Build yours at home
Human line follower
What we're doing
Be the robot. One person walks blindfolded along a tape line. Two others are its sensors and call out when a foot touches the line. Rule cards say which way to turn.
About 15 minutes. 3 people.
Goes with these lessons
Get these parts
- Masking tape (household)
- A blindfold or sleep mask (household)
- Cards A, written on paper: LINE LEFT → TURN LEFT, LINE RIGHT → TURN RIGHT, BOTH SEE LIGHT → GO STRAIGHT (household)
- Cards B: LINE LEFT → TURN RIGHT, LINE RIGHT → TURN LEFT, BOTH SEE LIGHT → GO STRAIGHT (household)
Keep it safe
A grown-up spots the blindfolded walker at all times and clears the floor first. Walk slowly, arms out. No batteries or tools needed.
Steps
- 1Which sensor sees the line?
Tape a long line on a clear floor, with a few gentle curves.
- 2
Pick the robot and its two sensor helpers. The robot puts on the blindfold and stands with the tape between its feet. The left sensor watches the left foot and the right sensor watches the right foot. A sensor calls 'dark!' when its foot touches the tape. 'Light' means the floor.
- 3Follow the line
Lay out cards A. The robot takes small steps and follows the cards: left sensor calls, turn left; right sensor calls, turn right; nobody calls, go straight.
- 4
Swap to cards B and walk again. The robot turns away from the line and gets lost, like the on-screen robot with cards B.
- 5
Take off the blindfold. Which sensor called when the robot drifted?
Talk while you build
- Which sensor calls dark when the robot drifts?
- What changes when we swap the rule cards?
Spot it at home
- Robot vacuums have little light sensors under the front that look down to stop them falling down stairs.
Why would a robot need two line sensors, not one?
- Some warehouse and hospital robots follow lines or tape on the floor. We follow a path the same way, by noticing when we drift.
What do you do when you drift off a path?