Dusty
THE INVENTION
A little robot that lives on the table, sweeps up crumbs, and stops itself right at the edge instead of driving off.
What it does, the experiment, the parts, and the plan to get it done.
Due Monday, November 16
1
What it does
A robot vacuum would drive right off a table. Dusty is built for that job.
Sweeps
A spinning brush at the front flicks crumbs up into a little tray, the same way a dustpan works.
Sees the edge
Two invisible infrared beams point down at the table. When the bounce stops coming back, the table is gone.
Stops in time
It backs up, spins a random amount, and drives off in a new direction. It has 62 mm to stop. Driving slowly, it only needs about 8.
2
The question I am answering
A robot alone is a cool thing. A robot plus a graph is a science project.
The question
How fast can a robot drive and still stop before it falls off the table?
Going faster means less time to react. That is true for elevators, for cars that brake by themselves, and for my robot.
What I change
Motor speed. Four settings, from slow to full power.
What I measure
How many millimeters it takes to stop, and how many times out of 20 it falls. The falls count is the proof it is safe.
What stays the same
Same table, same power bank, same sensor height, same running start.
My prediction
Stopping distance grows faster than speed. Slow, it needs about 8 mm. Full speed, about 38 mm. It has 62 mm, so it never falls, and the chart shows the speed where it finally would.
3
The sensor gets there first
The sensor sits 62 mm in front of the wheels. That head start is the whole trick.
By the time the wheels reach the edge, the robot has already stopped.
4
Parts to order
Check them off as they show up in the mail.
TotalAbout $150
Prices are rough. The parts list PDF has the real ones, plus a backup for every part.
5
Six weekends, then three spare
Every weekend ends with something that works. The spare weekends are on purpose.
Week of Sep 14Order the parts and print the bodyOrder everything at once. While the box is on the way, print the first three batches of body parts.Done when: Parts ordered, batches 1 to 3 printed
Sep 19-20Make it drivePrinted base, two motors, wheels, the caster, the power bank, micro:bit. No sensors and no brush yet. Just forward, backward, and spin.Done when: It drives across the kitchen floor
Sep 26-27Teach it about edgesMount the sensors out front, wire the whisker, write the code that stops and turns. Then put it on the table and find out.Done when: 20 tries, 20 stops, written down
Oct 3-4Make it cleanAdd the brush and the tray. Weigh out 5 grams of crushed cereal, run the robot, then weigh what ended up in the tray.Done when: A number for how much it caught
Oct 10-11Run the experimentFour speeds, 20 runs each, measuring how far it takes to stop and counting the falls. Then the spill race.Done when: A data table and two charts
Oct 17-18Fix and finishReprint any part that broke or wore out. Give Dusty a face on the LED screen.Done when: It passes every test again
Oct 24-25Build the display boardQuestion, prediction, method, graphs, photos, and Dusty on the table. Practice saying the whole thing out loud.Done when: I can explain it without notes
Oct 31-Nov 1Spare weekendHalloween. Left empty on purpose.
Nov 7-8Spare weekendFor whatever broke, or for redoing a test that came out messy.
Nov 14-15Last checkCharge the power bank, run the demo three times, pack it up carefully.
Mon Nov 16Turn it inRobot, display board, and the packet.Done when: It is handed in
6
Things that will probably go wrong
Written down now, so when they happen, they were planned for.
A dark table looks like a cliff
Black placemats swallow the light, so the robot thinks the table ended and refuses to move.
Fix: Press A to calibrate it on whatever table it is sitting on.
Shiny tables bounce light sideways
Glass is the worst case. The light hits it like a mirror and goes off at an angle instead of coming back.
Fix: Test on glass early and say honestly that it does not work there.
The brush throws crumbs on the sensors
One crumb sitting on a sensor blinds it completely.
Fix: Put the sensors in front of the brush, never behind it.
The battery runs out at the fair
The power bank keeps Dusty at full speed, then stops all at once. Its charge lights are hidden inside Dusty.
Fix: Charge it the night before. A full charge runs Dusty for hours.
7
Stuff I get to decide
The name: Dusty
Picked. It goes on the display board, on the LED face, and on the robot itself.
The face
25 LEDs on the front of the micro:bit. Eyes, a mood, a battery meter, whatever I want.
The brush
Pipe cleaners on a printed roller. Trim the length until the bristles just touch the table.
How it searches
Random bouncing on button A for the whole table. Spot Clean on button B sweeps a 1 foot square in front of Dusty, for a spill. Racing the two is my second experiment.