CN101961819A - Device for realizing laser welding and seam tracking and control method thereof - Google Patents

Abstract

The invention relates to a device for realizing laser welding and seam tracking and a control method thereof. The device of the invention comprises an image collecting and processing unit for collecting and processing the image data of laser welding and seam characteristics and outputting the seam position information, a motion control unit for receiving the seam position information and transmitting a motion control command to a motion shaft actuating mechanism, and an upper parameter setting and control unit for setting the parameters and being respectively connected with the image collecting and processing unit and the motion control unit in a communication mode. The method of the invention comprises the following steps: setting the parameters by utilizing the upper parameter setting and control unit; collecting and processing seam images to obtain the seam image data; caching and calibrating the seam image data, and determining the offset of a welding gun; carrying out filtering, fitting and track planning on tracking tracks by utilizing a motion controller in the motion control unit; and transmitting the result to a motion shaft driver. The invention can be suitable for various seam types and techniques and has the advantages of good generality, strong flexibility, high independence, high precision, accurate positioning, strong adaptability, and the like.

Description

A kind of laser weld weld joint tracking implement device and control method thereof

Technical field

Vision measurement and smart motion control technology in the present invention and the robot manufacturing field, a kind of specifically laser weld weld joint tracking implement device and control method thereof.

Background technology

At present, in the welding procedure of making robot is produced, generally adopt the mode of control manually, robot teaching or off-line programing to carry out path planning and movement programming, just simply repeat predefined action in the welding process.But in laser weld,, therefore higher requirement has been proposed laser welding apparatus because it has the technological requirement of high-speed, high precision.

In existing weld joint tracking implementation, the general sensors such as machinery, electromagnetism, vision that adopt provide weld seam information, are handled by system, realize welding torch position control.But such seam tracking system generally seals, and is sensor and Processing Algorithm at particular system exploitation, lacks general, seam tracking system in real time flexibly and independently.External had the product of ripe laser weld seam tracking system of part, but the comparison system performance is each has something to recommend him, be difficult on the precision and speed on satisfy the requirement of laser weld high-speed, high precision simultaneously, and system architecture is huge, it is complicated to constitute.

Summary of the invention

At above shortcomings part in the prior art, the technical problem to be solved in the present invention provides a kind of have precision height, location standard, adaptable laser weld weld joint tracking implement device and control method thereof.

For solving the problems of the technologies described above, the technical solution used in the present invention is:

A kind of laser weld weld joint tracking of the present invention implement device comprises:

IMAQ and processing unit, welding seam position information is handled and exported to the view data of collection laser weld weld seam feature to this view data;

Motion control unit receives above-mentioned welding seam position information and carries out analyzing and processing, sends motion control instruction to kinematic axis executing agency;

Upper-layer parameters is provided with and control module, and IMAQ and processing parameter, motion control parameter are set, and carries out communication and is connected with IMAQ and processing unit, motion control unit respectively.

Described IMAQ and processing unit comprise LASER Light Source, optical module and smart camera, and wherein a word line laser of LASER Light Source generation reflects by welding work pieces, is gathered by smart camera through optical module; Described laser source wavelength is 660nm, and power is that 50mw～100mw is adjustable; Optical filter in the described optical module can see through the light wave of wavelength 660nm.

Described motion control unit comprises motion controller, kinematic axis driver and kinematic axis executing agency, wherein:

Motion controller is the control core with DSP, links to each other by the CAN bus with the smart camera of IMAQ and processing unit, and the positional information of its input is analyzed, calculated, and obtains the control position information of kinematic axis executing agency;

The kinematic axis driver, the control position information of reception motion controller exports kinematic axis executing agency to, and compensating motion is corrected in the tracking of final welding gun butt welded seam position of realizing.

The control method of a kind of laser weld weld joint tracking of the present invention implement device is characterized in that may further comprise the steps:

Beginning is provided with parameter by upper-layer parameters setting and control module;

Gather weld image in real time by IMAQ and processing unit, and carry out image algorithm and handle and to obtain the weld image data;

With weld image data buffer memory, the rower of going forward side by side is handled surely, determines the welding gun side-play amount of current collection image correspondence;

Motion controller in the motion control unit carries out filtering, match and the trajectory planning of pursuit path according to above-mentioned welding gun side-play amount;

Aforementioned calculation result gives the kinematic axis driver kinematic axis executing agency is implemented control.

