This project presents the design and implementation of an autonomous Line Following Robot (LFR) developed entirely using fundamental digital logic gates without employing any microcontroller. The robot detects and follows a predefined path using a five-sensor Infrared (IR) array, while all decision-making and motor control operations are performed through pure combinational logic constructed from AND, OR, and NOT gates.
The project demonstrates the practical application of Boolean algebra, Karnaugh map (K-map) minimization, and digital logic design in real-world robotic systems. It was completed as part of the Digital Electronics Laboratory (EEE-314) course at Bangladesh Army International University of Science and Technology (BAIUST).
- Design a line following robot using only fundamental logic gates
- Eliminate the use of microcontrollers and software-based control
- Apply Boolean algebra and Karnaugh map techniques for logic minimization
- Understand the hardware-level implementation of robotic control systems
- Demonstrate the educational value of pure digital electronics in robotics
The robot uses five IR sensors arranged horizontally to detect the position of the line. Each sensor outputs a digital signal (HIGH or LOW) depending on whether it detects the line.
- L1 – Leftmost sensor
- L0 – Left sensor
- C0 – Center sensor
- R0 – Right sensor
- R1 – Rightmost sensor
- ML0, ML1 → Left motor control
- MR0, MR1 → Right motor control
Each motor is controlled using a 2-bit control scheme that determines forward, reverse, or stop operations.
- Move Straight: Both motors ON
- Turn Left: Right motor ON, Left motor OFF
- Turn Right: Left motor ON, Right motor OFF
- Stop: Both motors OFF
The logic outputs are derived from a truth table, optimized using Karnaugh maps, and implemented using standard TTL logic ICs.
- Infrared (IR) Sensors (5×)
- Logic Gate ICs: 7408 (AND), 7404 (NOT), 7432 (OR)
- L293D Motor Driver IC
- DC Geared Motors (2×)
- Buck Converter Module
- 7.4V Battery
- Chassis, Wheels, Breadboard, Jumper Wires
- Truth table created using five sensor inputs and four motor outputs
- Karnaugh map (K-map) minimization applied
- Implemented using:
- 14 AND gates
- 6 OR gates
- 4 NOT gates
- Built entirely with TTL logic ICs
- Components mounted on a foamboard chassis
- Two-layer design:
- Lower layer: Battery, buck converter, IR sensors
- Upper layer: Logic circuit on breadboard
- Optimized for a line width of 4.5–5 cm
- Handles straight paths, curves, zigzags, and intersections
- Successfully manages 90°, 45°, and 130° turns
- Reliable under controlled lighting conditions
Limitations:
- Line width below 4.5 cm is unreliable
- Sensitive to sensor alignment and noise
- No microcontroller required
- Transparent and deterministic logic
- Educational and cost-effective
- Higher hardware complexity
- Limited flexibility compared to programmable systems
- Digital electronics laboratories
- Educational robotics demonstrations
- Hardware-based autonomous navigation
- Course: Digital Electronics Laboratory (EEE-314)
- Department: Electrical and Electronic Engineering
- University: Bangladesh Army International University of Science and Technology (BAIUST)
- Submission Date: December 21, 2025
Md. Ashraful Islam
Assistant Professor, Department of EEE, BAIUST
- Jawad Nahin (ID: 1218017)
- Arzuman Ara (ID: 1218020)
- Khandker Mahazabin (ID: 1218028)
- Adnan Hossain Bhuiyan (ID: 1218031)
- M. Monsur Ahmed Evan (ID: 131014)
- M. Morris Mano, Digital Design
- L293D Motor Driver Datasheet
- https://github.com/Batushn/Logic-Gates-Line-Follower
This project is licensed under the MIT License.