Uuv_simulator: Multi Robot TF tree broken

Hi @HashirZahir I did not have time yet but I'll try to reproduce your error and find a solution

@HashirZahir I'm also interested in this same problem. Im attempting to launch 3 Eca_a9 vehicles simultaneously in the same manner after running _roslaunch uuv_gazebo_worlds ocean_waves.launch_. I can get at most two Eca_a9 vehicles working at once -- Have you had any further progress on this issue?

Could you share the steps to replicate to get the 2 Eca_a9 vehicles running together (and their respective TF trees?) In my case I am able to spawn both vehicles in the simulation but the TF tree is broken / disconnected, making it harder to perform multi-auv calculations/algorithms

Any luck @pxalcantara ?

Sorry @HashirZahir, but not yet, I've been very busy but I'll try to check this week.

Could you share the steps to replicate to get the 2 Eca_a9 vehicles running together (and their respective TF trees?) In my case I am able to spawn both vehicles in the simulation but the TF tree is broken / disconnected, making it harder to perform multi-auv calculations/algorithms

Sorry for the slow response. I have a launch file for launching 3 (or more) Eca UUVs under different namespaces using the upload.launch. I use another launch file to launch the geometric tracking controller for each of the 3 vehicles. Without knowing why, this generally works for 2/3 UUVs, with the 3rd being unresponsive and broken (as you have described)... So I can control, send waypoints, echo all topics for 2 UUVs. Note that this isn't always consistent and sometimes only one UUV will spawn correctly. I unfortunately don't have any more insight to the issue.

Has anyone managed to gain any insight on this issue? Multi-Robot capabilities of this simulator are amazing but I feel like some simple TF tree script is causing the broken TF tree, although I have not been able to find the source of the issue.

@HashirZahir
I was having the same issue as @Joel-Lindsay with broken links with the eca_a9s. I fixed this by editing the file /eca_a9/eca_a9_description/robots/eca_a9_default.urdf.xacro.

inertial_reference_frame="$(arg inertial_reference_frame)"
was changed to:
inertial_reference_frame="world"

This fixed my tf trees which also were disconnected.

Hi, @ErinWetter do you mind sharing a picture of the connected TF tree?

Here is the top of a tf tree with 4 working eca_a9:

Going down to only two vehicles we can see the base link:

I haven't figured out why the frame links between broadcasters: ground_truth_to_uuv# and /uu#/robot_state_publisher were not connecting before hardcoding the robot state publisher to match but I'm not familiar with the xacro/urdf robot model creation process.

I had run some tests on a single vehicle comparing the order of launching the broadcasting nodes on the Eca and RexRov (which has not had the broken tf tree issues and I've been using for multi-vehicle simulations). For a single Eca_a9, the tf tree would be severed at /base_link if I started the /ground_truth_to_uuv# node in terminal rather than within the "upload_eca_a9.launch" file. While doing the same with the RexRov /base_link connected with all launch conditions.