A gun barrel defect detection pipe robot

Abstract

A kind of artillery barrel defect detection robot, including cleaning module, drive module and defect detection module, the drive module is the structure of variable diameter helical drive, its front end is connected the cleaning module, rear end is connected defect detection module, drive module movement brings cleaning module and defect detection module synchronous movement, it can carry out defect detection to the wear degree of artillery barrel internal rifling and barrel straightness, while robot carries cleaning brush, can simultaneously clean artillery barrel internal rifling, remove gunpowder residue, water vapor and other pollutants.

Description

Technical Field

[0001] This utility model belongs to the field of pipeline robot technology, specifically relating to a pipeline robot for detecting defects in artillery barrels. Background Technology

[0002] During firing, the combustion of ammunition generates high-temperature, high-pressure gases. These gases expand rapidly within the barrel, propelling the projectile at high speed. The barrel is subjected to alternating high-temperature and high-pressure environments over extended periods, enduring intense mechanical and thermal stresses, making it prone to structural damage such as cracks, wear, and corrosion. Furthermore, after firing, the inner wall of the barrel often accumulates contaminants such as gunpowder residue and moisture. These defects and impurities not only affect the artillery's firing accuracy and combat performance but can also potentially lead to safety accidents in extreme situations. Therefore, to ensure the structural integrity and operational reliability of the artillery, regular defect inspection and cleaning of the barrel are necessary. Utility Model Content

[0003] In response to the above-mentioned technological status, this utility model designs a pipeline robot for detecting defects in artillery barrels. It can detect the wear degree of the rifling inside the artillery barrel and the straightness of the barrel. At the same time, the robot carries a cleaning brush, which can simultaneously clean the rifling inside the artillery barrel to remove contaminants such as gunpowder residue and water vapor.

[0004] The technical solution adopted by this utility model is as follows: a pipeline robot for detecting defects in artillery barrels, including a cleaning module, a drive module and a defect detection module. The drive module is a variable-diameter spiral drive structure, with its front end connected to the cleaning module and its rear end connected to the defect detection module. When the drive module moves, it drives the cleaning module and the defect detection module to move synchronously.

[0005] The cleaning module includes a cleaning part and a driving part. The cleaning part includes a brush mounting plate, on which multiple brush holders are hinged and evenly distributed around the circumference. Each brush holder is equipped with a tension spring and a cleaning brush. One end of the tension spring is connected to the brush mounting plate and the other end is connected to the brush holder. The tension spring maintains the tendency of the brush holder to rotate radially outward. The front end of the brush holder is fixed with the cleaning brush.

[0006] The drive unit includes a motor mounting bracket and a DC motor. The DC motor is installed inside the motor mounting bracket, and its output shaft extends forward and is connected to the brush mounting plate through a coupling to drive the cleaning module to rotate. The motor mounting bracket is fixedly connected to the drive module.

[0007] The defect detection module is equipped with a laser displacement sensor and a PSD position sensor via a PSD position sensor mounting bracket.

[0008] Specifically, the defect detection module includes a defect detection part and a rotating part. The rotating part includes a motor mounting bracket and a stepper motor installed inside the motor mounting bracket. The defect detection part includes a PSD position sensor mounting bracket. A PSD position sensor is mounted at the front end of the PSD position sensor mounting bracket. A laser displacement sensor is mounted inside the PSD position sensor mounting bracket and extends from one side. The rear end of the PSD position sensor mounting bracket is connected to the output shaft of the stepper motor via a coupling, and the defect detection part is driven to rotate by the stepper motor.

[0009] The drive module can adopt the existing drive mechanism of an adaptive variable diameter pipeline robot. This invention also features an independently designed and improved drive module to accommodate the installation of the cleaning module and the defect detection module. The drive module includes a central variable diameter mechanism and three tracked leg modules evenly distributed around the outer periphery of the central variable diameter mechanism. The central variable diameter mechanism includes a central support and multiple support rods extending from the central support to both sides. A side end cap is fixedly installed at each of the left and right ends of the support rods. A left-moving slider and a right-moving slider are slidably fitted onto each support rod between the central support and the side end caps. Each tracked leg module is supported by at least two linkage mechanisms symmetrically arranged on both sides of the central support. Each linkage mechanism includes a long link and a short link. One end of the long link is hinged to the side of the left or right moving slider, and the other end is hinged to the tracked leg module. One end of the short link is hinged to the central support, and the other end is hinged to the middle section of the long link.

[0010] A left-hand screw is provided on the left movable slider, and a right-hand screw is provided on the right movable slider. The left-hand screw and the right-hand screw are threaded through the left movable slider and the right movable slider, respectively. A left limiting plate is installed on the outer end of the left-hand screw, and a right limiting plate is installed on the outer end of the right-hand screw. A return spring is sleeved on the left-hand screw between the left limiting plate and the left movable slider, and a return spring is also sleeved on the right-hand screw between the right limiting plate and the right movable slider.

[0011] A central double-head motor is installed inside the central support. The left-hand lead screw and the right-hand lead screw are respectively connected to the output shaft on one side of the central double-head motor through a coupling. The central double-head motor drives the left and right moving sliders to move closer or further apart synchronously.

