An underactuated core-column continuum robot for narrow-space tasks

Abstract

The application discloses a kind of underactuated core column type continuum robot for narrow space task, belong to multiple degrees of freedom redundant continuum robot technical field.It includes: drive device, through the combination of multiple motor control drive rope winding and unwinding, realize the flexible movement of mechanical arm, reach the expected working pose.Mobile guide rail propulsion platform, linear motion is executed in guide range, and mechanical arm is moved to specified operation range.Continuum robot arm main body, by N identical mechanical arm units, is divided into M joint sections;Adopt rigid-flexible coupling mode, combine universal joint structure and core column structure, flexible deflection between joints, torsional stiffness and overall load capacity are improved;End effector, according to operation demand, carries out diversified task.The robot provided by the application has the advantages of strong flexibility, large length-diameter ratio, strong torsional capacity, strong environmental adaptability and the like, and can meet the detection and operation and maintenance operation demand in narrow unstructured space.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of multi-degree-of-freedom redundant continuous robots, and relates to an underactuated core column type continuum robot for a narrow space task. BACKGROUND

[0002] With the rapid development of industrial heavy equipment and aerospace technology, the demand for work in narrow unstructured environments is increasing, such as aerospace engine detection, aircraft wing tank detection, and nuclear power plant in-service equipment operation and maintenance. Taking the aircraft wing tank as an example, as a core component of the aircraft, it needs to be detected before and after flight, and its internal structure is narrow and limited, with many intersecting ribs, which is prone to leakage, combustion and explosion hazards. Currently, maintenance personnel manually carry out detection and troubleshooting work, which has the problems of low detection efficiency, long cycle, high intensity, and difficulty in troubleshooting fault sources, so there is an urgent need for an equipment to replace maintenance personnel to perform detection tasks.

[0003] Traditional industrial robots cannot enter narrow spaces for work due to size and flexibility limitations. Existing continuum robots with narrow space work capability can generally include universal joint structure and core column structure continuum robots, and other structures such as paper folding, pure flexibility, and active motor drive structure cannot complete such work tasks due to factors such as large size and insufficient stiffness. The continuum robot based on the universal joint requires a corresponding drive for each joint, greatly increasing the number of drives and the overall weight and design difficulty. The continuum robot based on the core column structure is prone to buckling instability under a large driving force, and its torsional stiffness is weak, which is prone to torsional deformation under its own weight and load.

[0004] Combining the universal joint structure and the core column structure can form a new type of continuum robot for narrow space work. The universal joint structure can provide torsional stiffness, axial deformation stiffness, and repeat positioning accuracy; the core column structure can complete the force transmission relationship between two adjacent universal joints, provide bending deformation stiffness, and realize a few drive structures. The combination of the two can avoid buckling instability caused by axial deformation of the core column and significantly increase the torsional stiffness, while significantly reducing the number of active drives. This structure can efficiently complete the work in narrow and restricted unstructured environments, and has important scientific research value and practical significance. SUMMARY

[0005] To solve the above problems, the present application provides an underactuated core column type continuum robot for a narrow space task. The continuum robot introduces a core column into the universal joint structure to form a rigid-flexible coupled structure, which has the advantages of high flexibility, strong torsional resistance, large length-diameter ratio, strong environmental adaptability, and few drives, and can meet the detection work task in narrow space.

[0006] To achieve the above object, the present application provides the following technical solutions.

[0007] An underactuated core column type continuum robot for narrow space tasks, the underactuated core column type continuum robot comprising a continuum robot main body 1, a guide wire mechanism 2, a guide wire cone 3, a driving device 4, a linear feed platform 5, and specifically as follows:

[0008] The driving device 4 comprises driving cables and motors, a plurality of driving cables are connected with a plurality of motors through the guide wire mechanism 2, the rotation of the motor is controlled to make the driving cable elongate or shorten, and through the combination of winding and unwinding of different driving cables, the control of the target posture of the continuum robot is realized.

[0009] The guide wire mechanism 2 is connected with the motor of the driving device 4 and connected with the driving cable, and is mostly a driving pulley or a screw rod module.

