A mobile welding robot welding system and method based on digital twin

Abstract

The present invention discloses a mobile welding robot welding system and method based on digital twin, which relates to the technical field of welding robots; the welding system includes: a physical entity system, an electric control system, a data transmission system, and a digital twin system; the physical entity system includes a welding robot physical entity and an L-shaped welding workpiece physical entity; the digital twin system includes a welding robot virtual model, an L-shaped welding workpiece virtual model, a motion monitoring interface, a coordinate acquisition module, and a collision trigger module; the electric control system is used to control the power supply and motion state of the welding robot physical entity; the data transmission system is used to upload the motion state data collected by the electric control system to the digital twin system. The present invention uses the real-time synchronous mapping of the welding robot virtual model to the physical entity of the welding robot, simplifies the control system of the welding robot, improves the positioning accuracy of the welding starting point, and assists the operator to remotely monitor the welding robot to complete the welding task.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding robots, and in particular relates to a welding system and method of a mobile welding robot based on digital twins. Background Art

[0002] Welding is called the "tailor" of the manufacturing industry and is an indispensable technology in industrial manufacturing. At present, the task of steel structure welding is heavy, and the application scenarios of traditional large-scale six-axis robotic arm welding robots are limited. For steel structure welding, the main method is still manual welding, which greatly affects the progress of welding tasks. Therefore, a small mobile welding robot is needed to solve this problem.

[0003] At present, although many mobile welding robots are put into use, these mobile welding robots have many shortcomings. These shortcomings are mainly reflected in the following aspects:

[0004] Before welding, the welding starting point needs to be located to improve the welding quality. At present, mobile welding robots mainly use two methods for positioning. One is to install a high-precision laser vision sensor system. The sensor system has a large structure and high cost, which is suitable for medium and large welding robots. The other is to design a high-voltage contact positioning system, which uses the contact between the welding wire and the workpiece to generate a voltage signal, which is fed back to the robot controller to move the welding gun a specific distance. This system requires the design of a high-voltage signal detection circuit connected to the robot main controller, which not only increases the difficulty of robot control, but also has certain risks.

[0005] At the same time, during the welding process, the weld tracking function of the current mobile welding robot not only increases the complexity of the robot, but also the tracking algorithm is relatively complex. In addition, during the welding process, workers are required to observe the welding quality on site, which will undoubtedly cause damage to the workers' bodies.

[0006] In addition, limit control is required during the welding process. The current mobile welding robot mainly uses a cross slider combination as the welding gun adjustment mechanism. Due to the design requirements of the mechanical structure, limit switches must be installed at both ends of the slide rail of the cross slider combination. According to the structure of the mobile welding robot, four limit switches need to be installed, and a circuit needs to be designed for the limit switches, which not only increases the cost, but also increases the complexity of the robot control system.

[0007] A digital twin is a digital model of a physical object. The model can evolve in real time by receiving data from the physical object and feeding the results back to the physical object, thereby helping the physical object to make rapid optimization and decisions. Deep integration can be achieved by relying on physical objects, digital twins, and information-physical systems based on digital twins. At present, in the field of industrial manufacturing, robot processing technology based on digital twins has been applied, but it is mainly through the construction of a digital twin simulation platform, the establishment of a digital model of the physical object in the digital twin simulation platform, and the acquisition of the real parameters of some or all physical objects in the current processing scene, and then the use of the digital twin simulation platform to predict the processing process of the physical object, so as to adjust the robot's trajectory during the actual processing process. Although the digital twin technology is also applied to improve the robot processing effect, the robot still needs to use traditional methods to locate the welding starting point and limit control, and the robot structure has not been effectively improved.

[0008] The present invention proposes a welding system and method for a mobile welding robot based on digital twins, and applies digital twins to the structural design of the mobile welding robot. By using the virtual to control the real, there is no need to use the robot structure to locate the welding starting point and limit control, etc., which can optimize the robot structure, improve the accuracy of welding starting point positioning, and increase the safety of operation. Summary of the invention

[0009] The purpose of the present invention is to provide a mobile welding robot welding system and method based on digital twins, so as to solve the problems that when the mobile welding robot in the prior art proposed in the above background technology realizes functions such as welding starting point positioning and welding gun limit control, the robot structure becomes complicated and the robot control difficulty increases.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A mobile welding robot welding system based on digital twin, comprising: a physical entity system, an electric control system, a data transmission system, and a digital twin system;

[0012] A physical entity system, including a welding robot physical entity and an L-shaped welding workpiece physical entity;

[0013] Digital twin system, including welding robot virtual model, L-shaped welding workpiece virtual model, motion monitoring interface, coordinate acquisition module, and collision trigger module;

[0014] The motion monitoring interface is provided with an information bar for displaying the motion state of the physical entity of the welding robot and a control button for controlling the motion state of the physical entity of the welding robot;

[0015] The coordinate acquisition module uses transform.position to obtain the coordinate values ​​of the welding robot virtual model and the L-shaped welding workpiece virtual model, which is used to control the limit, reset, horizontal position compensation and fault identification of the physical entity of the welding robot during the welding process;

[0016] The collision trigger module uses a collision function to trigger the contact between the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece, so as to control the physical entity of the welding robot to locate the welding starting point;

[0017] The electronic control system is used to collect the motion state data of the physical entity of the welding robot and feed it back to the data transmission system, and receive instructions to control the power supply and motion state of the physical entity of the welding robot;

[0018] The data transmission system is used to upload the motion state data collected by the electronic control system to the digital twin system, and to send the instructions of the digital twin system to the electronic control system.

