[Andrew Blair]

Pneumatics are nice for two position action, but for variable control they don't seem to be very capable. I'm thinking however that variable control can be achieved by using two cylinders in parallel, such as with a bicep and tricep. however, when applying pressure to your "bicep" the second cylinder would be applying some back pressure, so that the cylinder would not contract all the way. I don't know if this is what you're using, but it makes sense that it could work.