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[solved] Erratic, unreliable waypoint flights!

Discussion in 'DJI Ground Station' started by GearLoose, Jun 15, 2014.

  1. GearLoose

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    As I've described in an earlier post my first waypoint flights were not satisfactory. I thought the problem was poor GPS coverage and a too-cramped set of waypoints but now I'm experiencing the same problem on a much larger scale, to the extent that I cannot trust the GS to send the Phantom safely beyond easy visual range.

    In the video you'll see the problem behavior: after reaching 90' at the first waypoint the Phantom goes a short distance to WP2, where it should hover for 3 seconds, do a stop & turn, then proceed in the same direction to WP3, about 450' away. At WP3, the same settings as all the waypoints: 90', 3 sec hover, stop & turn, 8 mph.

    At WP3, however, the quad wallows around and then appeared to be headed straight into the trees. I'm not sure if this was just another attempt at toilet-bowling but I didn't want to find out the hard way, so I took over control and pulled away from the trees. If it had gone well the Phantom would have turned 90 degrees to the left, toward the center of the wetlands, flown a short distance to WP4, then turned and headed home.

    According to the iPad GPS satellite app, we had 10 or even 11 GPS satellites. (I think the GS showed 10 but I didn't check that closely.)

    Any thoughts on what could be causing this?

    By the way, after landing I immediately sent the Phantom out to a single waypoint, a simple stop & turn and return to WP2. It looked as if it behaved but the flight was only about 300' round trip.

    https://vimeo.com/98267084
     
  2. zenith

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  3. EMCSQUAR

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    Re: Erratic, unreliable waypoint flights!

    Carl, try using another turn method instead of "stop & turn". Try the same route using adaptive turn.
     
  4. GearLoose

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    [Solved!]: Erratic, unreliable waypoint flights!

    I apologize for not updating this thread sooner but my problem has been resolved. My recent waypoint flights have been great successes.

    It was suggested elsewhere that I adjust the compass on my Phantom 1.5 to compensate for magnetic declination. I did this very easily by simply loosening the screws on the compass and repositioning it to point 16 degrees to the right. Then, a compass dance.

    Voila... the quad now flies a near perfect track, behaves properly at waypoints and holds an excellent hover.

    So simple, so crucial!

    http://magnetic-declination.com
     
  5. GearLoose

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    EMC, your suggestion to try adaptive turns put the frosting on the cake. I just made two test flights, one a zigzag pattern, the other a long run over the wetlands and a two-waypoint turn at the far end. The video from both flights is smooth and steady, quite an improvement over the stop&turn flights. Also, the total mission time is much less, which obviously makes longer range flights less risky.

    thanks again!
     
  6. OI Photography

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    Out of curiosity, what turn mode were your missions using before you set it to adaptive? Some of the symptoms you saw sounded like it might have been in bank turn mode on a few of the waypoints. In bank turn mode, the aircraft will overshoot the waypoint and then correct to return to the path to the following waypoint.
     
  7. GearLoose

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    Yes, OI, I was using bank-turn. It seems that the compass declination error and bank-turn were a near deadly combination. The Phantom would wander around a waypoint as if looking for an exit, then head off in an unpredictable direction. I had to fly with the S2 switch between my fingers and very nearly lost her in very tall trees.

    After correcting the compass I have used bank-turn successfully but for my immediate project, which is filming the route of a salmon stream restoration, adaptive turns seem much better.

    Have you tried this: fly to a distant waypoint, regain control manually in order to turn the quad for photos, then restore GS control and continue autonomously? I assume this can be done but haven't yet tried it.

    Also... is there a way to set a mission as a series of several waypoints that that will be flown like this: Outbound, wp 1, 2, 3, 4, 5, etc. Turn at the last waypoint and return inbound, 5-4-3-2-1?
     
  8. OI Photography

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    Right on, that all adds up then, and I'm glad it's all sorted out for you.

    Yes, you can easily pause and resume the mission at will. As for creating the return path you described, the only way I know how to do that would be to create waypoint 6 at the same point as 4, waypoint 7 at the same point as 3, etc. I thought it might be possible to copy or duplicate existing waypoints but I don't immediately see a way to do that.