Laser arc hybrid welding control system

Abstract

The invention relates to the field of hybrid welding, and discloses a laser arc hybrid welding control system which comprises a welding execution unit, a laser arc welding unit and a control unit. The welding execution unit comprises a welding robot, a welding laser, an electric arc welder and a focus-adjustable composite welding head; a line laser scanning unit; the line laser scanning unit is mounted at a preset distance in front of the composite welding head; the line laser scanning unit is used for projecting line structure light in the direction of a to-be-welded weld joint and obtaining weld joint point cloud data. An external traveling shaft; the external walking shaft is used for driving the welding execution unit to move in the length direction of a welding seam; a control unit; the control unit is in communication connection with the line laser scanning unit, the welding execution unit and the external walking shaft. According to the technical scheme, the problem that a sensing point and an execution point are staggered during speed change, arcing and external walking shaft speed fluctuation of the welding robot is effectively solved.

Description

Technical Field

[0001] This application relates to the field of composite welding, and more particularly to a laser-arc composite welding control system. Background Technology

[0002] Laser-arc hybrid welding combines the advantages of laser deep penetration welding and arc welding, featuring fast welding speed and deep penetration, and is widely used in various fields.

[0003] Existing visual delay control is mostly based on time logic delay. When the welding robot changes speed, starts arcing, or encounters external walking axis speed fluctuations, time-based delay can cause misalignment between the sensing point and the execution point, resulting in welding defects.

[0004] Solving this technical problem is a technical challenge that needs to be overcome by those skilled in the art. Summary of the Invention

[0005] This application provides a laser-arc hybrid welding control system to at least partially solve the above-mentioned technical problems.

[0006] To achieve the above objectives, this application provides a laser-arc hybrid welding control system, comprising: Welding execution unit; the welding execution unit includes a welding robot, a welding laser, an arc welding machine, and a composite welding head with adjustable focus; A line laser scanning unit; the line laser scanning unit is installed at a preset distance in front of the composite welding head; the line laser scanning unit is used to project line structured light along the direction of the weld seam to be welded and acquire weld seam point cloud data; External travel axis; the external travel axis is used to drive the welding execution unit to move along the length of the weld seam; Control unit; the control unit is communicatively connected to the line laser scanning unit, the welding execution unit, and the external traveling axis; The control unit is configured to: Receive and parse the weld point cloud data sent by the line laser scanning unit; Target process parameters are generated based on the weld seam point cloud data; the target process parameters include: the motion trajectory and posture of the welding robot, the output power of the welding laser, the current and voltage of the arc welding machine, and the focal position of the composite welding head; Before the welding execution unit reaches the corresponding weld position, the target process parameters are sent to the corresponding execution module.

[0007] In this embodiment of the application, the above technical solution effectively reduces the misalignment problem between the sensing point and the execution point when the welding robot changes speed, starts arc, and experiences speed fluctuations on the external walking axis.

[0008] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a system block diagram of a laser-arc hybrid welding control system provided in an exemplary embodiment of this application. Detailed Implementation

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0012] This application provides a laser-arc hybrid welding control system. Please refer to [link / reference]. Figure 1 The laser-arc hybrid welding control system provided in this application includes: The welding execution unit comprises a welding robot, a welding laser, an arc welding machine, and an adjustable-focus composite welding head. Specifically, the welding robot is an execution device capable of moving the composite welding head with multiple degrees of freedom and adjusting its posture according to real-time control commands. Its function is to enable the composite welding head to align with the weld seam and move along the weld seam trajectory. The welding laser is the core component that provides the high-energy laser beam required for laser welding. Its output power can be adjusted according to welding requirements to achieve deep penetration welding. The arc welding machine provides the arc energy required for arc welding. By outputting controllable current and voltage, the arc welding machine generates a stable arc, thereby achieving filler welding of the weld seam. The adjustable-focus composite welding head is an execution component integrating a laser emission channel and an arc welding channel. It can adjust the position of the laser focus at the weld seam according to welding requirements, achieving coordinated operation of laser energy and arc energy.

[0013] A line laser scanning unit is installed at a preset distance in front of the composite welding head. This unit projects line structured light along the direction of the weld seam and acquires weld point cloud data. Specifically, the line laser scanning unit is a detection component integrating a line laser emitter and an image acquisition module, installed in front of the composite welding head. The line laser scanning unit scans and detects the weld seam before the welding execution unit reaches the welding position. The preset distance is a fixed distance to ensure the line laser scanning unit can complete the weld seam scan in advance and allow time for parameter calculation and transmission to the control unit. Line structured light refers to a linearly distributed laser beam that, after being projected onto the surface of the weld seam, forms light stripes of different shapes due to differences in the weld seam's contour, such as gap and bevel. Weld point cloud data refers to a dataset captured by the image acquisition module of the line laser scanning unit, consisting of the three-dimensional coordinates of various points on the weld seam surface, reflecting the actual contour, gap width, and bevel depth of the weld seam.

