Re: [Playerstage-users] More vfh problems...

[ahoward <ah...@po...>]

Hi Lynne:

You just need to periodically re-compute the VFH goal in the odometric
coordinate system; e.g.:

   goal_robot = goal_amcl - robot_amcl
   goal_odom = goal_robot + robot_odom

The first step takes the robot and goal pose in the AMCL coordinate system
and computes the goal pose relative to the robot.  The second step then
computes the goal pose in the odometric coordinate system, given the
robot's odometric pose.  The (-) and (+) operators indicate the standard
2D coordinate transforms.

	A.



On Tue, 9 Dec 2003 pa...@cs... wrote:

> Hi,
>
> We're having problems with vfh failing due to odometry drift over long
> distances (30m or so).  (It works for a while, but then the odometric
> origin has drifted so much that the vfh doesn't drive the robot in the
> right direction.)  We have tried resetting the vfh odometry to the
> laser-based localized global position (using SetOdometry(curr_global_x,
> curr_global_y, current_global_theta), but it doesn't stick -- the values
> keep going back to the original odometery.   We have also tried resetting
> the pos odometery, but this makes our laser positioning go haywire.
>
> The question is how to give a relative goal to vfh if the odometry origin
> is drifting over time.  If we can't reset the odometry without making the
> laser localization go crazy, then it is unclear how to keep vfh working
> over long distances.
>
> Any advice would be appreciated.
>
> --Lynne
>
>
>
>
>
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Andrew Howard                           email: ah...@po...
Department of Computer Science          http:  www-robotics.usc.edu/~ahoward
University of Southern California       phone: 1 (213) 740 6416
Los Angeles, CA, U.S.A. 90089-0781      fax:   1 (213) 821 5696
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