A real-time trajectory planning method for a right-angle weld under a biased installation state of a welding gun

Abstract

The application provides a real-time trajectory planning method for a right-angle weld in a welding gun offset mounting state, comprising: 1) welding robot board card initialization; 2) a host computer acquires default trajectory planning data or modified trajectory planning data; 3) the welding robot starts tracking, the host computer acquires data of an angle sensor and a laser ranging sensor in a tracking process, and the host computer performs online trajectory planning on the welding robot according to the real-time acquired data; and 4) whether right-angle weld joint welding is finished is detected. The method takes a right-angle weld joint trajectory planning theory as a breakthrough point, real-time trajectory planning is performed on the right-angle weld joint with the aid of a sensor, the absolute angle of the robot is measured in real time every sampling period, the real-time speed of the robot vehicle body can be calculated based on the change of the angle, the right-angle weld joint is tracked, and the accuracy of the trajectory planning is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robot trajectory planning technology, in particular to a real-time trajectory planning method for a right-angle weld in a welding gun offset installation state. BACKGROUND

[0002] The most widely used industrial robot is a welding robot. With the increasing demand for welding quality and efficiency and the increasing cost of manual welding, the demand for welding robots is very high in various industries. In some complex working conditions, such as large-scale engineering structures, large-scale containers, ships, offshore platforms, and large-diameter pipelines, the working environment is very harsh, and there are a large number of complex welds that cannot be achieved by robot welding. Manual welding is still used in these fields, and the welding robot rarely appears in these fields. Therefore, it is necessary to study the robot.

[0003] The study of robots mainly focuses on the planning of robots. The planning of robots is the solution process of the solution of the required solution of the robot to complete the task, and the trajectory planning of the robot refers to the process of calculating the expected motion trajectory according to the requirements of the task. In robot control, the trajectory planning of the robot plays an important role, which directly affects the accuracy and speed of control. In the welding task, the identification and tracking of the weld are the most important tasks of trajectory planning. When facing a right-angle weld, the right-angle weld trajectory planning theory is usually used as the starting point, and the right-angle weld trajectory planning theory is often used for research in the case where the welding gun is located on the extension line of the connection line between the rotation center and the driving wheel center. Therefore, an effective method is needed to realize the trajectory planning method in the case where the welding gun lags behind the extension line of the connection line between the rotation center and the driving wheel center. SUMMARY

[0004] The present application aims to solve the above technical problems by providing a real-time trajectory planning method for a right-angle weld in a welding gun offset installation state. This method can improve the accuracy of trajectory planning and expand the applicability of the cross slide installation position.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0006] A real-time trajectory planning method for a right-angle weld in a welding gun offset installation state, comprising the following steps:

[0007] Step S1. Initialize the welding robot board card.

[0008] Step S2. Obtain default trajectory planning data or modify trajectory planning data.

[0009] Step S3. The welding robot starts tracking, and the host computer collects data of the angle sensor and the laser ranging sensor at regular intervals during the tracking process. The host computer performs online trajectory planning for the welding robot according to the real-time collected data.

[0010] Step S4. It is detected whether the straight weld is completed.

[0011] Further, the trajectory planning data is modified in step S2, and the specific process is as follows:

[0012] Step S21. The size of the lag angle θ1 is determined.

[0013] The distance d between the rotation center and the welding torch is measured OA The distance d between the point A where the welding torch is located on the weld seam for the first time and the point B where the welding torch is located on the weld seam again is measured AB Then, θ1, d OA and d AB satisfy the formula:

[0014]

[0015] Step S22. According to the obtained lag angle θ1, a relationship between the slide block and the welding robot vehicle speed and the welding speed is established, and the relationship between the welding robot vehicle speed V R in the radial direction, the welding robot vehicle rotation speed V c and the welding robot welding speed V 焊接 is as follows:

[0016]

[0017]

[0018] Step S23. According to the relationship given in step S22 and the lag angle θ1 obtained in step S21, the trajectory planning data of the welding robot is modified according to the actual welding requirements.

[0019] Further, the host computer performs online trajectory planning for the welding robot according to the real-time collected data in step S3, and the trajectory planning for the welding robot vehicle rotation angle from 0° to 45° is as follows:

[0020] When the angle is from 0° to , the slide block is in the back shrink state. First, the speed of the welding robot vehicle and the slide block from 0° to is planned.