Described parameter comprises filtering, the match control algolithm parameter of laser instrument light intensity regulating parameter, workpiece parameter, image processing algorithm parameter and pursuit path computational process.

Described image algorithm processing combines by FPGA hardware programming and dsp software programming and realizes, wherein realizes the image preprocessing process by the FPGA hardware programming, may further comprise the steps:

Window to gathering weld image, obtain area-of-interest;

The region of interest area image is carried out medium filtering obtain image after the filtering;

Image after the filtering is carried out the binary picture image intensifying to be handled;

Image after the binaryzation being implemented the mathematical morphology of expansion and corrosion handles;

Image after expansion and the corrosion is carried out edge extracting;

Image behind the edge extracting is carried out center line to be extracted;

Realize the feature point extraction process by the dsp software programming, may further comprise the steps:

Adopt least square method to carry out fitting a straight line to handle the center line that obtains by FPGA;

By finding maximum corner position to find characteristic point, realize feature point extraction.

The welding gun side-play amount of described definite current collection image correspondence may further comprise the steps:

Optical plane uniformly-spaced is divided into rectangular mesh by density, and each grid vertex is the characteristic point of prior demarcation;

In as the plane, have and the corresponding grid of optical plane, carry out the actual measurement of grid each point, obtain image coordinate (u, the v) pairing optical plane physical coordinates (x on irregular grid summit in the picture plane by Position Control _w, y _w, z _w), obtain corresponding relation database table;

Handle the weld bead feature points information that obtains for above-mentioned image, be any to be calibrated some P (u in the picture plane, v), go out its physical coordinates, obtain the three-dimensional coordinate P (x of actual welds point by the little quadrilateral mesh interpolation calculation of surrounding this point to be calibrated in the above-mentioned related table of having set up _w, y _w, z _w).

By three-dimensional coordinate (x, y, z) and camera and welding gun physical location relation determine to be fixed in the tracking displacement of the welding gun butt welded seam in the kinematic axis executing agency.

The filtering of described pursuit path, match are also calculated trace point and movement instruction planning function in real time, and implementation procedure may further comprise the steps:

Motion controller adopts the welding gun offset information of collection of timer interrupt mode reading images and processing unit;

The welding gun offset information that apparent distance scope obtains before the motion controller pursuit path filtration module is imported information as filtering, filtering parameter (as intermediate value or mean filter algorithm and 3 or 5 filtering parameters) by the host computer transmission carries out the selection of algorithm and parameter, the length of 2 times of forward sight distances as filter window is set, finish filtering and calculate, output is through the welding gun side-play amount after the filtering;

The pursuit path fitting module with the output quantity of filtration module as input, fitting parameter by host computer transmission carries out the selection of approximating method (as least square or cubic spline match) and match window size (as parameter setting or forward sight apart from the multiple setting), finish The Fitting Calculation, and the division that the line segment after the match is controlled the welding gun side-play amount according to the time beat synchronous with gathering beat is calculated in real time;

The output quantity of tracking trajectory planning module after with The Fitting Calculation by leading deviation computational methods, calculated the rectification side-play amount that current welding gun need be followed the tracks of compensating motion as input, and carries out movement instruction planning according to the control beat of 10 milliseconds of predetermined multiples.

Described leading deviation computational methods are as follows:

When welding gun forward travel distance during smaller or equal to L, welding gun from the position " n " correction value of " n+1 " is to the position:

${\mathrm{Delta}}_{n+1}={\mathrm{Dist}}_{n+1}-\underset{p=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n+1\≤M,n,p\⊆Z);$ The welding gun forward travel distance is smaller or equal to L; Wherein:

M is the forward sight distance L length welding gun beat number that advances, and promptly welding gun begins the processing picture number before the real-time tracking;

The advance last beat number of control beat of welding gun when n is the leading deviate of current calculating;

P is a certain beat before the current location;

Dist _N+1The distance that departs from initial position for the current location welding gun;

Delta _pCorrection value for the last relatively beat of a certain beat horizontal level before the current location;

Delta _N+1Correction value for the last relatively beat of current location position.

