Shop OBEX P1 Docs P2 Docs Learn Events
Copter yawing to the left — Parallax Forums

Copter yawing to the left

grayfoxgrayfox Posts: 39
edited 2014-12-18 15:16 in Robotics
So i finally got my elev-8 flying again thanks to Ken and my buddy alex with his awesome 3d printing skills...ill make a post for that later.
However, now that i have my elev-8 in the air again, it seems to yaw to the left ever so slighty. I did a test a few minutes ago....I got it about 50 feet in the air and just let it hover with my hands off the sticks.....and very very slowly it yaws to the left.....about a minute in, its 90 degrees and another minute it will be 180.... I thought that my controller might be screwed a bit since ive been flying my zagi lately....but alas, i had it on the right model and it just wont stay still.......any thoughts out there?
I made sure my trims were centered and i have no subtrim set.

Now, the there are a few slight differences between how it was and how it is now...
i now have the blue motors that you can buy off the Parallax website ( did have the yellowish ones) I did all of the programming and calibrations for each motor...
i used to have the battery mounted under the hoverfly board, but now its mounted dead center on the bottom of the copter.
I used to have the rx on the edge of the airframe on the right side...now i have it velcrowed on the upper rear of the airframe...

Any thoughts???

Comments

  • trangertranger Posts: 179
    edited 2014-11-15 15:28
    Occasionally I'll get a fast yaw rotation on take-off. The only way to fix it is to sit it down, power down and back up. I've also seen the slow yaw rotation. It's slow enough that I either just fly with it or try to trim it out - no big deal.

    I suspect some calibration is required for the gyro. But, without firmware that supports it, it isn't possible.

    Jason Dorie's firmware does have a gyro calibration routine that works with 'ground station' software. I believe the gyro behavior is temperature dependent and the calibration attempts to find what that is. You then plug values into the firmware.

    To get solid yaw stability might require a different control scheme. A gyro is said to provide good short-term information, but requires a long-term sensor to reference. For pitch and roll an accelerometer does the trick. I suppose for yaw, a compass would be needed


    -Russ
  • W9GFOW9GFO Posts: 4,010
    edited 2014-11-15 16:59
    I would carefully check that the balance of the quad is correct. If one motor works harder than the others the torques won't be balanced, which will cause a tendency to yaw.
  • grayfoxgrayfox Posts: 39
    edited 2014-11-16 12:29
    W9GFO: Thanks for the advice. I did try different mounting places of the battery and the rx and it still yaws to the left. I decided to just trim it out. 2-3 click to the right and the problem is gone. Not worried about it anymore if thats all it is. :)
    Thanks
  • stanles78stanles78 Posts: 8
    edited 2014-11-17 18:28
    I just brought quad in from short trip in cold car and it yawed badly (so much that I didn't want to lift off). Arming and disarming issues also. after a few minutes and reboots it worked fine, maybe due to warming up. and a little tip if anyone destroys the flimsy stock landing gear....tennis balls work like magic...especially on smooth indoor surfaces. We can slide it across the floor on edge.
  • grayfoxgrayfox Posts: 39
    edited 2014-11-22 11:20
    yeah i also think its cold air. I flew it in the gym at work and it was just fine. After i charged the battery and flew it outside at home, it yawed the same as it did a few days ago.....
  • trangertranger Posts: 179
    edited 2014-11-23 16:08
    stanles78 wrote: »
    ... a little tip if anyone destroys the flimsy stock landing gear....

    My originals are a little beat up, but are hanging in there pretty well. I also have a set that came with the crash pack. The weak point on these seems to be the 4-40 threads. A longer screw with a nut or a helicoil are options I've considered.

    -Russ
  • JasonDorieJasonDorie Posts: 1,930
    edited 2014-12-02 13:33
    If the quad is changing temperature (ie warming up, or cooling off) a non-calibrated gyro will drift quite a bit. The unit reads whatever the current gyro value is at power-on and treats that as zero. If the temperature changes, the zero point changes with it, so the original zero isn't quite right any more. If you let the board warm or cool to match the surrounding temperature before flying, you'll minimize the effect.

    The QuadX software I wrote has routines that compensate for the temperature drift effect. The numbers are different for every gyro, so you need to calibrate your own machine. It's not a difficult process, but it's not as "plug-and-play" as I'd like it to be.

    Jason
  • mklrobomklrobo Posts: 420
    edited 2014-12-18 15:16
    :) Hello! I have some ideas, myself; having recently bought one. :)

    Looking over the instructions, any vibrations on the copter can interfere
    with the gyros. Having read that, I looked over the copter, and found
    many places mechanical dampling could be used. In industry, they use
    some devices to detect extraneous mechanical vibrations.
    With that, I wonder if a propeller could be used with some transducers
    to detect vibrations that could alter the flight path?
Sign In or Register to comment.