A composite motion mechanism of a pipeline robot and its control method

Abstract

This invention relates to the field of pipeline robot technology, specifically to a composite motion mechanism for a pipeline robot and its control method. The mechanism body includes an annular chamber assembly, a telescopic assembly, and two connecting assemblies. The annular chamber assembly is located in the middle and can contact and separate from the inner wall of the pipeline to achieve adaptive support motion. The telescopic assembly is axially wrapped by the annular chamber assembly and includes six pneumatic telescopic bodies and a central spring, enabling active steering and linear motion within the pipeline. The two connecting assemblies are located at both ends of the composite motion mechanism. The pipeline robot is assembled by connecting at least three composite motion mechanisms, enabling the robot to creep within the pipe. The composite motion mechanism of this invention enables the pipeline robot to actively steering and linearly move in small and medium-sized pipelines, provides high traction capacity, and exhibits strong adaptability and strong passage ability in pipelines with irregular inner walls.

Description

Technical fields:

[0001] This invention relates to the field of pipeline robot technology, and specifically to a composite motion mechanism for a pipeline robot and its control method. Technical background:

[0002] Pipelines are increasingly used in numerous fields, and pipeline robots, as a type of specialized robot, are seeing a growing number of applications for pipework. In actual pipeline systems, small and medium-sized pipelines often have unique configurations, such as T-shaped, L-shaped, obtuse, and acute angles, as well as a significant amount of horizontal and vertical pipe layout. Numerous pipeline robots have been developed to address these unique configurations. Young-Sik Kwon of Hanyang University in South Korea designed a foldable pipeline inspection robot capable of navigating vertical pipes and some bends; Chen Xiao of Wuhan University designed an adaptive tracked pipeline inspection robot with some ability to navigate bends and circular steps. However, existing pipeline robots are mostly rigid mechanisms and motor-driven, resulting in poor flexibility and insufficient traction, particularly in their ability to navigate complex pipelines.

[0003] With the emergence of new materials, various flexible pipeline robots have been developed, which, compared with rigid pipeline robots, have the advantages of better pipeline passage, higher flexibility, and stronger pipeline adaptability. However, most existing flexible pipeline robots have problems such as being unable to actively turn in special pipelines, insufficient traction force, and passive adaptation to pipelines, thus failing to meet practical needs. Summary of the Invention:

[0004] This invention addresses the technical problems of pipeline robots in small and medium-sized pipelines, such as the inability to actively turn, insufficient traction, and passive adaptation to pipeline conditions. It proposes a composite motion mechanism for pipeline robots and its control method. This invention enables pipeline robots to achieve turning and linear motion in special sections of small and medium-sized pipelines, provides high traction capacity, and exhibits strong active adaptability and high maneuverability in pipelines with irregular inner walls.

[0005] The specific technical solution is as follows:

[0006] This invention first provides a composite motion mechanism for a pipeline robot, characterized by comprising an annular chamber assembly, a telescopic assembly, and two connecting assemblies. The composite motion mechanism simultaneously possesses flexible support, active steering, and linear motion. It achieves radial expansion and contraction through the annular chamber assembly, completing contact and separation with the pipeline inner wall to realize flexible support. It achieves active steering at special pipeline locations through axial unilateral contraction and reset. It achieves linear motion by axial overall contraction and reset of the telescopic assembly, completing peristalsis within the pipe. The composite motion mechanism can be assembled into a pipeline robot using the connecting assemblies, enabling the connection of multiple composite motion mechanisms.

[0007] Preferably, the annular chamber assembly of the composite motion mechanism encloses the telescopic assembly, the annular chamber assembly and the telescopic assembly are coaxially fitted, the front and rear ends of the telescopic assembly are connected to the front and rear ends of the annular chamber assembly by threaded connection, and the connecting assembly is fixed to both ends of the composite motion mechanism by connecting screws to form a complete composite motion mechanism.

