[ros-users] Clear cells in costmap with max laser range

[Roderick de Nijs]

Thanks Eitan, Brian for the help,

In outdoor environments I have no other option but to clear. Since I 
want the robot to navigate down
the sidewalk, it should be able clear the cells in this direction.

Good idea the filter+clearing, seems doable :)



On 07/16/2010 09:00 PM, ros-users-request at code.ros.org wrote:
> Roderick,
>
> Its actually not the costmap that is ignoring max_scan_range values from the
> laser, its the laser projector that takes a laser scan and turns it into a
> point cloud. The reason for this is that there is no guarantee that
> max_scan_range actually corresponds to the laser not seeing anything. It
> could be due to min_range, a dark object, or another error condition... all
> the laser knows is that it didn't get a return for one reason or another.
>
> With this said, if you want the costmap to assume that error values are OK
> to use for clearing, you can write a filter for the laser scan which takes
> all the max_range values and sets them to something slightly less than
> max_range. Then, you can configure the costmap to use that filtered scan for
> clearing operations. I did this on the cart_hackathon sprint that we did
> here at Willow, but I can't seem to find the filter I wrote... I think I was
> pretty sleep deprived at the time. However, it should be a really easy one
> to recreate if you feel compelled.
>
> For documentation on filters see:http://www.ros.org/wiki/filters
>
> For examples of laser filters see:http://www.ros.org/wiki/laser_filters
>
> Hope this helps,
>
> Eitan
>    


-- 
Dipl-Ing Roderick de Nijs | rsdenijs at tum.de
Institute of Automatic Control Engineering (LSR)
Technische Universitaet Muenchen, D-80290 Munich, Germany
tel: +49(89)289-23416 | http://www.lsr.ei.tum.de