>
> 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.


We are leaving in really exciting times. Just 3 months ago the most
affordable alternative for running navigation stack with SLAM was iRobot
with Hokuyo.  About $2,000 total.

And now we have not one but two extra options:
1) Neato with their sensor $400.
2) iRobot + Kinect $300 - $400

Another $300 for brain/mics and you have a sub-$1000 robot hardware.
Add to this the great work all you guys were doing on the software side, and
the advent of Personal robotics looks a lot closer.

Alex Bravo
P.S. It would be nice if Neato would release their specification too. Are
you listening, Neato? :)


> 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@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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