They’ve taken the field-oriented control algorithm and encapsulated it into a compact Arduino ... measure both motor current (think: shunt resistor) and rotor position (think: encoder).

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 ...

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 ...