Robot GTAW wire filling speed self-adaptive control method based on visual sensing

Abstract

The invention relates to a robot GTAW wire filling speed self-adaptive control method based on visual sensing. A visual sensor is used for collecting real-time images in the welding process; detecting the position of the tail end of the welding wire in the arc in real time by using a distance calculation method of the tail end of the welding wire and the arc center; measuring the wire filling speed by using an isochronous marking method; and the wire filling speed is self-adapted by using the wire filling speed self-adaptive control method. According to the method, in the GTAW process of the robot, accurate recognition of the wire filling speed state is successfully achieved, and the intelligent self-adjusting function of the self-adaptive wire filling speed is further achieved.

Description

Technical Field

[0001] The invention relates to the field of robot GTAW wire filling speed adaptive control, and is a robot GTAW wire filling speed adaptive control method based on visual sensing. Background Art

[0002] In recent years, with the rapid development of arc additive technology, higher and higher requirements have been put forward for the automation and intelligence of robot GTAW (gas shielded welding), and GTAW is widely used in aerospace, marine equipment, nuclear power construction and other fields. The upgrading of GTAW technology is imminent. In the GTAW process, the wire filling speed has a crucial influence on the welding efficiency and weld quality. The appropriate wire filling speed is conducive to maintaining the stability of the arc and forming a beautiful weld. However, there are currently few methods for realizing the adaptive control of the wire filling speed of robot GTAW and they are not accurate enough. To address this problem, the present invention discloses a method for adaptive control of the wire filling speed of robot GTAW based on visual sensing. Summary of the invention

[0003] The method for adaptive control of robot GTAW wire filling speed based on visual sensing is based on the real-time image captured by the visual sensor, which is processed to obtain the distance deviation between the end of the welding wire and the center of the arc, and then the wire feeding speed is adjusted so that the end of the welding wire can always be kept in the most suitable welding range of the arc center; the visual sensor captures the real-time image by fixing the industrial camera with a clamping device on a surface at 90° to the fixed position of the wire feeding tube to collect image information, and the collected image information is transmitted to the image information processor in real time by wireless signals, and the image information processor processes the image information to obtain the coordinate information of the end of the welding wire. When the end of the welding wire can be kept in the range D, the welding speed is stable and no longer changes, so as to achieve adaptive control of the welding speed.

[0004] The system schematic diagram of the robot GTAW wire filling speed adaptive control method based on visual sensing is as follows: Figure 1As shown, it is characterized in that: the robot GTAW wire filling speed adaptive control method based on visual sensing is realized by using the robot GTAW wire filling speed adaptive control system based on visual sensing; the robot GTAW wire filling speed adaptive control system based on visual sensing is composed of a visual sensor, an image information processor, a robot GTAW wire filling speed adaptive controller, a high-precision wire feeder, a wire filling speed sensor, a wire feeding tube, a welding gun, and a clamping device; the visual sensor is used to monitor the end position of the welding wire, and the visual sensor is used to collect real-time images of the welding process and transmit the image information to the image information processor; the image information processor processes the received image information to obtain the distance between the end of the welding wire and the center of the arc, and transmits the distance data between the end of the welding wire and the center of the arc to the robot GTAW adaptive speed controller in real time through the communication bus; the robot GTAW wire filling speed adaptive controller is used to identify the current wire filling speed state and control the adaptive wire filling speed of the high-precision wire feeder through the control bus; the high-precision wire feeder is used to accurately control the wire feeding speed; the wire filling speed sensor is used to detect the wire filling speed in real time; the clamping device is used to fix the visual sensor and the wire feeding tube on the welding gun.