[0014] External travel shaft; the external travel shaft is used to drive the welding execution unit to move along the length of the weld. Specifically, the external travel shaft is a transmission mechanism that can move along a preset trajectory. By being fixedly connected to the welding execution unit, it drives the entire welding execution unit to move synchronously along the length of the weld.

[0015] Control unit; The control unit is communicatively connected to the line laser scanning unit, welding execution unit, and external travel axis; The control unit is configured as follows: Receive and parse the weld point cloud data sent by the line laser scanning unit; Target process parameters are generated based on weld point cloud data. These parameters include: the motion trajectory and posture of the welding robot, the output power of the welding laser, the current and voltage of the arc welding machine, and the focal position of the composite welding head. Specifically, the motion trajectory and posture of the welding robot refer to the path along which the robot moves the composite welding head along the weld contour, as well as the angle and height between the composite welding head and the weld surface, requiring the composite welding head to always be aligned with the weld center. The output power of the welding laser refers to the energy intensity of the laser beam, which directly affects the weld penetration and welding speed. The current and voltage of the arc welding machine are parameters that control the arc energy, determining the stability of the arc and the weld filling effect. The focal position of the composite welding head refers to the specific location where the laser beam is focused on the weld; focal adjustment can optimize the laser energy density to adapt to welding requirements with different gaps and bevels.

[0016] Before the welding execution unit reaches the corresponding weld position, the target process parameters are sent to the corresponding execution module. Specifically, the control unit calculates the time required for the welding execution unit to reach the scanned weld position from its current position based on the moving speed of the external traveling axis and the preset distance between the line laser scanning unit and the composite welding head. The generated target process parameters are sent in advance to the corresponding execution modules of the welding robot, welding laser, arc welding machine, and composite welding head. When the welding execution unit reaches the weld position, it can carry out welding operations according to the target process parameters, avoiding welding deviations caused by parameter sending delays.

[0017] Specifically, the line laser scanning unit scans the weld seam in advance and acquires point cloud data, enabling it to capture the actual features of the weld seam contour in real time. The control unit generates target process parameters based on the point cloud data analysis results, achieving the adaptation of process parameters to the actual features of the weld seam and avoiding problems such as uneven penetration and poor filling caused by preset fixed parameters. The control unit uses real-time speed combined with the calculation delay of preset spacing to replace the existing fixed time delay control, effectively reducing the misalignment problem between the sensing point and the execution point when the welding robot changes speed, starts arc, and the speed of the external walking axis fluctuates, thus reducing welding defects caused by such misalignment.

[0018] In some embodiments, generating target process parameters based on weld point cloud data includes: The control unit receives and analyzes the weld point cloud data sent by the line laser scanning unit. Specifically, the control unit receives the weld point cloud data transmitted by the line laser scanning unit, and uses a built-in point cloud data analysis algorithm to denoise and filter out invalid noise points from the original point cloud data. It then extracts valid data that reflects the actual characteristics of the weld through feature extraction. The gap width refers to the width of the gap between the two butt joints of the weld, which affects the amount of filler metal required for welding. The bevel depth refers to the vertical depth of the bevel formed by machining the workpiece, reflecting the required depth of weld penetration. The bevel cross-sectional area refers to the cross-sectional area of ​​the bevel along the direction perpendicular to the weld length, used to calculate the amount of filler metal required for welding.

[0019] The theoretical metal filling amount at the current position is calculated based on the bevel cross-sectional area. The theoretical metal filling amount refers to the total amount of metal material required to fill the bevel during the welding process to achieve complete fusion and form a qualified weld. Its calculation needs to combine the bevel cross-sectional area and welding cladding characteristics. The specific calculation formula can be: theoretical metal filling amount = bevel cross-sectional area × cladding efficiency. The cladding efficiency refers to the ratio of the actual filling metal to the theoretically calculated filling metal.

[0020] The theoretical metal filler volume is input into the built-in process database to obtain the initial process parameters. These initial parameters include the reference wire feed speed, reference laser power, and reference arc voltage. The process database is a parameter storage module within the control unit that pre-stores process parameters corresponding to different materials, plate thicknesses, and theoretical metal filler volumes. The parameters in the database undergo extensive experimental verification to ensure the basic stability of the welding process. The reference wire feed speed refers to the basic wire feed speed that meets the theoretical metal filler volume requirement, and it determines the rate of metal filling during welding. The reference laser power refers to the basic laser energy intensity required to achieve deep weld penetration. The reference arc voltage refers to the basic arc voltage required to maintain arc stability and achieve metal filling.

