Motion control method and system suitable for welding robot of large storage tank

Abstract

The invention discloses a motion control method and system suitable for a welding robot of a large storage tank. The method comprises the steps that weld joint deviation data are obtained; welding seam deviation filtering processing: judging whether deviation data filtering is started or not, and if yes, selecting a filtering algorithm; otherwise, directly inputting the deviation data into a deviation closed-loop calculation link; deviation closed-loop calculation: inputting the deviation data in the Y-axis direction and the deviation data in the Z-axis direction into a closed-loop algorithm input end, and obtaining the corresponding speed and direction of an execution mechanism according to the input deviation; the speed is obtained through calculation according to a closed-loop algorithm, the speed is transmitted to a two-dimensional motion platform, and a welding gun is controlled to conduct stable welding; and surface covering operation: judging whether surface covering is needed or not, if so, starting a timer for counting, and when the time count reaches a preset value, starting a welding gun to swing. According to the control scheme, the movable welding robot can be stably controlled to achieve horizontal welding one-time forming of the medium-thickness stainless steel plate.

Description

Technical Field

[0001] The present invention relates to the field of welding robots, and in particular to a motion control method and system for a welding robot suitable for large storage tanks. Background Art

[0002] Large stainless steel storage tanks are bulky and difficult to transport as a whole. Therefore, they must be welded and assembled on-site. Traditional industrial fixed-base welding robots are clearly unsuitable for this purpose. Mobile welding robots are ideally suited to address the labor-intensive, inefficient, and difficult nature of manual welding in outdoor environments. They offer high efficiency, high quality, and low cost, significantly reducing manual labor and ensuring uniform welding standards. However, a control solution for welding large storage tanks is currently lacking. Summary of the Invention

[0003] In order to solve one of the technical problems existing in the prior art to at least a certain extent, an object of the present invention is to provide a motion control method and system for a welding robot suitable for large storage tanks.

[0004] The first technical solution adopted by the present invention is:

[0005] A motion control method for a welding robot suitable for large storage tanks comprises the following steps:

[0006] Obtaining weld deviation data: First, obtain the Z-axis deviation data from the laser ranging module; second, determine whether the leading distance sequence of the laser tracking module is empty. If so, record the leading distance sequence of the laser tracking module; otherwise, use the leading distance sequence of the laser tracking module as the deviation data in the Y-axis direction during the mobile robot welding process;

[0007] Weld deviation filtering: Determine whether to enable deviation data filtering. If enabled, select the filtering algorithm. Otherwise, directly input the deviation data into the deviation closed-loop calculation link.

[0008] Deviation closed-loop calculation: Input the deviation data of the Y-axis direction and the deviation data of the Z-axis into the input of the closed-loop algorithm, and obtain the corresponding speed and direction of the actuator based on the input deviation;

[0009] Weld seam tracking execution: The speed is calculated based on the closed-loop algorithm, and the speed is transmitted to the two-dimensional motion platform to control the welding gun for stable welding;

[0010] Covering operation: Determine whether covering is required. If so, start the timer counting. When the time count reaches the preset value, start the TIG welding gun swing welding; otherwise skip the execution.

[0011] Furthermore, the preceding distance sequence of the laser tracking module is obtained by: acquiring deviation data of the laser tracking module using an open TCP protocol, and recording a number of points at a preset time interval to form the preceding distance sequence of the laser tracking module;

[0012] The Z-axis deviation data is obtained from a laser distance measurement module via the Modbus RTU protocol. The laser distance measurement module is located just above the welding gun.

[0013] Furthermore, the number of sequence points in the leading distance sequence of the laser tracking module is calculated as follows:

[0014]

[0015] Where L represents the distance between the laser tracking module and the welding gun; V represents the forward speed of the AGV; · represents rounding; and N represents the number of sequence points in the leading distance sequence of the laser tracking module.

[0016] Furthermore, the filtering algorithm is a median filtering algorithm, a first-order filtering algorithm or an arithmetic mean filtering algorithm;

[0017] Among them, the median filter algorithm uses 5 data points for calculation, sorts the 5 data deviation values, and takes the middle value;

[0018] The first-order filtering algorithm uses the following formula for calculation:

[0019] OUT=0.6*ERR+0.4*ERR_LAST

[0020] ERR=OUT

[0021] ERR_LAST=ERR

[0022] Where, ERR represents the current deviation, ERR_LAST represents the last deviation, and OUT represents the output value of the filtering algorithm;

[0023] The arithmetic mean filtering algorithm uses 5 data for calculation, sums the 5 data deviations, and then takes the average.

