The encoder is attached to the motor shaft and delivers signals that will indicate speed or position. Rotary encoders come in two basic flavors: incremental and absolute.

Hooked to an Arduino, the motor made a workable encoder, later improved by sending each phase through a comparator and using digital inputs rather than using the Nano’s ADCs.

This paper presents a DC motor speed controlling technique under varying load condition. The linear system model of separately excited DC motor with Torque-variation is designed using PID controller.