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Gains: understanding, flight testing

Discussion in 'Phantom 1 Help' started by GearLoose, May 25, 2013.

  1. GearLoose

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    tanasit wrote in another thread:

    "The Basic GAIN (first row in the GAIN tab of BASIC section in the Assistant) controls Flight attitude which means the higher the gain, the faster your Phantom will go back to level positions.
    the Attitude GAIN (second row) control stick response which means the higher the GAIN, the faster and more powerful your stick command will be.
    "

    First of all, because the wind has been squirrely here I've done my first flights in our small meadow, which is bordered by trees, ponds and brushy wetlands. It's protected from wind but there isn't much room for mistakes, so I'm flying very very cautiously, trying to get a feel for the controls, etc. The Phantom reacts so quickly that a couple of seconds of pilot confusion can easily put it into a tall tree (or even a pond).

    Hoping to moderate things, I've lowered all of the gains to 80%. Yesterday I finally completed a full flight without a panic attack or a crash (though there were some tense moments!).

    It seems that the lower gain settings are having the desired effect but after reading tanasit's explanation above, I wonder if the Basic gains should be left at the default settting? I'm not clear on what "return to level position" means, at least in terms of keeping the Phantom under tighter control.

    Another thought: would adding a camera or ballast help slow this thing down a bit? I've got 4 batteries so that isn't an issue.

    With any luck the weather will moderate today and I'll be able try a flight nearby in a huge wide open pasture.
     
  2. tanasit

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    RE: I'm not clear on what "return to level position" means,

    In GPS or ATTI mode, jab the stick to any direction and release it right away; with default Basic setting it may take say 0.5 second for the Phantom come back to level (after it responded to the quick stick command earlier). Now if you increase the Basic gain setting (another 30% or more) and repeat the test above, it will now takes like 0.2 seconds with springy action.
    So if you lower the gain, it may take 0.8 seconds with mushy feeling.

    If your Phantom is over weight, those Basic setting will have less effect.

    In windy condition, especially like yours with gust and turbulence, you will NOT get a good feel of the control.
    Wait for a calmer day and try out again.
    Especially now you can set the Gain on the fly using the gadget below:

    http://www.shapeways.com/model/1082710/ ... material=6
     
  3. GearLoose

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    Thanks, tanasit, that is very helpful.

    I made something of breakthrough today by flying in a ten acre pasture with no obstacles. I also added my Drift HD 170 camera for the first time. I assumed that with the camera's weight and the gains at 80% that the Phantom would be quite a bit tamer in flight. This proved to be true, so I was able to make three complete flights without a crash or a panic attack! (I also got a lot of good footage of pasture grass.)

    Once I'm able to consistently maneuver this thing where I want it to go, I'll start increasing the gains.

    Your help is appreciated!
     
  4. Gizmo3000

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    what has me a bit baffled tho is how weight and props come into effect.
    I've heard it's good to bump them all up if you're flying a bit heavy? (or leave Yaw alone?)

    and then I see DSLRpros selling carbon fiber props, .. saying that gains of "Pitch-190 / Roll-190 / Yaw-150 / Vertical-150 (and Attitude Pitch-70 / Roll-70) " are ideal because the props have increased efficiency?

    (http://www.dslrpros.com/Products/tabid/ ... fault.aspx)

    Gains are definitely a bit of voodoo to comprehend,.and test out.
     
  5. tanasit

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    One simple thing to keep in mind is that we like the way our Phantom fly differently.
    At first, I never touch the GAIN setting because I was happy with the stock flight characteristic. Then I started testing different type of props and in particular the carbon fiber ones which caused my Phantom to oscillate. No matter how I set the GAIN, I could NOT get rid of the oscillation: too high setting yielded fast oscillation; too low resulted in swinging like pendulum; somewhere in the middle was unstable. The test took several hours since I had to hook up the computer, change setting, test fly and hook up and change and test fly, etc. I almost concluded that the prop which is 9x5 carbon fiber is unusable but then I remember people using bigger props for heavier Phantom so I attached 2 extra battery packs to my stock Phantom to simulate the weight with video gears. Sure enough, the oscillation disappeared!

    And now we have the ability to change the GAIN in flight with stock TX, why not experiment. Here is my suggestion:

    1. Set X1 for the Basic gain first and do that for all pitch, Roll, Yaw and Vertical. Find the setting where you feel the Phantom is most stable or flight attitude that fit you best. Do not touch the lever, connect to Assistant to get the number readout then set it accordingly and then you can inhibit the Basic.