[0024] Furthermore, the closed-loop algorithm is a deviation direct closed-loop control algorithm or a PID closed-loop control algorithm;

[0025] The deviation direct closed-loop control algorithm is implemented as follows:

[0026] V=P*ERR

[0027]

[0028] The PID closed-loop algorithm is implemented as follows:

[0029] V=KP*ERR+∑KI*ERR+KD*(ERR-LAST_ERR)

[0030]

[0031] Where ERR represents the output value of the filtering algorithm, LAST_ERR represents the previous output value of the filtering algorithm, and P is the proportional magnification / reduction coefficient. |V| represents the speed of the actuator, and Dir represents the direction of the actuator's movement. When Dir is greater than 0, it indicates that the actuator moves in the positive direction of the Y axis. When Dir is less than 0, it indicates that the actuator moves in the negative direction of the Y axis.

[0032] Furthermore, if a cover process is required, the timer counts, and the counting interval is 0.05s, then the calculation formula is:

[0033]

[0034] Where X represents the distance between the TIG welding gun and the K-TIG welding gun; V represents the forward speed of the AGV; · represents rounding; N represents the timer count size;

[0035] When welding starts, when the timer count reaches the set value N, the welding gun starts to swing and the covering operation is performed; when welding is completed, the timer count starts to decrease, and when the count returns to 0, the welding gun stops swinging.

[0036] Furthermore, the motion control method further includes a weld seam identification step:

[0037] Adjust the appropriate exposure value and laser stripe power;

[0038] Acquire weld images and set a fixed ROI area;

[0039] Use Otsu algorithm to segment weld images;

[0040] Perform image smoothing and morphological processing on the segmented image: first use the median filter algorithm to smooth the segmented image, and perform opening and closing operations;

[0041] Extract the weld centerline: Use the grayscale centroid method to calculate the grayscale centroid of each column of the laser stripe, and use this line as the target straight line for extracting weld feature points;

[0042] Extract weld feature points: Use the least squares method to fit four straight lines, and find the intersection points of the four straight lines in pairs to obtain three feature points, and use the middle feature point as the weld feature point.

[0043] Furthermore, the exposure value and the laser stripe power are adjusted appropriately so that the laser stripes are clearly visible in the original image and the reflection interference is small. The exposure time is 200 and the laser power is 100.

[0044] Furthermore, the fixed ROI area is defined as the center of the ROI matrix with the center point of the image pixel coordinate as the center, ±300 pixels along the Y axis, and ±200 pixels along the X axis.

[0045] Furthermore, the convolution kernels of median filtering, opening operation, and closing operation are all 5×5.

[0046] The second technical solution adopted by the present invention is:

[0047] A motion control system for a welding robot suitable for large storage tanks, including an AGV, a floor magnetic strip, a two-dimensional motion platform, two welding guns, a cover welding swing platform, a laser tracking module, a laser ranging module, a central controller, and a welding system;

[0048] The laser tracking module is used to obtain the relative position deviation between the current welding gun and the weld;

[0049] The laser ranging module is used to obtain the relative position deviation between the gun tip of the K-Tig welding gun and the plate;

[0050] The two welding guns are used for welding the weld and the cover respectively;

[0051] The cap welding swing platform is used to swing the Tig welding gun so that the cap width reaches the standard;

[0052] The two-dimensional motion platform is used to move the two welding guns and the cover welding swing platform, so that the welding guns track the weld seam according to the deviation data of the laser tracking module and the laser ranging module and ensure the welding arc length;

[0053] The AGV trolley and floor magnetic strips are used to move the entire welding robot;

[0054] The central controller is used for communication between modules and control of each axis;

[0055] The welding system includes a K-Tig welder, a water cooler, an Ar gas cylinder, a Tig welder, and a wire feeder.

[0056] Furthermore, the laser tracking module is mainly composed of an industrial computer, an industrial camera, and a laser transmitter. The industrial computer uses the Windows 7 operating system and the CPU is Intel i7 7700.