[0021] The initial process parameters are corrected based on the deviation between the currently extracted gap width and the standard gap. The standard gap refers to the weld gap width preset according to welding process requirements and workpiece processing standards. The standard gap is the benchmark for judging whether there is a deviation in the gap and whether the process parameters need to be corrected. Gap width deviation = currently extracted gap width - standard gap. A positive deviation indicates that the gap is too large, and a negative deviation indicates that the gap is too small. The deviation will directly lead to a difference between the actual metal filling requirement and the theoretical calculation. If it is not corrected, it will cause defects such as incomplete penetration, undercut, and poor weld formation. Therefore, the initial process parameters need to be corrected based on the deviation. The correction process is as follows: The correction ratio for the theoretical metal filling amount is calculated based on the deviation of the gap width. The target wire feeding speed is obtained by synchronously increasing or decreasing the wire feeding speed based on the reference wire feeding speed according to the correction ratio. The correction ratio is positively correlated with the gap width deviation, that is, the larger the gap deviation, the higher the correction ratio. Specifically, it can be determined through a preset mapping relationship. For example, for every 0.1mm increase in the gap deviation, the correction ratio increases by 5%-8% to ensure that the corrected theoretical metal filling amount can match the actual gap width. The target wire feeding speed = reference wire feeding speed × (1 + correction ratio). When the gap is too large, the wire feeding speed is increased, and when the gap is too small, the wire feeding speed is decreased to achieve the matching of the metal filling amount with the actual gap. Based on the energy coupling characteristics of laser and arc, the change in target wire feed speed relative to the reference wire feed speed is used as the mapping independent variable to calculate the corresponding laser power correction and arc voltage correction. The energy coupling characteristics refer to the interaction between laser energy and arc energy; they do not work independently but rather coordinate and influence each other. Changes in wire feed speed alter the metal filling rate, thus affecting the laser deep melting effect and the arc filling effect. Therefore, laser power and arc voltage need to be corrected synchronously to adapt to changes in wire feed speed. The change in target wire feed speed = target wire feed speed - reference wire feed speed. The control unit uses this change as input through a built-in energy coupling mapping model to calculate the laser power correction and arc voltage correction that maintain energy balance. The laser power correction and arc voltage correction are then superimposed on the reference laser power and reference arc voltage to obtain the target power and target voltage parameters; that is, target laser power = reference laser power + laser power correction, and target arc voltage = reference arc voltage + arc voltage correction, ensuring that the laser energy and arc energy are adapted to the actual gap width and wire feed speed.

[0022] The energy coupling mapping model is a nonlinear mapping model built into the control unit and calibrated through extensive experiments. Its core principle is to establish a correspondence between the change in wire feed speed and the correction values ​​of laser power and arc voltage based on laser and arc energy. The calibration process of the energy coupling mapping model is as follows: By changing the wire feed speed under different welding materials, plate thicknesses, and initial process parameters; collecting the optimal correction values ​​of laser power and arc voltage; using multiple sets of experimental data on the change in wire feed speed, laser power correction, and arc voltage correction as samples, and inputting them into the model for training and fitting, the nonlinear mapping relationship curve and fitting formula are obtained. The fitting formula adopts a quadratic polynomial fitting. The input parameters of the model include, in addition to the target change in wire feed speed, the deviation of the current weld gap width and the fluctuation of the bevel depth, to avoid correction deviations caused by a single change in wire feed speed, because changes in gap and bevel will also indirectly affect the energy requirements of laser and arc. The model's solution process: The control unit inputs the real-time collected changes in the target wire feed speed, gap width deviation, and bevel depth fluctuation into the calibrated energy coupling mapping model. The model first calculates the basic corrections for laser power and arc voltage based on the changes in wire feed speed using built-in fitting formulas. Then, it performs secondary fine-tuning of the basic corrections based on the gap width deviation and bevel depth fluctuation: When the gap is too large or the bevel is too deep, the arc voltage correction is appropriately increased to improve filling capacity, and the laser power correction is slightly increased to ensure melting depth; when the gap is too small or the bevel is too shallow, the arc voltage correction is appropriately decreased to avoid overfilling, and the laser power correction is slightly decreased to avoid excessive melting depth. Finally, the laser power correction and arc voltage correction are output.

