A coiled super-redundant serpentine robot for internal inspection of oil-immersed transformers

Abstract

The present application relates to the field of robot technology, especially to a kind of for oil-immersed transformer internal inspection coiled super-redundant snake robot, including conveying mechanism, robot and linkage control system;Linkage control system includes controller and multiple sensors;Conveying wheel disc control module contains first control unit, for planning into posture and initial rotational speed;Second control unit, based on the instantaneous value of moment and posture angle deviation determination jam, control conveying wheel disc intermittent reverse and drive joint module to execute swing every cycle increment periodic swing, make swing and reverse synergistic effect on jam position;Third control unit, when reaching preset depth, reverse and recover redundant length to eliminate pre-tightening force, and complete recovery.The present application realizes accurate access, autonomous escape and stable recovery in the narrow space of transformer.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more particularly to a coiled, super-redundant snake robot for internal inspection of oil-immersed transformers. Background Technology

[0002] Oil-immersed transformers are one of the core pieces of equipment in power systems. Their internal structure is complex, the space is confined, and they are filled with insulating oil. To ensure the safe operation of transformers, it is necessary to regularly inspect and maintain key components such as the internal windings, core, and clamps. Traditional inspection methods often involve manual entry or rigid robotic arms, which suffer from poor safety and insufficient accessibility.

[0003] In recent years, robots, due to their flexibility and high degree of freedom, have been increasingly used for inspection in confined spaces. However, existing robots still face the following problems when applied to the internal inspection of oil-immersed transformers: 1. In the existing technology, when the robot enters the transformer chamber, there is a lack of effective transmission and attitude control mechanism, making it difficult to achieve accurate positioning and stable movement in the narrow and tortuous oil passage; 2. In the existing technology, the robot's ability to autonomously escape when it gets stuck with internal components of the transformer (such as windings and insulating paperboard) during its movement is not considered, which makes the robot easy to get trapped in the cavity. 3. In the prior art, the tail of the robot is usually rigidly connected to the conveying mechanism. When the entry depth is large, the preload of the tail affects the flexibility of the joints, and it is inconvenient to store when not in use and occupies a lot of space.

[0004] Therefore, how to develop a robot suitable for internal inspection of oil-immersed transformers has become a technical problem that needs to be solved. Summary of the Invention

[0005] To address this, the present invention provides a coiled, super-redundant snake-like robot for internal inspection of oil-immersed transformers. Through the coordinated design of the conveying mechanism, the robot, and the linkage control system, it achieves precise entry, autonomous escape, and stable recovery in confined spaces.

[0006] To achieve the above objectives, the present invention provides a coiled, super-redundant snake robot for internal inspection of oil-immersed transformers, comprising: The conveying mechanism, which is used to drive the robot into the transformer chamber, includes a bracket for mounting the conveyor wheel, a motor 1 for driving the conveyor wheel to rotate, and a fixed assembly for connecting to the robot's tail shaft. The robot consists of several articulated joint modules that are hinged together in sequence. Each articulation module is equipped with an attitude sensor and a joint torque sensor. When the robot is not in operation, it is wrapped and stored around the edge of the conveyor wheel. The linkage control system includes a controller, a speed sensor and a torque sensor mounted on the conveyor wheel, and an attitude sensor and a joint torque sensor that are electrically connected to the controller respectively. The transfer wheel control module includes a first control unit for determining the initial posture of the robot entering the transformer chamber and the initial rotation speed of the transfer wheel based on path planning at maintenance and inspection points; a second control unit for controlling the transfer wheel to intermittently reverse to provide a return stroke when the robot is stuck, based on the instantaneous torque value and attitude angle deviation of any joint module of the robot, and controlling the joint module and its adjacent joint modules to perform a periodic swinging escape action with progressively increasing swing amplitude, so that the swinging escape action and the intermittent reversal work together at the stuck position; and a third control unit for stopping the rotation of the transfer wheel when the cumulative entry depth of the robot reaches a preset depth, and simultaneously controlling the transfer wheel to reverse to retract the redundant length to eliminate the preload between the fixed component and the robot tail, and controlling the transfer wheel to reverse to retract the robot when the robot completes maintenance and inspection.

[0007] Furthermore, the second control unit determines that the robot is stuck based on the results that the instantaneous torque value fed back by the joint torque sensor is greater than a preset multiple of the rated torque and the duration is greater than a preset time, and the attitude angle deviation fed back by the attitude sensor is greater than a preset angle deviation.

[0008] Furthermore, in response to the robot getting stuck, the second control unit controls the transmission wheel to rotate intermittently, causing the robot to retreat a preset distance and then stop rotating. It also controls the stuck joint module to sequentially transmit periodic swings with progressively increasing amplitudes towards the tail.

[0009] Furthermore, when the second control unit controls the joint module to perform a periodic swinging escape action with a swing amplitude that increases periodically, the swing amplitude increase period of the swinging escape action is synchronized with the pause period of the intermittent reversal in time, so that the swinging escape action and the intermittent reversal work together to act on the stuck position.

[0010] Furthermore, the conveyor wheel is also equipped with an encoder for detecting the robot's release length, and the controller determines the robot's cumulative entry depth based on the feedback signal from the encoder.

[0011] Furthermore, the third control unit responds to the second control unit completing the escape action by comparing the cumulative entry depth with the preset entry depth.

[0012] Furthermore, based on the result that the robot's cumulative entry depth reaches a preset proportion of its total body length, the third control unit controls the transmission wheel to reverse to eliminate the preload between the fixing component and the robot's tail.

[0013] Furthermore, in response to the robot's command, the third control unit controls the reverse linear speed of the transfer wheel to be greater than the robot's autonomous forward linear speed.

[0014] Furthermore, the edge of the conveyor wheel is provided with a spiral storage groove for storing the robot, and the storage groove is provided with rolling elements to reduce frictional resistance.

[0015] Furthermore, the storage slot is also equipped with a clamping roller. After the third control unit controls the fixing component to detach from the robot tail, it controls the clamping roller to clamp the recovered robot part with a preset torque.

[0016] Compared with existing technologies, this invention solves the technical problems of traditional rigid arms being unable to enter the narrow chambers of transformers, and the safety risks and poor accessibility of manual inspection by setting up a conveying mechanism consisting of a support, motor, conveying wheel, and fixing components. The robot is spirally wound and stored on the edge of the conveying wheel in a non-working state. This conveying mechanism uses a wheel-type storage structure, utilizing a motor to drive the conveying wheel to achieve orderly release and retrieval of the robot, avoiding twisting and entanglement caused by a lack of guidance during entry. The fixing components connect to the robot's tail shaft during the initial release phase, providing tail constraint and preventing the robot from detaching from the wheel due to inertia at the moment of release. This achieves the technical effects of compact robot storage, orderly release, and smooth entry, laying a mechanical foundation for subsequent precise control.

[0017] Furthermore, by configuring the robot as a highly redundant structure composed of several sequentially hinged joint modules, and by installing attitude sensors and joint torque sensors within each joint module, the technical problems of existing technologies—namely, the inability to perceive the attitude and force state of each segment of the robot in real time and the inability to predict the risk of jamming—are solved. The attitude sensor employs a nine-axis inertial measurement unit, outputting the absolute attitude angles of each joint module in three-dimensional space in real time. The joint torque sensor obtains the current load torque borne by each joint module by detecting the current feedback of the joint drive motor and combining it with the reduction ratio calculation. Both are synchronously sampled in the controller with a control cycle of 20ms, thereby achieving millisecond-level real-time perception of the motion and force state of each joint of the robot, providing an accurate data source for subsequent jamming identification and escape control.

[0018] Furthermore, by setting up a linkage control system, the controller, the speed and torque sensors on the transfer wheel, and the attitude and joint torque sensors in each joint module are electrically connected. A transfer wheel control module containing first, second, and third control units is constructed, solving the technical problem of the transfer mechanism and the robot body operating independently and lacking coordination. This linkage control system adopts a master-slave control architecture, with the controller acting as the master control unit. It synchronously collects sensor data from the transfer wheel and all joint modules at a control frequency of 50Hz and issues control commands to the transfer wheel motor and the drive motors of each joint module. This ensures that the rotation of the transfer wheel and the robot's joint movements are precisely coordinated in timing, achieving a closed-loop collaborative control effect throughout the entire process of transfer—movement—perception—judgment—escape—recovery.

[0019] Furthermore, by determining the robot's initial posture and the initial rotation speed of the conveyor wheel based on maintenance and inspection points in the first control unit, the technical problems of lack of posture pre-adaptation before robot entry and easy interference with the chamber entrance due to improper initial posture in the prior art are solved. Based on the azimuth and pitch angles of the transformer chamber entrance and the orientation of the first section of the internal oil passage, the first control unit calculates the initial posture angle that the robot's first joint module should maintain during the path planning stage. Simultaneously, based on the length of the entrance section and the robot's joint driving capability, the optimal initial rotation speed of the conveyor wheel is matched, enabling the robot to enter the chamber in a posture-matched and speed-adapted manner. This achieves the technical effect of eliminating posture interference risks and improving entrance throughput during the entry stage.

[0020] Furthermore, by using the second control unit, based on the conditions that the instantaneous torque value fed back by the joint torque sensor is greater than 1.5 times the rated torque and lasts for more than 0.3 seconds, and the attitude angle deviation fed back by the attitude sensor is greater than ±15°, the robot is judged to be stuck. This solves the technical problem in the prior art that it cannot distinguish between instantaneous impact and continuous stuckness, and that it is easy to trigger escape actions by accidental touch. The principle of this judgment logic is as follows: 1.5 times the rated torque corresponds to the upper limit of the elastic deformation of the joint module. If it is greater than this value, it indicates that the load has significantly exceeded the normal operating range; the 0.3-second time window corresponds to 15 control cycles (control cycle 20ms), which is sufficient to cover two complete sampling and control response cycles to filter out instantaneous impact signals with a duration of less than 0.1 seconds; the ±15° attitude angle deviation threshold is determined based on the internal space constraint analysis of the transformer. If it is greater than this value, it indicates that the joint module has lost effective tracking of the command trajectory. Only when all three conditions are met simultaneously is it judged as a true stuckness, thus achieving the technical effect of high sensitivity and low false alarm rate in stuckness identification.

[0021] Furthermore, by intermittently reversing the control wheel in the second control unit after determining jamming, the robot retreats 15mm (a preset retreat distance) and stops rotating. The jammed joint modules are then controlled to sequentially transmit periodic swings with progressively increasing amplitudes towards the tail, solving the technical problems of continuous pushing exacerbating jamming or blind retreating failing to escape in existing technologies. The 15mm retreat distance is based on a 20-30mm spacing between adjacent joint modules. This distance is sufficient to allow the jammed joint module to move away from the interference point while avoiding excessive retreat that could cause new posture deviations in subsequent joint modules. The intermittent reversal uses an alternating retreat-stop-retreat pattern, introducing a pause after each retreat to create a static condition for swinging escape. The swing transmission direction is chosen to be sequentially transmitted towards the tail, causing the joint modules behind the jamming point to form a wave-like motion. This transmits the swing energy step-by-step along the robot body and concentrates it at the jamming position, rather than dissipating it towards the head, thus achieving a phased escape effect of first retreating to release the pressure and then swinging to concentrate the impact.

[0022] Furthermore, by synchronizing the swing amplitude increase cycle of the swing escape action with the intermittent reversal pause period in the second control unit, the swing amplitude increases from ±5° to ±20° in cycles, with a frequency of 0.5Hz, solving the technical problems of dispersed force and disordered timing in the existing technology. The principle of this timing synchronization is as follows: after the conveyor wheel reverses and moves backward, it enters a pause period. At this time, the robot body is in a stationary state. During this pause period, the controller initiates the swing escape action, so that all the mechanical energy generated by the swing is applied to the contact interface between the stuck joint module and the interference point, avoiding energy dispersion during the movement. The swing amplitude increases from ±5° to ±20° in 3-4 swing cycles, adopting a gradual impact strategy from light to heavy, avoiding secondary violent impacts between the joint module and the internal components of the transformer due to excessive initial swing amplitude. The 0.5Hz swing frequency corresponds to 2 seconds per swing cycle, which matches the response time of the motor reversal, ensuring precise coupling between the swing action and the reversal pause period. Test data shows that the success rate of getting out of trouble after timing synchronization is about 35% higher than that of the asynchronous state, thus achieving the technical effects of energy concentration, gradual impact, and significant improvement in success rate.

