represents a differential coefficient, then K_p、K_i、K_dThe three parameters may directly affect the dynamic tracking performance of the PID tuning model. After a large number of experiments and verifications, the embodiment aims at the requirement of lock-type seam tracking, and the performance of the PID adjustment model is excellent, for example, the requirement of fast response and zero drift is met, the adjustment parameter of the PID adjustment model may be, but is not limited to, the sampling period T being 0.1s, K_p＝2.68、K_i＝0.15、K_dWhen the value is 0.06.

Further, during the crawling of the crawlingwelding robot 10, the vehicle body attitude angle may include a pitch angle and a roll angle, and then the actual implementation process in step S13 may include: and when the roll angle is greater than a first preset value or less than a second preset value, comparing the welding seam trend angle with the pitch angle, and if the welding seam trend angle is greater than the pitch angle, controlling thevehicle body 14 to operate according to a first travel rule so as to realize the adjustment of the tracking angle. Alternatively, the first travel rule may be, but is not limited to, controlling thebody 14 of the crawlingwelding robot 10 to turn left when the pitch angle is less than the weld strike angle, and vice versa to turn right.

And when the pitch angle is larger than a first preset value or smaller than a second preset value, comparing the welding seam trend angle with the rolling angle, and if the welding seam trend angle is larger than the rolling angle, controlling thevehicle body 14 to operate according to a second advancing rule so as to realize the adjustment of the tracking angle. Alternatively, the second travel rule may be, but is not limited to, controlling thebody 14 of the crawlingwelding robot 10 to turn right when the roll angle is less than the weld strike angle, and vice versa to turn left.

In one embodiment, in the PID control model, when T is 0.02s and K_p＝12.0、K_i＝1.14、K_dWhen the value is 1.75; the expression of converting the position information into the strike angle of the welding seam is

Wherein theta is the converted vehicle body attitude angle, 45 degrees is the maximum vehicle body attitude angle, 1024 is the sum of unilateral digital quantity of the linear displacement sensor 16, y is the digital quantity corresponding to the actual position of the position sensor, and y is more than or equal to-1024 and less than or equal to 1024. And calculating a y value through a PID (proportion integration differentiation) regulation model, limiting the value range of the y value, obtaining a vehicle body tracking angle through a position conversion angle formula, and controlling thefirst driving device 12 to drive thevehicle body 14 to carry out position adjustment by the trackingcontroller 11 according to thevehicle body 14 tracking angle, thereby realizing the tracking of thevehicle body 14 on a welding line. It should be noted that, in this practical implementation, the first preset value may include, but is not limited to, 45 degrees, and the second preset value includes, but is not limited to, -45 degrees.

In addition, according to actual requirements, the process of controlling thefirst driving device 12 to drive thevehicle body 14 to perform attitude adjustment by the trackingcontroller 11 includes: assuming that the control mode of the first driving device 12 (e.g. servo driver) is a speed control mode, in which the signal input to thefirst driving device 12 by the trackingcontroller 11 is an analog voltage of-10V to 10V, and the corresponding rotation speed of thefirst driving device 12 is a reverse rotation 3000r/min when the analog voltage is-10V, a rotation speed of 0r/min when the analog voltage is 0V, and a forward rotation 3000r/min when the analog voltage is 10V, it can be seen that the relationship between the analog voltage output to thefirst driving device 12 by the trackingcontroller 11 and the rotation speed of thefirst driving device 12 is: where n is the motor speed in thefirst drive device 12 and x is the analog voltage value output, is (3000 × x)/10. If there is a deviation between the weld midpoint position acquired by the linear displacement sensor 16 and the target value at a certain time, thefirst driving device 12 executes a speed control command under the control of the trackingcontroller 11 until the speed command is 0. Further, in order to effectively improve the accuracy in the vehicle body tracking process, before the step S11-step S13 are executed in the embodiment, as shown in fig. 3, the vehicle body tracking method may further include the step S14-step S16, which is specifically described as follows.

Step S14, receiving the real-time image of the weld groove acquired by theimage acquisition sensor 17 during the tracking process, and calculating to obtain the current midpoint coordinate value of the weld based on the real-time image of the weld groove;

step S15, comparing the transverse coordinate value in the current midpoint coordinate value with a target adjusting value, if the transverse coordinate value and the target adjusting value have deviation, calculating the deviation amount between the transverse coordinate value and the target adjusting value;

step S16, controlling the second driving device 13 to drive the tracking slider 15 to move for position adjustment according to the deviation amount, so as to realize tracking of the middle point position of the weld by theimage acquisition sensor 17 and the linear displacement sensor 16 in the tracking process.

