Tunnel air-wind pipe lapping robot

Abstract

The application discloses a tunnel air and water pipe lapping robot and belongs to the technical field of tunnel construction equipment. In view of the problems of low efficiency and poor precision of manual judgment of flange butt joint and visual alignment of bolt holes, the robot comprises a power assembly bin, a walking track assembly, a rack, a rotating disc, a mechanical arm main body, a snatch lifting part, a force sensor, an axial walking mechanism, a rotary driving mechanism, an infrared opposite emission sensor and a controller. The technical scheme points are as follows: the snatch lifting part clamps the pipes, and then the mechanical arm main body is lifted to a preset height, so that the deflection angle and the radial offset of the two flanges reach the standard; the axial walking mechanism makes the two flange surfaces close to a preset interval; the rotary driving mechanism drives the snatch lifting part to rotate, and the infrared opposite emission sensor stops after detecting that the bolt holes are aligned; after the sensor is removed and confirmed, the axial walking mechanism continues to advance until the force sensor detects that the contact force reaches a first preset threshold value, and the clamping is maintained until the bolt connection is completed. The robot is mainly used for automatic lapping of tunnel air and water pipes, and efficiency and precision are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of tunnel construction equipment, and more specifically, this invention relates to a tunnel ventilation and water pipe splicing robot. Background Technology

[0002] In the construction of high-pressure ventilation and water pipe connections in tunnels, each pipe has flanges at both ends. Construction workers need to align the flanges of the pipe to be connected with those of the already installed pipes before inserting bolts to complete the connection. Due to the significant weight of a single pipe, the axial alignment of the flanges relies heavily on the experience of the workers during manual lifting and connection with tunnel machinery, which can easily lead to insufficient or excessive compression. Furthermore, aligning the bolt holes of the two flanges requires manual visual inspection and repeated rotation of the pipes for adjustment, a cumbersome process that makes it difficult to guarantee hole accuracy. These problems result in lengthy connection times per operation, and misalignment can cause difficulties in bolt insertion or uneven stress on the flanges. Current construction methods lack specialized equipment capable of automatically aligning flanges axially and accurately aligning bolt holes; relying solely on manual labor and general-purpose lifting machinery makes efficient and stable connection operations difficult. Summary of the Invention

[0003] One object of the present invention is to address at least the aforementioned deficiencies and to provide at least the advantages that will be described later.

[0004] This invention provides a tunnel ventilation and water pipe splicing robot, which can automatically complete the alignment of bolt holes and axial tightening judgment between the flange of the pipe to be spliced ​​and the flange of the installed pipe, reducing repeated manual adjustments and visual errors, and improving the efficiency and splicing accuracy of tunnel ventilation and water pipe splicing construction.

[0005] This invention provides a tunnel ventilation and water pipe splicing robot, comprising a powertrain compartment, a frame installed at the bottom of the powertrain compartment, a walking track assembly installed at the bottom of the frame, a rotating disk installed at the top of the frame, a three-joint robotic arm body installed on the rotating disk, a gripping part installed at the end of the robotic arm body for gripping the pipe to be spliced, a force sensor installed on the gripping part, an axial walking mechanism installed between the bottom of the rotating disk and the frame, a rotary drive mechanism installed between the gripping part and the end of the robotic arm body, an infrared beam sensor, and a controller. The controller is electrically connected to the walking track assembly, the rotating disk, the robotic arm body, the gripping part, the force sensor, the axial walking mechanism, and the rotary drive mechanism, and can also be electrically connected to the matching infrared beam sensor. The transmitting end of the infrared beam sensor can be installed in one of the bolt holes of the flange of the pipe to be spliced, and the receiving end of the infrared beam sensor can be installed in the bolt hole of the flange of the pipe already installed, corresponding to the bolt hole. The optical path between the transmitting end and the receiving end is along the axial direction of the bolt hole. After the gripping unit clamps the pipe to be docked, the controller drives the main body of the robotic arm to lift the pipe to be docked to a preset height, so that the axial deflection angle between the center axis of the flange of the pipe to be docked and the center axis of the flange of the installed pipe is within a preset angle range, and the radial offset is within a preset offset range. The controller drives the axial travel mechanism to move the flange face of the pipe to be connected axially toward the flange face of the installed pipe until the axial distance between the flange face of the pipe to be connected and the flange face of the installed pipe is reduced to within the preset spacing range. The controller then pauses the axial travel mechanism and enters the standby state. The controller drives the gripping part to rotate through the rotary drive mechanism. At the same time, the infrared beam sensor starts to detect. When the flange to be docked rotates until its bolt holes are aligned with the bolt holes of the installed flange, the infrared light emitted by the transmitter passes through the aligned bolt holes on the two flanges and is received by the receiver. The controller stops the rotation of the rotary drive mechanism according to the received signal. After the infrared beam sensor is manually removed, the controller automatically executes the hole alignment confirmation step. The hole alignment confirmation step is used to verify the bolt hole alignment status. After the confirmation is completed, a continue signal is sent to the controller by operating the confirmation button on the controller. After receiving the continue signal, the controller continues to drive the axial travel mechanism to move the flange face of the pipe to be connected axially toward the flange face of the installed pipe until the force sensor detects that the contact force between the flange face of the pipe to be connected and the flange face of the installed pipe reaches the first preset threshold. At this point, the controller causes the axial travel mechanism to pause and enter the standby state while maintaining the clamping state of the gripping part. The gripping part will release the clamping part after the operator sends a bolt connection completion signal to the controller via the completion button on the controller.

[0006] In tunnel ventilation and water pipe splicing construction, judging the axial alignment of flanges relies on manual experience, and bolt hole alignment depends on repeated manual visual adjustments, resulting in low efficiency and poor accuracy. To address this, this invention first uses an axial travel mechanism to bring the two flange faces close to a preset distance, avoiding frictional damage caused by rotation during contact. Then, an infrared beam sensor passes through the two aligned bolt holes to achieve automatic hole alignment. Finally, a force sensor detects the contact force on the flange faces as feedback for proper clamping, forming a step-by-step automated closed-loop control. This reduces repeated manual adjustments and visual errors, improves splicing efficiency and alignment accuracy, and prevents flange damage due to improper contact.

[0007] Preferably, the rotary drive mechanism includes a servo motor, a reducer, and a gear. The servo motor is installed at the end of the main body of the robotic arm and is connected to the gear through the reducer. An arc-shaped rack is provided on the gripping part, and the arc-shaped rack is arranged along the arc of the rotation direction of the gripping part. The gear meshes with the arc-shaped rack. An arc-shaped guide rail is fixed at the end of the main body of the robotic arm, and a slider that slides with the arc-shaped guide rail is fixed on the gripping part. The arc of the arc-shaped guide rail is the same as the arc of the arc-shaped rack, and their centers coincide with the rotation center of the gripping part. The gripping part includes a pair of grippers and a hydraulic cylinder that drives the pair of grippers to open and close. The hydraulic cylinder is electrically connected to the controller.

[0008] During the automatic flange alignment process, the rotary drive mechanism needs to rotate the gripping unit and the clamped pipe, while simultaneously bearing the off-center load torque caused by the weight of the pipe. To address this, this invention employs a servo motor that drives a gear via a reducer to mesh with an arc-shaped rack on the gripping unit. This, combined with an arc-shaped guide rail and slider, provides sliding guidance, allowing the rotational motion to proceed along a fixed arc trajectory. The gripping unit is then driven by a hydraulic cylinder to open and close a pair of jaws. This structure enables arc-shaped rotation within a limited space.

[0009] To withstand the eccentric torque generated by the weight of the gripping unit and the pipe it holds, an arc-shaped guide rail is fixedly installed at the end of the robotic arm's main body. A slider that slides along the arc-shaped guide rail is fixedly installed on the gripping unit. The curvature of the arc-shaped guide rail is the same as the curvature of the arc-shaped rack, and their centers coincide at the rotation center of the gripping unit. The arc-shaped guide rail is made of 45 steel profile with a rectangular cross-section, and precision raceways for matching balls are opened on both sides, with a surface hardening treatment. The slider that slides along the arc-shaped guide rail is fixed on the gripping unit, and the slider has balls embedded in it that fit against the raceways, forming a rolling guide pair. This combination of arc-shaped guide rail and slider not only bears the radial and axial loads generated by the weight of the gripping unit and the pipe, but also provides precise guidance for the rotational motion, preventing the gripping unit from swaying or shaking during rotation.

[0010] The gripping unit includes a pair of opposing grippers and a hydraulic cylinder for opening and closing the grippers. The two grippers are hinged to the base of the gripping unit, and the cylinder body of the hydraulic cylinder is hinged to the base. The piston rod of the hydraulic cylinder is connected to the two grippers via a linkage mechanism. When the hydraulic cylinder extends, the two grippers move towards each other to clamp the pipe; when the hydraulic cylinder retracts, the two grippers move away from each other to release the pipe. The hydraulic cylinder is electrically connected to a controller, which controls the opening and closing of the grippers by controlling the solenoid directional valve of the hydraulic cylinder.

