Handheld self-walking welding gun with anti-overturning function

Abstract

The application relates to a handheld self-walking welding gun with an anti-overturning function, and belongs to the technical field of gas shielded welding equipment. When the self-walking welding gun is welded to the end of a workpiece, the walking wheels gradually separate from the surface of the workpiece, the front end of the welding gun swings, and the forming quality of the end weld deteriorates. The device is electrically connected with a control circuit and a speed reduction driving motor, and is provided with a rotating speed detection end for detecting the rotating speeds of two output half shafts; the rotating speed values of the two output half shafts are read and the rotating speed change amounts of the output half shafts are respectively calculated; when the rotating speed of any output half shaft continuously increases for three sampling periods and the absolute value of the increasing amount increases period by period, it is determined that the load of the corresponding walking wheel continuously decreases, a reverse speed regulation instruction, in which the rotating speed of the speed reduction driving motor first increases and then decreases, is output, and the other walking wheel rotates at a speed of acceleration and then deceleration. The device is used for inhibiting the swinging of the front end of the welding gun at the critical moment when the walking wheels are about to separate from the surface of the workpiece, and improving the forming quality of the end weld.

Description

Technical Field

[0001] This invention relates to the field of gas shielded welding equipment technology, and more specifically, to a handheld self-propelled welding torch with anti-tipping function. Background Technology

[0002] Handheld gas-shielded welding torches are widely used in shipbuilding, engineering machinery, steel structure manufacturing, and pressure vessel industries due to their flexibility and adaptability. This process involves the operator holding the torch, relying on a shielding gas to isolate the welding zone from active components in the air, preventing metal oxidation and nitriding. In current manual operation, welding quality is highly dependent on the operator's skill level, and welding speed is entirely determined by the operator's arm movement speed. Fluctuations in movement speed directly lead to variations in the amount of metal deposited per unit length, resulting in uneven weld reinforcement and penetration along the weld length. Prolonged holding of the torch in the air can also cause hand fatigue and tremors, causing the weld center to deviate from the groove center.

[0003] To reduce the difficulty of manual welding and improve the consistency of welding quality, existing technologies include solutions that incorporate a walking mechanism on a handheld welding torch. Chinese patent document CN115533383A discloses a handheld oscillating welding torch, comprising a torch body, an oscillator, a handle, and a walking mechanism. The torch body is oscillatingly mounted on the oscillator, and the walking mechanism is located on the outer surface of the oscillator. The walking mechanism includes a connecting frame connected to the outer surface of the oscillator and a tracking wheel rotatably mounted on the connecting frame. The walking mechanism may also include an automatic walking motor mounted on the connecting frame, which is connected to the tracking wheel via a transmission mechanism. This solution tracks the weld position through the walking mechanism, reducing the difficulty of welding operations to some extent. However, the walking wheel in this solution is only used for tracking the weld position. Although the walking mechanism can be equipped with an automatic walking motor, no technical solution is provided for dynamically adjusting the drive motor according to the torch's movement. The operator still needs to manually control the torch's movement speed along the weld direction, and the problem of welding speed uniformity remains unresolved.

[0004] Furthermore, existing technologies also include solutions that mount the welding torch on an independent walking device. Chinese patent document CN118875577A discloses an automatic walking device for a welding torch, including a base, a drive assembly, a transmission assembly, a moving wheel assembly, and a swing arm. The drive assembly includes a fixed frame and a motor, with the motor housed in a receiving slot within the fixed frame. The transmission assembly is connected to both the motor and the moving wheel assembly. This solution mounts the handheld welding torch on an independent automatic walking device, which drives the torch to achieve a uniform welding speed. However, this device itself is an external device independent of the welding torch; the torch needs to be mounted on this device to achieve automatic movement. The device is relatively large, making it difficult to widely apply in space-constrained environments or where workpiece shapes vary, such as inside ship hull sections, on steel structure sites, or during maintenance work. Additionally, the relative position between the walking wheels and the welding torch's gas shielding nozzle is determined by the device's structural dimensions. When the device reaches the end of the workpiece, the walking wheels may detach from the workpiece surface before the gas shielding nozzle, but this document does not offer any solutions to this problem.

[0005] While welding carriages with guide rails or welding robots can achieve precise, uniform movement, they require pre-laying of guide rails, workpiece positioning, and teaching. The equipment is bulky and has a long preparation cycle, making it difficult to widely apply in situations with limited space or varied workpiece shapes. Therefore, maintaining the portability and usability of handheld welding torches while achieving stable self-propelled movement, and resolving issues such as the pitching and wobbling of the torch caused by the travel wheels detaching from the workpiece surface before the gas shielded nozzle when the torch reaches the workpiece end, as well as the differential speed adaptation of the travel wheels when moving on curved weld seams, remain pressing technical challenges in this field. Summary of the Invention

[0006] One objective of this invention is to solve the following problems: how to enable a welding torch to achieve stable self-propelled capability while maintaining its portability and usability, and to solve the problem of pitch and sway of the welding torch caused by the traveling wheel detaching from the workpiece surface before the gas protection nozzle when the welding torch reaches the end of the workpiece, as well as the problem of differential speed adaptation when the traveling wheel travels on curved weld seams.

[0007] To achieve the above objectives, the present invention provides a handheld self-propelled welding torch with anti-tipping function, comprising a welding torch body, a gas protection nozzle at the front end of the welding torch body, a reduction drive motor and a miniature planetary differential disposed inside the welding torch body, the reduction drive motor being drivenly connected to the power input shaft of the miniature planetary differential, and a traveling wheel being connected to each of the two output half-shafts of the miniature planetary differential, the two traveling wheels being used to support the workpiece surface and drive the welding torch body to move, characterized in that:

[0008] The welding torch body also includes a control circuit, which is electrically connected to the reduction drive motor. The control circuit is equipped with a speed detection terminal for detecting the speeds of the two output half-shafts. The control circuit is configured to read the speed values ​​of the two output half-shafts in each sampling period and calculate the speed change of each output half-shaft in the current sampling period relative to the previous sampling period. When the speed of any output half-shaft increases continuously for three consecutive sampling periods, and the absolute value of the increment in each of the three sampling periods increases sequentially, the control circuit determines that the load on the corresponding traveling wheel of that output half-shaft is continuously decreasing and records the orientation of the traveling wheel. In the sampling period following the determination, it outputs a reverse speed adjustment command to the reduction drive motor, causing the speed of the reduction drive motor to first increase and then decrease, thereby causing the other traveling wheel to accelerate and then decelerate. The duration of the reverse speed adjustment command does not exceed the time required for one complete rotation of a single traveling wheel.

[0009] Preferably, the control circuit further includes a differential speed determination module. This module acquires the speed difference signal between the two output half-shafts and compares it with a preset normal differential speed reference range. When the speed difference signal exceeds the normal differential speed reference range, the module determines the direction of the speed difference signal and compares it with the orientation of the continuously decreasing load wheel. If the direction of the speed difference signal and the orientation of the continuously decreasing load wheel are on the same side, the speed difference signal is determined to be an abnormal increase in speed caused by a change in unsupported state, and no compensation action is triggered. If the direction of the speed difference signal and the orientation of the continuously decreasing load wheel are on the same side, the speed difference signal is determined to be an abnormal increase in speed caused by a change in unsupported state, and no compensation action is triggered. If the lowered travel wheels are located on different sides, the speed difference signal is determined to be caused by lateral slippage of the travel wheels. In the next sampling period, the differential speed determination module superimposes a difference compensation signal based on the base speed command. This difference compensation signal causes the target speed of the output half-shaft on the lower speed side to gradually increase at a preset gradual rate, while simultaneously causing the target speed of the output half-shaft on the higher speed side to gradually decrease at the same gradual rate, until the speed difference signal falls back to the normal differential speed reference range. The determination of continuous load reduction and the determination of lateral slippage are executed sequentially in the same sampling period, with the determination of continuous load reduction executed first and the determination of lateral slippage executed later.

[0010] Preferably, the control circuit further includes a start control terminal, which is connected to the output voltage detection circuit of the welding power supply. The output voltage detection circuit monitors the output voltage value of the main circuit of the welding power supply in real time and generates a corresponding voltage detection signal. The control circuit is configured to keep the start circuit disconnected before the start circuit of the geared drive motor is turned on, when the output voltage of the welding power supply is lower than a preset threshold. When the output voltage of the welding power supply reaches the preset threshold and remains stable for more than a first preset duration, the control circuit continues to monitor whether the output voltage of the welding power supply drops to the arc voltage range. When it is detected that the output voltage of the welding power supply drops from the no-load voltage range to the arc voltage range and remains stable for more than a second preset duration, the control circuit turns on the start circuit of the geared drive motor. The start circuit operates independently in parallel with the speed regulator of the geared drive motor, and the control circuit keeps the start circuit on during the duration of the reverse speed regulation command.

[0011] Preferably, a cold wire feeding tube is fixed on the welding torch body, and a wire feeding nozzle is connected to the wire outlet end of the cold wire feeding tube. The welding torch body is also equipped with a wire feeding speed linkage modulation module. This module uses the real-time rotational speed signal of the reduction drive motor as an input variable, multiplies the real-time rotational speed signal by a preset wire feeding speed matching coefficient to generate a target wire feeding speed command value, and outputs it to the speed control terminal of the external cold wire feeder, ensuring that the cold wire feeding speed and the welding torch travel speed maintain a constant proportional relationship. The wire feeding speed linkage modulation module is also connected to the control circuit to receive the output of the control circuit. When the control circuit determines that the load is continuously decreasing and outputs the reverse speed adjustment command, the wire feeding speed linkage modulation module superimposes a transient wire feeding speed compensation amount on the basic linkage value. The direction of this compensation amount is opposite to the direction of the change in the height of the gas protection nozzle caused by the reverse speed adjustment command. That is, when the reverse speed adjustment command reduces the distance between the gas protection nozzle and the workpiece surface, the wire feeding speed decreases based on the basic linkage value. After the compensation is completed, it returns to the basic linkage value. This compensation amount and the reverse speed adjustment command are triggered simultaneously by the same timer channel, have the same duration, and end simultaneously.

