August 2023 Meetings Aerial Robotics

Aerial Vehicles
6

Thanks for the recording. Here’s my thoughts:

  • Motivations
    • Yes, I agree with Tully; having the same messages for a mixed fleet of ground and aerial vehicles is highly desireable for mixed fleet work.
  • What is an example of a minimum set of messages?
    • The GSoC project I am doing does a few basic things that could be a start
      • Localization data from Cartographer - Using vision or LiDAR based localization on the ROS computer that’s not possible on the embedded system is very common for GPS denied operation
      • Position, velocity, and acceleration reporting from the autopilot to the ROS computer. We already have merged this in ArduPilot for both ground and aerial vehicles.
      • Velocity control from a navigation stack like NAV2 - yes, there are update rate problems doing low level control with out-of-the box Ubuntu systems like a Pi running Ubuntu 22.04, however there are plenty of platforms that can run ROS 2 in realtime. I’m currently working with Steve on this: Switch from Twist to TwistStamped for cmd_vel · Issue #1594 · ros-planning/navigation2 · GitHub
      • Agree with Jaeyoung - It would be great to define an alternative to trajectory control for how a high level planner controls the drone, but I don’t know if there’s any that are already adopted
  • Starting from scratch or re-using REP-147?
    • I’m happy to just revise REP-147. I think a lot of really great info and context with respect to MavLink is there, and since MavLink is still used, it’s relevant. That said, some of the information is incorrect. ArduPilot’s controls are done in the inertial frame, not body frame, so it makes sense to allow ROS users to do control in the inertial frame or body frame depending on what they set for the frame ID. If the autopilot supports a ROS interface for both, the computation to the desired control frame can happen in the autopilot at real-time, and it’s just a transform, so I don’t see there being concerns. The ROS computer can then just control in whatever frame their controller prefers to operate in.
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