🎒 What you need

the shared phone with a free browser robot simulator or block-and-Python robot environment
your control loop diagram from module 1
paper for logging results

✋ Do this

Set up a line-following task. Before writing anything, name your sensor, your decision and your action out loud.
Write the crudest possible controller: if the sensor sees dark, turn one way; otherwise turn the other. Run it.
Watch it wobble violently down the line. That wobble is the signature of on-off control — point at it, it is important.
Log the time to complete the course. Then double the turn amount and log again. Then halve it. Three numbers, one table.
Add a straight-ahead zone: only turn if the sensor is strongly one way. The wobble should shrink. Log the time again.
Now break it on purpose: add a sharp corner it cannot handle, and write down exactly why it fails.

💡 Why it works

On-off control, also called bang-bang control, is the simplest thing that works and it is genuinely used where the wobble does not matter — a fridge thermostat, for instance. But on a moving robot it wastes energy and overshoots constantly. Feeling that limitation yourself is what makes the next module land.

🔥 Challenge

Beat your best lap time by changing only ONE number per run, logging every attempt. Bring your table to module 6 — you will need it.

📖 New words

bang-bang controla controller with only full-on and full-off outputs

overshootgoing past the target before correcting back

simulationa model of the real system you can test against safely

🕹️

Sim Runner

Tap when you have finished this module.