[0019] Preferably, the welding robot physical entity includes a mobile chassis physical entity, a welding gun vertical adjustment mechanism physical entity, a welding gun horizontal adjustment mechanism physical entity, a welding gun swing mechanism physical entity, and a welding gun physical entity; a first ultrasonic sensor and a second ultrasonic sensor are installed on one side of the mobile chassis physical entity close to the L-shaped welding workpiece physical entity;

[0020] The welding robot virtual model includes a mobile chassis virtual model, a welding gun vertical adjustment mechanism virtual model, a welding gun horizontal adjustment mechanism virtual model, a welding gun swing mechanism virtual model, and a welding gun virtual model.

[0021] Preferably, a collision body component and a rigid body component are installed on the welding gun virtual model, and a collision body component is installed on the L-shaped welding workpiece virtual model; when the welding gun virtual model and the L-shaped welding workpiece virtual model come into contact, a collision function can be triggered to locate the welding starting point of the welding gun physical entity.

[0022] The mobile welding robot welding method based on digital twinning using the mobile welding robot welding system comprises the following steps:

[0023] S1, real-time synchronous mapping of the physical entity system to the digital twin system;

[0024] S2. The digital twin system controls the physical entity system to locate the welding starting point. The digital twin system sets the welding starting point of the physical entity of the welding gun based on the process target wire extension amount of the physical entity of the welding gun.

[0025] S3. The physical entity of the welding gun starts the welding process based on the positioning of the welding starting point. The digital twin system automatically tracks the weld during the welding process, and updates the relative position and motion state of the virtual model of the welding gun and the virtual model of the L-shaped welding workpiece in real time. When the weld is automatically tracked, the digital twin system controls the physical entity system to perform horizontal position compensation, limit and fault identification processing on the physical entity of the welding gun;

[0026] S4. The physical entity of the welding gun ends the welding process, and the digital twin system controls the physical entity system to reset the physical entity of the welding gun.

[0027] Preferably, in S1, the physical entity system is synchronously mapped to the digital twin system in real time, as follows:

[0028] S1-1. Establish a welding robot virtual model and an L-shaped welding workpiece virtual model in Unity according to the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece;

[0029] S1-2, controlling the relative position of the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece and the relative position of the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece to be consistent;

[0030] S1-3, control the welding robot virtual model and the welding robot physical entity to maintain the same motion state.

[0031] Preferably, the digital twin system in S2 controls the physical entity system to locate the welding starting point, as follows:

[0032] S2-1. The wire extension amount of the physical entity of the welding gun is set to zero, and the wire extension amount of the virtual model of the welding gun is set to the process target wire extension amount; and the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are controlled to be in a relatively parallel state, and the digital twin system synchronously maps the motion state of the physical entity system in real time;

[0033] S2-2, in the physical entity system, the physical entity of the welding gun is controlled to move toward the vertical surface of the physical entity of the L-shaped welding workpiece, and in the digital twin system, the virtual model of the welding gun is synchronously moved toward the vertical surface of the virtual model of the L-shaped welding workpiece in real time; if the virtual model of the welding gun contacts the vertical surface of the virtual model of the L-shaped welding workpiece, the digital twin system triggers the collision function, and the digital twin system sends a command to control the physical entity of the welding gun to stop moving forward and return a certain distance d3;

[0034] S2-3, similarly, the physical entity of the welding gun moves toward the horizontal plane of the physical entity of the L-shaped welding workpiece. If the virtual model of the welding gun contacts the horizontal plane of the virtual model of the L-shaped welding workpiece, the digital twin system triggers the collision function, and the digital twin system sends a command to control the physical entity of the welding gun to stop moving forward and then return to a distance d4 equal to d3;

[0035] S2-4. Set the welding wire extension amount of the physical entity of the welding gun to the process target welding wire extension amount.

[0036] Preferably, the digital twin system in S3 controls the physical entity system to perform horizontal position compensation of the physical entity of the welding gun, as follows:

[0037] A-1. After positioning the welding starting point, the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are in a relatively parallel state; in the digital twin system, transform.position is used to obtain the coordinate value x1 of the X-axis of the welding gun virtual model in the parallel state, and the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor are uploaded to the digital twin system;

[0038] A-2. Determine whether the physical entity of the welding robot is in a relatively parallel state with the physical entity of the L-shaped welding workpiece by using the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor; if the measurement value of the first ultrasonic sensor is not equal to the measurement value of the second ultrasonic sensor, calculate the deflection angle between the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece, and deflect the virtual model of the welding robot by the deflection angle in the digital twin system;

[0039] A-3. The digital twin system uses transform.position to obtain the coordinate value x2 of the X-axis of the virtual model of the welding gun, calculates the difference between x1 and x2, and converts it into corresponding control instructions. The digital twin system sends instructions to the electronic control system, so that the physical entity of the welding gun horizontal adjustment mechanism drives the physical entity of the welding gun to perform position compensation.