[0023] Furthermore, by installing an encoder on the conveyor wheel, the controller determines the robot's cumulative entry depth based on the encoder's feedback signal and compensates for the attitude angles of each joint using attitude sensors. This solves the technical problems of low accuracy and susceptibility to environmental interference in existing technologies that rely solely on time estimation or indirect motor current to determine entry depth. The principle of this depth measurement method is as follows: The encoder uses an incremental photoelectric encoder with a resolution of 360 pulses / revolution, installed at the conveyor wheel's shaft. The controller calculates the arc length release amount at the wheel's edge by counting pulses and obtains the release length by combining it with the initial zero point position. Since the robot may experience slight bending due to jamming or attitude changes during entry, there is a deviation between the actual entry depth and the release length. The controller has a built-in compensation algorithm that calculates the actual projected length of the robot body in space using forward kinematics based on the attitude angles fed back by the attitude sensors of each joint module, correcting the cumulative entry depth. This achieves the technical effect of direct entry depth measurement, dynamic compensation, and accuracy better than ±2%.

[0024] Furthermore, by having the third control unit compare the accumulated entry depth with the preset entry depth only after the second control unit has completed the escape maneuver, the technical problem of parallel execution of the escape process and depth judgment in existing technologies, which easily leads to control conflicts, is solved. The principle of this timing design is as follows: During the escape maneuver performed by the second control unit, the robot may generate additional backward displacement due to intermittent reversals. If depth comparison is continuously performed during this process, the fluctuation of the depth value may trigger the pre-tension force elimination action, resulting in logical confusion caused by prematurely eliminating the pre-tension force before the escape is completed. Therefore, the controller sets a status flag after the escape maneuver is completed, and the third control unit is only activated to perform depth comparison after this flag is set, thereby achieving the technical effect of functional decoupling, clear timing, and no interference between the two control units.

[0025] Furthermore, by using the third control unit to reverse the transfer wheel by 5-8mm when the robot's cumulative depth of entry reaches 80% of its total length, the preload between the fixed component and the robot's tail is eliminated. This solves the technical problem in existing technologies where the rigid constraint of the tail restricts joint flexibility and affects the accuracy of posture adjustment during deep operations. The principle of this preload elimination is as follows: When the robot is initially wound and retracted, the connection between the fixed component and the tail's movable shaft keeps the body in a tensioned state. As the transfer wheel rotates forward to release the tension, the tail remains connected through the fixed component. This connection generates a continuous preload during travel, causing the tail joint to constantly bear tension, thus limiting its pitch and yaw degrees of freedom. When the cumulative depth of entry reaches 80% of the robot's total length, the robot's head has reached the main working area. At this point, the transfer wheel is reversed by 5-8mm. The reversal stroke is determined based on the gap analysis of the connection structure between the fixed component and the tail's movable shaft, which is sufficient to completely relax the connection. The tail joint thus gains the same degrees of freedom of movement as the head joint, achieving the technical effect of complete release of the tail joint and more flexible posture adjustment during deep operations.

[0026] Furthermore, by using a third control unit to control the reverse linear speed of the conveyor wheel to be 1.2 times the robot's autonomous forward linear speed during robot retrieval, the technical problem of robot accumulation, entanglement, or jamming within the transformer cavity caused by speed mismatch during retrieval in existing technologies is solved. The principle of this speed difference control is as follows: the reverse retrieval of the conveyor wheel and the autonomous backward movement of the robot work in coordination, with the reverse linear speed slightly higher than the autonomous forward speed. This keeps the robot in a slightly tense state throughout the retrieval process, preventing accumulation within the cavity due to improper speed matching (reverse speed lower than autonomous speed) or excessive instantaneous tension between the tail and the fixed components due to excessively high reverse speed (far exceeding the autonomous speed). The 1.2-fold speed difference has been verified in prototype testing as a balance point between retrieval efficiency and structural safety. Typical values ​​are set at a reverse linear speed of 24-36 mm / s and an autonomous forward speed of 20-30 mm / s, thus achieving stable retrieval, no accumulation, and no over-tension.

[0027] Furthermore, by setting a spiral storage groove on the edge of the conveyor wheel, and equipping the groove with rolling elements, the technical problems of mutual compression of joint modules during robot storage and accumulation of frictional resistance during release in the prior art are solved. The principle of this storage structure is as follows: the pitch of the spiral storage groove is set to be equal to the length of a single joint module, so that when the robot body is wound and stored, each joint module is embedded into the groove in sequence, and the distance between adjacent joint modules is maintained uniformly, avoiding mutual compression or bending caused by accumulation; the rolling elements (steel balls or rollers) are evenly distributed along the spiral path of the storage groove, with a spacing of no more than twice the diameter of the robot body, ensuring that at least three rolling elements provide support at any position of the body in the storage groove, converting sliding friction into rolling friction, and reducing the coefficient of friction from 0.3-0.5 for sliding friction to 0.05-0.1 for rolling friction, thereby achieving the technical effects of orderly storage, smooth release, and significantly reduced motor load.

[0028] Furthermore, by installing a clamping roller within the storage slot, and having the third control unit control the clamping roller to clamp the retrieved robot portion with a preset torque of 0.2 N·m after the fixing component detaches from the robot's tail, this solves the technical problem in existing technologies where the robot, lacking constraint, may become loose or vibrate within the transfer wheel after retrieval and accidentally detach. The principle of this clamping constraint is as follows: after the fixing component detaches from the robot's tail, the tail loses its fixed constraint. If the retrieved portion is not effectively constrained at this time, it may become loose or accumulate within the transfer wheel. The clamping roller employs an elastic support structure (such as spring loading), and immediately actuates after the fixing component detaches, clamping the retrieved portion with a constant torque of 0.2 N·m. This torque, determined through testing and calibration, is sufficient to clamp the robot body firmly within the storage slot to prevent detachment, while being far less than the peak output torque of the joint module drive motor (typically 0.8–1.2 N·m), ensuring that the robot can overcome the clamping force and extend smoothly during the next release. The elastic structure of the clamping roller can adapt to the radial dimension changes of the robot body in the storage slot, avoiding damage caused by rigid compression, thus achieving the technical effect of stable storage in non-working state, no loosening under vibration, and unobstructed release next time.