[0008] Preferably, the annular chamber assembly of the composite motion mechanism comprises a flexible support airbag, a sealing telescopic tube, a support airbag strip, front and rear support airbag end caps, a front sealing telescopic tube joint, a rear sealing telescopic tube joint, a front central spiral tube, and a rear central spiral tube, thereby achieving the flexible support function of the composite motion mechanism. The front support airbag end cap is a stepped annular groove structure, coaxially arranged on the front side of the flexible support airbag. The rear support airbag end cap is a stepped annular groove structure, coaxially arranged on the rear side of the flexible support airbag. The inner side of the flexible support airbag coaxially engages with the grooved surfaces of the front and rear support airbag end caps, and is sealed using raw material. The sealing telescopic tube is a trapezoidal corrugated tube structure, coaxially engaging with the minimum diameter outer circular curved surfaces of the front and rear sealing telescopic tube joints, and is sealed by adhesive bonding. The aforementioned front and rear sealing telescopic tube joints are stepped annular structures, including three outer circular curved surfaces with different diameters. The outer circular curved surface with the middle diameter is coaxially fitted with the inner rings of the front support airbag end cap and the rear support airbag end cap, and is sealed by adhesive bonding. It is fixed to the front and rear support airbag end caps by connecting screws. The front and rear central spiral tubes are annular structures, half of which has external threads along its axial length, and are connected to the threaded holes in the center of the inner side of the front and rear support airbag end caps.

[0009] Preferably, the axial inner end face of the front support airbag end cap has a circumferentially distributed hexagonal prism groove, and the center position of the bottom of the hexagonal prism groove has an air tube through hole that axially penetrates the front support airbag end cap.

[0010] Preferably, the axial inner surface of the rear support airbag end cap has circumferentially distributed cylindrical grooves, which do not axially penetrate the rear support airbag end cap. There are six hexagonal prism grooves and six cylindrical grooves, with an included angle of 60 degrees between any two adjacent grooves.

[0011] Preferably, the support airbag strip is arranged in the groove of the front and rear support airbag end caps to securely seal the flexible support airbag.

[0012] Preferably, the telescopic component of the composite motion mechanism comprises a through-plate air pipe connector, a front cover chuck, a pneumatic telescopic body, a spherical nut, a rear cover chuck, connecting screw holes, and a central spring, enabling active steering in special pipelines and linear motion within the pipeline. The through-plate air pipe connector has a central through hole, a pagoda-shaped nozzle structure on the left, a hexagonal prism structure in the middle, and a right-side externally threaded column structure passing through the air pipe connector through holes around the front cover chuck. The front cover chuck is a ring structure with circumferentially distributed air pipe connector through holes and screw through holes, which mate with the threaded holes of the front support airbag end cap. The pneumatic telescopic body is an elastic flexible cavity that can be axially contracted by driving gas. The front end of the pneumatic telescopic body is threadedly connected to the through-plate air pipe connector, and the rear end is connected to the spherical nut. The spherical nut has a spherical structure with a spherical head and a cylindrical body, which mates with the hinge through holes around the rear cover chuck. The rear end cover chuck has a circular structure with circumferentially distributed spherical nut through holes and screw through holes, which mate with the threaded holes of the rear support airbag end cover. The central spring can return to its original shape after contraction and extension. The central spring is arranged between the front and rear end cover chucks and is coaxially engaged with the central spiral tube.

[0013] Preferably, the telescopic assembly includes six through-plate air pipe connectors, six pneumatic telescopic bodies, six ball nuts, and a central spring. The through-plate air pipe connectors are circumferentially fixed to the front end cover chuck, with any two included angles being 60 degrees. The six pneumatic telescopic bodies are I-VI, and are circumferentially connected between the front and rear end cover chucks, with any two included angles being 60 degrees. The ball nuts are circumferentially connected to the rear end cover chuck, with any two included angles being 60 degrees.

[0014] Preferably, one side of the telescopic assembly is filled with driving gas, causing the pneumatic telescopic body to contract axially, thus completing the active bending of the steering drive assembly on one side and realizing the active steering of the composite motion mechanism. Alternatively, all the pneumatic telescopic bodies of the telescopic assembly are filled with driving gas, causing them to contract axially, thus completing the overall axial contraction of the telescopic assembly and realizing the linear motion of the composite motion mechanism.

