After having taken a break on this model I am back and working on rigging it, a first for me. I have my arm rigged for instance and I can control it well, but a problem that I am running into is that I would like to have the shoulder plates move when the arm would come in contact with them. I would like to avoid anthing to computationally complex such as rigid bodies (I am under the impression that they take a long time to compute).

I've attached an image of what I mean. Right now the arm moves up and the should stays still, I would like that when the arm reaches the shoulder plates they start to move up with it as if being pushed. I tried set driven keys and that works well when rotating the arm in one axis at a time, but not when I rotate the arm in two axis directions at once.