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Hi

This is a nice extension to a good tutorial. If you can understand how to fix this, you're well on your way...
Can I suggest next time writing a more detailed subject? e.g. "connecting turtlesim teleop to turtlesim mimic"

Here's how to debug it:

When you run the teleop node, do:

$ rostopic list

and you'll see that it outputs to the topic:

/turtle1/command_velocity

But earlier in the tutorial, you sent a command to the turtle manually on the topic:

/turtlesim1/turtle1/command_velocity

using the command:

rostopic pub /turtlesim1/turtle1/command_velocity turtlesim/Velocity -r 1 -- 2.0 -1.8

So therefore you need to launch the teleop node, and re-map the output from the teleop node to the command topic of the first turtle

Here's a launch file with the existing code to start two turtles, plus it launches the teleop node and remaps the teleop topic:

<launch>

<group ns="turtlesim1">
<node pkg="turtlesim" name="sim" type="turtlesim_node"/>
</group>

<group ns="turtlesim2">
<node pkg="turtlesim" name="sim" type="turtlesim_node"/>
</group>

<node pkg="turtlesim" name="mimic" type="mimic">
<remap from="input" to="turtlesim1/turtle1"/>
<remap from="output" to="turtlesim2/turtle1"/>
</node>

<node pkg="turtlesim" name="teleop" type="turtle_teleop_key">
  <remap from="/turtle1/command_velocity" to="/turtlesim1/turtle1/command_velocity"/>
</node>

</launch>

Would you like to add this to the end of the tutorial on the Wiki?