Fix stuck passive joints

[huemerj]

As mentioned in #235 and #219, a problem with passive joints was introduced by the following code line:

gazebo_ros2_control/gazebo_ros2_control/src/gazebo_system.cpp

Lines 597 to 600 in 0dc19ab

	} else {
	// Fallback case is a velocity command of zero
	this->dataPtr->sim_joints_[j]->SetVelocity(0, 0.0);
	}

As suggested by @destogl, I added a vector with flags which indicates if a joint is active (has command interfaces) or passive and subsequently sets the velocity to zero or not.

[christophfroehlich]

Thanks for the fix. I tested this with the pendulum from #172, it is working again!

[ahcorde]

Do you have any plans to port this to gz_ros_control? If you don't have time, I can do it

[ahcorde]

https://github.com/Mergifyio backport humble

[mergify]

backport humble

✅ Backports have been created

• #238 Fix stuck passive joints (backport #237) has been created for branch humble

[huemerj]

Do you have any plans to port this to gz_ros_control? If you don't have time, I can do it

I will have to set up / convert an example with passive joint for gz_sim, but I can do that.