I haven't started flying yet, but I've had a GH2 for a couple years, and it's the one I plan to fly. I don't think I'll run into the weight issues so much, but just wondering if anyone has any experience with 2-axis gimbal, radians, red rings, balancing, etc... all for a GH2? Aloha, Jon
We use Wookong and I think our gains are around 150 in wkm. It's been a while since I've looked so I can be wrong. When the Radians came out everyone was very hush hush about their settings and it's nice to see more and more are helping. We recently changed our Radian settings to a lot higher. I don't know what they are off hand because the copter doesn't live with me. Tilt/Roll are in the 120's to 160's. The huge thing about the bouncing/twitches are balancing. They don't really stress that enough or even show you how. The lighter cameras need to be raised higher than the tilt bar lets you... unless you have the new new adjustable tilt bar. But before you go out and pay $100 for it... try using spacers on the camera mount. You may have to changed the way it screws into place but having the camera mount up 12mm to 18mm lets you get the CG for the tilt better. We sometimes use a Canon T2i which is lighter than the 5D and have used this and it works great. I believe that Quadrocopter has a video on balancing but you'll want to watch it a lot so you can fully understand it and how important it is. I zip tied an extra boom to the star plate and "hung it" sideways to check the pan balance too. It better than hanging your whole copter by it's boom. Less strain and easier to work with. Secondly... after balancing.... I decided to pick it up the gimbal unattached to the copter and use it like it's the MoVi using that same boom I zip tied to it. Move it on the roll axis. If it's not holding horizon... up the gains. And repeat for the other axis. The pan isn't perfect but the other axis are better than they have ever been. It's beats changing gains.... flying... landing... checking your footage... changing gains again... flying... I think you get it. It's a fast easy Trial and Error but it all starts with balancing.
Brandon there is a complete set of videos at http://www.youtube.com/user/FreeFlySystems on how to balance. That's in addition to the videos at QC and others like Drone4You. Really liked the Freerunning video. The BTS with the camera car was certainly interesting.
I also zip tie a boom to the star plate to "hand fly" the gimbal so that I can train camera operators by walking up and down the room past a "target" on the floor, and by ascending and descending, doing "fly overs" etc. By using the payload camera video fed into a large screen TV, both the operator and I can assess the video. Not only is this a great, low stress way to train a camera operator, but it's also good upper body exercise for the pilot! AMHIK. Andy.
Hey Andy, or whomever. I'm just re-doing everything now, and I'm wondering about a quick how to on balancing the tilt axis. Is there a proper order (roll, then tilt?), Is it just a matter of finding the right horizontal spot for the camera where it's not flopping around? I have watched all of Tabb's videos again and again. I'm pretty good at the roll axis, but not quite there on the tilt.
Andrew: In do the balancing in increasing order of "mass in motion," so tilt first, then roll, then pan. The real trick is, for any given camera, to figure out where the cameras center of gravity is with respect to the axis you're currently trying to balance. For tilt, you then need to move the camera fore and aft until that C of G is in line with the tilt axis -- and by "in line" you have to both be in the correct fore/aft position but also in the correct up/down position. Too far forward: Camera will flop forward (take the belt off to assess this, of course). Too far backward: Camera will flow backward. When you've got it in the neutral point (where it sits and thinks about what it's going to do for a moment) then you can worry about the C of G in terms of above/below the tilt axis (the axis about which the tilt mechanism moves -- there are steel rods about which the movement occurs). If the camera's C of G is too far above the tilt axis, the camera will topple either forwards or backwards if you displace it from horizontal. Too far below, camera will behave like a pendulum and return to the central position. Stop and ponder this point -- once you "get it" then camera/gimbal balancing snaps into clarity.... When you hit the "Goldilocks" spot (where it's just right), the camera will stay put in tilt regardless of where you position it. Then worry about the roll axis -- you may have to cant the side tubes up (so the leading end is higher than the trailing end) to lift the C of G up into line with the roll axis pivot point -- again that axis is the bearing on the big roll pulley. Same deal (take the roll belt off): Camera/tilt part of the gimbal's C of G too far below roll axis: camera will pendulum back in roll to the to central position. Too far above: camera will flop left or right in roll. Once you've got both tilt and roll balanced (and you may have to go back and tweak the tilt axis, then the roll axis). If you think you'll never get the damn thing balanced, the recommended procedure is either a beer, wine, or stiff single malt whisky. But once your mental model includes the above you can pretty quickly balance any camera. Once you have tilt and roll done put the tilt and roll belts back on and then rotate the Cinestar so that the booms are vertical, and you can go about balancing pan. The adjustment there to move the vertical post on which the roll servo is mounted either towards the center of the hub or away from it. Again, take the belts off so you're not fighting the servo (or vice versa). Hope that helps. It took me an evening to get my head around it. That and a couple of glasses of good Oregon pinot noir. Andy.