[0015] Preferably, the pneumatic telescopic body and the central spring are in an antagonistic fit, wherein the antagonistic fit means that the axial contraction of the pneumatic telescopic body and the axial extension of the central spring always interact with each other, so that the telescopic assembly is always in an axially taut state.

[0016] Preferably, the connecting assembly consists of connecting brackets and connecting screws. A composite motion mechanism has two connecting brackets, which are fixed to both ends of the annular chamber assembly by connecting screws. The pipe robot is assembled by these brackets. The pipe robot requires at least three composite motion mechanisms to achieve movement inside the pipe. The connecting assembly enables the connection between the composite motion mechanisms.

[0017] Preferably, the basic components of the control method for the composite motion mechanism of the pipeline robot mainly consist of an air compressor, an air filter, a pressure reducing valve, an oil mist lubricator, a gas flow regulating valve, a valve seat, a three-position five-way solenoid valve, and several air pipes. There are seven three-position five-way solenoid valves, all of which are center-sealed three-position five-way solenoid directional valves: a first solenoid directional valve, a second solenoid directional valve, a third solenoid directional valve, a fourth solenoid directional valve, a fifth solenoid directional valve, a sixth solenoid directional valve, and a seventh solenoid directional valve. These solenoid directional valves are arranged side-by-side via valve seats. The first to sixth solenoid directional valves are sequentially connected to the air circuits of the first to sixth pneumatic telescopic bodies, and the seventh solenoid directional valve is connected to the air circuit of the annular chamber. Simultaneously, the left air outlets of the first to seventh solenoid directional valves are connected to the air circuit, while the right air outlets are completely blocked. The specific implementation steps are as follows:

[0018] 1) After connecting the main gas circuit, the pressure and flow rate of the driving gas are controlled by the pressure reducing valve and the gas flow regulating valve to meet the conditions.

[0019] 2) Open the seventh solenoid directional valve to the left position to connect with the main air circuit. The driving gas begins to enter the annular chamber assembly of the compound motion mechanism. The flexible support airbag begins to inflate. After the predetermined flexible support time is completed, open the seventh solenoid directional valve to the middle position. The flexible support airbag stops inflating and comes into close contact with the irregular pipe wall. The compound motion mechanism is in the flexible support holding state. Open the seventh solenoid directional valve to the right position. The driving gas begins to exit the annular chamber assembly of the compound motion mechanism. The flexible support airbag begins to contract and gradually separates from the irregular pipe wall. The compound motion mechanism returns to its original state.

[0020] 3) Open the first to third solenoid directional valves to the left position to connect with the main air circuit, and open the fourth to sixth solenoid directional valves to the middle position. The driving gas begins to enter the I, II, and III pneumatic telescopic bodies and begins to contract axially, while the IV, V, and VI pneumatic telescopic bodies remain unchanged. The compound motion mechanism begins to actively turn in the direction of the I, II, and III pneumatic telescopic bodies. After the turning is completed, close the first to third solenoid directional valves to the middle position. The driving gas no longer enters the I, II, and III pneumatic telescopic bodies and keeps them in axial contraction. The compound motion mechanism maintains its turning in the direction of the I, II, and III pneumatic telescopic bodies. Open the first to third solenoid directional valves to the right position. The driving gas begins to discharge the I, II, and III pneumatic telescopic bodies and restores them to their original state. The compound motion mechanism returns to its original state. The active turning control of the compound motion mechanism in other directions is based on the same principle.

[0021] 4) Open all six solenoid directional valves to the left position to connect with the main air circuit. The driving gas begins to enter the first to sixth pneumatic telescopic bodies and begins to contract axially, pulling the compound motion mechanism to contract axially as a whole. Open all six solenoid directional valves to the middle position. The driving gas no longer enters the first to sixth pneumatic telescopic bodies and keeps them in axial contraction. The compound motion mechanism remains in axial contraction. Open all six solenoid directional valves to the right position. The driving gas begins to exit the first to sixth pneumatic telescopic bodies and restores them to their original state. The compound motion mechanism returns to its original state. Based on this method, and by controlling at least three compound motion mechanisms, the linear motion of the pipeline robot in the pipeline can be realized.

