Modular detection robot for straight square pipes based on star-shaped tensegrity unit and walking method

Abstract

The present invention discloses a linear square pipeline modular detection robot based on a star-shaped tensegrity unit and a walking method. The robot includes a plurality of identical three-bar star-shaped tensegrity unit modules and connection nodes therebetween. The three-bar star-shaped tensegrity unit modules are connected end to end, and the connection nodes are rigidly connected; the central driving rods of each unit are collinear in the initial equilibrium state. The deformation of each three-bar star-shaped tensegrity unit is achieved by the elongation and shortening of the central driving rod. The present invention utilizes the principle of the longitudinal wave method to reasonably control the elongation and shortening of the central rod of each unit, and relies on the friction between the robot and the pipeline wall to realize the robot moving forward or backward in a straight line in the pipeline. The tensegrity pipeline detection robot has a simple control method, does not block the pipeline when crawling through the pipeline, is lightweight and efficient, has strong impact resistance, and has strong modular assembly, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to a tensegrity pipeline detection robot technology, in particular to a linear square pipeline modular detection robot based on a star-shaped tensegrity unit and a walking method. Background Art

[0002] As cities continue to expand and become more modernized, municipal pipelines are becoming more and more dense and complex, and the workload of management is also increasing. However, manual cleaning and maintenance of pipelines is time-consuming and labor-intensive. Pipeline robots can penetrate deep into the pipelines, overcome the difficulty of narrow pipeline space, and replace manual cleaning and maintenance of pipelines, which will greatly reduce the difficulty of pipeline maintenance and improve the efficiency of pipeline cleaning and maintenance.

[0003] For pipeline robots used for linear pipeline detection, existing robots have various shapes, structures and crawling methods. For example, wheels are used to squeeze the pipeline wall, magnets are used to make the robot crawl along the pipeline wall, and multi-legged robots are used to crawl in the pipeline. However, existing robots are often large in mass and size, which makes the robots consume too much energy and occupy the pipeline when working, limiting their application potential.

[0004] The tensegrity robot is lightweight, efficient, and impact-resistant, and has good application prospects.

[0005] According to the literature review, the "Kinematic Analysis of Three-Bar Star-Shaped Tensegrity Deployable Structure" published in the Journal of Harbin Engineering University in March 2021 described the composition and folding and unfolding analysis of the three-bar star-shaped tensegrity structure, but did not combine it with a robot and remained at the theoretical analysis level.

[0006] The paper "DuCTT: a Tensegrity Robot for Exploring Duct Systems" published at the 2014 IEEE International Conference on Robotics & Automation (ICRA) describes an existing tensegrity pipeline exploration robot, DuCTT, which consists of two tetrahedrons and relies on cable drive to achieve motion control. However, it has a large number of control cables and requires the extension and retraction of rods to achieve the movement of the robot, so the control strategy is relatively complex. Summary of the invention

[0007] In view of the above technical problems, the present invention provides a linear square pipeline modular detection robot and walking method based on a three-rod star-shaped tensegrity unit, which is simple to control, easy to assemble, lightweight and efficient, and does not block the pipeline during operation.

[0008] Technical solution:

[0009] A linear square pipeline modular detection robot based on a star-shaped tensegrity unit comprises: a plurality of three-bar star-shaped tensegrity unit modules with the same structure, wherein the plurality of three-bar star-shaped tensegrity unit modules are connected in series axially and rigidly through connection nodes to maintain collinearity;

[0010] Each of the three-bar star-shaped tensegrity unit modules comprises:

[0011] A central driving rod, both ends of which are rigidly connected to a connection node, namely a first connection node and a second connection node,

[0012] A first radial connecting plate is provided on the first connecting node;

[0013] 3 first radial cable units, one end of each of the three first radial cable units is connected to the first radial connecting plate, the other ends of the three first radial cable units are numbered as A, B, and C in clockwise order, and the end point of the central driving rod is O.

[0014] 3 second radial cable units, one end of each of the three second radial cable units is connected to the second radial connecting plate respectively,

[0015] The other ends of the three second radial cable units are numbered as D, E, and F in clockwise order, and the end point of the central driving rod is O'.

