It looks like you are using the ObjectDetect module, right? This module is a bit tricky with simple objects, because it identifies objects by keypoints and associated descriptors. This works very well with complex, flat objects with non-repeated textures, for example a cereal box or a book cover. In those, the algorithm looks for points that have a very unique local appearance, and it matches those between the image you saved and the live image captured by JeVois.
If the object is too simple, then it may lack distinctive keypoints. You can try to adjust parameters hessian, goodpts, and distthresh (see http://jevois.org/moddoc/ObjectDetect/modinfo.html
) but that may not be enough.
For colored disks, you may want to check out
and modify the python code to look for disks instead of a u-shape.
Or this color-based algo:
or this for several colors: