings are coupled to sensors 1663(i). The sensors 1663(i) are connected to a processor 1670 to send respective sensor signals 1667(i) to processor 1670. These sensors 1663(i) measure magnitude and longitudinal direction of the movement of the proximal end of each steering wire guiding when the body section 1303, 1615 is bent. The respective sensor signals 1667(i) are indications of these movement magnitudes and movement directions. Processor 1670 generates a compensation signal 1669(i) for each one of a plurality of actuators 1665(i) in dependence on the sensor signals 1671(i). Each actuator 1665(i) is coupled to one steering wire 1309(i) / steering wire 16(i} such that each steering wire 1309(i) / steering wire 16(i) is moved in the same direction and along the same path length as the proximal end of the respective steering wire guiding as measured by sensor 1663(i). In this way each set of one sensor 1663(i) and one actuator 1665(i) functions as a length compensation unit for one steering wire 1309(i) / steering wire 16(i) and its associated steering wire guiding.

[00146] Alternatively, a set of separate processors is applied each one connected to one set of one sensor 1663(i) and one actuator 1665(i) to perform the above mentioned function. Each one of the set of separate processors can be either located close to or inside a respective sensor 1663(i) or close to or inside a respective actuator 1665(i).

[00147] Moreover, in this example, each actuator 1665(i) is configured to move its steering wire 1309(i) / steering wire 16(i) as controlled by a suitable actuator signal generated by processor 1870 to control deflection of the tip section 1301/1613. Processor 1670 can generate the compensation signal and actuation signal simultaneously. This can be useful for active steering of the tip section 1301/1613 while advancing the instrument through a curved channel, e.g., inside a human body.

[00148] Each applied processor is equipped with a central processing unit, CPU, connected to suitable memory units (RAM, ROM, EPROM, etc.) and to suitable input / output units. The memory units are storing suitable computer programs which, once loaded by the CPU, provide the CPU with the capacity to perform the required functions. Input units are configured to receive input signals, e.g. from sensors 1663(i) and send them to the CPU for further processing. Output units are configured to receive output signals from the CPU and transmit them to external devices like actuation motors 1665(i) and brakes 1671(i).

[00149] Figure 31b shows the same setup as figure 31a, but now each sensor 1663(i) is equipped with a brake device 1671(i) which is also coupled to processor 1670. Brake device is configured to either allow or block longitudinal movement of the respective steering wire guiding proximal end. Each brake device 1671(i) can be activated by processor 1670 with a suitable brake control signal at the moment that the processor 1670 generates actuation signals for the actuators 1665(i) to control deflecting of tip section 1301/1613 with steering wires 1309() / steering wires 16{Ï) but the body section 1303/1615 is not allowed to change its current bent or unbent status. In this way the steering wire guidings are then kept in a stationary position and, consequently, body section 1303/1615 is kept in its current, possibly curved position. Thus, activation of the steering wires 1309(i) / steering wire 16(i) does not result in steering of the body section 1303/1615.

[00150] Figure 31c shows another embodiment of the system as shown in figure 31b, but now each actuator 1665(i) is mechanically coupled to a proximal end of its associated steering wire guiding and is configured to move with the steering wire guiding proximal end during body section bending and to keep the distance that steering wire 1309(i) / steering wire 16() is extending proximally outside its steering wire guiding constant as long as no control signal is received by the actuator 1665(i). In this embodiment, the mechanical unit containing the actuator 1665(i) can also be equipped with a brake device 1671(i) as in figure 31b, that holds the actuator 1665(i) and, thus, steering wire guiding proximal end in a certain fixed position as long as actuation signals are received. As one can envision, it is also possible to replace the steering wire guiding with simpler elements like a simple wire that activates the sensor.

[00151] The material removal means can be a laser beam that melts and evaporates material or water jet cutting beam and this beam can have a width of 0.01 to 2.00 mm, more typically for this application, between 0.015 and 0.04mm.

[00152] The wall thickness of tubes depend on their application. For medical applications the wall thickness may be in a range of 0.03-2.0 mm, preferably 0.03-1.0 mm, more preferably

0.05-0.5 mm, and most preferably 0.08-0.4 mm. The diameter of tubes depend on their application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably

0.5-10 mm, more preferably 0.5-6 mm. The radial play between adjacent tubes may be in range of 0.01 — 0.3 mm.

[00153] Longitudinal and other elements in one tube can be attached to longitudinal and other elements in adjacent tubes such that they are together operable to transfer a longitudinal motion from a steering wire at the proximal end of the instrument to a bendable portion of the instrument at the distal end of the instrument such that the bendable portion bends. This is explained in detail in WO 2017/213491 (cf. e.g. figures 12, 13a and 13b in that PCT application) of the present applicant.

[00154] It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregeing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The present invention is not limited to the disclosed embodiments but comprises any combination of the disclosed embodiments that can come to an advantage.

[00155] Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the description and claims, the word “comprising” does not exclude other elements, and the indefinite article “a” or “an” does not exclude a plurality. In fact it is to be construed as meaning “at least one”. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention. Features of the above described embodiments and aspects can be combined unless their combining results in evident technical conflicts.

