Your Radian gains?

Discussion in 'Radian' started by Brad Meier, Sep 19, 2012.

  1. Brad Meier

    Brad Meier Active Member
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    So I mounted my 7d and hefty lens that I have been flying with previous. Its all been re-balanced perfectly without the belts. To get the gittering to stop I had to turn the gains way down.. Yaw and Tilt are both down around 70 while roll I was able to keep up around 120-130. It seems that when I move the whole setup its floating around level but not super locked on... I would guess because of my low gains. Also, the Yaw axis is moving to the right at about 360 deg in 4 min while hanging here. I assume there are settings to keep that locked on... or is that a function of gain also? My servos are all 3 freefly with prob an hr flight time.

    I have also noticed in the diagnostic window that the SBUS box is checked even though I am running a DX-8 with the Spektrum satellite. Clicking on the Spektrum box does nothing. My system is setup exactly like the photo in the manual for Spektrum.
     
  2. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Brad, those gains seem reasonable to me. They are not particularly low. One point to note is you need to initialize the gimbal sitting firmly on the ground and then hang it for tuning the yaw. If you initialize with it swinging in the air the gyros will not get a good initialization and you can get excessive drift in the pan axis.

    When you say that S.BUS box is checked, are you talking about the pan module or the tilt and roll? I think the Pan should say Spektrum while the others might say SBUS as we use SBUS to communicate between the modules.

    Best,

    Tabb
     
  3. Brad Meier

    Brad Meier Active Member
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    Right on both accounts... Any reason why I was able to get the roll gain so much higher?
     
  4. Tabb Firchau

    Tabb Firchau Administrator
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    one word INERTIA

    Glad you got it working! ;)

    Tabb
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Plus a bit of MOMENTUM? ;)

    Andy.
     
  6. Philipp Goose

    Philipp Goose Member

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    Hi Guy´s,
    i think it will be helpful for other Radian users to knew what thair Gain settings with which Gimbal!

    I use 3 Axis Cinestar

    Tilt 220
    Roll 130
    Pan 80


    greets from Germany
     
  7. Brad Meier

    Brad Meier Active Member
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    Thanks Andy.

    I have a 7d with a 16-35L that I flew all day today. Terrible results. Flying was smooth but the roll and tilt jittered worse than with the old FC2.1 controlling stabilization. Im beginning to think my gains are too low. Tilt was at 55% and Roll 130%. Is anyone running a CS8 360 with a 5D or 7D that can share their gains?
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    WIth a 5D Mk III, Epic tilt bars, and 200mm side booms, I've been bench-testing and found tilt 110% and roll 125% *seem* stable. I'm a little concerned that, by watching the HDMI video downlink, that the tilt might not be responsive enough, so I was planning to do some additional testing after I've pan-balanced the gimbal and set the pan gain with the C8 suspended by the battery plate (after it's initialized on the table).

    Andy.
     
  9. Brad Meier

    Brad Meier Active Member
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    I boosted my tilt to 120% and left roll at 130%. Ill see how that goes tomorrow. I have standard tilt bars and side booms. Everything balanced. Im also thinking that vibration may be translating through the frame to the 360 mount. The O rings seem to be increasing the vibration vs dampening it.

    Brad
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    What's the air temp where you're flying? I've heard tell that when the temperature gets cooler/cold that folks take a few O-rings out of the vibration isolations. I'm not sure what the temp/number-to-remove graph would look like though.

    Andy.
     
  11. Brad Meier

    Brad Meier Active Member
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    75-85F. So maybe that's not the problem
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Nice temperatures (presuming the humidity percentage is NOT close to the same numbers!)

    Any chance with all the balancing foreplay that you need to tighten up the servo/pulley belts? I found that I had some play in all of them -- I could grab the servo pulley wheel in my hand and gently waggle the large pulley wheel and there was some movement in the large pulley not transmitted to the servo pulley -- same with the "star wheel" gimbal mounting plate and the pan servo. It seems like the belts should only displace about 3 - 4 mm at the mid-point between servo pulley and big pulley if you push them with your finger.

    Tabb: is this the recommended tightness?

    Andy.
     