[0016] Three inclined cable units are connected between the AD endpoints, the BE endpoints, and the CF endpoints.

[0017] 3 straight rod units, connecting the AE endpoints, BF endpoints and CD endpoints respectively.

[0018] In the initial state, the three endpoints A, B, and C form an equilateral triangle ABC, O is the center of the equilateral triangle ABC, and the three endpoints D, E, and F form an equilateral triangle DEF, O' is the center of the equilateral triangle DEF;

[0019] Equilateral triangle ABC and equilateral triangle DEF are equal in size but are offset 30° from each other;

[0020] The plane defined by the three endpoints ABC is parallel to the plane defined by the three endpoints DEF;

[0021] The OO' line is horizontal, the CD line is horizontal, the A and F end points are in contact with the bottom surface of the pipeline, and the C and D end points are close to the two side walls of the pipeline;

[0022] The oblique cable units and radial cable units are both prestressed cables;

[0023] The central driving rod unit includes a fixed rod and a telescopic rod, and the relative movement between the telescopic rod and the fixed rod is adjusted by an actuator to change the length of the central driving rod unit;

[0024] Each three-rod star-shaped tensegrity unit has the performance of folding and unfolding, and the structural deformation is realized by the extension and contraction of the central driving rod.

[0025] The robot movement is achieved by controlling the length change of the center rod in sequence according to the principle of longitudinal wave method.

[0026] Furthermore, the oblique cable unit comprises:

[0027] 1 spring, located in the middle of the inclined cable unit;

[0028] Two sections of first rope are respectively connected to the two ends of the spring, and the other end of the first rope is connected to a fixing ring arranged at the end of the rod unit through a first spring hook; the spring is kept in a tensioned state, so that the inclined cable unit has prestress.

[0029] Furthermore, the radial cable unit comprises:

[0030] A second rope, one end of which is connected to the circular hole on the radial connecting plate through a second spring hook, and the other end of which is connected to the fixing ring at the end of the rod unit through a third spring hook.

[0031] Furthermore, the radial connecting plate is provided with a connecting outer tube, and the end of the central driving rod is provided with a connecting inner tube inserted into the connecting outer tube. After the connecting inner tube and the connecting outer tube are inserted, they are fixed by a connecting pin.

[0032] The present invention further discloses a walking method of the linear square pipeline modular detection robot based on the star-shaped tensegrity unit,

[0033] In each three-bar star-shaped tensegrity unit, one of the straight bar units is parallel to the bottom surface of the pipeline, and in each three-bar star-shaped tensegrity unit, two end points of the straight bar units are in contact with the bottom surface of the pipeline;

[0034] In the longitudinal wave method, the first three-bar star tensegrity unit is stretched first, stretched to the maximum and then begins to shorten, and each subsequent three-bar star tensegrity unit stretches while the previous three-bar star tensegrity unit shortens;

[0035] When the last three-bar star-shaped tensegrity unit is shortened, a longitudinal wave is transmitted in the robot, and the robot moves forward a certain distance;

[0036] The single longitudinal wave method is to transmit only one wave in the robot, and the multi-longitudinal wave method is to transmit multiple waves in the robot at the same time to speed up the movement efficiency.

[0037] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0038] First, from the perspective of control method, compared with most tensegrity robots with a large number of actuators, complex control schemes, and high control accuracy requirements, the present invention only needs to control the length change of the central driving rod, and the control strategy is easy to implement. The remaining rods and cables are passively changed, and the control method is simple and reliable.

[0039] Second, from the perspective of robot morphology, compared with ordinary pipeline robots that are heavy and bulky, the robot of the present invention is only composed of rods and cables, is light in weight, occupies a small cross-sectional area of ​​the pipeline, and will not block the pipeline when working.

[0040] Third, the robot designed by the present invention has strong modularity in assembly. The tensegrity unit adopts the same three-rod star-shaped tensegrity unit, which can be assembled from a plurality of the same oblique cable units, straight rod units, radial cable units, and central drive rod units. It can be assembled on site and is convenient to use.