[0040] Furthermore, when the digital twin system in S3 performs automatic tracking of the weld during the welding process, it can control the physical entity of the welding gun to adjust the precision of the position compensation in the horizontal direction through the motion monitoring interface; specifically as follows:

[0041] The relative position of the physical entity of the welding gun and the physical entity of the L-shaped welding workpiece is observed through the information bar, and whether the physical entity of the welding robot deviates from the physical entity of the L-shaped welding workpiece is observed; the control instructions are input through the control buttons in the motion monitoring interface, and the digital twin system sends instructions to the electronic control system to adjust the physical entity of the welding gun horizontal adjustment mechanism to drive the physical entity of the welding gun to move. Compensation speed.

[0042] Preferably, in S3, the digital twin system controls the physical entity system to limit the physical entity of the welding gun, as follows:

[0043] B-1. Use transform.position in the digital twin system to obtain the coordinates of the moving bodies in the virtual models of the welding gun horizontal adjustment mechanism and the welding gun vertical adjustment mechanism;

[0044] B-2. Calculate the distance between the coordinates of the moving body and the two ends of the set moving trajectory. If the distance value is less than or equal to the set limit distance, the digital twin system sends a command to the electronic control system to stop the moving body in the physical entity of the welding gun horizontal adjustment mechanism and the physical entity of the welding gun vertical adjustment mechanism, thereby achieving the limit of the physical entity of the welding gun.

[0045] Preferably, in S3, the digital twin system controls the physical entity system to perform fault identification processing of the physical entity of the welding gun, specifically as follows:

[0046] C-1. In the digital twin system, a bool value is set to determine whether the physical entity of the welding robot is in motion; if the bool value is equal to true, it means that the physical entity of the welding robot is in motion; if the bool value is equal to false, it means that the physical entity of the welding robot is in a stationary state;

[0047] C-2. When the bool value is equal to true, the digital twin system uses transform.position to obtain the coordinate value of the virtual model of the welding robot. If the coordinate value of the virtual model of the welding robot does not change, the physical entity of the welding robot fails; the digital twin system sends instructions to the electronic control system to control the physical entity of the welding gun to stop welding.

[0048] Preferably, in S4, the digital twin system controls the physical entity system to reset the physical entity of the welding gun, specifically as follows:

[0049] S4-1. In the digital twin system, transform.position is used to obtain the coordinates of the moving bodies in the virtual models of the welding gun horizontal adjustment mechanism and the welding gun vertical adjustment mechanism;

[0050] S4-2. Calculate the difference between the coordinates of the moving body and the coordinates of the initial position of the moving body. The digital twin system sends instructions to the electronic control system to move the moving body in the physical entity of the welding gun horizontal adjustment mechanism and the physical entity of the welding gun vertical adjustment mechanism again, and move the moving body to the starting position to achieve the resetting of the physical entity of the welding gun.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) Use digital twin technology to locate the welding starting point, avoiding the need to set up a high-voltage contact signal detection circuit due to the use of high-voltage positioning, which not only increases the complexity of the welding robot, but also poses a safety hazard;

[0053] (2) Using digital twin technology, during the process of automatic weld tracking, position compensation is set for the physical entity of the welding gun in the horizontal direction; by obtaining the coordinate value of the X-axis of the virtual model of the welding gun, the physical entity of the horizontal adjustment mechanism of the welding gun is controlled to drive the physical entity of the welding gun to perform horizontal position compensation;

[0054] Furthermore, the acceleration and deceleration buttons on the motion monitoring interface can be used to control the movement of the physical entity of the welding gun horizontal adjustment mechanism, and then the position compensation speed of the physical entity of the welding gun can be adjusted. Compared with the traditional mobile welding robot that does not have the function of adjusting the compensation speed, the data information in the status bar can be used to improve the compensation accuracy through manual operation, which can improve the accuracy of weld tracking.