[0023] The displacement compensation amount of the composite welding head in the height direction is calculated based on the fluctuation of the bevel depth, and a focusing command is generated for the composite welding head. The fluctuation of the bevel depth refers to the difference between the currently extracted bevel depth and the preset standard bevel depth; a positive fluctuation indicates a deeper bevel, and a negative fluctuation indicates a shallower bevel. The displacement compensation amount refers to the distance the composite welding head needs to move in the height direction (perpendicular to the weld surface) to ensure the laser focus of the composite welding head is always aligned with the bottom of the bevel to guarantee sufficient penetration. If the bevel is too deep, the compensation amount needs to be increased, requiring the composite welding head to move downwards; if the bevel is too shallow, the compensation amount needs to be reduced, requiring the composite welding head to move upwards. The focusing command is a control signal issued by the control unit to the focusing module of the composite welding head, used to drive the focusing mechanism of the composite welding head to adjust the laser focus position, ensuring that the laser energy can act on the target area of ​​the bevel and avoiding uneven penetration caused by bevel depth fluctuations.

[0024] The system acquires the moving speed of the external traveling axis and calculates the delay time required to reach the welding point based on the preset physical distance between the line laser scanning unit and the composite welding head. The moving speed of the external traveling axis refers to the real-time speed at which the external traveling axis drives the welding execution unit to move along the weld length direction. This speed can be collected in real time by the speed sensor of the external traveling axis and fed back to the control unit. The delay time = preset physical distance ÷ moving speed of the external traveling axis. This delay time is the time required for the composite welding head to reach the weld position scanned by the line laser scanning unit from its current position.

[0025] When the delay time arrives, the generated target process parameters are sent to the corresponding execution modules; the corresponding execution modules are the motion control module of the welding robot, the power control module of the welding laser, the electrical parameter control module of the arc welding machine, and the focusing control module of the composite welding head.

[0026] In some embodiments, the control unit is further configured to: The actual feedback speed of the external travel axis is collected; the actual feedback speed refers to the actual speed at which the external travel axis operates during the welding process. It is collected by a speed sensor installed on the external travel axis, and the collected actual feedback speed is transmitted to the control unit.

[0027] Calculate the speed deviation ratio between the actual feedback speed and the preset welding setting speed. The preset welding setting speed refers to the preset movement speed of the external travel axis based on the welding material, plate thickness, and weld type. It can be matched in the process database or manually adjusted according to the actual welding scenario. The formula for calculating the speed deviation ratio is: Speed ​​deviation ratio = (Actual feedback speed - Preset welding setting speed) ÷ Preset welding setting speed × 100%. This ratio reflects the amplitude of speed fluctuation. A positive ratio indicates that the actual speed is higher than the setting speed, and a negative ratio indicates that the actual speed is lower than the setting speed.

[0028] If the speed deviation ratio is within the preset range, the current process parameter output will be maintained. The preset range refers to the preset speed deviation ratio interval that does not require parameter correction. When the speed deviation ratio is within the preset range, it means that the speed fluctuation of the external traveling axis is small and will not have a significant impact on the weld formation cross-sectional area. At this time, the control unit does not need to adjust the process parameters and maintains the current target wire feed speed, laser power, arc voltage and other parameters unchanged to avoid welding quality fluctuations caused by unnecessary parameter adjustments, while reducing the computational load of the control unit.

[0029] If the speed deviation ratio exceeds the preset range, the target wire feed speed is corrected based on the speed deviation ratio to keep the corrected target wire feed speed synchronized with the actual feedback speed, thereby maintaining the stability of the weld formation cross-sectional area. The weld formation cross-sectional area refers to the cross-sectional area of ​​the weld along the direction perpendicular to the weld length after welding, and its size directly determines the load-bearing capacity and welding quality of the weld. Since the weld formation cross-sectional area is directly related to the wire feed speed and welding speed, when the welding speed fluctuates, if the wire feed speed remains unchanged, it will cause a deviation in the amount of metal filling per unit length of weld. If the speed increases, the filling amount will be insufficient, and if the speed decreases, the filling amount will be excessive, which will lead to an unstable weld formation cross-sectional area and defects such as incomplete penetration. The control unit corrects the target wire feed speed based on the speed deviation ratio. The correction formula is: corrected target wire feed speed = current target wire feed speed × (1 + speed deviation ratio). By correcting, the wire feed speed changes proportionally to the actual welding speed, ensuring that the amount of metal filling per unit length of weld is relatively stable, thereby maintaining the stability of the weld formation cross-sectional area. To prevent the wire feeding speed from exceeding the equipment's rated range or failing to meet process requirements after correction, the corrected target wire feeding speed must be limited to the preset wire feeding speed range. If the corrected speed exceeds this range, the control unit will clamp it to the range boundary value and simultaneously issue an alarm signal to remind staff to check the cause of the abnormal external travel axis speed.