[0021] Let θ be the angle through which the welding robot vehicle rotates in the sampling period of the host computer, and the relationship is:

[0022]

[0023]

[0024] Since the angular velocity of the welding robot's rotating drive wheel is equal to the angular velocity at the welding torch, the following relationship exists:

[0025]

[0026]

[0027] In the above formula, b is the distance from the center of the right drive wheel to the center of rotation, and R is the distance from the welding torch to the center of rotation;

[0028] By combining equations (4) and (7), the linear velocity of the right drive wheel can be obtained.

[0029]

[0030] Since the movement of the welding torch in the direction perpendicular to the weld seam can only be achieved by the movement of the lateral slider, the velocity V of the welding torch in the radial direction is... R The speed V of the slider due to the contraction or extension of the welding torch h Different, slider speed V h With the radial velocity V R There is a relation:

[0031]

[0032] The slider velocity can be obtained by combining equations (5) and (9).

[0033]

[0034] Similarly, By planning within a 45° range, the slider speed Vh and the right drive wheel speed V can be obtained. 右轮 :

[0035]

[0036] Based on the calculated speeds of the drive wheels and the vehicle body, the robot body and slider are coordinated for control, and the trajectory planning for the first 45° of the right-angle weld is completed.

[0037] Furthermore, in step S3, the host computer performs online trajectory planning for the welding robot based on the real-time collected data. The trajectory planning for the welding torch when it is located on the rotation center line is as follows:

[0038] During the 45° rotation of the vehicle body, the welding torch moves a distance L. y Equal to the distance L between the welding torch at the initial position and the center of rotation x When the welding torch lags behind the center of rotation, the distance L that the welding torch moves is caused by the angle θ2 that the welding torch lags behind the center of rotation.y Not equal to L x At this time, θ2, L x , L y Satisfy the relationship:

[0039]

[0040] In the above formula, L y is the longitudinal distance of the welding gun relative to the rotation center, L x is the horizontal distance of the welding gun relative to the rotation center, and θ2 is the lag angle of the welding gun relative to the rotation center line.

[0041] By combining equation (11), L x satisfies the relationship:

[0042] Lx=d OA *cosθ2 (12)

[0043] Therefore, when the welding robot vehicle body rotation angle is between 45° and 90°, the distance R of the welding gun from the rotation center satisfies the relationship:

[0044]

[0045] By combining equations (3)-(10), the angular velocity ω of the welding robot vehicle body, the right drive wheel speed V 右 , and the speed V h of the sliding block can be obtained as follows:

[0046]

[0047]

[0048]

[0049] According to the calculated drive wheel speed and vehicle body speed, the robot vehicle body and the sliding block are cooperatively controlled to complete the 45° trajectory planning after the right-angle weld.

[0050] Compared with the prior art, the beneficial effects of the present application are:

[0051] (1) The present application adopts real-time acquisition of sensor data, and real-time trajectory planning for the sliding block and the robot vehicle body. In the face of right-angle welds, accurate tracking can be performed.

[0052] (2) The present application takes the right-angle weld trajectory planning theory as the starting point. The right-angle weld trajectory planning theory is commonly used in the study of the case where the welding gun is located on the extension line of the connection line between the rotation center and the drive wheel center. By borrowing this theory, the welding gun lagging behind the rotation center and the extension line of the connection line between the drive wheel center are studied, and the sensor is used to perform real-time trajectory planning for the right-angle weld.

[0053] (3) The method provides a theoretical basis for the installation position of the sliding block, and can be used as a reference suggestion for mechanical design. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 A flowchart of a real-time trajectory planning method for a right-angle weld in a welding gun offset installation state of the application;

[0055] Figure 2 A schematic diagram of the extension line of the welding gun lag rotation center and the driving wheel center (left) and a partial enlarged view (right) in the embodiment of the application;

[0056] Figure 3 A welding gun lag rotation position diagram in the embodiment of the application;

[0057] Figure 4 A rotation process θ1 diagram in the embodiment of the application;

[0058] Figure 5 A speed relationship diagram of the welding robot vehicle body and the sliding block in the embodiment of the application;

[0059] Figure 6 A difference diagram between the sliding block speed V h and the radial direction speed V R ;

[0060] Figure 7 A trajectory planning diagram when the rotation angle is 45° to 90° in the lag state in the embodiment of the application;

[0061] Figure 8 An effect diagram of the robot welding trajectory planned according to the method of the application;

[0062] In the figure: 1, left and right driven wheels; 2, left and right chains; 3, left and right driving wheel centers; 4, welding gun position; 5, vehicle body rotation center; 6, weld; 0, rotation center. DETAILED DESCRIPTION

[0063] The technical solutions of the application will be further explained and described below in combination with the drawings.

[0064] Embodiment: Referring to Figures 1-8 .

