Cable towed mobile inspection robot

Abstract

The application provides a moving detection robot in a submarine cable dragging process, which comprises a driving mechanism, a hydraulic system, a clamping mechanism, a submarine cable, a hydraulic cylinder, a walking mechanism and other components. The driving mechanism and the walking mechanism cooperate to realize the advancing and pose adjustment of the overall mechanism supporting device. The clamping mechanism controls the opening and closing of the clamping arm by the hydraulic cylinder, and the submarine cable is clamped when the center block reaches the upper end of the center block limiting shaft. When the submarine cable is deformed and stretched during the dragging process, the cross-sectional area of the key stress position of the submarine cable will become smaller. Since the micro-displacement sensor is arranged along the circumference of the submarine cable, the change amount can be accurately measured. When the change amount exceeds the set warning value, it indicates that the submarine cable is subjected to excessive stress, and the stretching and thinning cause mechanical damage. At this time, the robot issues an alarm to prevent the submarine cable from being broken due to excessive dragging force.

Description

Technical Field

[0001] This invention relates to a mobile inspection robot used during submarine cable towing, an inspection device for monitoring the condition of submarine cables during the underwater cable laying process, and specifically relates to underground pipeline laying technology based on horizontal directional drilling, particularly a clamping device for submarine cable inspection and maintenance equipment. It belongs to the field of marine equipment technology. Background Technology

[0002] In the Bohai Sea region of my country, the development of the Bohai Oilfield is ongoing. However, with the continuous development of extraction technology and platforms, the demand for electricity from oil well platforms is also increasing. After comprehensively comparing various power supply methods, transmitting electricity from the shore via cable is the most economical. However, the Bohai Sea area where shore power projects are implemented is densely populated with protected areas, shipping channels, and anchorages, which severely restricts the layout and laying of submarine cables. Therefore, horizontal directional drilling combined with cross-cutting is usually adopted. The horizontal directional drilling technology upon which long-distance submarine cable crossings are based is a construction technique for laying underground pipelines using a horizontal directional drilling rig without excavating the ground. The horizontal directional drilling rig can drill into the strata using a drill bit, and the guiding system on the drill bit controls the trajectory of the borehole, reaching the pipeline outlet according to the designed path. Then, the borehole is pulled back and enlarged, and multiple enlargements can be performed according to engineering requirements. The pipeline to be laid is then pulled through the borehole, and after the pipeline is in place, the cable is inserted, completing the cable laying task.

[0003] Therefore, when submarine cables are towed inside steel conduits, the frictional force between the cable and the inner wall of the conduit, spanning over 1000 meters, needs to be counteracted. At this point, the traction force applied during cable towing significantly exceeds the cable's maximum allowable tensile strength, causing mechanical damage, cracks, or even breakage. This situation is extremely dangerous, resulting in economic losses for oil and gas companies and increasing the environmental burden. The submarine cable mobile inspection robot designed in this invention will be used to inspect submarine cables inside pipelines during the towing process, issuing alarms for dangerous sections and protecting the cable from breakage. Summary of the Invention

[0004] The purpose of this invention is to disclose a mobile inspection robot used in the process of dragging submarine cables through conduits, which prevents the submarine cable from breaking due to excessive dragging force by detecting the radial deformation of the cable. It is suitable for situations where the maximum diameter of the submarine cable is between 252-300mm, the inner diameter of the steel conduit is 610mm, the water depth is 10-200m, and the dragging length is >1000m.

[0005] The objective of this invention is achieved as follows: It includes a clamping mechanism, a driving mechanism, and a traveling mechanism. The clamping mechanism comprises a central support rod, a central block limiting shaft located at the upper center of the central support rod, a central block located on the central block limiting shaft, two sliders hinged to both sides of the central block, a left clamping arm and a right clamping arm symmetrically hinged to the central support rod, a miniature hydraulic cylinder located between the left and right clamping arms, an upper arc plate located below the central support rod via an upper arc plate support shaft, and two side clamping arc plates located at the ends of the left and right clamping arms. Two pulleys are also connected to the sliding grooves of the left and right clamping arms. Outer clamping housings are respectively provided on both sides of the central support rod, a driving mechanism support seat is provided between the two outer clamping housings, a driving mechanism is provided above the driving mechanism support seat, and a traveling mechanism is provided on the outer clamping housings. Bullseye wheel support seats and sensor support seats are respectively provided on the upper arc plate and the two side arc plates, and a displacement sensor is provided on each sensor support seat.