[0029] Furthermore, the wheel-type storage and orderly release of the conveyor mechanism solves the storage and guidance problems before the robot enters; the real-time perception of the robot's motion and force states is solved through the ultra-redundant joint modules and multi-sensor fusion; the accurate differentiation between instantaneous impact and continuous jamming is solved through the three-dimensional jamming judgment logic based on 1.5 times the rated torque + 0.3 seconds duration + ±15° attitude deviation; the energy concentration and progressive impact problems at jamming points are solved through the collaborative escape strategy of intermittent reversal + cycle-by-cycle incremental oscillation and time synchronization; the accurate quantification of entry depth is solved through depth measurement with encoder and attitude compensation; the functional decoupling problem of the control unit is solved through the timing design of triggering depth comparison only after escape is completed; the release of the tail joint's degrees of freedom in deep operations is solved by reversing 5-8mm at the 80% depth threshold to eliminate preload; the stability problem during the recovery process is solved through recovery control with 1.2 times the speed difference; and the orderly storage and frictional resistance problems are solved through the mechanical structure of the spiral storage groove, rolling elements and pressure rollers. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the robot in a non-working state according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the robot's working state according to an embodiment of the present invention; Figure 3 This is a block diagram of the control system structure of the robot according to an embodiment of the present invention; Figure 4 This is a logic block diagram for determining when a robot gets stuck, as shown in an embodiment of the present invention. In the diagram, 1 – motor; 2 – bracket; 3 – conveyor wheel; 4 – belt; 5 – drive shaft; 6 – robot; 7 – head; 8 – exit. Detailed Implementation

[0031] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0032] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0033] It should be noted that in the description of this invention, the terms such as up, down, left, right, inside, and outside indicate the direction or positional relationship based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0034] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Please see Figure 1 - Figure 4 As shown, Figure 1 This is a schematic diagram of the robot in a non-working state according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the robot's working state according to an embodiment of the present invention; Figure 3 This is a block diagram of the control system structure of the robot according to an embodiment of the present invention; Figure 4 A logic block diagram for determining when the robot gets stuck, according to an embodiment of the present invention.

[0036] Example 1 This invention provides a coiled, super-redundant snake robot for internal inspection of oil-immersed transformers, comprising: The conveying mechanism, which is used to drive the robot 6 into the transformer chamber, includes a bracket 2 for mounting the conveyor wheel 3, a motor 1 for driving the conveyor wheel 3 to rotate, and a fixed assembly for connecting to the movable shaft at the tail of the robot 6. Robot 6 is composed of several articulated joint modules that are hinged together in sequence. Each articulation module is equipped with an attitude sensor and a joint torque sensor. When not in operation, Robot 6 is wrapped around and stored on the edge of the conveyor wheel 3. The linkage control system includes a controller, a speed sensor and a torque sensor mounted on the transmission wheel 3, and an attitude sensor and a joint torque sensor electrically connected to the controller respectively. The transfer wheel control module includes a first control unit for determining the initial posture of the robot 6 entering the transformer chamber and the initial rotation speed of the transfer wheel 3 based on path planning at maintenance and inspection points; a second control unit for controlling the transfer wheel 3 to intermittently reverse to provide a return stroke when the robot 6 is stuck, based on the instantaneous torque value and attitude angle deviation of any joint module of the robot 6, and controlling the joint module and its adjacent joint modules to perform a periodic swinging escape action with progressively increasing swing amplitude, so that the swinging escape action and intermittent reversal work together at the stuck position; and a third control unit for stopping the rotation of the transfer wheel 3 when the cumulative entry depth of the robot 6 reaches a preset depth, and simultaneously controlling the transfer wheel 3 to reverse to retract the redundant length to eliminate the preload between the fixed component and the tail of the robot 6, and controlling the transfer wheel 3 to reverse to retract the robot 6 when the robot 6 completes maintenance and inspection.

[0037] In this embodiment of the invention, the drive motor 1 is connected to the drive motor 1 via the belt 4. When the robot 6 is in working state, the head 7 of the robot 6 enters the transformer cavity through the outlet 8.

[0038] Specifically, the second control unit determines that robot 6 is stuck based on the results that the instantaneous torque value fed back by the joint torque sensor is greater than a preset multiple of the rated torque and the duration is greater than a preset time, and the attitude angle deviation fed back by the attitude sensor is greater than a preset angle deviation.

[0039] In this embodiment of the invention, the preset multiplier is 1.5 times, the preset time is 0.3 seconds, and the preset angle deviation is ±15°.

[0040] Specifically, the value of the preset multiple is determined by a combination of the following methods: Mechanical structure strength analysis: Finite element analysis was performed on the structural strength of the joint module to determine the maximum allowable torque within the elastic deformation range. Tests showed that when the torque reaches 1.5 times the rated torque, the joint module remains in the elastic deformation stage and can fully recover after the external force is removed, without causing plastic deformation or structural damage.

[0041] Motor drive capability matching: The drive motor 1 built into the joint module is typically designed to have a peak torque output capability of 1.5 to 2.0 times the rated torque. Setting the preset multiple to 1.5 times ensures that motor 1 has not yet entered the overload protection state when the jamming judgment is triggered, thus reserving sufficient drive margin for subsequent extrication actions.

[0042] It is understandable that the preset multiple represents the threshold of the instantaneous overload capacity that the joint module can withstand. When the instantaneous value fed back by the joint torque sensor is greater than 1.5 times the rated torque, it indicates that the load currently borne by the joint module has significantly exceeded the normal operating range, and it is highly likely that physical interference or jamming has occurred with the external environment. Specifically, the value of the preset time is determined comprehensively through the following methods: System control cycle matching: The typical control cycle of the controller is 20ms (i.e., 50Hz control frequency). 0.3 seconds corresponds to 15 consecutive control cycles, which is sufficient to cover at least two complete sensor sampling and control response cycles, ensuring the reliability of the judgment.

[0043] Statistical analysis of the duration of instantaneous impacts: In an experiment simulating an obstacle inside a transformer, the torque impact waveforms of the robot's 6 joints upon instantaneous contact with the obstacle were collected. Experimental data showed that the duration of the vast majority of instantaneous impacts was less than 0.1 seconds, with a very small number lasting no more than 0.2 seconds. Setting a threshold of 0.3 seconds ensures that all instantaneous impacts are filtered out.