[0055] (3) By using digital twin technology, the operation of the welding gun adjustment mechanism can be limited during the automatic tracking of the weld, avoiding the use of multiple limit switches, which not only increases the cost but also increases the complexity of the welding robot control system;

[0056] (4) Using digital twin technology, the welding robot can automatically stop welding during the automatic tracking of the weld. This function can be used to determine whether the welding robot has a fault. If the welding robot has a fault, it will automatically stop welding to reduce losses;

[0057] (5) By using digital twin technology, during the automatic tracking of welds, the welding process of the welding robot can be understood by observing the motion state of the welding robot's virtual model. The motion state of the welding robot can be remotely monitored in real time, and the operator does not have to observe the welding process on site, thus reducing human injuries. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a system block diagram of a mobile welding robot welding system based on digital twin in the present invention;

[0059] Figure 2 An interface image of a digital twin system in a mobile welding robot welding system based on digital twin in the present invention;

[0060] Figure 3 This is a flow chart of locating the welding starting point of a welding method for a mobile welding robot based on digital twin in the present invention. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Embodiment 1:

[0063] See also Figure 1-2 , the mobile welding robot welding system based on digital twin includes: physical entity system, electronic control system, data transmission system, digital twin system; among which:

[0064] The physical entity system includes a welding robot physical entity and an L-shaped welding workpiece physical entity; the welding robot physical entity is composed of a mobile chassis physical entity, a welding gun vertical adjustment mechanism physical entity, a welding gun horizontal adjustment mechanism physical entity, a welding gun swing mechanism physical entity, and a welding gun physical entity; a first ultrasonic sensor and a second ultrasonic sensor are installed on one side of the mobile chassis physical entity close to the L-shaped welding workpiece physical entity.

[0065] The digital twin system includes a welding robot virtual model, an L-shaped welding workpiece virtual model, and a motion monitoring interface; the welding robot virtual model includes a mobile chassis virtual model, a welding gun vertical adjustment mechanism virtual model, a welding gun horizontal adjustment mechanism virtual model, a welding gun swing mechanism virtual model, and a welding gun virtual model; the motion control interface is provided with an information bar displaying the motion status of the physical entity of the welding robot; the motion control monitoring interface is provided with control buttons for controlling the motion status of each component of the physical entity of the welding robot.

[0066] The electronic control system is used to control the power supply and motion state of each component of the physical entity of the welding robot, and collect the motion state data of the physical entity of the welding robot and feed it back to the data transmission system.

[0067] The data transmission system is used to upload the motion status data collected by the electronic control system to the digital twin system; in addition, it is also used to transmit the instructions issued by the digital twin system to the electronic control system.

[0068] Specifically in this embodiment, the motion state data includes the displacement of the physical entity of the mobile chassis, the displacement of the physical entity of the welding gun vertical adjustment mechanism, the displacement of the physical entity of the welding gun horizontal adjustment mechanism, the swing amount of the physical entity of the welding gun swing mechanism, the measurement value of the first ultrasonic sensor, and the measurement value of the second ultrasonic sensor.

[0069] The mobile welding robot welding method based on digital twins is performed by using the mobile welding robot welding system. The mobile welding robot welding method based on digital twins can remotely monitor the entire welding process. The mobile welding robot welding method based on digital twins specifically includes the following steps:

[0070] Step 1: Based on virtual-real synchronization technology, the real-time synchronous mapping of the welding robot virtual model to the physical entity of the welding robot is realized; the details are as follows:

[0071] Step 1-1: establishing a welding robot virtual model and an L-shaped welding workpiece virtual model according to the welding robot physical entity and the L-shaped welding workpiece physical entity;

[0072] Specifically, in this embodiment, according to the actual size of the physical entity of the welding robot, SolidWorks is used to establish a three-dimensional model of the physical entity of the welding robot, and then the three-dimensional model is imported into PixyzStudio, and the parent-child relationship between the components is established according to the structure of the physical entity of the welding robot, and then the format of the three-dimensional model is changed to fbx, and then imported into Blender for rendering and assigning materials, and finally imported into Unity to become a virtual model of the welding robot; then according to the size of the physical entity of the L-shaped welding workpiece, an L-shaped welding workpiece virtual model is created in Unity.

[0073] Step 1-2: Control the relative position of the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece to be consistent with the relative position of the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece;

[0074] Specifically in this embodiment, before welding, the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are placed in appropriate positions according to the welding process requirements, and then the digital twin system is run in Unity, and a control instruction is sent to start the first ultrasonic sensor and the second ultrasonic sensor. The electronic control system collects the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor, and uploads them to the digital twin system through the data transmission system. In the digital twin system, a program is written in C#, and the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor are assigned to the virtual model of the welding robot, so that the relative position of the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece is consistent with the relative position of the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece.

[0075] Step 1-3: Control the welding robot virtual model and the welding robot physical entity to maintain the same motion state;

[0076] Specifically, in this embodiment, after completing steps 1-2, relevant instructions are sent in the digital twin system to start the operation of the physical entity of the welding robot. At the same time, the operation data generated by the physical entity of the welding robot is collected through the electronic control system, and the operation data is uploaded to the digital twin system through the data transmission system. In the digital twin system, C# is used to write a program (add identifiers and terminators to the uploaded data, such as "Axxxx / ", where A is the identifier of the first array and " / " is the terminator; the digital twin system determines which component of the physical entity system the group of data comes from by identifying the identifier), and the operation data is assigned to the virtual model of the welding robot, and then the transform.Translate() function or the transform.Rotate() function is used to drive the virtual model of the welding robot and the physical entity of the welding robot to maintain the same motion state. In this way, the real-time synchronous mapping of the virtual model of the welding robot to the physical entity of the welding robot is realized, and the user can know the motion state of the physical entity of the welding robot through the motion state of the virtual model of the welding robot in the motion monitoring interface.

