PC-Eyebot - Tutorial – Inspection of Bottle Cap Placement Vision... · PC Eyebot – Inspection...

Sightech Vision Systems, Inc.

PC Eyebot

Tutorial – Inspection of Bottle Cap Placement

Published 2005

Sightech Vision Systems, Inc. 6580 Via del Oro San Jose, CA 95126 Tel: 408.282.3770 Fax: 408.413-2600 Email: [email protected]: www.Sightech.com

mailto:[email protected]

http://www.sightech.com/

PC Eyebot – Inspection of Bottle Cap Placement

- page 2 - ©Sightech Vision Systems, Inc.

The purpose of this machine vision inspection: Often machine vision inspection is needed to make sure the caps are secured properly on bottles of different types. Because of the wide variety of bottle types, colors, and shapes encountered, our self-learning machine vision is well suited to inspection tasks such as this. The user will especially appreciate that no programming is required to initially setup or later add new product types.

The setup: a) We will inspect 2 sizes of bottles with two inspection Areas. The bottles will be

intermixed on the conveyor, so our machine vision system must be able to inspect either one without knowing, in advance, which one it is.

b) Bottles with caps that can be cocked, loose or missing. c) Backlight placed behind the bottle being inspected – there is no front lighting. The

backlight must be DC or high-frequency (25KHz or more). d) Bottling conveyor that moves bottles no faster than 400 FPM (feet per minute) and not

more rapidly than 14 PPS (parts per second). e) Camera which views from the front – we use a Sony DFW-VL500 1394 progressive scan

640x480 VGA resolution camera for this application.

Strategy – we will: a) Setup lighting to create a black silhouette of the bottle against a white background. This

lighting setup is very effective and common – it provides a clear noise-free image, provides the detail needed to check bottle cap placement, and minimizes effects of stray light from the surroundings.

b) Depending on the speed of movement of the bottles, set camera shutter speed sufficiently fast to “freeze motion”. For instance, if the bottles are moving at 100 FPM, a shutter speed of 1/1000 sec should suffice if a 1.4 f-stop lens is used. The brightness of the back lighting is important since the brighter it is, the faster the possible shutter speed setting that can be used. Also, a 1.2 f-stop lens would allow increasing the shutter speed to 1/2000.

c) Define 2 machine vision-processing Area’s – one for each size of bottle. Each Area will be centered on the corresponding bottle’s cap area. The will be both trained, and we will see that we can perform intelligent visual inspection on both sizes at the same time.

d) Use Video⇒Transform⇒Intensity for creating a binary (BW) image that will be used for processing by the self-learning machine vision engine. We will adjust the Video⇒Threshold⇒75 from ⇒50 to minimize imaging light reflections from the sholder of the bottles.

e) Select Feature⇒Type⇒Square because it provides a good general-purpose shape learning.

f) Select Feature⇒Size⇒Medium to make the feature’s size large enough to engulf the shapes around the area of the bottle’s neck. It is important that we learn these bottle neck-related shapes so we can properly judge cap placement.

www.sightech.com



g) Set Decision⇒Sensitivity⇒20, Decision⇒Region⇒10, Decision⇒Margin⇒0, Decision⇒Speed⇒Fast. The low Region setting sensitizes the vision system to small changes in bottle cap placement. The low Sensitivity setting causes FAIL to occur even when a small change in bottle cap placement is detected. Margin is set to 0 because, in this case, we are not interested in separating out marginal bottle cap placement defects. Starting PC-Eyebot.

www.sightech.com



Select VIEW Mode – Choose Image Video Transform and Self Learning Feature Settings:

The above example show the Video – Threshold ⇒ Intensity setting is too low (50) for this application – we are seeing front edge reflection from ambient light. Below, is a better setting for Video ⇒ Threshold.

www.sightech.com



Select Self Learning Feature Size to best fit Application:

When in VIEW mode, the pink rectangle in center of the Area depicts the size of the learning Feature. As you can see above, the largest one on the right is best sized to detect defects around the cap-bottle mating area. This Feature Size is specified as Large.

www.sightech.com



Define two Areas – One for each size of bottle:

a) Use Edit Areas to position 1st Area to larger bottle neck:

b) Use Edit Areas again to add an addition Area positioned to the neck of the smaller bottle.

www.sightech.com



Fine Tune the Areas on the main Image display:

a) Make settings for each Area in the main image window. This is accomplished by single clicking on each of the Areas and by using the console to modify the settings as you wish. This picture is before the changes:

b) This picture shows both Areas executing in VIEW mode after adjustments have been made to both Areas. Since All Areas is selected, many of the Area settings are grayed out. Later, we will see that selecting an Area enables all of the setting displays corresponding to that Area. (Reminder: The pink rectangles show the size of the learning features.)

www.sightech.com



c) We select the top Area, and you can see all the settings displayed for that Area. Note: You can also select Areas by using the drop-down box in the upper left side of the console. At this time, the settings for the selected Area can be adjusted further.

www.sightech.com



Training the Vision System with OK product: a) Make sure All Areas is selected. b) Initialize training memory by selecting ERASE mode:

c) Initiate training by selecting LEARN mode:

d) Note the orange “Hits” that indicate learning activity. More are present at the onset of learning and appear less and less as training progresses. If any single Area is selected, the Learning Rate can be observed. This is a value between 0…100 and approaches 0 as the selected Area becomes fully trained.

www.sightech.com



Inspecting product with defects: a) Making sure All Areas are selected, select INSPECT mode:

b) Supply bottles on conveyor that have defects. Note the bright pink marked areas near some of the bottles – this signifies defects.

www.sightech.com



Conclusion – we have demonstrated the following: a) Setup of the vision system for Cap Inspection was straightforward. b) Training on the bottles with correct caps was fast and effective c) Our vision system was trained on 2 sizes of bottles at once. These bottle sizes were

mixed on the conveyor. Multiple Areas were demonstrated and operated in parallel. d) Inspection was effective – misplaced caps were easily detected. 2 sizes of bottles were

mixed on the conveyor, and both were effectively inspected.

www.sightech.com

PC-Eyebot - Tutorial – Inspection of Bottle Cap Placement Vision... · PC Eyebot – Inspection...

Documents

Transcript of PC-Eyebot - Tutorial – Inspection of Bottle Cap Placement Vision... · PC Eyebot – Inspection...