    2. Now set X1 for Attitude gain for both Pitch & Roll and test fly to see what setting yield the best response to your stick command. I left the X1 for this setting until I found the best for my flying style then I permanently set the X1 for Basic as above. And the reason, I chose to use the lever to set the Basic in stead of the Attitude gain setting because the future flying sessions may be windy or sometime I fly without the video gears or I change to different props, then I will need to change the flight attitude NOT the way my Phantom respond to my stick which I have the preset values that I like already. In the past few days, the wind kicked up pretty good, so I just turn the Gain up so that it is more stable.
     
  6. Gizmo3000

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    Great idea with using the X1 to test out the gains.. I guess I should try that. (I take it that you're using a Futaba or similar witha dial for the X1? right now I have the X1 set to the gimbal.
    getting a new brushless gimbal, so perhaps I'll wait until everything is installed (for final weight/balance) and see how it all works with the different props and gains.

    out of curiosity, what kind of gains did you arrive at with your certain props+weight amounts?
     
  7. GearLoose

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    A few days ago I set all of the gains at 80, hoping to calm the Phantom down for my first flights. I think it was helpful but I also think this caused the Phantom to drift quite a bit in GPS mode. When I tried to get a stable hover for a landing, it would fly drunkenly around in a circle at least twenty feet in diameter.

    In order to try catching/landing the quad according to the suggestions in another thread, today I reset the gains to the default values, 100. Sure enough, it now hovers very obediently in front of me. I made two successful catches but on the third attempt I fumbled the TX. This bumped the switch from GPS to ATTI and goosed the throttle. My heart rate soared even faster than the Phantom.

    By the time I settled down and got it leveled off again, it was indicating a low battery, so I settled for a gentle grass landing.
     
  8. remvideo

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    I've added a good bit of weight to my phantom, and it seems to need more power when taking off, or recovering from my lowering it down, which gain setting(s) should I adjust ?
     
  9. tanasit

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    Increase VERTICAL gain 10% at a time and see if the rapid change in attitude get slower.
    Doing so is like telling NAZA to do the attitude hold faster.
     
  10. remvideo

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    its very sluggish on lift off also, I actually turned yaw down 10% cause I feel it rotates too fast
     
  11. tanasit

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    If you're not using Phantom TX, you may want to set the exponential or dual rate for the yaw and others.
     
  12. remvideo

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    I am using phantom Tx, could you explain what you said ? as if you were speaking to a child :)
     
  13. tanasit

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    Phantom TX is rather simple in term of features so it doesn't have the ability to fine tune the stick command.
    For example, it is also obvious that the Phantom TX has no TRIM buttons.
    As for the exponential and the dual rate, they are the common features of most current TX.
    Exponential is the mathematical term defines the graph with is NOT a straight line.
    A straight line graph represents the relation between the movement of the stick and the movement of the corresponding servo or in this case the YAW control output from NAZA. It is "proportional" for the straight line which mean if you move the stick 20% from neutral position then you get the output 20%; 50% stick away = 50% output; in this case the exponential value = 0.

    But if you want your stick to be LESS sensitive around the neutral, you will want NEGATIVE exponential setting (some TX use + but few). For example if you set your YAW stick with -30% exponential, then if you move the stick say 20% from the neutral position, you will get LESS output like 10%. Most people will use this setup for more stable around the center stick because you can move the stick about the neutral MORE than usual and still get nice and smooth control.

    Dual rate is similar but deal with the end points or sometime they call it TRAVEL which means how much the servo travels at the maximum of the stick input. LOW rate say 80% will give the maximum of output at only 80% vs HIGH rate 100% (some TX gives 125% or more) gives maximum effect. So if you set this dual rate, you will have 2 postilion switch that you can flip and summon the rate that you want to use; for full aerobatic you will require the full control so the HIGH rate is used but for precision and videography you may want the LOW rate for nice and smooth transition without jerkiness and such.

    Note: once the exponential is set, you can't turn it off in flight unlike the dual rate which is switch controlled.
    Both Exp and D/R can be used together for optimum effects.

    Note 2: the Attitude Gain setting for Pitch & Roll has the same effect as if both Exp & D/R are used. IF you set the HIGHER % Gain, the stick control (movement) will have MORE effect to the Pitch & Roll of the Phantom. In another words if you want your Phantom to be sensitive to the stick, then increase the Attitude gain setting but if you want your Phantom to be easier to hover smoothly and feel somewhat mushy then lower the gain. However you may not be able to feel or see the differences between different gain setting if you use your computer to set the Gain, then go fly because the change will be very minimal until the change is large enough. So the best way to go about this is the use the Shapeways control arm(as mentioned in the second post) so that you can change the Gain "in flight".