Patent Publication Number: US-2021178610-A1

Title: Flexible mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a flexible mechanism, and more particularly, to a flexible mechanism that minimizes unintended control due to a deflection of an arrange route of the flexible mechanism. 
     2. Description of the Prior Art 
     The flexible mechanism may be utilized for a medical purpose for observing or treating a narrow space having curves or for a robot for controlling an end effector of a robot. 
       FIGS. 1A and 1B  will be referenced to describe a flexible mechanism according to the related art in more detail. 
     Referring to  FIG. 1A , the flexible mechanism  10  according to the related art may include a backbone  11 , a plurality of steering wires  12  (W 1 , W 2 , and W 3 ), a handler  14  functioning as a steering handling device, and an end effector  15 . The backbone  11  is introduced into a predetermined route and is deflected according to the route. The steering wires  12  are disposed along the backbone  11 , and a handling force provided by the handler  14  is transferred to the end effector  15 . 
     In this way, when the handling force is transferred from the handler  14  to the end effect  15  through the steering wire  12 , an unintended handling force may be caused according to the posture of the backbone, that is, the deflection of the route, along which the backbone passes. 
     For a more detailed description, referring to  FIG. 1A , when the flexible backbone  11  has a linear form, a distance between a first cross-section ES 1  and a second cross-section ES 2  of the flexible backbone  11  may be L. In this case, distances between the first cross-sections ES 1  and the second cross-sections ES 2  of the steering wires W 1 , W 2 , and W 3  provided in the interior of the flexible backbone  11  may be the same as L. In this case, because the lengths of the flexible backbone  11  and the steering wires W 1 , W 2 , and W 3  are the same, it may be understood that the relative displacements are 0. 
     Then, as illustrated in  FIG. 1B , when the flexible mechanism  10  is deflected, a relative displacement between the backbone  11  and the steering wire  12  may be caused. For example, referring to area A illustrated in  FIG. 1B , the first steering wire W 1  protrudes while passing by a first cross-section ES 1  and a second cross-section ES 2 . As another example, Referring to area B illustrated in  FIG. 1B , the third steering wire W 3  fails to reach a site between the first section ES 1  and the second section ES 2 . In this case, because an unintended change may be caused by a tension that influences an end effector  15  by the steering wires  12 , a problem of an unintended control may be caused. 
     SUMMARY OF THE INVENTION 
     A technical purpose of the present disclosure is to provide a flexible mechanism that accurately transfers a handling force of a handler to an end effector. 
     Another technical purpose of the present disclosure is to provide a flexible mechanism that maintains a difference between the length of a backbone and the lengths of the routes of steering wires even when the backbone is deflected. 
     Another technical purpose of the present disclosure is to provide a flexible mechanism that minimizes an influence on the shape of a backbone by steering wires. 
     Another technical purpose of the present disclosure is to provide a flexible mechanism that minimizes a friction between steering wires and a backbone. 
     Another technical purpose of the present disclosure is to provide a flexible mechanism that minimizes an unintended control even when a plurality of backbone branches. 
     The technical objects of the present disclosure are not limited to the above-described ones. 
     In accordance with an aspect of the present disclosure, there is provided a flexible mechanism including: a backbone extending in a lengthwise direction thereof; a first steering wire group including one or more steering wires disposed in a spiral direction of a first direction along the lengthwise direction of the backbone and configured to transfer a handling force applied to ends thereof to an end effector; and a second steering wire group including one or more steering wires disposed in a spiral direction of a second direction, which is different from the first direction, along the lengthwise direction of the backbone and configured to transfer a handling force applied to ends thereof to the end effector. 
     The steering wires in the first steering wire group and the steering wires in the second steering wire group may be disposed such that distances thereof from the center of the backbone in a direction toward a side surface of the back bone are different along the lengthwise direction of the backbone. 
     The steering wires in the first steering wire group and the steering wires in the second steering wire group may have the same cycle, and the steering wires in the first steering wire group and the steering wires in the second steering wire group may be disposed along the lengthwise direction of the backbone while the inner sides and the outer sides thereof alternate. 
