Lesson 3 of 6 · 9 min · +100 XP
How robots sense the world
- Recognise the 6 sensors every roboticist knows
- Pick the right sensor for a real-world task
Before a robot can do anything, it needs to know where it is and what's around it. That's harder than it sounds.
The 6 sensors a robotics engineer can't avoid
Ultrasonic (HC-SR04 — ₹60) — sends a sound pulse, measures the echo. Tells you distance. Cheap and reliable.
Infrared (IR) — ₹40 — detects light reflections. Line followers and proximity sensing.
Camera — ₹350+ — the most powerful and most complex sensor. A whole world of computer vision lives here.
IMU (MPU-6050 — ₹180) — accelerometer + gyroscope. Tells the robot which way is up, how fast it's accelerating, how it's rotating.
Encoder — ₹250 — counts wheel rotations. Without one, your robot doesn't know how far it has moved.
LiDAR (RPLIDAR A1 — ₹6,500) — laser-based 3D mapping. The reason self-driving cars work.
Sensor fusion
No single sensor is enough. A camera fails in the dark. An ultrasonic sensor can't see colour. Real robots combine 3–10 sensors at once and merge the data — this is called sensor fusion.
This is why the same robot can navigate a sunny street, a dark warehouse, and a foggy morning.
A line-following robot needs to detect a black line on a white floor. What's the simplest, cheapest sensor for the job?