Potentiometers, or variable resistors ... which a voltage controlled current source feeds the pot while an Arduino with a motor controller turns it through a stepper motor, and takes a voltage ...

The electric motor is the fundamental ... it lacks the precise positional control required for the task. Small servos from the modelling world will often use a potentiometer to sense where they ...

A rotary encoder is a wonderful digital alternative to the old analog potentiometers. Rotary encoders are useful ... rotary encoder hardware is up and running it’s time to tell your Arduino what to do ...