With regards to what happens when the joystick returns to center - the turret simply stays at the last angle it was directed to go to. We use the magnitude (the R value coming out of the Labview rect => polar coversion vi) to add a deadzone to the joystick.
Seeing this thing in action the first time (in our room) dropped the jaws of many team members. I have to give all the kudos to the two Junior programmers and the two sophmore programmers who did it. The math is far easier than I thought it would be when we started.
The neatest part of it was when we put the robot on a turntable. You could push the joystick in a direction and release it. From then on, no matter how you turned the robot on the turntable, the turret always pointed in the same direction. I was amazed.
It allows anyone to walk up to our gunner station and have intuitive control. Push the joystick toward the target robot, and you're on target. We're going to let judges play with it to see if they're as startled by the performance as we were
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Al - we considered a pot - like a 10 turn. However, I was concerned about what would happen in the off-instance where the gunner reached the end of the turns in a critical situation and had to spin it around the other way. I like trying to simplify and plan for every eventuality, and that created a problem I didn't want our gunner to have to deal with.