Patent Publication Number: US-2023139801-A1

Title: Insertion tool with flexible spine

Description:
This application claims the benefit of U.S. Provisional Application No. 63/274,421 filed Nov. 1, 2021, which is incorporated herein by reference in its entirety 
    
    
     FIELD OF THE DISCLOSURE 
     The present subject matter relates generally to tools for inspecting an environment and/or performing maintenance operations on a component within the environment, and methods for forming thereof. 
     BACKGROUND 
     Snake-arm robots are highly flexible robots suited for working in confined and hazardous spaces. Driven by wire ropes, snake-arm robots are able to traverse cluttered environments and conduct activities such as inspection, fastening, and cleaning when integrated with various tools. 
     Guide tubes are typically cylindrical pathways used to direct a variety of tools and fasteners. Guide tubes may be installed to ensure accuracy and precision during a secondary process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various needs are at least partially met through provision of the INSERTION TOOL WITH FLEXIBLE SPINE described in the following detailed description, particularly when studied in conjunction with the drawings. A full and enabling disclosure of the aspects of the present description, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which refers to the appended figures, in which: 
         FIG.  1 A  is a perspective view of a portion of an insertion tool in a tensioned state according to some embodiments; 
         FIG.  1 B  is a section view of the portion of the insertion tool of  FIG.  1 A  according to some embodiments; 
         FIG.  1 C  is a side view of the portion of the insertion tool of  FIG.  1 A  according to some embodiments; 
         FIG.  2 A  is a perspective view of the portion of the insertion tool of  FIG.  1 A  in a bent position according to some embodiments; 
         FIG.  2 B  is a section view of the portion of the insertion tool of  FIG.  2 A  according to some embodiments; 
         FIG.  2 C  is a side view of the portion of the insertion tool of  FIG.  2 A  according to some embodiments; 
         FIG.  3 A  is a top perspective view of a link according to some embodiments; 
         FIG.  3 B  is a bottom perspective view of the link of  FIG.  3 A  according to some embodiments; 
         FIG.  4 A  is a perspective view of a fixturing assembly according to some embodiments; 
         FIG.  4 B  is a close-up view of links in the fixturing assembly of  FIG.  4 A  according to some embodiments; 
         FIG.  5    illustrates a flow diagram of a method for forming an insertion tool according to some embodiments; and 
         FIGS.  6 A and  6 B  are side views of an insertion tool with an integrated spine according to some embodiments. 
     
    
    
     Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present teachings. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present teachings. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. 
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the present disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. 
     The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” “almost,” and “substantially” are not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin. These approximating margins may apply to a single value, either or both endpoints defining numerical ranges, and/or the margin for ranges between endpoints. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
     In general, the present subject matter relates to an insertion tool and a method of forming thereof. The tool may be used for inspecting an environment (e.g., inspecting internal components with the tool to produce images) and/or performing maintenance operations. In some embodiments, the tool may comprise a snake arm robot and/or a rigidizable guiding tool. In some embodiments, the tool may be useful in inspecting and performing maintenance on machinery with narrow channels such as a gas turbine engine. 
     In some embodiments, the devices and methods described herein replace the prior art connectors (e.g. hinge pins or other sliding or pivoting features) in guide tubes and other circumferential tools like an arc-snake with a flexible spine to connect the links of the tool. In some embodiments, an insertion tool with a flexible spine described herein improves the correct positing of the tool in a combustor compared to guide tubes with individual hinges between links. In some embodiments, the spine and the body may be fixed together through a direct fixing method or by using an additional core in one of the bodies. Methods to fix may include bonding, welding, screws, rivets, crimping, encapsulation within one or more bodies, overmolding, brazing, shrink fits, heating staking, fastening (e.g. with spins or screws), and snap fits. In some embodiments, the spine may be integrated with the body and formed from a single material, such as through an additive manufacturing process that forms both the spine and one or more links through depositing layers of material in a specific sequence based on a computer model. 
     In some embodiments, the devices and methods described herein provide robustness for manually operated rigidizable guide tubes and snake-arm robots, at a low price. In some embodiments, the devices and methods may generally be used for slender manipulators with a high number of degrees of freedom that allows the device to be inserted along a path or around an obstacle. The device has been shown to be effective in prototype form and addresses both cost and robustness issues with other hinge designs in a number of robotics products. The teachings described herein are applicable to rigidizable guide tubes and planar snake-arm robots. Lowering the costs of advanced inspection devices can greatly increase the adoption rates of the advanced inspection devices in the field, allowing the manufacturer/servicer to see more data from product lines. 