[0012] The track foot module includes an active synchronous wheel assembly and a driven synchronous wheel assembly assembled from a central support rod, and a track mounted on the active synchronous wheel assembly and the driven synchronous wheel assembly; the central support rod includes a first central support rod and a second central support rod, and the active synchronous wheel assembly and the driven synchronous wheel assembly are respectively clamped and mounted on the two ends of the first central support rod and the second central support rod through a first mounting plate and a second mounting plate;

[0013] The active synchronizing gear set includes a first synchronizing gear and a second synchronizing gear rotatably mounted between a first mounting plate and a second mounting plate via a second drive shaft. The active synchronizing gear set is also rotatably mounted at the end of a central support rod via a first drive shaft. A large bevel gear is fixedly mounted on the outer end of the first drive shaft, and a small cylindrical gear is fixedly mounted on the first drive shaft between the first synchronizing gear and the second synchronizing gear. A large cylindrical gear is provided on the side of the first synchronizing gear, and the small cylindrical gear meshes with the large cylindrical gear for transmission. A drive motor is fixedly mounted on the central support rod, and the drive shaft of the drive motor is fixedly mounted with a small bevel gear that meshes with the large bevel gear, thereby realizing power transmission in the right-angle direction.

[0014] The driven synchronous pulley set includes a third synchronous pulley and a fourth synchronous pulley that are rotatably mounted between another set of first and second mounting plates via a shaft. The third synchronous pulley and the fourth synchronous pulley are driven by a track. The entire driven synchronous pulley set is also rotatably mounted at the other end of the central support rod via a shaft.

[0015] Furthermore, on one side of the central support rod, an arc-shaped limiting groove is provided for each of the active and driven synchronous wheel sets. The mounting axes of the two adjacent synchronous wheels of the active and driven synchronous wheel sets extend outward to form limiting pins. Each limiting pin extends into an arc-shaped limiting groove, and the center of the arc of the two limiting grooves coincides with the rotation axis of the synchronous wheel corresponding to the limiting pin inside. The limiting pin can be a spring bar with high rigidity attached to one end of the mounting shaft of the corresponding synchronous wheel, or a buffer spring can be provided at both ends of the arc-shaped limiting groove. When the limiting pin slides to one end in the arc-shaped limiting groove, the buffer spring provides flexible buffering to avoid collision and reduce the contact stress between the robot and the pipe wall. The arc angle of the arc-shaped limiting groove preferably spans 30°, and it spans 15° above and below the central axis of the central support rod. An electromagnetic brake is also provided between the driven synchronous wheel set and the central support rod.

[0016] Furthermore, a front camera module is mounted on the side of the motor mounting bracket of the cleaning module; a rear camera module is mounted on the side of the PSD position sensor mounting bracket of the defect detection module.

[0017] Furthermore, a cleaning module mounting part is fixedly connected to the front end of the center diameter changing mechanism. The cleaning module mounting part is fixedly connected to the side end cover at the axial front end via a connecting rod. A defect detection module mounting part is fixedly connected to the rear end of the center diameter changing mechanism. The defect detection module mounting part is fixedly connected to the side end cover at the axial rear end via multiple connecting rods. The cleaning module mounting part is used to fix the motor mounting bracket, and the defect detection module mounting part is used to fix the motor mounting bracket.

[0018] The robot is suitable for artillery barrels with an inner diameter ranging from 140 mm to 210 mm. The extension and retraction of the barrel diameter adaptation module ensures continuous contact between the tracked legs and the barrel wall, adapting to variable-diameter sections and maintaining the robot's stability and reliability within the barrel. Based on the aforementioned artillery barrel defect detection robot, the specific detection method is as follows:

[0019] S1: Conduct a comprehensive check on the power supply status, communication status, and acquisition accuracy of the laser displacement sensor and PSD position sensor to ensure that each sensor is in normal working condition and meets the data acquisition accuracy requirements;

[0020] S2: The defect detection module is driven forward inside the gun barrel by the pipeline robot. Before detection, the coaxiality is adjusted to make the measuring axis of the laser displacement sensor consistent with the axis of the gun barrel.

[0021] S3: Set the data acquisition parameters on the PC, including the rotation angle of the stepper motor, the axial step distance, the starting angle of the laser sensor, and establish a communication connection with the sensor to enter the data acquisition state;

[0022] S4: Start the rotation control program. Trigger a data acquisition event once every set rotation angle. Record the laser displacement data and PSD displacement data at the current angle position and upload the data to the computer in real time to complete the acquisition of 360°.

[0023] S5: After completing one round of data acquisition, control the robot to advance the preset step length along the barrel axis, and then perform another round of rotation acquisition operation.

[0024] S6: Repeat step S5 to complete the full-length coverage inspection of the artillery barrel;

[0025] S7: The collected laser displacement data is processed by the coordinate transformation matrix and converted into three-dimensional point cloud data in the artillery barrel base coordinate system;

[0026] S8: The RANSAC algorithm is used to remove noise points and outliers in the point cloud data. The least squares method is used to fit the cross-sectional profile of the retained data to calculate the rifling diameter. The calculated data is compared with the gun barrel design data to determine whether there is wear exceeding the limit.

[0027] S9: Using the center axis of the PSD position sensor target surface as a reference baseline, based on the offset of the center positions of multiple cross sections and the data recorded by the PSD position sensor, fit the axis offset curve of the gun barrel. Compare the maximum offset difference of the fitted axis offset curve with the predetermined error threshold to determine whether the straightness of the gun barrel meets the standard.

[0028] In step S3 above, the starting angle of the laser sensor is set to 0°; in step S4, a data acquisition event is triggered every 1.8° rotation.

[0029] In step S9 above, the offset of the center positions of multiple cross-sections is calculated using the formula... Perform calculations. x is the offset of the center point of the cross section. i and y i Here are the displacement data of the center point of the cross section, where The maximum value is the maximum offset difference.

