Build an Edge Avoiding Robot Using a Single IR Sensor

Introduction

An edge avoiding robot is a robot that can move on a raised surface such as a table while preventing itself from falling off the edge.

The robot continuously monitors the surface beneath it using an infrared (IR) sensor. When it detects that the surface is ending, it automatically changes direction and continues moving safely.

This project is designed for beginners and demonstrates how sensors can be used to make autonomous decisions in robots.

Building the robot

Step 1: Prepare the testing surface

Choose a clean table with a clearly visible edge.

The table should provide enough space for the robot to move freely while testing its edge detection capability.

Step 2: Build the robot chassis

Assemble the robot chassis using:

• Two geared motors
• Two wheels
• One caster wheel
• Chassis plate

Ensure the robot moves smoothly before mounting the electronics.

Step 3: Connect the circuit

Assemble the circuit using the modules listed above & attach it securely on the robot chassis.

Position the IR sensor near the front edge of the robot and facing downward toward the table surface.

Tip: Using an icecream stick (popsicle stick) will help IR Element detect the line well.

Step 4: Tune the IR Sensor

Proper tuning is important for reliable edge detection.

Rotate the potentiometer on the IR sensor and set it approximately to the middle position.

Test the sensor by moving it over the table surface and then beyond the edge.

Step 5: Test the robot

Place the robot on the table and switch on the power.

Observe the behavior:

• On the table surface, the robot moves forward.
• Near the edge, the sensor loses the surface signal.
• One motor stops.
• The robot turns.
• Once the sensor detects the surface again, the robot resumes forward movement.

How It Works

Case 1: Sensor Detects the Table Surface

When the IR sensor detects the table surface:

• Motor X runs.
• Motor Y runs.
• The robot moves straight.

Case 2: Sensor Reaches the Edge

When the sensor no longer detects the table surface:

• Motor X continues running.
• Motor Y stops.

This causes the robot to rotate and change direction.

Case 3: Sensor Returns to the Surface

After turning, the sensor again detects the table.

• Motor Y starts running.
• The robot moves straight again.

Demonstration

The robot continuously alternates between moving straight and turning whenever it reaches an edge.

This allows it to travel around the table without falling.

Learning Outcomes

By completing this project, learners will understand:

• How IR sensors detect surfaces
• Basic autonomous robot behavior
• Sensor-based decision making
• Differential drive movement
• Real-world applications of edge detection

Applications

Edge detection is widely used in:

• Robotic vacuum cleaners
• Service robots
• Autonomous vehicles
• Industrial robots
• Safety and accident-prevention systems

Conclusion

The edge-avoiding robot demonstrates how a simple sensor can help a robot make decisions and navigate safely. Through this project, learners gain hands-on experience with sensors, motor control, and the basics of autonomous robotics.

It is an excellent project for students, makers, STEM clubs, classrooms, and robotics workshops.