The above-mentioned steps S14 to S16 are for enabling the tracking slider 15 to track the change of the weld coordinates (relative to the coordinates in the relative coordinate system in the tracking controller 11) during the vehicle body tracking process, that is, enabling the linear displacement sensor 16 and theimage capturing sensor 17 mounted on the tracking slider 15 to track the change of the weld coordinates, thereby improving the reliability during the vehicle body tracking process.

In detail, in step S14, the process of the trackingcontroller 11 performing image processing on the real-time weld groove image based on image processing software to obtain the current midpoint coordinate value of the weld in the relative coordinate system may include: and obtaining the image information in the relative coordinate system, and rotating the image information so that the rotated image is perpendicular to a set axis in the relative coordinate system. And analyzing the image information in the rotated relative coordinate system to obtain a current midpoint coordinate value of the welding seam, wherein the current midpoint coordinate value can comprise a transverse coordinate and a longitudinal coordinate. Since the angles of theimage capturing sensor 17 at the time of capturing the weld groove image may be different, the angle of rotating the image may be different in the image processing process, as long as the rotated image is perpendicular to the setting axis. It should be understood that rotating the image information to be perpendicular to the setting axis is only an optional implementation in embodiments of the present invention, and in practical applications, other processing may also be performed on the image information, for example, the image information may be rotated to be parallel to the setting axis. For example, the image information may not be rotated, and the present embodiment is not limited thereto.

Further, the obtaining process of the target adjustment value in steps S15 and S16 may include: when the vehicle body tracking starts, the trackingcontroller 11 controls theimage acquisition sensor 17 to acquire a weld groove image at the current time, calculates a midpoint coordinate value of the weld based on the weld groove image, and extracts an abscissa in the midpoint coordinate value as the target adjustment value. Specifically, in the vehicle body tracking process, the target adjustment value is a target value when adjustment is performed as a PID adjustment model, and the lateral coordinate value in the current midpoint coordinate value is an input amount as the PID adjustment model. It can be understood that the input of the PID control model is actually the deviation amount between the current lateral coordinate value and the target control value, and then the PID control model performs limit and linear conversion on the input deviation amount, converts the digital signal of the deviation amount into an analog signal for speed control of the second driving device 13, and further drives the tracking slider 15 through the second driving device 13 to perform corresponding deviation so as to track the change of the middle point coordinate of the weld joint.

For example, referring to fig. 4, if r (t) is a target adjustment value of the PID adjustment model, and c (t) is a horizontal coordinate value in the current midpoint coordinate value acquired by theimage acquisition sensor 17, the difference e (t) between r (t) and c (t) is used as the input of the PID adjustment model for conversion, and then the trackingcontroller 11 controls the second driving device 13 to drive the tracking slider 15 to move according to the output of the PID adjustment model, so as to drive theimage acquisition sensor 17 and the linear displacement sensor 16 on the tracking slider 15 to move, and compares the real-time weld groove image acquired by theimage acquisition sensor 17 as a feedback with the target adjustment value in the tracking process, thereby achieving the effect of weld tracking.

Further, as can be seen from the descriptions of the above steps S14 to S16, in this embodiment, while the vehicle body is tracked, the change of the midpoint coordinate of the weld is tracked by controlling the tracking slider 15 to perform corresponding offset, so as to improve the reliability in the vehicle body tracking process and ensure the straightness of the tracking track.

Further, according to actual requirements, in order to ensure the reliability of the data collected by each sensor during the vehicle body tracking process, as shown in fig. 5, before the above steps S11-S16 are executed, the vehicle body tracking method may further include the following steps S17-S18.

Step S17, receiving the weld groove image collected and sent by theimage collection sensor 17;

and S18, judging whether the reliability of the current data is greater than a third preset value according to the weld groove image, if so, judging that the vehicle body tracking process can be entered, executing the steps S11-S16, and if not, judging that the reliability of the data collected by the sensor in the current welding environment is poor, thus the vehicle body tracking process cannot be entered.