[0006] The present invention also includes the following structural features:

[0007] 1. The traveling mechanism includes a traveling mechanism base fixedly connected to the outer clamping housing, two wheel welding blocks fixedly connected to the two traveling mechanism bases on both sides respectively, a universal wheel base plate fixedly connected to the wheel welding block by a base plate fixing nut and a support plate fixing bolt, a universal wheel support plate hinged to the universal wheel base plate, and a universal wheel hinged to the universal wheel support plate by a universal wheel pin shaft using a round nut and a universal wheel pin shaft.

[0008] 2. The drive mechanism includes a drive mechanism chassis mounted on a drive mechanism support, and the drive mechanism chassis can rotate around the central axis of the drive mechanism support. The steering motor is fixedly connected to the drive mechanism chassis, and its output end is connected to the driving pinion. The driving pinion and the driven gear mesh to drive the drive mechanism to achieve circumferential position adjustment. The driven gear is fixed on the drive mechanism support. The hydraulic motor is fixedly connected to the fixed base through hydraulic motor fixing bolts, and its output end is connected to the drive wheel to achieve the driving forward function.

[0009] Compared with existing technologies, the beneficial effects of this invention are as follows: Compared with existing optical inspection technologies for submarine cables inside pipelines, even with high precision requirements for the camera sensors used in optical inspection, the technology cannot accurately measure minute deformations of submarine cables due to environmental factors (water, sediment, etc.). Furthermore, the high cost due to limitations in data storage capacity and power consumption makes optical inspection technology unsuitable for inspecting submarine cables inside ultra-long pipelines. In contrast, the submarine cable mobile inspection robot uses a micro-displacement sensing detection method. The circumferentially arranged sensors achieve accurate measurement of submarine cable deformation, and the data transmission requirements are lower. The sensor information can be sent to a host computer outside the pipeline for observation or uploaded to a database for processing, achieving the technical advantages of low cost and high precision. Attached Figure Description

[0010] Figure 1 This is an isometric view of the moving detection robot during the submarine cable towing process;

[0011] Figure 2 This is the front view of the robot that detects movement during the towing of submarine cables;

[0012] Figure 3 This is a schematic diagram of the clamping mechanism in a mobile inspection robot during submarine cable towing. Figure 1 ;

[0013] Figure 4 This is a schematic diagram of the drive mechanism in the mobile inspection robot during submarine cable towing.

[0014] Figure 5 This is a schematic diagram of the clamping mechanism in a mobile inspection robot during submarine cable towing. Figure 2 ;

[0015] Figure 6 This is a cross-sectional view of the clamping mechanism in the moving detection robot during submarine cable towing;

[0016] Figure 7 This is a schematic diagram of the walking mechanism in the mobile detection robot during submarine cable towing.

[0017] Figure 8 This is a schematic diagram of the hydraulic circuit of a mobile inspection robot during submarine cable towing. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Combination Figures 1-8It mainly includes components such as a drive mechanism, hydraulic system, clamping mechanism, submarine cable, hydraulic cylinder, and traveling mechanism. The drive mechanism and traveling mechanism work together to enable the overall support device to move forward and adjust its position. The clamping mechanism is controlled by a hydraulic cylinder to open and close the clamping arm. When the center block reaches the upper end of the center block limit shaft, the submarine cable is clamped.

[0020] This invention comprises a walking mechanism 1, a walking mechanism base 2, two bullseye wheels 3, a sensor fixing nut 4, a sensor support fixing bolt 5, a sensor support 6, a sensor fixing bolt 7, an upper bullseye wheel 8, a clamping mechanism 9, a housing fixing bolt 10, a housing fixing component 11, an outer clamping housing 12, a support plate fixing bolt 13, a drive mechanism support bracket 14, a 125mm electro-hydraulic servo drive mechanism 15, an upper bullseye wheel support mounting bolt 16, an upper mounting bolt stop washer 17, an upper bullseye wheel support 18, a miniature hydraulic cylinder 19, a clamping mechanism middle fixing bolt 20, a hydraulic cylinder fixing nut 21, two bullseye wheel support brackets 30, two bullseye wheel support bracket mounting bolts 31, two mounting bolt stop washer 32, a KS8 micro-displacement sensor 33, and a submarine cable 34.

[0021] The clamping mechanism 7 mainly includes two clamping arc plates 35, an upper arc plate 36, a middle support rod 37, a clamping arm pin 38, a round nut for the clamping arm pin 39, a left clamping arm 40, an upper arc plate support shaft 41, a slider 42, a center block 43, a center block limiting shaft 44, and a right clamping arm 45.