[0077] Step 2: Read Figure 3 , the physical entity of the welding robot uses digital twin technology to locate the welding starting point; the details are as follows:

[0078] Step 2-1: Set the wire extension of the physical entity of the welding gun to zero, and add the wire extension to the virtual model of the welding gun according to the welding process requirements;

[0079] Step 2-2: Ensure that the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are in a relatively parallel state; that is, adjust the physical entity of the welding robot so that the measurement value d1 of the first ultrasonic sensor is equal to the measurement value d2 of the second ultrasonic sensor;

[0080] Step 2-3: In the digital twin system, the virtual model of the welding robot can perform real-time synchronous mapping of the physical entity of the welding robot; therefore, when positioning the welding starting point, the physical entity of the welding gun is first controlled to move toward the vertical plane of the physical entity of the L-shaped welding workpiece. In the digital twin system, the virtual model of the welding gun moves toward the vertical plane of the virtual model of the L-shaped welding workpiece in real time and synchronously. Since the virtual model of the welding gun is set with a welding wire extension amount, the virtual model of the welding gun contacts the physical entity of the L-shaped welding workpiece faster than the physical entity of the welding gun. When the virtual model of the welding gun contacts the virtual model of the L-shaped welding workpiece, the collision function OnCollisionEnter (Collision other) is triggered, and the digital twin system sends an instruction to control the physical entity of the welding gun to stop moving forward and return a certain distance d3;

[0081] Specifically, the trigger condition of the collision function OnCollisionEnter (Collision other) is that the two colliding objects must have collision body properties at the same time and one of them must have rigid body properties. Therefore, in the digital twin system, a collision body component and a rigid body component are added to the welding gun virtual model, and a collision body component is added to the L-shaped welding workpiece.

[0082] Furthermore, the collision body component has a size attribute, so the size of the collision body needs to be adjusted to fit the outer surface of the welding gun virtual model and the L-shaped welding workpiece.

[0083] Step 2-4: Similarly, the physical entity of the welding gun is moved toward the horizontal plane of the physical entity of the L-shaped welding workpiece according to this method, and then returns to a distance d4 equal to d3;

[0084] Step 2-5: Finally, set the wire extension of the physical entity of the welding gun according to the requirements of the welding process to avoid squeezing of the welding wire when it contacts the welding workpiece.

[0085] Step 3: The physical entity of the welding gun starts the welding process, and the digital twin system is used to realize automatic tracking of the weld during the welding process. The digital twin system synchronously maps the motion state of the physical entity system in real time. When the weld is automatically tracked, the digital twin system controls the physical entity system to perform horizontal position compensation, limit and fault identification processing of the physical entity of the welding gun.

[0086] Step 3-1: For the digital twin system to control the physical entity system, perform horizontal position compensation for the physical entity of the welding gun. During the experiment, since the road surface is flat, the vertical changes of the physical entity of the welding gun can be ignored, but the physical entity of the welding robot may go astray, so the physical entity of the welding gun is set to position compensation in the horizontal direction; the details are as follows:

[0087] Step 3-1-1: First, after positioning at the welding starting point, the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are in a relatively parallel state; in the digital twin system, transform.position is used to obtain the coordinate value x1 of the X-axis of the welding gun virtual model in the parallel state; the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor are uploaded to the digital twin system;

[0088] Step 3-1-2: Update the relative position of the physical entity of the welding gun and the physical entity of the L-shaped welding workpiece in real time in the digital twin system; use the measurement value d′1 of the first ultrasonic sensor and the measurement value d′2 of the second ultrasonic sensor to determine whether the physical entity of the welding robot is in a relatively parallel state with the physical entity of the L-shaped welding workpiece. If d′1 is equal to d′2, they are in a relatively parallel state. If d′1 is not equal to d′2, calculate the deflection angle θ of the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece, and deflect the virtual model of the welding robot by θ through the program written in the digital twin system. The calculation process is shown in the following formula:

[0089]

[0090] Wherein, D is the installation interval distance between the first ultrasonic sensor and the second ultrasonic sensor; d1 and d2 are the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor.

[0091] Step 3-1-3: Use transform.position to obtain the coordinate value x2 of the X-axis of the welding gun virtual model, calculate the difference between x1 and x2, and convert it into the corresponding number of stepper motor pulses, which is transmitted to the electronic control system through the data acquisition and transmission system, so that the physical entity of the welding gun horizontal adjustment mechanism drives the physical entity of the welding gun to perform position compensation;

[0092] Furthermore, if we consider the digital twin system controlling the physical entity system to perform vertical position compensation of the physical entity of the welding gun; similarly, the digital twin system uses transform.position to obtain the Y-axis coordinate values ​​y1 and y2 of the virtual model of the welding gun, calculates the difference between y1 and y2, and converts it into the corresponding number of stepper motor pulses, which is transmitted to the electronic control system through the data acquisition and transmission system, so that the physical entity of the vertical adjustment mechanism of the welding gun drives the physical entity of the welding gun to perform position compensation.

