PR2 move_base how to get map

asked 2013-01-17 04:49:36 -0500

jys

212 ●19 ●26 ●30

updated 2014-11-22 17:05:39 -0500

ngrennan
1 ●1 ●1

I bring up pr2 in Gazebo with

roslaunch pr2_gazebo pr2_emtpyworld.launch

PR2 comes up and I want to use move_base programatically to move it to some (x,y) coordinate. So I tried to bring up move_base server with following..

rosrun move_base move_base

But it asks for map, the tutorials in pr2_simulator and navigation stack only talk about pre-defined maps.

[ INFO] [1358441051.857729791]: Subscribed to Topics: 
[ INFO] [1358441051.868857033]: Requesting the map...
[ INFO] [1358441051.870152566]: Still waiting on map...

Is it possible to get a map out of Gazebo? Or, am I suppose to be manually creating a map file? I read similar questions on this forum, but still confused.. Since I am fairly new to ROS/ navigation stack / map, please refer to specific example. Thanks!

answered 2013-01-17 05:55:02 -0500

dornhege

31395 ●134 ●284 ●498

You'll need to build a map using SLAM, unless you want to create that by hand. See, e.g. this tutorial:

http://www.ros.org/wiki/pr2_simulator/Tutorials/BuildingAMapInSimulation

Other alternatives are to use the /odom frame for navigation, but that will drift over time on a real robot, so you can't drive to a specific x,y then.

However, building a map and localizing in it will only work if there is something in the world, i.e. it won't work for the empty world.

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Hmm.. So with pr2_empty_world.launch, I will not be able to build a map out of it. Let me try to clarify. So, in order to localize correctly, some objects must be in sight of PR2 when mapping starts. Am I understanding correctly?

jys ( 2013-01-17 05:58:48 -0500 )edit

Yes. Actually any empty image will be a correct map for the empty world. Obviously the robot can't localize if there is nothing to recognize.

dornhege ( 2013-01-17 06:03:19 -0500 )edit

Then, instead of using SLAM, is it somehow possible to use x,y location provided by Gazebo? I want to be complete sync with location coordinate inside Gazebo.. If it is possible, do you know of examples or have rough idea on how to accomplish it? Thanks!

jys ( 2013-01-17 06:11:31 -0500 )edit

For simulation you could use fake localization: http://www.ros.org/wiki/fake_localization

dornhege ( 2013-01-17 06:31:44 -0500 )edit

That looks great. But still confused.. What is correct step of launching stuff.. I launch pr2_emptyworld and run fake_localization? Is something missing inbetween? Do you know why fake_localization complains about Dropped 100.00% of messages so far. Please turn the [ros.fake_localization. blah blah

jys ( 2013-01-17 07:09:28 -0500 )edit

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