Arduino project · Motors and movement · Medium
Line Follower that Stops for Obstacles
The line follower stops if something comes closer than 20 cm in front.
What you will learn
- How to combine line following and safety
- Why the last step wins
- How delivery robots stop for people
How it works
The first three steps follow the line. The last step stops the car if the ultrasonic distance is under 20 cm. Use the distance slider to test it.
Try this next
- Beep while stopped.
- Wait 3 seconds then try to go around.
- Add LEDs for moving and stopped.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A robot following a road
The line sensors keep the robot on the road. In the stop version it halts when an obstacle appears.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Line sensors = the road edge
- Car = the robot driving