[0057] Furthermore, the two-dimensional motion platform is mainly composed of two 1m long screw-driven slides, two 1m long ball-guided slides, a 50cm long screw-driven slide and some cutting plate parts, which can achieve a maximum speed of 50mm / s on the Y axis and 30mm / s on the Z axis.

[0058] The beneficial effects of the present invention are as follows: the control scheme provided by the present invention can stably control the mobile welding robot to realize one-time horizontal welding of medium and thick stainless steel plates, effectively solving the problems of high labor intensity, low welding efficiency, and difficult operation of manual welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following introduction is made to the drawings of the embodiments of the present invention or the related technical solutions in the prior art. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative work.

[0060] Figure 1 This is a flow chart of a motion control method for a welding robot applicable to large storage tanks in an embodiment of the present invention;

[0061] Figure 2 This is a flow chart of a weld identification algorithm according to an embodiment of the present invention;

[0062] Figure 3 This is a structural diagram of a motion control system for a welding robot suitable for large storage tanks in an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. For the step numbers in the following embodiments, they are provided only for the convenience of explanation and are not intended to limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0064] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms of "a", "said", and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. In addition, unless otherwise clearly defined, words such as setting, installing, and connecting should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0065] In the description of this application, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0066] In the description of this application, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The terms "first" and "second" are used solely to distinguish technical features and are not to be construed as indicating or implying relative importance, or as implicitly specifying the number or order of the technical features indicated.

[0067] In the description of this application, "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0068] like Figure 1 As shown, this embodiment provides a motion control method for a K-Tig welding robot for large stainless steel storage tanks. The welding robot system includes a mobile AGV, a floor magnetic strip, a two-dimensional motion platform, two welding guns, a cover welding gun swing platform, a laser tracking module, a laser ranging module, a central controller PLC, and a welding system. The method is specifically implemented as follows:

[0069] S1. Obtain weld deviation data.

[0070] Specifically, the Z-axis deviation data is first obtained from the laser ranging module; secondly, it is determined whether the leading distance sequence of the laser tracking module is empty. If it is empty, the leading distance sequence of the laser tracking module is recorded; otherwise, the leading distance sequence of the laser tracking module is used as the deviation data in the Y-axis direction during the mobile robot welding process.

[0071] As an implementation method, the number of sequence points in the leading distance sequence of the laser tracking module is calculated as follows:

[0072]

[0073] L represents the distance between the laser tracking module and the welding gun; V represents the forward speed of the AGV; · represents rounding; N represents the number of sequence points in the leading distance sequence of the laser tracking module.

[0074] As an implementation method, the Z-axis deviation data is obtained from a laser ranging module via a Modbus RTU protocol, and the laser ranging module is located directly above the welding gun.

[0075] Specifically, the steps for obtaining the Z-axis deviation data from the laser ranging module are as follows: send the 16-bit data of the 00 address register to the Modbus RTU slave 01 laser ranging module, convert the 16-bit data into a floating-point number in the form of integer data, and finally divide the floating-point number by 10.0 to obtain the Z-axis data deviation.

[0076] As an implementation method, the leading distance sequence of the laser tracking module uses an open TCP protocol to obtain the deviation data of the laser tracking module and records a number of points at intervals of 50ms to form the leading distance sequence of the laser tracking module.

[0077] Specifically, the steps for obtaining the preceding distance sequence are as follows:

[0078] A1. Use open TCP / IP protocol to establish a TCP connection with the laser tracking sensor;

[0079] A2. Turn on the laser sensor and adjust the parameters based on the original camera image and the processed weld image until the weld feature point recognition is stable.

[0080] A3. Use specific tools to complete the needle alignment of the K-Tig tungsten electrode gun to ensure that the relative position of the welding needle and the weld meets the welding standards;

[0081] A4. The PLC sends a calibration command to the laser tracker to set the current welding needle position as the position reference point of the welding process;

[0082] A5. The PLC sends a command to start the AGV forward patrol, causing the mobile robot to move forward and record several points at 50ms intervals to form the leading distance sequence of the laser tracking module. In this embodiment, the number of leading distance sequence deviation data recording points is 274.

[0083] A6. When the leading distance sequence record is completed, the PLC sends the AGV a command to stop patrolling and wait for the next operation.

[0084] S2. Weld deviation filtering algorithm.

[0085] Specifically, it is determined whether deviation data filtering is enabled. If enabled, a filtering algorithm is selected; otherwise, the deviation data is directly input into the deviation closed-loop calculation link.