[0022] The walking mechanism 1 mainly includes wheel welding block 22, base plate fixing nut 23, support plate fixing bolt 24, round nut for universal wheel pin 25, universal wheel support plate 26, universal wheel 27, universal wheel pin 28, and universal wheel base plate 29.

[0023] The drive mechanism 15 mainly includes a driving pinion 46, a drive mechanism chassis 47, a motor fixing bolt 48, a steering motor 49, a hydraulic motor 50, a hydraulic motor fixing bolt 51, a fixed base 52, a drive wheel 53, and a driven large gear 54.

[0024] The intermediate support rod 37 is a fixed component of the clamping mechanism. The center block limiting shaft 44 is fixedly connected to the upper center position of the intermediate support rod 37. The center block 43 slides on the center block limiting shaft 44. One end of the sliders 42 on both sides is hinged to the center block 43, and the other end is connected to the sliding groove of the left and right clamping arms. The left and right clamping arms are hinged to the intermediate support rod 37 by clamping arm pins 38 and round nuts 39. The two ends of the miniature hydraulic cylinder 19 are fixed by bolts in the middle of the clamping mechanism. The clamping arms 20 and 21 are hinged to the left clamping arm 40 and the right clamping arm 45 respectively, controlling the opening and closing of the clamping mechanism; the upper arc plate support shaft 41 is fixedly connected to the lower end of the middle support rod 37, and is symmetrically distributed along the axial direction of the coastal cable; the upper arc plate 36 is fixedly connected to the two upper arc plate support shafts 41; the two clamping arc plates 35 are fixed to the left clamping arm 40 and the right clamping arm 45 respectively, making them a whole, so as to better complete the clamping action.

[0025] The outer clamping housing 12 is fixedly connected to the intermediate support rod 37 by housing fixing bolts 10 and housing fixing parts 11; the drive mechanism support base 14 is fixedly connected to the outer clamping housing 12 by four support plate fixing bolts 13; the outer clamping housing 12 is fixedly connected to the walking mechanism base 2, and each side of the housing has two universal wheel installation positions and four walking mechanism bases, which are symmetrically arranged along the coastal cable axis; the two sides of the wheel welding block 22 are fixedly connected to the two walking mechanism bases 2 respectively, the universal wheel base plate 29 is fixedly connected to the wheel welding block 22 by base plate fixing nuts 23 and support plate fixing bolts 24, the universal wheel support plate 26 is hinged to the universal wheel base plate 29, and the universal wheel 27 is hinged to the universal wheel support plate 26 by universal wheel pins with round nuts 25 and universal wheel pins 28.

[0026] The upper bullseye wheel support 18 is fixedly connected to the upper arc plate 36 via the upper bullseye wheel support mounting bolt 16 and the upper mounting bolt stop washer 17, and is arranged back and forth along the axial direction to ensure that the upper side of the closely attached submarine cable is evenly stressed. The two bullseye wheel support seats 30 are fixedly connected to the two clamping arc plates 35 via the two bullseye wheel support seat mounting bolts 31 and the two mounting bolt stop washer 32, and are similarly arranged back and forth along the axial direction. The sensor support seat 6 is fixedly connected to the two clamping arc plates 35 via the sensor support seat fixing bolt 5. The KS8 micro-displacement sensor 33 is fixedly connected to the sensor support seat 6 via the sensor fixing nut 4 and the sensor fixing bolt 7, and is arranged on the front side of the mobile detection robot. Two sensors are distributed circumferentially on the upper and two clamping arc plates to facilitate the measurement of the small deformation of the submarine cable.

[0027] The drive mechanism chassis 47 is hinged to the drive mechanism support 14 and can rotate around the central axis of the drive mechanism support 14; the steering motor 49 is fixedly connected to the drive mechanism chassis 47 through the motor fixing bolt 48 and is located on one side. Its output end is connected to the driving pinion 46 and then meshes with the driven gear 54 to drive the drive mechanism to achieve circumferential position adjustment; the driven gear 54 is fixed on the drive mechanism support 14; the hydraulic motor 50 is fixedly connected to the fixed base 52 through the hydraulic motor fixing bolt 51, and its output end is connected to the drive wheel 53 to realize the driving forward function.

