Troubleshooting for Workpiece Detection
Teaching of Pickup Position
In order to realize precise pickups, the pickup position of the workpiece should be detected properly as a model origin. To compensate the constant pickup position gap in workpiece handling due to the gap between the pickup position and the model origin, following methods are effective.
- Perform a model teaching by overlaying the model origin of the Corr or Geom object on the teaching point and set the CameraX and CameraY as the pickup position.
- To set the center of balance as a pickup position, detect it as a model origin by the Blob object and set the CameraX and CameraY as the pickup position.
* CameraX: X coordinate of the detected workpiece position in the camera coordinate system
* CameraY: Y coordinate of the detected workpiece position in the camera coordinate system
KEY POINTS
For details on vision objects, refer to the following manual:
"Vision Guide 8.0 - Software- Vision Objects"
If the workpiece Cannot Be Detected in the Search Area
If the workpiece which is in the search area cannot be detected and an image processing error occurs, it can be improved by adjusting the vision properties. See the following points.
Adjust the camera's exposure time
Long exposure time affects the work detection since it may blur the image of the moving workpiece. Use the ExposureTime property to shorten the exposure time.
Adjust the shape score value
If the work detection rate is unstable, it may be improved by adjusting the Accept property of the vision object.
KEY POINTS
For details on the vision properties, refer to the following manual.
"Vision Guide 8.0 Properties and Results Reference"
If Work Detection Does Not Satisfy the Required Accuracy
If the work detection does not satisfy the required accuracy, it can be improved by adjusting the vision properties. See the following points.
Adjust the camera's exposure time
Long exposure time affects the work detection since it may blur the image of the moving workpiece. Use the ExposureTime property to shorten the exposure time.
Adjust the camera's field of view
Wide field of view increases the length of 1 pixel and decreases the detection accuracy. Check the XmmPerPixel and YmmPerPixel values.
KEY POINTS
Example: If approximately 0.5 mm of the image blur at the 100 mm/sec of the conveyor speed is acceptable, set the exposure time to 5 msec.
KEY POINTS
For details on the vision properties, refer to the following manual.
"Vision Guide 8.0 Properties and Results Reference"
Tips for the case if the image processing cannot be done in time
If the image processing cannot be done in time, it can be improved by adjusting the search area and the vision properties. See the following points.
Tips for the case if the image processing cannot be done in time
Adjust the search window of the object
A large search window increases time to execute the vision objects. Adjust the search window as small as possible by eliminating the area where workpieces do not come in.
Adjust the number of the objects to be detected
When you want to detect only one workpiece at a time, setting the NumberToFind property to “1” may reduce the execution time.
Adjust the range of the expected scale
If there is no great variability in size of the workpieces, set the ScaleEnable property to “False”. If there is a small variability, narrow the ranges of the ScaleFactorMax and the ScaleFactorMin properties as much as possible.
Adjust the range of the angled detection
If there is no great variability in angle among the workpieces, set the AngleEnable property to “False”. If there is a small variability, narrow the range of the AngleRange property as much as possible.
Adjust the timeout period
A process is aborted when the image processing time is considered to exceed the timeout period. If image processing times vary, both the detection rate and the execution time may be improved by shortening the Timeout property.
KEY POINTS
For details on the vision properties, refer to the following manual.
"Vision Guide 8.0 Properties and Results Reference"
When Using A Thick Workpiece
If the workpiece is thick, the camera’s FOV includes the lateral side of the workpiece as shown in the figure below. If the top face and the lateral side of the workpiece have similar color, those two faces may be detected as a single top face of the workpiece. Pay attention to this influence especially when using the thick workpieces.
Influence of detecting the lateral side of the workpiece
KEY POINTS
This influence can be decreased by increasing the work distance or replacing the lens with a one with a long focal distance and a narrow angle of view.