[0012] Preferably, the control circuit further includes a three-stage filtering module for the rotational speed signal. This module is divided into a front-end stabilization window, a middle-end discrimination window, and a back-end confirmation window in the time domain. Within the front-end stabilization window, the control circuit acquires rotational speed data from the two output half-shafts and calculates the fundamental rotational speed value and the background noise amplitude. The rotational speed signal is only allowed to enter the middle-end discrimination window if the instantaneous rotational speed deviates from the fundamental rotational speed value by more than three times the background noise amplitude and the duration is greater than one sampling period. Within the middle-end discrimination window, the control circuit calculates the rotational speed change of the signal relative to the previous sampling period. The signal is determined as a sign of reduced effective load and output to the back-end confirmation window only when the rotational speed increases for three consecutive sampling cycles and the absolute value of the increment increases periodically. Within the back-end confirmation window, the control circuit cross-verifies the signal with the load status of the same output half-shaft in the previous sampling cycle. If the rotational speed of the corresponding wheel in the previous cycle is already increasing, the determination is cancelled; if the rotational speed of the corresponding wheel in the previous cycle is stable, the reverse speed adjustment command is confirmed. The total processing time of the three-stage screening module does not exceed one-quarter of the rotational cycle of a single wheel.

[0013] Preferably, the differential speed determination module further includes a gain adjustment submodule. This submodule calculates the first derivative of the speed difference between the two output half-shafts in real time. When the first derivative of the speed difference exceeds a preset acceleration threshold and continues to increase, it determines that the current difference compensation is in an acceleration phase and automatically reduces the gain coefficient of the difference compensation signal by a first proportion. When the first derivative of the speed difference is lower than the preset acceleration threshold or begins to decrease, the gain coefficient is gradually restored to its base value. The gain adjustment submodule also includes an oscillation counter. When it detects that the speed difference signal undergoes alternating positive and negative changes at a frequency not lower than a preset frequency within a preset time window, it determines that the system has entered an oscillation state and reduces the gain coefficient of the difference compensation signal by a second proportion. Simultaneously, it superimposes a damping signal with the same frequency but opposite phase to the oscillation frequency onto the output command of the reduction drive motor. This process continues until the oscillation counter records that the alternating positive and negative frequency has decreased below the preset frequency for three consecutive oscillation cycles, at which point the gain coefficient is gradually restored to its base value. The first proportion is greater than the second proportion, and the amplitude of the damping signal decreases synchronously with the decrease in oscillation amplitude.

[0014] Preferably, the control circuit further includes an arc extinguishing and re-ignition state discrimination module. When the output voltage of the welding power supply rises from the arc voltage range to the open-circuit voltage and the duration exceeds the first threshold, the control circuit determines that the arc has been extinguished and immediately disconnects the starting circuit of the deceleration drive motor. At the same time, it starts a locking timer and locks the conduction function of the starting circuit until the locking timer returns to zero. If the output voltage of the welding power supply drops back to the arc voltage range during the locking timer's timing, the control circuit calculates the time interval between the time of the drop and the time of arc extinguishing. If the time interval is less than the second threshold, it is determined to be a re-ignition after instantaneous arc extinguishing and the locking state of the starting circuit is maintained. If the time interval is greater than or equal to the second threshold, it is determined to be a re-ignition and the locking is released. The delayed conduction logic of the starting circuit is re-executed according to the second preset duration. The values ​​of the first threshold and the second threshold are both based on the period of the welding power supply output ripple, and the second threshold is greater than the first threshold.

[0015] Preferably, the wire feeding speed linkage modulation module further includes a feedback deviation discrimination submodule. This submodule monitors in real time the deviation between the actual wire feeding speed feedback value of the external cold wire feeder and the target wire feeding speed command value output by the wire feeding speed linkage modulation module. When the absolute value of this deviation exceeds a preset deviation threshold and the duration exceeds a preset time window, it determines that the current wire feeding speed linkage has failed and forcibly switches the wire feeding speed to an open-loop holding mode. In this open-loop holding mode, the wire feeding speed is decoupled from the real-time speed signal of the reduction drive motor, and the wire feeding speed is adjusted according to a preset safety setting. The yarn is continuously fed at a constant speed. Simultaneously, the feedback deviation discrimination submodule starts a backtracking timer to backtrack and read the median value of the yarn feeding speed during a period three times the duration of the reverse speed adjustment command in the yarn feeding speed history at the time the reverse speed adjustment command is triggered. This median value is then used as a replacement yarn feeding speed command and output to the external cold yarn feeder. The feedback deviation discrimination submodule exits the open-loop holding mode and resumes normal operation of the yarn feeding speed linkage modulation module after the absolute value of the deviation falls back to within the preset deviation threshold and remains stable for more than the preset time window.

[0016] Preferably, the control circuit is equipped with a high-frequency time base signal source. The frequency of the high-frequency time base signal source is an integer multiple of the frequency corresponding to the highest speed of the reduction drive motor and is not less than 1000Hz. The determination of continuous load reduction, the linkage modulation of wire feeding speed, the determination of lateral slippage, and the conduction control of the start-up circuit share the high-frequency time base signal source and occupy time slot resources in a time-division multiplexing manner according to priority. The priority order is as follows: the determination of continuous load reduction occupies the first time slot, the linkage modulation of wire feeding speed occupies the second time slot, the determination of lateral slippage occupies the third time slot, and the conduction control of the start-up circuit occupies the fourth time slot. When the instructions output by two determinations in the same sampling period act on the same execution component, the control circuit executes the high-priority instruction in priority order and caches the low-priority instruction to be executed in the next sampling period. A status register is also provided between each determination. The status register latches the output status of each determination at the beginning of each sampling period and synchronizes the latched value to all determinations, so that each determination performs calculations based on the same set of status data in the same sampling period.

[0017] Preferably, the control circuit is further provided with a repetitive triggering suppression module. When the control circuit continuously detects that the same traveling wheel experiences a continuous decrease in load and triggers the reverse speed adjustment command in three consecutive unit travel segments, and the time for the output half-shaft speed of the traveling wheel to recover to a stable value after each reverse speed adjustment command is greater than a preset time threshold, the control circuit determines that there are continuous depressions or obstacles on the surface of the current workpiece. At this time, the repetitive triggering suppression module terminates the triggering of subsequent reverse speed adjustment commands and switches the output command of the reduction drive motor to the slow mode. The travel speed in the slow mode is 30% of the normal welding speed, and the speed difference between the two output half-shafts of the micro planetary differential is forcibly locked to zero. At the same time, an alarm signal is issued through the indicator light on the welding torch body. The length of the unit travel segment is equal to the circumference of the traveling wheel rolling one revolution after ground contact. When the operator switches the mode selection switch on the welding torch body to the stop position and then switches it back to the travel position, the repetitive triggering suppression module resets and restores the normal triggering function of the reverse speed adjustment command.

[0018] The present invention has at least the following beneficial effects:

[0019] This invention detects and determines the load status of the traveling wheels in real time. At the critical moment when the traveling wheels are about to detach from the workpiece surface, a reverse speed control command is output to the reduction drive motor, causing the motor speed to first increase and then decrease. This speed change is transmitted to the power input shaft of the miniature planetary differential via a transmission coupling and a universal joint, and then distributed to the two output half-shafts by the miniature planetary differential. The traveling wheels, still grounded, experience instantaneous acceleration and deceleration during this process. During the acceleration phase, an additional driving force is generated at the ground point, pointing towards the workpiece surface. This additional driving force forms a torque relative to the center of mass of the welding torch body, opposite to the pitch direction, thus providing upward support at the critical moment when the welding torch tip begins to sink. The structural characteristics of the miniature planetary differential allow the two output half-shafts to rotate at different speeds, ensuring that the reduced load traveling wheels do not decisively affect the welding torch posture, while the instantaneous acceleration effect of the grounded traveling wheels is concentrated on posture suppression. The duration of the reverse speed adjustment command does not exceed the time it takes for a single traveling wheel to complete one revolution. This ensures that the adjustment is completed within the time window before the traveling wheel completes a full revolution, avoiding unpredictable cumulative effects caused by the speed adjustment action spanning multiple rotational cycles. The method based on the speed change trend utilizes the physical law that the frictional load gradually decreases during the traveling wheel disengagement process. By using the increasing trend of three consecutive sampling cycles, the direction of load change is determined, which helps to obtain the precursor signal of support loss before the traveling wheel completely disengages, providing a time margin for attitude adjustment. This method helps to reduce the pitch of the welding torch tip in areas where the traveling wheel support conditions change, such as at the workpiece end, thereby contributing to improved weld formation quality at the end.

[0020] The differential speed determination module in the control circuit acquires the speed difference signal between the two output half-shafts and compares it with the normal differential speed reference range to distinguish the consistency between the direction of the speed difference signal and the orientation of the traveling wheel as the load continuously decreases. When the direction of the speed difference is the same as the orientation of the load decrease, the speed increase is caused by the change in support condition rather than the differential speed required for actual cornering, and no compensation action is triggered. When the two directions are different, it indicates that the traveling wheel on the side with the higher speed has laterally slipped relative to the workpiece surface. At this time, the differential compensation signal is superimposed on the base speed command as a reference, so that the target speeds of the output half-shafts on the lower and higher speed sides are adjusted towards each other at the same gradual rate until the speed difference falls back to the reference range. The sequential arrangement of executing the load determination first and then the slip determination within the same sampling period allows the slip determination to directly use the result of the load determination as an input condition, which helps to avoid misjudging the speed increase caused by support changes as cornering differential speed or slip, thereby improving the accuracy of differential speed compensation action.

