RESEARCH
Six things worth knowing before you build a table robot, with real sources to read for yourself.
Open the sources, read them, then explain what you learned in your own words. Never copy sentences.
Somebody already built the floor version
Robot vacuums clean floors. Nobody made the table version.
The robot vacuum you have seen is called a Roomba. It is made by iRobot, a company started in 1990 by three robot scientists from MIT. The first Roomba went on sale in September 2002 for about $199, which was cheap compared to other robot vacuums at the time.
Here is the funny part. Before it was called Roomba, the team called it DustPuppy.
- •Robot vacuums are for floors. Nobody made the table version, which is the gap your invention fills.
- •The first Roomba had a dirt tray you empty instead of a vacuum bag, the same idea as Dusty’s crumb tray.
- •iRobot gave the Roomba three separate safety systems just to keep it from falling down stairs. Falling is the number one danger for a driving robot.
Why can a floor robot not just be put on a table? What would have to be different?
How a robot sees a cliff with no eyes
Shine down, measure the bounce, no bounce means no table.
A cliff sensor is two tiny parts side by side. One is an infrared LED that shines invisible light straight down. The other is a detector that measures how much of that light bounces back.
On a table, the light bounces straight back up into the detector, so the reading is strong. At the edge there is nothing underneath but air and the floor four feet down. The light goes out and never comes back. That sudden drop is the robot’s word for "cliff."
- •Infrared is real light, just past the red end of the rainbow. Your eyes cannot see it, but a phone camera sometimes can.
- •A white or light surface bounces back roughly 60 to 80 percent of the infrared light. A black surface bounces back only about 10 to 20 percent.
- •These sensors work best a few millimeters from the surface. Too high up and the reading gets weak. That is why Dusty’s sensor arms slide up and down.
- •Sunlight has infrared in it, so bright sun can mess with the reading. Testing in the same light every time is a controlled variable.
Could you explain how a cliff sensor works to a friend without looking at this page? Try it out loud first.
The black tablecloth problem is real
Dark surfaces can look like a cliff to an infrared sensor.
A dark surface swallows most of the infrared light, so a cliff sensor looking at black carpet sees almost the same weak reading it would see looking off a stair. The robot thinks there is a cliff where there is only a dark rug.
This happens to real Roombas. Owners find their robot refuses to drive onto black or very dark carpets, because the cliff sensors keep false-triggering.
- •Your surface test, white paper against bare wood against a black placemat, tests a weakness that a big company still has not fully solved.
- •Your two fixes are the right ones: calibrate at startup on the actual surface, and add a whisker switch that does not care about color at all.
- •When a judge asks "what if the sensor is wrong," the answer is two different sensors that fail for different reasons. That is called redundancy.
What other surfaces at home might fool a sensor? How could you test that?
Dumb driving beats smart driving
The first Roomba had no map, and it worked.
The first Roomba drove in straight lines, bumped into something, turned a random direction, and drove again. It looked silly and it worked, because if you bounce around a room long enough you eventually cover all of it.
The expensive competitor at the time mapped the room with sound, like a bat, and cost about seven times more. The cheap random one sold a million a year.
- •Random bounce on button A is not the lazy option. It is what the real product shipped with.
- •Spot Clean on button B sweeps one small square in rows, like a lawn mower, which is what you want for a spill. Racing the two on the same spill is a second experiment.
- •Simple code that never crashes beats clever code that fails at the science fair.
Why might simple driving work better than clever driving? Which pattern do you think will clean a spill faster, and why?
What the brain actually is
A whole computer on a board smaller than a credit card.
The micro:bit is a whole computer on one small board, about 4 cm by 5 cm. It was made to teach kids to code, and it is Dusty’s brain.
- •25 red LEDs in a 5 by 5 grid. You can scroll sensor numbers across them and read them at the table with no laptop. That is why the micro:bit beat an Arduino for this project.
- •Button A and button B. Two cleaning patterns, one button each.
- •The edge connector, the gold stripes along the bottom, which is how the motor board and sensors connect.
- •A processor, the actual brain chip, which runs your blocks about as fast as you will ever need.
- •A power plug so it runs with no computer attached.
Which parts of the micro:bit will Dusty actually use, and what does each one do?
Why crumbs are worth cleaning up
Crumbs bring bugs, and wiping them onto the floor does not fix it.
Ants and cockroaches find food by scouting. When one scout finds crumbs it leaves a scent trail so the rest of the colony can follow. Pest control advice almost always starts the same way: wipe the table and sweep the floor right after eating.
What people actually do is brush the crumbs off the table with a hand. The crumbs land on the floor. The mess did not go away, it moved somewhere harder to reach.
- •Crumbs on a table attract pests.
- •Wiping with a hand moves them to the floor instead of removing them.
- •Dusty picks them up into a tray you dump in the trash, so the crumbs actually leave the house.
What happens to crumbs at your house after a meal? Where is a neutral source you could check this with, like a university extension page instead of a bug spray company?
Words to use out loud
Say the real word, then explain it in normal language.
How to cite a website
Pick three websites you actually read, and find each field yourself.
- Author
- Look near the top or bottom of the page. If no person is named, leave it blank.
- Title of article
- The big heading of the page you read, not the whole website.
- Publication date
- Often near the title or at the bottom. If there is none, write the date you read it.
- Website
- The name of the site or the group that runs it.
- URL
- The full address from the top of the browser, every character.
- •The form has two book slots, and websites do not count for those.
- •Search the library catalog for micro:bit, coding for kids, robotics for kids, and how robots work.
- •Each book needs author last and first name, title, copyright date, and publisher. The copyright date is on the back of the title page next to the little ©.
- •Do not write down a book you did not open. Read at least a few pages of each one.
Reading research does not count until it is on paper, in your own words, in cursive.