[0030] The beneficial effects of this utility model compared to the prior art are as follows:

[0031] (1) This utility model provides a pipeline robot for detecting defects in artillery barrels. The central diameter-changing module is a composite diameter-changing structure composed of a screw-nut mechanism driven by a central dual-axis motor and a spring slider, which has the adjustment capability of combining active and passive diameter changing. When dealing with artillery barrels of different calibers and local diameter changes, this structure can not only achieve precise adjustment over a wide range, but also provide flexible buffering through the spring slider to reduce the contact stress between the robot and the pipe wall, effectively improving the robot's adaptability and operational stability in complex pipe diameter environments.

[0032] (2) A multi-source fusion defect detection system consisting of a laser displacement sensor and a PSD position sensor was constructed. The laser sensor is used to acquire the radial contour information of the gun rifling section, and the PSD sensor is used to measure the center offset of the detection device during axial movement, thereby evaluating the barrel straightness deviation. This system can simultaneously perform comprehensive detection of the gun barrel rifling wear and overall straightness status, effectively improving the integrity, intelligence, and reliability of the detection system. Attached Figure Description

[0033] The present invention will now be described in further detail with reference to the accompanying drawings:

[0034] Figure 1 This is a schematic diagram of the overall structure of the pipeline robot of this utility model;

[0035] Figure 2This is a schematic diagram of the working state of the pipeline robot of this utility model inside the artillery barrel pipeline;

[0036] Figure 3 This is a schematic diagram of the minimum radius tube structure of the pipeline robot drive module of this utility model;

[0037] Figure 4 This is a schematic diagram of the maximum radius tube structure of the pipeline robot drive module of this utility model;

[0038] Figure 5 This is a structural schematic diagram of the tracked leg module;

[0039] Figure 6 This is a schematic diagram of the central diameter changing mechanism;

[0040] Figure 7 This is a structural diagram of the cleanup module;

[0041] Figure 8 This is a structural diagram of the defect detection module;

[0042] Figure 9 This is a schematic diagram illustrating the working principle of the defect detection module;

[0043] Figure 10 This is a flowchart illustrating the working principle of the pipeline robot defect detection system of this utility model.

[0044] Among them, 1 is the cleaning module, 2 is the driving module, 3 is the defect detection module, and 4 is the gun barrel;

[0045] 11 is the cleaning part, 12 is the rotating part, 21 is the central diameter changing mechanism, 22 is the track leg module, 23 is the central connecting rod, and 31 is the defect detection part;

[0046] 111 is a tension spring, 112 is a brush holder, 113 is a cleaning brush, 114 is a locking screw, 115 is a brush mounting plate, 121 is a motor mounting bracket, 122 is a DC motor, 123 is a front camera module, 124 is a support component, 125 is a motor mounting retaining ring, and 126 is a plum blossom coupling.

[0047] 211 is a short connecting rod, 212 is a long connecting rod, 213 is a left limiting plate, 214 is a side end cover, 215 is a positioning nut, 216 is a left-hand screw, 217 is a support rod, 218 is a left-moving slider, 219 is a left LYCA plum blossom coupling, 2110 is a central double-headed motor, 2111 is a central support, 2112 is a return spring, 2113 is a right-hand screw, 2114 is a connecting rod, 2115 is a right limiting plate, 2116 is a right-moving slider, and 2117 is a right LYCA plum blossom coupling;

[0048] 221 is the active synchronous wheel assembly, 222 is the driven synchronous wheel assembly, 223 is the central support rod, and 224 is the track.

[0049] 2211 is a drive motor, 2212 is a small bevel gear, 2213 is a first drive shaft, 2214 is a large bevel gear, 2215 is a second drive shaft, 2216 is a small cylindrical gear, 2217 is a large cylindrical gear, 2218 is a first synchronous pulley, 2219 is a second synchronous pulley, 2221 is a third synchronous pulley, 2222 is a fourth synchronous pulley, 2223 is an electromagnetic brake, 2224 is a first mounting plate, 2225 is a limiting pin, 2226 is a second mounting plate, 2231 is a first central support rod, 2232 is a second central support rod, and 2233 is an arc-shaped limiting groove;

[0050] 311 is a PSD position sensor, 312 is a laser displacement sensor, 313 is a rear camera module, 314 is a positioning screw, 315 is a PSD position sensor mounting bracket, 321 is a motor mounting plate, 322 is a motor mounting bracket, 323 is a motor mounting bolt, 324 is a stepper motor, and 325 is a flange coupling. Detailed Implementation

[0051] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, this utility model will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it. The technical solution of this utility model will be described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0052] like Figure 1 As shown in Figure 10, this utility model provides a robot for defects in artillery barrels. The robot includes a cleaning module 1, a drive module 2, and a defect detection module 3. The front end of the drive module 2 is connected to the cleaning module 1 through a motor mounting bracket 121, and the rear end is connected to the defect detection module 3 through a motor mounting bracket 322.