[0022] The composite motion mechanism of the pipeline robot of the present invention has the following advantages:

[0023] 1. It can achieve active steering function. In special pipeline sections of small and medium-sized pipelines, based on the feedback signal from the sensor module installed on the head of the pipeline robot, the active steering of the composite motion mechanism is achieved by controlling the active bending of the telescopic component on one side of the axis, thus providing the pipeline robot with active steering capability in special pipeline sections.

[0024] 2. It can multiply the output traction force. This composite motion mechanism can be modularly assembled, and the number of active transformation mechanisms can be increased according to actual needs to achieve the purpose of multiplying the output traction force of the pipeline robot. The pipeline robot needs to include at least three composite motion mechanisms to achieve movement inside the pipe.

[0025] 3. It can achieve strong active adaptability within pipelines. The flexible support airbag of this composite motion mechanism has excellent environmental adaptability. Even in pipelines with irregular inner walls, it can still achieve active and tight contact with the pipe wall, providing strong support for the pipeline robot. At the same time, when the pipeline robot is used in operation with at least 4 composite motion mechanisms assembled together, if one of the active steering modules fails and cannot operate normally, the other 3 composite motion mechanisms can still be used to move within the pipe, giving the robot excellent active adaptability.

[0026] 4. It enables strong passage through pipes. The telescopic components of this composite motion mechanism have excellent steering capabilities, allowing for active obstacle avoidance within pipes with obstacles, thus providing the pipe robot with powerful passage capabilities.

[0027] 5. It can achieve closed-loop control. The head of the composite motion mechanism has a threaded hole for installing a sensor. The pipeline robot assembled from this mechanism can realize active steering at special pipelines and precise control of active obstacle avoidance inside the pipeline based on the signals fed back by the sensor, thereby maximizing the intelligence level of the pipeline robot. Attached image description:

[0028] Figure 1 This is a schematic diagram of the overall structure of the composite motion mechanism of the pipeline robot according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic cross-sectional view of the composite motion mechanism of the pipeline robot according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic structural view of the annular chamber assembly and connecting components of the mechanism.

[0031] Figure 4 This is a structural diagram of the telescopic component of the mechanism.

[0032] Figure 5 This is a schematic diagram of the active steering motion of the mechanism at a special pipeline.

[0033] Figure 6 This is a wiring diagram of the mechanism's control circuit.

[0034] The labels in the diagram represent: 1-Annular chamber assembly, 2-Telescopic assembly, 3-Connecting assembly, 11-Front support airbag end cap, 12-Flexible support airbag, 13-Rear support airbag end cap, 14-Front sealing telescopic tube connector, 15-Rear sealing telescopic tube connector, 16-Sealing telescopic tube, 17-Front central spiral tube, 18-Rear central spiral tube, 19-Support airbag strip, 110-Quick air hose connector, 111-Annular chamber assembly air inlet, 112-Cylindrical groove, 113-Hexagonal prism groove, 114-Pneumatic telescopic body air inlet, 115-Steering positioning slot, 21-Through-plate air hose connector, 22-Front end cap chuck. 23-Rear end cover chuck, 24-Center spring, 25-Spherical nut, 26-Pneumatic telescopic body, 261-Front pneumatic telescopic body plug, 262-Rear pneumatic telescopic body plug, 263-Pneumatic telescopic body strip, 264-Pneumatic telescopic body woven mesh, 265-Pneumatic telescopic body elastic element, 31-Connecting angle bracket, 32-Connecting screw. Detailed implementation method:

[0035] The following diagrams and specific implementation methods illustrate this organization in detail:

[0036] according to Figure 1-6 As shown, the composite motion mechanism of a pipeline robot disclosed in this invention mainly includes 1-annular chamber assembly, 2-telescopic assembly, and 3-connecting assembly. The annular chamber assembly 1 coaxially encloses the telescopic assembly 2 inside, and the two are connected by connecting screws. The connecting assembly 3 is fixed to both ends of the annular chamber assembly outside by connecting screws.