[0021] The start-up control terminal, connected to the welding power supply output voltage detection circuit, sequentially determines the two stages of no-load voltage establishment and arc voltage drop before the start-up circuit of the reduction drive motor is turned on. It then sets a first preset duration and a second preset duration for filtering and confirmation, ensuring that the start-up circuit only turns on after the arc has been stably ignited. The start-up circuit operates independently in parallel with the speed controller. After the start-up circuit is turned on, its on / off state is controlled by the arc interruption and re-ignition state discrimination module, rather than directly by the instantaneous value of the output voltage. Maintaining the start-up circuit on during the execution of the reverse speed regulation command helps reduce the possibility of unexpected interruption of the travel drive due to instantaneous voltage fluctuations during normal welding. It also helps reduce the risk of premature rolling of the travel wheels causing arc ignition point deviation in no-load conditions or when arc ignition fails.

[0022] The wire feed speed linkage modulation module uses the real-time rotational speed of the geared drive motor as the input variable. It converts the output half-shaft speed into the welding torch travel speed, multiplies it by the wire feed speed matching coefficient to generate the target wire feed speed command value, and outputs it to the external wire feeder. This ensures that the cold wire feed speed changes synchronously with the welding torch travel speed, helping to reduce the impact of travel speed fluctuations on the amount of welded metal per unit length. When the load continuously decreases and a reverse speed adjustment command is triggered, the wire feed speed linkage modulation module superimposes a transient compensation amount on the basic linkage value. The direction of this compensation amount is opposite to the direction of the gas shielded nozzle height change caused by the reverse speed adjustment command. That is, when the reverse speed adjustment command causes the grounding travel wheel to accelerate downwards, reducing the distance between the gas shielded nozzle and the workpiece surface, the wire feed speed decreases synchronously from the basic linkage value. After compensation, it returns to the basic linkage value. This compensation amount and the reverse speed adjustment command are triggered and terminated simultaneously through the same channel, helping to maintain the relative distance between the cold wire outlet and the workpiece surface during the reverse speed adjustment action, reducing the possibility of wire extension fluctuations caused by instantaneous changes in the gas shielded nozzle height.

[0023] The three-stage filtering module calculates the fundamental rotational speed and background noise amplitude through a front-end stabilization window. Only signals whose instantaneous rotational speed deviates from the fundamental speed by more than three times the background noise amplitude and whose duration is longer than one sampling period are allowed to enter the middle discrimination window. The middle discrimination window further checks whether the rotational speed meets the trend condition of increasing for three consecutive sampling periods with the absolute value of the increment increasing period by period. Only if this condition is met can the signal enter the back-end confirmation window. The back-end confirmation window cross-validates the signal with the load state of the same output half-shaft in the previous period. Only when the corresponding walking wheel speed in the previous period is in a stable state is the reverse speed regulation command confirmed. The three windows progressively filter the signal, and the total processing time does not exceed one-quarter of the rotational cycle of a single walking wheel. This helps to reduce the probability of malfunctions caused by instantaneous noise interference and repeated triggering while ensuring response speed.

[0024] The gain adjustment submodule in the differential speed determination module calculates the first derivative of the speed difference in real time. When the first derivative exceeds a preset acceleration threshold and continues to increase, it determines that the differential compensation is in the acceleration phase and reduces the gain coefficient by a first proportion. This helps to reduce the gain in advance when the compensation amount increases rapidly to avoid overshoot. When the first derivative is below the threshold or begins to decrease, the gain coefficient is gradually restored to the base value, which helps to maintain an appropriate response speed when the compensation enters the deceleration pullback phase. When the oscillation counter detects that the speed difference signal alternates between positive and negative at a frequency not lower than a preset frequency within a preset time window, it determines that the system has entered an oscillation state and reduces the gain coefficient by a second proportion. At the same time, it outputs a damping signal with the same frequency and opposite phase as the oscillation to the geared drive motor. The amplitude of the damping signal decays synchronously with the oscillation amplitude, which helps to suppress the oscillation amplitude when limit loop oscillation occurs in the differential speed compensation stage and gradually restores the gain coefficient after the oscillation is eliminated. The first proportion is greater than the second proportion, so that the overshoot acceleration phase, which is the precursor to oscillation, has a relatively stronger gain reduction force.

[0025] The arc extinguishing and re-ignition state discrimination module is implemented using a state machine approach. When the welding power supply output voltage rises from the arc voltage range to the open-circuit voltage and the duration exceeds the first threshold, the arc is determined to be extinguished. The starting circuit is immediately disconnected and a lockout timer is started. During the lockout period, the starting circuit is forcibly kept disconnected. If the voltage drops back to the arc voltage range during the lockout period, the time interval between the drop and the extinguishing time is calculated. If it is shorter than the second threshold, it is determined to be a re-ignition after a momentary arc extinguishing and the lockout is maintained. If it is longer than or equal to the second threshold, it is determined to be a re-ignition of the arc and the lockout is released. The delayed conduction logic is then re-executed according to the second preset duration. Both the first and second thresholds are based on the output ripple period as the reference unit, and the second threshold is greater than the first threshold. This helps to lock the starting circuit in a timely manner when the arc is extinguished, reducing the possibility of the traveling wheel continuing to run empty in the absence of an arc. At the same time, it establishes a time interval-based distinction between momentary arc extinguishing and re-ignition and operator-initiated arc ignition.

[0026] The feedback deviation judgment submodule monitors the deviation between the actual wire feeding speed feedback value and the target command value of the external wire feeder in real time. When the absolute value of the deviation exceeds the preset deviation threshold and the duration exceeds the preset time window, it determines that the linkage has failed and forcibly switches to open-loop holding mode. This decouples the wire feeding speed from the real-time speed signal of the geared drive motor and allows the wire to be fed continuously at a safe feeding speed. This helps reduce the risk of the weld amount continuously deviating from the expected value or the wire burning back when the actual wire feeding speed deviates from the target value due to the wire feeder stalling, slippage, or mechanical jamming. Simultaneously with switching to open-loop holding mode, the median value of the wire feeding speed within a time period three times the duration of the reverse speed adjustment command is read back from the historical wire feeding speed record at the moment the reverse speed adjustment command is triggered, and used as a replacement command output. This ensures that the wire feeding speed operates stably at the historical typical value during the open-loop holding period. Once the deviation falls back to within the threshold and stabilizes for more than the preset time window, the linkage modulation is automatically restored. This helps maintain the continuity of the wire feeding process when the wire feeder experiences temporary abnormalities and automatically returns to normal operation mode after the abnormality is resolved.

[0027] The high-frequency time base signal source within the control circuit provides a unified time reference for multiple tasks, including load determination, wire feeding linkage, slip determination, and start-up control. Each task occupies time slot resources in a time-division multiplexing manner according to priority. Load determination occupies the first time slot, and its determination result provides input conditions for subsequent tasks. The status register latches the output state of each determination at the beginning of each sampling period and synchronizes the latched value to all determination logic, ensuring that each determination is calculated based on the same set of state data within the same sampling period. When instructions output by two determinations within the same sampling period act on the same execution unit, the control circuit executes the higher-priority instruction in priority order and caches the lower-priority instruction for execution in the next sampling period. This approach helps reduce the risk of causal relationship errors caused by data asynchrony between determination logics and also helps reduce timing conflicts arising from multiple tasks competing for control resources.

[0028] The repeated trigger suppression module continuously monitors whether the same traveling wheel repeatedly experiences a continuous decrease in load and triggers a reverse speed adjustment command within three consecutive unit travel segments. Simultaneously, it checks the time it takes for the output half-shaft speed of the traveling wheel to recover to a stable value after each reverse speed adjustment command. If the recovery time is greater than a preset time threshold each time, it indicates that the traveling wheel requires a long time to re-establish a stable ground load after each detachment, and there is a persistent support abnormality on the workpiece surface. When both conditions are met, it is determined that there is a continuous indentation or obstacle on the workpiece surface, and its size exceeds the traveling wheel's obstacle-crossing capability. At this time, the triggering of subsequent reverse speed adjustment commands is terminated, and the output of the reduction drive motor is switched to slow mode, with the slow speed reduced to 30% of the normal welding speed. The speed difference between the two output half-shafts of the micro planetary differential is forcibly locked to zero, and an indicator light emits an alarm signal. These measures help reduce the amplitude and frequency of repeated system adjustments under persistent abnormal conditions where the traveling wheel repeatedly detaches and cannot establish a stable ground, reducing the additional wear on the actuators that may be caused by frequent speed adjustments. Simultaneously, slowing and locking the differential reduce the possibility of the traveling wheel slipping laterally at the edge of an obstacle. After the operator switches the mode selection switch to the stop position and then back to the travel position, the module automatically resets and resumes normal function, providing the operator with a clear intervention and reset path.

[0029] 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

[0030] Figure 1 This is a three-dimensional structural diagram of the handheld self-propelled welding torch with anti-tipping function of the present invention.

[0031] Figure 2 for Figure 1 A magnified schematic diagram of the structure at position A in the middle;

[0032] Figure 3 To compare the welding effect of the control group with that of the device in this embodiment;

[0033] Figure 4 This diagram illustrates the usage status of the device of the present invention.

