[ros-users] iRobot - Roomba vs Create

Sat Dec 4 21:25:32 UTC 2010

There's still that $1,200 price tag on that URG though.
Mike, I wanted to thank you for your reply to me at Trossen many months ago
about better sutability of wheeled robots for autonomous tasks.

BTW, do you know what's happening with ArbotiX availability at Trossen?
I ordered PhantomX kit there two weeks ago and still didn't get it.

On Sat, Dec 4, 2010 at 12:46 PM, Michael Ferguson <mfergs7 at gmail.com> wrote:

> Using the brown-ros-pkg driver for the Creates we've found the odometry to
> be good enough that gmapping/amcl can handle the error (with the shorter
> range URG-04LX-UG01 lidar). However, I can't say we've gone more than maybe
> an hour during any particular run. (also, just a note, I can't seem to find
> the reference anywhere, but I seem to recall the Create encoders being 26
> cpr of the drive wheel)
>
> Mike Ferguson
> ILS Social Robotics Lab
> SUNY Albany
>
>
> On Sat, Dec 4, 2010 at 3:18 PM, Ken Conley <kwc at willowgarage.com> wrote:
>
>> 2010/12/4 Gonçalo Cabrita <goncabrita at gmail.com>:
>> > out.  Also the Create can have that green block, the Command Module that
>> I
>> > believe can be used to connect a bunch of stuff that can be accessed
>> over
>> > the iRobot OI protocol.
>>
>> We ended up not using the Command Module.  To the best of my
>> understanding, it's meant to be used as alternative to mounting your
>> own laptop.  The OI protocol appears to be disabled whenever the
>> Command Module is connected.
>>
>> > Still, bottom line, if the Roomba's odometry proves to be better I would
>> go
>> > for the Roomba. However that ROS vision odometry stack could solve the
>> > odometry problem if one could use a cheap one camera system (at the
>> expense
>> > of extra computational power, which in our case is really bad since we
>> have
>> > tiny EeePCs!!!).
>>
>> We've thought about trying the Neato XV-11's instead -- they're more
>> expensive, but you get LIDAR.  However, they don't sell stripped down
>> units nor publish their documentation like iRobot does, so we're going
>> with the Creates for now.
>>
>>  - Ken
>>
>> > Gonçalo Cabrita
>> > ISR - University of Coimbra
>> > Portugal
>> > On Dec 4, 2010, at 7:22 PM, Ken Conley wrote:
>> >
>> > 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 Gonçalo'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 Gonçalo, 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 Gonçalo 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!
>> >
>> > Gonçalo 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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