Tons of design choices affect the way robot vacuums handle obstacles: the number and placement of bump sensors, whether the bot has any infrared or LiDAR or camera-based obstacle detection, the tuning of the drop sensors, the way the brushes spin, how the robot senses tangles or jams, the size of the wheels, the spring tension and pivot placement in the suspension, and the software that translates the sensory information into robot actions.

We can’t pinpoint one spec or feature that helps a robot navigate well—we just have to test the bots and see how they do. In our experience, price has nothing to do with a bot’s trap-escaping ability. Some of the most expensive models are the most likely to get stuck, and some of the cheapest ones are the most nimble.

Second, cover as much of your home as possible. If you have a smaller home, or don’t mind experimenting with barriers, then a cheaper robot with a semi-random navigation system can get the job done. If you have a bigger home, or simply would prefer something that looks smarter, moves predictably, and gives you more control, then you can spend more for a robot with a map-drawing nav system.

The simpler, semi-random system (we like to call it bump-and-run navigation) relies on luck and persistence—basically it bumps into something, spins in place to a semi-random angle, drives off, and repeats the process until the battery runs out (it’s actually a little more sophisticated, but you get the idea). This system looks dumb (and some people simply can’t stand to watch it), but we’ve found over and over again that it can cover as much or even more ground than the smarter map-drawing systems. iRobot CEO Colin Angle even told us that as of mid-2020, the bump-and-run Roomba 600 series models are still more likely to successfully complete an entire cleaning session than any of the map-drawing Roomba models.

Bump bots are most consistent in smaller spaces, with a practical limit of about 1,000 square feet. Even then, they might (semi-randomly) miss a patch of ground or even an entire room in any given session. But if you run the bot at least a few days per week, your floors should stay pretty tidy. In sprawling spaces, particularly if they have narrow doorways and long halls, bump bots just aren’t efficient—they’ll waste too much time wandering aimlessly and blindly fumbling around. You can try to shut a few doors, set up any barrier systems that might have come with the bot, experiment with different cleaning modes—or just upgrade to a robot with a smarter navigation system.