     In some embodiments, individual hinges of a guide tube are replaced with a single flexible spine or multiple short spine strips between the links. The design is relatively economical to produce in long lengths which keeps the costs of longer devices down and helps to expand potential opportunities to deploy. 
     In some embodiments, the use of the spine removes the requirement to hold the joint stable to maintain a high torsional stiffness and maintain accuracy compared to existing designs, allowing devices to be made smaller and therefore access more areas. As the spine removes the need to hold a force across the joint between the bodies, a force is only needed to form the body into a shape rather than hold it together, increasing the robustness of the device. In some embodiments, the use of a flexible spine also allows a desired shape of the insertion tool to be achieved without having to tolerance each component very highly. 
     In some embodiments, a fixed arc or other datum surface is used during fixturing/assembly of the insertion tool. The fixturing channel comprising a fixed arc or datum may substantially increase the accuracy of the device without complex secondary manufacturing operations or forcing high-cost precision manufacturing techniques for constituent parts. In some embodiments, a rigidizable guide tube with a flexible spine may include fewer tension ropes/lines to simplify the assembly process and control during deployment. 
     In some embodiments, in an insertion tool, a pair of links are allowed to move about an axis relative to each other without a sliding or rotating pivot using a flexure hinge/flexible spine. During manufacture, the final shape of the arm may be constrained in a fixture during fixing of the flexible spine to the arm to ensure that the final form of the device is accurate and independent of the sum totals of errors in the individual links. 
     In some embodiments, a method includes placing a plurality of links, a flexible spine, and a line assembly into a channel of a fixturing assembly, the line assembly being inserted through line guides in each of the plurality of links. The method also includes pulling, via the line assembly, the plurality of links into a tensioned state in the channel. The method also includes affixing the flexible spine to each of the plurality of links in the channel and while in the tensioned state. 
     In some embodiments, an insertion tool apparatus includes a plurality of links arranged in a sequence and a flexible spine affixed to the plurality of links. The apparatus also includes a line assembly inserted through line guides in each of the plurality of links, the line assembly being configured to actuate the plurality of links from a free state to a tensioned state. 
     The foregoing and other benefits may become clearer upon making a thorough review and study of the following detailed description. Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures. In  FIG.  1 A , a perspective view of a portion of an insertion tool  100  in a tensioned state is provided.  FIGS.  1 B and  1 C  are views of the insertion tool  100  in section view and side view respectively.  FIGS.  2 A,  2 B,  2 C  illustrates the insertion tool  100  in a bend position in a perspective view, section view, and side view respectively. In some embodiments, the insertion tool  100  may comprise a snake arm robot and/or a rigidizable guiding tool. In some embodiments, the insertion tool  100  comprises a distal end configured to reach into narrow areas, such as the interior of a turbine engine, while being manipulated from a proximal end. In some embodiments, service and inspection tools such as clamps, cameras, cleaning tools, etc. may be attached to the distal end of an insertion tool  100  to perform various functions while the insertion tool  100  is inserted. In some embodiments, the proximal end of the insertion tool  100  may be mounted to a control system, such as a gear rack, for controlling the movement of the insertion tool  100 . In some embodiments, the proximal end may further include a tension controller for affecting the tension of a tension line assembly  130  inserted through the links  110  of the insertion tool  100 . The insertion tool  100  may be actuated between a tensioned state and a free state via the tension line assembly  130 . 
