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tf_prefix param: add to IMU Broadcaster and fix slashes in DiffDrive #1104

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@rafal-gorecki rafal-gorecki commented Apr 22, 2024

Related with #1102, rabase to master.

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@saikishor FYI

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rafal-gorecki commented Apr 26, 2024

Hi @christophfroehlich @saikishor,
I didn't notice there was errors in building, but I see that not all tests pass on the master. Which tests work and what should I do to finish this PR?

@rafal-gorecki rafal-gorecki changed the title tf_prefix param: fix slashes and add to IMU Broadcaster tf_prefix param: add to IMU Broadcaster and fix slashes in DiffDrive Apr 27, 2024
Comment on lines +65 to +82
std::string tf_prefix = "";
if (!params_.tf_frame_prefix.empty())
{
tf_prefix = params_.tf_frame_prefix;
}
else
{
tf_prefix = std::string(get_node()->get_namespace());
if (tf_prefix != "/")
{
tf_prefix += '/';
}
}
if (tf_prefix.front() == '/')
{
tf_prefix.erase(0, 1);
}

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@saikishor saikishor Apr 27, 2024

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Hello!

While reviewing this part again, I started to question myself, if we need this or not. I'm saying because in case of the diff_drive_controller, the odom message that is being published is a dynamic tf frame, but in case of the imu_state_broadcaster, as per the imu you always have a static transform link inside the URDF, I don't know if it make sense to have the tf_prefix in this case.

Right now, your changes will add namespace of the controller manager to the links, I'm not sure how right is it.

Does it make sense?. Should we check if the link exists from the loaded URDF?

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Hi @saikishor,

Thank you, for reply!

I'm not sure what difference it makes whether fame is dynamic or static in the case of tf_prefix. I treat it as an option that may be useful to someone. What I care about most is the ability to correctly assign a frame to a robot when many robots are launched.

I'm still wondering about the issue of sensor_name, because while in the case of a real robot there should be no problems, in the simulation you need to create sensor objects with different namespaces.

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Hello!

I think it is rather very important, because the sensor readings should correspond to a specific frame on the robot and this might be important. Regarding multi robot i agree that we would need this separation, then we can use the namespace, but why tf_prefix?. Moreover, i believe we have to make sure that it is a valid link.

Can you explain to me the instances that's a requirement for you?

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@rafal-gorecki rafal-gorecki Apr 27, 2024

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If you are asking specifically about tf_prefix, I don't need it, but I added it to unify arg in the packages.

As for checking whether a frame exists, it makes sense.

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What do you think about the problem with sensor_name? The simplest solution is to add a parameter that adds a namespace to sensor_name or add a sensor name prefix.

Generally, what I care about is being able to run many robots in simulation and on hardware while making a minimum number of changes to the code.

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@rafal-gorecki ok now I got the use-case. Yes, it is tricky to make it work with simulation with this namespace. What can be done is probably, instead of using the tf_prefix, just add it to the sensor_name already. I'm not sure how to automatically configure it based on the robot. The current changes however, doesn't fix it right?

Any ideas on how to solve it are welcome

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Thank you, so much for today. I will try to add this functionality soon. I would like to ask you to confirm whether this tf_prefix can be left for imu in order to standardize the packages, or should I get rid of it?

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Let's discuss your idea on how you are planning to tackle the idea of sensor name automatically, and then it's better to start changing

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@rafal-gorecki rafal-gorecki Apr 29, 2024

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  1. The best solution is probably to add some kind of standard that make robot_state_publisher with namespace add to all link reference_frame and sensor topic namespaces.
  2. Or add namespace argument to URDF and put it in all resonable field.

Then add the argument add_namespace_to_sensor_name (bool)

@saikishor what do you think?

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@rafal-gorecki rafal-gorecki May 15, 2024

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Second solution added

@mergify mergify bot mentioned this pull request May 23, 2024
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henrygerardmoore pushed a commit to henrygerardmoore/ros2_controllers that referenced this pull request Jul 19, 2024
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