[0044] Response sensitivity balance: If the preset time is too short (e.g., 0.1 seconds), the impact signal may be misinterpreted as jamming; if the preset time is too long (e.g., more than 0.5 seconds), it may cause a response delay when actual jamming occurs, increasing the interaction time between the joint module and the environment, and even causing structural damage. 0.3 seconds is the optimal value for balancing interference resistance and response sensitivity.

[0045] Understandably, the preset time represents the duration threshold of the abnormal torque state, used to filter out instantaneous impact signals. Only when the instantaneous torque value exceeds 1.5 times the rated torque for a duration of 0.3 seconds is the abnormality considered a persistent jamming rather than an occasional contact. The introduction of this parameter essentially creates a time window filter to prevent the robot from being misjudged as stuck due to momentary collisions between the robot and the internal components of the transformer during its movement (such as the edge of the joint module rubbing against the insulating cardboard, or briefly contacting the oil passage wall, etc.), thus triggering unnecessary escape actions.

[0046] Specifically, the preset angle deviation value is determined comprehensively through the following methods: Kinematic simulation of Robot 6: Based on the kinematic model of Robot 6, simulations were performed on typical travel trajectories (such as straight lines and curves with small curvature) to calculate the attitude angle deviation range of each joint module under conditions without external interference. Simulation results show that the attitude angle deviation is usually within ±8° during normal travel, and no greater than ±12° under extreme conditions. Transformer Internal Space Constraint Analysis: A 3D model of a typical transformer's internal structure (such as winding gaps, core windows, and clamping gaps) was created to analyze the maximum allowable attitude deviation when robot 6 moves within it. The analysis shows that when the attitude angle deviation exceeds 15°, the risk of interference between the joint module and the transformer's internal components increases significantly. Actual prototype testing verification: Travel tests were conducted on actual transformers or high-fidelity simulated fixtures, collecting attitude angle deviation data under two conditions: normal passage and jamming. Statistical analysis shows that the 95% confidence interval for attitude angle deviation during normal passage is within ±12°, while the deviation rapidly increases to over ±18° when jamming occurs. Setting ±15° as a threshold allows for triggering a judgment in the early stages of jamming (before structural damage occurs), providing response time for extrication actions.

[0047] Understandably, the preset angle deviation represents the tolerance range of the joint module's attitude angle deviating from the expected value. When the absolute value of the deviation between the attitude angle fed back by the attitude sensor and the expected attitude angle in the planned trajectory is greater than 15°, it indicates that the motion trajectory of the joint module has seriously deviated from the preset path, and it is very likely that it will be unable to follow the command movement due to jamming. This parameter reflects the balance between the robot's 6-joint module's trajectory following capability and posture compliance under normal travel conditions. Under normal travel conditions, due to the robot's flexible structure and environmental uncertainties, the posture angle fluctuates within a certain range; exceeding this range means that the joint module has lost its ability to effectively follow the commanded trajectory.

[0048] Specifically, in response to the robot 6 getting stuck, the second control unit controls the transmission wheel 3 to rotate intermittently, causing the robot 6 to move backward a preset distance and then stop rotating. It also controls the stuck joint module to sequentially transmit periodic swings with progressively increasing amplitudes towards the tail.

[0049] In this embodiment, the preset retraction distance is 10mm-20mm, preferably 15mm.

[0050] Specifically, the value of the preset rollback distance is determined by a combination of the following methods: Matching the retraction stroke with the joint spacing: The spacing between adjacent joint modules of Robot 6 is designed to be 20-30mm. Setting a retraction distance of 10-20mm ensures that a stuck joint module can move away from the interference point after reversing and retracting, while preventing subsequent joint modules from experiencing new posture deviations due to excessive retraction; Redundant design for escape space: In tests simulating the jamming condition inside a transformer, statistics show that when the retraction distance reaches 10mm or more, more than 90% of the jamming points can be freed from physical interference; when the retraction distance reaches 20mm, the release rate increases to over 98%. Further increasing the retraction distance beyond this point has limited effect on improving the escape efficiency and may even prolong the escape time. Reverse response characteristics of motor 1: Servo motor 1 has an acceleration response time during the reverse start-up phase. The 10-20mm retraction distance corresponds to a reverse running time of about 0.2-0.4 seconds for motor 1, which is sufficient to overcome the starting inertia of motor 1, and will not cause excessive reverse pulling force between the tail of robot 6 and the fixed component due to excessive reverse time.

[0051] Understandably, the preset retraction distance represents the backward travel of the robot 6 body after it becomes stuck, achieved by reversing the transmission wheel 3. This backward travel aims to disengage the stuck joint module from the mechanical interference point with the internal components of the transformer, creating space for subsequent swinging escape actions. The intermittent reverse-reverse alternating backward-stop mode introduces a pause period after each reverse backward movement, allowing the joint module to perform swinging escape actions while stationary, avoiding mutual interference between swinging and reversing during continuous motion.

[0052] Specifically, when the second control unit controls the joint module to perform a periodic swinging escape action with a swing amplitude that increases periodically, it synchronizes the swing amplitude increase period of the swinging escape action with the pause period of the intermittent reversal in time, so that the swinging escape action and the intermittent reversal work together to act on the stuck position.

[0053] In this embodiment of the invention, the swing amplitude increases periodically from ±5° to ±20°, with a frequency of 0.5Hz. The swinging escape action is transmitted sequentially from the joint module where the jamming occurs towards the tail.

[0054] Specifically, the values ​​of the swing amplitude increase period and the reversal pause period are determined by a combination of the following methods: Energy Concentration Effect Analysis: During the period when the transfer wheel 3 reverses, moves backward, and pauses, the robot 6 is stationary. Applying a swinging escape motion at this time ensures that all the impact energy generated by the swing is concentrated between the stuck joint module and the interference point, preventing energy dispersion during movement. Experimental data shows that the escape success rate after timing synchronization is approximately 35% higher than that in the asynchronous state. Swing amplitude increment cycle matching: The 0.5Hz oscillation frequency corresponds to each oscillation cycle being 2 seconds. The oscillation amplitude is set to gradually increase from ±5° to ±20° within 3-4 oscillation cycles, so that the escape action gradually increases from gentle probing to strong struggle, avoiding excessive initial oscillation that could cause secondary violent impacts between the joint module and the internal components of the transformer; Optimization of swing transmission direction: The swing is transmitted sequentially from the stuck joint module to the tail, so that the joint module behind the stuck point forms a wave-like motion, and the swing energy is transmitted step by step along the robot body and concentrated at the stuck position, rather than dissipating towards the head.

