Arducopter 3.2 on APM2.5 -Problem with drone lurching its way between standard waypoints

Posted by Colin Henderson on May 4, 2015 at 2:46pm

I need some advice. concerning tuning out a problem I have with my 800 hex stalling pulling up then continuing forward between way points during standard (no splines) waypoint missions even in no wind conditions.

I have tried reducing the WP Horizontal speed WPNAV_SPEED) and Waypoint Vertical Acceleration (WPNAV_ACCEL) to no effect. I have also tried reducing Rate Roll/Pitch I values by a small amount again with no obvious effect. In short there appears to be many other perimeters to try however some help in the right direction would be most appreciated.

In general the drone handles very well in other modes including loiter and is well trimmed with the correct CofG.

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Replies

  • Scott M Brown May 4, 2015 at 5:21pm

    I have seen this behaviour when using do_digicam commands while flying survey grid missions. The do_digicam command is a waypoint that follows reaching the calculated camera triggering waypoint....

    My $.02

  • Mike Boland May 4, 2015 at 3:20pm

    That sounds typical of having a delay in the waypoint.

    If there is any delay, any, then the copter comes to a complete stop then continues, and that is what your problem sounds like.

    Have you tried saving your waypoint file and looking at it in a text editor to see if there is any value in the delay field?

    • Colin Henderson > Mike Boland May 4, 2015 at 3:29pm

      Hi Mike

      I do have  30s delays at the waypoints for panorama capture. However that's not my problem. My problem is in the transit between waypoints not when it hits one. This is when i'm experiencing the instabilities.

      Many thanks for the quick response.

    • Mike Boland > Colin Henderson May 4, 2015 at 3:41pm

      OK, just reread your post and I see now.

      I have also noticed this when we were doing grid scans, that when it leaves the waypoint it seems to pick up too much speed then backs off. Most noticeable in a tail wind or still conditions but not so noticeable in headwind.

      The slower we made the speed the more noticeable it was, indicating an over acceleration followed by braking.

      It is sort of like take off in any auto mode, an initial thrust off the ground.

      If you increase the speed does it still do it?

    • Colin Henderson > Mike Boland May 5, 2015 at 3:22pm

      Hi Mike

      Yes yes... that sounds exactly like the problem I am experiencing. I will try going the other way and increasing the speed. The other thing I want to try is reducing the acceleration. My drone is quite heavy with the camera payload and builds up quite a bit of momentum when its traveling. If the system is breaking to keep down the speed and having to fight against the forward momentum to due so, that would seem a logical explanation for the behavior although I might have thought reducing the speed of travel would prevent this happening not make it worse. I will try as you suggest increasing the speed and post my results.
      Many thanks
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