Back, welding gun in-position " M " correction value computing formula is:

${\mathrm{Delta}}_{M+n+1}={\mathrm{Dist}}_{M+n+1}-\underset{p=n+2}{\overset{M+n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n,p\⊆Z);$

Wherein:

M, the p implication is the same;

N controls the last beat number of beat for beginning from initial position to advance apart from the current location welding gun that begins length after to calculate through first forward sight;

Dist _M+n+1The distance that departs from initial position for the current location welding gun;

Delta _pCorrection value for the last relatively beat of a certain beat horizontal level before the current location;

Delta _M+n+1Correction value for the last relatively beat of current location position.

The present invention has following beneficial effect and advantage:

1. use the inventive method and device can adapt to multiple weld seam type and technology, locate in the time of can realizing the high-precision real of position while welding, have advantages such as versatility is good, flexibility is strong and independence is high and precision is high, the location accurate, adaptability is strong.The present invention can adapt to V-arrangement interface, overlap joint and etc. multiple weld seam types such as slab, unequal thickness plate butt joint, gather the laser welded seam image, extract the weld bead feature points position; Smart camera provides network interface to realize that host computer is provided with the running parameter of camera, and the weld joint tracking position data that provides the CAN communication interface to carry out after image is handled is transmitted; Motion control DSP has to the simulated power control interface of linear laser device and to the signal interactive interface of PLC; After finishing parameter and be provided with at a kind of operating mode, system can break away from host computer and independently finish automatic weld joint tracking.

2. the present invention is directed to V-arrangement interface, overlap joint with etc. the different operating modes of multiple weld seam types such as slab, unequal thickness plate butt joint designed different parameters and be used for the weld image processing module, and according to smart camera and the connected mode that connects firmly of following the tracks of executing agency, developed leading deviation Weld Seam Tracking Control algorithm, to adapt to the weld joint tracking requirement of multiple welds types operating mode.

Description of drawings

Fig. 1 is the structured flowchart of laser weld weld joint tracking implement device of the present invention;

Fig. 2 is the inventive method control flow chart;

Fig. 3 is the structured flowchart of smart camera in the laser weld weld joint tracking implement device;

Fig. 4 is the functional flow diagram of smart camera in the laser weld weld joint tracking implement device;

Fig. 5 is a motion control unit functional flow diagram in the laser weld weld joint tracking implement device;

Fig. 6 is the calibrating function schematic diagram of smart camera in the laser weld weld joint tracking implement device;

Fig. 7 is that laser weld weld joint tracking implement device switch board is arranged schematic diagram;

Fig. 8 is an embodiment of the invention structural representation;

Fig. 9～Figure 15 handles treatment effect figure ()～(seven) of each step for image of the present invention;

Figure 16 follower and weld seam relative position schematic diagram.

The specific embodiment

Apparatus of the present invention structure comprises as shown in Figure 1:

IMAQ and processing unit, welding seam position information is handled and exported to the view data of collection laser weld weld seam feature to this view data;

Motion control unit receives above-mentioned welding seam position information and carries out analyzing and processing, sends motion control instruction to kinematic axis executing agency;

Upper-layer parameters is provided with and control module, and IMAQ and processing parameter, motion control parameter are set, and carries out communication and is connected with IMAQ and processing unit, motion control unit respectively.

Described IMAQ and processing unit comprise LASER Light Source, optical module and smart camera, and wherein a word line laser of LASER Light Source generation reflects by welding work pieces, is gathered by smart camera through optical module.

Described motion control unit comprises motion controller, kinematic axis driver and kinematic axis executing agency, wherein:

Motion controller is the control core with DSP, links to each other by the CAN bus with the smart camera of IMAQ and processing unit, and the positional information of its input is analyzed, calculated, and obtains the control position information of kinematic axis executing agency;

The kinematic axis driver receives the control position information of motion controller, exports to kinematic axis executing agency, thereby finishes the tracking rectification compensating motion of the welding gun butt welded seam position that the present invention institute will finally realize.