[0041] In summary, the tensegrity pipeline detection robot has a simple control method, does not block the pipeline when crawling through the pipeline, is lightweight and efficient, has strong impact resistance, and has strong modular assembly, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Hide one side of the pipeline wall for the axonometric view of the linear square pipeline detection modular robot based on the star-shaped tensegrity unit of the present invention in the initial state;

[0043] Figure 2 A front view of the linear square pipeline detection modular robot based on the star-shaped tensegrity unit of the present invention in the initial state hides one side of the pipeline wall;

[0044] Figure 3 It is a side view of the linear square pipeline detection modular robot based on the star-shaped tensegrity unit of the present invention in the initial state;

[0045] Figure 4 It is a top view of the linear square pipeline detection modular robot based on the star-shaped tensegrity unit of the present invention in the initial state;

[0046] Figure 5 It is an axonometric view of a three-bar star-shaped tensegrity unit module of the present invention;

[0047] Figure 6 is a schematic diagram of an oblique cable unit of the present invention;

[0048] Figure 7 is a schematic diagram of a straight rod unit of the present invention;

[0049] Figure 8is a schematic diagram of a radial cable unit of the present invention;

[0050] Fig. 9 is a schematic diagram of a central driving rod unit of the present invention;

[0051] Fig.10 It is a front view of the connection node and the latch of the present invention;

[0052] Fig.11 is an axonometric view of the connection node and the latch of the present invention;

[0053] Fig.12 This is a schematic diagram of a connection node before connection of the present invention;

[0054] Fig.13 A schematic diagram of a connection node after connection of the present invention;

[0055] Fig.14 It is a schematic diagram of the connection between the spring hook in the cable module and the fixing ring in the straight rod unit of the present invention;

[0056] Fig.15 It is a schematic diagram of the deformation of the central driving rod of the three-rod star-shaped tensegrity of the present invention during one-time elongation and shortening;

[0057] Fig.16 This is a schematic diagram of the single longitudinal wave method movement gait of the present invention;

[0058] Fig.17 It is a schematic diagram of the movement gait of the multi-longitudinal wave method of the present invention;

[0059] Fig.18 This is a schematic diagram of the single longitudinal wave motion when n=5 in the robot embodiment 1 of the present invention;

[0060] Among them, 1 is a three-rod star-shaped tensegrity unit module, 2 is a connection node between the tensegrity unit modules, 201 is a node, 202 is a pin, 203 is a circular hole, 204 is a pin hole, 3 is a pipe, 4 is an inclined cable unit, 401 is a first rope, 402 is a spring, 403 is a first spring hook, 5 is a straight rod unit, 501 is a straight rod, 502 is a fixing ring on the rod, 6 is a radial cable unit, 601 is a second rope, 602 is a second spring hook, 603 is a third spring hook, 7 is a central driving rod unit, 701 is a fixed rod, 702 is a telescopic rod, and 703 is a pin hole. DETAILED DESCRIPTION

[0061] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding components and features.

[0062] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0063] Combine the following Figure 1-18 The illustrated linear square pipe detection modular robot based on star-shaped tensegrity units further describes the specific embodiments of the present invention.

[0064] like Figure 1-4 As shown, a schematic diagram of the tensegrity pipeline detection robot of the present invention is shown. Each tensegrity unit is connected by a connection node 2, and both ends of the connection node 2 are installed at the end points of the central rod 7 of each tensegrity unit, so that the connection mode of the central driving rods of adjacent units is rigid connection and remains collinear. When connected, each tensegrity unit has a rod parallel to the bottom surface of the pipeline, and each unit has two rod end points in contact with the lower bottom surface of the pipeline, and the two end points of the horizontal rod are as close to the side wall of the pipeline as possible. The six radial cables determine two parallel planes, and the planes are perpendicular to the forward direction of the robot. The central rod of the tensegrity unit is horizontal, each central rod is collinear, and the central rod is parallel to the forward direction of the robot.

[0065] like Figure 5 As shown, the assembly diagram of the tensegrity unit structure is shown, which includes three oblique cable units 4, three straight rod units 5, three radial cable units 6, and a central driving rod unit 7.

[0066] For the tensegrity unit nodes, the first three nodes are numbered A, B, and C in clockwise order, and the center rod endpoint is O; the last three nodes are numbered D, E, and F in clockwise order, and the center rod endpoint is O'. The three oblique cable units are connected to AD, BE, and CF, respectively; the three straight rod units are connected to AE, BF, and CD, respectively; the six radial cable units are connected to AO, BO, CO, DO', EO', and FO', respectively; and the center driving rod unit is connected to OO'.

[0067] In the initial state, the three nodes A, B, and C form an equilateral triangle ABC, O is the center of the equilateral triangle ABC, and the three nodes D, E, and F form an equilateral triangle DEF, O' is the center of the equilateral triangle DEF.

[0068] Equilateral triangle ABC and equilateral triangle DEF are equal in size but are offset 30° from each other;

[0069] The plane determined by the ABC three nodes is parallel to the plane determined by the DEF three nodes.

[0070] The OO' line is horizontal, the CD line is horizontal, the A and F nodes are in contact with the bottom surface of the pipeline, and the C and D nodes are close to the two side walls of the pipeline.

[0071] like Figure 6 As shown, the inclined cable unit is composed of two sections of first ropes 401, a spring 402, and two first spring hooks 403. The spring is located between the two sections of the first ropes. After the robot is assembled, the spring needs to be kept in a tensioned state so that the inclined cable unit has prestress.

[0072] like Figure 7 As shown, the straight rod unit is composed of a straight rod 501 and two fixing rings 502.

[0073] like Figure 8 As shown, the radial cable unit is composed of a second rope 601 , a first spring hook 602 and a second spring hook 603 .

[0074] like Fig. 9 As shown, the central driving rod unit is composed of a fixed rod 701, a telescopic rod 702, and two pin holes 703. The central driving rod unit needs to be equipped with an actuator to adjust the relative movement of the telescopic rod and the fixed rod to change the length of the central driving rod unit.

[0075] like Fig.10 , 11 As shown, the connection node is composed of a node 201 and two latches 202. Six circular holes 203 are opened on the node, and the circular holes are used to connect the spring hooks in the six radial cable units of two adjacent units.

[0076] Due to the geometric relationship of the tensegrity unit, the angular intervals of the six circular holes are 90°, 30°, 90°, 30°, 90°, and 30° respectively.

[0077] Two pin holes 204 are formed on the node to connect the central driving rod units of two adjacent units.

[0078] like Fig.12 , 13 As shown, when the nodes are connected, the pin holes 703 at both ends of the central driving rod need to be aligned with the pin holes 204 on the nodes, and then the pins 202 are inserted to achieve the rigid connection of the central driving rods of the adjacent units. The spring hooks in the radial cable units are connected to the circular holes 203 of the nodes to achieve the hinged connection between the radial cable units and the central straight rod units.

[0079] like Fig.14 As shown, the spring hooks in the oblique cable unit and the radial cable unit need to be connected to the fixing rings of the straight rod unit accordingly, and two spring hooks are connected to each fixing ring.

[0080] like Fig.15 As shown, each three-rod tensegrity unit has folding and unfolding properties, and structural deformation can be achieved by extending and retracting the central driving rod.

[0081] like Fig.16 , 17 As shown in the figure, in the longitudinal wave method, the first unit stretches first, and then begins to shorten after stretching to the longest length. Each subsequent unit stretches while the previous unit shortens. When the last unit shortens, a longitudinal wave is transmitted in the robot, and the robot moves forward a certain distance. The single longitudinal wave method is that only one wave is transmitted in the robot, and the multi-longitudinal wave method is that multiple waves are transmitted in the robot at the same time, which can speed up the movement efficiency.

[0082] Embodiment 1:

[0083] like Fig.18 As shown, the number of tensegrity unit modules n=5 is selected as the specific composition of the robot to demonstrate its forward movement process under a single longitudinal wave motion gait.

[0084] The above embodiments are only preferred implementation modes of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and equivalent substitutions without departing from the principles of the present invention. These technical solutions after improvements and equivalent substitutions to the claims of the present invention all fall within the protection scope of the present invention.

