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Can see topic published but cannot see anything when we echo the topic

asked 2017-03-16 22:22:26 -0600

Azhar gravatar image

I am working on a tele-operation mode of a mobile robot, from a control station.

The control station and the robot is connected to the same WIFI network and both can ping to each other.

The problem comes when i want to see the LIDAR map/readings on the control station.

When i rostopic list on my control station, i could see the topic. However, when I echo that topic, i didn't receive any message. When i open RViz and add the map , it doesn't show anything(because the message wasn't received in the first place). RViz freezes too when i try to add the map. This does not happens to the other topics. For eg, the topic odom can be echo-ed.

I tried with Ethernet , it works(but it has its own issues ), but i need to be connected through a same WIFI network.

What could be the problem here??

1) Too much data being published?(when i do a rostopic echo in the vehicle, my screen would be flooded with values)

2) WIFI connection? (i set up a bidirectional networking by exporting ROS_IP and ROS_MASTER_URI, do i have to do anything else?)

3) RViz issues? (it freezes, turns grey when i try )

4) Any other things i am missing out?

and possible solution for this?

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What is your ROS_MASTER_URI and ROS_IP on both computers?

NEngelhard gravatar imageNEngelhard ( 2017-03-17 03:19:49 -0600 )edit

ok.

A : Control station, my laptop B: mobile robot

in A,

export ROS_IP=<IP address of A>

export ROS_MASTER_URI=http://<IP address of B>:11311/

in B (MASTER),

export ROS_IP=<IP address of B>
roscore
Azhar gravatar imageAzhar ( 2017-03-17 03:44:58 -0600 )edit

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answered 2017-03-20 10:57:22 -0600

Azhar gravatar image

I solved the issue by downloading the LIDAR MAP(.yaml ) in my laptop and run from there. Thanks people. I encountered a new problem which i will be opening a new question on.

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Asked: 2017-03-16 22:22:26 -0600

Seen: 293 times

Last updated: Mar 20 '17