[0037] In this invention, the annular chamber assembly 1 comprises a front support airbag end cap 11, a flexible support airbag 12, a front support airbag end cap 13, a front sealing telescopic tube connector 14, a rear sealing telescopic tube connector 15, a sealing telescopic tube 16, a front central spiral tube 17, a rear central spiral tube 18, a support airbag strip 19, and a quick-connect air tube connector 13. The front support airbag end cap 11 and the front support airbag end cap 13 have an annular groove structure in the middle. Multiple layers of sealing PTFE tape are wrapped around the perimeter of the annular groove. The front and rear ends of the flexible support airbag 12 are fitted onto the annular grooves of the front and rear end caps. The support airbag strip 19 fixes the flexible support airbag 12 to the annular groove structure of the front and rear end caps and seals it. The two ends of the sealing telescopic tube 16 respectively mate with the smallest diameter annulus of the front and rear sealing telescopic tube connectors 15 and 16, and are glued and sealed. The front and rear sealing telescopic tube connectors 15 and 16 respectively mate with the outer inner rings of the front and rear support airbag end caps 11 and 13, are glued and sealed, and are fixed with screws. Both the front and rear central spiral tubes 17 and 18 are annular structures, with half of their axial length threaded to mate with the threaded holes at the center of the inner sides of the front and rear support airbag end caps 11 and 13. The driving gas enters or exits the annular chamber assembly through the annular chamber inlet 112 in the rear support airbag end cap, enabling the expansion and contraction of the flexible support airbag 12 and completing the support and recovery of the composite motion mechanism within the pipe.

[0038] In this invention, the telescopic assembly 2 comprises a through-plate air pipe connector 21, a front cover chuck 22, a rear cover chuck 23, a central spring 24, a ball nut 25, and pneumatic telescopic bodies 26. The front cover chuck 22 and the rear cover chuck 23 are arranged at both ends of the central spring 24. The central spring 24 is pre-compressed to a certain amount and is located at the axial center position. The telescopic assembly 2 has six pneumatic telescopic bodies 26, which are arranged circumferentially between the front and rear chucks 6 and 7 at 60-degree intervals, surrounding the central spring. The ball nuts 25 and the through-plate air pipe connector 21 are respectively connected to the front and rear ends of the pneumatic telescopic bodies 26, thereby forming the telescopic assembly.

[0039] In this invention, the annular chamber assembly 1 encloses the telescopic assembly 2. The cylindrical groove 112 on the inner periphery of the front support airbag end cap 11 engages with the ball nut 25. The hexagonal prism groove 113 on the inner periphery of the rear support airbag end cap 13 engages with the through-plate air pipe connector 21 and is glued and sealed. The inner rings of the front and rear end cap chucks 6 and 7 engage with the front and rear central spiral tubes 17 and 18. Then, the front end cap chuck 22 and the rear end cap chuck 23 are fixed to the front and rear support airbag end caps 11 and 13 respectively by connecting screws 32. Thus, the ball nut 25 is locked in the cylindrical groove 112, and the through-plate air pipe connector 21 is locked in the hexagonal prism groove 113. In this way, the annular chamber assembly 1 and the telescopic assembly 2 cooperate to form the middle main body of the composite motion mechanism.

[0040] In this invention, the connecting assembly consists of connecting brackets 31 and connecting screws 32. A composite motion mechanism has two connecting brackets 31, which are fixed to the outer ends of the annular chamber assembly by the connecting screws 32. The pipeline robot requires at least three composite motion mechanisms to achieve movement within the pipeline. The connecting assembly 3 enables the combination of these composite motion mechanisms, thus completing the assembly of the pipeline robot.

[0041] The working principle of this mechanism is explained in detail below:

[0042] The assembly of the pipeline robot can be completed by using at least three interconnected composite motion mechanisms, which simultaneously enable the pipeline robot to achieve flexible support, active steering, and linear motion inside the pipeline.

[0043] A flexible support command is issued via the PC, initiating the flow of gas into the annular chamber assembly 1 of the composite motion mechanism. The flexible support airbag 12 begins to inflate. After the predetermined flexible support time is completed, a maintain flexible support command is issued from the PC. Figure 5 As shown, the flexible support airbag 12 stops inflating and comes into close contact with the irregular tube wall. The composite motion mechanism is in a holding state of maintaining support. The PC end issues a command to stop the flexible support, and the driving gas begins to be discharged from the annular chamber assembly 1 of the composite motion mechanism. The flexible support airbag 12 begins to contract and gradually separates from the irregular tube wall. The composite motion mechanism returns to its original state.