[0065] As Figure 1 shown, a real-time trajectory planning method for a right-angle weld in a welding gun offset installation state, comprising the following steps:

[0066] Step S1. Welding robot board card initialization;

[0067] Step S2. Obtain default trajectory planning data or modify trajectory planning data;

[0068] Step S3. The welding robot starts tracking, and the host computer collects data of the angle sensor and the laser ranging sensor at regular time intervals during tracking. The host computer performs online trajectory planning for the welding robot according to the real-time collected data.

[0069] Step S4. Detect whether the straight weld is completed.

[0070] Specifically, the trajectory planning method in the embodiment is based on a traditional trajectory planning method, and the trajectory of the welding robot is planned according to the division of the lag angle θ1, 0° to 45° and 45° to 90°. Figure 2 and Figure 3 The specific planning process is as follows:

[0071] 1) Determine the size of the lag angle θ1;

[0072] Figure 4 FIG. 1 is a schematic diagram of the lag angle θ1. The distance d between the rotation center and the welding torch is measured OA and the distance d between the point A where the initial position of the welding torch is located on the weld and the point B where the welding torch is located on the weld again AB , then θ1, d OA and d AB satisfy the formula:

[0073]

[0074] 2) According to the obtained lag angle θ1, the relationship between the slide block and the welding robot vehicle speed and the welding speed is established, and the relationship between the welding robot vehicle speed V R , the rotation speed V c of the welding robot vehicle and the welding speed V 焊接 of the welding robot is as follows:

[0075]

[0076]

[0077] According to the lag angle θ1 obtained in step 1) and the relationship given in 2), the trajectory planning data of the welding robot is modified according to the actual welding requirements.

[0078] 3) The trajectory planning when the rotation angle of the welding robot vehicle is 0° to 45° is as follows:

[0079] When the angle is 0° to , the slide block is in a back retraction state, Figure 5To draw the speed relation diagram of the welding robot car body and the slider in this angle interval, first plan 0° to the angle of the welding robot car body and the slider:

[0080] Let the angle of the welding robot car body rotated in the sampling period of the upper computer be θ, then there is a relation:

[0081]

[0082]

[0083] Since the angular velocity of the welding robot car body rotating the driving wheel is equal to the angular velocity at the welding torch, there is a relation:

[0084]

[0085]

[0086] In the above formula, b is the distance from the center of the right driving wheel to the center of rotation, and R is the distance from the welding torch to the center of rotation;

[0087] Solving equations (4)-(7) can get the linear speed of the right driving wheel

[0088]

[0089] Since the movement of the welding torch in the vertical weld direction can only be realized by the movement of the transverse slider, the speed of the welding torch in the radial direction V R is different from the slider speed V h due to the contraction or extension of the slider, and their relationship is shown in Figure 6 The slider speed V h and the radial speed V R have a relation:

[0090]

[0091] Solving equations (5) and (9) can get the slider speed

[0092]

[0093] According to the calculated driving wheel speed and car body speed, the cooperative control of the robot car body and the slider is carried out to complete the trajectory planning of the first 45° of the right-angle weld.

[0094] 4) The trajectory planning when the welding robot car body rotation angle is between 45° and 90° is as follows:

[0095] As shown in Figure 7 , the planning diagram when the rotation angle is between 45° and 90°, during the 45° rotation of the car body, the welding torch moves a distance Ly equal to the distance L between the initial position of the welding torch and the rotation center x When the welding torch lags behind the rotation center, the welding torch moves a distance L due to the lag angle θ2 of the welding torch behind the rotation center y not equal to L x At this time, θ2 and L x , L y satisfy the following relationship:

[0096]

[0097] In the above formula, L y is the longitudinal distance of the welding torch relative to the rotation center, L x is the horizontal distance of the welding torch relative to the rotation center, and θ2 is the lag angle of the welding torch relative to the rotation center line. In this embodiment, θ2 is obtained through experiments

[0098] By combining equation (11), L x satisfies the following relationship:

[0099] Lx = d OA *cosθ2 (12)

[0100] When the rotation angle of the welding robot vehicle body is between 45° and 90°, the distance R of the welding torch from the rotation center satisfies the following relationship:

[0101]

[0102] By combining equations (3)-(10), the angular velocity ω of the welding robot vehicle body, the speed V 右 of the right drive wheel, and the speed V h of the sliding block can be obtained as follows:

[0103]

[0104]

[0105]

[0106] According to the calculated drive wheel speed and vehicle body speed, the robot vehicle body and the sliding block are cooperatively controlled to complete the trajectory planning of the 45° trajectory after the right-angle weld.

