Robot stiffness
Patent Information
- Application Number
- JP2022198552
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-12-21
- Filing Date
- 2022-12-13
- Publication Date
- 2025-09-10
AI Technical Summary
Current continuum arm robots suffer from low stiffness and reduced load-bearing capacity due to the increased number of joints, limiting their use to lightweight tasks and making them prone to deflection in longer lengths, especially when operating in confined spaces.
Incorporating an inflatable section made of elastic materials, such as rubber or silicone rubber, surrounding a passive core, which can be inflated to increase stiffness and stability by contacting the environment, allowing the robot to be securely positioned and perform tasks with enhanced load capacity.
The inflatable section enhances the stiffness and load-bearing capacity of continuum arm robots, enabling them to perform a wider range of tasks, including in confined spaces, by providing stability and reducing deflection, thus increasing their versatility and accuracy.
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Abstract
Description
[Technical Field]
[0001] The present disclosure relates to a means for stiffening a continuum-arm robot, in particular to a means for stiffening a section of a continuum-arm robot by means of an inflatable section. [Background technology]
[0002] Continuum-arm or snake-arm robots are of growing interest in several applications because they can be maneuvered into spaces not easily accessible by other robotic systems or human operators. This is due to the ability to manipulate the body with several degrees of freedom so that the end of an instrument can be precisely and easily positioned. This positioning is controlled by actuators that operate tendons within the robot so that each joint of the arm can be individually controlled to within a high degree of positional precision.
[0003] Most robotic arm systems have six or fewer degrees of freedom. However, if a task requires a greater amount of dexterity, the number of degrees of freedom required is increased. This increase in the number of degrees of freedom means that the arm can operate in a confined area, for use, for example, in repairing complex structures or in minimally invasive surgery. Continuum-arm robots are designed along two main lines: first, snake-type robots consisting of multiple rigid link sections connected either by rigid R / U / S (revolute / swivel / ball) joints or by compliant joints. Each section is composed of one or more pieces and is controlled independently of the others by on-board or remote actuation. Second, there are continuum robots consisting of a compliant backbone, whose local and global deformations are controlled by one or more actuators.
[0004] Despite the above functionality, there are problems with current designs of highly compliant robots that result from the number of joints required in the robot arm. As a result of these joints, the robot arm suffers from a lower degree of stiffness when compared to conventional six-degree-of-freedom robots. This reduced stiffness also results in reduced load-bearing capacity, reducing the interaction the arm may have with the environment in which it operates. Current technology aims to overcome this by "freezing" the system by locking actuators or by adding stiffening means to the backbone. While this may work for shorter-length robotic arms, when used with longer-length robots, the arm behaves like a long cantilever beam, and beam deflection causes significant position and navigation problems. This limits the use of such robots to light-duty tasks due to the risk of damaging the robot and / or the object it is working on. Therefore, there is a need for an improved continuum-arm robot system to overcome these problems. Summary of the Invention [Means for solving the problem]
[0005] A first aspect of the present disclosure relates to a continuum-arm robot including an instrument or effector, a tip section including a predetermined number of sections including a manipulable robotic section having multiple degrees of freedom, at least one rigidizing section including a passive core, wherein an expandable section surrounds the passive core, and a passive section including a valve for allowing fluid into the expandable outer section and a flexible conduit of a predetermined length, wherein the core of the passive section and the rigidizing section contain cables for manipulating the tip section and fluid conduits for supplying fluid to the expandable outer section.
[0006] The expandable section may be located between the instrument or effector and the tip section. The expandable section may be located in the tip section. The expandable section may be located between the tip and the passive section.
[0007] There may be multiple inflatable sections. The expandable section may be made from a resilient material such as rubber, silicone rubber, latex rubber, or the like. The expandable section may include an upper layer of elastic material and a lower layer of elastic material that join to form a balloon around the core of the rigidizing section.
[0008] The expandable section may feature proximal and distal end sections with a sealing mechanism including a gripping section attached to the disc of the stiffening section, the gripping section mating with the gripping section of the expandable section support, the expandable section support linking to the upper layer of elastic material, and the end sections further featuring a sloped section extending proximally to the gripping mechanism and connected to the inner elastic membrane, the sloped section allowing the upper elastic layer to reside within a recess formed by the sloped section when not in the expanded state, such that the outer elastic layer resides within a depression formed by the sloped section.
[0009] The stiffening section may include multiple expandable sections. The amount of fluid can be controlled within the inflatable section so that the continuum arm robot can be moved or manipulated to different locations.