[0010] The guide wire cone 3 is large at the back and small at the front, is fixed on the front fixed plate of the driving device 4 through bolts, and is hollow inside for passing through the driving cable.

[0011] The linear feed platform 5 is placed below the driving device 4 and is used to drive the driving device 4 and the robot main body 1 to move forward or backward within the lead range. One end of the driving cable is connected with the continuum robot main body 1, and the other end is connected with the driving device 4 through the guide wire mechanism 2.

[0012] The linear feed platform 5 carries the continuum robot main body 1 to move to the working range, the driving device 4 drives the corresponding driving cable to contract through the guide wire mechanism 2, the continuum robot main body 1 starts to adjust its own posture, after passing through the first layer of rib plates of the wing 6, the linear feed platform 5 continues to move, the continuum robot main body 1 continues to adjust its own posture, starts to pass through the second layer of rib plates of the wing 6, and so on, until reaching the target working position.

[0013] Further, the continuum robot main body 1 comprises N mechanical arm units 7 connected in sequence and having the same structure, a core column 11, and a universal joint 10, each mechanical arm unit 7 is uniformly provided with a plurality of driving through holes 16 for passing through the driving cable in the circumferential direction and penetrates through the entire continuum robot main body 1, and the number of the driving cables is the same as the number of the through holes. Among them, every N / M mechanical arm units 7 constitute a joint segment 8, the entire continuum robot main body 1 has M joint segments 8, adjacent mechanical arm units 7 are connected through the universal joint 10, the core column 11 passes through the hollow part of the universal joint 10 and is fixed in the boss 12 of the adjacent mechanical arm unit 7. The number of the universal joints 10 in the same joint segment 8 is equal to the number of the core columns 11. Specifically:

[0014] The first mechanical arm unit 7 at the head end is fixed to the lead cone 3 by bolts, and the end effector is connected to the mechanical arm unit 7 at the end of the continuum mechanical arm body 1 by bolts.

[0015] The upper surface and the lower surface of each mechanical arm unit 7 are symmetrically provided with a shoulder 9. The shoulder 9 is symmetrically provided with a countersunk threaded hole 13 along the vertical central axis direction.

[0016] The upper surface and the lower surface of each mechanical arm unit are symmetrically provided with a boss 12. The distance between the shoulders 9 is greater than the side length of the boss 12, and the distance between the boss 12 and the left and right shoulders 9 is equal. A core column hole slot 14 is arranged above the boss 12 along the central axis direction, and the boss is uniformly provided with four tight threaded holes 15 in the circumferential direction, and the core column hole slot 14 is in communication with the tight threaded hole 15.

[0017] The adjacent two mechanical arm units 7 are connected by a universal joint 10. The universal joint 10 is uniformly arranged with four threaded through holes in the circumferential direction, and when the threaded through holes of the universal joint 10 are coaxially aligned with the countersunk threaded holes 13 on the shoulders 9 of the mechanical arm units 7, the flexible deflection between the adjacent two mechanical arm units is realized by connecting through threaded shafts.

[0018] The core column 11 is selected from a plurality of flexible nickel-titanium alloy rods, the two ends of which pass through the core column hole slots 14 of the adjacent two mechanical arm units 7 and are fastened from four directions via the tight screws 19 in the tight threaded holes 15. The length of each core column 11 is equal to the distance between the upper and lower surfaces of the adjacent two mechanical arm units 7. It should be noted that the greater the diameter of the core column 11, the greater the stiffness of the joint segment 8, and the smaller the diameter of the core column 11, the more flexible the joint segment 8. In actual application, the joint segment 8 close to the lead cone 3 usually adopts a large-diameter core column 11, and the joint segment 8 close to the end of the continuum mechanical arm body 1 usually adopts a small-diameter core column 11.

[0019] Further, one end of the mechanical arm base is fixed on the table surface of the lead cone 3 by bolts, and the other end is connected to the mechanical arm unit 7 through the universal joint 10.

[0020] Further, each mechanical arm unit 7 is provided with a through slot 17 penetrating the upper and lower surfaces to realize weight reduction.

