Development of Line Follower and Ultrasonic NodeMCU ESP8266 Motor Shield

Abstract

This project details the design, implementation, and optimization of a low-cost, autonomous mobile robot that integrates dual functionalities: line-following and ultrasonic obstacle avoidance. The system utilizes a NodeMCU ESP8266 microcontroller as its central processing unit, interfaced with an L298N motor shield for precise bidirectional control of two DC gear motors. For navigation, an array of three TCRT5000 infrared reflectance sensors is employed to track a high-contrast black line on a white surface. Concurrently, an HC-SR04 ultrasonic sensor provides real-time obstacle detection to enable avoidance maneuvers. A primary challenge addressed is the optimization of TCRT5000 sensor performance, where empirical testing revealed that a critical mounting height of 10–12 mm is essential to prevent signal saturation and ensure reliable differential detection between the line and the background.