[0053] The cleaning module 1 includes a cleaning section and a driving section. The cleaning section comprises a tension spring 111, a brush holder 112, a cleaning brush 113, a locking screw 114, and a brush mounting plate 115. Three brush holders 112 are hinged and evenly distributed around the brush mounting plate 115. Each brush holder 112 is equipped with a tension spring 111 and a cleaning brush 113. One end of the tension spring 111 is connected to the brush mounting plate 115, and the other end is connected to the brush holder 112. The tension force maintains the radial outward rotation tendency of the brush holder 112. The cleaning brush 113 is fixed to the end of the brush holder 112 and secured to the brush holder 112 by the locking screw 114. Utilizing the elastic properties of the tension spring 111, automatic adjustment and adaptation of the cleaning brush in axial position and radial cleaning range can be achieved, improving cleaning efficiency and fit. The drive unit includes a motor mounting bracket 121, a DC motor 122, a front camera module 123, a motor mounting retaining ring 125, and a perforated coupling 126. The DC motor 122 is mounted inside the motor mounting bracket 121 and fixedly positioned by the motor mounting retaining ring 125, which is located on the axial front end face of the motor mounting bracket 121. The perforated coupling 126 is mounted on the motor mounting retaining ring 125; one end of the perforated coupling 126 is connected to the output shaft of the DC motor 122, and the other end is connected to the central shaft of the brush mounting disc 115. When the DC motor 122 is energized, it drives the perforated coupling 126 to rotate, thereby driving the brush mounting disc 115 and its brush assembly to achieve a rotating cleaning function. The front camera module 123 is mounted on the outer periphery of the motor mounting bracket 121 and fixedly supported by a support member 124. In the illustrated embodiment, three are evenly distributed and used to observe the internal condition of the cleaned artillery barrel.

[0054] The drive module 2 uses a central variable diameter mechanism 21 as its core structure, which is connected to three track leg modules 22 evenly distributed on the periphery. Each track leg module 22 is equipped with an independent drive motor 2211, whose output shaft transmits torque through a bevel gear pair to drive the first synchronous wheel 2218 to rotate, thereby driving the track 224 to move and providing forward power for the robot body, achieving stable drive control and good pipeline adaptability.

[0055] The defect detection module 3 includes a defect detection part 31 and a rotating part 32. The defect detection part 31 includes a laser displacement sensor 312 and a PSD position sensor 311. The laser displacement sensor 312 is installed inside the PSD position sensor mounting bracket 315 and fixed by a positioning screw 314. The PSD position sensor 311 is located at the front end of the PSD position sensor mounting bracket 315, and a rear camera module 313 is also provided on the side of the PSD position sensor mounting bracket 315. The rotating part includes a motor mounting bracket 322 and a motor mounting plate 321. The motor mounting plate 321 is fixedly installed at the end of the motor mounting bracket 322 by motor mounting bolts 323. A stepper motor 324 is fixedly installed inside the motor mounting bracket 322, and the output shaft of the stepper motor 324 is connected to the PSD position sensor mounting bracket 315 through a flange coupling 325.

[0056] The central variable diameter mechanism 21 is based on a lead screw and nut mechanism and is hinged by three sets of linkage mechanisms to achieve synchronous driving of the track foot module 22. Specifically, the central variable diameter mechanism 21 includes a central support 2111 and support rods 217 extending from the central support 2111 to both sides. In the illustrated embodiment, the support rods 217 include three circumferentially distributed rods, and a side end cover 214 is fixedly installed at each of the left and right ends of the support rods 217. The side end cover 214 is fixed to the support rod 217 by a positioning nut 215. A left-moving slider 218 and a right-moving slider 2116 are respectively installed on both sides of the central support 2111 and mounted on the support rod 217. The linkage mechanism includes a short link 211 and a long link 212. One end of the long link 212 is hinged to the side of the moving slider, and the other end is hinged to the track foot module 22. One end of the short link 211 is hinged to the central support 2111, and the other end is hinged to the middle section of the long link 212. When the left and right moving sliders slide on the support rod 217, they drive the linkage mechanism to expand radially outward or contract radially, thereby causing the track foot module 22 to adapt to the inner diameter of the gun barrel. To ensure structural stability, as shown in the figure, the moving slider can be set as a triangular plate, with a linkage mechanism on each side of each edge, and two linkage mechanisms symmetrically arranged on each side relative to the central support 2111. That is, each track assembly module 22 is installed through four linkage mechanisms, and the four linkage mechanisms form a group. A left-hand lead screw 216 is provided on the left-moving slider 218, and a right-hand lead screw 2113 is provided on the right-moving slider 2116. The left-hand lead screw 216 and the right-hand lead screw 2113 are threaded through the left-moving slider 218 and the right-moving slider 2116, respectively. A left limiting plate 213 is installed on the outer end of the left-hand lead screw 216, and a right limiting plate 2115 is installed on the outer end of the right-hand lead screw 2113. A return spring 2112 is sleeved on the left-hand lead screw 216 between the left limiting plate 213 and the left-moving slider 218, and a return spring 2112 is sleeved on the right-hand lead screw 2113 between the right limiting plate 2115 and the right-moving slider 218. A return spring 2112 is also fitted between the sliders 2116. The left-hand lead screw 216 and the right-hand lead screw 2113 are respectively connected to the central double-head motor 2110 through the left LYCA plum blossom coupling 219 and the right LYCA plum blossom coupling 2117. When the central double-head motor 2110 starts, it drives the left-hand lead screw 216 and the right-hand lead screw 2113 to rotate, so that the left moving slider 218 and the right moving slider 2116 move closer or further apart synchronously, causing the radial outer end of the long connecting rod 212 to retract or expand outward, completing the synchronous radial extension and retraction of the track foot module 22, and realizing the diameter change action.