[0030] In some embodiments, the control unit is further configured to: The system receives weld seam point cloud data sent by the line laser scanning unit and extracts the local coordinates of weld seam feature points in the sensor coordinate system. Weld seam feature points are points that characterize the key positions of the weld seam contour, extracted from the weld seam point cloud data by the control unit using a built-in point cloud feature extraction algorithm. The sensor coordinate system is a three-dimensional coordinate system established with the laser emission center of the line laser scanning unit or the center of the image acquisition lens as the origin. It is used to define the spatial position of the weld seam feature points relative to the line laser scanning unit and serves as the initial coordinate system for weld seam feature point coordinate acquisition. Local coordinates refer to the three-dimensional coordinate values ​​of the weld seam feature points in the sensor coordinate system, typically represented by the x, y, and z axes. These coordinates only reflect the relative position of the feature points with respect to the line laser scanning unit and cannot be directly used for the motion control of the welding robot.

[0031] Based on a fixed homogeneous transformation matrix between the sensor coordinate system and the composite welding head tool coordinate system obtained through pre-calibration using hand-eye calibration, the local coordinates are transformed to the composite welding head tool coordinate system. Hand-eye calibration refers to the operation of determining the relative positional relationship between the line laser scanning unit and the composite welding head through a preset calibration process, such as the nine-point calibration method. Its purpose is to establish a mapping relationship between the sensor coordinate system and the tool coordinate system. The composite welding head tool coordinate system is a three-dimensional coordinate system established with the welding center point of the composite welding head as the origin. It is used to define the spatial position of the weld feature points relative to the composite welding head and is the coordinate system connecting sensor detection and robot motion control. The homogeneous transformation matrix is ​​a 4×4 matrix used to describe the translation and rotation relationship between two three-dimensional coordinate systems. It can realize the transformation of coordinate values ​​between different coordinate systems. The fixed homogeneous transformation matrix here is only used for the transformation between the sensor coordinate system and the tool coordinate system. Its matrix parameters are determined by the hand-eye calibration results and pre-stored in the control unit.

[0032] The homogeneous transformation matrix from the tool coordinate system to the robot base coordinate system is calculated by combining the robot's real-time joint angles and the forward kinematics model. The real-time joint angles refer to the real-time rotation angles of each joint of the welding robot, which are collected in real-time by angle sensors installed at the robot joints and fed back to the control unit. The forward kinematics model is a mathematical model that calculates the spatial position and orientation of the tool coordinate system relative to the robot base coordinate system based on the welding robot's mechanical structural parameters and the known real-time angles of each joint. Its function is to convert the relative position of the tool coordinate system into a globally recognizable position for the robot. The homogeneous transformation matrix calculated here is a dynamic matrix that updates in real-time as the robot's joint angles change.

[0033] The coordinates of the weld feature points in the tool coordinate system are mapped to the robot base coordinate system through a homogeneous transformation matrix to generate the actual weld path points. The actual weld path points refer to the absolute coordinate values ​​of the weld feature points in the robot base coordinate system, which reflect the actual spatial trajectory of the weld and are different from the robot's preset trajectory.

[0034] In the robot's base coordinate system, the search point is the projection point on the robot's preset trajectory that has the closest Euclidean distance to the actual weld path point. The robot's preset trajectory refers to the theoretical welding trajectory that the welding robot should follow, which is preset in the control unit in advance. The projection point is the point on the preset trajectory that has the smallest Euclidean distance to the actual weld path point. It can be understood as the projection of the actual weld path point onto the preset trajectory, and is used to determine the deviation direction and deviation reference of the actual weld trajectory relative to the preset trajectory.

[0035] Calculate the positional deviation vector of the actual weld path point relative to the projected point; decompose the positional deviation vector into a lateral deviation component and a height deviation component, and use these two components as the deviation data to be compensated. The positional deviation vector is a three-dimensional vector originating from the projected point and ending at the actual weld path point. It not only reflects the magnitude of the deviation between the actual weld path point and the projected point (vector magnitude, i.e., Euclidean distance) but also the direction of the deviation (vector direction). The lateral deviation component is the component of the positional deviation vector perpendicular to the weld length, reflecting the horizontal deviation of the composite weld joint relative to the weld center; the height deviation component is the component of the positional deviation vector perpendicular to the weld surface, reflecting the vertical deviation of the composite weld joint relative to the weld center; the deviation data to be compensated is the combination of the lateral and height deviation components.