[0011] Preferably, the rotary drive mechanism is further equipped with an angle encoder for real-time detection of the rotation angle of the gripping part; when the infrared beam sensor receives an infrared light signal, the controller records the angle value fed back by the angle encoder as the target angle; after the infrared beam sensor is manually removed and a continue signal is sent, the controller continues to drive the axial travel mechanism while maintaining the gripping part at the target angle (the target angle is the angle corrected and updated after the hole state confirmation step) through closed-loop control of the rotary drive mechanism according to the real-time feedback of the angle encoder, until the force sensor detects that the contact force reaches the first preset threshold.

[0012] The angle encoder can be an absolute rotary encoder or an incremental rotary encoder. Its installation method is as follows: the stator of the angle encoder is fixedly installed at the end of the robot arm body, and the rotor of the angle encoder is fixedly connected to the output shaft of the reducer. The rotation angle of the gripping part is indirectly obtained by detecting the rotation angle of the output shaft. The signal output terminal of the angle encoder is electrically connected to the signal input terminal of the controller. The controller obtains the real-time rotation angle value of the gripping part by reading the pulse signal or digital signal of the angle encoder.

[0013] After the infrared through-beam sensor completes automatic alignment, it needs to be manually removed. However, during the subsequent axial clamping process, the pipe to be connected may rotate unexpectedly due to vibration or gaps, causing misalignment of the aligned bolt holes. To address this, this invention adds an angle encoder to the rotary drive mechanism. When the infrared signal is triggered, the current angle is recorded as the target angle. While the sensor is removed and axial movement continues, the controller uses real-time feedback from the angle encoder to maintain the gripping unit at the target angle in a closed-loop control. In this way, even without infrared feedback, the circumferential phase of the flange bolt holes remains unchanged, preventing bolt hole misalignment during clamping, ensuring smooth bolt insertion, and reducing the need for secondary manual adjustments.

[0014] Preferably, the controller drives the robotic arm to lift the pipe to be docked to a preset height, so that the axial deflection angle between the center axis of the flange of the pipe to be docked and the center axis of the flange of the installed pipe is within a preset angle range and the radial offset is within a preset offset range. The specific implementation method is as follows: The frame is equipped with a binocular vision camera, and the axial walking mechanism has a built-in position sensor to detect the axial movement distance of the rotating disk relative to the frame. The controller stores the position and attitude data of the installed pipe flange in the robot's base coordinate system, as well as the fixed axial offset of the pipe flange surface to be docked relative to the coordinate system of the end of the robotic arm under the gripping state of the gripping part. After the gripper grasps the pipe to be docked, the controller controls the binocular vision camera to acquire images of the flange of the pipe to be docked. A stereo matching algorithm is used to calculate the 3D position and spatial orientation of the flange in the binocular vision camera coordinate system. The controller then transforms the 3D position and spatial orientation of the flange to be docked into the robot's base coordinate system based on the calibration transformation matrix between the binocular vision camera coordinate system and the robot's base coordinate system. The controller compares the position and orientation data of the flange to be docked with that of the already installed flange, calculating the axial deflection angle deviation and radial offset deviation between the two flange center axes. Based on the calculated deviations, the controller uses inverse kinematics to obtain the motion compensation amounts for each joint of the robotic arm, driving the robotic arm to move so that the axial deflection angle between the center axis of the flange to be docked and the center axis of the already installed flange are within a preset angle range and the radial offset is within a preset offset range. After the axial deflection angle and radial offset are adjusted, the controller measures the initial axial distance D0 between the flange face of the pipe to be docked and the flange face of the installed pipe again through a binocular vision camera. The controller drives the axial travel mechanism to move the flange face of the pipe to be docked axially toward the flange face of the installed pipe, and at the same time reads the axial movement distance S in real time according to the position sensor built into the axial travel mechanism. The controller calculates the current axial distance D = D0 - S. When D shrinks to within the preset spacing range, the controller makes the axial travel mechanism pause and enter the standby state.

[0015] Preferably, after the axial travel mechanism pauses and enters standby mode while maintaining the gripping state of the gripping part, during the manual tightening of the bolts, the controller continuously receives real-time feedback from the angle encoder; when the absolute value of the deviation between the actual rotation angle of the gripping part and the target angle exceeds a preset deviation threshold, the controller applies a compensating torque in the opposite direction through the rotation drive mechanism to bring the actual rotation angle back to the allowable range of the target angle; this compensating torque continues to be applied until the manual sends a bolt connection completion signal through the completion button on the controller.

[0016] The torque applied during manual bolt tightening can easily cause the pipe to rotate unexpectedly, leading to misalignment of the aligned bolt holes and affecting bolt insertion and connection quality. To address this, this invention, after the axial travel mechanism pauses and enters standby mode while the gripping unit holds the bolt, continuously receives real-time feedback from the angle encoder. Once the absolute value of the deviation between the actual rotation angle and the target angle exceeds a preset deviation threshold, a compensating torque is applied in the opposite direction via the rotation drive mechanism to bring the actual rotation angle back within the allowable range of the target angle. This compensating torque continues to be applied until the bolt connection is complete. Thus, throughout the entire bolt tightening process, the real-time monitoring by the angle encoder and the active reverse compensation by the rotation drive mechanism dynamically counteract the influence of external torque on the circumferential phase of the pipe, maintaining the alignment of the flange bolt holes at all times. This reduces the difficulty of manual operation and improves the smoothness of bolt installation and connection reliability.

[0017] Preferably, after the axial travel mechanism pauses and enters a standby state while maintaining the gripping state of the gripper, the controller enters a dynamic force holding mode. During the manual tightening of the bolt, the controller continuously receives the contact force value fed back by the force sensor. When the contact force value exceeds a first preset threshold, and the increment of the contact force value relative to the first preset threshold reaches a preset increment threshold, the controller drives the axial travel mechanism to slowly retreat along the axial direction at a preset retreat speed, so that the contact force value decreases and is maintained within a preset force range including the first preset threshold. This dynamic force holding mode continues to operate until the bolt connection is completed by the manual sending a bolt connection completion signal through the completion button on the controller. At this time, the controller exits the mode and controls the gripper to release the clamp.

[0018] When manually tightening bolts, the preload of the bolts and the original thrust of the axial travel mechanism can easily lead to uncontrolled clamping force on the flange surface, potentially damaging the flange or affecting the tightening quality. To address this, this invention, after the axial travel mechanism pauses and enters a standby state while maintaining clamping, activates a dynamic force-holding mode, continuously receiving contact force values ​​from the force sensor. When the contact force exceeds a first preset threshold and the increment reaches a preset increment threshold, the controller drives the axial travel mechanism to slowly retreat axially at a preset retreat speed, reducing the contact force value and maintaining it within the preset force range. This mode continues until the bolt connection is complete. In this way, by monitoring the flange surface pressure in real time through the force sensor, and actively retracting to release excess thrust when the bolt tightening causes pressure to rise, the flange surface maintains a constant, ideal clamping force. This avoids damage to the flange due to excessive pressure, ensures the bolts are reliably tightened to the specified torque, and does not interfere with manual operation.

[0019] Preferably, after the infrared beam sensor is manually removed, the method further includes pre-inserting bolts into the aligned bolt holes, and then the controller automatically performs the first pair of hole confirmation steps and the second pair of hole confirmation steps; after the above steps are completed, a manual continuation signal is allowed. The first hole confirmation step is as follows: the controller drives the axial travel mechanism to move the flange face of the pipe to be connected to the flange face of the installed pipe at a detection speed lower than the normal forward speed, and at the same time continuously monitors the contact force value fed back by the force sensor; if the contact force value always remains below the third preset threshold, the controller determines that the hole is in good condition and there are no foreign objects, and continues to execute the second hole confirmation step; if the contact force value changes abruptly by more than the third preset threshold during the movement, the controller determines that there is bolt hole misalignment or foreign objects, and causes the axial travel mechanism to pause and enter standby state and issue an alarm signal, waiting for manual intervention; wherein, the second preset threshold is less than the third preset threshold, and the third preset threshold is less than the first preset threshold; The second hole confirmation step is as follows: The controller drives the gripping part to reciprocate at a first preset angle range through the rotary drive mechanism, while continuously monitoring the contact force value fed back by the force sensor. The first preset angle range is less than the central angle corresponding to the difference between the bolt hole radius and the bolt radius on the flange bolt hole pitch circle. If the force sensor does not detect a contact force exceeding a second preset threshold during the reciprocating rotation, the controller determines that the hole alignment is good and allows manual transmission of a continuation signal. If the force sensor detects a contact force exceeding the second preset threshold during the reciprocating rotation, the controller determines that the bolt hole has been misaligned and interfered with. At this time, the controller drives the rotary drive mechanism to slowly rotate the gripping part until the contact force detected by the force sensor falls back below the second preset threshold, and records this position as the corrected target angle. The corrected target angle replaces the target angle recorded in claim 3, and then allows manual transmission of a continuation signal.