[0086] In some embodiments, there are currently three main filtering algorithms: median filtering algorithm, first-order filtering algorithm, and arithmetic mean filtering algorithm.

[0087] 1) The median filter algorithm uses 5 data points for calculation, sorts the 5 data deviation values, and takes the middle value.

[0088] 2) The first-order filtering algorithm uses the following formula for calculation:

[0089] OUT=0.6*ERR+0.4*ERR_LAST

[0090] ERR=OUT

[0091] ERR_LAST=ERR

[0092] Where ERR represents the current deviation, ERR_LAST represents the last deviation, and OUT represents the output value of the filtering algorithm;

[0093] 3) The arithmetic mean filtering algorithm uses 5 data for calculation, sums the five data deviations, and then takes the average.

[0094] Regardless of whether the filtering algorithm is enabled, the following judgment will be made before the final data deviation is input into the closed-loop algorithm:

[0095]

[0096] In the formula, ERR represents data deviation, and the ABS() operator represents taking the absolute value.

[0097] S3. Deviation closed-loop calculation.

[0098] Specifically, the Y-axis and Z-axis deviation data are input into the closed-loop algorithm input terminal. Based on the input deviation, the corresponding speed and direction of the actuator are obtained. There are two main closed-loop algorithms: the deviation direct closed-loop control algorithm and the PID closed-loop control algorithm.

[0099] Among them, the deviation direct closed-loop control algorithm is implemented as follows:

[0100] V=P*ERR

[0101]

[0102] The PID closed-loop algorithm is implemented as follows:

[0103] V=KP*ERR+∑KI*ERR+KD*(ERR-LAST_ERR)

[0104]

[0105] Where ERR represents the output value of the filtering algorithm, LAST_ERR represents the previous output value of the filtering algorithm, P is the proportional magnification and reduction coefficient, |V| represents the speed of the actuator movement, and Dir represents the direction of the actuator movement. When Dir is greater than 0, it means that the actuator moves in the positive direction of the Y axis. When Dir is less than 0, it means that the actuator moves in the negative direction of the Y axis.

[0106] S4. Execute the weld tracking operation.

[0107] The speed is calculated based on the closed-loop algorithm and transmitted to the two-dimensional motion mechanism to control the welding gun to achieve stable welding. As an implementation method, the following actions need to be completed in this process:

[0108] S41, start the K-TIG welding machine, set the corresponding welding parameters, and then start the arc;

[0109] S42, the calculated speed and direction obtained by the closed-loop algorithm are transmitted to the two-dimensional motion control platform to control the welding gun to achieve the weld tracking task;

[0110] S43, PLC sends AGV forward patrol instructions to perform welding.

[0111] S5, covering operation.

[0112] Determine whether the surface needs to be covered. If so, start a timer to count. When the time is up, start the TIG welding gun to swing weld. Otherwise, skip the execution. In this embodiment, the timer count size is 312.

[0113] As an implementation method, if the cover processing and timer counting size processing are required, the default interval is 50ms, and the calculation formula is:

[0114]

[0115] Where X represents the distance between the TIG welding gun and the K-TIG welding gun; V represents the forward speed of the AGV; · represents rounding; and N represents the timer count.

[0116] S6. End.

[0117] After welding, first turn off the K-TIG welder. Secondly, if the cover is opened, the cover timer count starts to decrease. When the count value reaches 0, turn off the TIG welder and stop the AGV. The welding is now completed.

[0118] As a further preferred embodiment, Figure 2 As shown, this embodiment also provides a weld seam recognition algorithm applicable to large stainless steel storage tanks, and the specific steps are as follows:

[0119] B1. Adjust the appropriate exposure value and laser stripe power.

[0120] First, turn on the camera and laser, and adjust the appropriate exposure value and laser stripe power. Specifically, the exposure time is 200 and the laser power is 100. The best time is when a clear laser stripe outline appears and there is no large amount of laser reflection.

[0121] B2. Acquire the weld image and set a fixed ROI area.

[0122] Turn on the camera, acquire the camera image, and set a fixed ROI area. In this embodiment, the fixed ROI area is the center of the image pixel coordinate center point as the ROI matrix center, ±300 pixels along the Y axis, and ±200 pixels along the X axis.

