[yoshibrock]

I was actually thinking about this a couple days ago, but I abandoned the idea because of complications. I'll let you know what I came up with though.
I was thinking something akin to a cello tuning peg, where the cable would be fed through a little hole in the middle of a peg, and then the peg would be turned with a motor. When the peg is turned, the cable wraps around it and applies tension to whatever is attached to the other side.
And then I encountered the problem of the quick release. Depending on the amount of tension you will encounter, you'll have to decide on what motor to use. You'll probably need something that is geared for torque rather then speed, like a window motor. Unfortunately, window motors cannot unwind quickly enough to have a "quick" release. I started to think about using some sort of "cocking" mechanism to hold the peg in place until the actuation was needed, but I got lazy. Maybe you can figure something out? Just an idea