Claims (12)

Conclusions A cylindrical instrument comprising at least a first tube (1601; 1619), a second tube (1620) surrounding the first tube (1601; 1619), and a third tube (1602; 1621) surrounding the second tube ( 1620), the instrument surrounding at least a bendable tip section (1613), a control section (1618), a flexible body section (1615) between the tip section (1613) and the control section (1618), a length compensation section (1617), and one or has more control cables (16(i)) extending from the control section (1618) to the tip section (1613) such that the tip section (1613) can be deflected by the one or more control cables (16(i)} in a longitudinally of the cylindrical instrument, the cylindrical instrument comprising a Bowden cable arrangement for each control cable (16(i)) within the body section (1615) and the length compensation section (1617), each Bowden cable arrangement having at least one control cable (16(i)) which is at least partially surrounded n by control cable guide portions, wherein both each control cable (16(i)} and the control cable guide portions are portions of at least one of the first tube (1619), the second tube (1620), or the third tube (1621). The cylindrical instrument of claim 1, wherein, in the length compensation section (1617), the one or more control cables (16(i)) and the control cable guide portions at least partially surrounding it have a curved configuration extending either radially outward from a center axis (1622), radially inward to the center axis (1622), or tangential to the center axis (1622). The cylindrical instrument according to claim 1 or 2, wherein, in the length compensation section (1617), control cable guide portions associated with one control cable (16(i)), an inner control cable guide portion (1619{2,i)), which includes a portion of the first tube (1619), and an outer control cable guide portion (1621(2,1)) which is a portion of the third tube (1621). The cylindrical instrument of claim 3, wherein, in the length compensation section (1617), control cable guide portions include one or more radially oriented tabs (1623), tangentially adjacent to the control cable (16(i)), and attached to at least one of the inner control cable guide section (1619{(2,i}) or the outer control cable guide section (1621{(2,i}) are attached. The cylindrical instrument of claim 3, wherein, in the length compensation section (1617), control cable guide portions comprise one or more islands (1625/(j)) arranged slidably in at least one control cable (16(i)) to provide tangential limit movement of the at least one control cable (16(i)). A cylindrical instrument according to any one of the preceding claims, wherein a square member (1645) is provided, which has a first rod (1645(1)) and a second rod (1645(2)), both extending in a first direction extending, and a third rod (1645(3)) and a fourth rod (1645(4)), both extending in a second direction, perpendicular to the first direction, with the first and second rods (1645(1) , 1645(2)) are slidably connected to tips of opposing sets of one control cable and associated control cable guide sections in the length compensation section (1617), the third and fourth rods (1645(3), 1645(4)) being slidably connected to tips of other opposing sets of a control cable and associated control cable guide sections in the length compensation section (1617). A cylindrical instrument according to any one of the preceding claims, wherein portions of one control cable (16(i)) are in different of the first, second and third tubes (1619, 1620, 1621) in at least two different sections of the at least one bendable end section (1613), the control section (1618), the flexible body section (1615) and the length compensation section (1617) are located. A cylindrical instrument comprising at least a bendable tip section (1301; 1613), a steering section (1618), a flexible body section (1615) between the tip section (1613) and the steering section (1618), a length compensating section (1617), and one or more more control cables (16(i)), 1309(i)), extending from the control section (1618) to the tip section (1613) such that the tip section (1613) can be deflected by the one or more control cables (16( i), 1309(i)) in a longitudinal direction of the longitudinal instrument, the cylindrical instrument incorporating a Bowden cable arrangement for each control cable (16(i), 1309(i)) within the body section (1615) and the length compensation section (1617) each bowden cable assembly comprising at least a control cable (16(i), 1309(i)) and a control cable guide, each control cable guide having a distal control cable guide end attached to the cylindrical instrument at the transition between the end sec tie(1301; 1613) and the body section (1303; 1615), and a proximal control cable guide end extending within the length compensation section (1617), the cylindrical instrument having one or more sensors (1663(i)), each sensor (1663(i) ) is configured to sense longitudinal movement of one of the proximal control cable guide ends, one or more actuators (1665(i)), each actuator (1665(i)) configured to sense longitudinal movement of one control cable (16(i), 1309(i)), so as to compensate for longitudinal movement of an associated proximal control cable guide end due to flexion of the body section (1303; 1615). The cylindrical element of claim 8, wherein each sensor (1663(i)) is configured to send a sensor signal to a processor, the processor being configured to send an activation signal for each actuator (1665(i)) in dependence on an associated generate sensor signal such that each actuator (1665(i)) performs compensated longitudinal movement of its associated control cable (16(i), 1309(i}). The cylindrical member of claim 8, wherein each sensor is configured as a mechanical linkage such that each actuator (1665(i)) is mechanically coupled to an associated control cable guide proximal end, and is configured to move with the control cable guide proximal end during bending of the body section and at a distance that the control cable (16(i), 1309(1})) extending proximally beyond an associated control cable conduit constant, as long as no actuation signal is received by the actuator (1665(i)). A cylindrical instrument according to any one of claims 8 to 10, comprising a braking device (1671(i)) for each proximal end of the control cable guide, each braking device (1671(i)) configured to prevent either longitudinal movement of the respective control cable guide proximal end allow or block. A cylindrical instrument comprising at least a first tube (1601; 1619), a second tube (1620) surrounding the first tube (1601; 1619), and a third tube (1602; 1621) surrounding the second tube ( 1620), the instrument surrounding at least a bendable tip section (1613), a control section (1618), a flexible body section (1615) between the tip section (1613) and the control section (1618), a length compensation section (1617), and one or has more control cables (16(i)) extending from the control section (1618) to the tip section (1613) such that the tip section (1613) can be deflected by the one or more control cables (16(i)) in a longitudinally of the cylindrical instrument, each control cable (16(i)) comprising portions of at least one of the first tube (1619), the second tube (1620) or the third tube (1621), wherein, in the length compensation section (1617), each control cable (16(i)) includes a first portion and a second portion, the first e portion includes a protrusion (16(i,9)), and the second portion includes a protrusion-receiving recess (16(i,8), wherein both the protrusion (16(i,9}) and the recess (16( i,8) be angled with respect to a tangential direction of the cylindrical instrument, and configured to accommodate length changes of the one or more control cables {16{i}} in the body section (1615) due to flexion of the body section (1615). compensate.