[ros-users] navigation stack bare minimums

[Mike Purvis]

>
> If you're doing a lot of multi-robot navigation and you want the robot's to
> be aware of each other's positions, you'll probably need a map frame. You
> don't necessarily need to run a map_server, but you will need to have your
> localization source, whether that be GPS, camera-based localization, or
> other, publish a transform from the map frame to the odom (or if you don't
> have odom, base_link) frame of your robot. In the case where you don't have
> a map_server... you'd still set the "static_map" parameter on the
> global_costmap to be false.


This is very helpful, thanks.


With the parameters that you posted, you should no longer receive this
> error. Can you take a look at the parameters you have set with "rosparam
> dump" to make sure that the parameters for the global_costmap are being set
> correctly? They should fall under the move_base_node/global_costmap/
> namespace.
>

Okay, yes, I've played with the namespaces, and I believe all of the pieces
are now seeing the proper parameters. Thanks for the tip about rosparam
dump.

I have a few remaining questions about global_costmap and local_costmap. I
have the navigation stack talking to my simulator, but when I send a goal, I
get the following output:

[ WARN] 1276006631.337854000: The goal sent to the navfn planner is off the
global costmap. Planning will always fail to this goal.
[ WARN] 1276006631.425825000: The goal sent to the navfn planner is off the
global costmap. Planning will always fail to this goal.
[ WARN] 1276006631.704455000: The robot's start position is off the global
costmap. Planning will always fail, are you sure the robot has been properly
localized?
[ WARN] 1276006631.825804000: The goal sent to the navfn planner is off the
global costmap. Planning will always fail to this goal.
[ WARN] 1276006631.904408000: The robot's start position is off the global
costmap. Planning will always fail, are you sure the robot has been properly
localized?
[ERROR] 1276006631.949307000: Aborting because a valid plan could not be
found. Even after executing all recovery behaviors

Now, I'm using raw UTM coordinates for my position, so the numbers are
large. My odometry messages (and corresponding transforms) look like so:

header:
  seq: 4657
  stamp: 1276006871180577039
  frame_id: odom
child_frame_id: base_link
pose:
  pose:
    position:
      x: 596506.594977
      y: 4956355.18823
      z: 0.0
    orientation:
      x: 0.0
      y: 0.0
      z: 0.922148700667
      w: 0.386835590217
  covariance: [0.0 ...

And my goal, accordingly, was sent like so:

rostopic pub /clearpath/robots/0/move_base_simple/goal
geometry_msgs/PoseStamped '{ header: { frame_id: "odom" }, pose: { position:
{ x: 596505, y: 4956355 }, orientation: { x: 0, y: 0, z: 0.62, w: 0.78 } }
}'
publishing and latching message. Press ctrl-C to terminate

Now, I've tried to center the global costmap over this region, like so:

global_costmap:
  global_frame: odom
  robot_base_frame: base_link
  update_frequency: 5.0
  static_map: false
  rolling_window: true
  width: 100
  height: 100
  origin_x: 596500
  origin_y: 4956350
  map_type: costmap

Is this a correct approach? Alternatively, I could put a local origin in my
odometry and tf broadcasters. Would that be better? Or is there something
else entirely?

Thanks again.
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