[0055] Understandably, the timing coordination between the swinging escape maneuver and the intermittent reversal is essentially a mechanism for concentrated energy release. The intermittent reversal first causes the robot's body to move backward, relieving the continuous pressure of the forward propulsion force on the stuck point. During the pause, the swinging amplitude increases periodically, concentrating mechanical energy on the contact interface between the stuck joint module and the interference point, using periodic reciprocating impacts to loosen the stuck point. This precise timing coupling of the two actions enables a phased escape strategy of first retreating, then swinging, and finally probing, effectively improving the success rate of escape.

[0056] Specifically, the conveyor wheel 3 is also equipped with an encoder for detecting the release length of the robot 6, and the controller determines the cumulative entry depth of the robot 6 based on the feedback signal from the encoder.

[0057] In this embodiment of the invention, the encoder is an incremental photoelectric encoder with a resolution of 360 pulses / revolution, which is installed on the shaft of the conveyor wheel 3.

[0058] Specifically, the implementation methods for encoder detection and depth calculation are determined through a combination of the following approaches: Release length to wheel angle conversion: The diameter of the transmission wheel 3 is a fixed value. Each time the encoder detects a certain number of pulse signals, it converts this into the arc length release amount at the wheel edge. This arc length release amount is the release length of the robot 6 body. The controller accumulates the release length in real time and, combined with the initial zero-point position, obtains the cumulative entry depth of the robot 6 head. Zero-point calibration mechanism: In the initial winding and storage state of robot 6, the controller records the current encoder position as the absolute zero point. When the conveyor wheel 3 rotates forward to release, the encoder pulses accumulate; when it rotates in the reverse direction to retract, the pulses decrease, ensuring that the accumulated depth always reflects the actual extension length. Redundant Length Compensation Algorithm: Since robot 6 may experience slight bending due to jamming or posture changes during entry into the transformer chamber, there is a slight deviation between the actual entry depth and the release length. The controller's built-in compensation algorithm, combined with the joint posture angles fed back from the posture sensors, corrects the cumulative entry depth, eliminating length measurement errors caused by the robot's bending.

[0059] Understandably, the introduction of the encoder enables the controller to acquire the cumulative entry depth of robot 6 in real time, providing accurate quantitative data for the depth judgment and preload elimination triggering of the third control unit. Compared to methods that rely solely on time estimation or indirect judgment based on motor 1 current, the encoder-based direct measurement method offers higher accuracy and reliability.

[0060] Specifically, the third control unit responds to the second control unit completing the escape action by comparing the cumulative entry depth with the preset entry depth.

[0061] In this embodiment of the invention, the preset entry depth is 80% of the total length of the robot body 6.

[0062] Specifically, the setting of this triggering logic is determined comprehensively through the following methods: Post-extrication recovery requirements: During the extrication process executed by the second control unit, robot 6 may experience additional backward displacement due to intermittent reversals. Continuing depth comparison during the extrication process could lead to false triggering of the preload release action. Therefore, the comparison should only be performed after extrication is complete to ensure that depth judgment is based on a stable travel state. The depth threshold selection is based on the following: setting the preset entry depth to 80% of the total length of the robot body is based on the statistical analysis of typical locations of maintenance and inspection points inside transformers. In most transformer structures, key components that need to be inspected (such as winding ends, lead wire joints, and clamp fastening points) are usually located in the 70%-90% range of the chamber depth. Setting the 80% threshold ensures that Robot 6 has reached the main working area while also reserving sufficient maneuverability for subsequent forward movement. Anti-false triggering design: Before the escape maneuver is completed, the third control unit is in standby mode and does not process depth information. This logic effectively prevents depth measurement fluctuations caused by changes in the robot's posture during the escape process from being mistakenly judged as reaching the preset depth.

[0063] Understandably, this triggering logic clearly defines the timing relationship between the second and third control units. Only after the escape maneuver is completed is the third control unit activated for a deep comparison, ensuring functional decoupling between the two control units and avoiding control command conflicts during the escape process.

[0064] Specifically, the third control unit controls the transmission wheel 3 to reverse to eliminate the preload between the fixing component and the tail of the robot 6, based on the result that the cumulative entry depth of the robot 6 reaches a preset proportion of its total body length.

[0065] In this embodiment of the invention, the preset ratio is 80%.

[0066] Specifically, the control logic for eliminating preload is determined comprehensively through the following methods: Analysis of the preload generation mechanism: When robot 6 is initially wound and stored on the edge of the conveyor wheel 3, the fixing component is connected to the movable shaft at the tail of robot 6, keeping the robot 6 body in a tensioned state. As the conveyor wheel 3 rotates forward and releases, robot 6 enters the transformer chamber. The tail remains connected to the conveyor wheel 3 through the fixing component. This connection generates a certain preload during the movement of robot 6, limiting the flexibility of the tail joint. Timing for eliminating preload: When the cumulative depth reaches 80% of the total length of the robot body, the head of robot 6 has reached the main working area, but the tail has not yet disengaged from the conveyor wheel 3. At this time, control the conveyor wheel 3 to rotate 5-8mm, so that the connection between the fixed component and the tail of robot 6 changes from a tensioned state to a relaxed state, eliminating the preload and restoring the freedom of the tail joint; Reverse stroke control: In this embodiment of the invention, the reverse stroke corresponds to the robot 6 body retracting 5-8mm. This stroke is determined as follows: based on the gap analysis of the connection structure between the fixed component and the tail movable shaft of the robot 6, a reverse stroke of 5mm-8mm is sufficient to change the connection from a tense state to a completely relaxed state, while preventing the robot 6 head from retracting from the working area due to excessive reverse stroke.

[0067] Understandably, the elimination of preload allows the tail joint of robot 6 to achieve the same degrees of freedom of movement as the head joint, avoiding any impact on the accuracy of overall posture control due to tail tension. During the recovery phase after maintenance and inspection, this relaxed state also facilitates the smooth recovery of robot 6 by the transfer wheel 3.

[0068] Specifically, the third control unit responds to the command of the recovery robot 6 and controls the reverse linear speed of the transfer wheel 3 to be greater than the linear speed of the robot 6's autonomous forward movement.

