In robotic laser welding, the vision system is commonly used for workpiece recognition, weld seam positioning, position deviation detection, and other functions. When the vision system fails, positioning shifts, the camera image becomes abnormal, or the relationship between the vision coordinates and robot coordinates changes, the robot may fail to locate the correct welding position. This can result in weld deviation, production interruptions, or even workpiece and equipment collisions.

If professional service support is temporarily unavailable, basic troubleshooting and temporary calibration can sometimes help restore production. However, temporary calibration should mainly be used for minor and stable positioning deviations. If the problem involves the camera, robot, laser welding head, controller, or safety system, professional technical support is recommended rather than unauthorized adjustment.

1. Why Does a Robotic Laser Welding Vision System Fail?

A typical robotic laser welding vision system may include an industrial camera, lens, lighting source, vision software, communication module, and robot coordinate system.

Common causes of vision positioning problems include:

• Dust or oil contamination on the camera lens

• Changes in workpiece position

• Significant changes in ambient lighting

• Slight movement of the camera mounting position

• Incorrect vision parameters

• Abnormal calibration data

• Changes in the relationship between vision and robot coordinates

• Communication problems

• Camera or vision controller faults

Therefore, when the vision system stops working correctly, the first step should be determining whether the problem is related to the image, recognition process, or coordinate system.

2. Step One: Confirm Whether the Vision System Has Actually Failed

When the welding position suddenly shifts, do not immediately modify the robot program. First check the current status of the vision system.

Check the Camera Image

Open the vision software or monitoring interface and confirm whether the workpiece can be displayed correctly.

If the image is completely black, distorted, or the camera cannot connect, check the camera power supply and communication connection first instead of performing coordinate calibration.

Check the Lens and Protective Glass

Laser welding produces smoke, dust, and metal particles. Contamination on the lens or protective glass can affect workpiece recognition.

Clean the relevant optical components according to the equipment manufacturer's maintenance instructions.

Check Workpiece Position

Confirm whether the workpiece is positioned in the same way as during normal production.

A change in fixture or workpiece position can cause the vision system to identify a different location.

Check the Recognition Result

If the camera image is normal but the detected position is incorrect, further inspection of the vision parameters and coordinate relationship may be required.

3. Step Two: Clean the Lens and Check Recognition Again

Some vision positioning problems are not caused by calibration data but by contamination in the camera's field of view.

Before cleaning, follow the equipment safety procedures and ensure that the relevant equipment is stopped.

Check:

• Industrial camera lens

• Protective glass

• Lens surroundings

• Camera mounting bracket

• Obstructions in the camera field of view

After cleaning, run the vision recognition process again using the same standard workpiece.

If recognition returns to normal, there is usually no need to modify the vision calibration parameters.

4. Step Three: Check Whether the Camera Position Has Changed

If the camera image looks normal but the detected position has shifted, check the physical camera installation position.

For example, suppose the vision system previously identified the weld center correctly, but all workpieces now show a consistent offset in the same direction.

In this case, check:

• Camera mounting bracket

• Camera fixing screws

• Lens position

• Laser welding head position

• Robot end-effector position

• Workpiece fixture position

If the camera has physically moved, the original calibration relationship may no longer be accurate.

Do not simply compensate for the error by modifying robot coordinates. Otherwise, the system may become more difficult to recalibrate later.

5. Step Four: Use a Standard Workpiece for Temporary Calibration

If the vision system can capture images and recognize the workpiece normally, but there is a small and consistent coordinate deviation, a standard workpiece or calibration target can be used for basic calibration.

The general process is:

Fix the standard target → Perform visual recognition → Obtain the vision coordinates → Compare them with the actual robot coordinates → Identify the deviation → Perform calibration according to the equipment procedure.

For example, if the vision system consistently detects the correct reference point but the robot moves to a location with a small fixed offset, the X and Y deviations can be evaluated.

For small, stable deviations, follow the manufacturer's specified calibration procedure.

Do not randomly change vision parameters or robot coordinates based on experience alone. Vision systems, robot controllers, and software structures differ between manufacturers.

6. Step Five: Check Whether Vision and Robot Coordinates Match

The positioning process of a robotic laser welding machine involves the conversion between different coordinate systems.

A simplified relationship can be understood as:

Camera Coordinates → Workpiece Coordinates → Robot Coordinates → Laser Welding Position

If one part of this coordinate relationship changes, the robot may correctly identify the workpiece but still weld at the wrong location.

For example, if the vision system identifies a weld seam correctly but the robot consistently moves to an offset position, the vision-to-robot coordinate transformation should be checked.

If the equipment provides an automatic calibration function, follow the machine's calibration procedure.

