Fly first time with 3 axis gimbal

Discussion in 'Cinestar 8' started by Dave King, Mar 11, 2013.

  1. Dave King

    Dave King Well-Known Member

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    It's a good day when you can go home in one piece and things work out like they should (for the most part). I just stuck a Gro Pro 3 on the camera gimbal and put it in stabilization mode (no slew) and reduced the gains to 75% for roll and nick, and 40% for pan. I didn't have an extra camera operator per say as I just wanted to see what happened it mode 2 - stabilization no slew.

    Here's all the changes since the 1st time out in January
    1. Added 3 axis gimbal and radians. I Flew last with no camera gimbal just landing gear.
    2. Added FPV camera
    3. Installed new flight control board.
    4. Flew with 2 batteries instead of 1
    5. Balanced the copter suspended to the ceiling at my house
    6. Balanced the gimbal suspended to the ceiling at my house
    7. Checked balance with gimbal on the copter in the air.
    8. Balanced the motors with cold shoe mount and hot shoe bubble level.

    I brought 4 batteries, I was planning on using 2 QC 8000's in parallel but I forgot to sync charge them and I didn't want to fly with just one battery. So I used 2 QC 6200's in parallel which gave me about 12-13 minutes flight time. The Go Pro battery only lasted 5 minutes on a fully charged battery. I even cycled it completely dead and then charged it full.

    I flew with all MK settings at the stock factory settings except for ACC gyrocomp I put at 50. The copter is very smooth overall, but it does tend to lose altitude a little bit and wants to descend unexpectedly. Can anyone recommend an adjustment to compensate for this?

    I didn't even use my downlink feed at all, I was completely looking at the copter and using the navigation lights for orientation. I'm very pleased with the light I have on boom 5 as I can see it 200 yards a way no problem. I'm thinking about putting an extra 8mm blinking LED in the boom right about the 12 LED cluster.

    GPX files look good no errors, I do have IC Counter errors but they are there from the first log point to the last and they do not go up at all during flight.

    I ran in manual mode for the most part, never used altitude hold and carefree and engine kill switch were disabled.

    One tip I can give everyone is that if you have not balanced your copter suspended in the air you really need to. You will not believe the sensitivity of the CG when your batteries move just 1/8 of an inch in either direction. What I am doing is purchasing a couple extra battery plates, and prebalancing the batteries to the plates before I go out and then just switch out the plates when I need to switch out the batteries.

    So instead of me trying to reinvent the wheel with the go pro I'm purchasing a Sony 760 and going to work on radian settings with that camera.

    Here's the video
     
  2. Dave King

    Dave King Well-Known Member

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    Can anyone give me any recommendations on smoothing out the altitude drop in the video above? I'm thinking about starting with Gyro D and incrementing it in steps of two at a time. Anyone assign Gyro's to a poti to a graupner knob before?
     
  3. Gary Haynes

    Gary Haynes Administrator
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    Dave here's my settings. Rock solid on altitude hold and I think all of these are standard. Do you have the foam/something over the pressure sensor? How are you controlling after AH is turned on (Stick neutral point)? With or without the spring?
     

    Attached Files:

  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Just from watching the video briefly, Dave, it sounds like the motors are slowing down when the copter loses altitude. You can probably confirm this more readily than I can watching the video.

    If this is the case, can you try altitude hold? If you are flying manually, you may have discovered what are called PIOs. Pilot Induced Oscillations -- that is, if you see the copter climbing you may subconsciously be throttling back, inadvertently overshooting and throttling back too much, the correcting (or perhaps slightly overcorrecting)....

    See if AH will hold the copter steady.

    Also use MK GPXTOOL to look at your GPX file for the flight. You can play back the flight data on an On Screen Display while simultaneously viewing what you were doing with the control sticks -- that will allow you to see if you are indeed causing PIOs.

    Andy.
     
  5. Dave King

    Dave King Well-Known Member

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    HI Andy

    Thanks, yes the motors are slowing down. I reference it to like a car in park with a bad idle. I know this really isn't a huge issue but it does have some variations on it that I would like to smooth out. In the video you see I am not in Altitude hold, but in a couple different places in another flight that day I did have AH on it the copter dropped, I was thinking that the minimum gas setting needs to be raised in AH.