[0093] Step 3-2: During the weld tracking process, the physical entity of the welding gun can also be controlled through the monitoring interface to adjust the accuracy of position compensation; the details are as follows:

[0094] Step 3-2-1: The motion monitoring interface is provided with an information bar showing the motion status of the physical entity of the welding robot. The relative position of the physical entity of the welding gun and the physical entity of the L-shaped welding workpiece can be observed through the information bar. For example, when the physical entity of the welding robot deviates from the physical entity of the L-shaped welding workpiece, the information bar will display "outward". If the information bar always displays "outward", it means that the compensation value of the physical entity of the welding gun is too small.

[0095] Step 3-2-2: Click the "Compensation Plus Button" in the motion monitoring interface to increase the number of pulses driving the stepper motor and increase the compensation value until the status information bar displays "No deviation". If the compensation value increases too much, the status information bar will display "Biased inside". Click the "Compensation Minus Button" in the motion monitoring interface to reduce the number of pulses driving the stepper motor and reduce the compensation value until the status information bar displays "No deviation".

[0096] Step 3-3: The digital twin system controls the physical entity system to perform fault identification and processing on the physical entity of the welding gun. The physical entity of the welding robot uses the digital twin technology to have the function of automatically stopping welding.

[0097] During the welding process, all components of the physical entity of the welding robot operate normally; in the digital twin system, all components of the virtual model of the welding robot also operate synchronously; when the physical entity of the welding robot fails and stops running, no relevant data will be generated. In the digital twin system, the virtual model of the welding robot will not run because it has no data drive, so its coordinate value will not change. Therefore, transform.position can be used to obtain the coordinate value of each virtual component. If the coordinate value of the virtual component does not change, it means that the physical component has failed; the written program sends instructions to the electronic control system to control the welding gun entity to stop welding. The details are as follows:

[0098] By setting a bool value, we can determine whether the physical entity of the welding robot is in motion. When the welding robot receives the relevant instructions to start running, the bool value is equal to true, indicating that the physical entity of the welding robot is in motion; when the welding robot receives the relevant instructions to stop running, the bool value is equal to false, indicating that the physical entity of the welding robot is in a stationary state. Only when the bool value is equal to true, the digital twin system will use transform.position to determine whether the coordinate value of the virtual model of the welding robot has changed, to prevent the welding robot from being misjudged as a fault by the digital twin system when the physical entity is in a stationary state and cannot weld normally.

[0099] Step 3-4: The digital twin system controls the physical entity system to limit the physical entity of the welding gun, as follows:

[0100] Implementation of the limit function: The virtual model of the welding robot can perform real-time synchronous mapping of the physical entity of the welding robot, and on this basis, the limit function is realized; during the welding process, the digital twin system uses transform.position to obtain the coordinates of the moving body in the virtual model of the welding gun horizontal adjustment mechanism and the virtual model of the welding gun vertical adjustment mechanism, and calculates the distance value between it and the two ends of the set moving trajectory. If the distance value is less than or equal to the set limit distance, the digital twin system will send a command to the electronic control system to stop the moving body in the physical entity of the welding gun horizontal adjustment mechanism and the physical entity of the welding gun vertical adjustment mechanism, thereby realizing the limit function;

[0101] Specifically, in this embodiment, taking the limiting of the physical entity of the welding gun horizontal adjustment mechanism as an example, the physical entity of the welding gun horizontal adjustment mechanism is a common ball screw slider combination, including a stepper motor, a slide rail, a slider, a ball screw and other components; since the virtual model of the welding robot can perform real-time synchronous mapping of the physical entity of the welding robot, therefore, during the welding process, the digital twin system uses transform.position to obtain the coordinates of the slider in the virtual model of the welding gun horizontal adjustment mechanism, and calculates the distance value between it and the two ends of the slide rail. If the distance value is less than or equal to the set limit distance, the digital twin system will send an instruction to the electronic control system to stop the stepper motor from rotating, thereby realizing the limiting function.

[0102] Step 4: The physical entity of the welding gun ends the welding process, and the digital twin system controls the physical entity system to reset the physical entity of the welding gun. The details are as follows:

[0103] Implementation of the reset function: Use transform.position to obtain the coordinates of the moving body in the virtual model of the welding gun horizontal adjustment mechanism and the welding gun vertical adjustment mechanism, and calculate the difference between the coordinates of the moving body and the initial position of the moving body. Write a program in the digital twin system to convert the difference into a control instruction, and then send it to the electronic control system through the data acquisition and transmission system, so that the moving body in the physical entity of the welding gun horizontal adjustment mechanism and the physical entity of the welding gun vertical adjustment mechanism moves again, and the moving body moves to the starting position to realize the reset function;

[0104] Specifically, in this embodiment, taking the resetting of the physical entity of the welding gun horizontal adjustment mechanism as an example, transform.position is also used to obtain the coordinates of the slider in the virtual model of the welding gun horizontal adjustment mechanism, and the difference between the coordinates of the slider and the initial position is calculated. A program is written in the digital twin system to convert the difference into the number of pulses corresponding to the stepper motor using a series of formulas, and then sent to the electronic control system through the data acquisition and transmission system, so that the stepper motor rotates and drives the slider to move to the starting position to realize the reset function. The physical entity of the welding gun ends the welding process.