[0005] The method for adaptively controlling the wire filling speed of a robot GTAW based on visual sensing is characterized in that: a distance calculation method between the end of the welding wire and the center of the arc is used to detect the position of the end of the welding wire in the arc in real time; the distance calculation method between the end of the welding wire and the center of the arc is realized by collecting and analyzing the real-time image information captured by the visual sensor through an image information processor, and then calculating the accurate distance data using an image processing algorithm; the image processing algorithm is that the image information processor grayscales the received real-time welding process image, defines the arc and welding wire area image, and uses a Gaussian filtering method to calculate the distance between the end of the welding wire and the center of the arc. The image of this area is filtered, and then the wire edge detection algorithm is used to obtain the coordinates of the wire end; the visual sensor is fixed to the front end of the welding gun, and the plane formed by its center axis and the welding gun center axis is perpendicular to the plane formed by the welding gun center axis and the wire feed tube center axis, and the center line of the image captured by the sensor coincides with the arc center line, and a rectangular coordinate system is established with the midpoint of the image center line as the origin and the direction of the wire feed tube as the positive axis. The horizontal coordinate of the wire end is the distance between the arc center and the wire end, denoted as d; after obtaining the distance d between the wire end and the arc center, the data is transmitted to the robot GTAW wire filling speed adaptive controller through the communication bus. The flow of the method for calculating the distance between the wire end and the arc center is as follows: Figure 4 shown.

[0006] The robot GTAW wire filling speed adaptive control method based on visual sensing is characterized by: using a high-precision wire feeder and a wire filling speed sensor to accurately control the wire filling speed; the high-precision wire feeder is a device for accurately controlling the wire feeding speed; the wire filling speed sensor is a device for accurately detecting the wire filling speed; the wire filling speed sensor receives the welding wire sent by the high-precision wire feeder and measures the speed using an isochronous marking method; the isochronous marking method is implemented by a speed measuring device of the wire filling speed sensor; the schematic diagram of the wire filling speed sensor is as follows: Figure 2 As shown on the left, the speed measuring device of the wire filling speed sensor consists of two parts, the first part is the isochronous marking device, and the second part is the marking detection device; the isochronous marking device consists of an ink outlet, an ink cartridge, and a blower. Figure 2 On the right is the internal principle diagram of the isochronous marking device. The blower blows the toner in the ink cartridge out of the ink outlet and hits the welding wire to make a mark. The time interval of the mark is denoted as t; the mark detection device uses a visual sensor to detect the distance between two marks, and the distance between the two marks is denoted as x; the wire filling speed is obtained after the welding wire passes through the wire filling speed sensor, denoted as v; the wire filling speed v=x / t.

[0007] The robot GTAW wire filling speed adaptive control method based on visual sensing, the robot GTAW wire filling speed adaptive control method based on visual sensing is as follows Figure 5 As shown, it is characterized in that: the said wire filling speed adaptive control method is realized by monitoring the distance change between the end of the welding wire and the center of the arc; when the distance d between the end of the welding wire and the center of the arc is greater than D / 2 and the welding wire does not enter the range D, as Figure 3 As shown on the left, the horizontal axis is positive, and the robot GTAW wire filling speed adaptive controller sends a signal to the high-precision wire feeder to increase the wire feeding speed v; when the distance d between the end of the welding wire and the arc center is greater than D / 2 and the welding wire has entered the range D, as shown in Figure 3 As shown on the right, the horizontal axis is negative, and the robot GTAW wire feeding speed adaptive controller sends a signal to the high-precision wire feeder to reduce the wire feeding speed v; the range D is the optimal welding range measured experimentally. When the end of the welding wire is stable in the range D, the welding speed remains stable.

[0008] Advantageous Effects of the Invention

[0009] The present invention relates to a robot GTAW wire filling speed adaptive control method based on visual sensing. A visual sensor is used to collect real-time images of the welding process; a distance calculation method between the end of the welding wire and the center of the arc is used to detect the position of the end of the welding wire in the arc in real time; an isochronous marking method is used to measure the wire filling speed; and a wire filling speed adaptive control method is used to adaptively adjust the wire filling speed. The present invention successfully realizes the accurate recognition of the wire filling speed state in the robot GTAW process, and further realizes the intelligent self-regulation function of the adaptive wire filling speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the schematic diagram of the robot GTAW wire filling speed adaptive control system based on visual sensing.

