Path Followed Robot: Step-by-Step Complete Guide from Beginner to Advanced

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Path Followed Robot: Step-by-Step Complete Guide from Beginner to Advanced

By Home Academy Project



Introduction

A Path Followed Robot, commonly known as a Line Following Robot, is an autonomous robot designed to detect and follow a predefined path such as a black line on a white surface or vice versa. This project is one of the most popular entry-level robotics projects and is widely used in engineering colleges, polytechnics, ITIs, and competitive robotics competitions.

Despite being simple at the beginner level, the same concept extends to industrial automation, AGVs (Automated Guided Vehicles), warehouse robots, and smart transportation systems.

This article explains every concept step by step, starting from basics and moving towards advanced control and optimization, making it ideal for students, hobbyists, and project developers.

What is a Path Followed Robot?

A Path Followed Robot is an autonomous mobile robot that senses a path using sensors and adjusts its movement using a control mechanism to remain on that path.

The path can be:

A straight or curved line

A track with turns and intersections
A colored path or reflective tape
A digital path mapped using sensors

Basic Working Principle

The robot works on a simple Sense – Decide – Act principle.

  1. Sense: Sensors detect the path.

  2. Decide: A controller processes sensor data.

  3. Act: Motors adjust direction and speed.

Main Components of a Path Followed Robot

1. Power Supply

Provides energy to the robot.

Batteries (9V, AA, Li-ion, Li-Po)

Voltage regulators (5V, 12V)

2. Sensors (Most Important Part)

Sensors detect the path.

Commonly Used Sensors:

IR (Infrared) Sensors

Reflective Optical Sensors
Color Sensors (Advanced)
Camera (Very Advanced)

IR Sensor Working Concept

Black surface absorbs IR → Low reflection

White surface reflects IR → High reflection

3. Controller Unit

The brain of the robot.

Beginner Level

No microcontroller (Comparator-based logic)

Intermediate Level

Arduino UNO / Nano

ATmega microcontrollers

Advanced Level

Raspberry Pi

ESP32
ARM Controllers

4. Motor Driver

Motors cannot be connected directly to controllers.

Common Motor Drivers:

L293D

L298N
TB6612FNG

Motor driver:

Controls direction

Controls speed
Protects controller

5. DC Motors and Wheels

DC geared motors for torque

Differential drive (Left & Right wheels)
Castor wheel for balance

Beginner Level Path Followed Robot (Without Coding)

Concept

Uses IR sensors + comparator circuit.

Working

If left sensor detects black → turn left

If right sensor detects black → turn right
If both detect white → move forward

Advantages

No programming required

Easy to understand
Low cost

Limitations

Not accurate on sharp curves

No speed control
Not adaptable

Intermediate Level Path Followed Robot (Using Arduino)

Required Components

Arduino UNO

2 or 3 IR Sensors
L298N Motor Driver
DC Motors
Battery

Sensor Arrangement

Left Sensor

Center Sensor
Right Sensor

This arrangement allows:

Straight movement

Smooth turns
Better accuracy

Logic Table (Basic Idea)

LeftCenterRightMovement
010Forward
100Turn Left
001Turn Right
000Stop / Search
111Junction

(1 = Black line detected, 0 = White surface)

Control Algorithm

  1. Read sensor values

  2. Compare values

  3. Decide direction

  4. Control motors

  5. Repeat continuously

Advantages

Programmable

Adjustable speed
Better performance

Advanced Level Path Followed Robot

At the advanced stage, the robot moves beyond simple logic.

PID Control System (Most Important Advanced Concept)

PID = Proportional + Integral + Derivative

It ensures:

Smooth movement

Less vibration
High speed with accuracy

Why PID?
Simple logic causes jerks and overshoot. PID continuously corrects error.

Error = Desired path – Actual position

PID Working Concept

P corrects current error

I corrects past error
D predicts future error

Used in:

Industrial robots

CNC machines
Drones
Self-driving vehicles

Multi-Sensor Array

5, 7, or 8 IR sensors

Detect curves, intersections, speed zones

Intersection Detection

Robot can:

Count junctions

Take predefined turns
Follow stored routes

Color-Based Path Following

Using color sensors:

Red, blue, green paths

Industrial sorting lines

Camera-Based Path Following (AI Level)

OpenCV

Image processing
Machine learning

Used in:

  • Autonomous cars

  • Warehouse AGVs

Applications of Path Followed Robots

Industrial material handling

Automated warehouses
Hospital medicine delivery
Airport baggage systems
Robotics competitions
Educational robotics labs

Common Problems and Solutions

Problem: Robot oscillates
Solution: Use PID control

Problem: Sensors give false readings
Solution: Proper calibration

Problem: Robot loses line
Solution: Add search algorithm

Skills You Learn from This Project

Embedded systems

Sensor interfacing
Motor control
Control systems
Robotics logic
Automation concepts

// Home Academy Project

// Path Followed (Line Following) Robot

// Arduino UNO + L298N + 3 IR Sensors


// IR sensor pins

#define leftSensor   A0

#define centerSensor A1

#define rightSensor  A2


// Motor driver pins

#define ENA 5

#define IN1 8

#define IN2 9

#define ENB 6

#define IN3 10

#define IN4 11


int motorSpeed = 150;   // Adjust speed (0–255)


void setup() {

  pinMode(leftSensor, INPUT);

  pinMode(centerSensor, INPUT);

  pinMode(rightSensor, INPUT);


  pinMode(ENA, OUTPUT);

  pinMode(IN1, OUTPUT);

  pinMode(IN2, OUTPUT);

  pinMode(ENB, OUTPUT);

  pinMode(IN3, OUTPUT);

  pinMode(IN4, OUTPUT);


  analogWrite(ENA, motorSpeed);

  analogWrite(ENB, motorSpeed);

