Higher-end robots use navigation systems that follow a (mostly) predictable path through your home and are smart enough to make a map of the space as they work. They rarely miss patches and don’t spend much time re-cleaning areas that they’ve already visited. If their batteries run low before they can finish cleaning, they’re smart enough to drive right back to their dock, recharge for a few hours, and pick up where they left off. Some of them even let you pick specific rooms to clean or draw invisible “no go” zones on their maps, using a smartphone app.

These bots can use a handful of different technologies to make their maps, but the most common options are ceiling-facing cameras, laser rangefinders, or gyroscopes. Robot nerds like to argue about which tech works better, but it really depends on how well it’s implemented. We’ve used great LiDAR robots and great camera robots—and terrible versions of each, too. Gyro bots haven’t been around as long as the other types, but they do tend to cost less. The early models weren’t overly compelling, but the technology can work pretty well, and we’ll try to keep an open mind as it matures. The relative strengths and weaknesses of each method will play differently depending on your home’s layout and how you use the robot.

Even though they cost extra and use cooler tech, mapping robots don’t always work better than cheaper bump-and-run robots. They can get stuck in the same traps. Even with the best models, their complex nav systems can get confused and glitchy when they find themselves in an unexpected situation, like when they encounter an especially cluttered area. And in our experience, because they’re supposed to be so smart, it feels extra-frustrating when they don’t work well.

Cleaning performance matters, but not as much as you think

We’ve found that as long as a robot has a brush roll and a side brush, it’ll pick up crumbs, tufts of pet hair, and other common debris from bare floors and low-pile rugs. That’s enough to keep most homes tidy, and most owners seem happy with it.