Dear Eitan,

Thanks for your inline reply.
What I meant by "I should combine the odometry with the external localization 
input" is that whether I should write a node similar to "robot_pose_ekf" to fuse 
odometry data with external localization system data.
Anyway, I will try to implement what you suggested and hope I can get back to 
you if there are problems.

Thanks again
Peshala




________________________________
From: Eitan Marder-Eppstein <eitan@willowgarage.com>
To: User discussions <ros-users@code.ros.org>
Sent: Thursday, December 2, 2010 2:28:24
Subject: Re: [ros-users] Navigation with existing localization

Peshala,


On Tue, Nov 30, 2010 at 10:33 PM, Peshala Jayasekara <peshala_24@yahoo.com> 
wrote:

Dear all,
>
>I want to move a Pioneer2Dx using the ROS navigation stack in a desired path 
>(eg. say a circle)
>However, we already have an accurate ultrasonic localization system.
>
>Can someone give an idea how I would use the nodes of navigation stack (without 
>using the amcl  for laser based localization).
>- which nodes should I be using?
>

You should be able to just swap out amcl for your ultrasonic localization system 
as long as your system publishes a transform to tf from the map to odometric 
frame. So in the picture 
here, http://www.ros.org/wiki/navigation/Tutorials/RobotSetup#Robot_Setup, you'd 
just swap out amcl for your node.

- I think I can avoid obstacles using only the sonar sensors of the robot
>

You can use sonar sensors to avoid obstacles... you can use any sensor you like 
as long as you have a way to convert readings to PointCloud messages. For sonar, 
this might involve creating a line of points for each sensor reading 
corresponding to the cone size at the hit point.

- I should combine the odometry with the external localization input
>

I'm not sure if I'm interpreting this correctly, but you could use odometry 
information to help your external localization system. However, its not 
necessary for things to work as long as your localization system publishes to 
tf.

Hope this helps,

Eitan


>I managed to keyboard-teleop the Pioneer using p2os stack and it works fine.
>
>Need some help on this.
>
>Thank in advance
>Peshala
>
>
>
>
>_______________________________________________
>ros-users mailing list
>ros-users@code.ros.org
>https://code.ros.org/mailman/listinfo/ros-users
>
>