As shown in Figure 8, the smart camera 3 in the system connects firmly with following the tracks of executing agency 10, and welding welding-gun 9 connects firmly with executing agency 10.Semiconductor one word line laser instrument 1, optical filter 2 and smart camera 3 have been encapsulated in IMAQ and the processing unit 4.The 1st perforate 6 of outer cover top, be used to draw the connection of power line, laser power analog control signal line and the smart camera CAN Bus and the ethernet lan of laser instrument and smart camera, the 1st, 2 perforates 7,8 are as the going out of IMAQ and processing unit 4 air cooling systems, air intake.Single-piece frame and welding gun 9 are rigidly connected, mounting distance accurately guarantees by installing hole, be and integral body connected in the executing agency 10, thereby executing agency 10 can realize the adjustment of welding gun 9 with respect to position while welding perpendicular to the bead direction motion, in the present embodiment with what direction? be defined as the Y direction.Executing agency 10 passes through support 11 overall fixed on welding equipment.As shown in Figure 7, motion control unit and upper-layer parameters setting and control module are integrated to be installed in the switch board, wherein the kinematic axis driver in the motion control unit is that servo-driver is installed in the switch board below, the industrial control computer of motion controller DSP2812 and employing Windows system is the top that upper-layer parameters setting and control module are installed on switch board respectively, spare interface connects smart camera cable in IMAQ and the processing unit 4, outside PLC (be used for link to each other with other system realization external control) and system's power supply etc., the switch board guidance panel is equipped with display and various indicator lamp, button and emergency stop switch.

The laser beam that semiconductor one word line laser instrument 1 sends produces the structured light plane, shines the welding work pieces surface, forms the feature laser stripe of weld seam 5, laser focus is 110mm, the focal position live width is 0.044mm, and power is 50～100mw, and wavelength is 660nm.Optical filter 2 can be through the light wave of wavelength 660nm.Smart camera 3 is gathered the laser stripe image that is formed by laser instrument 1.

The laser weld seam tracking system is always worked flow process as shown in Figure 2, may further comprise the steps:

Beginning is provided with parameter by upper-layer parameters setting and control module;

Gather weld image in real time by IMAQ and processing unit, and carry out image algorithm and handle and to obtain the weld image data;

With weld image data buffer memory, the rower of going forward side by side is handled surely, determines the welding gun side-play amount of current collection image correspondence;

Motion controller in the motion control unit carries out filtering, the match of pursuit path and calculates the planning of trace point and movement instruction in real time according to above-mentioned welding gun side-play amount;

Aforementioned calculation result gives the kinematic axis driver kinematic axis executing agency is implemented control.

At first, parameter is set, comprises 1 by upper-layer parameters setting and control module) laser instrument light intensity regulating parameter, be transferred to slave computer DSP2812 by serial ports, by its simulation control interface the laser instrument light intensity is being controlled; 2) selection of interface shapes such as V word interface, butt joint, overlap joint and etc. the selection of slab, unequal thickness plate welding condition, and the relevant parameter of the size of windowing, filtering scheduling algorithm is transferred to smart camera by the lan network interface; 3) set the filtering of tracking system pursuit path, fitting parameter, be transferred to the DSP2812 motion control unit by serial ports.

Then, gather weld image in real time, and carry out image algorithm and handle and to obtain the weld image data by IMAQ and processing unit; With weld image data buffer memory, the rower of going forward side by side is handled surely, determines the welding gun side-play amount of current collection image correspondence, and detailed process is as follows:

IMAQ and processing unit are gathered in real time and are carried out the weld image processing capacity and finished by smart camera, the composition structure of smart camera as shown in Figure 3, the course of work as shown in Figure 4, now specifically describe as follows: the optical pickocff of camera carries out IMAQ according to certain beat, beat control, relevant parameters such as the time for exposure and the size of windowing are finished by the LAN LAN interface by host computer and are preestablished, FPGA reads and gathers the original image that is stored in " frame buffer ", and carry out the hard-wired image processing function of FPGA, comprise and windowing, filtering, binaryzation, expand and corrosion, edge extracting and axis of a weld extract, image processing effect is seen Fig. 9～15, wherein Fig. 9 is the original weld image that has the sign of windowing, Figure 10 is the region of interest area image after windowing, Figure 11 is the image of filtering after handling, Figure 12 is the image after the binary conversion treatment, Figure 13 is the image after expansion and the corrosion treatment, Figure 14 is the image of edge extracting after handling, and Figure 15 extracts image after the processing for center line.The axis of a weld image data storage of extracting is in " image buffer storage ", magazine DSP takes out the axis of a weld view data and is stored in " synchronous DRAM " that is associated with it from " image buffer storage ", and it is carried out the position while welding feature point extraction handle (as shown in figure 15), data are stored in " read-only storage ".Simultaneously, the DSP butt welded seam view data in the smart camera is demarcated processing, determines the side-play amount of the welding gun phase butt welded seam of current collection picture position correspondence, sends the welding gun side-play amount to motion control unit by the CAN Bus interface at last.

Wherein, calibration principle figure as shown in Figure 6, process is as follows:

Optical plane uniformly-spaced is divided into rectangular mesh by certain density, and each grid vertex is the characteristic point of prior demarcation, has in as the plane and the corresponding grid of optical plane, because lens distortion, these grids become irregular quadrangle; By carrying out a series of accurate experiment measurings, can obtain image coordinate (u, the v) pairing optical plane physical coordinates (x on irregular grid summit in the picture plane _w, y _w, z _w), obtain corresponding relation database table; Handle the weld bead feature points information that obtains for above-mentioned image, be any to be calibrated some P (u in the picture plane, v), can go out its physical coordinates, obtain the three-dimensional coordinate P (x of actual welds point by the little quadrilateral mesh interpolation calculation of surrounding this point to be calibrated in the above-mentioned related table of having set up _w, y _w, z _w).

Before system starts working, need carry out Zero calibration by accurate measurement, promptly demarcate certain any physics corresponding relation on the dead-center position executing agency of regulation and picture plane.Because smart camera is fixed on executing agency and welding gun, therefore, can will correspond on the welding gun physical location as certain some position on the plane by this corresponding relation.

Then, the DSP2812 motion controller in the motion control unit carries out filtering, the match of pursuit path and calculates the planning of trace point and movement instruction in real time according to above-mentioned welding gun side-play amount;

The amount that kinematic axis executing agency implements control is the rectification side-play amount that current welding gun need be followed the tracks of compensating motion, be that welding gun advances to the correct amount that next position is needing perpendicular to bead direction from a position, and processing result image embodies is to obtain image to be fixed in the welding gun in the kinematic axis executing agency and the relative displacement of weld seam constantly, be not the motion control correct amount of above-mentioned needs, so must carry out motion planning to the result of IMAQ and processing unit gained.

Before motion planning,, need earlier the pursuit path data to be carried out filtering, match and calculated trace point in real time in order to guarantee motion stabilization.

The DSP motion controller adopts the welding gun offset information of collection of timer interrupt mode reading images and processing unit, and the timing beat is designed to 10 milliseconds;

Apparent distance scope is (in Fig. 8 before the DSP motion controller pursuit path filtration module (as shown in Figure 5), laser stripe 5 and the vertical range D of welding gun 9 between the projection on the workpiece) the welding gun offset information that obtains imports information as filtering, filtering parameter (as intermediate value or mean filter algorithm and 3 or 5 filtering parameters) by host computer (being upper-layer parameters setting and control module) transmission carries out the selection of algorithm and parameter, the length of 2 times of forward sight distances as filter window is set, finish filtering and calculate, output is through the welding gun side-play amount after the filtering.

The output quantity of pursuit path fitting module (as shown in Figure 5) is as input, fitting parameter by host computer transmission carries out the selection of approximating method (as least square or cubic spline match) and match window size (as parameter setting or forward sight apart from the multiple setting), finish The Fitting Calculation, and the division that the line segment after the match is controlled the welding gun side-play amount according to the time beat synchronous with gathering beat is calculated in real time.