[0069] In this embodiment of the invention, the reversal linear velocity is 1.2 times the autonomous forward linear velocity of robot 6.

[0070] Specifically, the speed difference value is determined by a combination of the following methods: Recovery efficiency optimization: The reverse linear speed of the conveyor wheel 3 is greater than the autonomous forward linear speed of the robot 6, so that the robot 6 body is always in a slightly tense state during the recovery process, avoiding the accumulation or entanglement of the body in the transformer chamber due to improper speed matching; Autonomous forward speed calibration: The autonomous forward speed of Robot 6 under flat working conditions is determined by the drive frequency of the joint modules, with a typical value of 20-30 mm / s. The reverse linear velocity is set to 1.2 times the autonomous forward speed, i.e., 24-36 mm / s, to ensure that the recovery speed is slightly higher than the forward speed, forming stable recovery tension. Overspeed protection mechanism: The speed difference should not be too large, otherwise it may cause excessive instantaneous tension between the tail of robot 6 and the fixed component, resulting in damage to the joint module or connection structure. A speed difference of 1.2 times has been verified in prototype tests as the optimal value for balancing recovery efficiency and structural safety.

[0071] Understandably, this speed control strategy enables the coordinated action of the active retraction of the transfer wheel 3 and the autonomous backward movement of the robot 6. After completing maintenance and inspection, the robot 6 can autonomously move towards the tail, while the transfer wheel 3 actively retracts its main body at a slightly higher linear speed. The two work together to achieve efficient and stable recovery of the robot 6.

[0072] Specifically, the edge of the conveyor wheel 3 is provided with a spiral storage groove for storing the robot 6, and the storage groove is provided with rolling elements to reduce frictional resistance.

[0073] In this embodiment of the invention, the pitch of the spiral storage groove is matched with the length of the robot's 6-joint module, and the rolling element is made of steel balls or rollers, which are embedded in the inner wall of the storage groove.

[0074] Specifically, the structural design of the spiral receiving groove and the rolling element is determined through a combination of the following methods: Storage matching design: The pitch of the spiral storage groove is set to be equal to the length of a single joint module, ensuring that when the robot body is wound and stored, each joint module is embedded into the groove in sequence, and the distance between adjacent joint modules is kept uniform, avoiding mutual compression or bending caused by stacking.

[0075] Frictional Resistance Analysis: During the winding, storage, and release process, the robot body generates sliding friction with the inner wall of the storage groove. Traditional sliding friction methods result in significant accumulated frictional resistance when the storage length is long, potentially affecting the smoothness of release. The introduction of rolling elements transforms sliding friction into rolling friction, significantly reducing the coefficient of friction.

[0076] Rolling element layout: The rolling elements are evenly distributed along the spiral path of the storage groove, with a spacing of no more than twice the diameter of the robot body. This ensures that when the robot body moves at any position in the storage groove, at least three rolling elements provide support at the same time, thus guaranteeing the stability of the movement.

[0077] Understandably, the spiral storage groove enables the robot 6 to be compactly stored when not in operation, saving the overall size of the conveying mechanism; the setting of the rolling element significantly reduces the frictional resistance during storage and release, reduces the load on the motor 1, and improves the energy efficiency and motion stability of the system.

[0078] Specifically, the storage slot is also equipped with a clamping roller. After the control fixing component disengages from the tail of the robot 6, the third control unit controls the clamping roller to clamp the retrieved part of the robot 6 with a preset torque. In this embodiment of the invention, the preset torque is 0.2 N·m.

[0079] Specifically, the setting and control of the pressure rollers are determined comprehensively through the following methods: The clamping torque selection criteria: The clamping torque of 0.2 N·m was determined through test calibration. This torque is sufficient to clamp the robot body 6 into the storage slot to prevent the body from loosening due to vibration or external force. At the same time, this torque is much less than the drive output capability of the robot 6 joint module, ensuring that the robot 6 can overcome the clamping force and extend smoothly during subsequent release, without causing release difficulties due to excessive clamping.

[0080] Clamping Timing Control: After the fixing component detaches from the tail of robot 6, the tail of robot 6 loses its fixed constraint. At this time, if the recovered part of robot 6 is not effectively constrained, it may become loose or piled up in the transfer wheel 3. The clamping rollers act immediately after the tail detaches to apply clamping force to the recovered part, ensuring a stable storage state.

[0081] Pressure roller structure design: The pressure roller adopts an elastic support structure (such as spring loading), which can adapt to the radial dimension changes of the robot body in the storage slot, and avoids rigid compression damage to the body while maintaining a constant pressure torque.

[0082] Example 2 This embodiment provides an autonomous escape control process for a coiled, super-redundant snake robot used for internal inspection of oil-immersed transformers when it gets stuck during the process of entering the transformer chamber.

[0083] As robot 6 is released via conveyor wheel 3 and enters the transformer chamber, the controller collects feedback data from the attitude sensors and joint torque sensors built into each joint module in real time. The rated torque of the joint module is set to 0.5 N·m, the preset multiple is 1.5 times, that is, the instantaneous torque value is greater than 0.75 N·m; the preset time is 0.3 seconds; and the attitude angle deviation threshold is ±15°.

[0084] When the fourth joint module of robot 6 interferes with the internal windings of the transformer during movement, the instantaneous torque value reported by the joint torque sensor rises to 0.82 N·m and lasts for 0.35 seconds. At the same time, the attitude sensor reports that the pitch angle deviation of the joint module reaches -18°. The controller determines that this state meets the jamming condition and triggers the second control unit to execute the escape procedure.

[0085] The second control unit first controls the transmission wheel 3 to intermittently reverse, moving backward 15mm before stopping. Then, it controls the fourth joint module and its adjacent third and fifth joint modules to sequentially transmit periodic oscillations with progressively increasing amplitudes, starting from the fourth joint module and moving towards the tail. The amplitude increases periodically from ±5° to ±20°, with an oscillation frequency of 0.5Hz. The amplitude increase period is synchronized with the pause period after the transmission wheel 3 reverses. After three oscillation cycles, the joint module successfully disengages from the interference point, the attitude angle deviation returns to within ±8°, and the torque value drops to 0.55 N·m. The controller determines that the escape from the obstacle has been successful and resumes forward movement.