     The first steering wire group may include a 1-1-th steering wire and a 1-2-th steering wire, the second steering wire group may include a 2-1_th steering wire and a 2-2-th steering wire, and the 1-1-th steering wires and the 1-2-th steering wires may be disposed on the outer side of the 2-1-th steering wire and the 2-2-th steering wire with respect to a radial direction of the backbone during a half of a cycle of a spiral, and may be disposed on the inner side of the 2-1-th steering wire and the 2-2-th steering wire with respect to the radial direction of the backbone during the remaining half of the cycle of the spiral. 
     The number of the steering wires in the first steering wire group may be an even number, the number of the steering wires in the second steering wire group also may be an even number, and the number of the steering wires in the first steering wire group and the number of the steering wires in the second steering wire group may be the same. 
     A spiral groove, in which the steering wires in the first steering wire group and the steering wires in the second steering wire group are disposed, may be provided on an outer surface of the backbone, and a hollow, through which the steering wires pass, may be provided in the spiral groove, and a spiral maintaining part configured to maintain spiral structures of the steering wires may be further provided. 
     The friction areas of the spiral maintaining part and the steering wires may be smaller than the lengthwise areas of the spiral maintaining part. 
     The backbone may include: a first backbone, in which the first steering wire group and the second steering wire group are provided, and a second backbone, in which the first steering wire group and the second steering wire group are provided, and the first backbone and the second backbone may be spirally twisted. 
     The flexible mechanism may further include a spiral rail part having a spiral rail to provide spiral routes for the first backbone and the second backbone. 
     The backbone may include a plurality of backbone branches extending in a direction that is normal to the lengthwise directions of the first steering wire group and the second steering wire group, and the plurality of backbone branches may be disposed to be spaced apart from each other along the lengthwise directions of the first steering wire group and the second steering wire group. 
     According to the embodiment of the present disclosure, an unintended tension due to a deflection of the backbone can be minimized by disposing the steering wires between the steering handling device and the end effector in a spiral structure. 
     According to the embodiment of the present disclosure, a phenomenon, in which the shape of the backbone is distorted when the steering wires are handled by providing the steering wires of the steering wire groups such that the steering wires have spiral directions that are opposite to each other. 
     According to the embodiment of the present disclosure, the steering wires of the steering wire groups may be disposed to alternate to the inner side and to the outer side such that unintended forces between the steering wires of the steering wire groups are offset. 
     The effects of the present disclosure are not limited to the above-described ones, and may become clearer by the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features, and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1A and 1B  are views illustrating a flexible mechanism according to the related art; 
         FIGS. 2 to 5B  are views illustrating a flexible mechanism according to an embodiment of the present disclosure; 
         FIGS. 6A and 6B  are views illustrating a flexible mechanism according to a modification of the present disclosure; 
         FIG. 7  is a view illustrating a flexible mechanism according to another modification of the present disclosure; 
         FIG. 8  is a view illustrating a flexible mechanism according to another modification of the present disclosure; 
         FIGS. 9 to 11B  are views illustrating a flexible mechanism according to another modification of the present disclosure; and 
         FIGS. 12 and 13  illustrate an experimental result for showing the excellency of the embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present disclosure is not limited to the embodiments, but may be realized in different forms. The embodiments introduced here are provided to sufficiently deliver the spirit of the present disclosure to those skilled in the art so that the disclosed contents may become thorough and complete. 
     When it is mentioned in the specification that one element is on another element, it means that the first element may be directly formed on the second element or a third element may be interposed between the first element and the second element. Further, in the drawings, the shapes and the sizes of the areas are exaggerated for efficient description of the technical contents. 
     Further, in the various embodiments of the present disclosure, the terms such as first, second, and third are used to describe various elements, but the elements are not limited to the terms. The terms are used only to distinguish one element from another element. Accordingly, an element mentioned as a first element in one embodiment may be mentioned as a second element in another embodiment. The embodiments illustrated here include their complementary embodiments. Further, the term “and/or” in the specification is used to include at least one of the elements enumerated in the specification. 