[0034] The components are as follows: 1-Welding torch body; 2-Reduction drive motor; 3-Wire feeding nozzle; 4-Transmission coupling; 5-Universal joint; 501-Driving sleeve of universal joint; 502-Driven sleeve of universal joint; 6-Miniature planetary differential; 601-Power input shaft of miniature planetary differential; 602-Output half-shaft of miniature planetary differential; 7-Rigid support bracket; 8-Walking wheel; 9-Gas protection nozzle; 10-Speed ​​control knob; 11-Mode selection toggle switch; 12-Cold wire feeding tube. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, so that those skilled in the art can implement it based on the description. It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials described are commercially available unless otherwise specified.

[0036] like Figures 1-2As shown, this embodiment provides a handheld self-propelled welding torch with anti-tipping function for cold wire assisted gas shielded welding operations. The operator holds the welding torch body 1 and pushes it along the weld seam. The reduction drive motor 2 drives the traveling wheels 8 to roll, making the welding torch move along the welding direction. The welding torch body 1 is generally pistol-shaped, and the operator holds the middle of the torch body to perform welding operations. A gas shielding nozzle 9 is provided at the front end of the welding torch body 1. The gas shielding nozzle 9 is a copper conical tube, and its axis extends horizontally along the welding travel direction, spraying shielding gas into the welding area. A mounting groove is opened at the bottom of the welding torch body 1. The mounting groove is a rectangular groove with the opening facing downwards, and the bottom of the groove is located inside the torch body. The reduction drive motor 2 is fixed in the mounting groove. It is a brushed reduction drive motor with a reduction ratio of 20:1. Its output shaft is arranged horizontally and parallel to the length direction of the welding torch body 1. The output end of the geared drive motor 2 is connected to the driving sleeve 501 of the universal joint 5 via the transmission coupling 4. The driven sleeve 502 of the universal joint 5 is connected to the power input shaft 601 of the miniature planetary differential 6. A wheel 8 is connected to each of the two output half-shafts 602 of the miniature planetary differential 6. The included angle between the axes of the two sleeves of the universal joint 5 is 20 degrees, with the bending direction facing the side where the gas protection nozzle 9 is located. This ensures that the miniature planetary differential 6 and the two wheels 8 located at the end of the driven sleeve 502 are arranged facing the gas protection nozzle 9, with the two wheels 8 positioned diagonally below the gas protection nozzle 9. The rigid support bracket 7 is a one-piece bent steel plate with multiple mounting holes, which are bolted to the base of the geared drive motor 2, the bearing seats of the two sleeves of the universal joint 5, and the housing of the miniature planetary differential 6. The rigid support bracket 7 locks the angle between the driving sleeve 501 and the driven sleeve 502, ensuring that the universal joint 5 does not change its bending angle due to the reaction torque during torque transmission. Simultaneously, it restricts the rotation of the miniature planetary differential 6 around the power input shaft 601, preventing the traveling wheels 8 from overturning around the power input shaft 601 due to the reaction torque during rolling. The projection of the gas protection nozzle 9 onto the horizontal plane is located between the two traveling wheels 8. The projection distance between the axis of the gas protection nozzle 9 and the center line of the common axle of the two traveling wheels 8 in the welding travel direction is no greater than the radius of the traveling wheels 8. In this embodiment, the diameter of the traveling wheels 8 is 25 mm, the projection distance is 10 mm, and the axis of the gas protection nozzle 9 essentially falls on the vertical plane of the line connecting the grounding points of the two traveling wheels 8.

[0037] The welding torch body 1 also houses a control circuit, which is electrically connected to the geared drive motor 2 via wires and includes a speed detection terminal. The speeds of the two output half-shafts 602 are detected by an incremental photoelectric encoder mounted on the housing of the miniature planetary differential 6. The encoder has 1024 lines, and after being quadrupled in frequency, it outputs 4096 pulses per revolution. The pulse signals are shaped and then sent to the speed detection terminal of the control circuit. The control circuit is based on a microcontroller with a main frequency of 72 MHz and uses a periodic speed measurement method: measuring the time interval Tp between two adjacent encoder pulses, with the speed value n = 60 ÷ (P × Tp), where P is the number of encoder pulses per revolution, taken as 4096, Tp is in seconds, and n is in revolutions per minute. The control circuit performs the main discrimination task with a sampling period of 5 milliseconds. Within each sampling period, it reads the latest rotational speed values ​​of the two output half-shafts 602 and calculates the change in rotational speed of each output half-shaft 602 in the current sampling period relative to the previous sampling period, Δn = n(k) - n(k-1), where n(k) is the rotational speed value read in the current sampling period, and n(k-1) is the rotational speed value in the previous sampling period. Based on the walking conditions of this embodiment, at a normal walking speed of 250 mm / min and a walking wheel diameter of 25 mm, the rotational speed of the output half-shaft 602 is 3.2 rpm, the encoder pulse time interval Tp is 4.6 milliseconds, and the rotational speed value is updated every 4.6 milliseconds, matching the 5 millisecond sampling period. When the rotational speed of any output half-shaft 602 increases continuously for three consecutive sampling cycles, and the absolute value of the increment Δn in each of these three sampling cycles increases sequentially, the control circuit determines that the load on the traveling wheel 8 corresponding to that output half-shaft 602 is continuously decreasing, and records the orientation of the traveling wheel 8, which is determined by whether the output half-shaft 602 is located to the left or right of the welding torch's travel direction. The physical basis for this determination is: when the traveling wheel 8 is normally grounded, it bears the frictional load of the workpiece surface, and its rotational speed is relatively stable; when the traveling wheel 8 enters the unsupported travel segment and gradually detaches from the workpiece surface, the frictional load gradually decreases, and the rotational speed of the output half-shaft 602 increases due to the decrease in load. As the degree of detachment intensifies, the acceleration of the speed increase also increases, which is manifested as the absolute value of the increment Δn increasing sequentially. Within one sampling cycle after the determination, the control circuit outputs a reverse speed adjustment command to the reduction drive motor 2. In this embodiment, the reverse speed regulation command uses a triangular wave speed increment curve: the command period Tc is 150 milliseconds. In the first half of 75 milliseconds, the speed increment rises linearly from zero to Δnmax, and in the second half of 75 milliseconds, it falls linearly back to zero from Δnmax. Δnmax is taken as 40% of the current speed of the output half-shaft 602 at the time of command output. The speed of the reduction drive motor 2 therefore increases first and then decreases. This speed change is transmitted to the power input shaft 601 of the miniature planetary differential 6 through the transmission coupling 4 and the universal joint 5, and then distributed by the miniature planetary differential 6 to the two output half-shafts 602.The miniature planetary differential 6 allows the two output half-shafts 602 to rotate at different speeds. The other traveling wheel 8, still in the grounded state, experiences accelerated and then decelerated rotation, while the traveling wheel 8, whose load has been reduced, does not have a decisive impact on the welding torch posture. The instantaneous acceleration of the grounded traveling wheel 8 generates an additional downward driving force on the workpiece surface. This force forms a torque opposite to the pitch direction relative to the center of mass of the welding torch body 1. At the critical moment of support loss, it presses down on the front end of the welding torch body 1, i.e., the end where the gas protection nozzle 9 is located, suppressing the front pitch caused by the traveling wheel 8 detaching. Calculated with a traveling wheel 8 diameter of 25 mm and a normal traveling speed of 250 mm / min, the time it takes for the traveling wheel 8 to rotate one revolution is 18.8 seconds. The instruction cycle of the reverse speed adjustment command, 150 milliseconds, does not exceed the time it takes for a single traveling wheel 8 to rotate one revolution. The program logic in the control circuit uses an interrupt response method to process the encoder pulse signal. After each sampling cycle, the main loop uniformly executes the load state judgment and reverse speed adjustment command output, ensuring the timing consistency of each judgment.

[0038] The control circuit also includes a differential speed determination module. This module acquires the speed difference signal ΔN = nL - nR between the two output half-shafts 602, where nL and nR are the instantaneous speeds of the left and right output half-shafts 602, respectively. It then compares this speed difference signal with a preset normal differential speed reference range. The normal differential speed reference range is automatically acquired during the calibration phase before each welding operation: during calibration, the operator pushes the welding torch in a straight line with both traveling wheels 8 stably grounded. The control circuit records the maximum and minimum values ​​of the speed difference signal within 3 seconds, using this range as the normal differential speed reference range for this welding operation, and stores it in the control circuit's memory. When the speed difference signal exceeds the normal differential speed reference range, the differential speed determination module determines the direction of the speed difference signal, i.e., whether the traveling wheel 8 with the higher speed is located on the left or right side, and compares this direction with the orientation of the traveling wheel 8 whose load is continuously decreasing. If the direction of the speed difference signal and the orientation of the traveling wheel 8 whose load is continuously decreasing are on the same side, the speed difference signal is determined to be an abnormal increase in speed caused by a change in unsupported state, and no compensation action is triggered. If the direction of the speed difference signal is on a different side from the orientation of the continuously decreasing load on the traveling wheel 8, the speed difference signal is determined to be caused by lateral slippage of the traveling wheel 8. In the next sampling cycle, the differential speed determination module superimposes a difference compensation signal based on the base speed command, causing the target speed of the output half-shaft 602 on the lower speed side to gradually increase at a preset gradual rate, while the target speed of the output half-shaft 602 on the higher speed side gradually decreases at the same gradual rate, until the speed difference signal falls back to the normal differential speed reference range. The operator sets the traveling speed using the speed adjustment knob 10 on the welding torch body 1. The control circuit converts this traveling speed into a base speed command. In this embodiment, the normal traveling speed is 250 mm / min, corresponding to a base speed of 3.2 rpm for the output half-shaft 602. The gradual rate is set to 5% of the current speed difference value adjusted each sampling cycle to prevent excessively fast compensation speeds from causing new oscillations. The determination of continuous load reduction and the determination of lateral slip are executed sequentially within the same sampling period. The determination of continuous load reduction is executed first, followed by the determination of lateral slip. This allows the determination of lateral slip to directly use the result of the determination of continuous load reduction as an input condition, thus maintaining the causal relationship between the two.