[0021] Further, the end effector 22 includes but is not limited to a camera, a mechanical gripper, a searchlight, etc.

[0022] Further, the continuum mechanical arm body 1 can also be installed on an industrial robot, and the two are cooperated to realize more flexible and accurate spatial motion.

[0023] The working process of the under-actuated core-column continuum robot for narrow space tasks is as follows: the maintenance personnel operate the linear feed platform to move to the front of the wing 6 to be inspected, and control the multiple motors in the drive device 4 on the advanced controller (PC) interface to drive the wire mechanism 2 to move. The corresponding drive cables shrink, and the continuum robot arm body 1 adjusts its own posture under the action of the drive cables to pass through the first layer of ribs of the wing 6. At this time, the linear feed platform 5 continues to move, and the continuum robot arm body 1 continues to adjust its position and posture by coordinating the retraction and extension of the drive cables to complete the second crossing or turning movement. Similarly, the continuum robot reaches different inspection operation points in the wing 6 by adjusting its own posture multiple times, and the end effector 22 feeds back the inspection information to the advanced controller (PC) interface to provide a reference for the maintenance personnel.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts a rigid-flexible coupling method to introduce a nickel-titanium alloy rod (core column) into the design of the universal joint structure, taking into account the advantages of both. The rigidity provided by the nickel-titanium alloy rod limits the maximum bending angle of the universal joint structure, and the characteristics of the universal joint limit the torsion of the nickel-titanium alloy rod. The two cooperate to limit each other, so that the robot arm has a large load capacity. While ensuring the flexible movement of the robot arm body, the working length and anti-torsion rigidity of the continuum robot arm are greatly improved, and a certain self-aligning ability is provided.

[0026] (2) The present invention introduces a nickel-titanium alloy rod as a flexible connector between two adjacent robotic arm units, avoiding the drawback that the conventional continuum robotic arm with a universal joint structure requires full drive, thereby greatly reducing the number of drives and the size of the drive device.

[0027] (3) The present invention can realize the switching of different task requirements by combining nickel-titanium alloy rods of different stiffness. The design of the arm body is relatively small when changing to different tasks, and the implementation is simple.

[0028] (4) The robot described in the present invention has the characteristics of small unit diameter, large main body length, large length-diameter ratio, small mass, compact and reasonable layout, replicability and scalability, and can adapt to different working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of an under-actuated core-column continuum robot for narrow space tasks provided by the present invention performing an operation;

[0030] Figure 2 It is a structural schematic diagram of the continuum robotic arm main body provided by the present invention; Figure 2 (a) is the isometric view of the main structure; Figure 2 (b) is the front view of the main structure;

[0031] Figure 3 is a structural schematic diagram of a mechanical arm unit provided by the present application;

[0032] Figure 4 is a top view of the mechanical arm unit provided by the present application;

[0033] Figure 5 is a structural schematic diagram of a "mouth" shaped block of a universal joint provided by the present application;

[0034] Figure 6 is a structural schematic diagram between the upper and lower surfaces of two adjacent mechanical arm units provided by the present application;

[0035] Figure 7 is a schematic diagram of the application of a continuum mechanical arm combined with an industrial robot provided by the present application.

[0036] In the figure: 1 continuum mechanical arm main body; 2 wire guide mechanism; 3 wire cone; 4 driving device; 5 linear feed platform; 6 wing; 7 mechanical arm unit; 8 joint segment; 9 convex shoulder; 10 universal joint; 11 core column; 12 boss; 13 countersunk threaded hole; 14 core column hole slot; 15 locking threaded hole; 16 driving through hole; 17 through slot; 18 rotating shaft; 19 locking screw; 20 base; 21 industrial robot arm; 22 actuator. DETAILED DESCRIPTION

[0037] The present application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of changes and improvements can be made. These are within the scope of the present application.

[0038] The present application provides an underactuated core column type continuum robot for narrow space tasks, as shown in Figure 1 includes:

[0039] The driving device changes the length of the different driving cables by controlling the forward and reverse rotation of the multiple motors in cooperation with the wire guide mechanism, realizes flexible movement of the mechanical arm, and reaches the expected working pose.

