[ros-users] iRobot - Roomba vs Create

Máté Wolfram mate.wolfram at gmail.com
Wed Nov 9 17:33:59 UTC 2011


We just recently purchased a Roomba 555 + Turtlebot equipment and have
been asking ourselves why the odometry is so disappointing. A quick
measurement resulted in an error of +2 meters on a 2 meter run (!).
Obviously, this renders the robot unable to create usable maps.

Goncalo, you stated in your initial post that you encountered a
similar problem with a couple of Roombas. Did you manage to solve it?
Is it likely to be a production failure?

kind regards,

2010/12/5 Jenkins, Odest Chadwicke <odest_jenkins at brown.edu>:
> I do not really think there is much difference between using the
> Roomba and the Create.  We have used the Create and a number of
> variations on the Roomba over the last 5 years.  Translating between
> the two open interface descriptions is relatively simple.
> I believe the Create is a better bargain because the Roomba incurs the
> extra cost (and weight) of a vacuum.  The 25-pin port is also nice for
> powering onboard computing.  The additional wheel on the back of the
> Create is useful for keeping the base steady.  All of this said, both
> platforms have performed well for our needs.
> It is disappointing that iRobot does not sell the Create in Europe.
> I think the real question now is using the Create/Roomba versus the
> Neato and other next gen vacuums:
>  http://www.engadget.com/2010/11/29/neato-xv-11-robot-vacuum-gets-its-very-own-open-source-lidar-hac/
> -Chad
> Date: Sat, 4 Dec 2010 11:22:15 -0800
> From: Ken Conley <kwc at willowgarage.com>
> Subject: Re: [ros-users] iRobot - Roomba vs Create
> To: User discussions <ros-users at code.ros.org>
> Message-ID:
>       <AANLkTinxinvGvxmwXCVyL7ocar8VwEwwxFMpUSioJNgi at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> FYI: We're starting an effort here at WG to use Creates.  We didn't
> benchmark against the Roombas, and perhaps some of those will end up
> in our arsenal as well.  Also, we've noticed Gon?alo's great
> documentation coming online, so we hope we can build on each other's
> efforts.  We're using it to integrate some of our main libraries
> (navigation, OpenCV, PCL) into a low-cost platform.  We've already
> posted our Kinect + Create tutorial, which is part of this effort.
> One main difference between the Creates and the 500 series is (IIRC)
> that you can't read the raw encoder counts off the Create. The Open
> Interface for the Create only goes up to Packet 42. The 500 Open
> Interface adds Packets 43-58, which include encoders, light bumper,
> motor currents, and stasis caster. I assume this means the odometry
> with the Create will be worse, but, like Gon?alo, I don't have
> experience with both.
> Our driver right now is in Python and uses Damon Kohler's PyRobot,
> plus bits and pieces for other ROS drivers.  The stack is still a work
> in progress and will move soon, but for now you can find it here:
> https://code.ros.org/svn/ros-pkg/branches/trunk_cturtle/stacks/create_robot/
>  - Ken
> 2010/12/4 Gon?alo Cabrita <goncabrita at gmail.com>:
>> Hi Alex,
>> Hope you don't mind I started a new thread for this.
>> Buying the Roomba instead of the Create was not an option for us. At first
>> we were aiming for the Create since it was designed having research in mind,
>> but the Portuguese iRobot reseller told us we could only acquire the Create
>> on the United States. So we got a sweet deal on a bunch of Roombas instead.
>> Let it be clear that I never worked with a Create in my life, so I cannot
>> make a comparison between both robots.
>> When we first got the Roombas we had some trouble with the odometry... ok a
>> lot of trouble! The Roombas have very poor encoders, single channel, 4
>> pulses per motor shaft turn (I believe direction is determined from the
>> motor speed, I don't think you can even call this an encoder). Also,
>> initially we were getting distance travelled and amount turned from the
>> robot, which resets after each read, so at the speed we were polling the
>> Roomba (10Hz) and due to the low resolution on these values (1 degree for
>> the angle for example), we were getting really bad odometry readings. Later
>> we decided to poll the encoder counts instead, which greatly improved our
>> odometry (this is how the roomba_500_series package works) however we bumped
>> into another problem. Usually encoder counts increase as the wheel moves
>> forward and decrease as the wheel moves backwards. However on some Roombas
>> encoder counts only increase. You can still make a quick fix using the motor
>> speeds as an indicator of the wheel direction, but the odometry on these
>> robots is far worse. Now that i think of it, this should go into the
>> roomba_500_series troubleshoot section! We recently got a batch of 555, non
>> of them seem to have this problem. However some of the 530 and 560 we have
>> suffer from the "crappy" encoder problem.
>> Globally the Roomba is a very robust platform, it can take a lot of beating.
>> It also brings a nice package of sensors and actuators. iRobot 's
>> documentation on the communication protocol is very good, you get access to
>> pretty much everything the Roomba has. The docking station is very cool, we
>> love it. The battery usually holds for 2-3 hours pumping juice to the Roomba
>> and an Hokuyo laser. We run it with the ROS navigation_stack and it moves
>> without problems
>> Finally I guess for the money we spent we couldn't expect better, the value
>> for money is great, specially for us, we have a lot of Roombas for swarm and
>> multi-robot experiments. You can't compare it to a robot designed
>> specifically for research though.
>> Now I guess people who are using the Create could give their opinion on this
>> matter :)
>> Hope this helps!
>> Gon?alo Cabrita
>> ISR - University of Coimbra
>> Portugal
>> On Dec 4, 2010, at 6:01 PM, Alex Bravo wrote:
>> Goncalo,
>> I've been looking at the package you created for Roomba
>> 560?http://www.ros.org/wiki/roomba_500_series
>> and I just wanted to say thank you for such an excellent job!
>> We are considering purchase of iRobot and wondering if extra expense of
>> Roomba 535/560/570 is worth it compared to iRobot Create. We also see that,
>> say Brown University still uses iRobot Create.
>> Considering your experience (if I remeber correctly, you were mentioning
>> those robots a year ago), what are you thoughts on the
>> advantages/disadvantages between those models?
>> Thank you,
>> Alex Bravo
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