     In the specification, the terms of a singular form may include plural forms unless otherwise specified. In the specification, the terms “including” and “having” are used to designate that the features, the numbers, the steps, the elements, or combinations thereof described in the specification are present, and may be understood that one or more other features, numbers, step, elements, or combinations thereof may be added. Further, in the specification, “connected to” is used to mean a plurality of elements are indirectly or directly connected to each other. 
     Further, in the following description of the present disclosure, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear. 
       FIGS. 2 to 5B  are views illustrating a flexible mechanism according to an embodiment of the present disclosure. 
     Referring to  FIGS. 2 to 5B , a flexible mechanism  100  according to an embodiment of the present disclosure may include at least one of a backbone  110 , a first steering wire group W 1 , and a second steering wire group W 2 . Hereinafter, the elements will be described in detail. 
     The backbone  110  may perform a function of providing a predetermined route. For example, when the flexible mechanism  100  is used for a medical purpose, the backbone  110  may move along a route (e.g., a large intestine, a throat, or the like) in a human body. Then, the backbone  110  may be formed of a flexible material to be curved along a defection in the human body. It is apparent that the backbone  110  is formed of a human body-friendly material because it moves in the route in the interior of the body. As another example, even when the flexible mechanism  100  is used for a robot, it may be formed of a flexible material. 
     Steering wires W 1  and W 2  that connect an end effector and a steering handling device may be disposed in the backbone  110 . For example, a spiral groove may be provided on an outer peripheral surface of the backbone  110  such that the steering wires W 1  and W 2  are disposed in the spiral groove. For example, a spiral tunnel may be provided in the interior of the backbone  110  such that the steering wires W 1  and W 2  are disposed in the spiral tunnel. The backbone  110  may be manufactured through various techniques such as injection-molding and 3D printing. Hereinafter, it is assumed for convenience of description that a spiral tunnel, in which the steering wires W 1  and W 2  are disposed, is provided in the interior of the backbone  110 . 
     The backbone  110  may have various shapes. For example, as illustrated, the backbone  110  may have a cylindrical shape that extends in a lengthwise direction A-A′ of  FIG. 2 . Another example will be described with reference to  FIG. 7 . 
     The first steering wire group W 1  may include one or more steering wires. According to an example, the first steering wire group W 1  may include an even number of steering wires. In  FIG. 2 , it is assumed for convenience of description that the first steering wire group W 1  includes two steering wires of a 1-1-th steering wire W 1 - 1  and a 1-2-th steering wire W 1 - 2 , but this is a simple example and the technical spirit of the present disclosure is not limited by the assumption. 
     The steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  may adjust a tension according to a handling force applied to a steering handling device connected to ends thereof to transfer a driving force for controlling the end effector connected to the opposite ends thereof. 
     The steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  may be disposed spirally along the lengthwise direction of the backbone  110 . For example, the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  may be disposed in the backbone  110  at a predetermined cycle*N (N is an integer that is not less than 1). 
     The second steering wire group W 2  may include one or more steering wires. According to an example, the second steering wire group W 2  may include an even number of steering wires. In  FIG. 2 , it is assumed for convenience of description that the second steering wire group W 2  includes two steering wires of a 2-1-th steering wire W 2 - 1  and a 2-2-th steering wire W 2 - 2 , but this is a simple example and the technical spirit of the present disclosure is not limited by the assumption. For example, each of the steering wire groups may include two to six wires, but may include wires, the number of which is larger than six. According to an embodiment, the first and second steering wire groups W 1  and W 2  may include the same number of steering wires. In the specification, it is assumed that the first and second steering wire groups W 1  and W 2  include steering wires of the same number of two. 
     The steering wires  2 - 1  and W 2 - 2  of the second steering wire group W 2  may also adjust a tension according to a handling force applied to a steering handling device connected to ends thereof to transfer a driving force for controlling the end effector connected to the opposite ends thereof. 
     The steering wires W 2 - 1  and W 2 - 2  of the second steering wire group W 2  may be disposed spirally along the lengthwise direction of the backbone  110 . For example, the steering wires W 2 - 1  and W 2 - 2  of the second steering wire group W 2  may be disposed in the backbone  110  at a predetermined cycle*N (N is an integer that is not less than 1). 
