In an article recently published in the journal Applied Sciences, researchers proposed a hybrid fuzzy proportional-integral-derivative (PID) controller for quadcopter drones used in agriculture ...

It’s got the usual trappings of a drone ... test stand to work the problem through, and eventually rewrote LibrePilot to deal with the unique forces on the craft and tuned the PID loops accordingly.

In the old days, building a quadcopter or drone required a lot of hacking together ... it needs to make as well as making use of a PID control system to make its movements as smooth as possible.