[0028] The hydraulic system uses YGX series miniature hydraulic cylinders - CA type hydraulic cylinders, supplied by an external umbilical cord. The clamping mechanism itself has a self-locking function. To ensure the reliability of gripping, a locking circuit can be designed for the hydraulic cylinder oil circuit. Dual hydraulic control check valves and three-position four-way directional valves are used together to vertically position the load. The drive system uses a 125mm electric hydraulic servo motor, which can achieve circumferential rotation and control the robot to adapt to different positions of the submarine cable in the pipeline. The electric motor controls the adjustment of posture, and the hydraulic motor drives the walking. The walking mechanism uses AX-40-S type rubber universal wheels, which can be used in conjunction with the drive system to achieve movement. The detection system uses a KS8 displacement sensor, which can determine the stress on the submarine cable by detecting changes in the cross-sectional diameter of the submarine cable at multiple points, and thus determine the towing conditions.

[0029] Working principle: The operation of the mobile inspection robot used during submarine cable towing consists of two steps: placing, positioning, and clamping the submarine cable, and moving and inspecting the cable, and adjusting its attitude. To address the uneven stress on the submarine cable during towing and to detect dangerous sections, the following operational plan is proposed:

[0030] (1) Placing and positioning the submarine cable: When electromagnet 1YA is energized, the pressure oil passes through the left position of the solenoid valve, through the speed regulating valve Q1, and enters the left chamber of hydraulic cylinder 19. The single piston rod hydraulic cylinder extends, causing the clamping arm to open significantly. The device is hoisted above the submarine cable 34 being pulled through the pipe and slowly lowered. After the bullseye wheel 8 at the upper arc plate is in close contact with the submarine cable, 1YA is de-energized and 2YA is energized. The pressure oil passes through the right position of the solenoid valve and enters the right chamber of hydraulic cylinder 19. The single piston rod hydraulic cylinder retracts, and the left clamping arm... When the right clamping arm 40 and the right clamping arm 45 close and grip, the center block 43 reaches the limit position of the center block limit shaft 44. Then, the electromagnets 1YA and 2YA are de-energized, the reversing valve is in the Y-type functional neutral position, and X1 and X2 form a bidirectional hydraulic control check valve. The hydraulic cylinder inlet and outlet oil circuits are closed. If there is no leakage in the hydraulic cylinder, the hydraulic circuit can be reliably positioned. The locking circuit ensures the long-term effectiveness of the clamping. At the same time, the bullseye wheels 3 at the clamping arc plates on both sides are also close to the submarine cable 34, completing the positioning and clamping of the device.

[0031] (2) Attitude adjustment and movement detection: The device is slowly pushed into the protective tube so that the rubber wheels of the 125mm electro-hydraulic steering mechanism 15 and the walking mechanism 1 are completely in contact with the protective tube. The attitude is automatically adjusted according to the relative position of the submarine cable 34 and the protective tube. Then, the forward and backward movement is completed by controlling the on and off of the electromagnets 3YA and 4YA. The flow rate of the oil inlet is adjusted by the one-way speed regulating valves Q2 and Q4. At the same time, the overall oil flow rate is kept constant by using the speed regulating valve Q3. After the support is stable, the relative position of the sensor 33 is adjusted to ensure that it is in full contact with the submarine cable and can work normally. During the process of dragging with the submarine cable, it is continuously moved and the stress of the submarine cable is detected to ensure that it will not be mechanically damaged.

[0032] Detection Principle: The KS8 micro-displacement sensor used by the robot operates on the potentiometer principle. Its built-in spring keeps the cable in constant contact with the cable surface, facilitating direct measurement of cable deformation and outputting a DC voltage signal. When the cable deforms and stretches during towing, the cross-sectional area of ​​the cable at critical stress points decreases. Because the micro-displacement sensor is circumferentially positioned along the cable, it can accurately measure the change. When the change exceeds a set warning value, it indicates excessive stress on the cable, causing it to thin and potentially break. At this point, the robot issues an alarm to prevent the cable from breaking due to excessive towing force.

[0033] This mobile inspection robot used during submarine cable towing is designed based on the actual needs of towing submarine cables within pipelines in my country, combined with the geological conditions of the Bohai Sea and shore power engineering technology, and meets the following design requirements:

[0034] 1) The device is used for submarine cable towing in conduits with a length >1000m, has automated inspection capabilities, and is easy to install and implement;

[0035] 2) The device is applicable to water depths of 10-200m;

[0036] 3) The device can handle the problem of dragging submarine cables of different sizes and specifications.