[0011] Figure 2 On the left is the schematic diagram of the wire filling speed sensor, and on the right is the internal schematic diagram of the isochronous marking device.

[0012] Figure 3 The left image is a welding process image when the welding wire has not entered the range D, and the right image is a welding process image when the welding wire has entered the range D.

[0013] Figure 4 The flowchart of the method for calculating the distance between the end of the welding wire and the center of the arc is shown in FIG.

[0014] Figure 5 This is a flow chart of the adaptive control method for robot GTAW wire filling speed based on visual sensing. DETAILED DESCRIPTION

[0015] In order to better express the technical solution and beneficial effects of the entire invention, the present invention is further described in detail below with reference to the accompanying drawings and implementation examples. The implementation methods of the present invention are not limited thereto.

[0016] Step 1: Calculate the distance between the end of the welding wire and the center of the arc

[0017] In the robot GTAW process, the best welding effect can be obtained when the end of the welding wire is located at the center of the arc. Through experiments and data analysis, the range of the best arc center area D can be measured. How to always keep the end of the welding wire within the range of D is a difficult problem. To solve this problem, the present invention discloses a method for calculating the distance between the end of the welding wire and the arc center. Figure 1 As shown, when the arc is successfully struck and welding begins, the visual sensor on the clamping device starts to operate, capturing the image information of the welding process in real time and transmitting it to the image information processor to calculate the distance between the end of the welding wire and the center of the arc. After receiving the image information, the image information processor uses the image processing algorithm to process the picture and then obtains the distance d from the end of the welding wire to the center of the arc and the positive and negative horizontal coordinates of the end of the welding wire, and transmits the data to the robot GTAW wire filling speed adaptive controller through the communication bus.

[0018] Step 2: Robotic GTAW wire filling speed adaptive control

[0019] In the robot GTAW process, the size of the wire filling speed has a very serious impact on the welding efficiency and the quality of the weld. Therefore, it is necessary to control the wire filling speed during welding to obtain the optimal wire filling speed. In view of this problem, the present invention discloses a robot GTAW wire filling speed adaptive control method. The robot GTAW wire filling speed adaptive controller receives the distance d from the end of the welding wire to the center of the arc and makes a judgment. If ≤D / 2, the wire filling speed remains unchanged. If d≥D / 2, the next judgment is made. When the welding wire intersects with the range D, the robot GTAW wire filling speed adaptive controller sends a signal to the high-precision wire feeder to lower the wire feeding speed v; when the welding wire does not intersect with the range D, the robot GTAW wire filling speed adaptive controller sends a signal to the high-precision wire feeder to increase the wire feeding speed v. At the same time, the wire feeding speed measured by the wire filling speed sensor is fed back to the robot GTAW wire filling speed adaptive controller. When the end of the welding wire is stable in the range D, the speed no longer changes, thereby achieving the purpose of adaptive control of the wire filling speed.

Claims

1. A robot GTAW wire filling speed adaptive control method based on visual sensing is used for robot GTAW to achieve adaptive control of wire filling speed, so that the end of the welding wire can always be kept in the center area of ​​the arc, improving welding efficiency and quality. The method is characterized by: The robot GTAW wire filling speed adaptive control method based on visual sensing is realized by using the robot GTAW wire filling speed adaptive control system based on visual sensing; the robot GTAW wire filling speed adaptive control system based on visual sensing is composed of a visual sensor, an image information processor, a robot GTAW wire filling speed adaptive controller, a high-precision wire feeder, a wire filling speed sensor, a wire feeding tube, a welding gun, and a clamping device; the visual sensor is used to monitor the end position of the welding wire, and the visual sensor is used to collect real-time images of the welding process, and the image information is transmitted to the image information processor; the image information processor processes the received image information to obtain the distance between the end of the welding wire and the center of the arc, and transmits the distance data between the end of the welding wire and the center of the arc to the robot GTAW adaptive speed controller in real time through a communication bus; the robot GTAW wire filling speed adaptive controller is used to identify the current wire filling speed state and control the adaptive wire filling speed of the high-precision wire feeder through a control bus; the high-precision wire feeder is used to accurately control the wire feeding speed; the wire filling speed sensor is used to detect the wire filling speed in real time; the clamping device is used to fix the visual sensor and the wire feeding tube on the welding gun.

