Line-Following Robot Car - Detailed Build Guide
A line-following robot car is a small autonomous vehicle capable of detecting and following a path
marked by a line, usually black on white or white on black. It uses infrared sensors to detect
contrast and adjusts its direction accordingly. This guide provides a step-by-step approach, from
hardware assembly to software coding and advanced features.
Applications:
- Automated guided vehicles (AGVs) in warehouses and factories.
- Campus or office delivery robots.
- Educational robotics competitions.
- Prototype for autonomous driving algorithms.
- STEM learning projects for students.
Materials Required:
- Arduino Uno or Nano (or ESP32 for wireless control)
- Infrared sensor array (3–5 sensors, e.g., TCRT5000 or QTR-8A)
- DC motors (x2) with wheels
- Motor driver module (L298N or L293D)
- Robot chassis kit (with caster wheel)
- Battery pack (Li-ion 18650 or AA) with holder
- Jumper wires and breadboard
- Electrical tape or zip ties for securing components
- Black tape or printed track for testing
Framework:
- Step 1: Assemble the robot chassis by mounting the DC motors, wheels, and caster wheel.
- Step 2: Attach the IR sensor array to the front of the chassis facing downwards.
- Step 3: Connect the IR sensor outputs to Arduino digital pins.
- Step 4: Wire the motors to the motor driver, and connect motor driver inputs to Arduino.
- Step 5: Connect the battery pack to the motor driver power input.
- Step 6: Write the basic Arduino code to read sensor values and control motor direction.
- Step 7: Test the robot on a simple track and adjust sensor thresholds for accuracy.
- Step 8: Fine-tune speed and turning logic using conditional statements.
- Step 9: Implement PID control for smoother and more responsive movement.
- Step 10: (Optional) Add obstacle detection with an ultrasonic sensor.
Action Plan:
Step Task Estimated Time
1 Order and gather all components 2 days
2 Assemble mechanical body 1 day
3 Connect electronics and wiring 1 day
4 Write basic line-following code 1 day
5 Test and tune basic functionality 2 days
6 Implement PID control 2 days
7 Add optional features like obstacle avoidance 2–4 days
Basic Arduino Code Outline:
1. Define sensor and motor pins. 2. In `setup()`, set pin modes and initialize serial communication.
3. In `loop()`, read sensor values. 4. Use if-else conditions to control motor direction: - Center
sensor active → move forward. - Left sensor active → turn left. - Right sensor active → turn right. 5.
Use delay or PWM speed control for smooth operation.
Advanced Feature Ideas:
- PID control for smoother path tracking.
- Bluetooth or Wi-Fi manual override.
- Speed regulation using wheel encoders.
- Multiple path detection and selection.
- Track mapping with basic odometry.
Helpful References:
- Arduino Line Following Basics: https://lastminuteengineers.com/line-follower-robot-arduino/
- Pololu QTR Sensor Guide: https://www.pololu.com/docs/0J19
- PID Control Tutorial:
https://www.robotshop.com/community/forum/t/line-follower-robot-pid-control/13071
- Motor Driver L298N Guide:
https://lastminuteengineers.com/l298n-dc-stepper-driver-arduino-tutorial/
