Copter 4.2.x can't accept DO_CHANGE_SPEED in auto mission

@rmackay9 Thanks for the reply. That makes sense, please also note that in our case, sometimes the mission speed is excepted and sometime snot! that’s been the confusing part. We use both Solex and QGC, the waypoints speed in RC QGC are correct too, so its the Pixhwk that’s that following the syntax (Im assuming) PS We’re using Herelink system


OK, so the issue with do-change-speed is that it must appear after the first waypoint command. I guess this is discussed above already but in any case, it is on the list to fix, sorry for the troubles!

1 Like

Is this really a problem though? With a DO_CHANGE_SPEED command it will run at that speed until another change speed command is issued. So set the WPNAV_SPEED at what you want to run until WP1 then set speed commands as you like after that. Perhaps there is a use case I’m not considering?

Maybe this is that use case:

  • User sets WPNAV_SPEED to a default, somewhat slow speed for survey or sprayer missions.
  • Vehicle runs out of battery and executes a mid-mission RTL.
  • User makes a slight modification to the mission to resume in the middle and sets a faster travel speed via DO_CHANGE_SPEED after takeoff followed by another DO_CHANGE_SPEED as the pattern is resumed.
  • Faster speed is not accepted and user loses valuable flight time to slow speed.
1 Like

Ah OK. Resume a mission at speed from take-off. That makes sense.

The point is, it doesn’t obey any or rather randomly obeys the Do_Speed change
For our case we rarely fly faster than 2ms (boring I know lol) so changing the settings for WPNAV_Speed to 2ms might override to a default. Our issue is that because the speed set via simple grid, which is set to 2 is ignored. As soon as we start a mission. Which is only WPs and an Alt (we arm and loiter to a rough closer location before auto) once in auto the drones takes of at 15ms! And we’re only 2m alt so that’s scary! :scream:

I’m not following why that would be the case.


If WPNAV_SPEED is set to 200 (2m/s) then that’s the speed it will start at when it begins the mission. Any DO_CHANGE_SPEED commands after that should take effect.

It’s not random really…

Maybe provide a log of a scary case. I of course believe you but it doesn’t quite match with what I think AP’s behaviour is.

1 Like