     The insertion tool  100  includes a plurality of links  110  arranged in sequence from the proximal end to the distal end of the insertion tool  100 . The links  110  may each include an interior opening that collectively defines a core  112  through the links  110  for supporting and enabling the operation of a wide variety of service and/or inspection tool implements through the links  110 . In some embodiments, each link  110  may be formed of molded plastic, additively manufactured plastic, overmolded plastic, metal, etc. The interior of the links  110  further includes a spine slot  116  for the placement of a flexible spine  120  that connects two or more links  110 . In some embodiments, as shown in  FIG.  1 B and  2 B , the spine slots  116  in links  110  may be narrower in the center  116 b and wider towards the two ends  116 a and  116 c of a link  110  to allow flex of the flexible spine  120 . In some embodiments, the flexible spine  120  may be affixed to one or more links  110  via bonding, welding, heat staking, fasteners (e.g. pins, screws), snap fits, over-molding, brazing, shrink fits, and the like. In some embodiments, the flexible spine  120  may be affixed to the link  110  at or near the center of the spine slot  116 . In some embodiments, a flexible spine  120  may instead be affixed to an exterior or interior surface of links  110  without a spine slot  116 . In some embodiments, a polymer or other moldable material may be molded over the links  110  and the flexible spine  120  or parts thereof. In some embodiments, links  110  may be molded in place on the flexible spines. In some embodiments, the insertion tool  100  may be formed by shaping and affixing the links  110  to the flexible spine  120  according to the method described with reference to  FIG.  5   . 
     In some embodiments, the flexible spine  120  may be a continuous piece of material that extends through all links  110  of an insertion tool  100 . In some embodiments, the flexible spine  120  may include a plurality of segments with each segment being a continuous piece of material that is affixed to two, three, four, or more links  110  of the insertion tool  100 . Generally, the flexible spine  120  is one or more strips or rods of material without any joints or pivots. In some embodiments, the flexible spine  120  may be formed of metal, spring steel, plastic, carbon fiber, woven Kevlar, or other high tensile material. In some embodiments, the flexible spine  120  may have an elastic modulus of between 5-210 MPa. In some embodiments, the flexible spine  120  is configured to secure the links  110  together while allowing the links  110  to pivot relative to each other when tension or external bending force is applied. In some embodiments, the flexible spine  120  is shaped to provide one degree of freedom to the movement of the tip of the insertion tool  100  and prevent axial rotation of the links  110  relative to each other. In some embodiments, the flexible spine  120  may be a flat strip to limit the rotation of the links  110  relative to each other. In some embodiments, the flexible spine  120  and the shape of the links  110  are configured to limit the bend of the insertion tool  100  in one or both directions 
     The links  110  further include line guides  114  through which a line assembly  130  (e.g., see  FIG.  4 A ) may be inserted through one or more of the links  110  to bias the links  110 . In some embodiments, lines extending through line guides  114  within each of the links  110  may provide a biasing force to press the links  110  together during fixturing and as holding force along the bottom (e.g., bottom surface  113 ) of the links  110  for holding the insertion tool  100  in the tensioned state during operation. Generally, the line assembly  130  is configured to be tensioned to compress the plurality of links  110 . In some embodiments, when the line assembly  130  is tensioned, the links  110  of the insertion tool  100  are compressed to a tensioned state forming a rigidized or semi-rigidized arc with a predetermined curvature. In some embodiments, the line assembly  130  may comprise a single line connected on two ends to the proximal end and looped through the distal end of the insertion tool  100  or two lines each attached to the distal end and the proximal end of the insertion tool  100 . 
     In some embodiments, the links  110  each includes an indentation  121  and a protrusion  122  on opposite ends  124  and  126  of the link  110  near the bottom surface  113 , opposite the flexible spine  120 , together forming a stop feature. The indentation  121  is configured to engage the protrusion  122  of an adjacent link  110  when the insertion tool  100  moves from a free or bend state as shown in  FIGS.  2 A-C  to a tensioned or closed state as shown in  FIGS.  1 A-C . In some embodiments, when tension is applied to the line assembly  130  to compress the links  110 , the stop features counteract the force applied by the line assembly  130  to hold the insertion tool  100  in a predetermined shape. Generally, the stop features (indentation  121  and protrusion  122 ) limit the curvature of the insertion tool  100  and allow the shape formed by the fixturing process described with reference to  FIGS.  4 A,  4 B, and  5    to be reproduced in free space. In some embodiments, a link  110  may include other recesses, protrusions, and openings for increasing structural strength, reducing weight, engaging with a drive mechanism, engaging with external guides, and/or providing access to the interior of the link  110 . 
     It will be appreciated that the insertion tool  100  may be used in any compatible machine across different industries. While reference is made herein with respect to turbofan engines and gas turbine engines specifically, one of ordinary skill in the art will recognize that the inherent flexibility of the insertion tool  100  allows for inspection and maintenance in different industrial machines of varying sizes. 