[0039] The control circuit also includes a start-up control terminal, which is connected to the output voltage detection circuit of the welding power supply via a signal line. The output voltage detection circuit uses a resistor divider network in conjunction with an analog-to-digital converter to monitor the output voltage value of the main circuit of the welding power supply in real time and generate a voltage detection signal. In this embodiment, the no-load voltage of the welding power supply is 60V to 80V, the preset threshold is 30V, and the arc voltage range is 18V to 45V. Before the start-up circuit of the geared drive motor 2 is turned on, when the output voltage of the welding power supply is lower than the preset threshold, the control circuit keeps the start-up circuit disconnected. When the output voltage reaches the preset threshold and remains stable for more than a first preset duration, the control circuit determines that the welding circuit has established a no-load voltage, but does not immediately turn on the start-up circuit; instead, it continues to monitor whether the output voltage drops from the no-load voltage range to the arc voltage range. The first preset duration is 100 milliseconds, used to filter out voltage oscillations at the moment of welding power supply startup. When it is detected that the output voltage has dropped from the no-load voltage range to the arc voltage range and remains stable for more than a second preset duration, the control circuit determines that the arc has been stably established and turns on the start-up circuit of the geared drive motor 2. The second preset duration is 100 milliseconds, used to confirm that the arc has been stably ignited rather than failing to ignite momentarily. The starting circuit and the speed controller of the geared drive motor 2 operate independently in parallel. The starting circuit is responsible for switching the power supply to the geared drive motor 2 on and off, and the speed controller is responsible for adjusting the speed of the geared drive motor 2 after the circuit is turned on. Once the starting circuit is turned on, its on / off state is controlled by the arc interruption and re-ignition state discrimination module, and is no longer directly controlled by the instantaneous value of the output voltage, so as to avoid the starting circuit being falsely disconnected when the arc voltage is lower than the preset threshold during normal welding. During the duration of the reverse speed adjustment command, the control circuit keeps the starting circuit on, ensuring that the execution of the reverse speed adjustment command is not interrupted by the on / off state of the starting circuit.

[0040] A cold wire feed tube 12 is fixed to the welding torch body 1. The cold wire feed tube 12 is fixed to the side wall of the welding torch body 1 by an aluminum alloy clamp. One end of the clamp is fixed to the welding torch body 1 with a screw, and the other end has a through hole for the cold wire feed tube 12 to pass through and is locked with a set screw. The cold wire feed tube 12 is a copper tube with an inner diameter of 1.2 mm. It extends along the length of the welding torch body 1, and its rear end is connected to the wire feeding hose fed by an external cold wire feeder. The front end of the wire feed tube extends to the vicinity of the gas protection nozzle 9. The inner surface of the wire feed tube 12 has an internal thread, and the outer surface of the wire feeding nozzle 3 has an external thread that matches it. The wire feeding nozzle 3 is threadedly connected to the wire feed tube 12. The wire feeding nozzle 3 is made of copper and has a wire outlet at the front end. The inner diameter of the wire outlet is slightly larger than the diameter of the cold wire. The wire feed nozzle 3 has its outlet facing the welding area below the gas shielded nozzle 9. The axis of the wire feed nozzle 3 intersects the axis of the gas shielded nozzle 9 in the welding area below the gas shielded nozzle 9, with an angle of 45 degrees between the two axes. The welding torch body 1 is also equipped with a wire feed speed linkage modulation module, which is located on the same circuit board as the control circuit. The wire feed speed linkage modulation module uses the real-time rotational speed signal of the reduction drive motor 2 as its input variable, which is taken from the motor drive feedback terminal of the control circuit. The target wire feed speed command value Vwire feed is calculated using the following formula: Vwire feed = π × D × n × K, where D is the diameter of the traveling wheel 8 (mm), n is the real-time rotational speed of the output half-shaft 602 (rpm), K is the dimensionless wire feed speed matching coefficient, and π × D × n converts the rotational speed of the output half-shaft 602 into the welding torch's travel speed (mm / min). The target wire feeding speed command value is output to the speed control terminal of the external cold wire feeder via digital-to-analog conversion or PWM signal, ensuring a constant ratio between the cold wire feeding speed and the welding torch travel speed. The matching coefficient K is calibrated based on the cold wire diameter through welding process tests: K = 1.0 for a 1.2 mm diameter cold wire and K = 1.1 for a 1.6 mm diameter cold wire. Based on a 25 mm diameter traveling wheel 8 and a normal traveling speed of 250 mm / min, with an output half-shaft 602 rotation speed of 3.2 rpm, the target wire feeding speed for a 1.2 mm diameter cold wire is 251 mm / min, essentially consistent with the welding torch travel speed. The wire feeding speed linkage modulation module is also connected to the control circuit, receiving a load reduction judgment signal output by the control circuit. When the control circuit determines that the load continues to decrease and outputs a reverse speed regulation command, the wire feeding speed linkage modulation module superimposes a transient wire feeding speed compensation amount ΔV(t)=-Kh×Δn(t) on the basic linkage value, where Δn(t) is the speed increment of the output half-shaft 602 caused by the reverse speed regulation command (rpm), and Kh is the wire feeding compensation coefficient, which is taken as 0.5 (mm / min) / (rpm).The reverse speed control command causes the speed of the geared drive motor 2 to first increase and then decrease, resulting in accelerated and then decelerated rotation of the grounded traveling wheel 8. The front end of the welding torch body 1 is pressed down, and the distance between the gas protective nozzle 9 and the workpiece surface decreases in a short time. ΔV(t) becomes negative, meaning the wire feeding speed decreases from the basic linkage value. This, combined with the reduction in the height of the gas protective nozzle 9, maintains the relative distance between the cold wire outlet and the workpiece surface. After compensation, the wire feeding speed returns to the basic linkage value. This compensation amount and the reverse speed control command are triggered simultaneously by the same timer channel, have the same duration, and end simultaneously. The timer channel outputs two synchronous signals: one is sent to the speed controller of the geared drive motor 2 to execute the reverse speed control command, and the other is sent to the speed control terminal of the external cold wire feeder to execute wire feeding speed compensation.

[0041] The control circuit also includes a three-stage filtering module for the rotational speed signal. This module divides the time domain into three consecutive time periods: a front-end stabilization window, a middle-end discrimination window, and a back-end confirmation window. In this embodiment, the front-end stabilization window is 10 milliseconds, the middle-end discrimination window is 25 milliseconds, and the back-end confirmation window is 10 milliseconds, for a total processing time of 45 milliseconds, which is less than one-quarter of the 18.8-second rotational cycle of the traveling wheel 8. Within the front-end stabilization window, the control circuit collects rotational speed data from the two output half-shafts 602 at a frequency of 1 kHz, collecting a total of 10 sampling points. The fundamental rotational speed value n0 = (1 ÷ N) × Σn(i) and the background noise amplitude σ = √[(1 ÷ N) × Σ(n(i) - n0)] are calculated. 2In the formula, N is the number of sampling points, taken as 10, and n(i) is the rotational speed value of the i-th sampling point within the window. After calculating the fundamental rotational speed value and the background noise amplitude, the control circuit compares the instantaneous rotational speed of each sampling point with the fundamental rotational speed value. Only when the instantaneous rotational speed deviates from the fundamental rotational speed value by more than three times the background noise amplitude and the duration is longer than one sampling period, the rotational speed signal is allowed to enter the intermediate discrimination window. If no signal meeting the condition is detected in the front-end stable window, the three-stage screening process terminates after the window ends and does not enter the subsequent window. In the intermediate discrimination window, the control circuit calculates the rotational speed change of the rotational speed signal relative to the previous sampling period and its increasing trend. Only when the rotational speed increases continuously for three consecutive sampling periods and the absolute value of the increment increases period by period, the signal is judged as a sign of reduced effective load and output to the back-end confirmation window. If the rotational speed change does not meet the requirement of increasing continuously for three consecutive sampling periods or the absolute value of the increment does not increase period by period, the signal is judged as an invalid fluctuation and is not transmitted to the back-end confirmation window. The three-stage screening process terminates after the intermediate discrimination window is completed. Within the backend confirmation window, the control circuit cross-validates the signal with the load state of the same output half-shaft 602 in the previous sampling period. The load state of the previous sampling period is stored in the random access memory of the control circuit. If the rotational speed of the corresponding traveling wheel 8 was already increasing in the previous period, it indicates that the load reduction trend of the traveling wheel 8 had already started in the previous period. If it is triggered again, it will cause repeated actions, and the current judgment will be cancelled. If the rotational speed of the corresponding traveling wheel 8 was stable in the previous period, it indicates that this is the first time that the traveling wheel 8 has shown a load reduction trend, and the reverse speed adjustment command is confirmed to be triggered.