}


void loop() {


  int leftValue   = digitalRead(leftSensor);

  int centerValue = digitalRead(centerSensor);

  int rightValue  = digitalRead(rightSensor);


  // Case 1: Move Forward

  if (leftValue == HIGH && centerValue == LOW && rightValue == HIGH) {

    moveForward();

  }


  // Case 2: Turn Left

  else if (leftValue == LOW && centerValue == HIGH && rightValue == HIGH) {

    turnLeft();

  }


  // Case 3: Turn Right

  else if (leftValue == HIGH && centerValue == HIGH && rightValue == LOW) {

    turnRight();

  }


  // Case 4: All sensors on black (junction)

  else if (leftValue == LOW && centerValue == LOW && rightValue == LOW) {

    moveForward();

  }


  // Case 5: No line detected

  else {

    stopRobot();

  }

}


// Motor control functions


void moveForward() {

  digitalWrite(IN1, HIGH);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, HIGH);

  digitalWrite(IN4, LOW);

}


void turnLeft() {

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, HIGH);

  digitalWrite(IN3, HIGH);

  digitalWrite(IN4, LOW);

}


void turnRight() {

  digitalWrite(IN1, HIGH);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, HIGH);

}


void stopRobot() {

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  digitalWrite(IN3, LOW);

  digitalWrite(IN4, LOW);

}

Perfect 👍
Below are clear, exam-ready block diagrams for a Path Followed (Line Following) Robot, explained from beginner to advanced level, exactly the way evaluators expect in a Home Academy Project.

1. Basic Block Diagram of Path Followed Robot

Power Supply
     │
     ▼
IR Sensors ───► Controller ───► Motor Driver ───► DC Motors
     ▲                                   │
     └──────────── Feedback ─────────────┘

Explanation

  • Power Supply provides energy to all blocks

  • IR Sensors detect the path (black/white line)

  • Controller processes sensor data and makes decisions

  • Motor Driver amplifies control signals

  • DC Motors move the robot

  • Feedback ensures continuous correction

2. Beginner-Level Block Diagram (Without Microcontroller)

Battery
   │
   ▼
IR Sensors ───► Comparator Circuit ───► Motor Driver ───► DC Motors

Explanation

  • IR sensors detect surface contrast

  • Comparator converts analog signal to logic HIGH/LOW

  • Motor driver directly controls motors

  • No programming involved

Used for:
Basic learning, low-cost projects, beginners

3. Intermediate-Level Block Diagram (Arduino-Based)

        ┌───────────────┐
        │   Power Unit  │
        └───────┬───────┘
                │
                ▼
        ┌────────────────┐
        │   IR Sensors   │
        └───────┬────────┘
                ▼
        ┌────────────────┐
        │   Arduino UNO  │
        │ (Decision Unit)│
        └───────┬────────┘
                ▼
        ┌────────────────┐
        │ Motor Driver   │
        │   (L298N)     │
        └───────┬────────┘
                ▼
        ┌────────────────┐
        │  DC Motors     │
        │ (Robot Motion) │
        └────────────────┘

Explanation

Sensors send digital signals to Arduino

Arduino executes control logic
Motor driver controls speed and direction
Robot follows the path smoothly

Used for:
College projects, robotics competitions, practical exams

4. Sensor Array Block Diagram (Improved Accuracy)

IR Sensor Array
(L1 L2 C R2 R1)
      │
      ▼
Microcontroller ───► Motor Driver ───► Motors

Explanation

  • Multiple sensors detect curves and intersections

  • Higher accuracy than 2–3 sensor systems

  • Essential for high-speed robots

5. Advanced Block Diagram with PID Control

              ┌──────────────────┐
              │   Desired Path   │
              └─────────┬────────┘
                        ▼
                Error Calculation
                        │
                        ▼
        ┌───────────────────────────┐
        │        PID Controller     │
        │ (P + I + D Algorithm)     │
        └─────────┬─────────────────┘
                  ▼
            Motor Speed Control
                  │
                  ▼
        Motor Driver ───► DC Motors
                  ▲
                  │
           Sensor Feedback Loop

Explanation

  • Robot calculates deviation from path

  • PID algorithm continuously corrects motion

  • Results in smooth, fast, and stable movement

Used in:
Industrial AGVs, smart robots, autonomous vehicles

6. Advanced AI-Based Block Diagram (Camera Vision)

Camera
   │
   ▼
Image Processing (OpenCV / AI)
   │
   ▼
High-Speed Controller
   │
   ▼
Motor Driver
   │
   ▼
Motors

Explanation

Camera captures path image
AI processes real-time visuals

  • Robot follows complex and dynamic paths

7. Flow of Operation (Control Logic)

Start
  │
Read Sensors
  │
Detect Path
  │
Calculate Error
  │
Decide Direction
  │
Control Motors
  │
Repeat Loop


“The block diagram shows how sensor inputs are processed by the controller to generate motor control signals for autonomous path tracking.”



Conclusion

A Path Followed Robot is not just a beginner project—it is the foundation of autonomous robotics. Starting from simple IR-based logic and advancing to PID-controlled intelligent systems, this project teaches core engineering concepts used in real-world automation.

For students, this project strengthens:

Conceptual clarity

Practical skills
Interview confidence
Competitive exam understanding

Home Academy Project
Learning Engineering with Clarity, Logic, and Real-World Application


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