Tracking trajectory planning module (as shown in Figure 5) with the output quantity after the The Fitting Calculation as input, calculate the rectification side-play amount that current welding gun need be followed the tracks of compensating motion by leading deviation computational methods, and carry out movement instruction planning according to the control beat of 10 milliseconds of predetermined multiples.Leading deviation computational methods schematic diagram as shown in figure 16, detailed process is as follows:

Because camera is positioned at the place ahead of welding gun, so the tracking lag of welding gun butt welded seam is in image processing process, the picture number that begins to handle the real-time tracking to welding gun from camera collection first width of cloth image, it is the picture number of gathering in the forward sight distance range, can adopt following formula to calculating, as shown in figure 16, be the deviation schematic diagram of weld seam and welding gun.

$M=\frac{L}{v\·t_p}---\left(1\right)$

In the formula: M is for handling picture number; L is a distance between welding gun and the camera, i.e. the forward sight distance; V is a speed of welding; t _pFor handling the frame weld image time.

The meaning of following formula: because welding gun just begins to carry out real-time tracking after will arriving the camera initial position, promptly pass through the length L of forward sight distance, so at first calculate from the welding gun begin column and go to welding gun arrival camera initial position required time (L/v), handle the used time t of a two field picture with this time divided by smart camera again _p, i.e. (L/ (vt _p)), obtain the processing picture number (M) before welding gun begins real-time tracking.

In actual applications, what the present invention was concerned about is that welding gun advances to the correct amount that next position needs in the horizontal direction from a position, and the processing result image embodiment is the relative position that obtains this moment welding gun of image and weld seam, be not the correct amount that the present invention needs, so must the result that image is handled gained be adjusted.The welding gun of the processing result image of position if " n " and the distance Dist of weld seam center _nExpression, from the position " n-1 " to the position horizontal direction correction value Delta of " n " _nExpression.Dist _nAnd Delta _nBe signed number, the Dist when the definition weld seam is positioned at the welding gun right side _nAnd Delta _nFor just, the Dist of correspondence when being positioned at the welding gun left side _nAnd Delta _nFor negative.

By primary condition as can be known, to advance to camera initial position (being made as a reset) preceding when welding gun, do not carry out the position adjustment of any horizontal direction, when arriving the camera initial position, welding gun is over against weld seam, and welding gun advances to the required horizontal level correction value (Delta of a set by the position reset ₁) calculate the deviate Dist of gained before equaling ₁And advance to position " 2 " horizontal direction correction value from the position set no longer is the processing result image Dist that obtains ₂, must correct this result, it is as follows to correct formula:

Delta ₂＝Dist ₂-Delta ₁ (2)

" 2 " correction value of " 3 " is welding gun to the position from the position:

Delta ₃＝Dist ₂-Delta ₁-Delta ₂ (3)

The rest may be inferred, from the position " n " correction value of " n+1 " is to the position:

${\mathrm{Delta}}_{n+1}={\mathrm{Dist}}_{n+1}-\underset{p=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n+1\≤M,n,p\⊆Z)---\left(4\right)$

Top formula is applicable to the situation of welding gun forward travel distance smaller or equal to L.

When welding gun from the position " M " (position " M " expression welding gun begins first forward sight distance and position of beginning from initial position before the real-time tracking here) when advancing to position " M+1 ", situation changes.The camera weld image that " M+1 " locates to obtain in the position is corresponding to welding gun (being the camera center) translation Delta in the horizontal direction ₁Distance, promptly this moment image horizontal reference be the abscissa of position set, rather than the abscissa of reset before this, so the welding gun correction value that " M " advances to position " M+1 " from the position is:

${\mathrm{Delta}}_{M+1}={\mathrm{Dist}}_{M+1}-\underset{p=2}{\overset{M}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(p\⊆Z)---\left(5\right)$

The processing result image of promptly using position " M+1 " to locate deduct welding gun from the position set to the position " M " displacement sum in the horizontal direction be exactly from the position " M " to the position horizontal direction correction value of " M+1 ".