[0020] After removing the sensor, this invention pre-inserts bolts into the aligned bolt holes. Before pressing the confirmation button, the controller automatically executes a first and a second alignment confirmation step. In the first step, the controller drives the axial travel mechanism to move the flange face of the pipe to be aligned towards the flange face of the installed pipe at a detection speed lower than the normal speed, while monitoring the contact force value fed back by the force sensor. If the contact force remains below a third preset threshold (less than a first preset threshold), the alignment is considered good and there are no foreign objects. If a sudden change occurs, misalignment or foreign objects are identified, the process stops, and an alarm is triggered. In the second step, the controller drives the gripping part to reciprocate at a first preset angle amplitude smaller than the difference between the bolt hole radius and the bolt radius via a rotary drive mechanism, while monitoring the contact force. If no contact force exceeding the second preset threshold is detected, the alignment is considered good. If interference is detected, the rotation is slowed until the contact force falls back below the second preset threshold. This position is recorded as the corrected target angle, replacing the original target angle, and then a continue signal is allowed. In this way, by using pre-inserted bolts as the force transmission medium, the interference force between the bolt and the hole wall is detected by axial movement and small circumferential reciprocating rotation. Secondary confirmation and correction based on force sensing are achieved without infrared feedback, thereby avoiding hole deviation caused by disturbance and ensuring the smooth progress of subsequent axial tightening and bolt insertion.

[0021] Preferably, during the infrared hole alignment process where the controller drives the gripping part to rotate via a rotary drive mechanism, if the gripping part rotates beyond a preset rotation range and still fails to receive a signal from the infrared receiver, where the preset rotation range is the radian of the central angle between two adjacent bolt holes, the controller automatically executes the following fault-tolerant steps: The controller pauses the rotary drive mechanism and drives it to rotate in the opposite direction, searching for infrared signals while rotating in the opposite direction within a preset rotation range. If an infrared signal is received during the reverse rotation, the rotation is stopped and the hole is completed. If no signal is received after rotating within a preset rotation range in both the forward and reverse directions, the controller drives the axial travel mechanism to move the flange face of the pipe to be connected backward along the axial direction by a second backward distance, and then drives the axial travel mechanism to move again towards the installed pipe flange face within the preset distance range at a second forward speed. Resume the forward rotation of the rotary drive mechanism and continue to detect infrared signals; if no signal is received within a preset rotation range in the forward direction, reverse the direction to search again; if no signal is received after repeating the above backward-forward-forward and reverse search steps 2-5 times to reach a preset threshold, the controller will issue an alarm signal to prompt manual intervention.

[0022] During the infrared automatic alignment process, the flange end face may have local burrs, uneven chamfers, or residual deflection angles, causing the infrared light path to be blocked even if the bolt holes are aligned, preventing the signal from being triggered and resulting in alignment failure. To address this, if the gripping part rotates beyond a preset rotation range (i.e., the arc of the central angle between two adjacent bolt holes) and still does not receive an infrared signal, the present invention automatically executes a fault-tolerant step: first, it pauses the rotation and rotates in the opposite direction within the same range to search for a signal; if it still does not receive a signal after rotating a preset range in both directions, it drives the axial travel mechanism to move the flange face of the pipe to be aligned backward along the axial direction by a second backward distance, and then moves it back to the preset spacing range at a second forward speed, and then resumes forward rotation and searches in both directions again; if the above backward-forward-reverse steps are repeated until a preset threshold is reached and there is still no signal, an alarm is issued to prompt manual intervention. In this way, by finely adjusting the axial position of the two flange faces, the infrared light path can avoid local obstruction areas. At the same time, multiple attempts can be made to improve the success rate of hole alignment. This not only avoids automatic hole alignment from stopping due to minor defects, but also prevents infinite loops, thereby improving the robot's adaptability to complex working conditions and operational reliability.

[0023] The present invention has at least the following beneficial effects: First, an axial travel mechanism brings the two flange faces close to a preset distance before rotating them to align the bolt holes, avoiding frictional damage during contact. Simultaneously, an infrared beam sensor passes through the bolt holes for automatic alignment, combined with a force sensor detecting contact force as feedback for proper clamping, forming a step-by-step automated closed-loop control that significantly improves lap joint efficiency and alignment accuracy. Second, an angle encoder is added to the rotary drive mechanism. Upon successful alignment, the target angle is locked and maintained in a closed loop during subsequent axial clamping. Even after the infrared sensor is removed, the circumferential phase of the flange bolt holes remains unchanged, preventing misalignment during clamping. Third, during manual bolt tightening, the angle encoder monitors in real time and compensates for unexpected rotational torque. Simultaneously, a dynamic force-holding mode is entered, actively retracting based on force sensor feedback to maintain a constant flange face clamping force, preventing flange damage and ensuring reliable bolt tightening. Finally, to address potential occlusion or disturbances in the infrared aperture, fault-tolerant and verification steps were designed, including axial fine-tuning backward-forward movement, forward and reverse search, and secondary confirmation and correction based on pre-inserted bolts. These measures effectively improved the robot's adaptability to complex working conditions and operational reliability.

[0024] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of one implementation of the present invention; The components include: 1. Powertrain compartment; 2. Track assembly; 3. Rotary disk; 4. Three-joint robotic arm body; 5. Grabbing unit. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0027] It should be noted that terms such as “having,” “comprising,” and “including” used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0028] This invention provides a tunnel ventilation pipe splicing robot, comprising a powertrain compartment, a frame mounted at the bottom of the powertrain compartment, a walking track assembly mounted at the bottom of the frame, a rotating disk mounted at the top of the frame, a three-joint robotic arm body mounted on the rotating disk, a gripping part mounted at the end of the robotic arm body for clamping the pipe to be spliced, a force sensor mounted on the gripping part, an axial travel mechanism mounted between the bottom of the rotating disk and the frame, a rotary drive mechanism mounted between the gripping part and the end of the robotic arm body, an infrared beam sensor, and a controller. The controller is connected to the walking track assembly, the rotating disk, the robotic arm body, the gripping part, the force sensor, the axial travel mechanism, and the rotary drive mechanism. The mechanism is electrically connected, and the controller can be electrically connected to the matching infrared beam sensor; the transmitting end of the infrared beam sensor can be installed in one of the bolt holes of the flange of the pipe to be docked, and the receiving end of the infrared beam sensor can be installed in the corresponding bolt hole of the flange of the installed pipe. The optical path between the transmitting end and the receiving end is along the axial direction of the bolt hole; after the gripping part clamps the pipe to be docked, the controller drives the main body of the robotic arm to lift the pipe to be docked to a preset height, so that the axial deflection angle between the central axis of the flange of the pipe to be docked and the central axis of the flange of the installed pipe is within a preset angle range, and the radial offset is within a preset offset range; the controller drives the axial travel mechanism to... The flange face of the pipe to be connected moves along the central axis of the pipe (hereinafter referred to as the axial direction) towards the flange face of the installed pipe until the axial distance between the flange face of the pipe to be connected and the flange face of the installed pipe is reduced to within the preset spacing range. The controller then pauses the axial travel mechanism and enters a standby state. The controller drives the gripping part to rotate through the rotary drive mechanism, and at the same time, the infrared beam sensor starts detection. When the flange face of the pipe to be connected rotates until its bolt holes are aligned with the bolt holes of the installed pipe flange, the infrared light emitted by the transmitter passes through the aligned bolt holes on both flanges and is received by the receiver. The controller stops the rotation of the rotary drive mechanism based on the received signal. After the infrared beam sensor is manually removed, the controller... The device automatically executes the hole alignment confirmation step, which is used to verify the alignment status of the bolt holes. After confirmation, a continue signal is sent to the controller via the confirmation button on the operation controller. After receiving the continue signal, the controller continues to drive the axial travel mechanism to move the flange face of the pipe to be connected axially toward the flange face of the installed pipe until the force sensor detects that the contact force between the flange face of the pipe to be connected and the flange face of the installed pipe reaches the first preset threshold. At this point, the controller pauses the axial travel mechanism and enters a standby state while maintaining the clamping state of the gripping part. The bolt connection is completed when the bolt is connected, and the controller releases the gripping part.

[0029] In existing technologies, tunnel ventilation and water pipe splicing construction typically involves manual labor combined with excavators or simple cranes to lift the pipes to be connected. Construction workers visually adjust the parallelism and radial position of the flange faces, relying on experience to repeatedly rotate the pipes to roughly align the bolt holes. Finally, they judge the degree of contact between the flange faces by hand before inserting the bolts. This method is highly dependent on manual experience, has low hole accuracy, and is prone to damaging the flange sealing surface due to repeated adjustments.