If automatic calibration is unavailable, professional personnel with experience in robotics and machine vision should perform the calibration.

7. Step Six: Check Whether Vision Parameters Were Accidentally Changed

Another common situation is:

The vision hardware is working normally, but a vision program parameter has been changed.

Potentially affected parameters include:

• Exposure

• Gain

• Detection threshold

• Recognition region

• Edge detection settings

• Template parameters

• Product program selection

If the system worked normally before a product change, shift change, or software adjustment, check whether any vision settings were modified.

For verified production programs, it is recommended to maintain backups and establish appropriate access permissions to prevent accidental changes to critical parameters.

8. Why Should You Avoid Simply Modifying the Robot Welding Program?

This is a common mistake when troubleshooting vision positioning problems.

Suppose the robot originally welded correctly but the welding position has now shifted by 2 mm. An operator may simply move all robot welding points by 2 mm.

This might temporarily restore the welding position, but the actual problem may be caused by:

• Camera movement

• Calibration data changes

• Fixture movement

• Coordinate transformation problems

• Robot end-effector position changes

If the root cause is not corrected, modifying the robot program can create an even larger mismatch between the vision system and robot coordinate system.

A better approach is:

Identify the source of the deviation first, then determine whether the vision system, fixture, coordinate calibration, or robot program needs adjustment.

9. What Should Be Done After Temporarily Restoring Production?

Even if temporary calibration restores the welding position, it is not recommended to immediately return to full-scale production.

A gradual verification process is better:

Single-part test → Continuous test → Sampling inspection → Normal production

Check:

• Welding position accuracy

• Weld seam tracking stability

• Weld appearance

• Weld deviation

• Workpiece positioning consistency

• Vision recognition stability during continuous operation

If the positioning remains stable during continuous testing, production can gradually return to normal.

10. When Should You Avoid Performing Temporary Calibration Yourself?

Not every vision problem should be handled by production operators.

Professional technical support is recommended when:

• The camera cannot connect

• The vision controller reports a hardware fault

• Calibration data has been lost

• The camera or lens has suffered a collision

• The robot has collided

• The laser welding head has moved

• Robot zero-point or mechanical parameters are abnormal

• Vision recognition continues to drift significantly

• The machine reports a safety alarm

• The impact of parameter changes cannot be confirmed

In particular, problems involving the robot, laser source, safety circuit, or critical calibration data should not be handled through trial-and-error adjustments simply to restart production.

11. How Can Vision System Failures Be Reduced?

Preventive maintenance is more effective than troubleshooting after a failure occurs.

Clean the Vision System Regularly

Establish a cleaning and inspection schedule for lenses and protective glass according to the production environment.

Secure the Camera Mounting Structure

Regularly inspect camera brackets and fixing screws to reduce position changes caused by vibration.

Back Up Calibration Data

Back up validated vision programs, calibration parameters, and robot programs.

Manage Operator Access

Restrict unauthorized changes to critical vision parameters and robot programs.

Perform Regular Accuracy Verification

Use a standard workpiece or calibration target to periodically verify the relationship between visual recognition and the actual robot position.

Maintain Equipment Records

Record vision faults, parameter changes, calibration activities, and maintenance work to make future troubleshooting easier.

12. What Should You Consider When Selecting a Robotic Laser Welding Machine?

For robotic laser welding applications involving vision positioning, weld seam recognition, or complex welding paths, the vision system should not be treated as an independent camera.

It needs to work together with the robot, laser welding head, control system, workholding fixture, and welding process.

When selecting a robotic laser welding machine, manufacturers should consider:

• Vision positioning method

• Recognition accuracy

• Calibration method

• Coordinate transformation

• Software operation

• Alarm functions

• Data backup

• Technical support

• Integration with the welding process

For customized automation projects, actual workpiece testing is particularly important before finalizing the equipment configuration.

PDKJ Robotic Laser Welding Solutions: Matching Vision and Welding Systems to Your Application

PDKJ is a professional welding machine manufacturer providing robotic laser welding machines and automated welding solutions.

Based on the workpiece structure, welding path, production cycle, and automation requirements, PDKJ can help evaluate suitable robotic laser welding configurations and vision positioning solutions.

Before purchasing equipment, customers can provide workpiece photos, drawings, or actual samples. PDKJ provides free welding process evaluation and sample testing to verify welding performance and equipment compatibility before finalizing the solution.

By evaluating the actual workpiece first and selecting the appropriate robot, laser welding system, vision system, and automation configuration, manufacturers can reduce equipment selection risks and improve the stability of robotic laser welding production.

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If you have welding machine requirements, please contact Ms. Zhao

E-Mail: pdkj@gd-pw.com

Phone: +86-13631765713