If you have always wanted your own personal R2-D2 of dust but couldn’t stomach the high price of early robotic vacuums, it’s time to take another look. Roomba, made by iRobot, was so dominant early on that it was fast becoming a generic term, sort of like “Hoover,” which is used as a verb in some parts of the world. However, by my count, at least a dozen companies now make robotic vacuums, including well-known brands such as Samsung, Sharp and Black & Decker, plus vacuum specialists such as Ecovacs, Neato and Bissell.

Here’s what I learned from interviewing a Consumer Reports expert, reading articles and reviews about the latest models and technology, and talking to people who own these dogged little appliances. The biggest takeaway: Don’t plan on replacing your traditional vacuum with a robotic one. Robotic vacuums have come a long way, but you’ll still need an upright or canister vacuum for deeper cleaning and for stairs.

Lower prices

Increased competition has provided more price points among robotic vacuums. “There’s a huge range,” said Haniya Rae, who participates in vacuum testing at the nonprofit Consumer Reports. Some models still cost $1,000, but you can also score a reasonably well-rated robot vac for as little as $180 — the Black & Decker HRV425BLP. Last year, when Consumer Reports tested 27 models, one-third of them cost $375 or less. Even iRobot makes a Roomba I saw online for just $318. Several of those less expensive models ranked in the CR top 10.

Higher functionality

At the same time robotic vacuum prices have come down, their functionality has gone up. Their “cliff sensors” have improved, so they almost never fall down the stairs anymore. Although robotic vacuums are typically round, some manufacturers have put a straight edge along one side or added side brushes that help them clean in corners. Most are now flexible enough to straddle area rugs and hard floors, though they sometimes get hung up on long carpet fringe. “The technology is great, and it gets better with each iteration of these things,” Rae said. “But there are still some glitches that need to be worked out.”

Where they're weak

Robotic vacuums did not perform nearly as well as traditional upright and canister vacuums in Consumer Reports’ tests of their deep-cleaning ability. A traditional vacuum picked up more than half of the sand and talc embedded in a carpet sample, whereas the robotic vacuum sucked up less than 20 percent. Some robotic vacuums’ infrared systems have difficulty navigating on dark floors. Check the manual before you buy. Plus, they still cost more than a well-performing canister or upright vacuum.

What they do best

So what are robotic vacuums good for? Light, automatic maintenance. “These are great at doing little jobs every day,” Rae explained. “They’re meant to reduce the amount of time you have to do other vacuuming. You set it and forget it.” You can program your robotic vacuum to run every day at a certain time. “Since it’s running every day, you don’t have the Goldfish from three days ago that you forgot to pick up,” said Rae. Many robot vacuums are WiFi-connected, so they can map and learn the rooms of your house and then find their way back to their dock when finished. (If you’re worried about privacy, these maps are very abstract.) Some are also smartphone-connected, so you can prompt them to vacuum while you’re away at work or before you come home from vacation.

Robotic vacuums work best for picking up loose dust and debris on hard floors or low-pile rugs. They can run on carpets, too, but a deep pile sometimes exhausts their battery power before they’re done. They can work well for staying on top of pet hair, as long as the fur is not overly long or plentiful.

Because they can’t climb stairs, robotic vacuums are most useful for one-story homes, although, now that prices are lower, some people are buying one for each floor of their house.

To give a robotic vacuum the best chance of doing a good job, you’ll want to have uncluttered rooms. One thing they do better than traditional vacuums: cleaning beneath furniture, ­because they can glide right under it. (Measure your furniture and compare to the height of different robotic vacuums when choosing.)

Top-rated models

Consumer Reports lists four vacuums as “best buys” for their combination of high functionality and low price. They are the Ecovacs Deebot M88 ($450), the iRobot Roomba 690 ($375) and 618 ($270), and the Eufy RoboVac 11. ($250). Note that I was able to find some of these models for less than the list prices cited by the magazine.

The Good Housekeeping Institute’s 2018 top pick for a robotic vacuum is the iRobot Roomba 560, listed for $300. And PC Magazine’s recent list of its favorite robot vacuums also includes five that cost less than $350.

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