[0036] A first-in-first-out (FIFO) correction queue is constructed, containing position index labels and deviation data. The FIFO correction queue is a data storage queue that follows the principle of "first-in, first-out," used to orderly store the deviation data to be compensated and its corresponding trigger positions. This ensures that deviation compensation is performed sequentially according to the weld welding order, avoiding misalignment of deviation compensation. The position index label identifies the welding position where the compensation operation should be performed; here, it specifically refers to the subsequent trigger position index. The deviation data refers to the deviation data to be compensated mentioned earlier: the lateral deviation component and the height deviation component. Each element in the queue is a combination of the position index label and the deviation data.

[0037] The current position index is obtained by acquiring the cumulative path length already traveled by the robot along the welding path at the current moment. The preset physical distance between the line laser scanning unit and the composite welding head is superimposed on the current position index to obtain the trigger position index where the deviation data to be compensated should be executed in the future. The deviation data to be compensated and the trigger position index are associated and packaged into a correction queue. The cumulative path length refers to the total length actually traveled by the welding robot along the welding path from the start of welding to the current moment, which is calculated in real time by the control unit in conjunction with the external walking axis speed and robot joint motion data. The current position index, i.e., the position identifier corresponding to the cumulative path length, is used to characterize the current welding position. Since the line laser scanning unit scans the weld seam in advance, the composite welding head needs a certain period of time to reach the scanned position; therefore, this distance needs to be superimposed on the current position index to obtain the trigger position index. The trigger position index refers to the welding position where the deviation data to be compensated should be executed. When the robot's cumulative path length reaches this index, the corresponding deviation compensation operation is triggered, ensuring that the timing of deviation compensation matches the welding position and avoiding compensation that is too early or too late. The two are associated and packaged into a correction queue to achieve orderly storage of the data to be compensated.

[0038] The control unit generates motion commands based on a preset trajectory and monitors the robot's real-time cumulative path length. When the real-time cumulative path length reaches the trigger position index of the first element in the correction queue, it retrieves the corresponding deviation data to be compensated. The lateral and height deviation components contained in the deviation data to be compensated are superimposed on the motion command in real time, driving the composite welding head to perform compensating motion to align the composite welding head with the weld center. When the real-time cumulative path length reaches the trigger position index of the first element, it indicates that the composite welding head has reached the welding position that needs compensation. At this time, the control unit retrieves the corresponding deviation data to be compensated from the correction queue and removes the element from the queue. The lateral and height deviation components are superimposed on the motion command, that is, the position parameters in the original motion command are finely adjusted so that the composite welding head moves the distance of the corresponding deviation component in the lateral and height directions based on the original preset trajectory to achieve compensating motion. The purpose of the compensating motion is to eliminate the deviation between the actual weld trajectory and the preset trajectory, ensuring that the welding center point of the composite welding head is always aligned with the weld center, and avoiding incomplete penetration, undercut, and weld offset caused by trajectory deviation.

[0039] In some embodiments, when correcting the target wire feed speed based on the speed deviation ratio, a line energy nonlinearity compensation operation is performed to compensate for the impact of speed fluctuations on the laser welding line energy, ensuring the stability of the laser power density during welding and avoiding welding defects caused by speed fluctuations. The control unit is also configured to: When correcting the target wire feed speed based on the speed deviation ratio, nonlinear compensation of line energy is performed. Nonlinear compensation of line energy refers to the operation of fine-tuning the laser power using nonlinear correction logic to address abnormal changes in weld line energy caused by fluctuations in the speed of the external travel axis during welding. This ensures that the laser power density acting on the weld area is always maintained within a reasonable range, especially for compensating for line energy loss when the actual feedback speed decreases. The speed deviation ratio here refers to the degree of deviation between the actual feedback speed of the external travel axis and the preset welding setting speed, as mentioned earlier. The target wire feed speed correction is based on this speed deviation ratio to keep the corrected target wire feed speed synchronized with the actual feedback speed of the external travel axis, ensuring a constant amount of weld metal filling per unit length.

[0040] Line energy nonlinear compensation includes: calling a preset nonlinear compensation index, performing a power operation with the speed deviation ratio as the base and the nonlinear compensation index as the exponent, to generate a laser power correction factor. The nonlinear compensation index is a fixed index parameter pre-stored in the control unit's process database and calibrated through extensive testing. It can be adapted to the welding material and plate thickness to ensure that the laser power correction amplitude matches the line energy changes caused by speed fluctuations. This avoids both insufficient compensation failing to resolve line energy anomalies and overcompensation causing new welding defects. The laser power correction factor is a coefficient used to adjust the laser power, and its value is always greater than 0: when the speed deviation ratio is positive (i.e., the actual feedback speed is higher than the preset welding speed), the correction factor is less than 1, used to moderately reduce the laser power to avoid excessive line energy leading to weld burn-off and undercut; when the speed deviation ratio is negative (i.e., the actual feedback speed is lower than the preset welding speed), the correction factor is greater than 1, used to moderately increase the laser power to compensate for insufficient line energy. The change amplitude of the correction factor increases nonlinearly with the increase of the absolute value of the speed deviation ratio, achieving adaptive compensation intensity.