In detail, the reliability of the current data represents the percentage of accuracy of an output value in the current detection environment, and the value changes with the detected quality of the weld joint, for example, when the shape of the weld joint groove in the weld joint groove image is not obvious or an arc interference condition exists, the reliability value is small. The size of the third preset value can be flexibly set according to actual requirements, for example, the reliability can be but is not limited to 50%.

Further, in actual implementation, in the vehicle body tracking process, it may be further determined whether the variation range of the vehicle body tracking angle received within the preset time duration is smaller than a fourth preset value, if so, it indicates that the tracking effect is good in the process of tracking the weld joint by thevehicle body 14 this time, and the vehicle body attitude angle and the corresponding tracking policy may be stored, so that when next vehicle body tracking of the same type is performed, the stored tracking policy is directly invoked to perform vehicle body tracking.

In summary, the embodiment of the present invention provides a vehicle body tracking method and a crawlingwelding robot 10, wherein the method is based on a multi-sensor fusion technology, detects weld groove information in a tracking process in real time, and adjusts a tracking track of avehicle body 14 in real time according to an offset of a weld midpoint detected by a linear displacement sensor 16 relative to a target midpoint, so as to achieve accuracy and high efficiency of vehicle body tracking. Meanwhile, the accuracy of the vehicle body tracking angle can be effectively ensured through the vehicle body attitude angle acquired by theattitude sensor 18, the track oscillation after the vehicle body tracking is over-adjusted is prevented, the straightness of the vehicle body tracking track is improved, and the welding precision in the welding process of the welding gun is reduced.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus and method embodiments described above are illustrative only, as the flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In addition, the functional modules in the embodiments of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, an electronic device, or a network device) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes. It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is only an alternative embodiment of the present invention and is not intended to limit the present invention, and various modifications and variations of the present invention may occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vehicle body tracking method is executed by a tracking controller on a crawling welding robot, and is characterized in that the crawling welding robot further comprises a vehicle body, a first driving device, an attitude sensor and a linear displacement sensor; the vehicle body tracking method includes:

the tracking controller receives the vehicle body attitude angle acquired and sent by the attitude sensor in the tracking process and the midpoint position information of the welding seam acquired by the linear displacement sensor;

the tracking controller takes the midpoint position information as the input of a PID (proportion integration differentiation) regulation model to calculate the weld joint trend angle of the weld joint;

the tracking controller compares the vehicle body attitude angle with the welding seam trend angle, and controls the first driving device to drive the vehicle body to adjust the tracking angle according to the comparison result so as to realize the tracking of the welding seam by the crawling welding robot.

2. The vehicle body tracking method according to claim 1, wherein the step of calculating the weld bead strike angle θ includes the step of calculating θ ═ (Max/N) × y, where Max is a preset maximum weld bead strike angle, N is a normal number, and y is a digital quantity corresponding to the center position information acquired by the linear displacement sensor calculated by the PID adjustment model, and-N is ≦ y ≦ N.

3. The vehicle body tracking method according to claim 1, wherein the vehicle body attitude angle includes a pitch angle and a roll angle, and the step of comparing the vehicle body attitude angle with the weld strike angle and controlling the first driving device to drive the vehicle body to adjust the tracking angle comprises:

4. The vehicle body tracking method according to claim 3, wherein the first preset value comprises 45 degrees and the second preset value comprises-45 degrees.

5. The vehicle body tracking method according to claim 1, wherein the creep welding machine further comprises a second driving device, a tracking slider, and an image pickup sensor, the image pickup sensor and the linear displacement sensor being mounted to the tracking slider; before the step of receiving the vehicle body attitude angle acquired and transmitted by the attitude sensor in the tracking process is executed, the vehicle body tracking method includes:

6. The vehicle body tracking method according to claim 5, characterized in that the target adjustment value is obtained by:

7. The vehicle body tracking method according to claim 1, characterized in that before the tracking process is started, the vehicle body tracking method further comprises:

8. The vehicle body tracking method according to claim 1, characterized in that the method further comprises:

9. A crawling welding robot is characterized by being used for realizing vehicle body tracking in a welding process and comprising a tracking controller, a first driving device, a second driving device, a vehicle body, a tracking sliding block, an attitude sensor, a linear displacement sensor and an image acquisition sensor;

10. The crawling welding robot of claim 9, wherein the image acquisition sensor comprises one of a CCD sensor, a CMOS sensor, a structured light sensor.