Tutorial

Project Comprehensive Overview

The Line Follower Robot with Obstacle Avoidance is a multi-modal autonomous vehicle that combines navigation and environmental awareness. It primarily follows a black line on a white surface but can proactively stop or detour when an obstacle blocks its path. This project is a perfect entry point into advanced robotics control algorithms.

Hardware Infrastructure

• Arduino UNO: Functions as the primary processor, managing inputs from multiple sensor arrays and outputting PWM signals to the motor drivers.
• IR Sensors (x2): These are the "line-tracking eyes." They emit infrared light and measure the reflection. Black surfaces absorb IR, while white surfaces reflect it, allowing the Arduino to determine the robot's position relative to the line.
• HC-SR04 Ultrasonic Sensor: Acts as a scanning radar. Mounted on a Servo Motor, it scans for clearing path if an object is detected directly in front.
• L293D Motor Driver Shield: This shield sits directly on the Arduino across all GPIOs, providing high-current control for the four BO Motors (Battery Operated motors). It allows the robot to drive all four wheels independently for high maneuverability.
• Lithium-Ion 3.7V 2000mAh Battery: Provides the substantial current required for the four-motor drive system.
• 3D Printed Chassis: A custom coral-themed casing that provides both structural support and aesthetic appeal.

Navigation Logic and Control Flow

The robot's behavior is governed by a hierarchical priority system:

1. Obstacle Detection (Highest Priority): The Arduino constantly reads the ultrasonic sensor. If an object is detected within a certain distance (e.g., 20cm), the robot stops immediately to avoid a collision.
2. Line Following Logic:
   • Centered: Both IR sensors are over the white surface; the robot drives forward.
   • Off-Course Left: The left IR sensor hits the black line; the Arduino slows the left motor and increases the right motor to steer back onto the line.
   • Off-Course Right: The right IR sensor hits the black line; the Arduino slows the right motor and increases the left motor to turn back.
3. Differential Steering: For tight turns, the motor driver can spin the wheels in opposite directions, allowing the robot to execute zero-radius turns.

Why This Project is Important

This build is an excellent introduction to Sensor Fusion and State Machines. It teaches builders how to handle conflicting sensor data and prioritize safety (obstacle avoidance) over objective completion (line following). The addition of the 3D-printed casing also introduces makers to the basics of mechanical design and prototyping.