Worked with a Process Control Engineer to solve a feedback loop response problem for a muti-ton Automatic Guided Vehicle (computerized forklift for an automated warehouse system). They had too much lag time in the loop + the tuning values for the controller were less than useful for a hydraulic servo steering system (hydraulic needs different settings as the torque/force is near instantaneous vs servo motors have a different torque/force profile).
Fixed it by custom coding a microcontroller that had PI precision tunable values & a fast response time. Able to get the curve to achieve optimal damping.
They were using Forth computer language for the high level application. However they had a bug that was elusive. A small test warehouse, where they cut a groove in the concrete & placed wires excited at different frequencies, so the AGV could follow different groove paths with a "pickup head". This area was the testing grounds for this monster.
When the rare Forth code bug surfaced, the hydraulic drive motors went wild. You instantly knew it was going to drive itself unpredictably once you heard the whining oscillation sounds in the hydraulic pumps. The engineers would instantly jump up and run away so as not to get run over by it. Once, it blasted the 20ft high steel roller doors off of the warehouse - the steel doors missed crunching a brand new red corvette by 2 ft.
Imagine... Something going wrong during testing. :)
Just can’t trust that new fangled digital stuff.
A good old fashioned manual kill switch might have helped too.