[0041] The laser power correction factor is multiplied by the current target laser power to obtain the adjusted laser power command value. The current target laser power refers to the laser power parameters generated by the control unit before the nonlinear compensation operation is initiated, adapted to the current weld characteristics and wire feed speed. The adjusted laser power command value is the final power control command issued by the control unit to the welding laser after nonlinear compensation correction, ensuring that the laser power can adapt to fluctuations in the external travel axis speed in real time, thereby maintaining the stability of the weld line energy. For example, when the actual feedback speed of the external travel axis decreases, with a speed deviation ratio of -10% (i.e., the actual speed is 90% of the preset welding speed), and the nonlinear compensation index is 0.7, the calculated laser power correction factor is approximately 1.08. In this case, the adjusted laser power = current target laser power × 1.08. By appropriately increasing the laser power, the line energy loss caused by the speed reduction is compensated.

[0042] By adjusting the laser power command value, the output of the welding laser is controlled to ensure that the laser power density acting on the weld is always not lower than the critical threshold of the keyhole effect when the actual feedback speed is reduced, thus avoiding insufficient penetration or welding failure due to speed fluctuations.

[0043] In some embodiments, in the correction queue: When newly generated data to be compensated for is enqueued, if the queue is already full, the oldest element at the tail of the queue is discarded. A timestamp is appended to each element in the queue. If an element has not been triggered within a preset time limit since it was enqueued, the element is cleared and a timeout event is logged.

[0044] In some embodiments, when the control unit drives the composite welding head to perform compensating motion, it uses a PID control algorithm to adjust the joint angles of the welding robot in real time according to the lateral deviation component and the height deviation component.

[0045] In some embodiments, when extracting gap width, bevel depth and bevel cross-sectional area based on weld point cloud data, the weld point cloud data is first preprocessed; the preprocessing includes Gaussian filtering for noise reduction, point cloud registration and edge extraction.

[0046] In some embodiments, the communication connection between the control unit and the line laser scanning unit, the welding execution unit and the external travel axis adopts the industrial real-time Ethernet bus protocol.

[0047] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0048] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0049] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0050] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A laser-arc hybrid welding control system, characterized in that, include: Welding execution unit; the welding execution unit includes a welding robot, a welding laser, an arc welding machine, and a composite welding head with adjustable focus; A line laser scanning unit; the line laser scanning unit is installed at a preset distance in front of the composite welding head; the line laser scanning unit is used to project line structured light along the direction of the weld seam to be welded and acquire weld seam point cloud data; External travel axis; the external travel axis is used to drive the welding execution unit to move along the length of the weld seam; Control unit; the control unit is communicatively connected to the line laser scanning unit, the welding execution unit, and the external traveling axis; The control unit is configured to: Receive and parse the weld point cloud data sent by the line laser scanning unit; Target process parameters are generated based on the weld seam point cloud data; the target process parameters include: the motion trajectory and posture of the welding robot, the output power of the welding laser, the current and voltage of the arc welding machine, and the focal position of the composite welding head; Before the welding execution unit reaches the corresponding weld position, the target process parameters are sent to the corresponding execution module.

2. The system according to claim 1, characterized in that, Target process parameters are generated based on the weld point cloud data, including: Receive weld point cloud data sent by the line laser scanning unit; extract the gap width, bevel depth, and bevel cross-sectional area of ​​the current welding position based on the weld point cloud data; The theoretical metal filling amount at the current location is calculated based on the bevel cross-sectional area. The theoretical metal filling amount is input into the built-in process database to obtain the initial process parameters; the initial process parameters include the reference wire feed speed, the reference laser power, and the reference arc voltage. The initial process parameters are corrected based on the deviation between the currently extracted gap width and the standard gap. Specifically, the correction ratio for the theoretical metal filling amount is calculated based on the gap width deviation, and the target wire feeding speed is obtained by synchronously increasing or decreasing the wire feeding speed based on the reference wire feeding speed according to the correction ratio. Using the energy coupling characteristics of laser and arc, the change in the target wire feeding speed relative to the reference wire feeding speed is used as the mapping variable to calculate the corresponding laser power correction and arc voltage correction. The laser power correction and arc voltage correction are then superimposed on the reference laser power and reference arc voltage to obtain the target power and target voltage parameters. The displacement compensation amount of the composite welding head in the height direction is calculated based on the fluctuation amount of the bevel depth, and a focusing command is generated for the composite welding head. The moving speed of the external walking axis is obtained, and the delay time required to reach the welding point is calculated based on the preset physical distance between the line laser scanning unit and the composite welding head. When the delay time arrives, the generated target process parameters are sent to the corresponding execution modules.