In like manner, the weld image that the position " M+2 " that obtains when welding gun in-position " 2 " is located, and obtain corresponding Dist by image processing algorithm _M+2, for obtain from the position " M+1 " to the position correction value Delta of " M+2 " _M+2, need be from Dist _M+2Deduct from the position " 2 " to the position " M+1 " welding gun displacement sum in the horizontal direction, that is:

${\mathrm{Delta}}_{M+2}={\mathrm{Dist}}_{M+2}-\underset{p=3}{\overset{M+1}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(p\⊆Z)---\left(6\right)$

So the general correction value computing formula after welding gun in-position " M " is:

${\mathrm{Delta}}_{M+n+1}={\mathrm{Dist}}_{M+n+1}-\underset{p=n+2}{\overset{M+n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n,p\⊆Z)---\left(7\right)$

Above (4), (7) two formula be applicable to all places relation that welding gun and weld seam exist, be above-mentioned leading deviation computational methods.

At last, above-mentioned movement instruction is given the kinematic axis driver by the pwm signal of motion controller DSP2812 kinematic axis executing agency is implemented the motion of control realization weld joint tracking.

Claims (11)

1. laser weld weld joint tracking implement device is characterized in that comprising:

IMAQ and processing unit, welding seam position information is handled and exported to the view data of collection laser weld weld seam feature to this view data;

Motion control unit receives above-mentioned welding seam position information and carries out analyzing and processing, sends motion control instruction to kinematic axis executing agency;

Upper-layer parameters is provided with and control module, and IMAQ and processing parameter, motion control parameter are set, and carries out communication and is connected with IMAQ and processing unit, motion control unit respectively.

2. by the described laser weld weld joint tracking of claim 1 implement device, it is characterized in that: described IMAQ and processing unit comprise LASER Light Source, optical module and smart camera, wherein a word line laser of LASER Light Source generation reflects by welding work pieces, is gathered by smart camera through optical module.

3. by the described laser weld weld joint tracking of claim 2 implement device, it is characterized in that: described laser source wavelength is 660nm, and power is that 50mw～100mw is adjustable.

4. by the described laser weld weld joint tracking of claim 2 implement device, it is characterized in that: the optical filter in the described optical module can see through the light wave of wavelength 660nm.

5. by the described laser weld weld joint tracking of claim 1 implement device, it is characterized in that: described motion control unit comprises motion controller, kinematic axis driver and kinematic axis executing agency, wherein:

Motion controller is the control core with DSP, links to each other by the CAN bus with the smart camera of IMAQ and processing unit, and the positional information of its input is analyzed, calculated, and obtains the control position information of kinematic axis executing agency;

The kinematic axis driver, the control position information of reception motion controller exports kinematic axis executing agency to, and compensating motion is corrected in the tracking of final welding gun butt welded seam position of realizing.

6. the control method of a laser weld weld joint tracking implement device is characterized in that may further comprise the steps:

Beginning is provided with parameter by upper-layer parameters setting and control module;

Gather weld image in real time by IMAQ and processing unit, and carry out image algorithm and handle and to obtain the weld image data;

With weld image data buffer memory, the rower of going forward side by side is handled surely, determines the welding gun side-play amount of current collection image correspondence;

Motion controller in the motion control unit carries out filtering, match and the trajectory planning of pursuit path according to above-mentioned welding gun side-play amount;

Aforementioned calculation result gives the kinematic axis driver kinematic axis executing agency is implemented control.

7. by the control method of the described laser weld weld joint tracking of claim 6 implement device, it is characterized in that:

Described parameter comprises filtering, the match control algolithm parameter of laser instrument light intensity regulating parameter, workpiece parameter, image processing algorithm parameter and pursuit path computational process.

8. press the control method of the described laser weld weld joint tracking of claim 6 implement device, it is characterized in that: described image algorithm processing combines by FPGA hardware programming and dsp software programming and realizes, wherein realize the image preprocessing process, may further comprise the steps by the FPGA hardware programming:

Window to gathering weld image, obtain area-of-interest;

The region of interest area image is carried out medium filtering obtain image after the filtering;

Image after the filtering is carried out the binary picture image intensifying to be handled;

Image after the binaryzation being implemented the mathematical morphology of expansion and corrosion handles;

Image after expansion and the corrosion is carried out edge extracting;

Image behind the edge extracting is carried out center line to be extracted;

Realize the feature point extraction process by the dsp software programming, may further comprise the steps:

Adopt least square method to carry out fitting a straight line to handle the center line that obtains by FPGA;

By finding maximum corner position to find characteristic point, realize feature point extraction.