2. The method for adaptively controlling the wire filling speed of robot GTAW based on visual sensing according to claim 1 is characterized in that: The position of the end of the welding wire in the arc is detected in real time by using a distance calculation method between the end of the welding wire and the center of the arc; the distance calculation method between the end of the welding wire and the center of the arc is realized by collecting and analyzing the real-time image information captured by the visual sensor through an image information processor, and then calculating the accurate distance data using an image processing algorithm; the image processing algorithm is that the image information processor grays the received real-time welding process image, defines the arc and welding wire area image, uses a Gaussian filtering method to filter the area image, and then uses a welding wire edge detection algorithm to obtain the coordinates of the end of the welding wire; the visual sensor is fixed to the front end of the welding gun, and the plane formed by its central axis and the central axis of the welding gun is perpendicular to the plane formed by the central axis of the welding gun and the central axis of the wire feed tube, and the center line of the image captured by the sensor coincides with the center line of the arc, and a rectangular coordinate system is established with the midpoint of the image center line as the origin and the direction of the wire feed tube as the positive axis, and the horizontal coordinate of the end of the welding wire is the distance between the arc center and the end of the welding wire, which is recorded as d; after obtaining the distance d between the end of the welding wire and the arc center, the data is transmitted to the robot GTAW wire filling speed adaptive controller through a communication bus.

3. The method for adaptively controlling the wire-filling speed of robot GTAW based on visual sensing according to claim 1 is characterized in that: The wire-filling speed is precisely controlled by using a high-precision wire feeder and a wire-filling speed sensor; the high-precision wire feeder is a device for precisely controlling the wire-filling speed; the wire-filling speed sensor is a device for precisely detecting the wire-filling speed; the wire-filling speed sensor receives the welding wire sent by the high-precision wire feeder and measures the speed by using an isochronous marking method; the isochronous marking method is implemented by a speed measuring device of the wire-filling speed sensor; the speed measuring device of the wire-filling speed sensor consists of two parts, the first part is an isochronous marking device, and the second part is a marking detection device; The isochronous marking device is composed of an ink outlet, an ink cartridge, and a blower. The blower blows the toner in the ink cartridge out of the ink outlet and hits the welding wire to make a mark. The time interval of the mark is denoted as t; the mark detection device uses a visual sensor to detect the distance between two marks, and the distance between the two marks is denoted as x; the wire filling speed is obtained after the welding wire passes through the wire filling speed sensor, denoted as v; the wire filling speed v=x / t.

4. The method for adaptively controlling the wire filling speed of robot GTAW based on visual sensing according to claim 1 is characterized in that: The wire filling speed adaptive control method is achieved by monitoring the change in the distance between the end of the welding wire and the center of the arc; when the distance d between the end of the welding wire and the center of the arc is greater than D / 2 and the welding wire has not entered the range D, the robot GTAW wire filling speed adaptive controller sends a signal to the high-precision wire feeder to increase the wire feeding speed v; when the distance d between the end of the welding wire and the center of the arc is greater than D / 2 and the welding wire has entered the range D, the robot GTAW wire filling speed adaptive controller sends a signal to the high-precision wire feeder to reduce the wire feeding speed v; the range D is the optimal welding range measured experimentally.

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