[0086] This embodiment verifies the effectiveness of the three-dimensional stuck judgment logic based on 1.5 times the rated torque, 0.3 seconds duration and ±15° attitude angle deviation, as well as the coordinated escape capability of intermittent reversal and cycle-by-cycle incremental oscillation under time synchronization.

[0087] Example 3 This embodiment provides a control process for eliminating and recovering preload when the cumulative entry depth of a coiled, super-redundant snake robot used for internal inspection of oil-immersed transformers reaches a preset threshold.

[0088] The robot 6 has a total length of 1200mm, and the preset entry depth threshold is set to 80% of the total body length, i.e., 960mm. The transfer wheel 3 is equipped with an incremental photoelectric encoder with a resolution of 360 pulses / revolution. The controller calculates the release length by counting pulses and performs kinematic compensation by combining the attitude angles fed back by the attitude sensors of each joint module, and calculates the cumulative entry depth in real time.

[0089] When the cumulative depth reaches 965mm, the controller determines that the preload elimination condition is met. The third control unit then controls the transmission wheel 3 to rotate 6mm in reverse, changing the connection between the fixed component and the tail movable axis of the robot 6 from a tensioned state to a relaxed state, thus eliminating the tail preload. At this point, the tail joint of the robot 6 gains the same degrees of freedom as the head joint, significantly improving the flexibility of posture adjustment.

[0090] After maintenance and inspection are completed, the controller receives a recovery command. The third control unit controls the conveyor wheel 3 to recover the robot at a reverse linear speed of 30 mm / s. Simultaneously, the robot 6 moves autonomously towards the tail at a forward speed of 25 mm / s. The ratio of the reverse linear speed to the autonomous forward speed is 1.2:1. During the recovery process, the robot 6 remains under slight tension to prevent accumulation or entanglement.

[0091] As the tail of robot 6 approaches the conveyor wheel 3, the fixing component disengages from the tail shaft, and the third control unit controls the clamping rollers in the storage groove to clamp the recovered portion with a preset torque of 0.2 N·m. Robot 6 is finally completely wrapped and stored in the spiral storage groove on the edge of the conveyor wheel 3. The rolling elements embedded in the storage groove convert sliding friction into rolling friction, ensuring smooth and jam-free storage.

[0092] This embodiment verifies the rationality of eliminating the preload at the 80% depth threshold, and the balancing effect of the 1.2 times speed difference recovery control strategy between smooth recovery and structural safety.

[0093] Understandably, the clamping rollers and the fixing components form a complementary constraint mechanism. During the release phase of robot 6, the fixing components provide tail constraint, and the clamping rollers are in the released state; after retrieval is completed, the fixing components disengage, and the clamping rollers take over to provide clamping constraint, ensuring stable storage of robot 6 in non-working states and preventing accidental loosening due to vibration or handling.

[0094] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A coiled, super-redundant snake-like robot for internal inspection of oil-immersed transformers, characterized in that, include: A conveying mechanism for driving the robot into the transformer chamber includes a support, a conveyor turntable, a motor, and a fixed assembly connected to the robot's tail shaft. Each joint module of the robot is equipped with an attitude sensor and a joint torque sensor. A linkage control system includes a controller, a speed sensor and a torque sensor mounted on the conveyor turntable, and the attitude sensor and the joint torque sensor electrically connected to the controller. The transfer wheel control module includes a first control unit for determining the initial posture of the robot entering the transformer chamber and the initial rotation speed of the transfer wheel based on path planning of maintenance and inspection points; and a second control unit for controlling the transfer wheel to intermittently reverse to provide a return stroke when the robot is stuck, based on the instantaneous torque value and attitude angle deviation of any joint module of the robot, and controlling the joint module and its adjacent joint modules to perform a periodic swinging escape action with progressively increasing swing amplitude, so that the swinging escape action and the intermittent reversal work together at the stuck position.

2. The robot according to claim 1, characterized in that, The second control unit determines that the robot is stuck based on the results that the instantaneous torque value fed back by the joint torque sensor is greater than a preset multiple of the rated torque and the duration is greater than a preset time, and the attitude angle deviation fed back by the attitude sensor is greater than a preset angle deviation.

3. The robot according to claim 2, characterized in that, In response to the robot getting stuck, the second control unit controls the transmission wheel to rotate intermittently, causing the robot to retreat a preset distance and then stop rotating. It also controls the stuck joint module to sequentially transmit periodic swings with progressively increasing amplitudes towards the tail.

4. The robot according to claim 3, characterized in that, When the second control unit controls the joint module to perform a periodic swinging escape action with a progressively increasing swing amplitude, it synchronizes the swing amplitude increase period of the swinging escape action with the pause period of the intermittent reversal in time, so that the swinging escape action and the intermittent reversal work together to act on the stuck position.

5. The robot according to claim 1, characterized in that, The conveyor wheel is also equipped with an encoder for detecting the robot's release length, and the controller determines the robot's cumulative entry depth based on the feedback signal from the encoder.

6. The robot according to claim 1, characterized in that, The linkage control unit also includes a third control unit, which is used to stop the rotation of the conveyor wheel when the cumulative entry depth of the robot reaches a preset depth, and synchronously control the conveyor wheel to reverse to retract the redundant length so as to eliminate the preload between the fixing component and the tail of the robot, and control the conveyor wheel to reverse to retract the robot when the robot completes maintenance and inspection.

7. The robot according to claim 6, characterized in that, The third control unit controls the transmission wheel to reverse to eliminate the pre-tension force between the fixing component and the robot's tail, based on the result that the robot's cumulative entry depth reaches a preset proportion of its total body length. The third control unit responds to the second control unit completing the escape action by comparing the cumulative entry depth with the preset entry depth.

8. The robot according to claim 6, characterized in that, The third control unit responds to the instructions of the retrieval robot by controlling the reverse linear speed of the conveyor wheel to be greater than the linear speed of the robot's autonomous forward movement.

9. The robot according to claim 1, characterized in that, The edge of the conveyor wheel is provided with a spiral storage groove for storing the robot, and the storage groove is provided with rolling elements to reduce frictional resistance.

10. The robot according to claim 9, characterized in that, The storage slot is also equipped with a clamping roller. After the third control unit controls the fixing component to detach from the robot tail, it controls the clamping roller to clamp the recovered robot part with a preset torque.

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