How to use the branch add_link branch of ardupilot in ubuntu20.04&&gazebo9

I started gazebo with

cd bluerov_ros_playground
source gazebo.sh
source ~/.bashrc
gazebo --verbose worlds/underwater.world -u

got the following error

[Err] [ArduPilotPlugin.cc:488] [BlueRov2] Please specify a jointName, where the control channel is attached.
[Err] [ArduPilotPlugin.cc:497] [BlueRov2] Couldn’t find specified joint [ ]. This plugin will not run.

By reading previous articles,I found that the reason for the problem is that i didn’t use the branch add_link branch of ardupilot. Because my ubuntu versionis 20.04,i can only insatll gazebo9.x or higher.
So i git ardupilot_gazebo from GitHub - khancyr/ardupilot_gazebo. which is not same as GitHub - patrickelectric/ardupilot_gazebo at add_link . and i don’t know how to use the branch add_link branch of ardupilot to install ardupilot_gazebo by git clone in khancyr/ardupilot_gazebo.
could you please help me to figure out how to solve this error, this is very important for me,and hope guys forgive me for my poor English.

Hi @showmaker1, welcome to the forum :slight_smile:

From what I can tell the add_link branch is created by @patrickelectric and only exists in his fork of the repository, so unless you copy or cherry-pick those changes over then you won’t be able to use them in a clone of khancyr’s repository.

Have you tried getting Patrick’s version of the code instead of khancyr’s one? That should be possible with

git clone -b add_link https://github.com/patrickelectric/ardupilot_gazebo

Hi @showmaker1,

The add_link branch was a contributions that is not merged on khancyr repository, It’s necessary to use it for the underwater demo.

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