I made a tutorial video that shows how to set up TensorFlow's Object Detection API on the Raspberry Pi. TensorFlow is Google's open-source machine learning framework that I've been using for object detection applications, like using a Picamera to detect when a rabbit is in my garden eating my precious vegetables.
If you're looking for a fun object detection project to do with your Pi, check out my video!
https://www.youtube.com/watch?v=npZ-8Nj1YwY