[ros-users] Navigation stack: issue about ground plane detection

[Eitan Marder-Eppstein]

Xiaojun,

Tully's right, we do a fair amount of work on the PR2 with calibration to
make sure that things work. Even with that, we have some problems with false
positives from time to time in our ground plane detection. The plan is to
write a more robust filter at some point, but I'm not sure exactly when
we'll get to that. You might have to write a different filter that works for
your robot. Wish I had a better answer for you.

Hope all is well,

Eitan

On Wed, Oct 20, 2010 at 5:10 PM, Tully Foote <tfoote at willowgarage.com>wrote:

> Xiaojun,
>
> It does sounds like you need to make sure your filters are setup
> accurately.  On the PR2 we have optical flags for calibration on all
> joints.  Plus we do full body and sensor calibration to make sure they are
> aligned.  Also you will likely need to look at more parameters of the ground
> plane removal that you need to customize for your robot.
>
> Tully
>
>
> On Wed, Oct 20, 2010 at 8:10 AM, clarkwu <wu.xiaojun at gmail.com> wrote:
>
>>
>> Eitan,
>>
>> Thanks for your reply.
>>
>> You are right that the warning message refers to something wrong in the
>> laser filters.
>> What I found is in the source file sac_inc_ground_removal_standalone.cpp,
>> there are a few default settings for PR2 robot, such as
>> the robot_footprint_frame is "base_footprint"
>> the laser_tilt_mount_frame is "laser_tilt_mount_link"
>> the goal frame id for point cloud is "odom_combined"
>> and the function updateParametersFromServer() in fact doesn't update the
>> above parameters.
>>
>> So I changed the codes for our own robot accordingly, and the
>> sac_inc_ground_removal_node node now runs properly!
>>
>> Yet the result of topic /ground_object_cloud looks not so perfect, i.e.,
>> there are part of the ground close to the robot still left within the
>> point
>> cloud of this topic. I also observed that in the output of
>> tilt_scan_shadow_filtered, the ground plane is not exactly in horizontal
>> level but looks more like a slope. So I guess this means the tilt
>> controller
>> need further calibration to make sure its "0" position refers to the true
>> horizontal plane.
>>
>> How did you handle this issue for PR2 robot?
>>
>> thanks
>> xiaojun
>>
>>
>> --
>> View this message in context:
>> http://ros-users.122217.n3.nabble.com/Navigation-stack-issue-about-ground-plane-detection-tp1707477p1739332.html
>> Sent from the ROS-Users mailing list archive at Nabble.com.
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>
>
>
> --
> Tully Foote
> Systems Engineer
> Willow Garage, Inc.
> tfoote at willowgarage.com
> (650) 475-2827
>
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