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Cannot connect to Jackal clear path from my laptop

asked 2018-07-11 05:54:54 -0600

dkrivet gravatar image

I have successfully connected the jackal robot to a wifi network by ssh ing to the jackal through an ethernet cable, so my robot has a working internet connection. When I follow the steps outlined in the clear path tutorial at this link and then do rostopic list, I get the error message: "ERROR: Unable to communicate with master!"

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answered 2018-07-11 06:33:16 -0600

pavel92 gravatar image

You need your computer to be able to connect to Jackal’s ROS master. This means you need to set the jackal as ROS master. In order to do this you need to do the following:

Open a new terminal on your machine and enter:


Here you need to find your Ethernet IP. It will be something like 192.168.x.x

eth0      Link encap:Ethernet  HWaddr 09:00:12:90:e3:e5  
      inet addr: Bcast:  Mask:
      inet6 addr: fe80::a00:27ff:fe70:e3f5/64 Scope:Link
      RX packets:54071 errors:1 dropped:0 overruns:0 frame:0
      TX packets:48515 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000 
      RX bytes:22009423 (20.9 MiB)  TX bytes:25690847 (24.5 MiB)
      Interrupt:10 Base address:0xd020

Then in an ssh-ed window type ifconfig again and find the Ethernet IP which is also 192.168.y.y
Then open a new terminal on your machine and type:

sudo nano /etc/hosts

Here you need add the jackal IP and the host name for the jackal. For example like :

192.168.y.y cpr-jackal-0001

where you replace .y.y with what you got with ifconfig in the ssh-ed window. After this you can create a simple bash script called with only the following lines inside:

export ROS_MASTER_URI=http://cpr-jackal-0001:11311  # Jackal's hostname
export ROS_IP=192.168.x.x                           # Your laptop's ethernet IP address

where you replace .x.x with what you got with ifconfig in the first step.
Now for every terminal that you want to use/connect with the jackal's ROS master you just need to source the file you created like:


After this when you type rostopic list your should get the published topics.

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This has worked. Thank you very much!

dkrivet gravatar image dkrivet  ( 2018-07-11 07:46:48 -0600 )edit

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Asked: 2018-07-11 05:54:54 -0600

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Last updated: Jul 11 '18