[0030] In an embodiment of the present invention, a tunnel ventilation and water pipe splicing robot is provided. For example... Figure 1As shown, the powertrain compartment 1 is a box-shaped structure welded from 10mm thick Q235 steel plates, housing a diesel engine, hydraulic pump station, and battery. A frame is welded to the bottom of the powertrain compartment 1; the frame is a frame structure welded from square steel tubing. A track assembly 2 is mounted at the bottom of the frame. The track assembly 2 uses a commercially available rubber track chassis, model LS-150, whose drive motor is electrically connected to the controller for movement and positioning of the entire machine within the tunnel. A rotating disk 3 is mounted on the top of the frame. The rotating disk 3 is a worm gear type slewing bearing; its inner ring is bolted to the frame, and its outer ring is bolted to the base of the three-joint robotic arm body 4. The drive motor of the rotating disk 3 is a servo motor, electrically connected to the controller, enabling 360-degree continuous rotation. The three-joint robotic arm body 4 is a commercially available three-degree-of-freedom articulated robotic arm. Each joint is driven by an AC servo motor, and an absolute encoder is installed inside each joint. The base of the robotic arm body 4 is mounted on the rotating disk 3, and its end is used to connect to the gripping unit 5. A rotary drive mechanism is installed between the gripping unit 5 and the end of the robotic arm body 4. This mechanism includes a servo motor, a planetary reducer, and gears. The servo motor is a Delta ECMA series with a rated torque of 5 Nm. The reducer has a reduction ratio of 50, and the gear has a module of 2, 60 teeth, and a pitch circle radius of 60 mm. An arc-shaped rack is fixedly mounted on the gripping unit 5. This rack has the same module as the gear and a pitch circle radius of 180 mm. The arc-shaped rack is arranged along an arc with a radius of 180 mm and a central angle of approximately 180°, ensuring that the effective meshing stroke completely covers the rotation range required for the hole. The gear and the arc-shaped rack are externally meshed, with a center distance of 240 mm (i.e., the distance from the center of the gear to the center of the pitch circle of the arc-shaped rack). The gear is mounted at the end of the robotic arm body 4 and is fixed in position. The rotation center of the gripping unit 5 coincides with the center of the pitch circle of the arc-shaped rack, and the arc-shaped rack swings around this center with the gripping unit 5. The distance from the center of the gear to the center of the pitch circle of the arc-shaped rack is 240mm, ensuring correct meshing between the gear and the arc-shaped rack in any rotational position. To withstand the off-center load torque generated by the weight of the pipeline, an arc-shaped guide rail is fixed to the end of the main body 4 of the robotic arm. The arc of the guide rail is the same as that of the arc-shaped rack. The arc-shaped guide rail is made of 45 steel profile with a rectangular cross section, and precision raceways for matching balls are opened on both sides. The surface is hardened. A slider that slides with the arc-shaped guide rail is fixed on the gripping part 5. The slider has balls embedded in it that fit with the raceways, forming a rolling guide rail pair. The gripping part 5 includes a pair of grippers and a hydraulic cylinder that drives the opening and closing of the grippers. The grippers are made of 40Cr, and the gripping surface is vulcanized with 5mm thick polyurethane rubber. The hydraulic cylinder has a diameter of 40mm, a stroke of 80mm, and a working pressure of 16MPa. The hydraulic cylinder is electrically connected to the controller. A force sensor is installed on the lifting unit 5. An S-type tension / compression sensor is selected, with a range of 2000N and an accuracy of 0.2%FS, to detect the axial contact force between the flange faces of the two pipes.An axial travel mechanism is installed between the bottom of the rotating disk 3 and the frame. This mechanism uses an electric push rod (LINAK LA36 model) with a stroke of 300mm, a maximum thrust of 1500N, and a built-in position sensor. One end of the push rod is mounted to the bottom of the rotating disk 3, and the other end is connected to a slide rail on the frame. When the electric push rod extends or retracts, the rotating disk 3 moves axially relative to the frame along the pipe. The infrared photoelectric sensor is an Omron E3Z-T61 type. Both its transmitter and receiver are cylindrical M6 threaded housings, 6mm in diameter and 30mm in length. The transmitter is installed in one of the bolt holes of the flange of the pipe to be connected, and the receiver is installed in the corresponding bolt hole of the flange of the already installed pipe. The optical path between the transmitter and receiver is along the axis of the bolt holes. The controller uses a Siemens S7-1200 series PLC, which integrates digital input / output and analog input modules. The controller is electrically connected to the drive motor of the walking track assembly 2, the servo motor of the rotating disk 3, the servo motors of each joint of the robotic arm body 4, the hydraulic cylinder solenoid valve of the gripping part 5, the force sensor, the electric push rod of the axial walking mechanism, the servo motor of the rotary drive mechanism, and the infrared beam sensor.

[0031] The working process of this embodiment is as follows: First, the pipe to be docked is manually placed between a pair of grippers on the gripping unit 5. The controller issues a clamping command, and the hydraulic cylinder extends to drive the grippers to close, clamping the pipe. After clamping, the controller drives the robotic arm body 4 to lift the pipe to a preset height, which is determined according to the center elevation of the installed pipe, for example, 1.5m from the ground. The controller has pre-stored the position and attitude data of the installed pipe flange in the robot's base coordinate system. During the lifting process, the controller performs closed-loop control through encoder feedback from each joint of the robotic arm body and the stored position and attitude data, ensuring that the axial deflection angle between the center axis of the pipe flange to be docked and the center axis of the installed pipe flange is no greater than ±2°, and the radial offset is no greater than ±5mm. Next, the controller drives the electric push rod of the axial travel mechanism to extend, causing the flange face of the pipe to be docked to move axially towards the flange face of the installed pipe. When the axial distance between the two flange faces shrinks to within the range of 10mm to 20mm, the position sensor built into the electric push rod provides feedback, and the controller causes the axial travel mechanism to pause and enter a standby state. Then, the controller drives the gripping unit 5 to rotate via the servo motor of the rotary drive mechanism at a rotational angular velocity of 5° / s, while the infrared beam sensor begins detection. When the flange to be docked rotates until its bolt holes align with those of the already installed flange, the infrared light emitted by the transmitter passes through the aligned bolt holes on both flanges and is received by the receiver. Upon receiving this signal, the controller immediately stops the rotary drive mechanism and locks the current rotation position. At this point, the transmitter and receiver of the infrared beam sensor installed in the bolt holes are manually removed, and the controller automatically performs the hole alignment confirmation step. After confirmation, a continue signal is sent to the controller via the confirmation button on the controller. Upon receiving the continue signal, the controller again drives the electric push rod of the axial travel mechanism to extend, causing the flange to be docked to continue moving towards the already installed flange. Simultaneously, the controller reads the force sensor values ​​in real time. When the force sensor detects that the contact force between the two flange surfaces reaches 500N, the controller pauses the axial travel mechanism, enters a standby state, and maintains the gripping state of the gripping unit 5. Then, the bolts are manually inserted and tightened. After all the bolts are connected, the operator sends a bolt connection completion signal through the completion button on the controller. The controller then controls the hydraulic cylinder of the gripping unit 5 to retract, and the grippers open to release the clamping, thus completing the splicing operation of one pipe.

[0032] In this embodiment, the rotary drive mechanism includes a servo motor, a reducer, and a gear. The servo motor is installed at the end of the main body of the robotic arm, and the servo motor is connected to the gear through the reducer. An arc-shaped rack is provided on the gripping part, and the arc-shaped rack is arranged along the arc of the rotation direction of the gripping part. The gear meshes with the arc-shaped rack. An arc-shaped guide rail is fixed at the end of the main body of the robotic arm, and a slider that slides with the arc-shaped guide rail is fixed on the gripping part. The arc of the arc-shaped guide rail is the same as the arc of the arc-shaped rack, and the centers of the two coincide at the rotation center of the gripping part. The gripping part includes a pair of grippers and a hydraulic cylinder that drives the pair of grippers to open and close. The hydraulic cylinder is electrically connected to the controller.

[0033] To withstand the eccentric torque generated by the weight of the gripping unit and the clamped pipe, an arc-shaped guide rail is fixedly installed at the end of the robotic arm's main body. A slider that slides in conjunction with this arc-shaped guide rail is fixedly installed on the gripping unit. The curvature of the arc-shaped guide rail is the same as the curvature of the arc-shaped rack, and their centers coincide at the rotation center of the gripping unit. The arc-shaped guide rail is made of 45 steel profile with a rectangular cross-section, and precision raceways for matching balls are opened on both sides, with a surface hardening treatment. The slider that slides in conjunction with the arc-shaped guide rail is fixed on the gripping unit 5, and the slider has balls embedded in it that fit against the raceways, forming a rolling guide pair. This combination of arc-shaped guide rail and slider not only bears the radial and axial loads generated by the weight of the gripping unit and the pipe, but also provides precise guidance for the rotational motion, preventing the gripping unit from swaying or shaking during rotation.

[0034] The gripping unit includes a pair of opposing grippers and a hydraulic cylinder for opening and closing the grippers. The two grippers are hinged to the base of the gripping unit, and the cylinder body of the hydraulic cylinder is hinged to the base. The piston rod of the hydraulic cylinder is connected to the two grippers via a linkage mechanism. When the hydraulic cylinder extends, the two grippers move towards each other to clamp the pipe; when the hydraulic cylinder retracts, the two grippers move away from each other to release the pipe. The hydraulic cylinder is electrically connected to a controller, which controls the opening and closing of the grippers by controlling the solenoid directional valve of the hydraulic cylinder.

[0035] When the controller issues a rotation command, the servo motor starts, and after being reduced in speed and torque by the reducer, it drives the gear to rotate. The gear meshes with the arc-shaped rack arranged along the arc on the gripping part, thereby driving the gripping part to move in an arc around its rotation center. During this process, the arc-shaped guide rail fixed to the end of the robotic arm body and the slider fixed on the gripping part form a rolling guide pair. The arc of the arc-shaped guide rail is the same as the arc of the arc-shaped rack and their centers coincide. The balls or rollers embedded in the slider roll along the guide rail, which not only bears the radial and axial off-center load torque generated by the weight of the gripping part and the clamped pipe, but also provides precise guidance for the rotational motion, so that the gripping part will not wobble or shake when rotating. The grippers of the lifting unit are driven by hydraulic cylinders: the cylinder body is hinged to the base of the lifting unit, and the piston rod is connected to a pair of grippers via a linkage mechanism; the controller controls the hydraulic cylinder to extend via an electromagnetic reversing valve, causing the two grippers to move towards each other to clamp the pipe; when the hydraulic cylinder retracts, the grippers move away from each other to release the pipe. Throughout the process, the meshing of gears and an arc-shaped rack drives the angular rotation, the arc-shaped guide rail and slider ensure motion rigidity and hole alignment accuracy, and the hydraulic cylinder provides a stable clamping force, thus completing the automatic hole alignment operation of the pipe flange within a limited space.

