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Making Maps Using Stage's Wander Controller

SLAM Using Stage's Wander Controller

SLAM can be realised using wander controller in stage. The robot can move around and avoid obstacles by the virtue of the wander controller, the mapping tools can be used to get 2D map of the environment.

It is worth a note that this tutorial works only for one robot, multirobot SLAM is not within the scope of this tutorial.

Codes

Download the codes from http://mobotica.googlecode.com/files/stage_controllers.tar.gz and extract the stage_controllers file and make sure that it is in the ROS path.

Build the package;

rosmake stage_controllers

Start the stage simulation

Start an instance of the master and start the stage simulation in a new terminal window

rosrun stage stageros `rospack find stage_controllers`/world/roomba-wander-slam.world

NOTE: The world file employs stage controller 'wander' hence the robot will start to move immediately and will be in a wandering mode. For more details on the 'wander' controller, see here - http://www.ros.org/wiki/stage/Tutorials/IntroductiontoStageControllers

Start gmapping

Start gmapping in a new terminal window

rosrun gmapping slam_gmapping scan:=base_scan

Start map server

Start map server in a new terminal window

rosrun map_server map_saver

The map will get saved in the directory from where the command for map_server is issued, as a pgm file. The map may be visible by clicking on it while the simulation is running, run the simulation till a desired level of accuracy has been attained.

Results etc

A sample result;

A shortcoming of this approach is that, the robot being in 'wander' mode prefers open spaces compared to narrow lanes. So, one may have to be patient until the robot covers those congested parts of the environment thus yielding a better map.

The rxgraph of this simulation shows the nodes in use;