[0123] B3. Segment the weld image.

[0124] Specifically, the Otsu algorithm is used to segment the image and separate the laser stripes from the background.

[0125] B4. Perform image smoothing and morphological processing on the segmented image: first use the median filter algorithm to smooth the segmented image, and perform opening and closing operations.

[0126] In this embodiment, the convolution kernels of the median filter, the opening operation, and the closing operation are all 5×5.

[0127] B5. Extract the weld centerline: Use the grayscale centroid method to calculate the grayscale centroid of each column of the laser stripe, and use this line as the target straight line for extracting weld feature points.

[0128] B6. Extract weld feature points: Use the least squares method to fit four straight lines and find the intersection points of the four straight lines to obtain three feature points. The middle feature point is used as the weld feature point.

[0129] like Figure 3 As shown, this embodiment also provides a hardware system suitable for a K-Tig welding robot for large stainless steel storage tanks, including:

[0130] Laser tracking module: used to obtain the relative position deviation between the current welding gun and the weld; specifically, the laser tracking module mainly consists of an industrial computer, an industrial camera, and a laser transmitter. The industrial computer uses the Windows 7 operating system and the CPU is an Intel i7 7700;

[0131] Laser ranging module: used to obtain the relative position deviation between the K-Tig gun tip and the plate;

[0132] Two welding guns: used for welding seams and capping;

[0133] Cap welding swing platform: used to swing the Tig welding gun to make the cap width reach the standard;

[0134] Two-dimensional motion platform: Used to move the two welding guns and the cover welding swing platform, allowing the welding guns to track the weld seam and ensure the welding arc length based on the deviation data of the laser tracking module and laser ranging module. Specifically, the two-dimensional motion platform mainly consists of two 1-meter-long screw-driven slides, two 1-meter-long ball-guided slides, a 50-cm-long screw-driven slide, and some cutting plate components. It can achieve a maximum speed of 50 mm / s on the Y axis and 30 mm / s on the Z axis.

[0135] AGV trolley and magnetic strip: move the entire welding robot;

[0136] Central controller (model S7-200 SMART ST40): used for communication between modules and control of each axis;

[0137] Welding system: mainly includes K-Tig welder, water cooler, Ar gas cylinder, Tig welder and wire feeder.

[0138] As an optional implementation, the central controller communicates with the AGV car via WiFi communication.

[0139] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0140] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A motion control method for a welding robot suitable for large storage tanks, characterized in that: The following steps are involved: Obtaining weld deviation data: First, obtain the Z-axis deviation data from the laser ranging module; second, determine whether the leading distance sequence of the laser tracking module is empty. If so, record the leading distance sequence of the laser tracking module; otherwise, use the leading distance sequence of the laser tracking module as the deviation data in the Y-axis direction during the mobile robot welding process; Weld deviation filtering: determine whether to enable deviation data filtering. If enabled, select the filtering algorithm. Otherwise, the deviation data is directly input into the deviation closed-loop calculation link; Deviation closed-loop calculation: Input the deviation data of the Y-axis direction and the deviation data of the Z-axis into the input of the closed-loop algorithm, and obtain the corresponding speed and direction of the actuator based on the input deviation; Weld seam tracking execution: The speed is calculated based on the closed-loop algorithm, and the speed is transmitted to the two-dimensional motion platform to control the welding gun for stable welding; Covering operation: Determine whether covering is required. If necessary, start the timer counting. When the time count reaches the preset value, start the welding gun swing.

2. The motion control method for a welding robot suitable for large storage tanks according to claim 1 is characterized in that: The preceding distance sequence of the laser tracking module is obtained by: using an open TCP protocol to obtain deviation data of the laser tracking module, and recording a number of points at a preset time interval to form the preceding distance sequence of the laser tracking module; The Z-axis deviation data is obtained from a laser distance measurement module via the Modbus RTU protocol. The laser distance measurement module is located just above the welding gun.

3. The motion control method for a welding robot suitable for large storage tanks according to claim 1 is characterized in that: The number of sequence points in the leading distance sequence of the laser tracking module is calculated as follows: Where L represents the distance between the laser tracking module and the welding gun; V represents the forward speed of the AGV; · represents rounding; and N represents the number of sequence points in the leading distance sequence of the laser tracking module.

