Position hold performance

Discussion in 'ALTA' started by Rory Hinds, Sep 22, 2015.

  1. Rory Hinds

    Rory Hinds Member

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    I'm really not getting good performance from position hold, so much so that I feel its unusable in movement flight.

    What I'm seeing is the ALTA is super slow, you give a forward command and its like its stoned. Its starts to fly forward then rocks backwards and moves at a very slow pace. Like its been held back.

    You fly forward and it rocks back, being held back and keeps rocking back and forth in flight, so isn't smooth at all.

    Anyone know what settings I need to change to get decent Position hold flights?
    At the moment the only thing its good for is hovering in one spot as I can see the GPS is rock solid, just don't know what the crappy flight characteristics are all about.
     
  2. Rory Hinds

    Rory Hinds Member

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    I'm getting a rocking effect when flying in Position Hold.
    I fly forward full stick and hold it there but the Alta rocks back as if I've taken my finger off the stick.
    This can't be how it's meant to be as its really unstable.
     
  3. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Did you map the velocity clamping controls? Sounds like the velocity clamp is set low. I have mine on two POTs on my Tx and can control the max speed using that.
     
  4. Rory Hinds

    Rory Hinds Member

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    Yes I have the Velocity Clamps all the way up to max on my Futaba 14CG.

    How do I get rid of this rocking back and forth on directional flight?
     
  5. Tabb Firchau

    Tabb Firchau Administrator
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    What are your position settings?
     
  6. Rory Hinds

    Rory Hinds Member

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    Thanks for looking at this Tabb.

    Here are my settings...

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  7. Chris Fanning

    Chris Fanning Member

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    I'm experiencing the same issues. Seems to fly pretty well in attitude mode but in position it's very slow and waddles back and forth. Velocity clamps are turned all the way up. It only does this when Movi is attached. When under no payload it still flys slow in position mode, but doesn't waddle.
     
  8. Rory Hinds

    Rory Hinds Member

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    I'm not sure how to remove this waddle as its destroys the smooth shot. Seems so strange that flying in Height and Manual gives silky smooth and Position modes screws up so much... its the same machine with the same payload after all.

    It would be great if FreeFly can remove the speed restriction. The Max 12 on GPS Speed is just way to restrictive and it would be great to have the option to remove the range limitation.
     
  9. Derek Cooper

    Derek Cooper Active Member

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    Curious - is position hold what would be called GPS hold on other rigs?
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Derek: Yeah. P-GPS on DJI, PH on MK. Don't know about 3DR kit.

    Andy.
     
  11. Gary Haynes

    Gary Haynes Administrator
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    So I see a couple of things you may want to adjust. GPS Angle default is 30. Not sure why it is set so high.
    Vertical Stiffness is low compared to default of 20. Yaw stiffness is below the default 100. It might be worth going back to the defaults.

    How did it fly with all of the default settings? While the GPS speed and climb might be low you have increased them which would be the correct thing to do.

    Tabb will probably have some additional comments.
     
  12. georgemcnabb

    georgemcnabb Member

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    I definitely have the same situation! Flying a much lighter setup than yours through.

    Manual mode it's super smooth position it's what I would call wishy washy, doesn't feel planted right away.

    I haven't touched any settings from out the box. Will have a bit more of a play and see how I get on!
     
  13. Steve Maller

    Steve Maller UAV Grief Counselor

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    I have found that after fiddling with the ALTA's settings and screwing it up a bit, I'm always surprised at how much better it is when I just re-set everything to factory defaults. My velocity clamping works great in both horizontal and vertical. But I will admit that I have gotten confused a few times and flipped them in my mind.
     
  14. Brad Meier

    Brad Meier Active Member
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    The "waddling" effect is caused by the GPS trying to maintain an accurate position and speed. If you are full stick at 12m/s, the Synapse will maintain that 12m/s very precisely correcting for wind, etc constantly. The waddling will be most noticeable if you suddenly command from 0m/s to 12m/s. The Synapse first tries to accelerate to 12m/s by pitching over to a large angle then will back off once reaching 12m/s... and also correcting for wind. Its constantly correcting... Think very accurate

    Think of height hold and position modes as a tool for getting precise, controlled moves (think dolly in the sky) where you need to maintain an accurate motion either horizontally or vertically. My max GPS speed is normally set at 8m/s or less. If I need to do a fast move, I do it in manual mode... Id say I fly 95% in manual mode.

    You can adjust the Position->Hold Strength to lessen the waddling effect but your effectively reducing the accuracy of the positioning.
     
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  15. Chris Fanning

    Chris Fanning Member

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    Guys I appreciate the response and help, but there is nothing normal or accurate about what mine is doing. It rocks back and forth by about 10-12 inches on the forward and back axis at a medium tempo constantly when in position mode under full payload in forward flight. Does not do this in height hold. I'm sure it's just a setting to adjust but it's very unstable like this. I happen to be going to freefly tomorrow so hopefully can get an answer to this.
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Chris:
    Please post again after your visit to FF -- I think there will several forum members who would like to hear what you find out.
    Andy.
     
  17. Chris Fanning

    Chris Fanning Member

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  18. Chris Jordan

    Chris Jordan Member

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    Screen Shot 2015-09-24 at 1.46.49 PM.png
    The SB told us to change VS to 12 from 20... Is this not the case anymore Gary?
     
  19. Chris Fanning

    Chris Fanning Member

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    I haven't changed any of my settings since receiving the Alta. It's all set to default. Chris where did you get that service bulletin? I never received that one.
     
  20. Gary Haynes

    Gary Haynes Administrator
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    You are correct on the 12 value I was looking at. The Rev B manual and forgot about the SB
     

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