[0057] The front end of the central diameter changing mechanism 21 is fixedly connected to a cleaning module mounting part, which is fixedly connected to the side end cover 214 at the axial front end via a connecting rod. The rear end of the central diameter changing mechanism 21 is fixedly connected to a defect detection module mounting part, which is fixedly connected to the side end cover 214 at the axial rear end via multiple connecting rods 2114. The cleaning module mounting part is used to fix the motor mounting bracket 121, and the defect detection module mounting part is used to fix the motor mounting bracket 322.

[0058] There are three track foot modules 22, which are circumferentially distributed on the outer periphery of the central variable diameter mechanism 21 via three sets of linkage mechanisms. Each track foot module 22 includes a driving synchronous wheel set 221 and a driven synchronous wheel set 222 assembled by a central support rod 223, and a track 224 mounted on the driving synchronous wheel set 221 and the driven synchronous wheel set 222. The central support rod 223 includes a first central support rod 2231 and a second central support rod 2232. The driving synchronous wheel set 221 and the driven synchronous wheel set 222 are respectively clamped and mounted at the two ends of the first central support rod 2231 and the second central support rod 2232 via a first mounting plate 2224 and a second mounting plate 2226.

[0059] The active synchronizing gear set 221 includes a first synchronizing gear 2218 and a second synchronizing gear 2219 rotatably mounted between a first mounting plate 2224 and a second mounting plate 2226 via a second drive shaft 2215. The active synchronizing gear set 221 is also rotatably mounted at the end of a central support rod 223 via a first drive shaft 2213. A large bevel gear 2214 is fixedly mounted on the outer end of the first drive shaft 2213. A small cylindrical gear 2216 is fixedly mounted on the first drive shaft 2213 between the first synchronizing gear 2218 and the second synchronizing gear 2219. A large cylindrical gear 2217 is provided on the side of the first synchronizing gear 2218. The small cylindrical gear 2216 and the large cylindrical gear 2217 are meshed and driven together. A drive motor 2211 is fixedly mounted on the central support rod 223. The drive shaft of the drive motor 2211 is fixedly mounted with a small bevel gear 2212 that meshes with the large bevel gear 2214, realizing power transmission in the right-angle direction. Then, the torque is transmitted to the small cylindrical gear 2216 through the first transmission shaft 2213, and the small cylindrical gear 2216 meshes with the large cylindrical gear 2217 to rotate. The large cylindrical gear 2217 outputs power to the first synchronous pulley 2218 through the second transmission shaft 2215. The first synchronous pulley 2218 is connected to the second synchronous pulley 2219 through the track 224, realizing the synchronous movement of the active synchronous pulley set 221 and other pulley sets, thereby driving the entire track to operate in a coordinated manner.

[0060] The driven synchronous pulley set 222 includes a third synchronous pulley 2221 and a fourth synchronous pulley 2222, which are rotatably mounted between another set of first mounting plates 2224 and second mounting plates 2226 via a shaft. The third synchronous pulley 2221 and the fourth synchronous pulley 2222 are driven by a track 224. The entire driven synchronous pulley set 222 is also rotatably mounted at the other end of the central support rod 223 via a shaft. An electromagnetic brake 2223 is provided between the driven synchronous pulley set 222 and the central support rod 223.

[0061] On one side of the central support rod 223, preferably on the side without the drive motor 2211, in the illustrated embodiment, an arc-shaped limiting groove 2233 is provided on the first central support rod 2231 corresponding to the active synchronous pulley set 221 and the driven synchronous pulley set 222. The mounting axes of the second synchronous pulley 2219 and the third synchronous pulley 2221 extend outward to form limiting pins 2225. Each limiting pin 2225 extends into an arc-shaped limiting groove 2233, and the arc centers of the two arc-shaped limiting grooves 2233 coincide with the rotation axes of the second synchronous pulley 2219 and the third synchronous pulley 2221, respectively. The limiting pins 2225 inserted into the arc-shaped limiting grooves 2233 form an angle limiting mechanism. To improve safety redundancy, the limiting pins 2225 adopt an elastic rebound design, forming a buffer when they contact the edge of the limiting groove at the extreme position, allowing the driven synchronous pulley set 222 to swing smoothly within the range of -15° to 15°, effectively avoiding severe impact and structural fatigue.

[0062] See Figure 9 This is a schematic diagram illustrating the working principle of the defect detection module. It employs a laser triangulation-based ranging scheme. A laser sensor emits a laser beam onto the target surface. After the laser beam is reflected from the target surface, a photodetector receives the reflected light. A triangle is formed between the laser sensor, the target surface, and the photodetector. The distance between the target and the sensor can be calculated based on this geometric relationship. If the target object moves closer to or further away from the sensor, the position of the reflected light on the photodetector will shift accordingly. This method ensures efficient detection while avoiding unnecessary damage to the gun barrel.

[0063] In practical applications, the relative installation positions of the laser displacement sensor and the PSD position sensor can be adjusted to ensure that the rifling is within the effective measurement range of the sensors, thereby avoiding measurement errors caused by dead zones. The functional relationship between the measurement distance and the output signal of the photodetector can be clearly characterized by the following formula, which can further define the location of the dead zone and the effective measurement range of the system. Through precise system calibration and reasonable installation angle adjustment, the system's ability to identify rifling structures can be significantly improved, effectively eliminating the impact of measurement blind zones on detection accuracy and repeatability, and ensuring the stability and reliability of the system's measurement results.

[0064] Functional relationship between measured distance and photodetector output signal , where x is the distance being measured; x 1 represents the offset of the light spot on the PSD (calculated from the output signal); a The distance between the center point of the reference plane laser and the center point of the receiving lens; b The baseline distance (the fixed distance between the center point of the photodetector and the center of the receiving lens); The angle between the transmitting optical axis and the receiving optical axis (a key adjustable parameter).