[0010] The passive section may be constructed from a number of flexible pipes, with the cables and supply pipes extending through the flexible pipes. The tip section may include a six or more degree of freedom continuum arm robot of a predetermined length.
[0011] A fastening portion may be disposed around the expandable section to adjust the shape of the expandable section. The fastening portion may consist of any of the following: tape, metal structure, ribbing, and / or straps.
[0012] The expandable section may have different thicknesses, allowing the expandable section to expand non-uniformly. The expandable section may be filled with a liquid or gas to control the stiffness of the stiffening section. The inflatable section may be filled with water or liquid nitrogen.
[0013] According to a second aspect of the present disclosure, there is provided a method of using a continuum-arm robot as described above, comprising the steps of: inserting a continuum-arm robot into a cavity in a workpiece until the continuum-arm robot reaches a desired positioning; expanding the stiffening sections until the outer stiffening sections hold the continuum arm robot in place; performing a desired task using a tip section of a continuum-arm robot; collapsing a rigidified section of the continuum-arm robot; Extracting the continuum arm robot A method is provided, comprising:
[0014] Once the desired task has been performed, the inflatable section can be partially deflated so that the tip can be moved to a new position, and a second task can be performed on the new section of the workpiece before the inflatable section is deflated.
[0015] Those skilled in the art will understand that, except where mutually exclusive, a feature described in relation to any one of the above-described embodiments may be applied mutatis mutandis to any other embodiment. Furthermore, except where mutually exclusive, any feature described herein may be applied to any embodiment and / or combined with any other feature described herein. Embodiments will now be described, by way of example only, with reference to the figures, in which: [Brief explanation of the drawings]
[0016] [Figure 1a] FIG. 1a shows a prior art example of a cutaway view of a continuum arm robot. [Figure 1b] FIG. 1b is a diagram showing an example of a joint of a continuum arm robot. [Figure 2] FIG. 1 illustrates an example of the use of a continuum-arm robot according to the present disclosure. [Figure 3] FIG. 10 illustrates a flowchart of the operation of the continuum-arm robot of the present disclosure. [Figure 4] Figure 4a shows an image of the insertion of a continuum-arm robot into a workspace in its undeployed state, and Figure 4b shows an example of a continuum-arm robot in its deployed state. [Figure 5] FIG. 1 illustrates a cross-sectional view of a continuum-arm robot of the present disclosure. [Figure 6] Figure 6a shows a close-up view of the rigidized section of the continuum-arm robot of the present disclosure, and Figure 6b shows a close-up view of the distal end of the expandable section of the continuum-arm robot. DETAILED DESCRIPTION OF THE INVENTION
[0017] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.
[0018] FIG. 1a shows a prior art example of a cutaway view of a continuum arm robot. The prior art continuum arm robot includes a continuum arm robot portion 101 that is permanently integrated and extends from an actuator pack 102. The actuator pack 102 contains multiple independent actuators 103. These actuators are used to adjust the tension in the tendons that run through the continuum arm 101. The tendons are associated with joints in the arm, each of which is designed to move in response to the tightening or loosening of the tendons associated with the joint. This tightening or loosening of the tendons therefore causes the joint to contract or lengthen, which allows the continuum arm to bend. The actuator pack is shown positioned on rails or supports 104 that are positioned near the component to be tested. The actuators are further provided with multiple power and signal cables 105 that are used to power and address the actuators. Individual signals traversing the array of actuators provide control of the joints so that the continuum arm 101 can be commanded. Not shown in Figure 1 is the need for an operator with a computing device linked to the actuator to control the movement of the continuum arm and to perform the desired task. Because the continuum arm is permanently integrated into the actuator pack, if a different tool is required, it requires the use of a complete continuum arm robot system including the actuator. The computing device connected to the prior art actuator can be any suitable computing system, such as a laptop computer, featuring the requisite operating software for the robot and a control input, such as a joystick, that allows the continuum arm to be controlled.
