When I originally got the idea for this, I searched google and found a paper written about the pressure way. They used a bag filled with water. My bag isn't water filled, so how would I get the pressure thing in there, cut the bag open?
Second, if you know of a system for sale, let me know.
Third, I was talking to a guy from a robotics forum and he might have a solution. The only problem is the connecting to a computer. Is there a way to have a usb send the data wirelessly to a computer without using a big box-like server, ie something I could put on the bag so there doesn't have to be a cable running from the bag to a computer?