[0044] Taking a T-shaped pipe as an example, the active steering motion of the compound motion mechanism can be achieved, such as... Figure 6 As shown, the composite motion mechanism is located in a complex pipeline and needs to be able to turn vertically into the pipeline. An active turning command is issued through the PC terminal, and driving gas is injected into the pneumatic telescopic body 26 on one side of the telescopic assembly 2. The pneumatic telescopic bodies 26-I, 26-II, and 26-III on one side begin to contract axially, while the pneumatic telescopic bodies 26 on the opposite side do not receive driving gas. The pneumatic telescopic bodies 26-IV, 26-V, and 26-VI on the opposite side remain unchanged, thereby pulling the composite motion mechanism to actively turn vertically into the pipeline.

[0045] Linear motion within the pipeline is achieved through a composite motion mechanism. The PC issues a start linear motion command, simultaneously injecting driving gas into the six pneumatic telescopic bodies 26 of the telescopic assembly. The pneumatic telescopic bodies 26 overcome the force of the central spring 24 and begin axial contraction, thus achieving overall axial contraction of the composite motion mechanism. After executing the linear motion command, the PC issues a maintain linear motion command, the pneumatic telescopic bodies 26 stop receiving driving gas and remain in a contracted state. The PC then issues a stop linear motion command, the driving gas begins to dissipate from the six pneumatic telescopic bodies 26, and the composite motion mechanism returns to its original state under the action of the central spring 24. Based on this method, linear motion within the pipeline robot can be achieved by coordinating and controlling at least three composite motion mechanisms.

[0046] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A composite motion mechanism for a pipeline robot, characterized in that: It includes an annular chamber assembly, a telescopic assembly, and two connecting assemblies; the annular chamber assembly is located in the middle of the compound motion mechanism, the telescopic assembly is axially wrapped by the annular chamber assembly, and the two connecting assemblies are located at both ends of the compound motion mechanism. The annular chamber assembly comprises a flexible support airbag, a sealing telescopic tube, a front support airbag end cap, a rear support airbag end cap, a support airbag strip, a front sealing telescopic tube connector, a rear sealing telescopic tube connector, a front central spiral tube, and a rear central spiral tube. The front and rear support airbag end caps are stepped annular groove structures, coaxially arranged at the front and rear ends of the flexible support airbag. The inner side of the flexible support airbag coaxially mates with the grooved surfaces of the front and rear support airbag end caps, sealed with raw material. The sealing telescopic tube is a trapezoidal corrugated tube structure, coaxially arranged at the front sealing telescopic tube connector. The middle of the head and rear sealing telescopic tube joint is sealed by adhesive bonding with the outer ring of the smallest diameter of the front and rear sealing telescopic tube joints; the front and rear sealing telescopic tube joints are stepped annular structures, with the outer ring of the middle diameter coaxially fitting with the inner ring of the front and rear support airbag end caps for sealing, and fixed to the front and rear support airbag end caps by connecting screws; the front and rear central spiral tubes are annular structures, which are connected to the threaded holes in the center of the inner side of the front and rear support airbag end caps. The telescopic component of the composite motion mechanism consists of a through-plate air pipe connector, a front cover chuck, a pneumatic telescopic body, a spherical nut, a rear cover chuck, a central spring, and connecting threaded holes. The through-plate air pipe connector has a pagoda-shaped nozzle structure and connects with the through-plate air pipe connector through holes distributed around the front cover chuck. The front cover chuck has a circular ring structure with through-plate air pipe connector through holes and screw through holes distributed around its perimeter, and connects with the threaded holes of the front support airbag end cap. The pneumatic telescopic body is an elastic flexible cavity, with its front end connecting with the external thread of the through-plate air pipe connector and its rear end connecting with the threaded hole of the spherical nut. The spherical nut has a spherical structure and connects with the spherical nut through holes distributed around the rear cover chuck. The rear cover chuck has a circular ring structure with through-plate air pipe connector through holes and screw through holes distributed around its perimeter, and connects with the threaded holes of the rear support airbag end cap. The central spring is arranged between the front cover chuck and the rear cover chuck and has a certain pre-compression amount. The telescopic assembly includes six through-plate air pipe connectors, six pneumatic telescopic bodies, six ball nuts, and a central spring. The through-plate air pipe connectors are circumferentially fixed to the front end cover chuck, with an angle of 60 degrees between any two adjacent through-plate air pipe connectors. The pneumatic telescopic bodies are circumferentially connected between the front end cover chuck and the rear end cover chuck, with an angle of 60 degrees between any two adjacent pneumatic telescopic bodies. The ball nuts are circumferentially connected to the rear end cover chuck, with an angle of 60 degrees between any two adjacent ball nuts.

2. The composite motion mechanism of a pipeline robot according to claim 1, characterized in that: The annular chamber assembly encloses the telescopic assembly. The cylindrical holes on the inner periphery of the front support airbag end cap mate with ball nuts, and the hexagonal prism grooves on the inner periphery of the rear support airbag end cap mate with the through-plate air pipe connector and are glued and sealed. The central through holes of the front cover chuck and the rear cover chuck mate with the front center spiral tube and the rear center spiral tube. The front cover chuck and the rear cover chuck are fixed to the front support airbag end cap and the rear support airbag end cap by connecting screws. Thus, the annular chamber assembly and the telescopic assembly constitute the main body of the composite motion mechanism.

3. The composite motion mechanism of a pipeline robot according to claim 1, characterized in that: The connecting assembly consists of connecting brackets and connecting screws. A composite motion mechanism has two connecting brackets, which are fixed to the two ends of the annular chamber assembly by connecting screws.

4. A control method for a composite motion mechanism of a pipeline robot according to any one of claims 1-3, characterized in that: 1) After connecting the main air circuit, open the seventh solenoid directional valve to the left position to connect with the main air circuit. The driving gas begins to enter the annular chamber assembly of the compound motion mechanism. The flexible support airbag begins to expand. After the flexible support is completed, open the seventh solenoid directional valve to the middle position. The flexible support airbag stops expanding and comes into close contact with the irregular pipe wall. The compound motion mechanism is in a state of maintaining support. Open the seventh solenoid directional valve to the right position. The driving gas begins to exit the annular chamber assembly of the compound motion mechanism. The flexible support airbag begins to contract and gradually separates from the irregular pipe wall. The compound motion mechanism returns to its original state. 2) Open the first to third solenoid directional valves to the left position to connect with the main air circuit, and open the fourth to sixth solenoid directional valves to the middle position. Drive gas enters pneumatic telescopic bodies I, II, and III and causes them to contract axially, while pneumatic telescopic bodies IV, V, and VI remain unchanged. Pneumatic telescopic bodies I, II, and III pull the compound motion mechanism to actively turn in the direction of pneumatic telescopic bodies I, II, and III. After the turning is completed, close the first to third solenoid directional valves to the middle position. Drive gas no longer enters pneumatic telescopic bodies I, II, and III and keeps them axially contracted. The compound motion mechanism remains turned in the direction of pneumatic telescopic bodies I, II, and III. Open the first to third solenoid directional valves to the right position. Drive gas begins to exit pneumatic telescopic bodies I, II, and III and causes them to return to their original axial length. The compound motion mechanism returns to its original state. The turning principle of the compound motion mechanism in other directions is the same. 3) Open all six solenoid directional valves to the left position to connect with the main air circuit, drive gas into pneumatic telescopic bodies I to VI and cause them to contract axially, pulling the compound motion mechanism to begin overall axial contraction. Open all six solenoid directional valves to the middle position, drive gas no longer enters pneumatic telescopic bodies I to VI and keeps them axially contracted. The compound motion mechanism remains in the axial contraction state. Open all six solenoid directional valves to the right position, drive gas begins to exit pneumatic telescopic bodies I to VI and causes them to return to their original axial length. The compound motion mechanism returns to its original state.

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