[0019] FIG. 1b shows an example of a continuum-arm robot's joints. The arm includes multiple joints, requiring at least two cables per joint. For example, a system with three joints, each with four tendons per joint, would require 12 actuators to actuate them. Increasing the number of joints requires increasing the number of actuators, or reducing the number of tendons per joint. The highlighted joints 106, 107, and 108 can be manipulated to move in three dimensions. The joints are configured so that joints 106 and 108 can bend in the same plane relative to the center of the arm, while the plane in which joint 107 can move is offset by 90° relative to joints 106 and 108. It is through this repeated configuration of alternating joint angles, each of which results in movement in a different orthogonal plane, that the arm can be manipulated in three dimensions. Each joint in the arm has a limit to the amount it can bend, which is dictated by the arm's design and the materials used. The bending limits at each joint set requirements for properties such as the minimum bending radius and the torque required to cause a resulting change in the joint. It is the presence of space at the joints that allows the joints to move and the ease of joint movement results in the arm's low stiffness compared to other robotic arms of the same length. This is because the structural behavior of a snake-type robotic manipulator can be likened to that of a cantilever beam under load, since the system is fixed at one end to a base with an actuation puck, and the remainder of the arm is used to navigate through the environment without any other points of contact. In this situation, any load applied to the body and / or tip of the snake-type robot, including the snake-type robot's own weight, imposes a significant deflection from the ideal position. At the end of the arm, an instrument or probe is positioned that is designed to perform one or more functions once the continuum arm is in place.The head of a continuum-arm robot is often provided with an optical system so that an operator can see the head as it is inserted into a component and control it as it performs its task. The optical system is also often coupled to a lighting system. Control cables for instruments, power connectors for the lighting system, and optical cables can usually run through the center of the joint in the continuum arm. This has the benefit of protecting the cables from any potential damage.
[0020] FIG. 2 shows an example of a continuum-arm robot according to the present disclosure. In this example, a continuum arm 201 is inserted into a cavity 202 of an object to be inspected or repaired. The continuum-arm robot 201 contains several sections with movable joints that allow the robot to be manipulated into position. The continuum arm section closest to the actuator and farthest from the head of the continuum arm is a passive section 203. The passive section is a non-controllable section that is flexible and allows the control tendons and power and device supplies to pass through while protecting them. The middle section of the continuum-arm robot consists of an expandable section 204. The expandable section in this example includes three expandable systems, but the continuum-arm robot may contain any suitable number of expanding systems. The expanding systems extend from the outer surface of the continuum-arm robot and expand to contact the surface wall of the object to be inspected. The balloon has a contact area with the wall 208 through which the inflation of the inflatable section exerts a force on the wall of the workspace or cavity 202. The presence of the inflation system positions the continuum arm robot at the center of the cavity of the object being worked on, because the inflatable section creates a force on the outside of the cavity wall used to position the arm. However, depending on the nature of the inflation system, the continuum arm section can be positioned anywhere the inflatable system supports. The active section 205 is positioned at the head of the continuum arm robot near the actuator or is the head of the continuum arm robot. The continuum arm robot has an end effector 206 that can inspect a target inspection area 207 of the object being worked on. The inflatable system can be made of an elastic material such as rubber, silicone rubber, latex rubber, or any other suitable material that will be apparent to one skilled in the art.The size of the expanding mechanism can be actively controlled, which allows the robotic system to adapt to the working conditions of the continuum robot, whether that be entering and exiting a small size cavity or operating in a large cavity.
[0021] While the inflatable section is shown above as being intermediate the passive and active sections, the inflatable section may also be located in the active section. This may be done by separating the sections to feature the inflatable section, or by placing the inflatable section around the active section. Alternatively, the inflatable section may be located between the active section and the end effector. In these cases, the inflatable section may be inflated once the effector is in position to hold the effector in place during operation.
[0022] During use, when the continuum robot is inserted, the expanding systems are at their natural size, i.e., the outer diameter of the expanding system is designed to be the same as the overall diameter of the continuum robot. This allows for easy navigation of the continuum robot to a desired location. However, the expandable sections may extend a small distance from the diameter of the continuum robot, as this would be the case if the expandable sections moved around the active section. During the operational phase, the size of the expanding system is actively adjusted by expanding the volume by pumping a fluid, such as air, water, and / or oil, into the volume between the outer and inner surfaces of the expanding system. The fluid for this can be supplied through a tube either in the conduit at the center of the snake or outside the conduit. Sensors can be used to determine whether the expandable sections are correctly inflated. This can be done through the use of pressure sensors. With proper parameter design and material selection, an expanding system can secure a continuum robot within a confined tube / cavity. This securement improves the rigidity of the end effector, thus increasing its versatility and accuracy. In addition, the use of an expanding system can also provide a good solution for enabling a continuum robot to adapt to confined environments with different shapes. Furthermore, the use of an expanding system is beneficial to the operation of a continuum arm robot because it allows the robot arm to be fixed in place so that it cannot move while the end effector is in use. Because the continuum arm is held in place, it means that the size of the continuum robot in general can be minimized. This is because it is not necessary to increase the size of the robot to create greater strength and resistance to counteract forces on the robotic arm.Providing contact between the continuum robot and the chamber / wall during operation reduces the effect of the cantilever length in the system, which therefore has the effect of increasing system stiffness. The ability to inflate and deflate the expansion system means that the system can be used reliably and repeatedly in different locations, because the robot can be safely inserted into and removed from the cavity.