[0036] In another specific embodiment, to address the issue of bolt hole misalignment during axial clamping after the infrared beam sensor is removed, this embodiment adds an angle encoder to the rotary drive mechanism. Existing technology typically involves directly removing the sensor after infrared alignment and then relying on manual visual inspection to maintain flange circumferential alignment. However, due to vibration or changes in pipe clearance, the aligned bolt holes often experience slight misalignment, making subsequent bolt insertion difficult or even requiring readjustment. Therefore, this embodiment uses an absolute rotary encoder as the angle encoder, specifically an Omron E6CP-AG5C model with 12-bit resolution and parallel Gray code output. The stator of the angle encoder is fixedly mounted on the housing at the end of the robotic arm body, and the rotor is fixedly connected to the output shaft of the reducer (i.e., the gear drive shaft) via a coupling. The encoder directly detects the actual rotation angle of the gear, unaffected by the reducer's 50:1 reduction ratio. Since the gear pitch circle radius is 60mm and the arc-shaped rack pitch circle radius is 180mm, their meshing transmission ratio is 3. After the controller reads the encoder angle, the actual rotation angle of the gripping part = encoder-detected angle ÷ 3. The controller uses a Siemens S7-1200 PLC and is expanded with an SM1221 digital input module for reading Gray code signals.

[0037] The working process is as follows: When the infrared beam sensor receives infrared light passing through the two alignment bolt holes, the controller immediately reads the angle value fed back by the angle encoder, divides it by the transmission ratio 3 to convert it into the actual angle of the gripping part, for example, the actual angle is 35°, and records this actual angle value as the target angle and stores it in the PLC's holding register. Subsequently, the transmitter and receiver of the infrared beam sensor are manually removed, and the controller automatically performs the hole alignment status confirmation step. After confirmation, a continue signal is sent through the confirmation button.

[0038] Upon receiving the continuation signal, the controller extends the electric push rod of the axial travel mechanism, causing the flange face of the pipe to be docked to move axially towards the flange face of the already installed pipe. Simultaneously, it continuously reads the real-time angle value from the angle encoder at a 10-millisecond sampling period and converts it into the real-time actual angle of the gripping unit. The controller compares the real-time actual angle value with the stored target angle of 35° and calculates the deviation. When the absolute value of the deviation exceeds the preset deviation threshold of 0.3°, the controller uses a PID algorithm to output a compensation command to the servo motor driver of the rotary drive mechanism. This causes the servo motor to output compensation torque in the opposite direction, driving the gear and the arc rack to move in opposite directions until the real-time actual angle value returns to within the target angle range of ±0.1°.

[0039] The closed-loop control process runs continuously at a frequency of 100 times per second until the force sensor detects that the contact force between the two flange surfaces reaches the first preset threshold of 500N. At this point, the controller pauses the axial travel mechanism, puts it into standby mode, and exits the angle closed-loop holding. In this way, even if the infrared sensor has been removed, the circumferential phase of the flange bolt holes remains unchanged, effectively avoiding misalignment problems during the tightening process.

[0040] In another specific implementation, addressing the difficulty in precisely controlling the deflection angle and radial offset of the flange's central axis when the robotic arm lifts the pipe to be docked to a preset height, this embodiment employs a fusion positioning scheme using a binocular vision camera and a position sensor from the axial travel mechanism. Existing technologies typically rely on manual visual estimation or a monocular camera to roughly estimate the pipe's position, failing to simultaneously obtain its three-dimensional spatial attitude. This results in excessively large deflection angle or radial deviations during subsequent hole alignment, leading to a high failure rate for infrared hole alignment. Therefore, this embodiment installs a binocular vision camera on the top of the frame, using a Hikvision MV-EB0130C industrial camera. The two cameras are spaced 120mm apart, with a fixed baseline, a 6mm lens focal length, and a resolution of 1280×960 pixels. The camera is connected to the controller via a Profinet bus. The controller pre-stores the position and attitude data of the installed pipe flange in the robot's base coordinate system, which can be obtained through initial manual teaching or 3D laser scanning. Simultaneously, the controller stores a fixed axial offset of the pipe flange surface relative to the robotic arm's end-effector coordinate system under gripping conditions, used for kinematic calculations.

[0041] The working process is as follows: After the gripping unit clamps the pipe to be docked, the controller activates the binocular vision camera to acquire images of the flange of the pipe to be docked. The controller calls the stereo matching algorithm in the OpenCV library to calculate the disparity of feature points on the flange edge in the two images, thereby obtaining the three-dimensional coordinates and spatial orientation of the flange in the binocular vision camera coordinate system, including the X, Y, and Z coordinates of the flange center point and the rotation angle around the three coordinate axes. The controller has previously obtained the transformation matrix between the binocular vision camera coordinate system and the robot base coordinate system using the Zhang Zhengyou calibration method, and transforms the three-dimensional position and orientation of the flange to be docked into the robot base coordinate system. The controller compares the transformed pose data of the flange to be docked with the stored pose data of the installed flange, and calculates the deviation value of the axial spatial angle (axial deflection angle) between the two flange center axes, for example, 3.5 degrees, and the radial offset deviation value, for example, 12 mm in the horizontal direction and 8 mm in the vertical direction. Based on these deviation values, the controller obtains the motion compensation of each joint of the robotic arm body through inverse kinematics solution, drives the servo motor of the robotic arm body to move, so that the axial deflection angle of the flange to be docked is gradually reduced to within ±1 degree and the radial offset is reduced to within ±5mm.

[0042] After completing the deflection angle and radial adjustment, the controller again measures the initial axial distance D0 between the flange face of the pipe to be docked and the flange face of the installed pipe using a binocular vision camera. Then, the controller drives the electric push rod of the axial travel mechanism to extend, causing the flange face to be docked to move axially towards the flange face of the installed pipe. Simultaneously, the controller reads the axial movement distance S of the rotating disk relative to the frame in real time based on the position sensor built into the axial travel mechanism. The controller calculates the actual axial distance D between the two flange faces: D = D0 - S. As the axial travel mechanism continues to advance, the controller continuously calculates the D value. When D shrinks to within the preset spacing range of 10mm to 20mm, for example, D=15mm, the controller pauses the axial travel mechanism and enters a standby state. At this point, the distance between the flange face to be docked and the flange face of the installed pipe meets the requirements for infrared alignment, and the deflection angle and radial offset are within the allowable range, providing accurate initial conditions for subsequent automatic alignment.

[0043] In another specific embodiment, to address the problem that the torque applied during manual bolt tightening can easily cause the pipe to rotate unexpectedly, leading to misalignment of the aligned bolt holes, this embodiment further adds a dynamic angle compensation function during the bolt tightening stage, based on the angle encoder closed-loop control of claim 3. In the prior art, manual bolt tightening typically requires another person to support the pipe or use tools to clamp the flange to prevent rotation, which is not only inefficient but also prone to bolt hole misalignment due to torque fluctuations, affecting the subsequent bolt insertion and tightening quality. Therefore, this embodiment adopts a continuous angle compensation control strategy. The angle encoder still uses an Omron E6CP-AG5C absolute rotary encoder, installed in the same position as in the previous embodiment, i.e., the stator is fixed to the end housing of the robotic arm body, and the rotor is connected to the reducer output shaft via a coupling. The servo motor of the rotary drive mechanism is a Delta ECMA-C21010RS type with a rated torque of 10Nm, equipped with an ASD-A2 type driver, supporting torque mode and speed mode switching. The controller is still a Siemens S7-1200 PLC, which sends torque commands to the servo driver through an analog output module.

[0044] The working process is as follows: After the axial travel mechanism pauses and enters standby mode while the gripping unit remains in a clamping state, the controller records the target angle as 35° (the converted actual angle). At this point, the manual bolt tightening stage begins. The controller continuously reads the real-time angle value from the angle encoder at 10-millisecond intervals, converts it into the actual angle of the gripping unit, and then compares it with the target angle of 35° to calculate the absolute value of the deviation. The preset deviation threshold is set at 0.2°, which is the allowable small fluctuation range. When the first bolt is manually tightened, the tangential force applied by the wrench is transmitted to the gripping unit through the pipe, and the controller detects that the actual angle gradually deviates, for example, becoming 35.3°, with an absolute deviation of 0.3°, exceeding the 0.2° threshold. The controller immediately calculates the direction and magnitude of the compensation torque to be applied using a PID algorithm and sends a reverse torque command to the servo driver. The servo motor outputs the reverse torque, which is amplified by the reducer and then drives the gripping unit to move slightly in the opposite direction through gears and an arc-shaped rack until the actual angle falls back to within the range of 35°±0.1°. At this point, the controller stops outputting the compensation torque but continues monitoring. During the tightening of the same bolt, deviations may occur multiple times, and the controller responds in real time. When manually moving to the next bolt, new deviations may also occur, and the controller continuously performs dynamic compensation. This compensation process continues until all bolts are manually tightened, at which point a bolt connection completion signal is sent via the completion button on the controller. Upon receiving the signal, the controller exits the angle compensation mode and then controls the gripping unit to release its clamp. In this way, the circumferential phase of the flange bolt holes is maintained near the target angle throughout the entire bolt tightening process, eliminating the need for manual support and improving the smoothness of bolt installation and connection reliability.

