National Instruments NI myRIO, Essentials Manual

Page: 52 / 163

46 CHAPTER 7. COIN CALIPER II
Functional Requirements: The Coin Caliper II will:
1. Accept an image of a single circular coin contained in a user-defined
region of interest (ROI),
2. Measure the coin’s diameter in both pixels and real-world units (millime-
ters),
3. Report the coin’s diameter in both pixels and in real-world units as well
as the current time and date as a nondestructive image overlay,
4. Display the analyzed image when show analyzed is pressed, otherwise
display the webcam image,
5. Recalculate the real-world units scaling factor based on a coin of known
diameter when
calibrate
is clicked,
6. Save the currently-displayed image to a USB flash drive when save image
is clicked or when the NI myRIO onboard button is pressed,
7. Define the image file name as a user-defined base name combined with
the image sequence number,
8. Display the number of images saved during the current session,
9. Illuminate the NI myRIO onboard LED 0 when a coin is present, and
10. Illuminate the NI myRIO onboard LEDs 1 to 3 when a coin’s measured
diameter exceeds a user-defined threshold entered on the front panel.
Figure 7.1 on the preceding page shows the front-panel of the Coin Caliper II
application.
Required Resources:
1. NI LabVIEW and NI Vision Assistant
2. NI myRIO with power supply and USB cable
3. USB webcam and tabletop camera copy stand
4. USB hub (Stratom X-HUB or equivalent)
5. USB flash drive
6. Black velvet paper background
7. Ruler with millimeter and centimeter marks
8. Several coins of various sizes