9. by the control method of the described laser weld weld joint tracking of claim 6 implement device, it is characterized in that: the welding gun side-play amount of described definite current collection image correspondence may further comprise the steps:

Optical plane uniformly-spaced is divided into rectangular mesh by density, and each grid vertex is the characteristic point of prior demarcation;

In as the plane, have and the corresponding grid of optical plane, carry out the actual measurement of grid each point, obtain image coordinate (u, the v) pairing optical plane physical coordinates (x on irregular grid summit in the picture plane by Position Control _w, y _w, z _w), obtain corresponding relation database table;

Handle the weld bead feature points information that obtains for above-mentioned image, be any to be calibrated some P (u in the picture plane, v), go out its physical coordinates, obtain the three-dimensional coordinate P (x of actual welds point by the little quadrilateral mesh interpolation calculation of surrounding this point to be calibrated in the above-mentioned related table of having set up _w, y _w, z _w).

By three-dimensional coordinate (x, y, z) and camera and welding gun physical location relation determine to be fixed in the tracking displacement of the welding gun butt welded seam in the kinematic axis executing agency.

10. by the control method of the described laser weld weld joint tracking of claim 6 implement device, it is characterized in that: the filtering of described pursuit path, match are also calculated trace point and movement instruction planning function in real time, and implementation procedure may further comprise the steps:

Motion controller adopts the welding gun offset information of collection of timer interrupt mode reading images and processing unit;

The welding gun offset information that apparent distance scope obtains before the motion controller pursuit path filtration module is imported information as filtering, filtering parameter by the host computer transmission carries out the selection of algorithm and parameter, the length of 2 times of forward sight distances as filter window is set, finish filtering and calculate, output is through the welding gun side-play amount after the filtering;

The pursuit path fitting module with the output quantity of filtration module as input, fitting parameter by the host computer transmission carries out the selection of approximating method and match window size, finish The Fitting Calculation, and the division that the line segment after the match is controlled the welding gun side-play amount according to the time beat synchronous with gathering beat is calculated in real time;

The output quantity of tracking trajectory planning module after with The Fitting Calculation by leading deviation computational methods, calculated the rectification side-play amount that current welding gun need be followed the tracks of compensating motion as input, and carries out movement instruction planning according to the control beat of 10 milliseconds of predetermined multiples.

11. by the control method of the described laser weld weld joint tracking of claim 10 implement device, it is characterized in that: described leading deviation computational methods are as follows:

When welding gun forward travel distance during smaller or equal to L, welding gun from the position " n " correction value of " n+1 " is to the position:

${\mathrm{Delta}}_{n+1}={\mathrm{Dist}}_{n+1}-\underset{p=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n+1\≤M,n,p\⊆Z);$ The welding gun forward travel distance is smaller or equal to L; Wherein:

M is the forward sight distance L length welding gun beat number that advances, and promptly welding gun begins the processing picture number before the real-time tracking;

The advance last beat number of control beat of welding gun when n is the leading deviate of current calculating;

P is a certain beat before the current location;

Dist _N+1The distance that departs from initial position for the current location welding gun;

Delta _pCorrection value for the last relatively beat of a certain beat horizontal level before the current location;

Delta _N+1Correction value for the last relatively beat of current location position.

Back, welding gun in-position " M " correction value computing formula is:

${\mathrm{Delta}}_{M+n+1}={\mathrm{Dist}}_{M+n+1}-\underset{p=n+2}{\overset{M+n}{\mathrm{\Σ}}}{\mathrm{Delta}}_p(n,p\⊆Z);$

Wherein:

M, the p implication is the same;

N controls the last beat number of beat for beginning from initial position to advance apart from the current location welding gun that begins length after to calculate through first forward sight;

Dist _M+n+aThe distance that departs from initial position for the current location welding gun;

Delta _pCorrection value for the last relatively beat of a certain beat horizontal level before the current location;

Delta _M+n+1Correction value for the last relatively beat of current location position.

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