[0042] The differential speed determination module also includes a gain adjustment submodule. This submodule calculates the first derivative of the speed difference between the two output half-shafts 602 in real time: g(k) = [ΔN(k) - ΔN(k-1)] ÷ Ts, where ΔN(k) is the speed difference signal (rpm) in the current sampling period, ΔN(k-1) is the speed difference signal in the previous sampling period, Ts is the sampling period (5 milliseconds), and g(k) is in rpm. When the first derivative of the speed difference exceeds a preset acceleration threshold and continues to increase, the gain adjustment submodule determines that the current difference compensation is in the acceleration phase and automatically reduces the gain coefficient of the difference compensation signal by a first proportion. The preset acceleration threshold can be between 500 rpm and 1500 rpm; in this embodiment, it is 1000 rpm. The first proportion is 30%. In the acceleration phase, if the difference compensation signal continues to be output with the original gain coefficient, the rate of increase in the compensation amount will exceed the actual requirement, resulting in overshoot. When the first derivative of the speed difference falls below a preset acceleration threshold or begins to decrease, the gain adjustment submodule determines that the current difference compensation is in a deceleration callback phase and gradually restores the gain coefficient to the base value. The restoration rate is 10% of the difference between the base value and the current value per sampling cycle. The gain adjustment submodule is also equipped with an oscillation counter to monitor the number of positive and negative alternations of the speed difference signal within a preset time window. The preset time window is 200 milliseconds, and the preset frequency is 10 times per second. When the speed difference signal alternates between positive and negative at a frequency not lower than a preset frequency within a preset time window, the system is determined to be in an oscillation state. The gain coefficient of the difference compensation signal is reduced by a second proportion, which is 15%. Simultaneously, a vibration damping signal ud(t) = -kd × A(t) × sin(2π × fo × t) is superimposed on the output command of the reduction drive motor 2, where fo is the currently detected oscillation frequency, A(t) is the current oscillation amplitude, and kd is the vibration damping gain coefficient, initially set to 0.5. The phase of the vibration damping signal is locked 180 degrees out of phase with the oscillation signal via a phase-locked loop, and the amplitude of the vibration damping signal decays synchronously with the decay of the oscillation amplitude. When the oscillation counter records that the alternating frequency of positive and negative changes has dropped below the preset frequency for three consecutive oscillation cycles, the limit loop oscillation is determined to be eliminated, and the gain coefficient is gradually restored to the base value. The first proportion is greater than the second proportion: the overshoot acceleration stage is the precursor stage of oscillation, which needs to be suppressed in advance with a larger gain reduction; after the oscillation occurs, it is necessary to retain a certain driving capability while suppressing the oscillation to avoid the welding torch losing directional control.

[0043] The control circuit also includes an arc extinguishing and re-ignition state discrimination module, implemented as a state machine, comprising standby state, ignition waiting state, walking conduction state, arc extinguishing lockout state, and re-ignition discrimination state. When the output voltage of the welding power supply rises from the arc voltage range to the open-circuit voltage and the duration exceeds the first threshold, the control circuit determines that the arc has been extinguished, immediately disconnects the starting circuit of the reduction drive motor 2, and simultaneously starts a lockout timer and locks the conduction function of the starting circuit until the lockout timer returns to zero. The preset duration of the lockout timer is 1000 milliseconds. During the lockout timer's countdown, the starting circuit is forcibly kept disconnected and is not directly controlled by the welding power supply output voltage state or the operator's walking commands. If the output voltage of the welding power supply drops back to the arc voltage range during the lockout period, the control circuit does not immediately reconnect the starting circuit, but instead initiates the re-ignition discrimination logic: calculating the time interval between the moment the drop occurs and the moment the arc is extinguished, which is obtained by reading the current count value of the lockout timer. If the time interval is less than the second threshold, it is determined to be a re-ignition after a momentary arc interruption. The starting circuit remains locked, and the lock timer continues to count down until it reaches zero. If the time interval is greater than or equal to the second threshold, it is determined to be a re-arcing of the arc. The lock state is released, the lock timer is stopped, and the delayed conduction logic of the starting circuit is re-executed according to the second preset duration, i.e., the timing is restarted. The starting circuit is activated after the second preset duration is reached. Both the first and second thresholds are set based on the period of the welding power supply output ripple: in this embodiment, the period of the welding power supply output ripple is 20 milliseconds, the first threshold is 100 milliseconds (5 times the ripple period), and the second threshold is 300 milliseconds (15 times the ripple period). The second threshold is greater than the first threshold. The reason for this is that arc interruption determination only requires confirmation that the voltage has indeed risen back to the no-load and remained stable for several ripple periods, which requires a short confirmation time. However, distinguishing between re-ignition after a momentary arc interruption and operator-initiated arc requires a sufficiently long time interval to eliminate momentary disturbances. Therefore, the second threshold is greater than the first threshold. The first threshold is greater than the single ripple period to ensure that normal voltage ripple fluctuations are not misjudged as arc breaks.

[0044] The wire feeding speed linkage modulation module also includes a feedback deviation discrimination submodule, which monitors in real time the deviation between the actual wire feeding speed feedback value of the external cold wire feeder and the target wire feeding speed command value output by the wire feeding speed linkage modulation module. The external cold wire feeder is equipped with a built-in encoder, whose output actual speed pulse signal is fed back to the input of the control circuit via a signal line. The control circuit obtains the actual wire feeding speed value through frequency measurement. The deviation is the absolute value of the actual wire feeding speed feedback value minus the target wire feeding speed command value. When the absolute value of the deviation exceeds a preset deviation threshold and the duration exceeds a preset time window, the current wire feeding speed linkage is determined to be faulty, and the wire feeding speed control mode is forcibly switched from linkage modulation mode to open-loop holding mode. The preset deviation threshold is 15% of the target wire feeding speed command value, and the preset time window is 300 milliseconds. In open-loop holding mode, the wire feeding speed is decoupled from the real-time speed signal of the geared drive motor 2, and the wire is continuously fed at a preset safe wire feeding speed. The safe wire feeding speed is 60% of the basic wire feeding speed under normal welding conditions to avoid wire feeding interruption causing cold wire to burn back to the wire feeding guide nozzle 3, and also to avoid the cold wire being pushed out of the molten pool due to excessive wire feeding. Simultaneously with entering open-loop holding mode, the feedback deviation judgment submodule starts a backtracking timer, backtracking the wire feeding speed history record at the moment the reverse speed adjustment command is triggered, and retrieving the median value of the wire feeding speed within a time period three times the duration of the reverse speed adjustment command: the reverse speed adjustment command duration is 150 milliseconds, and the backtracking time period is 450 milliseconds before the trigger. The historical wire feeding speed record is stored in the control circuit's circular buffer. The buffer records the current wire feeding speed command value and the actual feedback value every sampling cycle, with a buffer depth of 500 milliseconds, sufficient to cover the 450 milliseconds backtracking requirement. The median value is taken as the median of all recorded values ​​within the specified time period, sorted by size. This median value is used as the replacement wire feeding speed command and output to the external cold wire feeder to stabilize the wire feeding speed at historical typical values. The deviation is then continuously monitored. When the absolute value of the deviation falls below the preset deviation threshold and remains stable for an extended period beyond the preset time window, it is determined that the external wire feeder has regained normal tracking capability. The open-loop hold mode is then exited, and the normal operation of the wire feeding speed linkage modulation module is restored. If the deviation continues to exceed the threshold in open-loop hold mode, it indicates a persistent fault in the wire feeding system. The open-loop hold mode is maintained until operator intervention.

[0045] The control circuit includes a high-frequency time base signal source, generated by frequency multiplication of a crystal oscillator on the control circuit board via a phase-locked loop. In this embodiment, the rated maximum speed of the geared drive motor 2 is 3000 rpm, with a reduction ratio of 20:1. The maximum speed of the output half-shaft 602 is 150 rpm (2.5 rpm), and the encoder outputs 4096 pulses per revolution. The pulse frequency corresponding to the maximum speed of the output half-shaft 602 is 10240 Hz. The frequency of the high-frequency time base signal source is 20480 Hz, which is an integer multiple of twice the pulse frequency corresponding to the maximum speed, and not less than 1000 Hz. The high-frequency time base signal source is shared by the determination of continuous load reduction, the linkage modulation of wire feeding speed, the determination of lateral slippage, and the conduction control of the starting circuit. Time slot resources are occupied in a time-division multiplexing manner according to priority. The basic cycle of time-division multiplexing is one complete cycle of the high-frequency time base signal, i.e., 0.0488 milliseconds. Each cycle is divided into four time slots in chronological order: the first time slot is occupied by the determination of continuous load reduction, the second time slot is occupied by the linkage modulation of wire feeding speed, the third time slot is occupied by the determination of lateral slip, and the fourth time slot is occupied by the conduction control of the starting circuit. The determination of continuous load reduction is arranged at the beginning of each high-frequency cycle, and its result is the trigger basis for whether the lateral slip determination and the linkage modulation of wire feeding speed respond. When the instructions output by two determinations in the same sampling cycle act on the same execution unit, the control circuit executes the high-priority instruction in priority order and buffers the low-priority instruction for execution in the next sampling cycle: when the determination of continuous load reduction outputs a reverse speed adjustment instruction requiring the deceleration drive motor 2 to adjust its speed transiently, and the determination of lateral slip outputs a difference compensation signal also requiring the deceleration drive motor 2 to adjust its speed, the two act on the same drive instruction, which constitutes a conflict. The control circuit executes the higher-priority reverse speed adjustment instruction, and the difference compensation signal is stored in the instruction buffer area and executed in priority order in the next sampling cycle. Each decision is also equipped with a status register. Each decision logic corresponds to a status register. The status register latches the output state of each decision at the end of the previous sampling period at the beginning of each sampling period. The latching operation is triggered by the rising edge of the high-frequency time base signal. After the latching is completed, the latched value is synchronized to all decisions through the data bus, so that each decision is calculated based on the same set of status data in the same sampling period, avoiding one decision using the old status data of the previous sampling period while another decision uses the new status data of the current sampling period.

