This document discusses implementing a DC motor as a servomotor using an Arduino microcontroller and optical rotary encoder. It describes the components used - a DC motor, optical rotary encoder, motor driver, and Arduino. An optical rotary encoder detects rotational position using a light source, sensor, and encoded disk. A motor driver interfaces between the motor and microcontroller, providing sufficient power. Together these allow building an accurate, high-torque servomotor at lower cost than commercial servomotors.