[0105] The above description is only used to help understand the method of the present invention and its core essence, but the protection scope of the present invention is not limited thereto. For those skilled in the art in the art, equivalent replacement or change according to the technical solution and inventive concept of the present invention within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A welding method of a mobile welding robot based on digital twin, characterized in that: A mobile welding robot welding system is used, wherein the mobile welding robot welding system includes: a physical entity system, an electric control system, a data transmission system, and a digital twin system; A physical entity system, including a welding robot physical entity and an L-shaped welding workpiece physical entity; The digital twin system includes a welding robot virtual model, an L-shaped welding workpiece virtual model, a motion monitoring interface, a coordinate acquisition module, and a collision trigger module; the collision trigger module uses a collision function to trigger the contact between the welding robot virtual model and the L-shaped welding workpiece virtual model, so as to control the physical entity of the welding robot to locate the welding starting point; The electronic control system is used to collect the motion state data of the physical entity of the welding robot and feed it back to the data transmission system, and receive instructions to control the power supply and motion state of the physical entity of the welding robot; A data transmission system, used to upload the motion state data collected by the electronic control system to the digital twin system, and to send the instructions of the digital twin system to the electronic control system; The method comprises the following steps: S1, real-time synchronous mapping of the physical entity system to the digital twin system; S2. The digital twin system controls the physical entity system to locate the welding starting point. The digital twin system sets the welding starting point of the physical entity of the welding gun based on the process target wire extension amount of the physical entity of the welding gun. The digital twin system controls the physical entity system to locate the welding starting point as follows: S2-1. The wire extension amount of the physical entity of the welding gun is set to zero, and the wire extension amount of the virtual model of the welding gun is set to the process target wire extension amount; and the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are controlled to be in a relatively parallel state, and the digital twin system synchronously maps the motion state of the physical entity system in real time; S2-2, in the physical entity system, the physical entity of the welding gun is controlled to move toward the vertical surface of the physical entity of the L-shaped welding workpiece, and in the digital twin system, the virtual model of the welding gun is synchronously moved toward the vertical surface of the virtual model of the L-shaped welding workpiece in real time; if the virtual model of the welding gun contacts the vertical surface of the virtual model of the L-shaped welding workpiece, the digital twin system triggers the collision function, and the digital twin system sends a command to control the physical entity of the welding gun to stop moving forward and return a certain distance d3; S2-3, similarly, the physical entity of the welding gun moves toward the horizontal plane of the physical entity of the L-shaped welding workpiece. If the virtual model of the welding gun contacts the horizontal plane of the virtual model of the L-shaped welding workpiece, the digital twin system triggers the collision function, and the digital twin system sends a command to control the physical entity of the welding gun to stop moving forward and then return to a distance d4 equal to d3; S2-4, setting the welding wire extension amount of the physical entity of the welding gun to the process target welding wire extension amount; S3. The physical entity of the welding gun starts the welding process based on the positioning of the welding starting point. The digital twin system automatically tracks the weld during the welding process, and updates the relative position and motion state of the virtual model of the welding gun and the virtual model of the L-shaped welding workpiece in real time. When the weld is automatically tracked, the digital twin system controls the physical entity system to perform horizontal position compensation, limit and fault identification processing on the physical entity of the welding gun; S4. The physical entity of the welding gun ends the welding process, and the digital twin system controls the physical entity system to reset the physical entity of the welding gun.

2. The welding method of a mobile welding robot based on digital twin according to claim 1 is characterized in that: In S1, the physical entity system is synchronously mapped to the digital twin system in real time, as follows: S1-1. Establish a welding robot virtual model and an L-shaped welding workpiece virtual model in Unity according to the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece; S1-2, controlling the relative position of the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece and the relative position of the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece to be consistent; S1-3, control the welding robot virtual model and the welding robot physical entity to maintain the same motion state.

3. The welding method of a mobile welding robot based on digital twin according to claim 1 is characterized in that: The digital twin system in S3 controls the physical entity system to compensate the position of the welding gun physical entity in the horizontal direction, as follows: A-1. After positioning the welding starting point, the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece are in a relatively parallel state; in the digital twin system, transform.position is used to obtain the coordinate value x1 of the X-axis of the welding gun virtual model in the parallel state, and the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor are uploaded to the digital twin system; A-2. Determine whether the physical entity of the welding robot is in a relatively parallel state with the physical entity of the L-shaped welding workpiece by using the measurement values ​​of the first ultrasonic sensor and the second ultrasonic sensor; if the measurement value of the first ultrasonic sensor is not equal to the measurement value of the second ultrasonic sensor, calculate the deflection angle between the physical entity of the welding robot and the physical entity of the L-shaped welding workpiece, and deflect the virtual model of the welding robot by the deflection angle in the digital twin system; A-3. The digital twin system uses transform.position to obtain the coordinate value x2 of the X-axis of the virtual model of the welding gun, calculates the difference between x1 and x2, and converts it into corresponding control instructions. The digital twin system sends instructions to the electronic control system, so that the physical entity of the welding gun horizontal adjustment mechanism drives the physical entity of the welding gun to perform position compensation.

