Barcode inspect system

[DavidLee]

hello,

Being a beginner of the vision system design ,there are some question to ask experts.

1, Need to check barcode print quality using IMAQ , what camera and DAQ card should be choosed ?
2, The barcode tape will be wrapped around a reel , which is driven by a stepper motor joint with a planetary gear system, due
to the reel's radius will turn to bigger and bigger along with running,the tape moving speed will be changed . For keeping the tape moving speed fixed , have to use a method to monitor the reel's radius size change so that to regulate the motor's rotate speed , could advise me what way can be used to monitor the reel's radium change ?

3, Because motor running , there will exist mechanical vibration , which can affect the image
process , what method should be introduced to prevent the viberation ?

4, Can generate or process 2D barcode with IMAQ ?

David

[BB_Phil]

Hello David,

Most of the questions are actually answered in the LabVIEW Machine Vision Course that NI offers. There is actually an Online version of this course that was recently introduced that is shorter. Let's take a stab at these questions...

1. This is a pretty involved question. Things you must keep in mind are cost, resolution, working distance, field of view, etc. Here are some documents from the www.ni.com website that may help:

Image Acquisition Tutorial
How Do I Calculate my Camera Sensor Resolution and Lens Focal Length? KnowledgeBase

After you find out what camera you want to use, then you can select the corresponding IMAQ board needed.

2. There are different kinds of sensors out there that can measure distances that you can research further. Of course, since you are already using vision you can have another camera take images of the reel from the side and calculate the radius, which is easily done with the Vision functions. On the other hand it may be simpler to accelerate your motor slowly every time at a set pace. Also, typically on reels there is a hole or notch at every item (or this case barcode). You can use a light sensor there to trigger the camera to take an image at every item. This may be the best because your reel can go at any speed and the images will be acquired the same way each time.

3. I'm not sure how bad of a vibration you're talking about. The barcode reader included in Vision will find the barcode dependent on the ROI (region of interest). Typically your ROI can account for any small offset. If you're talking about a large offset, you can always use a coordinate system to "reposition" your ROI's, using an edge or a pattern as a reference.

4. The latest version of the Vision software (7.1) does include 2D barcode support. Specifically, the Vision software supports PDF417 and Data Matrix (square or rectangular grid).

If you need more specifics or help on these issues, the Vision software does come with some good examples that demonstrate the different features. Also please consider the Online LabVIEW Machine Vision course to get a good grasp of all of these subjects and more.

Take Care,
BBP

[DavidLee]

Thank you BB.