[0065] A laser sensor is used to acquire distance data from the laser emitting surface to various points on the object's surface. This distance data reflects the spatial relationship between the object's surface and the sensor. Before the system operates, we need to calibrate the relative position and orientation between the laser sensor and the coupling. The initial position and orientation of the coupling are set as the reference coordinate system. Define the coupling coordinate system as The coordinate system of the laser sensor is Let the rotation angle of the stepper motor be... The distance the detection device travels during operation is The data is transformed into point cloud data in the base coordinate system through coordinate transformation. Finally, the required diameter data is obtained by fitting the point cloud data.

[0066] If conventional least squares methods are directly used for circle or diameter fitting, outliers can significantly interfere with the fitting results, causing the fitted diameter to be smaller or larger than the true value, thus misjudging the tube's state and leading to serious consequences. To address this issue, this implementation scheme adopts a strategy combining the RANSAC (Random Sample Consensus) algorithm with the least squares method as the basic approach for diameter fitting. The core idea is to leverage the powerful noise and outlier resistance of the RANSAC algorithm to select the set of "interior points" that best represent the true inner wall contour of the tube from the original data. Then, based on this pure set of interior points, the least squares method is used for high-precision diameter fitting. This method ensures both the robustness of the model and the accuracy of the final result.

[0067] The RANSAC algorithm and least squares method are used as the basic approach for diameter fitting. If the original dataset contains noise and outliers, directly using least squares fitting will result in significant bias due to outlier interference. In contrast, the RANSAC algorithm first randomly selects a small portion of the dataset to fit the initial model. Then, it measures the distance between all remaining data points and this model. If these distances are below a predefined threshold, they are marked as inliers. This process is repeated until the model with the most inliers is selected as the optimal model, thus avoiding the influence of outliers.

[0068] Define the basic model Set filtering criteria Tolerance threshold and number of iterations Filtering criteria Used to quickly eliminate erroneous models, tolerance threshold A balance needs to be struck between robustness and accuracy, and the number of iterations... The algorithm is then adjusted based on theoretical estimates and practical needs; the algorithm uses the minimum number of random samples. Fit the initial model and utilize the tolerance threshold. Filtering Consistent Sets Finally in In the next iteration, select the model with the most elements in the consistent set. As the optimal solution.

[0069] set up Intrapoint ratio: the ratio of the number of intrapoints to the number of data points in the dataset.

[0070] Assuming model fitting requires selection Let there be points, and set... Let be the probability of randomly selecting a point from the dataset as an interior point. This means that in a single random sample, The probability that all points are interior points. Correspondingly, express The probability that at least one of the points is an outlier (outlier) is such that the estimated model may be unreasonable.

[0071] set up Let the probability (i.e., the confidence level) be that the algorithm has at least one sampling point that is an interior point during the iteration process. This indicates that the algorithm never selected the desired option in all iterations. The probability that all points are interior points, according to probability theory:

[0072] Taking the logarithm of the above expression and rearranging it, we can obtain the number of iterations. It can be represented as:

[0073] In practical applications, the RANSAC algorithm is often used in combination with other methods. Using RANSAC to remove outliers and then applying least squares to fit the diameter of the filtered inliers can balance robustness and computational efficiency. Furthermore, RANSAC can be improved for different problems, such as through adaptive threshold settings and dynamic sampling strategies, to further enhance its performance.

[0074] In the process of high-precision detection of rifling diameter, it is important to note that the RANSAC algorithm itself has the characteristic of "single model fitting." Therefore, when dealing with data containing mixed negative and positive rifling, the original point cloud must first be classified. Specifically, based on the distinguishing features of negative and positive rifling in terms of diameter, the data to be processed is divided into two independent datasets, and circular model fitting is performed separately for each dataset. Taking circular fitting as an example, the RANSAC algorithm randomly selects three sampling points in each iteration to determine a hypothetical circular model (including the center coordinates and radius value). In each RANSAC iteration using circular fitting as an example, the algorithm randomly selects three sampling points. Based on geometric principles, these three points uniquely determine a hypothetical circular model M. This model M is essentially defined by the two parameters of the center coordinates and the radius. To improve the robustness and accuracy of the model, prior information is introduced in the early stage of fitting, and the radius value is initially screened using a preset screening condition k to eliminate models that deviate significantly from the actual structure. Subsequently, by substituting the model parameters into the calculation of the distance from the remaining sampling points to the center and comparing it with the tolerance threshold t, the set of interior points s that meets the accuracy requirements is selected. After repeating this process p times, the circle model with the largest number of inner points is selected as the best fitting result for the current dataset, thereby obtaining the diameter parameters corresponding to the negative and positive lines respectively.

[0075] This study first uses the RANSAC algorithm to preprocess the original data. Through model validation and iterative calculation, outlier data points deviating from the main distribution are removed. After the outlier removal is completed, the least squares method is used to calculate the diameter fit of the optimal model.

[0076] In rifling diameter testing, the diameter difference between the bore and basalt lines typically exceeds 3 mm. Based on this characteristic, the bore and basalt data are initially classified. Specifically, a reasonable radius threshold is set, with points of larger diameter classified as bore data and points of smaller diameter classified as basalt data.

[0077] The equation of a standard circle in a two-dimensional plane is shown below.

[0078] In the above formula Input point coordinates, Let the coordinates be the center of the circle. The radius is 3. The minimum point set required for the initial circle model in RANSAC is 3. The optimal point set obtained after processing by the RANSAC algorithm is... Since outlier interference has been eliminated, using the least squares method for fitting at this point can better guarantee its accuracy.