     According to an embodiment, the steering wires in the first steering wire group W 1  and the steering wires in the second steering wire group W 2  may be disposed spirally along the lengthwise direction of the backbone  110 , and may be disposed in different directions. The, the steering wires pertaining to the same wire group may be disposed spirally in the same direction. 
     As an example, the steering wires W 1 - 1  and W 1 - 2  in the first steering wire group W 1  are disposed in a spiral shape that rotates counterclockwise in a direction A-A′, and the steering wires W 2 - 1  and W 2 - 2  in the second steering wire group W 2  are disposed in a spiral shape that rotates clockwise in an opposite direction. 
     Furthermore, the steering wires W 1 - 1  and W 1 - 2  in the first steering wire group W 1  and the steering wires W 2 - 1  and W 2 - 2  in the second steering wire group W 2  may be disposed such that distances thereof from the center of the backbone  110  in a direction of a side surface of the back bone  110  are different along the lengthwise direction of the backbone  110 . 
       FIGS. 3A, 3B, 3C, 4A, and 4B  will be referenced to describe the arrangement relationship of the steering wires in more detail. 
     Referring to  FIG. 3A , the steering wires W 1 - 1 , W 1 - 2 , W 2 - 1 , and W 2 - 2  of the first and second wire groups W 1  and W 2  may be disposed to be twisted spirally along the lengthwise direction of the backbone  110  during one cycle including C 1 , C 2 , C 3 , and C 4 . 
     Then, the steering wires W 1 - 1 , W 1 - 2 , W 2 - 1 , and W 2 - 2  of the first and second wire groups W 1  and W 2  may have the same cycle and the shape phase in the same cycle. That is, the joints and stems of the steering wires W 1 - 1 , W 1 - 2 , W 2 - 1 , and W 2 - 2  may be the same. 
     The steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  and the steering wires W 2 - 1  and W 2 - 2  in the second steering wire group W 2  may be disposed to be spaced apart from the radial center of the backbone  110  in the direction of R, and may be disposed while alternating to the inner side and to the outer side. For example, the steering wires W 1 - 1  and W 1 - 2  of the first wire group W 1  may be disposed on the outer side of the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2  during a half of the cycle of the spiral, and may be disposed on the inner side thereof during the remaining half of the cycle. 
     That is, as illustrated in  FIG. 3A , in cycle C 2 , the steering wires W 1 - 1  and W 1 - 2  of the first wire group W 1  may be disposed on the outer side of the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2  with respect to the radial center of the backbone  110 . 
     In cycle C 4 , in contrast with cycle C 2 , the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2  may be disposed on the outer side of the steering wires W 1 - 1  and W 1 - 2  of the first wire group W 1  with respect to the radial center of the backbone  110  Cycles C 1  and C 3  are sections in which the wires disposed on the outside are disposed in the inner side and the wires disposed on the inner side are disposed on the outer side. 
     In this way, the steering wires W 1 - 1  and W 1 - 2  of the first wire group W 1  and the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2  may have shapes that are twisted spirally while alternating and switching to the outer side and to the inner side. 
     Furthermore, the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  and the steering wires W 2 - 1  and W 2 - 2  in the second steering wire group W 2  may be disposed in spiral directions of different directions in all cycles. For example, referring to  FIG. 3B  illustrating section B-B′ of  FIG. 3A , the spiral direction of the wire W 1 - 2  of the first wire group W 1  is a counterclockwise direction and the spiral direction of the second wire group W 2  is a clockwise direction.  FIG. 3C  illustrates an actually implemented example. 
     Now referring to  FIG. 4A , it can be identified how the steering wires are disposed in the planar direction of the backbone  110 . As illustrated in  FIG. 4A , the steering wires W 1 - 1  and W 1 - 2  of the first wire group W 1  have the same spiral direction, the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2  have the same spiral direction, and their spiral directions are opposite to each other. 
     Referring to  FIG. 4B  illustrating the sections in the cycles of  FIG. 3A , the arrangement relationship of the wires may be understood more easily. 
