[ros-users] running move_base and stageros at 100Hz

[Eric Perko]

It actually looked like it was a problem where one part of Stage was
advancing by timesteps of 0.1 seconds at 20Hz (this would be whatever
determines where the robot ends up in the Stage GUI and therefore where the
data is simulated from) and another part of Stage was advancing by timesteps
of 0.05 seconds at 20Hz (the position model that actually reports a location
in order to simulate odometry). Basically, we'd tell the robot to go 2.5
meters forward, the odometry that ROS was outputting based on the position
model would report 2.5 meters forward, but the robot would have moved 5
meters forward in the Stage GUI. It was always a multiple of the new update
rate/10Hz... so for example it moves twice as far with a 20Hz update as a
10Hz update. It was quite entertaining to watch the robot teleport around
with an update rate of 50 or 100Hz :)

We never did find the exact spot that was causing the problem even after
digging through a good bit of the Stage source, but it looked like 10Hz was
pretty well assumed throughout all of Stage.

- Eric

On Tue, Nov 30, 2010 at 7:07 PM, Eitan Marder-Eppstein <
eitan at willowgarage.com> wrote:

> That makes a lot more sense. I guess missing the "0.1" would mean you think
> that you can accelerate faster than you actually can up to some maximum
> speed, but that maximum speed should still be the same as at 10Hz once you
> reach it. That sounds like a real pain to find.
>
> -Eitan
>
>
> On Tue, Nov 30, 2010 at 4:03 PM, Eric Perko <wisesage5001 at gmail.com>wrote:
>
>> Fred,
>>
>> We ran into the Stage simulation time thing as well. See this thread on
>> the Player-Stage list for some details:
>> http://old.nabble.com/Stage-Update-Rate-td29948041.html .
>>
>> Suffice to say, there are indeed parts of Stage that assume a 10Hz update
>> rate and, when that update is different, can cause your robot to move at a
>> multiple of normal speed within Stage (while still reporting the correct
>> velocities.. it was fun trying to figure that one out).
>>
>> - Eric
>>
>> On Tue, Nov 30, 2010 at 6:39 PM, FrederikHeger <frederik.heger at vecna.com>wrote:
>>
>>>
>>> I am trying to switch from running move_base with the default
>>> trajectory_planner_ros and a stage simulation at 10Hz (working) to the
>>> same
>>> thing but running at 100Hz. This is in preparation of running things on a
>>> real robot in the future.
>>>
>>> I changed the controller_frequency parameter in move_base.xml (changed to
>>> 100) and the interval_sim parameter (changed to 10) in the world file
>>> used
>>> for stage. I also noticed a number of places in trajectory_planner.cpp
>>> where
>>> ".1" was hardcoded as the time increment. I changed those to ".01".
>>>
>>> Trying to run what used to work at 10Hz, I now see a robot that moves way
>>> faster than it did before. It looks like there is still something
>>> assuming
>>> things are running at 10Hz.
>>>
>>> Any suggestions on where to look or how to approach this issue better
>>> would
>>> be appreciated.
>>>
>>> Thanks,
>>> Fred
>>> --
>>> View this message in context:
>>> http://ros-users.122217.n3.nabble.com/running-move-base-and-stageros-at-100Hz-tp1996011p1996011.html
>>> Sent from the ROS-Users mailing list archive at Nabble.com.
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>>
>>
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