[ros-users] Important Navigation Message

[Eitan Marder-Eppstein]

Hitesh,

It is definitely possible that the robot overshoots the path with incorrect
acceleration limits because the robot will assume that it can slow down
faster than it actually can. When running the planning loop at a reasonable
speed, this problem will be somewhat mitigated because the planner always
takes the velocity of the robot reported by odometry into account when
creating a new plan rather than the velocity it last commanded, but I
wouldn't be surprised to see degraded performance.

Eitan

On Fri, May 28, 2010 at 10:19 AM, hitesh dhiman <
hitesh.dhiman.1988 at gmail.com> wrote:

> Hi Eitan,
> Any idea what effect might this have on the robot's trajectory? Is it
> possible that the robot will overshoot it's designated path if the path
> planning is not updating quickly?
>
>
> On Sat, May 29, 2010 at 12:39 AM, Rob Wheeler <wheeler at willowgarage.com>wrote:
>
>>  Eitan meant to say:
>>
>>  acc_lim_th: my_th
>>  acc_lim_x: my_x
>>  acc_lim_y: my_y
>>
>> Sorry for the confusion.
>>
>> -R
>>
>>
>> On Fri, May 28, 2010 at 8:38 AM, Eitan Marder-Eppstein <
>> eitan at willowgarage.com> wrote:
>>
>>> Hey all,
>>>
>>> So, I screwed up pretty nicely in the
>>> http://www.ros.org/wiki/navigation/Tutorials/RobotSetup tutorial and
>>> gave example parameters that do not actually match those read by the code. I
>>> imagine that this means many of you are using the default acceleration
>>> limits for your robots rather than the ones you meant to set. If your
>>> configuration for the base_local_planner includes the following spellings of
>>> the acceleration limit parameters:
>>>
>>>  acc_limit_th: my_x
>>>  acc_limit_x: my_y
>>>  acc_limit_y: my_th
>>>
>>> They will be ignored by the code and you'll need to switch to:
>>>
>>>  acc_lim_th: my_x
>>>  acc_lim_x: my_y
>>>  acc_lim_y: my_th
>>>
>>> As specified here: http://www.ros.org/wiki/base_local_planner#Parameters
>>>
>>> Again, I apologize for this and I've fixed the documentation. I'm also
>>> going to take some time today to go through all the launch files I can find
>>> in our repositories fixing this error. I'm pretty sure that I copied the
>>> wrong text along with the rest of the world in at least a few places.
>>>
>>> Truly sorry again... I just want to make sure that as many people as
>>> possible hear about this mistake as possible.
>>>
>>> Hope all is well and that this fixes at least one or two puzzling
>>> problems,
>>>
>>> Eitan
>>>
>>> _______________________________________________
>>> ros-users mailing list
>>> ros-users at code.ros.org
>>> https://code.ros.org/mailman/listinfo/ros-users
>>>
>>>
>>
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>>
>
>
> --
> Regards,
> Hitesh Dhiman
> Electrical Engineering
> National University of Singapore
>
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>
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