[0023] The operating principle of the above-described expanding system continuum arm robot is shown in FIG. 3. The first step 301 is to insert the continuum arm robot into the cavity, which will orient the tool to its working position. During this process, the rigidization sections remain at their natural size, i.e., without balloon inflation. This means that the continuum arm robot can be easily inserted into the chamber / cavity. The use of a long passive section allows the inflation system to be positioned near the head of the continuum arm robot. If desired, the passive section can also feature an inflation system to minimize contact between the continuum arm robot and the cavity. In the second step 302, once the tip or head of the continuum arm robot is in place at the desired tip or head position, the inflation system can be activated. To do this, air / fluid is pumped into the rigidization inflation mechanism. The expansion of the inflation system causes the outer wall of the inflation system to come into contact with the wall of the cavity. The pressure and friction of the outer wall of the inflation system in contact with the wall of the cavity has the effect of fixing or locking the continuum robot within the cavity. In a third step 303, the inflation section is inflated, and the continuum arm robot is firmly positioned within the cavity so that the tip section can perform its desired task. The use of the inflation system increases the rigidity of the system, allowing the robot arm to perform a greater range of tasks than it would be able to perform without the presence of the inflation system. In a fourth step 304, once the operation performed by the robot head is completed, the inflation system can be deflated. Deflation is accomplished by venting the air or fluid from the balloons, either by opening a valve in the case of air, or alternatively by pumping out the air or fluid used to fill the inflation system. This causes the balloons of the inflation system to shrink back to their natural size.The continuum-arm robot is thus in the same state it was in when it was inserted. The fifth step 305 is the extraction of the continuum-arm robot from the cavity. This is possible because the continuum-arm robot has been returned to the state it was in when it was inserted into the cavity, so the robot can exit through the same opening it entered through, for example an inspection hole in a gas turbine engine.
[0024] FIG. 4a shows a diagram of the insertion of a continuum arm robot 401 into a cavity 402 in a component 403. The continuum arm robot has an actuator head 404, an expandable section 405, and a passive section 406. The continuum arm robot is inserted into the cavity through a doorway 407. In the image, the expandable section is not expanded, so the strength of the tip of the continuum arm robot is provided by the strength of the continuum arm robot's joints and sections. In such a state, there is a limit to the load or capacity of the end of the actuator. FIG. 4b shows an example of a continuum arm robot in its deployed state. In this state, the expandable section 405 is expanded so that the outer section of the expandable section 405 contacts the wall of the cavity. In this state, the expandable section can exert a force on the cavity, which in turn exerts a force on the continuum arm robot that propagates through the expandable section. Thus, the expandable section of the continuum-arm robot in the deployed state acts as a stiffening mechanism. With this expandable section in place, the stiffness of the continuum-arm robot is increased, and therefore the load that can be applied to the end of the robot, or to an actuator at the end, is increased. As a result, the robot has an increased load capacity for the same size. This therefore acts to increase capacity.
[0025] FIG. 5 shows a cross-sectional view of the continuum arm robot of the present disclosure. The figure shows a closer look at three separate sections of the continuum arm robot of the present disclosure. In this figure, the body of the continuum arm robot is constructed from three independent sections, each with its own function. This section consists of a passive section 501, which is the flexible length of the robot where there are no controls. The passive section has suitable rigidity to ensure easy transport of the continuum robot into the work area. The passive section is designed to be capable of supporting actuation cables and other deliverable tubes and pipes as required by the tip, as well as conduits for supplying fluids required by the inflation mechanism. The passive section can be of any suitable length to allow the continuum arm robot to access the required area. A rigidifying section 502 is located between the passive section 501 and the tip section 503. In this example, the rigidization section is also passive because it is not operated by an actuator. Surrounding this section are either single or multiple inflatable sections. These inflatable sections consist of a skin that stretches around the continuum arm section in that area. The skin must form a sealed section around the continuum arm section so that it can be inflated to support against the cavity wall. The skin must be made of a material that can deform under pressure from the fluid used to inflate the balloon, yet is strong and tear-resistant enough so that it does not tear if it gets caught on an uneven surface. The robotic section has inlets and / or outlets for supplying and removing fluid into and out of the balloon. The final section of the continuum robot is the tip section, which is the controllable section of the robot, in this example a section of the continuum robot with six degrees of freedom.The end of the tip section may have an actuator or tool depending on the task and process that is required to be performed. The tip section may be of any suitable length and have any suitable number of movable sections within it to perform the required task.