[0040] The moving guide rail advancing platform increases the degree of freedom of the mechanical arm, performs linear feed and backward movement within the lead range, and moves the mechanical arm to the specified working range.

[0041] The continuum manipulator body is composed of N structural identical manipulator units and is divided into M joint segments 8; the continuum manipulator body adopts a rigid-flexible coupling mode, and the joints can flexibly deflect; the nickel-titanium alloy rod is passively bent as a flexible framework, and the two ends are respectively fixed on the upper and lower surfaces of the adjacent two manipulator units. This design not only plays a role in reducing the force transmission of the driving device, but also improves the torsional stiffness and further increases the overall load capacity;

[0042] The end effector includes a mechanical gripper, a camera and the like, and can perform diversified tasks according to the work requirements. The robot disclosed in the application has the advantages of high flexibility, large length-diameter ratio, high torsional capacity and high environmental adaptability, and can meet the detection and operation and maintenance work requirements in narrow unstructured space.

[0043] Specifically, it includes a continuum manipulator body 1, a wire guide mechanism 2, a wire cone 3, a driving device 4 and a linear feed platform 5. The wire cone 3 is large in front and small in back, and the rear end is fixed on the front fixed plate of the driving device 4 by bolts, and is hollow, and the driving rope passes through it. The driving device 4 is connected to the continuum manipulator body 1 through the wire guide mechanism 2 and can control the rotation of the motor to make the driving cable stretch or shorten. Through the combination of winding and unwinding of different driving cables, the control of the target posture of the continuum robot is realized to adapt to different working environments. The linear feed platform 5 is placed at the bottom of the driving device 4 and can drive the driving device 4 and the continuum manipulator body 1 to complete the feeding or retreating movement within the lead range. When the robot in the example works, the linear feed platform 5 carries the continuum manipulator 1 to move to the working range, under the drive of the driving device 4, through the conversion of the wire guide mechanism 2, the driving cable is stretched or contracted, the continuum manipulator body 1 starts to adjust its own posture, after passing through the first layer of rib plates of the wing 6, the linear feed platform 5 continues to move, the continuum manipulator body 1 continues to adjust its own posture, starts to pass through the second layer of rib plates, and so on, until reaching the target work position.

[0044] As Figure 2As shown, the continuum manipulator body 1 is composed of N manipulator units 7 with the same structure connected in sequence, which are divided into M joint segments 8, and each joint segment 8 includes N / M manipulator units 7. Each joint segment 8 with two degrees of freedom of pitch and yaw requires at least three ropes for complete constraint, so the number of drive cables for each group of joint segments 8 is at least three. The drive cables are evenly arranged circumferentially along the vertical axis, with a total of 3M cables. The number of drive cable through holes is the same as the number of drive cables, which are divided into M groups. The three drive cables in each group pass through the last manipulator unit of the corresponding joint segment 8 and are limited by wire clamps to prevent them from malfunctioning due to accidental falling off. The bosses 9 of two adjacent manipulator units are staggered, and the connecting line between the two pairs of bosses 9 is vertical, and is connected to the "mouth"-shaped block of the universal joint 10 through a rotating shaft with a thread. The core column 11 is a nickel-titanium alloy rod, which serves as a flexible skeleton. Its head and tail ends are respectively inserted into the core column holes 14 set on the upper and lower surface bosses 12 of two adjacent robot arm units, and are fixed by screwing in two pairs of set screws 19.

[0045] Figure 3 is a schematic structural diagram of the robotic arm unit 7, Figure 4 This is a top view of the robotic arm unit 7. In the initial state, the axes of the various units of the robotic arm are on the same horizontal line, and the continuum robotic arm body 1 is horizontal. As shown in the figure, the upper and lower surfaces of the robotic arm unit are symmetrically provided with bosses 9, and the bosses 9 are symmetrically provided with countersunk threaded holes 13 in a direction perpendicular to the central axis. The upper and lower surfaces of the robotic arm unit 7 are symmetrically provided with bosses 12, and the bosses 12 are provided with core column slots 14 for fixing nickel-titanium alloy rods along the central axis of the robotic arm body. Four tightening threaded holes 15 are opened around the bosses 12 perpendicular to the central axis, and the core columns are fixed by tightening screws. The robotic arm unit 7 is evenly provided with multiple drive through holes 16 around the circumference, and the drive cables pass through the through holes 16, and the number of through holes is the same as the number of drive cables. The control of different motion states of the robotic arm is achieved by retracting and extending different drive cables. Under the premise of meeting the strength requirements, the robotic arm unit 7 can achieve the purpose of weight reduction by providing a through slot 17. Preferably, the specification of the threaded hole on the boss 9 is M3, the specification of the fastening threaded hole 15 on the boss is M2, and the number of the drive cables and through holes is 9.