     Referring now to  FIGS.  3 A and  3 B , a link  110  of an insertion tool  100  according to some embodiments is shown. The link  110  includes a top surface  111  and a bottom surface  113 . In some embodiments, when the insertion tool  100  is in the tensioned state such as shown in  FIGS.  1 A-C , the top surface  111  corresponds to the extended side and the bottom surface  113  corresponds to the compressed side of the insertion tool  100 . In some embodiments, the bottom surface  113  and/or the top surface  111  of each of the plurality of links  110  comprises a rounded surface for aligning the links  110  during fixturing. The top surface  111  comprises an opening  117  to the spine slot  116  for affixing a flexible spine  120  inserted into the spine slot  116  to the link  110 . In some embodiments, adhesive, screw, fastener, heat, light, etc. may be applied to a flexible spine  120  in the spine slot  116  via the opening  117  prior to or during the fixturing process described with reference to  FIGS.  4 A-B  and  5 . In some embodiments, the top surface  111  may comprise a plurality of openings to access the spine slot  116  and/or the inserted flexible spine  120 . In some embodiments, the opening  117  for affixing a flexible spine  120  may be centered, off-centered, or side-facing. 
     The spine slot  116  is located beneath the top surface  111  and configured to receive a flexible spine  120  inserted through the ends  124  and  126  of the link  110 . In some embodiments, the spine slot  116  is narrower at or near the center and wider towards the ends of the link  110  to allow flex of the affixed flexible spine  120  within the spine slot  116 . In some embodiments, the flexible spine  120  may only be secured to the link  110  at or near the center of the spine slot  116  as shown in  FIGS.  1 B and  2 B . In some embodiments, the spine slot  116  may be omitted, and the flexible spine  120  may instead be affixed to the top surface  111  or a wall of the core  112  with a slot structure. 
     The core  112  is configured to support and enable the operation of a wide variety of service and/or inspection tool implements through the links  110 . In some embodiments, the core  112  may be separated into multiple openings of various sizes and shapes depending on the application. The line guides  114  are each configured to receive a line  130 a,  130 b of a line assembly  130  for biasing the link  110  of an insertion tool  100 . In some embodiments, the line is inserted through but not attached to the line guides  114 . 
     In some embodiments, the sides of a link  110  may further include a plurality of drive features  118  configured to engage a gear rack for driving the movement of the insertion tool  100  and wing protrusions  119  for engaging with a tool guide to ensure the tool stays on track during operation. In some embodiments, the drive features  118  and/or the wing protrusions  119  may be used to align the links  110  during the fixturing process. 
     In some embodiments, a link  110  of an insertion tool  100  may omit one or more features described with references to  FIGS.  3 A-B , such as the spine slot  116 , the core  112 , the drive feature  118 , and the wing protrusion  119 . 
     Referring now to  FIGS.  4 A and  4 B , a fixturing assembly  400  for forming and shaping an insertion tool  100  according to some embodiments is shown. The fixturing assembly  400  includes a channel  410  with a specified predefined curvature. The channel  410  is defined by an outer ring  430  of a base  420  and inner ring  440  removably attached to the base  420 . The inner ring  440  is actuatable by a clamp actuator  445  to affect the width of the channel  410 . In some embodiments, the outer ring  430  comprises a fixed wall of the channel  410  and the inner ring  440  comprises a moveable clamp of the channel  410 . In some embodiments, the channel  410  may instead be defined by a fixed inner ring and a movable outer ring. In some embodiments, the inner ring  440  may be of any length up to the length of the outer ring  430 . In some embodiments, the inner ring  440  may comprise a plurality of segments that together forms the length of the channel  410 . In some embodiments, segments of the inner ring  440  may be added or removed from the base  420  based on the desired length of the insertion tool  100  being formed. In some embodiments, the channel  410  is an open channel and the links  110  may be dropped into the channel from the top. In some embodiments, the channel  410  may comprise a tube, and the links  110  may be inserted through one or both ends of the tub. 