[0026] To ensure that the entire continuum robot can be delivered through the inspection hole into the chamber, the rigidization section should be flexible enough to allow the robot to be maneuvered into space. Therefore, a structure combining multiple backbones and a rigidization mechanism consisting of an inflatable structure is used. Such requirements can be achieved by utilizing a thin rigidization mechanism constructed from two layers of hyperelastic coating covering several disk sections of the backbone. Thus, the rigidization section can have the same properties as a conventional continuum robot, but can have fluid actively pumped in to increase its diameter to fill the cavity and thus increase the robot's rigidity. A detailed example of this is shown in FIG. 6a, which shows a close-up view of the rigidization section of the continuum-arm robot of the present disclosure. Within the rigidizing section 601 of the continuum-arm robot are several disks 602 and 603 to provide the necessary rigidity and flexibility to deliver and support the continuum robot for insertion into the cavity work area. This section is divided into two ends relative to the actuator: a proximal end 604 and a distal end 605. These ends support and secure the inflatable sections to the continuum robot. There may be one or more of the inflatable sections provided on the rigidizing section. Figure 6b shows a close-up view of the distal end of the inflatable section of the continuum-arm robot. The end contains an inflatable sealing mechanism to support the inflatable section. This sealing mechanism includes a gripping section 606 attached to the disk of the rigidizing section of the continuum robot. The gripping section connects to the inflatable section support. The inflatable section support is designed to link to the inflatable balloon section, providing a looser connection than linking the inflatable balloon section directly to the disc of the rigidizing section. However, as one skilled in the art will appreciate, there are several ways in which the inflatable balloon of the rigidizing section may be bonded to the rigidizing section body, including bonding the balloon directly to the disc. The inflatable section support is bonded to a superelastic membrane 607 that forms the outer layer of the balloon.The end section features a sloped section that extends proximally to the gripping mechanism. The sloped section allows the superelastic layer to surround the disk of the support section without increasing the diameter of the arm, as any change in arm diameter would reduce the accessibility of the continuum arm robot and even result in the section getting caught on the edge of the cavity. Coupled to the sloped section is a lower layer 608 of superelastic material that forms the inner section balloon of the stiffening section.
[0027] The tip section may have a number of instruments and / or actuators attached to it. In addition to the instruments or actuators, which require their own controls and are required to run along the body of both the passive and rigid sections of the continuum-arm robot, there are also control cables for the actuators required for six-degree-of-freedom manipulation of the tip section. Therefore, the passive and rigid sections require careful design so that they have pathways to allow the feeding of these cables without increasing the overall diameter of the continuum-arm robot. One way to do this could be to use several linked flexible rods in the passive section, with the joints at the ends of the rods becoming flexible joints that connect to form a flexible backbone. In the rigid section, as shown in Figures 6a and 6b of the present disclosure, the long flexible rod is replaced by an air-fluid pathway that contains all the necessary cables in the center of this section.
[0028] An advantage of the system is that the thickness of the balloon wall can be tailored to provide the optimal degree of expansion and structural integrity. Thicker walls are known to expand less but are less susceptible to puncture in the working environment. It may even be possible to tailor the balloon thickness. Thus, the balloon thickness can be adjusted across its length to provide asymmetric expansion. For example, a thicker wall at one edge would cause the balloon to expand in a U-shape, which can be used to match the shape of the cavity into which the continuum arm robot is inserted. Thus, the inflatable section can be tailored to fit the cavity. An alternative way to control the balloon shape is the use of fasteners. These fasteners can be placed on the outside of the balloon structure to provide asymmetric expansion. The fasteners can be of any suitable structure or nature, as would be apparent to one skilled in the art, and may include the use of thick tape, metal structures, ribs, or straps. A further means of adjusting the stiffness of the stiffening sections can be to expand them using different gases or fluids so that the expansion profile and structural integrity are optimized. For example, balloons can be filled with water to provide greater stiffness than if the balloon were filled with air. Alternatively, the balloons can be supercooled using liquid nitrogen or other mechanisms to provide increased stiffness in the environment. To increase the functionality of the robot, the stiffness of the structure can be controlled in the environment by actively adjusting the air flow rate and pressure. Thus, the movement of the robot in the environment can be controlled. For example, balloons can be slightly deflated to allow the robot to be deployed even further into the engine; these balloons can then be re-inflated when the instrument is in the correct location relative to the damage requiring repair.
