How does a robot vacuum work? Navigation, suction and bases explained
After testing more than 60 robot vacuums, we know which parts decide how clean your floor gets and which are marketing.
Sarah Miller
Ryan Mitchell, editor-in-chief
October 20, 2026
60+ robots tested since 2021
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In this article
Key takeaways
- The software matters as much as the motor: route planning decides how much floor a robot covers.
- Lidar robots map accurately, even in the dark. Camera robots are better at avoiding cables, socks and pet waste.
- The suction number on the box says little about pickup. Brush design and airflow matter more.
- A self-emptying base turns a daily chore into a monthly one.
- Robot mopping wipes dust and footprints; only spinning pads touch dried spills.
What’s inside a robot vacuum
A robot vacuum works like a small regular vacuum: a motor creates airflow, a brush loosens dirt, and a filter keeps dust in the bin. What makes it a robot is everything around that.
Measures the room and builds the map. The round bump on top of most robots is a spinning laser.
Infrared sensors underneath that stop the robot at the top of the stairs.
Sweeps dirt out of corners and along baseboards into the robot’s path.
Lifts dirt out of carpet and into the suction channel.
Hold the dirt until the base empties the robot.
Good for 1½ to 3 hours, and replaceable on most models.
One cleaning run, step by step
This is what a typical lidar robot with a self-emptying base does from the moment you press start.
- Finds itself
It spins its lidar and matches what it sees to the stored map, so it knows which room it’s in.
- Plans the route
The software splits the floor into rooms and picks an order.
- Cleans the edges
In each room it follows the walls first, with the side brush sweeping the corners.
- Fills the room in rows
Then it drives back and forth in overlapping lines, like mowing a lawn.
- Boosts on carpet
Sensors underneath detect carpet and raise suction automatically.
- Recharges if needed
On a low battery it returns to charge, then resumes where it stopped.
- Empties itself
Back on the base, a second motor sucks the bin empty in about ten seconds.
Suction, brushes and airflow
What lifts dirt is airflow: how much air moves through the brush opening, and how well the robot seals against the floor.
The brush does the other half of the work. On carpet it lifts the pile so sand comes loose; on hard floors it mostly sweeps.
Self-emptying bases: bagged or bagless?
Without a base, a robot’s bin holds one or two runs of dirt, and most owners stop emptying it within weeks. A base sucks the dirt out after each run and holds weeks of it.
Dust stays sealed when you empty it, which is better for allergies. Bags cost $20 to $60 a year.
No bags to buy and a clear bin, but a small dust cloud when you empty it.
Myths, checked
Across 38 robots, pickup barely changed above 3,000 Pa.
It handles daily upkeep, not stairs, sofas or deep carpet.
Camera robots recognized fake pet waste in 9 of 10 runs in our test.
None of the major brands charge for mapping or scheduling.
This article explains how the parts work. To see which robots do it best, start with our tests.
Terms explained
Frequently asked questions
How long does a robot take to clean a home?
Can a robot vacuum go up stairs?
Why does my robot clean worse than when it was new?
Sarah has tested vacuums, mops, air purifiers and dehumidifiers since 2017. Before joining BrasQ, she spent five years as a test coordinator at a national consumer advocacy group. She studied industrial design at Ohio State and lives in Columbus with her family and a long-haired cat.
- Checked and updated.
- First published.
- BrasQ robot vacuum test data, 2021–2026 (63 robots)
- IEC 62929: Cleaning robots for household use, methods for measuring performance
- Manufacturer manuals and spec sheets