     During fixturing, links  110  for forming an insertion tool  100  are placed in the channel  410 . In some embodiments, the channel  410  is curved and the links  110  are placed into the channel  410  with the bottom surface  113  facing the side of the channel  410  having a smaller diameter (e.g., inner ring  440 ) and the top surface  111  (e.g., near a spine slot  116 ) facing the side of the channel  410  having a larger diameter (e.g., outer ring  430 ). When pressure is applied to the links  110  via the moveable clamp (e.g., inner ring  440 ) of the channel  410 , the links  110  are shaped to rotate to a position that radially aligns the links  110  within the channel  410 . In some embodiments, the surfaces of the channel  410  that contacts the links  110  have friction coefficients of less than 0.3 such that the links  110  may easily slide and rotate to align when tension and/or pressure is applied to the links  110 . 
     In some embodiments, tension is applied to the links  110  in the channel  410  via a line assembly  130  including one or more lines inserted through line guides  114  of the links  110 . A tension controller (not shown) may be positioned at an outer ring opening  435  of the channel  410  to pull the line assembly  130  to apply tension to the links  110 . In some embodiments, the applied tension may match the force applied by the line assembly  130  when the fixtured insertion tool  100  is in the tensioned state in free space. 
     In some embodiments, the links  110  are affixed to a flexible spine  120  when the links  110  have been radially aligned and while tension is applied to push the links  110  together in the channel  410 . In some embodiments, a wall of the channel  410  (e.g., as defined by outer ring  430 ) comprises one or more openings  432  for accessing the links  110  placed in the channel  410  for affixing the links  110  to the flexible spine  120  inside the channel  410  while the links  110  are aligned and tensioned in the channel  410 . In some embodiments, an adhesive material may be applied to affix the flexible spine  120  to the link  110 , and tension may be applied to hold the links  110  in place until the adhesive material fully dries or cures. In some embodiments, the flexible spine  120  may be affixed to the links  110  via bonding, welding, heat staking, fasteners (e.g. pins, screws), snap fits, over-molding, brazing, shrink fits, and the like. In some embodiments, the fixturing assembly  400  may be used in the method described with reference to  FIG.  5   . 
     In some embodiments, in addition to or in place of a movable clamp, the channel  410  may include one or more grooves that engage protrusions such as the wing protrusions  119  and the drive features  118  on the links  110  to radially align the links  110  placed into the channel  410 . In some embodiments, the channel  410  may comprise a tub, and the links  110  may be inserted through one or both ends of the tub. 
     Referring now to  FIG.  5   , an exemplary method  500  is illustrated for forming an insertion tool  100  with a plurality of links  110  and a flexible spine  120 . 
     At step  501 , a flexible spine  120  and a line assembly  130  are inserted into a sequence of links  110 . In some embodiments, each link  110  may include a spine slot  116  and one or more line guides  114 . In some embodiments, the flexible spine  120  may comprise a continuous single material or a plurality of segments. In some embodiments, spine slots  116  may be absent in the links  110  and the flexible spine  120  may instead be placed adjacent to the links  110  in a channel  410  of a fixturing assembly  400 . In some embodiments, step  501  may occur after step  503  and/or step  505 . For example, the links  110  may be placed in the channel  410  and aligned prior to the flexible spine  120  and/or the line assembly  130  being inserted through the links  110 . 
     At step  502 , an adhesive material is optionally applied to the flexible spine  120  and the links  110  before the links  110  are placed into the channel  410 . In some embodiments, an adhesive may be deposited via the opening  117  on the top surface  111  of each link  110 . In some embodiments, the links  110  with the adhesive material are placed into the channel  410  prior to the adhesive being fully cured such that the flexible spine  120  may still move and slide relative to the links  110  in steps  503 ,  504 , and  505 . In some embodiments, step  502  may be omitted for embodiments using other means of affixing the flexible spine  120  to the links  110 . 
     At step  503 , the links  110 , the flexible spine  120 , and the line assembly  130  are placed into a channel  410  of a fixturing assembly  400 . In some embodiments, the channel  410  is curved and the links  110  are placed into the channel  410  with the bottom surface  113  contacting a side of the channel  410  having the smaller diameter. In some embodiments, at step  501 , the links  110  are not yet pushed against each other or fully aligned radially. In some embodiments, the channel  410  of the fixturing assembly  400  includes one or more moveable clamps (e.g., clamp actuator  445  and inner ring  440 ) and a fixed wall (e.g., outer ring  430 ). In some embodiments, the channel  410  includes one or more grooves that engage wing protrusions  119  and/or drive features  118  on the plurality of links  110  to align the links  110  placed into the channel  410 . 
