Use multiple tractors

[lidiaxp]

I try add two tractors in a simulation. But just appear topics for one tractor. How can I add two tractor and control them?

[AmyPhung]

The simulator as-is isn't really designed to support multiple tractors, but with some edits it should be possible. I think the issue right now is that there are a quite few places where global namespaces are used (for ex: the ackermann and hitch controller nodes, and in the tf tree). I can look into fixing the namespaces the next chance I get, but just wanted to share this info now in case it helps

[lidiaxp]

Where change names of tf and hitch nodes?

[AmyPhung]

For the hitch node, the hitch controller script should be edited so that the subscribers aren't hard-coded to one topic - for example, you'd want to edit this script such that it uses something like /gazebo/tractor1/tractor_sim_base_link and /gazebo/tractor2/tractor_sim_base_link instead of /gazebo/tractor_sim_base_link - ideally, this should be settable from the launch file so that these namespaces can be adjusted all in one place.

For tfs, I haven't tried this before, but according to this the robot state publisher has a tf_prefix parameter that can be set from the launch file - I think setting the tf_prefix parameter equal to something unique for each tractor in this launch file might help fix that issue.

This thread might also be helpful: https://answers.ros.org/question/41433/multiple-robots-simulation-and-navigation/

[lidiaxp]

Do u know why when I change the namespace of the group the simulator does not open? The only namespace accepted is "/"