How does a robot vacuum work? Navigation, suction, mopping and the station

How does a robot vacuum find its way?

ECOVACS writes that a robot uses sensors such as cameras or LiDAR to map your home. With that map it plans an efficient route, instead of bumping into things at random and missing spots. There are three common kinds of navigation:

• Gyroscope or IMU: tracks which way and how far the robot drives and builds a simple map from that. ECOVACS says this is often seen on basic models and is less precise than lasers or cameras.
• LiDAR: a laser measures distances all around the robot.
• Camera (vSLAM, according to Dreame): the robot recognizes fixed landmarks such as door frames and furniture and works out where it is.

Dreame explains that LiDAR sends out laser pulses and measures how long they take to bounce back. From that the robot calculates distances and builds a floor plan. After one run it saves that map and reuses it on every later clean.

LiDAR or camera: what is the difference?

Dreame sets the two side by side in a comparison. The laser maps precisely, even in the dark, because it carries its own light. It scans at a single height, so it can miss small or low objects, and it cannot tell what an object is. Transparent and black surfaces are hard for a laser to read.

A camera recognizes what is on the floor and adjusts the cleaning to it. According to Dreame it needs some light and maps more slowly and less precisely than a laser. Many newer models therefore combine both: the laser for the floor plan, the camera for obstacles. That is often called obstacle recognition.

Robots also carry sensors on the underside. ECOVACS names cliff sensors that look down and make the robot stop and turn away at stairs and ledges.

How does it pick up dirt?

ECOVACS describes it as three parts that work together. Side brushes sweep dirt toward the middle, from corners and along edges. The main brush loosens dirt and lifts hair out of carpet and cracks. Suction then pulls everything into the bin.

On some models the suction adapts. ECOVACS says advanced robots can raise suction on carpet and lower it on hard floors. How far a model gets on a charge is on its own page.

How does a robot vacuum mop?

Not every model mops. ECOVACS writes that a model with a mop function picks up fine dust and dried stains that vacuuming alone leaves behind. Dreame lists a water tank and mop pads among the parts of such a robot. Some models lift the mop pads or adjust the water flow when they sense carpet.

On a model with a station, the station washes the mops. Dreame lists rotating brushes that scrub the pads, plus hot-air drying as part of such a station. A station differs per model, so check what the maker states for the model itself.

What does the station do?

The robot has a small dustbin. A station with an empty function sucks it out. Dreame writes that the robot parks over the station’s intake port and the dirt moves into a larger bin or bag in the station. That means you empty far less often yourself. How long that lasts depends on your home and the size of the bin.

Here are the three kinds of station and what they cost now:

On sale today by kind: charging dock only 2, self-emptying station 12, all-in-one station 78. The middle all-in-one model costs $799. More on what you get with each kind is in our guide on what to look for.

What happens during a clean?

ECOVACS describes the order in five steps:

• Mapping: the robot works out where it is and creates or updates the map.
• Route planning: it picks an efficient path and watches for obstacles and stairs on the way.
• Cleaning: brushes, suction and, if fitted, the mop do their work.
• Adjusting: some models raise suction or lift the mop when they see carpet.
• Back to the station: it recharges and, according to ECOVACS, may carry on where it stopped if the battery ran low.

Looking after a Roomba? Read how to clean a Roomba.

Which model fits that?

Which navigation and which station you need depends on your home. These are the best-ranked models on sale now:

On sale today: 92. Highest ranked: Roborock Qrevo Edge 3 Pro ($999 at Roborock (brand store)). To match the choice to your home, use the advisor.