[0037] The mobile inspection robot used in submarine cable towing operations is mainly applied to submarine cable towing and inspection operations in nearshore waters with cable diameters of φ252-300mm, water depths of 10-200m, conduit diameters of 610mm, and cable towing lengths exceeding 1000m. In this embodiment, the submarine cable being gripped has a diameter of φ262mm, a total span length of 1000m, a permissible tensile force of 270.248kN, and is equipped with external armor and coated fabric.

[0038] The clamping mechanism's hydraulic cylinder has an inner diameter D = 20mm, a hydraulic rod diameter d = 10mm, a rated pressure of 7MPa, and a distance of 278mm between the two center holes. For example... Figures 1-3As shown, the design parameters of the structural support device are as follows: Specifications (length × width × height): 480 × 580 × 560 mm; Weight: 30 kg; Drive mechanism support base 5 steel plate thickness 10 mm; Center block 36 dimensions 40 × 40 × 20 mm; Diameter of the submarine cable 19 to be clamped 262 mm; Width of the intermediate support rod 30 40 mm; Plate thickness of the left clamping arm 33 and the right clamping arm 38 60 mm; Plate thickness of the upper arc plate 29 and the two side clamping arc plates 28 10 mm; Outer diameter of the outer clamping shell 4 D = 550 mm, wall thickness 10 mm; Bullseye wheels 22 at the two side clamping arc plates and bullseye wheels 27 at the upper arc plate are arranged at 90° intervals along the circumference, and KS8 micro-displacement sensor 18 is arranged similarly.

[0039] The mobile inspection robot used in submarine cable towing operations enables submarine cable towing and inspection operations with cable diameters of φ252-300mm and cable towing lengths exceeding 1000m. The clamping structure is highly adaptable to submarine cables and pipelines, while the high-sensitivity micro-power sensors enable real-time detection of cable stress and deformation to prevent mechanical damage. The drive mechanism and walking mechanism work together to adjust the robot's relative position to the cable within the pipeline, ensuring normal maneuverability and successful completion of inspection operations.

Claims

1. A mobile inspection robot during submarine cable towing, characterized in that: The system includes a clamping mechanism, a driving mechanism, and a traveling mechanism. The clamping mechanism includes a central support rod, a central block limiting shaft located at the upper center of the central support rod, a central block located on the central block limiting shaft, two sliders hinged to both sides of the central block, a left clamping arm and a right clamping arm symmetrically hinged to the central support rod, a miniature hydraulic cylinder located between the left and right clamping arms, an upper arc plate located below the central support rod via an upper arc plate support shaft, and two clamping arc plates located at the ends of the left and right clamping arms. Two pulleys are also connected to the sliding grooves of the left and right clamping arms. Outer clamping housings are located on both sides of the central support rod, a driving mechanism support seat is located between the two outer clamping housings, a driving mechanism is located above the driving mechanism support seat, a traveling mechanism is located on the outer clamping housings, and bullseye wheel support seats and sensor support seats are located on the upper arc plate and the two side arc plates, respectively. Each sensor support seat is equipped with a displacement sensor. In use, the cable is gripped tightly by closing the left and right clamping arms, and the displacement sensor is in close contact with the surface of the cable. When the cable deforms and stretches during towing, the cross-sectional area of ​​the cable at the key stress points will decrease. The displacement sensor is arranged circumferentially along the cable. When the change exceeds the set warning value, it indicates that the cable is under too much force. At this time, the robot issues an alarm to prevent the cable from breaking due to excessive towing force.

2. The mobile detection robot during submarine cable towing as described in claim 1, characterized in that: The traveling mechanism includes a traveling mechanism base fixedly connected to the outer clamping housing. The two sides of the wheel welding block are respectively fixedly connected to the two traveling mechanism bases. The universal wheel base plate is fixedly connected to the wheel welding block through the base plate fixing nut and the support plate fixing bolt. The universal wheel support plate is hinged to the universal wheel base plate. The universal wheel is hinged to the universal wheel support plate through the universal wheel pin shaft with a round nut and the universal wheel pin shaft.

3. The mobile detection robot during submarine cable towing as described in claim 1 or 2, characterized in that: The drive mechanism includes a drive mechanism chassis mounted on a drive mechanism support, and the drive mechanism chassis can rotate around the central axis of the drive mechanism support. The steering motor is fixedly connected to the drive mechanism chassis, and its output end is connected to the driving pinion. The driving pinion meshes with the driven gear, driving the drive mechanism to achieve circumferential position adjustment. The driven gear is fixed on the drive mechanism support. The hydraulic motor is fixedly connected to the fixed base through hydraulic motor fixing bolts, and its output end is connected to the drive wheel to achieve the driving forward function.

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