Machine Vision
Incorporation of machine vision can be a very cost effective and robust method to any application, be it, reliability testing, manufacturing, or consumer applications. Using a webcam, here I was able to find the centroids of the two items using a filter to filter out any extraneous objects.
Top Left: Live image where the contours and centroids are applied.
Top Right: Canny edge detection - using a few built in methods to the OpenCV platform on Python, Canny edge detection has been known to be the most robust method if finding edges.
Bottom Left and Right: Threshold images compared for different values to see which produces the most effective contrast.