[0045] In another specific embodiment, addressing the problem of uncontrolled flange clamping force caused by the superposition of bolt preload and axial travel mechanism thrust during manual bolt tightening, this embodiment introduces a dynamic force holding mode after the axial travel mechanism pauses and enters a standby state while maintaining clamping. In existing technology, the axial travel mechanism stops and holds the flange after the contact force reaches a first preset threshold. At this point, manual bolt tightening further compresses the flange gasket, causing a sharp increase in contact force, easily exceeding the flange's allowable clamping force range, leading to flange deformation or sealing failure. Therefore, this embodiment employs a force feedback dynamic retraction control strategy. The force sensor used is an S-type tension / compression sensor manufactured by Bengbu Sensor Factory, with a range of 2000N and an accuracy of 0.2%FS. Its signal is converted into a 4-20mA current signal by a transmitter and input to the controller's analog input module. The axial travel mechanism uses an electric push rod, model LINAK LA36, with a stroke of 300mm and a maximum thrust of 1500N. It has a built-in Hall position sensor. One end of the push rod is hinged to the bottom of the rotating disk via a pin, and the other end is hinged to a slide rail on the frame. The motor of the electric push rod is controlled by a controller via a relay module to adjust its forward and reverse rotation and speed. The controller uses a Siemens S7-1200 PLC and includes an SM1231 analog input module for reading force sensor signals.

[0046] The working process is as follows: After receiving the continue signal, the controller drives the axial travel mechanism to advance. When the force sensor detects that the flange surface contact force reaches the first preset threshold of 500N, the controller pauses the axial travel mechanism to enter a standby state and maintains the gripping state of the lifting part. At this time, the controller automatically enters the dynamic force holding mode. The preset incremental threshold is set to 100N, the preset force range is set to 500N to 550N, and the preset retraction speed is 1mm / s. When the operator starts to tighten the first bolt, the clamping force between the flange surfaces gradually increases as the bolt is screwed in. The controller continuously reads the contact force value fed back by the force sensor at a period of 20 milliseconds. Assuming the current contact force is 520N, which is still within the preset force range, the controller does not act. When the operator continues to tighten, the contact force rises to 610N, which exceeds the first preset threshold of 500N and the increment reaches 110N, exceeding the preset incremental threshold of 100N. The controller immediately drives the electric push rod of the axial travel mechanism to slowly retract axially at a speed of 1mm / s. During the retraction process, the controller monitors the contact force value in real time. When the force value drops to 520N, the controller stops retraction. Since the bolts have been tightened to a certain angle, the flange gasket is compressed, and the contact force will not return to 500N after retraction, but will remain at a new equilibrium point. As the operator continues to tighten the same bolt or moves to the next bolt, the contact force may rise again to more than 550N and the increment may exceed 100N. The controller will then trigger retraction again, causing the force value to fall back to the preset force range. Throughout the bolt tightening process, the dynamic force holding mode continues to operate, and the controller continuously performs closed-loop adjustment of "monitoring-judging-retracting-stopping" to keep the flange surface contact force between 500N and 550N. After the operator has completed tightening all bolts and sent a bolt connection completion signal via the completion button on the controller, the controller exits the dynamic force holding mode and then controls the gripping unit to release the clamp. In this way, the bolt preload and the thrust of the axial travel mechanism will not overlap and become uncontrollable. The flange surface always bears a constant ideal clamping force, which avoids flange damage and ensures reliable bolt tightening.

[0047] In another specific implementation, to address the issue that accidental disturbance to the pipe to be connected during manual removal of the infrared beam sensor may lead to slight misalignment of the bolt holes, which may go undetected, this embodiment adds a secondary confirmation and correction step based on pre-inserted bolts after successful infrared alignment. In existing technologies, there is no feedback mechanism after the infrared sensor is removed; axial tightening is performed directly. If the bolt holes are already misaligned at this point, the flange surfaces will scrape against each other during tightening, potentially damaging the bolt hole edges, and manual readjustment after tightening is difficult. Therefore, this embodiment uses pre-inserted bolts as the force transmission medium, detecting interference forces through axial movement and small circumferential rotation, and automatically correcting the alignment status.

[0048] Specifically, after the infrared beam sensor receives the alignment signal and the controller stops rotating the drive mechanism and locks the gripping part, the transmitter and receiver of the infrared beam sensor are manually removed. Then, with the gripping part still clamped and locked, a bolt is manually inserted into the aligned bolt hole. This bolt is a standard M16×60 hexagonal head bolt made of 35CrMo material, and the insertion depth is such that the bolt head is close to the flange surface but not tightened. At this time, the confirmation button on the controller has not been operated. The controller automatically executes the first hole confirmation step: the controller drives the electric push rod of the axial travel mechanism to move a first detection distance toward the flange surface of the installed pipe at a detection speed of 0.5mm / s, which is lower than the normal forward speed. The first detection distance is set to 3mm. At the same time, the controller continuously monitors the contact force value fed back by the force sensor at a period of 10 milliseconds. The third preset threshold is set to 50N, which is much smaller than the first preset threshold of 500N. If the contact force value fed back by the force sensor remains below 50N throughout the entire 3mm movement, it indicates that the pre-inserted bolt can smoothly enter the corresponding bolt hole of the installed pipe flange without axial misalignment or foreign object obstruction. The controller determines that the hole alignment is good and continues to execute the second hole alignment confirmation step. If the contact force suddenly exceeds 50N during the movement, for example, reaching 80N, the controller determines that there is bolt hole misalignment or foreign object in the hole. It immediately pauses the axial travel mechanism and enters a standby state, issuing an audible and visual alarm signal through the controller's alarm light and buzzer, awaiting manual intervention.

[0049] If the first pair of holes is confirmed, the second pair of holes is confirmed: the controller drives the gripping part to reciprocate at a first preset angle range via the servo motor of the rotary drive mechanism. The first preset angle range is set to 0.3 degrees, which is less than the difference between the bolt hole radius and the bolt radius. Typically, the diameter of an M16 bolt hole is 18mm, and the bolt diameter is 16mm, with a radius difference of 1mm. This corresponds to an arc length of approximately 0.38 degrees when the flange pitch circle radius is approximately 150mm. Therefore, 0.3 degrees is sufficient to detect circumferential interference. The reciprocating rotation frequency is once per second, i.e., first rotating 0.3 degrees in the forward direction, then rotating 0.3 degrees in the reverse direction, and returning to the original position. During the reciprocating rotation, the controller continuously monitors the contact force value fed back by the force sensor, and the second preset threshold is set to 30N. If the force sensor never detects a contact force exceeding 30N during the reciprocating rotation, it indicates that the pre-inserted bolt has free space in the circumferential direction, the hole condition is maintained well, and the controller allows manual transmission of a continue signal, i.e., manual operation of the confirmation button on the controller. If the force sensor detects a contact force exceeding 30N during reciprocating rotation, for example, reaching 45N, it is determined that circumferential misalignment interference has occurred in the bolt hole, and the bolt is in contact with the hole wall. At this point, the controller does not stop but drives the rotary drive mechanism to slowly rotate the gripping unit at a speed of 0.2 degrees per second, in the opposite direction to the direction causing the interference (first, the rotation direction when the contact force exceeds the threshold is recorded, and then the rotary drive mechanism is driven to slowly rotate the gripping unit in the opposite direction at a speed of 0.2 degrees per second), while simultaneously monitoring the force sensor in real time. When the contact force detected by the force sensor falls below 30N, the current angle encoder reading is recorded and converted into an actual angle, for example, 36.2° (actual angle), as the corrected target angle. This value replaces the original target angle of 35° previously recorded and stored in the controller when triggered by the infrared beam sensor. The controller then stops rotating and allows manual transmission of a continue signal. The corrected target angle will be used for closed-loop maintenance during subsequent axial clamping and bolt tightening processes. Through the above-mentioned secondary confirmation and correction, even if a slight disturbance occurs after the infrared sensor is removed, it can be automatically corrected before compaction, ensuring the smooth progress of subsequent processes.

[0050] In another specific implementation, to address the problem that during the infrared automatic alignment process, the infrared light path may be blocked due to local burrs, uneven chamfering, or residual deflection angle on the flange end face, preventing signal triggering even when the bolt holes are aligned, this embodiment designs a fault-tolerant procedure. Existing technologies typically trigger an alarm and require manual intervention after a failed rotational alignment, or simply repeat forward rotation, failing to resolve the light path blockage problem and causing the automated process to be interrupted. Therefore, this embodiment utilizes axial fine-tuning to change the relative position of the two flange faces, combined with forward and reverse searching and multiple attempts, to improve the alignment success rate.