[0046] The control circuit also includes a repetitive trigger suppression module, which continuously monitors whether the same traveling wheel 8 repeatedly experiences a continuous decrease in load and triggers a reverse speed adjustment command within multiple consecutive unit travel segments. The length of a unit travel segment is equal to the circumference of one revolution of the traveling wheel 8 after contact with the ground. Assuming a diameter of 25 mm for the traveling wheel 8, the length of a unit travel segment is 78.5 mm. The control circuit calculates the travel distance of the welding torch by accumulating the number of rotations of the traveling wheel 8 and its diameter. A counter increments by one every time the accumulated travel distance reaches the length of a unit travel segment. When the control circuit continuously detects that the same traveling wheel 8 experiences a continuous decrease in load and triggers a reverse speed adjustment command within three consecutive unit travel segments, the repetitive trigger suppression module further checks the time it takes for the output half-shaft 602 corresponding to the traveling wheel 8 to recover to a stable value after each reverse speed adjustment command. The criterion for determining whether the speed has recovered to a stable value is: the change in the speed of the output half-shaft 602 within five consecutive sampling periods is less than a stability threshold, which is 1% of the current speed of the output half-shaft 602. The recovery time is calculated from the end of the reverse speed adjustment command until the time when the judgment criterion is met. Under normal operating conditions, the recovery time is completed within several sampling cycles. The preset time threshold is 8 seconds, which is less than the time interval between two consecutive load reduction events, so that the recovery time check can be completed before the next segment event occurs. If the time to recover to a stable value is greater than the preset time threshold each time, it indicates that the traveling wheel 8 needs a long time to re-establish a stable ground load after each disengagement, and there is a continuous support abnormality on the workpiece surface. When the above two conditions are met at the same time, the repeated trigger suppression module determines that there is a continuous dent or obstacle on the current workpiece surface, and the size of the dent or obstacle exceeds the obstacle crossing ability of the traveling wheel 8. Continuing to execute the reverse speed adjustment command is meaningless and may cause the control system to be in a state of repeated adjustment for a long time. Then, the triggering of subsequent reverse speed adjustment commands is terminated. No matter how the speed signal changes, the system no longer outputs any reverse speed adjustment command to the reduction drive motor 2, and switches the output command of the reduction drive motor 2 to the slow mode. In slow mode, the walking speed is reduced to 30% of the normal welding speed. Based on a normal walking speed of 250 mm / min, the slow speed is 75 mm / min. The speed difference between the two output half-shafts 602 of the micro planetary differential 6 is forcibly locked to zero, and the two walking wheels 8 rotate at the same speed, without differential action, thus preventing lateral slippage at the edge of obstacles. Simultaneously, the indicator light on the welding torch body 1 flashes rapidly 5 times per second to issue an alarm signal, distinguishing it from the normal state and other alarm states. When the operator moves the mode selection switch 11 on the welding torch body 1 to the stop position and then back to the walking position, the repeated trigger suppression module automatically resets, clears the global shielding flag, restores the normal triggering function of the reverse speed adjustment command, exits slow mode, and resumes normal walking speed.

[0047] Effect comparison experiment

[0048] To verify the technical effectiveness of the device in this embodiment, the following conditions were uniformly used in all comparative experiments: Gas metal arc welding power supply, open-circuit voltage 60V to 80V, arc voltage range 18V to 45V; base material was Q235 low-carbon steel plate, 10mm thick, with a 60-degree V-groove; cold wire was ER50-6 welding wire with a diameter of 1.2mm; shielding gas was a mixture of 80%Ar + 20%CO2, with a flow rate of 15 liters / minute; normal travel speed was 250 mm / minute, and the travel wheels 8 had a diameter of 25mm. The control group consisted of a handheld self-propelled welding torch without reverse speed control, differential compensation, and wire feed speed linkage. Weld reinforcement height and weld width were obtained through metallographic measurement of the weld cross-section. The height change of the gas shielding nozzle 9 was recorded using a laser displacement sensor at 1 kHz, and the trajectory deviation was characterized by the lateral offset of the weld centerline relative to the groove centerline.

[0049] Experiment 1: Comparative Experiment on Anti-Pitching at the Workpiece End. Both the control group and the device in this embodiment traveled along the butt weld of a flat plate at a speed of 250 mm / min. After reaching the workpiece end, they continued traveling until the traveling wheels completely detached from the workpiece surface. The maximum change in the height of the gas protective nozzle 9 relative to the steady-state value, the fluctuation of weld height and weld width within 100 mm of the workpiece end were recorded during this process. Each was repeated 10 times, and the average value was taken. The results are shown in Table 1. At the critical moment of support loss, the device in this embodiment was driven by a reverse speed control command to instantaneously accelerate the grounded traveling wheels 8, generating an additional downward driving force on the workpiece surface and forming a torque opposite to the pitching direction. The height change of the gas protective nozzle 9 was controlled within 0.4 mm, and the fluctuation of weld height and weld width at the end was significantly smaller than that of the control devices. The welding effects of the control group and the device in this embodiment are as follows: Figure 3 As shown, where Figure 3 a represents the welding effect of the control group. Figure 3 b represents the effect of this implementation device.

[0050] Table 1 Comparative Experiment Results of Anti-Pitching at the Workpiece End

[0051] Experiment 2: Comparative Experiment of Differential Speed ​​Following for Curved Welds. Welding was performed at 250 mm / min on a curved weld with a radius of curvature of 300 mm and a central angle of 90 degrees. Lateral slippage was determined by the speed difference signal exceeding the normal differential speed reference range and its direction being different from the direction of the traveling wheel 8, whose load was continuously decreasing. The maximum lateral deviation of the weld trajectory and the number of lateral slippages of the traveling wheel 8 were recorded, each repeated 10 times and the average value taken. The results are shown in Table 2. In this embodiment, the differential compensation signal of the device synchronized the target speeds of the output half-shaft 602 on the lower and higher speed sides with the same gradual change rate, controlling the trajectory deviation within 1 mm, and no lateral slippage occurred throughout the entire process. In the control group, no differential speed compensation was set, and lateral slippage occurred frequently, with significant deviation of the weld trajectory.

[0052] Table 2. Results of the differential speed following experiment for curved welds

[0053] Experiment 3: Wire Feed Speed ​​Linkage Comparison Experiment. During welding, the travel speed was varied sinusoidally between 200 mm / min and 300 mm / min. The maximum following deviation of the wire feed speed relative to the target value and the fluctuation of the weld metal per unit length were recorded. During the triggering of the reverse speed adjustment command, the change in the wire extension relative to the steady-state value was recorded. Each experiment was repeated 10 times and the average value was taken. The results are shown in Table 3. The wire feed speed of the control group was fixed at the wire feed value corresponding to a travel speed of 250 mm / min and was not adjusted with the travel speed. In this embodiment, the wire feed speed linkage modulation module generates the target wire feed speed command value in real time according to V_wire feed = π × D × n × K. The maximum following deviation of the wire feed speed is 8 mm / min, and the fluctuation of the weld metal per unit length is ±2.5%. The transient compensation ΔV(t) = -Kh × Δn(t) superimposed during the reverse speed adjustment command reduces the change in wire extension to 1.2 mm.

[0054] Table 3. Results of the comparative experiment on wire feeding speed linkage

[0055] 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 handheld self-propelled welding torch with anti-tipping function, comprising a welding torch body (1), a gas protection nozzle (9) provided at the front end of the welding torch body (1), a reduction drive motor (2) and a miniature planetary differential (6) provided inside the welding torch body (1), the reduction drive motor (2) being connected to the power input shaft (601) of the miniature planetary differential (6), and a walking wheel (8) respectively connected to the two output half shafts (602) of the miniature planetary differential (6), the two walking wheels (8) being used to support the workpiece surface and drive the welding torch body (1) to move, characterized in that: The welding torch body (1) is also equipped with a control circuit, which is electrically connected to the geared drive motor (2). The control circuit is equipped with a speed detection terminal for detecting the speed of the two output half shafts (602). The control circuit is configured to read the speed values ​​of the two output half shafts (602) in each sampling period and calculate the speed change of each output half shaft (602) in the current sampling period relative to the previous sampling period. When the speed of any output half shaft (602) continues to increase for three consecutive sampling periods and the absolute value of the increment of each sampling period in the three sampling periods increases sequentially, the control circuit determines that the load of the walking wheel (8) corresponding to the output half shaft (602) is continuously decreasing and records the orientation of the walking wheel (8). In the sampling period after the determination, the control circuit outputs a reverse speed adjustment command to the geared drive motor (2) so that the speed of the geared drive motor (2) first increases and then decreases, thereby causing the other walking wheel (8) to obtain an acceleration and deceleration rotation. The duration of the reverse speed adjustment command does not exceed the time of one rotation of a single walking wheel (8).

2. The handheld self-propelled welding torch with anti-tipping function according to claim 1, characterized in that: The control circuit also includes a differential speed determination module. This module acquires the speed difference signal between the two output half-shafts (602) and compares it with a preset normal differential speed reference range. When the speed difference signal exceeds the normal differential speed reference range, the differential speed determination module determines the direction of the speed difference signal and compares it with the orientation of the continuously decreasing load wheel (8). If the direction of the speed difference signal is on the same side as the orientation of the continuously decreasing load wheel (8), then the speed difference signal is determined to be an abnormal increase in speed caused by a change in unsupported state, and no compensation action is triggered. If the direction of the speed difference signal is on the same side as the orientation of the continuously decreasing load wheel (8), then the differential speed difference signal is determined to be an abnormal increase in speed caused by a change in unsupported state, and no compensation action is triggered. If the positions of the wheels (8) are on different sides, the speed difference signal is determined to be caused by lateral slippage of the wheels (8). In the next sampling period, the differential speed determination module superimposes the difference compensation signal based on the basic speed command. The difference compensation signal causes the target speed of the output half shaft (602) on the side with lower speed to gradually increase at a preset gradual rate, while causing the target speed of the output half shaft (602) on the side with higher speed to gradually decrease at the same gradual rate, until the speed difference signal falls back to the normal differential speed reference range. The determination of continuous load reduction and the determination of lateral slippage are executed sequentially in the same sampling period. The determination of continuous load reduction is executed first, followed by the determination of lateral slippage.