[0107] Figure 8 The following are the results of experimental verification of the right-angle weld using the method described in this embodiment. From Figure 8 it can be seen that the robot welding trajectory planned according to the method of the present application has high accuracy.

[0108] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for real-time trajectory planning of right-angle welds under offset welding torch installation conditions, characterized in that, Includes the following steps: Step S1. Initialize the welding robot board; Step S2. The host computer obtains the modified trajectory planning data; The process of modifying the trajectory planning data is as follows: Step S21. Determine the hysteresis angle θ Size 1; By measuring the distance between the rotation center and the welding torch d OA The distance between point A when the welding torch is initially positioned at the weld and point B when the welding torch is again positioned at the weld. d AB ,but θ 1. d OA as well as d AB Satisfying the formula: （1）； Step S22. Based on the obtained hysteresis angle φ1, establish a relationship between the slider and the welding robot body speed and the welding speed, where the welding robot body speed along the radial direction is... and the rotation speed of the welding robot body Welding speed of welding robots The relationship between them is as follows: （2）； （3）； Step S23. Based on the relationship between the hysteresis angle φ1 obtained in step S21 and the formula given in step S22, and in combination with the actual welding requirements, modify the trajectory planning data of the welding robot. Step S3. The welding robot starts tracking. During the tracking process, the host computer periodically collects data from the angle sensor and the laser rangefinder. The host computer performs online trajectory planning for the welding robot based on the real-time collected data. Step S4. Check if the right-angle weld is finished.

2. The real-time trajectory planning method for right-angle welds under the offset installation state of a welding torch as described in claim 1, characterized in that, In step S3, the host computer performs online trajectory planning for the welding robot based on the real-time collected data. The trajectory planning for the welding robot body rotation angle between 0° and 45° is as follows: From 0° to When the angle is adjusted, the slider is in a retracting state. The following plan will first cover the angle from 0° to... The speed of the angle welding robot body and the slider: Let the angle through which the welding robot body rotates during the sampling period of the host computer be . Then the following relationship exists: （4）； （5）； Due to the angular velocity of the drive wheels of the welding robot's rotating body. If the angular velocity at the welding torch is equal to the angular velocity at the welding torch, then the following relationship holds: （6）； （7）； In the above formula, b is the distance from the center of the right drive wheel to the center of rotation, and R is the distance from the welding torch to the center of rotation; By combining equations (4) and (7), the linear velocity of the right drive wheel can be obtained. : （8）； Since the movement of the welding torch in the direction perpendicular to the weld seam can only be achieved by the movement of the lateral slider, the velocity V of the welding torch in the radial direction is... R The speed of the slider due to the contraction or extension of the welding torch slider. Different, slider speed With the radial velocity V R There is a relation: （9）； The slider velocity can be obtained by combining equations (5) and (9). （10）； Similarly, By planning within a 45° range, the slider speed can be obtained. and the linear velocity of the right drive wheel : （11）； （12）； Based on the calculated slider speed and the linear velocity of the right drive wheel Perform coordinated control of the robot body and slider to complete the trajectory planning for the first 45° of the right-angle weld.

3. The real-time trajectory planning method for right-angle welds under the offset installation state of the welding torch as described in claim 2, characterized in that, In step S3, the host computer performs online trajectory planning for the welding robot based on the real-time collected data. The trajectory planning for the welding torch when it is located on the rotation center line is as follows: During the 45° rotation of the vehicle body, the welding torch moves a distance L. y Equal to the distance L between the welding torch at the initial position and the center of rotation x When the welding torch lags behind the center of rotation, due to the welding torch lags behind the center of rotation... The angle causes the welding torch to move a distance L. y Not equal to L x Then at this time L x L y The following relationship is satisfied between them: （13）； In the above formula, L y L is the longitudinal distance of the welding torch relative to the center of rotation. x The horizontal distance of the welding torch relative to the center of rotation. The hysteresis angle of the welding torch relative to the center line of rotation; By combining equations (11), we obtain L. x Satisfying the relation: （14）； Therefore, when the welding robot body rotates between 45° and 90°, the distance R between the welding torch and the center of rotation satisfies the following relationship: （15）； By combining equations (3)-(10) and (13)-(15), the angular velocity of the welding robot's rotating drive wheel can be obtained. The linear velocity V of the right drive wheel 右轮 Slider speed as follows: （16）； （17）； （18）； Based on the calculated angular velocity of the welding robot's rotating drive wheels The linear velocity V of the right drive wheel 右轮 and slider speed Perform coordinated control of the robot body and slider to complete the trajectory planning for the 45° section after the right-angle weld.

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