I think the idea is neat, and the execution impressive, but what I do wonder about is why you created the shield? There doesn't seem to be much need for the effort it took, considering everything else is hooked up point-to-point?
Was it just a learning experience on how to make a PCB (nothing wrong with that)?
Finally - was this a project meant to be installed somewhere (for a client or buyer)? Is it portable?
I can't imagine building something like this (large and likely costing a fair bit of money - wheelchair motors, even on ebay, aren't exactly a dime-a-dozen) for the heck of it on a whim; is there an ultimate purpose?
Or is it one of those kinds of projects where you hope someone will buy it just so you don't have to store it long-term (I'm sure someone will - heck, I bet my boss would love to own it)?