[0051] In this embodiment, the Omron E3Z-T61 infrared beam sensor is still used. The transmitter is installed in one of the bolt holes of the flange to be docked, and the receiver is installed in the corresponding bolt hole of the flange already installed. The optical path is along the axis of the bolt hole. The preset rotation range is set to the radian of the central angle between two adjacent bolt holes. For the case of 8 bolt holes evenly distributed on the flange, the central angle between adjacent holes is 45 degrees. When the controller drives the rotation drive mechanism to perform infrared alignment, it rotates forward at an angular velocity of 5 degrees per second, while monitoring the signal from the infrared receiver. If the gripping part rotates continuously for more than 45 degrees without receiving a signal, a fault-tolerant step is triggered.

[0052] First, the controller pauses the rotary drive mechanism and immediately drives it to rotate in the opposite direction, searching for an infrared signal within a 45-degree reverse rotation range. The reverse rotation speed is also 5 degrees per second. If an infrared signal is received during the reverse rotation, the rotation stops and the alignment is considered complete. If no signal is received after rotating a preset 45-degree range in both directions, the controller drives the electric push rod of the axial travel mechanism to retract the flange face of the pipe to be aligned axially a second retraction distance, set to 5mm. The retraction speed is the normal speed of 2mm / s. After retraction, the controller drives the axial travel mechanism to move towards the installed pipe flange face again at a second forward speed to within a preset distance range. The second forward speed is set to 1mm / s, slightly slower than the normal forward speed, to avoid collisions during rapid approach. When the distance between the two flange faces returns to the preset distance range of 10mm to 20mm, the rotary drive mechanism resumes forward rotation, continuing to detect infrared signals at a speed of 5 degrees per second. If no signal is received within a preset 45-degree rotation range in the forward direction, the search is reversed again. The above backward-forward-reverse search steps constitute one complete cycle. The preset threshold is set to 3 cycles. If no infrared signal is received after repeating 3 cycles, the controller will issue an audible and visual alarm signal to prompt manual intervention and simultaneously stop the automatic hole alignment process.

[0053] In the actual assembly, the electric push rod of the axial travel mechanism uses a LINAK LA36, which has a built-in position sensor. Retreating 5mm and advancing to the preset distance are both achieved through closed-loop position control. The controller uses a Siemens S7-1200 PLC, which reads the switching signal from the infrared receiver via a digital input module. Throughout the fault-tolerant process, the controller records the result of each attempt but does not change the recorded target angle. Through the above axial fine-tuning, the position of the infrared light path relative to the burrs or chamfers when passing through the two flange bolt holes can be changed, thus avoiding local obstruction, while increasing the success probability through multiple attempts. If it still fails, an alarm prompts manual inspection of the flange end face for serious defects, avoiding infinite loops.

[0054] Experimental Example In a high-pressure ventilation and water pipe installation project in a tunnel, the pipe diameter was 200mm, and eight bolt holes were evenly distributed on the flange. Construction workers used the tunnel ventilation and water pipe splicing robot described in this invention to splice the pipes. First, the robot moved to the location of the pipes to be spliced ​​via its tracked assembly. The diesel engine in the powertrain compartment provided power to the hydraulic pump station and battery. The controller drove the three-joint robotic arm to move the gripping part above the pipe to be spliced. The hydraulic cylinder extended, and a pair of grippers closed to clamp the pipe. The polyurethane rubber on the inner wall of the grippers adhered to the pipe wall. The clamping force was monitored in real time through hydraulic system pressure feedback to ensure no damage to the pipe wall.

[0055] After clamping, the binocular vision camera on top of the frame begins operation. The Hikvision MV-EB0130C camera acquires images of the flange to be docked at a rate of 15 frames per second. The controller calculates the flange's 3D position and orientation in the camera coordinate system using a stereo matching algorithm, transforms it to the robot's base coordinate system using a calibration transformation matrix, and compares it with pre-stored pose data of the installed flange. This yields an axial deflection angle deviation of 2.5 degrees and radial offsets of 10mm horizontally and 6mm vertically. The controller then uses inverse kinematics to drive the servo motors of the three joints of the robotic arm, reducing the deflection angle to within ±1 degree and the radial offset to within ±3mm. Subsequently, the controller again measures the initial axial distance D0 between the flange to be docked and the installed flange using the binocular vision camera, finding it to be 45mm. The controller then extends the LINAK LA36 electric actuator of the axial travel mechanism, simultaneously reading the movement distance S in real time based on the position sensor built into the electric actuator. When S=30mm, the current axial distance D = D0 - S = 15mm is calculated, reaching the preset spacing range, and the controller causes the axial travel mechanism to pause and enter standby state.

[0056] Next, the automatic hole alignment stage begins. The Delta ECMA servo motor of the rotary drive mechanism drives the gear and the arc-shaped rack via a reducer, causing the gripping unit to rotate forward at 5 degrees per second. Simultaneously, the Omron infrared beam sensor begins detection. Due to a tiny burr on the flange end face, the infrared light is blocked when the bolt holes are actually aligned, and the gripping unit rotates more than 45 degrees without receiving a signal. The controller automatically executes a fault-tolerant procedure: first, it rotates 45 degrees in the opposite direction without receiving a signal; then, the axial travel mechanism retreats 5mm and then advances at 1mm / s to a 15mm gap, resuming forward rotation. On the second attempt, the infrared light successfully passes through the aligned bolt holes, the receiver receives a signal, the controller stops rotating, and records the converted actual angle of 35° as the initial target angle. This target angle can be corrected and updated in subsequent hole alignment status confirmation steps. After manually removing the infrared sensor transmitter and receiver, an M16×60 bolt is pre-inserted into the aligned bolt holes. The controller automatically performs the first pair of hole verifications: the axial travel mechanism advances 3mm at a speed of 0.5mm / s, and the force sensor detects that the contact force is consistently below 50N, indicating no axial misalignment. Next, the controller performs the second pair of hole verifications: the rotary drive mechanism rotates back and forth twice at an amplitude of 0.3 degrees, and the force sensor does not detect an interference force exceeding 30N, indicating good circumferential hole alignment. At this point, the controller allows manual transmission of a continue signal.

[0057] After the manual confirmation button is pressed, the controller drives the axial travel mechanism to continue advancing, while simultaneously reading the angle encoder at 10-millisecond intervals and converting it into the actual angle. A PID closed-loop system maintains the gripping unit at the target angle of 35°. When the force sensor detects that the flange contact force reaches 500N, the controller pauses the axial travel mechanism, entering a standby state and maintaining clamping, while simultaneously entering dynamic force holding mode and angle compensation mode. The manual operator begins tightening the first bolt. As the bolt is screwed in, the contact force increases from 500N to 610N, an increase of 110N exceeding the preset increment threshold of 100N. The controller immediately drives the electric push rod to retract at 1mm / s, stopping when the force drops to 520N. Simultaneously, the tightening torque causes the actual angle of the gripping unit to deviate to 35.3°, a deviation of 0.3° exceeding the 0.2° threshold. The controller outputs a reverse compensation torque via the servo motor, returning the angle to 35°. The remaining seven bolts are tightened manually in sequence. During this process, the controller continuously maintains dynamic force and compensates for angles, keeping the flange contact force between 500N and 550N, and controlling the angle deviation within ±0.1°. After all bolts are tightened, the operator presses the "complete" button. The controller then exits all holding modes, the hydraulic cylinder retracts, and the grippers open to release the clamp. The robot moves to the next pipe to be connected and repeats the above process. The entire overlapping process eliminates the need for manual visual adjustment of bolt holes or judgment of tightening force by feel. The overlapping time for a single pipe is reduced by approximately 60% compared to traditional methods, and no bolt insertion difficulties or flange damage due to hole misalignment occur.

[0058] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Further modifications can be readily implemented by those skilled in the art.

Claims

1. A tunnel ventilation and water pipe splicing robot, characterized in that: The system includes a powertrain compartment, a frame mounted at the bottom of the powertrain compartment, a track assembly mounted at the bottom of the frame, a rotating disk mounted at the top of the frame, a three-joint robotic arm body mounted on the rotating disk, a gripping part mounted at the end of the robotic arm body for holding the pipe to be docked, a force sensor mounted on the gripping part, an axial travel mechanism mounted between the bottom of the rotating disk and the frame, a rotary drive mechanism mounted between the gripping part and the end of the robotic arm body, an infrared beam sensor, and a controller. The controller is electrically connected to the track assembly, the rotating disk, the robotic arm body, the gripping part, the force sensor, the axial travel mechanism, and the rotary drive mechanism, and can also be electrically connected to the matching infrared beam sensor. The transmitting end of the infrared beam sensor can be installed in one of the bolt holes of the flange of the pipe to be docked, and the receiving end of the infrared beam sensor can be installed in the corresponding bolt hole of the flange of the pipe already installed. The optical path between the transmitting end and the receiving end is along the axial direction of the bolt hole. After the gripping unit clamps the pipe to be docked, the controller drives the main body of the robotic arm to lift the pipe to be docked to a preset height, so that the axial deflection angle between the center axis of the flange of the pipe to be docked and the center axis of the flange of the installed pipe is within a preset angle range, and the radial offset is within a preset offset range. The controller drives the axial travel mechanism to move the flange face of the pipe to be connected axially toward the flange face of the installed pipe until the axial distance between the flange face of the pipe to be connected and the flange face of the installed pipe is reduced to within the preset spacing range. The controller then pauses the axial travel mechanism and enters the standby state. The controller drives the gripping part to rotate through the rotary drive mechanism. At the same time, the infrared beam sensor starts to detect. When the flange to be docked rotates until its bolt holes are aligned with the bolt holes of the installed flange, the infrared light emitted by the transmitter passes through the aligned bolt holes on the two flanges and is received by the receiver. The controller stops the rotation of the rotary drive mechanism according to the received signal. After the infrared beam sensor is manually removed, the controller automatically executes the hole alignment confirmation step. The hole alignment confirmation step is used to verify the bolt hole alignment status. After the confirmation is completed, a continue signal is sent to the controller by operating the confirmation button on the controller. After receiving the continue signal, the controller continues to drive the axial travel mechanism to move the flange face of the pipe to be connected axially toward the flange face of the installed pipe until the force sensor detects that the contact force between the flange face of the pipe to be connected and the flange face of the installed pipe reaches the first preset threshold. At this point, the controller causes the axial travel mechanism to pause and enter the standby state while maintaining the clamping state of the gripping part. The gripping part will release the clamping part after the operator sends a bolt connection completion signal to the controller via the completion button on the controller.

2. The tunnel ventilation and water pipe splicing robot according to claim 1, characterized in that: The rotary drive mechanism includes a servo motor, a reducer, and gears. The servo motor is installed at the end of the main body of the robotic arm and is connected to the gears through the reducer. An arc-shaped rack is provided on the gripping part, and the arc-shaped rack is arranged along the arc of the rotation direction of the gripping part. The gears mesh with the arc-shaped rack. An arc-shaped guide rail is fixed at the end of the main body of the robotic arm, and a slider that slides with the arc-shaped guide rail is fixed on the gripping part. The arc of the arc-shaped guide rail is the same as the arc of the arc-shaped rack, and the centers of the two coincide at the rotation center of the gripping part. The gripping part includes a pair of grippers and a hydraulic cylinder that drives the pair of grippers to open and close. The hydraulic cylinder is electrically connected to the controller.

3. The tunnel ventilation and water pipe splicing robot according to claim 1 or 2, characterized in that: The rotary drive mechanism is also equipped with an angle encoder for real-time detection of the rotation angle of the grabbing part; When the infrared beam sensor receives an infrared light signal, the controller records the angle value fed back by the angle encoder at this time as the target angle. After the infrared beam sensor is manually removed and a continue signal is sent, the controller continues to drive the axial walking mechanism. At the same time, based on the real-time feedback of the angle encoder, the controller uses the rotation drive mechanism to control the gripping part to maintain the target angle in a closed loop until the force sensor detects that the contact force reaches the first preset threshold.

4. The tunnel ventilation and water pipe splicing robot according to claim 1, characterized in that: The controller drives the robotic arm to lift the pipe to be docked to a preset height, ensuring that the axial deflection angle between the center axis of the flange of the pipe to be docked and the center axis of the already installed flange are within a preset angle range and the radial offset is within a preset offset range. The specific implementation method is as follows: The frame is equipped with a binocular vision camera, and the axial walking mechanism has a built-in position sensor to detect the axial movement distance of the rotating disk relative to the frame. The controller stores the position and attitude data of the installed pipe flange in the robot's base coordinate system, as well as the fixed axial offset of the pipe flange surface to be docked relative to the coordinate system of the end of the robotic arm under the gripping state of the gripping part. After the gripper grasps the pipe to be docked, the controller controls the binocular vision camera to acquire images of the flange of the pipe to be docked. A stereo matching algorithm is used to calculate the 3D position and spatial orientation of the flange in the binocular vision camera coordinate system. The controller then transforms the 3D position and spatial orientation of the flange to be docked into the robot's base coordinate system based on the calibration transformation matrix between the binocular vision camera coordinate system and the robot's base coordinate system. The controller compares the position and orientation data of the flange to be docked with that of the already installed flange, calculating the axial deflection angle deviation and radial offset deviation between the two flange center axes. Based on the calculated deviations, the controller uses inverse kinematics to obtain the motion compensation amounts for each joint of the robotic arm, driving the robotic arm to move so that the axial deflection angle between the center axis of the flange to be docked and the center axis of the already installed flange are within a preset angle range and the radial offset is within a preset offset range. After the axial deflection angle and radial offset are adjusted, the controller measures the initial axial distance D0 between the flange face of the pipe to be docked and the flange face of the installed pipe again through a binocular vision camera. The controller drives the axial travel mechanism to move the flange face of the pipe to be docked axially toward the flange face of the installed pipe, and at the same time reads the axial movement distance S in real time according to the position sensor built into the axial travel mechanism. The controller calculates the current axial distance D = D0 - S. When D shrinks to within the preset spacing range, the controller makes the axial travel mechanism pause and enter the standby state.

5. The tunnel ventilation and water pipe splicing robot according to claim 3, characterized in that: After the axial travel mechanism pauses and enters standby mode while maintaining the gripping state of the gripping part, during the manual tightening of the bolts, the controller continuously receives real-time feedback from the angle encoder. When the absolute value of the deviation between the actual rotation angle of the gripping part and the target angle exceeds the preset deviation threshold, the controller applies a compensating torque in the opposite direction through the rotation drive mechanism to bring the actual rotation angle back to the allowable range of the target angle. This compensating torque continues to be applied until the manual sends a bolt connection completion signal through the completion button on the controller.

6. The tunnel ventilation and water pipe splicing robot according to claim 1, characterized in that: After the axial travel mechanism pauses and enters standby mode while maintaining the gripping state, the controller enters dynamic force holding mode. During the manual tightening of the bolt, the controller continuously receives the contact force value fed back by the force sensor. When the contact force value exceeds the first preset threshold and the increment of the contact force value relative to the first preset threshold reaches the preset increment threshold, the controller drives the axial travel mechanism to slowly retreat along the axial direction at a preset retreat speed, so that the contact force value decreases and is maintained within the preset force range including the first preset threshold. This dynamic force holding mode continues to run until the bolt connection is completed by the manual sending a bolt connection completion signal through the completion button on the controller. At this time, the controller exits the mode and controls the gripping unit to release the clamp.

7. The tunnel ventilation and water pipe splicing robot according to claim 3, characterized in that: After the infrared beam sensor is manually removed, the process includes pre-inserting bolts into the aligned bolt holes, and then the controller automatically performs the first pair of hole confirmation steps and the second pair of hole confirmation steps; after the above steps are completed, the manual transmission of the continuation signal is allowed. The first hole confirmation step is as follows: the controller drives the axial travel mechanism to move the flange face of the pipe to be connected to the flange face of the installed pipe at a detection speed lower than the normal forward speed, and at the same time continuously monitors the contact force value fed back by the force sensor; if the contact force value always remains below the third preset threshold, the controller determines that the hole is in good condition and there are no foreign objects, and continues to execute the second hole confirmation step; if the contact force value changes abruptly by more than the third preset threshold during the movement, the controller determines that there is bolt hole misalignment or foreign objects, and causes the axial travel mechanism to pause and enter standby state and issue an alarm signal, waiting for manual intervention; wherein, the second preset threshold is less than the third preset threshold, and the third preset threshold is less than the first preset threshold; The second hole confirmation step is as follows: The controller drives the gripping part to reciprocate at a first preset angle range through the rotary drive mechanism, while continuously monitoring the contact force value fed back by the force sensor. The first preset angle range is less than the central angle corresponding to the difference between the bolt hole radius and the bolt radius on the flange bolt hole pitch circle. If the force sensor does not detect a contact force exceeding a second preset threshold during the reciprocating rotation, the controller determines that the hole alignment is good and allows manual transmission of a continuation signal. If the force sensor detects a contact force exceeding the second preset threshold during the reciprocating rotation, the controller determines that the bolt hole has been misaligned and interfered with. At this time, the controller drives the rotary drive mechanism to slowly rotate the gripping part until the contact force detected by the force sensor falls back below the second preset threshold, and records this position as the corrected target angle. The corrected target angle replaces the target angle recorded in claim 3, and then allows manual transmission of a continuation signal.

8. The tunnel ventilation and water pipe splicing robot according to claim 1, characterized in that: During the infrared hole alignment process, if the controller drives the gripping part to rotate via a rotary drive mechanism and fails to receive a signal from the infrared receiver even after the gripping part has rotated beyond a preset rotation range (the preset rotation range is the radian of the central angle between two adjacent bolt holes), the controller will automatically execute the following fault-tolerant steps: The controller pauses the rotary drive mechanism and drives it to rotate in the opposite direction, searching for infrared signals while rotating in the opposite direction within a preset rotation range. If an infrared signal is received during the reverse rotation, the rotation is stopped and the hole is completed. If no signal is received after rotating within a preset rotation range in both the forward and reverse directions, the controller drives the axial travel mechanism to move the flange face of the pipe to be connected backward along the axial direction by a second backward distance, and then drives the axial travel mechanism to move again towards the installed pipe flange face within the preset distance range at a second forward speed. Resume the forward rotation of the rotary drive mechanism and continue to detect infrared signals; if no signal is received within a preset rotation range in the forward direction, reverse the direction to search again; if no signal is received after repeating the above backward-forward-forward and reverse search steps 2-5 times to reach a preset threshold, the controller will issue an alarm signal to prompt manual intervention.

Images