[0046] like Figure 5 As shown, four through-holes are evenly distributed around the universal joint 10, divided into two pairs. One pair mates with the shoulder 9 on the bottom surface of the i-th robotic arm unit 7, and the other pair mates with the shoulder 9 on the top surface of the (i+1)-th robotic arm unit 7. It is important to note that a gap must be left between the universal joint 10 and the shoulder 9 of the robotic arm unit 7 to ensure flexible pitch and yaw motion. The four circumferential edges of the universal joint 10 are rounded to prevent interference with the shoulder 9 during motion.

[0047] In another instance, Figure 6 The schematic diagram shows the structure between the upper and lower surfaces of two adjacent robotic arm units. As shown, the two adjacent robotic arm units 7 are connected by a universal joint 10. The four circumferential through-holes of the universal joint 10 mate coaxially with two pairs of bosses 9. A threaded shaft 18 screws into the through-holes to enable flexible rotation of the universal joint 10. The robotic arm body utilizes a rigid-flexible coupling approach, incorporating a nickel-titanium alloy rod into the design of the universal joint 10 as a flexible framework. The two ends of the nickel-titanium alloy rod are inserted into the core post slots 14 provided on the upper and lower bosses of the two adjacent robotic arms and then secured by set screws 19. When the robotic arm bends under external load, the nickel-titanium alloy rod passively bends in accordance with the bending trend of the robotic arm body. Once the external force is removed, the rod provides a certain degree of self-centering capability. This rigid-flexible coupling structure significantly reduces torsion of the continuum robotic arm about its central axis. It is important to note that the spacing between the bosses 9 should be slightly larger than the width of the universal joint 10, and the diameter of the core post slot 14 should be slightly larger than the diameter of the nickel-titanium alloy rod to minimize the negative effects of friction. Preferably, the specification of the threaded rotating shaft is M3×6, and the specification of the set screw is M2×4.

[0048] like Figure 7 As shown, the base 20 of the robotic arm, in addition to being directly connected to the drive unit, can also be bolted to the end of an industrial robotic arm 21. This enhances the flexibility and adaptability of the continuum robotic arm, making it more stable and effective when carrying heavy objects and performing delicate operations, adapting to different tasks and working environments. The end of the continuum robotic arm is equipped with different types of actuators 22 (such as grippers, cameras, suction cups, sensors, etc.), which can be replaced or combined according to specific task requirements, thereby achieving diverse functions.

[0049] During operation, the linear feed platform 5, carrying the drive unit 4 and the continuum manipulator body 1, reaches the operating range. The multiple motors in the drive unit 4 work in concert, controlling the forward and reverse rotation of the motors to drive the wire mechanism, adjusting the retraction and extension of the multiple drive cables, thereby enabling the manipulator to move flexibly within a confined space. During this process, the universal joint 10 structure plays an active role, rotating under pressure to provide flexible "pitch" and "yaw" degrees of freedom. The nickel-titanium alloy rod plays a flexible role, deforming under pressure, providing a certain degree of torsional stiffness and self-alignment for the manipulator body. This limits the maximum bending angle of the manipulator unit, preventing accidents caused by self-contact, and also improving the load capacity of the continuum manipulator.

[0050] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in the present invention are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of the present application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit the present invention to being implemented by adopting the above specific details.