     In step  504 , the line assembly  130  applies tension to pull the links  110  against each other into a tensioned state in the channel  410 . In some embodiments, in a tensioned state, the stop features (e.g. protrusion  122  and indentation  121 ) of adjacent links  110  engage each other. In some embodiments, the line assembly  130  is pulled until the links  110  stop moving in response to further tension. In some embodiments, the force applied through the line assembly  130  is the same or proximately the same as the force applied to the links  110  by the line assembly  130  to move the insertion tool  100  into a tensioned state while in free space after the insertion tool  100  is fixtured. 
     In step  505 , pressure is applied to the links  110  to push the links  110  against a wall of the channel  410 . In some embodiments, a clamp formed by the inner ring  440  of the fixturing assembly  400  applies force via the bottom surface  113  of the links  110  to push the top surface  111  of the links  110  against the outer ring  430 . In some embodiments, the clamp may instead be formed by a portion of the outer ring  430  to push the links  110  against the inner ring  440 . In some embodiments, the bottom surface  113  and/or the top surface  111  of each of the links  110  include a rounded surface configured to rotate and align the links  110  when pressure is applied to the top and/or bottom surfaces  111 ,  113  of the links  110  in the channel  410 . In some embodiments, step  505  may be omitted in embodiments where the channel  410  includes one or more grooves for engaging wing protrusions  119  on the sides of the links  110  for alignment. 
     In step  506 , the flexible spine  120  is affixed to the links  110  while the links  110  are tensioned and aligned in the channel  410 . In some embodiments, the flexible spine  120  is affixed to the links  110  through adhesives, bonding, welding, screws, rivets, crimping, encapsulation within one or more bodies, over-molding, brazing, shrink fits, heating staking, fastening, and/or snap fits. In some embodiments, means for affixing such as fastener, adhesive, heat for welding, or UV light for curing may be applied to the flexible spine  120  via openings (e.g., openings  117 ) on a wall of the channel  410  of the fixturing assembly  400  contacting the top surfaces  111  of the links  110 . After step  506 , the links  110 , the flexible spine  120 , and the line assembly  130  form a fixtured insertion tool  100  configured to be actuated from a free state to a tensioned state, where the tensioned state reproduces to the curvature defined by the channel  410  of the fixturing assembly  400 . In some embodiments, in the free state, the insertion tool  100  may take a variety of shapes based on external forces such as gravity and contact with external surfaces. 
     Referring now to  FIGS.  6 A and  6 B , an insertion tool  600  with an integrated spine according to some embodiments is shown. The insertion tool  600  includes a distal end  630  configured to hold a tool and a proximal end  610  that may be fixed to a base for controlling the insertion tool  600 . Links  611  are formed by openings  612  on the body  625  of the insertion tool  600  between the ends  610 ,  630  and the connecting material between the links  611  forms a flexible spine  620 . The links  611  are each shaped such that when tension is applied and the stop features of the links come in contact with each other, a predefined curvature is achieved. In some embodiments, the insertion tool  600  may be formed as a single piece of plastic and/or may be additively manufactured. The additive manufacturing process may form the shapes of the individual links based on the desired curvature. The insertion tool  600  further includes a line guide  614  for inserting a line assembly (e.g., line assembly  130 ) for actuating the links  611  from a free state to a tensioned state. 
     All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
     Further aspects of the disclosure are provided by the subject matter of the following clauses: 
     A method of forming an insertion tool comprises placing a plurality of links, a flexible spine, and a line assembly into a channel of a fixturing assembly, the line assembly being inserted through line guides in each of the plurality of links; pulling, via the line assembly, the plurality of links in into a tensioned state in the channel; and affixing the flexible spine to each of the plurality of links while in the tensioned state. 
     The method of any proceeding clause further comprising applying, with the fixturing assembly, pressure to the plurality of links to push the plurality of links against a wall of the channel to radially align the plurality of links. 
     The method of any preceding clause wherein at least one of a bottom surface and a top surface of each of the plurality of links comprises a rounded surface configured to align the plurality of links when pressure is applied in the channel. 
     The method of any preceding clause wherein the channel is curved and the plurality of links are placed into the channel with the bottom surface facing a side of the channel having a smaller diameter 
     The method of any preceding clause wherein the channel of the fixturing assembly comprises one or more moveable clamps and a fixed wall. 