  13. Philipp Goose

    Philipp Goose Member

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    The Topic of the o-Rings is also interesting.


    We us Canon 5d GH2 and CX730/ in USA CX760 and we have 4 of 6 Rings inside the Frame (CS 360°).
    Actual is in Germany 15-20 Celsius

    Who many Rings are U using?
     
  14. Wing Gee

    Wing Gee New Member

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    I've been testing my units with a go pro, and I originally had my Tilt gain set to 100% and roll gain at 80% I was still getting wobbles on the roll. I increased the gain to 150% and it's a lot smoother now and it's starting to get that "look". I'm going to raise it some more and give that a try.

    Originally before mounting the 3 axis gimbal, I had the roll gain set to 220%. It looked good when moving it around by hand, but once I mounted it to my hexa and hanged the entire rig from a rope, The roll axis would find a resonant frequency and it would wobble like crazy. I started over and decided to try and tune it in flight instead. Then judge the results from the video taken. I'm getting there, but no where near perfect yet.

    I'm also starting to think, that part of my problem is the lack of weight on the gimbal. The gopro is really light, and not sure if the wobbling i'm seeing is from the lack of inertia.
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    As I understand it from Tabb and personal experience, the gain setting varies depending on the mass in motion. Different cameras, gimbals, and framesets will therefore all require different gains. You certainly cannot set pan gain unless you let the Radians initialize on the ground/table and then suspend the frameset by the battery plate (or fly).

    Try doing a "binary chop" on the gains -- if you're currently at, say, 220, then half it to 110 and test. If it's OK, but a bit sluggish to track, go up half of what you came down, say up 55 -- if that's too much then come down 25 (or 27 if you prefer mathematical accuracy). If you creep up or down a few percent at a time I found it quite hard to see the difference and therefore to determine the optimal value. That could, of course, be "operator error." ;)

    Andy.
     
  16. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Andy,
    this is the same way I test mine... Im needing to move all my radians to their new "retail" locations and then test everything... again... Sucky part is im in Denver all this week so I can't do anything till I get back! GRRR

    josh
     
  17. Brad Meier

    Brad Meier Active Member
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    Alright.. I upped the tilt gain to 130% and found it to be much better though still not dialed in. Now I think I'm having an issue with the rubber O rings. The design is great but I feel like the 360 mount plate is bottoming and hitting the bottom of the copter. Also the standoffs may be moving and hitting the carbon around that area. I think to solve this I need less motion from the o rings, longer standoffs, an maybe bigger holes for the standoffs to get through. Thoughts?
     
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  18. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Brad: Are you talking about the 360 mounting plate hitting the bottom of the copter while it's flying (or when you suspend the aircraft by the battery plate so that landing gear are in mid-air)?

    The gimbal certainly will hit (or comes close to hitting) the hub plate if the copter's just sitting on the table -- in flight, the gimbal is suspended by the O-rings so the clearance between the two increases enough that, unless you fly the way I do (and please don't -- you'll scare me), you're unlikely to get the gimbal to impact the bottom of the copter.

    Also, again on the table top, you can certainly deflect the vibration isolators laterally far enough that they will impact the hub plates, but again, you need to fly like to me to make it happen in flight. (Seriously, you need to make an extreme move for it to happen, I think...I've not been able to do it in flight no matter how "well" I fly.)

    So, can you clarify whether your experiments are done with the gimbal resting on the table top or not?

    Andy.
     
  19. Brad Meier

    Brad Meier Active Member
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    All in the air. I had been flying at around 35 mph for about a mile with a car. At those speeds the copter is tilted over at 30-40 degrees which I believe shifts the weight of the 360 towards the lower end of the copter thus moving those standoffs against the carbon and also probably hitting the plate with the bottom of the copter. The flight was very smooth. Im thinking its probably more the standoffs hitting the holes.. so either bigger holes of stiffer O rings to give it less play. Maybe both
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I suspect you're right, Brad -- but you're doing things with the C6/8 I haven't dared do yet. I'll let other smarter than I in this area comment further on what's going on.

    One question for you, though: Do you find, at 30-40 degrees of tilt that you're really having to goose the throttle as the center of lift is now canted over quite far?

    Andy.
     

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