ROS2 Port

[mikeferguson]

I've started working on this (https://github.com/mikeferguson/robot_controllers/tree/ros2) but figured I'd post a note here until we get a ros2 branch going on this repo.

Roadmap:

• Port robot_controller_msgs
• Port robot_controllers_interface
  • Port ControllerLoader
  • Port ControllerManager
  • Port Handle and derived classes
  • Move Controller, Handle(s), Manager, Loader classes into robot_controllers_interface namespace (this was arguably a bug in the original ROS1, which required all downstream controllers to depend on robot_controllers rather than robot_controllers_interface).
  • Change ControllerManager to use service rather than action. The interface is a lot cleaner, and in ROS2 services can be asynchronous, so the deadlock fears in ROS1 are gone.
  • Port python scripts
• Port robot_controllers
  • cartesian_pose
  • cartesian_twist
  • cartesian_wrench
  • diff_drive_controller - planning to still tweak a few things still
  • follow_joint_trajectory
  • gravity_compensation
  • parallel_gripper - ported, not yet fully tested
  • pid
  • point_head
  • scaled_mimic
  • trajectory tests
• Add documentation to README that shows how to use updated interfaces

Bugs/Improvements to Look At:

• Need to test cancellation of actions - probably need to change aborted() to cancelled() for them as well.
• Add a dynamic parameter interface to the PID class. Moved to ROS2: add dynamic parameter interface to PID #50

[mikeferguson]

migration docs are in: #49

[mikeferguson]

PID dynamic parameters is now ticketed here: #50

[mikeferguson]

parallel gripper now tested - we should now have feature parity with ROS1