[0029] It will be understood that the present invention is not limited to the embodiments described above, and that various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be used separately or in combination with any other feature, and the present disclosure extends to and includes all combinations and subcombinations of one or more features described herein. [Explanation of symbols]
[0030] 101 Continuum arm robot part, continuum arm 102 Actuator Pack 103 Actuator 104 Rails or supports 105 Power and Signal Cables 106 joints 107 Joints 108 joints 201 Continuum Arm, Continuum Arm Robot 202 Cavity 203 Passive Section 204 Inflatable Section 205 Active Section 206 End Effector 207 Inspection Area 208 Wall 401 Continuum Arm Robot 402 Cavity 403 Components 404 Actuator head 405 Inflatable Section 406 Passive Section 407 Entrance / Exit 501 Passive Section 502 Rigid Section 503 Tip Section 601 Rigid Section 602 Disk 603 Disk 604 Proximal end 605 Distal end 606 Gripping Section 607 Superelastic Membrane 608 Lower layer
Claims
1. A continuum-arm robot, Equipment and a tip section at a tip of the continuous-arm robot, the tip section including a manipulable robotic section having multiple degrees of freedom; a stiffening section including an internal passive core, an expandable section having at least one expandable volume surrounding the passive core, and a valve for introducing a fluid into the expandable section; a passive section including a length of flexible conduit; the passive core and the stiffening section contain a cable for operating the tip section and a fluid conduit for supplying the fluid to the inflatable section; the stiffening section is between the passive section and the tip section; the inflatable section comprises an upper layer of elastic material and a lower layer of elastic material joined together to form a balloon around a core of the stiffening section, and proximal and distal end sections having sealing mechanisms including gripping sections attached to discs of the stiffening section; the gripping section couples with a gripping section of an inflatable section support; the inflatable section support links to the upper layer of elastic material; the end section includes a sloped section extending proximally relative to the gripping mechanism and connected to an inner elastic membrane; the sloped sections cause the upper layer of elastic material to be positioned within the recess formed by the sloped sections such that the upper layer of elastic material is positioned within the recess when not in an expanded state. Continuum arm robot.
2. The continuous-arm robot of claim 1 , wherein the expandable section is made from an elastic material.
3. The continuous-arm robot of claim 1 , wherein the stiffening section comprises a plurality of expandable sections.
4. The continuous-arm robot of claim 3 , wherein the amount of fluid in the plurality of inflatable sections is controllable, allowing the continuous-arm robot to be moved or manipulated into different positions.
5. The continuous-arm robot of claim 1 , wherein the passive section comprises a plurality of flexible tubes, the cables and supply tubes extending through the flexible tubes.
6. The continuum-arm robot of claim 1 , wherein the tip section comprises a continuum arm with six or more degrees of freedom.
7. The continuous-arm robot of claim 1 , wherein a fastening portion is around the expandable section to adjust the shape of the expandable section.
8. The continuous-arm robot of claim 7 , wherein the fastening portion comprises a tape, a metal structure, a rib, and / or a band.
9. The continuous-arm robot of claim 1 , wherein the expandable section has a different thickness that allows the expandable section to expand non-uniformly.
10. The continuous-arm robot of claim 1 , wherein the expandable section is filled with a liquid or gas to control the stiffness of the stiffening section.
11. The continuous-arm robot of claim 10 , wherein the inflatable section is configured to be filled with water or liquid nitrogen.
12. 10. A method of using the continuum-arm robot of claim 1, comprising: inserting the continuum-arm robot into a cavity in a workpiece until the continuum-arm robot reaches a desired position; expanding the stiffening section until the stiffening section holds the continuous-arm robot in place; performing a desired task using a tip section of the continuum-arm robot; collapsing the rigidized section of the continuum-arm robot; extracting the continuum-arm robot; A method comprising:
13. 13. The method of claim 12, wherein once the desired task is performed, the inflatable section is partially deflated so that the tip section can be moved to a new position, and a second task can be performed on the new section of the workpiece before the inflatable section is deflated.
14. The continuous-arm robot of claim 1 , wherein the expandable section is made from at least one of rubber, silicone rubber, and latex rubber.