[0079] definition:

[0080] The above formula can be expressed as

[0081] Next, we will create a helper function:

[0082] Set of optimal points Substitute auxiliary function

[0083] when When it is the minimum value, For the parameters of the circle in question, differentiate with respect to G.

[0084]

[0085] Its extreme point is found to be:

[0086] in, They are respectively:

[0087] To improve the efficiency and accuracy of the RANSAC algorithm, several optimization methods can be employed. Tolerance threshold. t The threshold can be dynamically adjusted based on the characteristics of the data to avoid setting the threshold too low, resulting in too few interior points, or too high, introducing excessive noise. Number of iterations. p Unnecessary calculations can be reduced by adjusting the algorithm through theoretical calculations or based on the proportion of interior points found in each iteration. These optimization methods enable the RANSAC algorithm to better distinguish between bearish and bullish candlestick data, effectively eliminate noise interference, and provide more reliable support for data fitting.

[0088] in L 1 Using the reference axis as a reference, the tracked robot is equipped with displacement sensors to measure and record the distance between the center position of different sections and the reference axis. By calculating the section offset, it can be determined whether its straightness is up to standard.

[0089] After the experiment began, the central axis of the PSD target surface was used as a reference baseline. During the movement of the tracked robot inside the tube, the center point of each cross section was collected. P displacement data And calculate the cross-sectional offset at each point. This allows for the assessment of the straightness of the tube.

[0090] in, Calculation formula

[0091] According to the standard for straightness testing, this paper uses the maximum offset difference value. As an evaluation criterion, offset The value will be compared with a predetermined error threshold. If the value is lower than the predetermined error threshold, it indicates that the straightness of the tube meets the standard requirements; otherwise, it indicates that the straightness of the tube does not meet the standard requirements.

[0092] Figure 10 This is a flowchart illustrating the working principle of the pipeline robot defect detection system. The defect detection module includes a laser displacement sensor and a PSD position sensor. The robot moves along the axis of the artillery barrel. The laser displacement sensor collects displacement data of the rifling cross-section, while the PSD position sensor records the displacement data of the center point of the cross-section, used to detect straightness deviations in the barrel. After data acquisition, it is uploaded to a computer platform for analysis. First, the displacement data collected by the laser sensor is converted into three-dimensional point cloud data in base coordinates. Then, the RANSAC algorithm is used to eliminate outliers. Next, the least squares method is used to fit the data, calculate the diameter of the rifling, and evaluate whether it meets design requirements. Finally, combined with the PSD sensor data, the straightness of the barrel is detected to ensure that it meets standard requirements.

[0093] Before collecting data, the operating status of the laser sensor is first checked to ensure everything is functioning correctly. Then, the PC software is connected to the system to begin data acquisition, which involves several steps:

[0094] The first step is to set the initial position, place the detection device coaxially inside the gun barrel, and set the PC software so that the initial acquisition angle of the laser sensor is set to 0.

[0095] The second step is to set system parameters through PC software, including the forward and backward step lengths and the stepper motor rotation angle;

[0096] The third step, during data acquisition and transmission, involves the host computer issuing a start command, and the probe beginning to acquire data from its initial position. When rotating 1.8°, the probe records the geometric data of the current position until a complete 360° acquisition is completed. The data is then transmitted to the PC in real time and automatically saved.

[0097] Fourth, the system then repositions itself to 0° and begins the next round of data collection to ensure full coverage.

[0098] The fifth step involves repeatedly collecting and axially stepping data to finally complete the geometric data collection for the entire barrel.

[0099] The system offers flexible parameter settings, allowing adjustment of the rotation angle and step length according to actual working needs, thus adapting to inspection situations with varying sizes and precision requirements. Through cyclic data acquisition, it completely covers all areas of the tube's inner wall, ensuring the reliability and completeness of the inspection results.

[0100] The operation of this detection system mainly includes two key stages: sensor calibration and tube defect detection.

[0101] During the calibration process, the testing equipment moves along the inside of the pipeline under system control, simultaneously acquiring angle information and displacement data from the stepper motor, while the laser sensor collects distance data. This data is transmitted to the main control computer via a serial interface, where a particle swarm optimization algorithm is used to determine the spatial relationship between the laser sensor and the coupling center, and to calculate the corresponding coordinate transformation matrix.

[0102] In the defect detection stage, the system uses the previously obtained coordinate transformation matrix to convert the distance data collected by the laser sensor into spatial point cloud data in the base coordinate system. Data preprocessing and fitting are then performed to reconstruct the cross-sectional profile of the barrel rifling.

[0103] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A pipeline robot for detecting defects in artillery barrels, characterized in that, It includes a cleaning module, a driving module, and a defect detection module. The driving module is a variable-diameter spiral driving structure, with its front end connected to the cleaning module and its rear end connected to the defect detection module. The cleaning module includes a cleaning part and a driving part. The cleaning part includes a brush mounting plate, on which multiple brush holders are hinged and evenly distributed around the circumference. Each brush holder is equipped with a tension spring and a cleaning brush. One end of the tension spring is connected to the brush mounting plate and the other end is connected to the brush holder. The tension spring maintains the tendency of the brush holder to rotate radially outward. The front end of the brush holder is fixed with the cleaning brush. The drive unit includes a motor mounting bracket and a DC motor. The DC motor is installed inside the motor mounting bracket, and its output shaft extends forward and is connected to the brush mounting plate through a coupling to drive the cleaning module to rotate. The motor mounting bracket is fixedly connected to the drive module. The defect detection module is equipped with a laser displacement sensor and a PSD position sensor via a PSD position sensor mounting bracket.

