Use the urdf_ to set the robot_description in admittance controller

[SyllogismRXS]

I'm running ROS2 Iron, building ros2_control and ros2_controllers from their master branches, but the admittance controller was complaining about the lack of the robot_description parameter in kinematics_interface_kdl (https://github.com/ros-controls/kinematics_interface/blob/master/kinematics_interface_kdl/src/kinematics_interface_kdl.cpp#L34).

The controller_manager now requires that the robot_description to not be a parameter, but come from a topic. I'm doing that. However, it seems that the admittance controller is still expecting robot_description as a parameter. In this PR, I set the robot_description parameter for the admittance controller using the urdf_ member variable. This feels a little hacky. Am I doing something wrong? Is anyone using the latest admittance controller successfully?

Thanks!

[pac48]

@christophfroehlich I agree that passing the robot description in the initializer makes sense.

[christophfroehlich]

@SyllogismRXS could you please add this change to the kinematics_interface first, and then update this PR here?

[SyllogismRXS]

I modified the kinematics_interface package to accept the robot_description as an input argument with a fallback to using the node's parameters if the robot_description is empty: https://github.com/ros-controls/kinematics_interface/pull/66

[destogl]

Closed in favor of #1247