WAYPOINTS represented in the local frame

Posted by Baden Corr on August 24, 2015 at 3:23am

Hi,

Is it or is it not possible to set a waypoint that is represented in the local frame? (for use with missions in auto mode) 

I need to have them represented in the local frame as i will not have GPS position. 

I am using a Pixhawk with the current PX4 firmware. 

When i set the messages in Qgroundcontrol's 'plan' tab, it doesn't allow me to transmit Locally referenced waypoints to the flight controller (only globally referenced).

Thanks for any assistance.

Baden

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Tags: frame, mission, waypoints
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Replies

  • Baden Corr August 28, 2015 at 1:04am

    Further on my issues; I have come to the conclusion that i'm struggling to get a solid grounding on which Common MAVLink messages can be implemented on a Pixhawk running PX4 Firmware.

    Is there a list of MAVLink messages that are currently supported by the PX4 firmware? (stable and beta versions).

    As discussed, i am interested in commanding the pixhawk to travel indoors with local frame referenced 'waypoints'. (not necessarily in a mission/auto mode, but could also be in a guided mode!)

    Again, thanks for any help! Cheers!

  • Dale Greer August 26, 2015 at 9:41pm

    I've been thinking about this too. The problem is a waypoint file stores the points as absolute coordinates, except for the altitude, which is relative to the take off point.

    So the easiest thing would be to add a plugin to Mission Planner that would save a waypoint set in an intermediate file containing relative movements. Then you would move the map to the place you intended to fly and load the intermediate file. The waypoints would appear as a graphic overlay following your cursor with the home point at the cursor point, then when you have the set in the place you want, click the mouse, and it would set the points. Then you'd save these points as an actual waypoint file, and load them to your UAV.

    To do it on the Pixhawk would require adding new modes to the waypoint protocol, and a bit of modification to the Pixhawk software.

    • Baden Corr > Dale Greer August 26, 2015 at 9:57pm

      Ok thanks for that! I figure the waypoint protocol doesnt support the local frame so i have decided to look into the guided mode approach. (http://dev.ardupilot.com/wiki/copter-commands-in-guided-mode/)

      Have you tried this mode and these commands before?

      I plan to send a SET_POSITION_TARGET_LOCAL_NED to the drone (obviously using a waypoint the is represented in the local frame). would this work? (I have tried with px4 firmware and failed; however it seems in the APM documentation that it is supported??)

      Additionally i am planning to use a PX4Flow OFS to localise the drone indoors, does the current APM firmware support the PX4Flow to get the drones local position?

      Cheers!

      Baden.

    • Dale Greer > Baden Corr August 27, 2015 at 2:26pm

      I haven't tried that local ned mode before, it looks like it ought to work. I'll have to investigate that.

      And I have a PX4Flow somewhere in DHL land, on its way to my door, so I don't know much about that yet either.

  • Baden Corr August 24, 2015 at 7:46pm

    It appears that the current PX4 firmware doesn't support locally represented waypoints -> https://pixhawk.org/users/start

    Has anyone determined a way around this??

    I am thinking there should be a command out there that can send a location in 3d space to which the drone is asked to fly to?? - I have yet to find the right one!

    Thanks

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