     It can be identified in the four drawings at the upper side of  FIG. 4B  that the steering wires W 1 - 1  and W 1 - 2  are disposed on the outer side of the steering wires W 2 - 1  and W 2 - 2  through the illustration, in which the arrows indicating the spiral directions of the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group  110  are disposed on the outer side of the arrow indicating the spiral directions of the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2 . In contrast, it can be identified in the four drawings at the lower side of  FIG. 4B  that the steering wires W 1 - 1  and W 1 - 2  are disposed on the inner side of the steering wires W 2 - 1  and W 2 - 2  through the illustration, in which the arrows indicating the spiral directions of the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group  110  are disposed on the inner side of the arrow indicating the spiral directions of the steering wires W 2 - 1  and W 2 - 2  of the second wire group W 2 . 
     Furthermore, referring to  FIG. 4B , it can be identified that the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group  110  are spiral in the counterclockwise direction over all the entire spiral cycles and that the steering wires W 2 - 1  and W 2 - 2  of the second steering wire group  110  are spiral in the clockwise direction over all the entire spiral cycles (see the directions of the arrows). 
     Until now, the flexible mechanism  100  according to the embodiment of the present disclosure has been described. 
     Because the steering wires according to the embodiment of the present disclosure have shape that is twisted spirally along the backbone  110 , the steering wires described with reference to  FIG. 1B  may unintentionally protrude from or be introduced into one end of the backbone even when the backbone  110  is defected, whereby a phenomenon, in which the end effector is unintentionally controlled, can be minimized. 
     In more detail, due to the structure, in which the steering wires are twisted spirally along the backbone  110 , the lengths of the routes of the steering wires may be constantly maintained even when the flexible mechanism  100  is deflected. If the backbone  110  is deflected, the inner area of the backbone  110  becomes shorter than in the initial length L (see  FIGS. 1A and 1B ) and the outer area of the backbone  110  becomes longer than the initial length L (see  FIGS. 1A and 1B ). Then, because the steering wires are twisted along the backbone  110  in a spiral shape, they are influenced by all of the length changes occurring in the inner area and the outer area of the flexible backbone  110 . In other words, the wire parts located in the inner area become looser, and the wire parts located in the outer area becomes tighter. Accordingly, the loosened areas of the wires and the tightened areas of the wires are offset. Accordingly, even when the flexible mechanism  100  is deflected, the lengths of the steering wires between one end ES 1  (see  FIGS. 1A and 1B ) and an opposite end ES 2  (see  FIGS. 1A and 1B ) of the backbone  110  can be maintained constantly. In order to obtain the effect, the cycle, at which the wires are twisted along the flexible backbone, should be a multiple of 360 degrees. 
     Furthermore, the steering wires W 1 - 1  and W 1 - 2  of the first steering wire group W 1  and the steering wires W 2 - 1  and W 2 - 2  in the second steering wire group W 2  may be disposed in spiral directions of different directions. 
     Unlike this, it can be identified that there is no problem in the initial state, in which the backbone is in a straight line state as illustrated in  FIG. 5A  when all the steering wires are disposed in the same spiral direction but the straight line shape of the backbone cannot be maintained and is distorted as illustrated in  FIG. 5B  when a tension is applied to the wires of the backbone. Accordingly, it is understood that the forces, by which the steering wires disposed in the backbone  110  tend to be spread to a straight line, cause deformation of the shape of the backbone  110 . 
     Unlike this, according to the embodiment of the present disclosure, because the steering wires of the first and second wire groups W 1  and W 2  are disposed in different spiral directions, the force, by which the wires of the first wire group W 1  are spread out, and the force, by which the wires of the second wire groups W 2  are spread out, are offset even when the tension of the steering wires increase, whereby the deformation of the shape of the backbone  110  can be minimized. 
     Moreover, because the steering wires of the wire groups have spiral shapes while alternating to the inner side and the outside in a radial direction that is normal to the lengthwise direction of the backbone  110 , they can help solve the slag issue of the steering wires more. If the steering wires of the first wire group are located on the outer side of the steering wires of the second wire group over all the cycles of the spiral shapes unlike in the embodiment, the steering wires of the first wire group can be more influenced by the steering wires of the second wire group when the backbone  110  is deflected, so that the unintended control or the distortion problem of the backbone  110  may be caused. However, according to the embodiment, because the steering wires of the wire groups have spiral shapes while alternating to the inner side and to the outside in the radial direction that is normal to the lengthwise direction of the backbone  110 , the magnitudes of the offsetting force provided by the steering wires of the steering wire groups can correspond to each other. 