[0051] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. An underactuated core-column continuum robot for narrow space tasks, characterized by: The under-actuated core column type continuum robot comprises a continuum robot arm body (1), a wire mechanism (2), a wire cone (3), a driving device (4), and a linear feed platform (5); The driving device (4) includes a driving cable and a motor. One end of the driving cable is connected to the continuum robot arm body (1), and the other end is connected to the motor through a wire mechanism (2). The motor is controlled to rotate to extend or shorten the driving cable. By combining different retraction and extension of the driving cables, the target posture of the continuum robot is controlled. The conductor cone (3) is larger at the rear and smaller at the front, and is fixed to the front fixing plate of the driving device (4). The interior is hollow for passing the driving cable. The linear feed platform (5) is placed below the driving device (4) and is used to drive the driving device (4) and the robot arm body (1) to feed or retreat within the lead range; The continuum robot arm body (1) comprises N robot arm units (7), core columns (11), and universal joints (10) that are connected in sequence and have the same structure. Each robot arm unit (7) is evenly provided with a plurality of driving through holes (16) for passing driving cables in the circumferential direction and passes through the entire continuum robot arm body (1); adjacent robot arm units (7) are connected through universal joints (10), and the core columns (11) pass through the hollow part of the universal joints (10) and are fixed in the bosses (12) of the adjacent robot arm units (7); the number of the driving cables is the same as the number of the through holes (16); every N / M robot arm units (7) constitute a joint segment (8), and the entire continuum robot arm body (1) has a total of M joint segments (8); the number of universal joints (10) in the same joint segment (8) is equal to the number of core columns (11); In the continuum robotic arm body (1): Each robot arm unit (7) is symmetrically provided with bosses (9) on its upper and lower surfaces; the bosses (9) are symmetrically provided with countersunk threaded holes (13) along a direction perpendicular to the central axis; Bosses (12) are symmetrically provided on the upper and lower surfaces of each robotic arm unit; the distance between the bosses (9) is greater than the side length of the bosses (12), and the distance between the bosses (12) and the left and right bosses (9) is equal; a core column hole groove (14) is provided above the bosses (12) along the central axis direction, and tightening threaded holes (15) are uniformly provided around the bosses, and the core column hole groove (14) is connected to the tightening threaded hole (15); The universal joint (10) is provided with threaded through holes evenly arranged in the circumference. When the threaded through holes of the universal joint (10) are coaxially aligned with the countersunk threaded holes (13) on the boss (9) of the robot arm unit (7), they are connected via a threaded shaft to achieve flexible deflection between two adjacent robot arm units. The core column (11) is made of a plurality of flexible nickel-titanium alloy rods, both ends of which pass through the core column slots (14) of two adjacent robotic arm units (7) and are fastened from four directions via set screws (19) in the fastening threaded holes (15); the length of each core column (11) is equal to the distance between the upper and lower surfaces of the two adjacent robotic arm units (7).

2. The under-actuated core-column continuum robot for narrow space tasks according to claim 1, characterized in that: In the continuum robot arm body (1), the first robot arm unit (7) at the head end is fixedly connected to the wire cone (3), and the end effector (22) is connected to the end robot arm unit (7) of the continuum robot arm body (1).

3. The under-actuated core-column continuum robot for narrow space tasks according to claim 1, characterized in that: The joint segment (8) close to the wire cone (3) usually adopts a core column (11) with a large diameter, and the joint segment (8) close to the end of the continuum robot arm body (1) usually adopts a core column (11) with a small diameter.

4. The under-actuated core-column continuum robot for narrow space tasks according to claim 1, characterized in that: Each robot arm unit (7) is provided with a through slot (17) that passes through the upper and lower surfaces.

5. The under-actuated core-column continuum robot for narrow space tasks according to claim 2, characterized in that: The end effector (22) includes but is not limited to a camera, a robotic gripper, and a searchlight.

6. The under-actuated core-column continuum robot for narrow space tasks according to claim 1, characterized in that: The continuum robot arm main body (1) is mounted on the industrial robot arm, and the two cooperate to achieve flexible and accurate spatial movement.

7. The under-actuated core-column continuum robot for narrow space tasks according to claim 1, characterized in that: The guide wire mechanism (2) is a driving pulley or a lead screw module.

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