Challenge 1
Set the mat up to competition standard — flat, taped, level table, lighting as it will be on the day — then run once cold with no practice first, and record the score.
The mission 4 min
Competition conditions on the marine mat — and the first round where most of your navigation has no line under it.
Everything you need exists. Today finds out what four lessons of gyro work are worth when nobody may help, the clock is running, and the robot has to cross open water to get home.
No coaching during a round. Once it starts, nobody touches the robot or the computer. Anything a teacher would normally call out has to have been built into the placement ritual and the program beforehand.
The full ocean 5 min
Everything is available today: the four reefs at A, B, C and D, the lighthouse island at E, and the octopus at F — with HOME at the harbour dock to start and finish.
Your lesson 17 budget already said this does not all fit. Run the route you costed, not the route you wish you had time for. A team that improvises a fifth station mid-round usually loses the four it had.
Have your abandon plan to hand — the mission you said you would drop if behind, and the signal that tells you that you are. Today is when that plan is tested.
What the gyro actually bought 12 min
Before the first round, work out what you expect this block to have changed. Then find out whether you were right.
- Turns should be repeatable. Lesson 20 replaced guessing with measuring. The before-and-after table is in your journal.
- Open crossings should be possible at all. Before lesson 21 the robot drove them blind. That is the single biggest change on this mat.
- Recovery should be real. A knock used to end a mission. With heading hold it becomes a correction — you proved that with a finger in lesson 21.
Drift grows with time, and rounds are slow. This is the one that catches teams today. A run that stalls, retries or waits is accumulating heading error the whole time it is not moving. If your round goes badly and the navigation gets steadily worse rather than failing outright, that is what you are watching.
Build it — set the venue up 10 min
Same discipline as lesson 16, plus one addition that belongs to this block.
- Mat flat, edges taped. A ridge beats any follower.
- Lighting as it will be on the day, and re-run the colour calibration if it has changed.
- Battery charged. A tired battery turns slower, which shifts every number you tuned — including your turn correction.
- A level table. New for this block. A mat on a slope pulls the robot off heading continuously, and heading hold will fight it all round without ever winning.
- Timekeeper and scorer from another team.
Program it — freeze it 12 min
The program is finished. Today’s job is to stop changing it and make it survivable under pressure.
Check Calibrate Gyro is the first thing on the canvas, and that the placement ritual from lesson 23 is written where the person placing the robot can read it.
Check your re-zero points are still in the program and still land where the robot genuinely knows its heading. A re-zero that has drifted into open water during last lesson’s debugging is a quiet way to lose a round.
And confirm the program on the Brick is the one you mean to run. Teams lose whole rounds to yesterday’s version.
Tune it — two minutes, one change 9 min
Between rounds you get two minutes, which is one change and nothing more. Decide what it will be while you are watching the round fail, not afterwards.
On this mat the tempting change is a gain. Consider instead whether the honest fix is a re-zero point or a squaring stop — those remove error, where a gain only manages it.
Make the change, run again, record whether the score moved. If it did not, put it back: an unhelpful change kept out of stubbornness costs you the next round too.
Run it — the scored rounds 6 min
Round one is cold. No practice lap, no warm-up, no last adjustment. Place the robot by the ritual, calibrate, start, hands off. Score it.
Two minutes. One change. Round two. Score it.
During both, have somebody watch specifically for where the robot ends up versus where it is pointing. That distinction was lesson 23’s diagnostic and it is the most useful thing an observer can record.
The journal — closing Block 3 4 min
The last lesson of a block collects the block:
- both round scores, and the one change between them
- whether your abandon plan triggered, and whether it was the right call
- what the gyro bought — turn accuracy against lesson 14’s numbers, and whether the open crossing worked at all
- every place the robot ended up wrong, marked heading or position
- the leg that is still not good enough, named plainly
That last line is Block 4’s starting point. If a long straight still wanders, or the follower still cannot be trusted at speed, PID in lessons 28 and 29 is the answer — and lesson 30 puts basic, proportional and PID side by side over one leg. It needs today’s numbers to do that.