     Hereinafter, modifications of the above-described embodiment will be described. A description of the repeated parts will be omitted otherwise described to make the differences clear. 
       FIGS. 6A and 6B  are views illustrating a flexible mechanism according to a modification of the present disclosure. 
     Referring to  FIGS. 6A and 6B , the above-described steering wires of the steering wire groups may be disposed in a spiral groove formed on an outer peripheral surface of the backbone  110 . 
     Then, when the steering wires of the steering wire groups are disposed in the spiral groove, a spiral maintaining part  140  may be provided. The spiral maintaining part  140  may have a hollow, through which the steering wires pass, in the interior thereof, and may maintain the spiral structures of the steering wires in spite of the deflection of the backbone  110 . According to an embodiment, the spiral maintaining part  140 , as illustrated in  FIG. 6B , may have a spring shape or a hollow cylindrical shape that is shorter than the backbone  110 . 
     In more detail, the spiral maintaining part  140  may be attached (SB) to one side of the spiral groove. The steering wires may pass through the hollow of the spiral maintaining part  140  to be disposed. In this case, the steering wires may indirectly contact the backbone  110  through the spiral maintaining part  140 . Then, because the areas, by which the steering wires contact the backbone, are reduced by the spiral maintaining part  140 , a handling force can be smoothly transferred to the end effector through the steering wires even in any deflection state of the backbone  110 . 
     According to an embodiment, a sleeve  150  may be provided on an outer peripheral surface of the spiral maintaining part  140 . 
       FIG. 7  is a view illustrating a flexible mechanism according to another modification of the present disclosure. 
     Referring to  FIG. 7 , the flexible mechanism according to the modification may include a first steering wire group W 1  and a second steering wire group W 2 , which are formed on an outer peripheral surface of the backbone  110 . The elements of the first steering wire group W 1  and the second steering wire group W 1  may be the same as those described above. 
     In the modification, the first steering wire group W 1  and the second steering wire group W 2  may be formed on the outer peripheral surface of the backbone  110 , and the flexible mechanism may further include a clamp  120  that fixes the locations of the first steering wire group W 1  and the second steering wire group W 2 . 
     The clamp  120  may function to fix the wires to one side of the backbone  110 , and for example, may be a nipper, or as another example, may have a through-hole, through which the wires pass. Then, the size of the hole of the through-hole may be rather small as compared with the diameter of the wires such that the wires may be fixed. 
     The clamp  120  may fix sides of the wires in the first steering wire group W 1  and the second steering wire group W 2 . For example, the clamp  120  may be disposed at an inflection point, at which the joint of a wire is changed to a furrow. 
       FIG. 8  is a view illustrating a flexible mechanism according to another modification of the present disclosure. 
     Referring to  FIG. 8 , the backbone  110   a  according to the modification may include a plurality of backbone branches that extend in a direction that is normal to the lengthwise directions of the first steering wire group W 1  and the second steering wire group W 2 , and the plurality of backbone branches may be disposed to be spaced apart from each other along the lengthwise direction of the first steering wire group W 1  and the second steering wire group W 2 . 
     That is, while the backbone  110  has a cylindrical shape according to the embodiment, the backbone  110   a  has the plurality of branches that extend in the direction that is normal to the lengthwise directions of the first steering wire group W 1  and the second steering wire group W 2 . The first steering wire group W 1  and the second steering wire group W 1 , and the plurality of branches may be flexure hinge-coupled to each other. The lengths of the branches that connect the first steering wire group W 1  and the second steering wire group W 2  may become shorter as they go from the centers of the joints to the outside of the joints of the first steering wire group W 1  and the second steering wire group W 2 . 
     Furthermore, a spiral sleeve may be provided to fix the wires of the first steering wire group W 1  and the second steering wire group W 2 . 
     Meanwhile, according to another modification of the present disclosure, the spiral directions of the first steering wire group W 1  and the second steering wire group W 2  may be the same. That is, the spiral directions of the first steering wire group W 1  and the second steering wire group W 2  may be opposite or the same. 