2. The robot according to claim 1, characterized in that, The defect detection module includes a defect detection section and a rotating section. The rotating section includes a motor mounting bracket and a stepper motor installed inside the motor mounting bracket. The defect detection section includes a PSD position sensor mounting bracket. A PSD position sensor is mounted at the front end of the PSD position sensor mounting bracket. A laser displacement sensor is mounted inside the PSD position sensor mounting bracket and extends from one side. The rear end of the PSD position sensor mounting bracket is connected to the output shaft of the stepper motor via a coupling, and the defect detection section is driven to rotate by the stepper motor.

3. The robot according to claim 2, characterized in that, The drive module includes a central variable diameter mechanism and three track leg modules evenly distributed on the outer periphery of the central variable diameter mechanism. The central variable diameter mechanism includes a central support and multiple support rods extending from the central support to both sides. A side end cover is fixedly installed at each of the left and right ends of the support rods. A left moving slider and a right moving slider are slidably fitted on each support rod between the central support and the side end covers on both sides. Each track leg module is supported by at least two linkage mechanisms, which are symmetrically arranged on both sides of the central support. Each linkage mechanism includes a long link and a short link. One end of the long link is hinged to the side of the left or right moving slider, and the other end is hinged to the track leg module. One end of the short link is hinged to the central support, and the other end is hinged to the middle section of the long link. A left-hand screw is provided on the left movable slider, and a right-hand screw is provided on the right movable slider. The left-hand screw and the right-hand screw are threaded through the left movable slider and the right movable slider, respectively. A left limiting plate is installed on the outer end of the left-hand screw, and a right limiting plate is installed on the outer end of the right-hand screw. A return spring is sleeved on the left-hand screw between the left limiting plate and the left movable slider, and a return spring is also sleeved on the right-hand screw between the right limiting plate and the right movable slider. A central dual-head motor is installed inside the central support. The left-hand lead screw and the right-hand lead screw are respectively connected to the output shaft on one side of the central dual-head motor through a coupling. The central dual-head motor drives the left and right moving sliders to move closer or further apart synchronously.

4. The robot according to claim 3, characterized in that, The track foot module includes an active synchronous wheel assembly and a driven synchronous wheel assembly assembled from a central support rod, and a track mounted on the active synchronous wheel assembly and the driven synchronous wheel assembly; the central support rod includes a first central support rod and a second central support rod, and the active synchronous wheel assembly and the driven synchronous wheel assembly are respectively clamped and mounted on the two ends of the first central support rod and the second central support rod through a first mounting plate and a second mounting plate; The active synchronizing gear set includes a first synchronizing gear and a second synchronizing gear rotatably mounted between a first mounting plate and a second mounting plate via a second drive shaft. The active synchronizing gear set is also rotatably mounted at the end of a central support rod via a first drive shaft. A large bevel gear is fixedly mounted on the outer end of the first drive shaft, and a small cylindrical gear is fixedly mounted on the first drive shaft between the first synchronizing gear and the second synchronizing gear. A large cylindrical gear is provided on the side of the first synchronizing gear, and the small cylindrical gear meshes with the large cylindrical gear for transmission. A drive motor is fixedly mounted on the central support rod, and the drive shaft of the drive motor is fixedly mounted with a small bevel gear that meshes with the large bevel gear, thereby realizing power transmission in the right-angle direction. The driven synchronous pulley set includes a third synchronous pulley and a fourth synchronous pulley that are rotatably mounted between another set of first and second mounting plates via a shaft. The third synchronous pulley and the fourth synchronous pulley are driven by a track. The entire driven synchronous pulley set is also rotatably mounted at the other end of the central support rod via a shaft.

5. The robot according to claim 4, characterized in that, On one side of the central support rod, an arc-shaped limiting groove is provided for each of the active and driven synchronous pulley sets. The mounting axes of the two synchronous pulleys of the active and driven synchronous pulley sets that are close to each other extend outward to form limiting pins. Each of the two limiting pins extends into an arc-shaped limiting groove, and the arc center of the two arc-shaped limiting grooves coincides with the rotation axis of the synchronous pulley corresponding to the limiting pin inside.

6. The robot according to claim 5, characterized in that, An elastic buffer is provided between the two ends of the limiting pin and the arc-shaped limiting groove.

7. The robot according to claim 5, characterized in that, The arc angle span of the arc limiting groove is 30°, and it spans 15° above and below the central axis of the central support rod.

8. The robot according to claim 4 or 5, characterized in that, An electromagnetic brake is installed between the driven synchronous wheel assembly and the central support rod.

9. The robot according to claim 1, characterized in that, A front camera module is mounted on the side of the motor mounting bracket of the cleaning module; a rear camera module is mounted on the side of the PSD position sensor mounting bracket of the defect detection module.

10. The robot according to claim 3, characterized in that, The front end of the central diameter changing mechanism is fixedly connected to a cleaning module mounting part, which is fixedly connected to the side end cover at the axial front end via a connecting rod. The rear end of the central diameter changing mechanism is fixedly connected to a defect detection module mounting part, which is fixedly connected to the side end cover at the axial rear end via multiple connecting rods. The cleaning module mounting part is used to fix the motor mounting bracket, and the defect detection module mounting part is used to fix the motor mounting bracket.

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