The setup has to be non-intrusive.
Right now, my idea is to put the prop on the motor and use maybe a proximity sensor along with arduino interrupts to determine velocity vs. time.
Motor speed is around 30K RPM. This is a small brushless DC motor for a drone (aka: quadcopter). FYI, I can hold all 4 motors in my hand.
So..putting a magnet on a shaft would be impossible.
I want to develop a transfer function for the motor/prop and then model using laplace transform to determine PID coeffiecients.
Any ideas on this will be appreciated.