Tuning PID Constants Over a Range

[wireties]

Don't forget that you are tuning an electro-mechanical system.

For example if it is too hard to (begin) a turn then tuning the servo, by any means, is very difficult. This past year things like proper inflation of the pneumatic tires made all the difference (we were running Austin's state-space code).

An arm-like mechanism that takes much more power to move up than down is also very difficult to tune - so balance the motion against gravity with a gas shock or surgical tubing.

Set yourself up for success with good mechanical design, software can only do so much!