J
jeremy
12 minutes
Tuning a Drone PID Rate Loop
A drone flight controller runs a rate loop for each axis. It reads the gyro, which measures how fast the frame turns in degrees per second, and sets motor speeds to match the rate you ask for. An angle loop may sit on top of it. The rate loop is very fast, and the gyro is noisy because the motors and props shake the frame. D is needed to damp quick moves, but it boosts that noise, so it must be filtered. Learn the signs of each gain. Too much P gives a fast shake or buzz you can see and hear. Too much D sends noise to the motors, which come back hot, and that heat can burn them out. A slow wobble, or a drift back after a quick flip, often points to the I term. Other faults look the same. A loose part, a bent prop or a weak filter can also cause shake, so check the hardware before the gains. Tune one axis at a time and change one gain at a time. Fly short hops and touch the motors after each flight. Propwash is a wobble when the drone drops through its own air, and it is often a trade between D and filtering. Do bench tests with the props off, and fly away from people. After this Concept you can tell from a shake, a wobble or a hot motor which rate loop gain to move, and in which direction.