4. The welding method of a mobile welding robot based on digital twin according to claim 3 is characterized in that: When the digital twin system in S3 automatically tracks the weld during welding, it can control the physical entity of the welding gun to adjust the precision of position compensation in the horizontal direction through the motion monitoring interface; the details are as follows: The relative position of the physical entity of the welding gun and the physical entity of the L-shaped welding workpiece is observed through the information bar, and whether the physical entity of the welding robot deviates from the physical entity of the L-shaped welding workpiece is observed; the control instructions are input through the control buttons in the motion monitoring interface, and the digital twin system sends instructions to the electronic control system to adjust the physical entity of the welding gun horizontal adjustment mechanism to drive the physical entity of the welding gun to move. Compensation speed.

5. The welding method of a mobile welding robot based on digital twin according to claim 1 is characterized in that: The digital twin system in S3 controls the physical entity system to limit the physical entity of the welding gun, as follows: B-1. Use transform.position in the digital twin system to obtain the coordinates of the moving bodies in the virtual models of the welding gun horizontal adjustment mechanism and the welding gun vertical adjustment mechanism; B-2. Calculate the distance between the coordinates of the moving body and the two ends of the set moving trajectory. If the distance value is less than or equal to the set limit distance, the digital twin system sends a command to the electronic control system to stop the moving body in the physical entity of the welding gun horizontal adjustment mechanism and the physical entity of the welding gun vertical adjustment mechanism, thereby achieving the limit of the physical entity of the welding gun.

6. The welding method of a mobile welding robot based on digital twin according to claim 1 is characterized in that: The digital twin system in S3 controls the physical entity system to perform fault identification processing on the physical entity of the welding gun, as follows: C-1. In the digital twin system, a bool value is set to determine whether the physical entity of the welding robot is in motion. If the bool value is true, it means that the physical entity of the welding robot is in motion. If the bool value is false, it means that the physical entity of the welding robot is stationary. C-2. When the bool value is equal to true, the digital twin system uses transform.position to obtain the coordinate value of the virtual model of the welding robot. If the coordinate value of the virtual model of the welding robot does not change, the physical entity of the welding robot fails; the digital twin system sends instructions to the electronic control system to control the physical entity of the welding gun to stop welding.

7. A mobile welding robot welding system based on digital twinning applied in any of the methods described in claims 1-6, comprising: Physical entity system, electronic control system, data transmission system, digital twin system; characterized by: A physical entity system, including a welding robot physical entity and an L-shaped welding workpiece physical entity; Digital twin system, including welding robot virtual model, L-shaped welding workpiece virtual model, motion monitoring interface, coordinate acquisition module, and collision trigger module; The motion monitoring interface is provided with an information bar for displaying the motion state of the physical entity of the welding robot and a control button for controlling the motion state of the physical entity of the welding robot; The coordinate acquisition module uses transform.position to obtain the coordinate values ​​of the welding robot virtual model and the L-shaped welding workpiece virtual model, which is used to control the limit, reset, horizontal position compensation and fault identification of the physical entity of the welding robot during the welding process; The collision trigger module uses a collision function to trigger the contact between the virtual model of the welding robot and the virtual model of the L-shaped welding workpiece, so as to control the physical entity of the welding robot to locate the welding starting point; The electronic control system is used to collect the motion state data of the physical entity of the welding robot and feed it back to the data transmission system, and receive instructions to control the power supply and motion state of the physical entity of the welding robot; The data transmission system is used to upload the motion state data collected by the electronic control system to the digital twin system, and to send the instructions of the digital twin system to the electronic control system.

8. The mobile welding robot welding system based on digital twin according to claim 7 is characterized in that: The welding robot physical entity includes a mobile chassis physical entity, a welding gun vertical adjustment mechanism physical entity, a welding gun horizontal adjustment mechanism physical entity, a welding gun swing mechanism physical entity, and a welding gun physical entity; a first ultrasonic sensor and a second ultrasonic sensor are installed on one side of the mobile chassis physical entity close to the L-shaped welding workpiece physical entity; The welding robot virtual model includes a mobile chassis virtual model, a welding gun vertical adjustment mechanism virtual model, a welding gun horizontal adjustment mechanism virtual model, a welding gun swing mechanism virtual model, and a welding gun virtual model.

9. The mobile welding robot welding system based on digital twin according to claim 8, characterized in that: The welding gun virtual model is equipped with a collision body component and a rigid body component, and the L-shaped welding workpiece virtual model is equipped with a collision body component; when the welding gun virtual model and the L-shaped welding workpiece virtual model come into contact, a collision function can be triggered to locate the welding starting point of the welding gun physical entity.

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