3. The system according to claim 2, characterized in that, The control unit is also configured to: Collect the actual feedback speed of the external travel axis; calculate the speed deviation ratio between the actual feedback speed and the preset welding setting speed; If the speed deviation ratio is within the preset range, the current process parameter output is maintained; If the speed deviation ratio exceeds the preset range, the target wire feeding speed is corrected based on the speed deviation ratio so that the corrected target wire feeding speed is synchronized with the actual feedback speed to maintain the stability of the weld formation cross-sectional area.

4. The system according to claim 3, characterized in that, The control unit is also configured to: The system receives weld point cloud data sent by the line laser scanning unit and extracts the local coordinates of weld feature points in the sensor coordinate system. Based on a fixed homogeneous transformation matrix between the sensor coordinate system and the composite welding head tool coordinate system obtained through pre-calibration by hand and eye, the local coordinates are transformed to the tool coordinate system of the composite welding head. The homogeneous transformation matrix from the tool coordinate system to the robot base coordinate system is calculated by combining the robot's real-time joint angles and positive kinematics model. The coordinates of the weld feature points in the tool coordinate system are mapped to the robot base coordinate system through the homogeneous transformation matrix to generate actual weld path points. In the robot's base coordinate system, search for the projection point on the robot's preset trajectory that has the closest Euclidean distance to the actual weld path point; Calculate the positional deviation vector of the actual weld path point relative to the projected point; decompose the positional deviation vector into a lateral deviation component and a height deviation component, and use the lateral deviation component and the height deviation component as deviation data to be compensated; Construct a first-in-first-out correction queue containing position index labels and deviation data; obtain the cumulative path length that the robot has traveled along the welding path at the current moment as the current position index; superimpose the preset physical distance between the line laser scanning unit and the composite welding head onto the current position index to obtain the trigger position index where the deviation data to be compensated should be executed in the future; associate the deviation data to be compensated with the trigger position index, package it, and store it in the correction queue; The welding robot is controlled to generate motion commands based on the preset trajectory and the real-time cumulative path length of the robot is monitored in real time. When the real-time cumulative path length reaches the trigger position index of the first element of the correction queue, the deviation data to be compensated corresponding to the first element is retrieved. The lateral deviation component and the height deviation component contained in the deviation data to be compensated are superimposed into the motion command in real time, and the composite welding head is driven to perform compensation motion so that the composite welding head is aligned with the center of the weld.

5. The system according to claim 4, characterized in that, The control unit is also configured to: When correcting the target wire feed speed based on the speed deviation ratio, linear energy nonlinear compensation is performed; the linear energy nonlinear compensation includes: calling a preset nonlinear compensation index to perform a power operation with the speed deviation ratio as the base and the nonlinear compensation index as the exponent to generate a laser power correction factor; The adjusted laser power command value is obtained by multiplying the laser power correction factor by the current target laser power. By adjusting the laser power command value, the output of the welding laser is controlled to ensure that, under the condition of reduced actual feedback speed, the laser power density acting on the weld is always not lower than the critical threshold of the keyhole effect, thus avoiding insufficient penetration or welding failure due to speed fluctuations.

6. The system according to claim 5, characterized in that, In the correction queue: When newly generated data to be compensated for is enqueued, if the queue is already full, the oldest element at the tail of the queue is discarded. A timestamp is appended to each element in the queue. If an element has not been triggered within a preset time limit since it was enqueued, the element is cleared and a timeout event is logged.

7. The system according to claim 6, characterized in that, When the control unit drives the composite welding head to perform compensating motion, it uses a PID control algorithm to adjust the joint angles of the welding robot in real time according to the lateral deviation component and the height deviation component.

8. The system according to claim 7, characterized in that, When extracting gap width, bevel depth, and bevel cross-sectional area based on weld point cloud data, the weld point cloud data is first preprocessed; the preprocessing includes Gaussian filtering for noise reduction, point cloud registration, and edge extraction.

9. The system according to claim 8, characterized in that, The communication connection between the control unit and the line laser scanning unit, the welding execution unit and the external traveling axis adopts the industrial real-time Ethernet bus protocol.

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