     Further, according to the modification, the number of the wires having the spiral structures is not specifically limited. For example, the number of the wires may be selected from two to twelve according to a design by an ordinary person in the art. Of course, the number of the wires may be smaller than two or larger than twelve. 
       FIGS. 9 to 11B  are views illustrating a flexible mechanism according to another modification of the present disclosure. 
     The modification will be described with the assumption that the flexible mechanism is applied for a robot. Furthermore, the flexible mechanism according to the modification may include a plurality of sub-flexible mechanisms. Then, as illustrated in  FIG. 9 , the plurality of sub-flexible mechanisms may include the flexible mechanisms according to the embodiment, which have been described above. That is, a first flexible mechanism  110   a , a second flexible mechanism  110   b , and a third flexible mechanism  110   c  may be provided. The first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  may pass through a gimbal  160  that provides a degree of freedom of rotation and be connected to an end effector  170 . 
     The gimbal  160  may provide a second degree of freedom of rotation in the direction of first and second axes R 1  and R 1  to the end effector  170 . If the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  are disposed in parallel to each other, a deviation may be caused in the tensional states of the wires of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c , according to the rotational state of the gimbal  160 . In this case, an unintended handling force may also be caused. For example, when any one of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  is eccentric to the center of the rotational axis of the gimbal  160 , the tensions of the steering wires may become uneven unintentionally. 
     Accordingly, as indicated by T of  FIG. 10 , the backbones of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  may pass through the gimbal  160  while being twisted spirally. 
     Accordingly, the tensional states of the steering wires of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  may be maintained in spite of the rotation of the gimbal  160  by arranging the spiral twisting axes of the rotational axis of the gimbal  160 , and the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c.    
     Further, as illustrated in  FIG. 11A , a spiral rail part  180  may be provided to make the spiral twisting of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  smooth, and the first to third spiral rails  182 ,  184 , and  186  that provide the spiral routes of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  may be provided in the spiral rail part  180 . As illustrated in  FIG. 11B , when the spiral rail part  180  is actually manufactured and the first flexible mechanism  110   a  (denoted by  1 ), the second flexible mechanism  110   b  (denoted by  2 ), and the third flexible mechanism  110   c (denoted by  3 ) are disposed in the spiral rails, the twisting states of the first flexible mechanism  110   a , the second flexible mechanism  110   b , and the third flexible mechanism  110   c  may be maintained well. That is, the spiral rail part  180  can minimize the releasing of the spiral twisting states of the first to third flexible mechanisms due to the deflection restoring forces of the flexible backbones. 
       FIGS. 12 and 13  illustrate an experimental result for showing the excellency of the embodiments of the present disclosure. 
     First, for comparative examples, a conventional flexible mechanism including steering wires having not a spiral structure but a parallel arrangement relationship and a flexible mechanism according to the embodiment of the present disclosure were prepared. 
       FIG. 12  illustrates the case, in which the deflection of the backbone is arbitrarily derived by disposing a rail having a predetermined curvature in the flexible mechanism according to the related art. A steering handling device was not operated to simply identify whether unintended tensions of the steering wires according the deflection of the backbone were caused. In this case, it could be identified that one end of the backbone, at which an effector was disposed, was deflected in a direction of S 2  from a reference line S 1  that is the lengthwise direction of the backbone. That is, it could be identified that in the case of the steering wires disposed in parallel, an unintended tension was caused by the slag of the steering wires when the backbone was defected, and accordingly, the unintended handling force was caused in the end effector. 
     Unlike this, as illustrated in  FIG. 13 , it could be identified that there was few changes from the reference line S 1  when the flexible mechanism according to the embodiment of the present disclosure was disposed in the same rail. That is, according to the embodiment, it could be identified that the tensions on the end effector by the steering wires were maintained constantly when the backbone was deflected. 
     Although the preferred embodiments of the present disclosure have been described in detail until now, the scope of the present disclosure is not limited to the embodiments and should be construed by the attached claims. Further, it should be understood that those skilled in the art to which the present disclosure pertains may variously correct and modify the present disclosure without departing from the scope of the present disclosure.