Claims

1. A modular detection robot for straight square pipes based on star-shaped tensegrity units, characterized in that: include: A plurality of three-bar star-shaped tensegrity unit modules having the same structure, wherein the plurality of three-bar star-shaped tensegrity unit modules are axially rigidly connected in series through connection nodes to maintain collinearity; Each of the three-bar star-shaped tensegrity unit modules comprises: A central driving rod unit, both ends of which are rigidly connected to a connection node, namely a first connection node and a second connection node, and the first connection node is provided with a first radial connection plate; 3 first radial cable units, one end of each of the three first radial cable units is connected to the first radial connecting plate, the other ends of the three first radial cable units are numbered as A, B, and C in clockwise order, and the end point of the central driving rod unit is O. 3 second radial cable units, one end of each of the three second radial cable units is connected to a second radial connecting plate respectively, The other ends of the three second radial cable units are numbered as D, E, and F in clockwise order, and the end point of the central driving rod unit is O'. Three inclined cable units are connected between the AD endpoints, the BE endpoints, and the CF endpoints. 3 straight rod units, respectively connecting the endpoints AE, BF and CD. In the initial state, the three endpoints A, B and C form an equilateral triangle ABC, O is the center of the equilateral triangle ABC, and the three endpoints D, E and F form an equilateral triangle DEF, O' is the center of the equilateral triangle DEF; Equilateral triangle ABC and equilateral triangle DEF are equal in size but are offset 30° from each other; The plane defined by the three endpoints ABC is parallel to the plane defined by the three endpoints DEF; The OO' line is horizontal, the CD line is horizontal, the A and F end points are in contact with the bottom surface of the pipeline, and the C and D end points are close to the two side walls of the pipeline; The oblique cable unit, the first radial cable unit and the second radial cable unit are all prestressed cables; The central driving rod unit includes a fixed rod and a telescopic rod, and the relative movement between the telescopic rod and the fixed rod is adjusted by an actuator to change the length of the central driving rod unit; Each three-rod star-shaped tensegrity unit has the performance of folding and unfolding. The structural deformation is achieved by the extension and retraction of the central driving rod unit. The robot movement is achieved by controlling the length change of the central rod in sequence according to the principle of longitudinal wave method.

2. The linear square pipeline modular detection robot based on star-shaped tensegrity unit according to claim 1 is characterized in that: The inclined cable unit comprises: 1 spring, located in the middle of the inclined cable unit; Two sections of first ropes are respectively connected to the two ends of the spring, and the other end of the first rope is connected to a fixing ring arranged at the end of the straight rod unit through a first spring hook; the spring is kept in a tensioned state, so that the inclined cable unit has prestress.

3. The linear square pipeline modular detection robot based on star-shaped tensegrity unit according to claim 1, characterized in that: The radial cable unit consists of: A second rope, one end of which is connected to the circular hole on the radial connecting plate through a second spring hook, and the other end of which is connected to the fixing ring at the end of the straight rod unit through a third spring hook.

4. The linear square pipeline modular detection robot based on star-shaped tensegrity unit according to claim 1, characterized in that: A connecting outer tube is arranged on the radial connecting plate, and a connecting inner tube inserted into the connecting outer tube is arranged at the end of the central driving rod unit. After the connecting inner tube and the connecting outer tube are inserted, they are fixed by a connecting pin.

5. A walking method of a linear square pipeline modular detection robot based on a star-shaped tensegrity unit according to any one of claims 1 to 4, characterized in that: In each three-bar star-shaped tensegrity unit, one of the straight bar units is parallel to the bottom surface of the pipeline, and in each three-bar star-shaped tensegrity unit, two end points of the straight bar units are in contact with the bottom surface of the pipeline; In the longitudinal wave method, the first three-bar star tensegrity unit is stretched first, stretched to the maximum and then begins to shorten, and each subsequent three-bar star tensegrity unit stretches while the previous three-bar star tensegrity unit shortens; When the last three-bar star-shaped tensegrity unit is shortened, a longitudinal wave is transmitted in the robot, and the robot moves forward a certain distance; The single longitudinal wave method is to transmit only one wave in the robot, and the multi-longitudinal wave method is to transmit multiple waves in the robot at the same time to speed up the movement efficiency.

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