3. The handheld self-propelled welding torch with anti-tipping function according to claim 2, characterized in that: The control circuit is also equipped with a start control terminal, which is connected to the output voltage detection circuit of the welding power supply. The output voltage detection circuit monitors the output voltage value of the main circuit of the welding power supply in real time and generates a corresponding voltage detection signal. The control circuit is configured to keep the start circuit disconnected before the start circuit of the geared drive motor (2) is turned on, when the output voltage of the welding power supply is lower than a preset threshold. When the output voltage of the welding power supply reaches the preset threshold and the stable time exceeds the first preset duration, the control circuit continues to monitor whether the output voltage of the welding power supply drops to the arc voltage range. When it is detected that the output voltage of the welding power supply drops from the no-load voltage range to the arc voltage range and the stable time exceeds the second preset duration, the control circuit turns on the start circuit of the geared drive motor (2). The start circuit and the speed regulator of the geared drive motor (2) operate independently in parallel, and the control circuit keeps the start circuit turned on during the reverse speed regulation command.

4. The handheld self-propelled welding torch with anti-tipping function according to claim 3, characterized in that: A cold wire feeding tube (12) is fixed on the welding torch body (1). The wire outlet end of the cold wire feeding tube (12) is connected to a wire feeding nozzle (3). A wire feeding speed linkage modulation module is also provided on the welding torch body (1). The wire feeding speed linkage modulation module takes the real-time speed signal of the reduction drive motor (2) as the input variable, multiplies the real-time speed signal by the preset wire feeding speed matching coefficient to generate the target wire feeding speed command value and outputs it to the speed control terminal of the external cold wire feeder, so that the feeding speed of the cold wire and the traveling speed of the welding torch are kept in a constant proportional relationship. The wire feeding speed linkage modulation module is also connected to the control circuit to receive control signals. The load output signal continuously decreases. When the control circuit determines that the load is continuously decreasing and outputs a reverse speed regulation command, the wire feeding speed linkage modulation module superimposes a transient wire feeding speed compensation amount on the basic linkage value. The direction of this compensation amount is opposite to the direction of the change in the height of the gas protection nozzle (9) caused by the reverse speed regulation command. That is, when the reverse speed regulation command reduces the distance between the gas protection nozzle (9) and the workpiece surface, the wire feeding speed decreases on the basis of the basic linkage value. After the compensation is completed, it returns to the basic linkage value. This compensation amount and the reverse speed regulation command are triggered simultaneously by the same timer channel, have the same duration, and end at the same time.

5. The handheld self-propelled welding torch with anti-tipping function according to claim 1, characterized in that: The control circuit also includes a three-stage filtering module for the speed signal. This module is divided into a front-end stabilization window, a middle-end discrimination window, and a back-end confirmation window in the time domain. Within the front-end stabilization window, the control circuit acquires the speed data of the two output half-shafts (602) and calculates the fundamental speed value and background noise amplitude. Only when the instantaneous speed deviates from the fundamental speed value by more than three times the background noise amplitude and the duration is greater than one sampling period is the speed signal allowed to enter the middle-end discrimination window. Within the middle-end discrimination window, the control circuit calculates the speed change of the speed signal relative to the previous sampling period and its increasing trend. Only when the instantaneous speed deviates from the fundamental speed value by more than three times the background noise amplitude and the duration is greater than one sampling period is the speed signal allowed to enter the middle-end discrimination window. When the rotational speed increases continuously for three consecutive sampling cycles and the absolute value of the increment increases cycle by cycle, the signal is determined as a sign of reduced effective load and output to the back-end confirmation window. In the back-end confirmation window, the control circuit cross-verifies the signal with the load status of the same output half shaft (602) in the previous sampling cycle. If the rotational speed of the corresponding walking wheel (8) in the previous cycle is already in an increasing state, the determination is cancelled. If the rotational speed of the corresponding walking wheel (8) in the previous cycle is in a stable state, the reverse speed regulation command is confirmed to be triggered. The total processing time of the three-stage screening module does not exceed one-quarter of the rotational cycle of a single walking wheel (8).

6. The handheld self-propelled welding torch with anti-tipping function according to claim 2, characterized in that: The differential speed determination module is also equipped with a gain adjustment submodule. The gain adjustment submodule calculates the first derivative of the speed difference between the two output half shafts (602) in real time. When the first derivative of the speed difference exceeds the preset acceleration threshold and continues to increase, it is determined that the current difference compensation is in the acceleration phase and the gain coefficient of the difference compensation signal is automatically reduced by the first proportion. When the first derivative of the speed difference is lower than the preset acceleration threshold or begins to decrease, the gain coefficient is gradually restored to the basic value. The gain adjustment submodule is also equipped with an oscillation counter. When the speed difference signal is detected to be alternating between positive and negative at a frequency not lower than the preset frequency within the preset time window, it is determined that the system has entered the oscillation state and the gain coefficient of the difference compensation signal is reduced by the second proportion. At the same time, a vibration damping signal with the same frequency and opposite phase as the oscillation is superimposed on the output command of the deceleration drive motor (2). The gain coefficient is gradually restored to the basic value after the oscillation counter records that the alternating frequency of positive and negative has dropped below the preset frequency in three consecutive oscillation cycles. The first proportion is greater than the second proportion, and the amplitude of the vibration damping signal is synchronously reduced with the decay of the oscillation amplitude.

7. The handheld self-propelled welding torch with anti-tipping function according to claim 3, characterized in that: The control circuit is also equipped with an arc extinguishing and re-ignition state discrimination module. When the output voltage of the welding power supply rises from the arc voltage range to the open voltage and the duration exceeds the first threshold, the control circuit determines that the arc has been extinguished and immediately disconnects the starting circuit of the deceleration drive motor (2). At the same time, it starts the locking timer and locks the conduction function of the starting circuit until the locking timer returns to zero. If the output voltage of the welding power supply drops back to the arc voltage range during the locking timer's timing, the control circuit calculates the time interval between the time of the drop and the time of arc extinguishing. If the time interval is less than the second threshold, it is determined to be re-ignition after instantaneous arc extinguishing and the locking state of the starting circuit is maintained. If the time interval is greater than or equal to the second threshold, it is determined to be re-ignition and the locking is released. The delayed conduction logic of the starting circuit is re-executed according to the second preset duration. The values ​​of the first threshold and the second threshold are based on the period of the welding power supply output ripple, and the second threshold is greater than the first threshold.

8. The handheld self-propelled welding torch with anti-tipping function according to claim 4, characterized in that: The wire feeding speed linkage modulation module is also equipped with a feedback deviation discrimination submodule. The feedback deviation discrimination submodule monitors the deviation between the actual wire feeding speed feedback value of the external cold wire feeder and the target wire feeding speed command value output by the wire feeding speed linkage modulation module in real time. When the absolute value of the deviation exceeds the preset deviation threshold and the duration exceeds the preset time window, it is determined that the current wire feeding speed linkage has failed and the wire feeding speed is forcibly switched to the open-loop holding mode. In the open-loop holding mode, the wire feeding speed is decoupled from the real-time speed signal of the geared drive motor (2) and the wire is continuously fed according to the preset safe wire feeding speed. At the same time, the feedback deviation discrimination submodule starts the backtracking timer and backtracks to read the median value of the wire feeding speed in the wire feeding speed history record at the time of triggering the reverse speed adjustment command. The median value is used as the replacement wire feeding speed command and output to the external cold wire feeder. The feedback deviation discrimination submodule exits the open-loop holding mode and restores the normal operation of the wire feeding speed linkage modulation module.

9. The handheld self-propelled welding torch with anti-tipping function according to claim 4, characterized in that: The control circuit is equipped with a high-frequency time base signal source. The frequency of the high-frequency time base signal source is an integer multiple of the frequency corresponding to the highest speed of the deceleration drive motor (2) and not less than 1000Hz. The determination of continuous load reduction, the linkage modulation of wire feeding speed, the determination of lateral slippage, and the conduction control of the start-up circuit share the high-frequency time base signal source and occupy time slot resources in a time-division multiplexing manner according to priority. The priority order is as follows: the determination of continuous load reduction occupies the first time slot, the linkage modulation of wire feeding speed occupies the second time slot, the determination of lateral slippage occupies the third time slot, and the conduction control of the start-up circuit occupies the fourth time slot. When the instructions output by two determinations in the same sampling period act on the same execution unit, the control circuit executes the high-priority instruction in priority order and caches the low-priority instruction to be executed in the next sampling period. A status register is also set between each determination. The status register latches the output status of each determination at the beginning of each sampling period and synchronizes the latched value to all determinations, so that each determination performs calculations based on the same set of status data in the same sampling period.

10. The handheld self-propelled welding torch with anti-tipping function according to claim 1, characterized in that: The control circuit is also equipped with a repetitive trigger suppression module. When the control circuit continuously detects that the same traveling wheel (8) experiences a continuous decrease in load and triggers a reverse speed adjustment command in three consecutive unit travel segments, and the time for the output half shaft (602) corresponding to the traveling wheel (8) to recover to a stable value after each reverse speed adjustment command is greater than a preset time threshold, the control circuit determines that there is a continuous depression or obstacle on the surface of the current workpiece. At this time, the repetitive trigger suppression module terminates the triggering of subsequent reverse speed adjustment commands and switches the output command of the reduction drive motor (2) to In slow mode, the walking speed is 30% of the normal welding speed and the speed difference between the two output half shafts (602) of the micro planetary differential (6) is forcibly locked to zero. At the same time, an alarm signal is issued through the indicator light set on the welding torch body (1). The length of the unit travel segment is equal to the circumference of the walking wheel (8) rolling once when it touches the ground. When the operator sets the mode selection switch (11) set on the welding torch body (1) to the stop position and then sets it back to the walking position, the suppression module is repeatedly triggered to reset and the normal triggering function of the reverse speed regulation command is restored.

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