     The method of any preceding clause wherein the channel comprises a groove that engages protrusions on the plurality of links to align the plurality of links placed into the channel. 
     The method of any preceding clause wherein one or more surfaces of the channel that contacts the plurality of links have friction coefficients of less than 0.3. 
     The method of any preceding clause wherein a wall of the channel comprises one or more openings for accessing the plurality of links placed in the channel for affixing the plurality of links to the flexible spine. 
     The method of any preceding clause wherein the flexible spine is affixed to the plurality of links through at least one of adhesive, bonding, welding, screws, rivets, crimping, encapsulation within one or more bodies, over-molding, brazing, shrink fits, heating staking, fasteners, and snap fits. 
     The method of any preceding clause further comprising applying an adhesive material to the flexible spine before placing the plurality of links into the channel and wherein affixing the flexible spine comprises curing the adhesive material on the flexible spine. 
     The method of any preceding clause wherein each of the plurality of links comprises an opening on a surface contacting a wall of the channel, wherein the flexible spine is affixed to each of the plurality of links via the opening. 
     The method of any preceding clause wherein each of the plurality of links comprises a spine slot through which the flexible spine is inserted. 
     An insertion tool apparatus comprises a plurality of links arranged in a sequence; a flexible spine affixed to the plurality of links; and a line assembly inserted through line guides in each of the plurality of links, the line assembly being configured to actuate the plurality of links from a free state to a tensioned state. 
     The apparatus of any preceding clause wherein each of the plurality of links comprises a spine slot through which the flexible spine is inserted. 
     The apparatus of any preceding clause wherein the spine slot of a link of the plurality of links is narrower at a center and wider at two ends. 
     The apparatus of any preceding clause wherein a top surface of a link of the plurality of links comprises an opening through which the flexible spine in the spine slot is affixed to the link. 
     The apparatus of any preceding clause wherein the flexible spine is affixed to the plurality of links through adhesives, bonding, welding, screws, rivets, crimping, encapsulation within one or more bodies, over-molding, brazing, shrink fits, heating staking, fasteners, or snap fits. 
     The apparatus of any preceding clause wherein each of the plurality of links comprises an indentation on a first end and a protrusion on a second end, and the indentation is configured to engage the protrusion of an adjacent link when the plurality of links are in the tensioned state. 
     The apparatus of any preceding clause wherein sides of each of the plurality of links comprise a protrusion configured to engage with a tool guide and/or a channel of a fixturing assembly. 
     An insertion tool apparatus comprises a line assembly and an additively manufactured body having a distal end, a links portion, and a proximal end. The links portion of the body having a plurality of openings that define a plurality of links and connecting material forming a flexible spine connecting each of the plurality of link in sequence. The line assembly being configured to actuate the plurality of links from a free state to a tensioned state. 
     The apparatus of any preceding clause wherein each of the plurality of links comprises an indentation on a first end and a protrusion on a second end, and the indentation is configured to engage the protrusion of an adjacent link when the plurality of links are in the tensioned state. 
     The apparatus of any preceding clause wherein sides of each of the plurality of links comprise a protrusion configured to engage with a tool guide and/or a channel of a fixturing assembly. 
     The apparatus of any preceding clause wherein the proximal end and the plurality links comprise openings that form a line guide through which the line assembly is inserted. 
     A method for forming an insertion tool comprises additively manufacture, based on a computer model, a body of an insertion tool having a distal end, a links portion, and a proximal end. The links portion of the body having a plurality of openings that define a plurality of links and connecting material forming a flexible spine connecting each of the plurality of link in sequence. The method further comprises inserting a line assembly into the body, the line assembly being configured to actuate the plurality of links from a free state to a tensioned state. 
     The method of any preceding clause wherein a bottom surface of each of the plurality of links formed by additive manufacturing comprises an indentation on a first end and a protrusion on a second end, and the indentation is configured to engage the protrusion of an adjacent link when the plurality of links are in the tensioned state. 
     The method of any preceding clause wherein sides of each of the plurality of links formed by additive manufacturing comprise a protrusion configured to engage with a tool guide and/or a channel of a fixturing assembly. 
     The method of any preceding clause wherein the proximal end and the plurality links formed by additive manufacturing comprise openings that form a line guide through which the line assembly is inserted. 
     This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.