Comparing iRobot Scooba to the Mint Cleaner - Differences Between

Last week at the 2010 CES in Las Vegas, Evolution Robotics introduced a new product, the Mint Automatic Floor Cleaner. The press immediately labeled it as competition for the iRobot Scooba. Are they really that comparable? Let's look at the similarities and differences between the two.

The most obvious difference between the Scooba and the Mint is size and shape. While the Scooba is round, the Mint is square. iRobot claims that the round shape of its robots keeps them from getting stuck in corners and also helps them navigate. When you observe a Roomba or Scooba roaming around, you will notice that it turns in place, so one would expect that having corners would be a problem. For example, a square shape stuck in a corner will need to back out before turning. Looking at films of the Mint robot, it is clear that it needs to back up before turning when it meets a flat surface.

The dimensions of the iRobot Scooba are 5"H x 21.25"L x 17"D. A Scooba robot weighs 15.5 lbs. Being five inches high allows the robot to scoot under most furniture and overhangs. From past experience with iRobot products, I can vouch that they are small enough to fit between most chair legs. Things get a little dicey, however, in the dining room. In the dining room, a Scooba might have some trouble because there are a) The legs of the table and b) the legs of all the chairs. This can become enough of a maze that the robot won't be able to clean under large parts of it.

The stated dimensions of the Mint robot are simple "under 10 inches wide." From looking at pictures and movies of the Mint, it would appear that is probably 3 inches tall at most. This would definitely give it an advantage as far as getting under overhangs, low furniture, and also fitting into tight spaces.

The differences between the two floor cleaning robots really stands out, however, when you compare how they clean. The iRobot Scooba uses a four step process to prep, wash, scrub, and squeegee the floor. The first step removes loose dust and dirt from the surface, the wash step lays down a cleaning solution, then a cleaning brush scrubs the area, and finally, a specially designed squeegee lifts the cleaning solution and scrubbed up grime from the floor surface.

The Mint automatic floor cleaner has two main cleaning modes. First, it sweeps. To do this, you attach a cleaning cloth to the robot, and the robot runs around the room with it. For cleaning cloths you can use the microfiber cloths that come with the Mint, or the popular Swifter or cloths like it. These pick up dirt like a champ. The second cleaning mode is with a wet cloth. When cleaning with a wet cloth, the robot uses a scrubbing motion. It drives forward and back and side to side.

As you can probably see, these two robots are extremely different when it comes to how they clean. The Mint relies more on the ability of the cleaning cloth and scrubbing motion. The iRobot Scooba is much more active about how it cleans. Of course, the Mint requires less fuss. With the Scooba, you have to refill the cleaning solution from time to time, and you also need to empty the dust bin. With the Evolution Robotics Mint, all that is needed is a change of the cleaning pad.

While we don't yet have a great picture of the bottom of the Mint Automatic Cleaner, we do have ones of the iRobot Scooba. Here are the more obvious differences.

First, the Scooba has two drive wheels plus a third supporting wheel at the front. The cleaning parts are off-center to the right and are placed so that the robot can clean right up against any wall or surface it may need to. One classic complaint about Scoobas is that they don't get into corners. As you can see from the bottom, this would be impossible.

The Mint Cleaner has two wheels and the cleaning cloth holder. The cloth holder is wider that the rest of the robot and rectangular so it can get into corners and also clean right up to walls.

Another way the Scooba and Mint differ is in how they navigate a room. While both of them come with technology to detect cliffs and drop-offs, the iRobot device uses behavioral navigation while the Mint comes with technology to map the room it is cleaning.

Roombas and the Scooba use behavioral navigation to clean floors. They use a combination of wall-following, circling, spiraling, and turning to cover an entire floor. This ends up being kind of random, and the iRobot states that the Scooba actually ends up going over each part of a floor an average of five times. One consequence of this is that the robot ends up being less efficient and cleans less area with its battery life. At the same time, however, the Scooba is still capable of cleaning quite a large area before needing a charge. (A Scooba with a fully charged APS battery can clean approximately 500 square feet. One tank of cleaning solution washes 250 square feet.)

The Mint robot uses Evolution Robotics' NorthStar navigation technology. I might not be understanding it completely, but from what I can gather, you place the NorthStar module (a small box with a light on a corner) on a table in the room you want cleaned. The box maps the room and projects a beam on the ceiling which the Mint cleaner follows around the room. The mint cleans in an orderly fashion, moving back and forth across the room until it has covered the entire floor. (Evolution Robotics has specified that a fully charged Mint can run for 3 hours.)

Scoobas can use Virtual Walls. Virtual Walls are used to keep the robot out of areas or can be used to keep the robot in one room. There doesn't seem to be anything like that with the Mint, or maybe it is still under development.

There are three different Scooba models, the 330, 350, and 380. They cost US $299, $399, and $499 each. The Mint cleaner price isn't set yet, but Evolution has stated that it will be "under $250."

As you can see, these two cleaning robots have much less in common that would appear at first glance. One mops your floor, while the other one is more of a sweeper. They have very different ways of cleaning and navigating around the room. So how is the Mint really going to stack up against iRobot's products? I guess time will tell. The Mint cleaners are supposed to become available in the third quarter of 2010. We'll see then. In the meantime, here is a site with more information about the various robot vacuum cleaners. They also have more information about the Mint Automatic Cleaner.