    One question I have about the GPXTOOL feature with on screen display, how do I sync up the video if the video starts before the copter takes off? Do I simply make a cut in the video to where it starts when the copter takes off?
     
  6. Dave King

    Dave King Well-Known Member

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    Gary thanks. I have velcro on the pressure sensor. When I turn on AH, I just adjust the gas and try to get it the neutral point. I am not using the spring. When I turn on AH it seems to drop suddenly and I have to give it gas for it stabilize but to be honest I am not sure where my stick settings are.
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The OSD feature allows you to play the video and mark the start sync point and the end sync point.

    Andy.
     
  8. Dave King

    Dave King Well-Known Member

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    OK, thanks looking at it now.
     
  9. Gary Haynes

    Gary Haynes Administrator
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    Dave if you aren't using the 127 Automatic and have a value of 0 in that field then the copter should hold altitude at the current throttle setting. If you have 127 in the field then after engaging AH you need to move the throttle to the center position. You can check for center by looking at the servo display window in the Graupner menu and make sure you are at the 0 point.

    So what setting do you have for the MKTool altitude setup for Stick Neutral Point?
     
  10. Dave King

    Dave King Well-Known Member

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    127 automatic. So I think I understand the problem when I engage it in AH that it drops or goes high. I'll change it to 0 in the settings. Now I just gotta figure out why altitude is dropping out of AH.
     
  11. Gary Haynes

    Gary Haynes Administrator
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    It probably won't drop after making that change. With 127 set if your throttle when you turned on AH was above 127 it would climb and if it is below 127 then it would descend. If it doesn't hold level when you switch on and are not moving the throttle then something else is wrong.
     
  12. Dave King

    Dave King Well-Known Member

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    Really? Even when not in AH?
     
  13. Gary Haynes

    Gary Haynes Administrator
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    Throttle controls everything if you are not in AH. I am talking about AH being turned on. Again, Stick Neutral set to Zero, throttle at whatever point causes the ship to maintain altitude (hover or moving, doesn't matter), turn on AH and let go of the throttle stick (assumes you have some friction turned on to hold it in position) and the copter should maintain that altitude plus/minus a little bit.

    If it doesn't do that then there are other issues.
     
  14. Dave King

    Dave King Well-Known Member

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    thanks!
    Thanks!
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The real point is that, as Gary says, when AH is on, the throttle no longer acts as a throttle as such -- it acts as a "change altitude control." So above center means go up, below center means go down. The amount above or below center determines the ascent or descent rate.

    Andy.
     
  16. Dave King

    Dave King Well-Known Member

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    Andy or Gary

    I'm trying to get the video to work with the OSD. I opened the video, hit the start and end sync buttons andhit play sync start. It plays the video as I set the start point but none of the telemetry is moving on the screen. I have the GPX file open that goes with the video but I can't get the telemetry to change per the GPX file.
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I found a bug in the current version of MK_GPXTOOL. If you use the File > Open GPX file mechanism for opening the GPX file it will not synchronize. If, however you use the folder structure you find on the MicroSD Card:

    Log (folder)
    Date (folder)​
    GPX (folder)​
    GPS00000.GPX​

    And open the file using the folder navigation scheme you see on the left hand side of the screen, then the video sync works fine.

    Thanks
    Andy.
     
  18. MIke Magee

    MIke Magee Active Member

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    Since we are in the AH domain, has anyone noticed that if you land with AH on, or for some reason switch it on post landing but before motor stop (Thanks Mr. Lanyard), that moving the Left Stick left does not stop the motors, or is it just me? Part of my pre and post landing checks are now for AH and GPS off.
    -m
     
  19. Dave King

    Dave King Well-Known Member

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    Thanks worked like a charm!!!
     
  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Wow. If that is true, please let me know. I'll email Holger because that is another "fail live" situation. Mind you, landing with AH can be "colorful" -- the word "yo-yo" comes to mind. AMHIK.

    Andy.
     

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