4. The motion control method for a welding robot suitable for large storage tanks according to claim 1 is characterized in that: The filtering algorithm is a median filtering algorithm, a first-order filtering algorithm or an arithmetic mean filtering algorithm; Among them, the median filter algorithm uses 5 data points for calculation, sorts the 5 data deviation values, and takes the middle value; The first-order filtering algorithm is calculated using the following formula: OUT=0.6*ERR+0.4*ERR_LAST ERR=OUT ERR_LAST=ERR Where, ERR represents the current deviation, ERR_LAST represents the last deviation, and OUT represents the output value of the filtering algorithm; The arithmetic mean filtering algorithm uses 5 data for calculation, sums the 5 data deviations, and then takes the average.

5. The motion control method for a welding robot suitable for large storage tanks according to claim 1 is characterized in that: The closed-loop algorithm is a deviation direct closed-loop control algorithm or a PID closed-loop control algorithm; The deviation direct closed-loop control algorithm is implemented as follows: The PID closed-loop algorithm is implemented as follows: Where ERR represents the output value of the filtering algorithm, LAST_ERR represents the previous output value of the filtering algorithm, and P is the proportional magnification / reduction coefficient. |V| represents the speed of the actuator, and Dir represents the direction of the actuator's movement. When Dir is greater than 0, it indicates that the actuator moves in the positive direction of the Y axis. When Dir is less than 0, it indicates that the actuator moves in the negative direction of the Y axis.

6. The motion control method for a welding robot suitable for large storage tanks according to claim 1, characterized in that: If a cover process is required, the timer counts, and the counting interval is 0.05s. The calculation formula is: Where X represents the distance between the TIG welding gun and the K-TIG welding gun; V represents the forward speed of the AGV; · represents rounding; N represents the timer count size; When welding starts, when the timer count reaches the set value N, the welding gun starts to swing and the covering operation is performed; when welding is completed, the timer count starts to decrease, and when the count returns to 0, the welding gun stops swinging.

7. The motion control method for a welding robot suitable for large storage tanks according to claim 1, characterized in that: The motion control method further comprises a weld seam identification step: Adjust the appropriate exposure value and laser stripe power; Acquire weld images and set a fixed ROI area; Segment the weld image; Perform image smoothing and morphological processing on the segmented image: first use the median filter algorithm to smooth the segmented image, and perform opening and closing operations; Extract the weld centerline: Use the grayscale centroid method to calculate the grayscale centroid of each column of the laser stripe, and use this line as the target straight line for extracting weld feature points; Extract weld feature points: Use the least squares method to fit four straight lines, and find the intersection points of the four straight lines in pairs to obtain three feature points, and use the middle feature point as the weld feature point.

8. The motion control method for a welding robot suitable for large storage tanks according to claim 7, characterized in that: The fixed ROI area is centered on the center point of the image pixel coordinate as the center of the ROI matrix, ±300 pixels along the Y axis and ±200 pixels along the X axis; the convolution kernels of the median filter, opening operation, and closing operation are all 5×5.

9. A motion control system for a welding robot suitable for large storage tanks, characterized in that: Including AGV car, magnetic strip, two-dimensional motion platform, two welding guns, cover welding swing platform, laser tracking module, laser ranging module, central controller, welding system; The laser tracking module is used to obtain the relative position deviation between the current welding gun and the weld; The laser ranging module is used to obtain the relative position deviation between the gun tip of the K-Tig welding gun and the plate; The two welding guns are used for welding the weld and the cover respectively; The cap welding swing platform is used to swing the Tig welding gun so that the cap width reaches the standard; The two-dimensional motion platform is used to move the two welding guns and the cover welding swing platform, so that the welding guns track the weld seam according to the deviation data of the laser tracking module and the laser ranging module and ensure the welding arc length; The AGV trolley and magnetic strip are used to move the entire welding robot; The central controller is used for communication between modules and control of each axis; The welding system includes a K-Tig welder, a water cooler, an Ar gas cylinder, a Tig welder, and a wire feeder.

10. The motion control system of a welding robot suitable for large storage tanks according to claim 9, characterized in that: The two-dimensional motion platform consists of two 1-meter-long screw-driven slides, two 1-meter-long ball-guided slides, a 50-cm-long screw-driven slide and several cutting plate parts, and is used to achieve a maximum speed of 50 mm / s on the Y axis and 30 mm / s on the Z axis.

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