I just upgraded to the three axis gimbal and I'm trying to get the pan radian set-up. It oscillates no mater how far I turn the gain down. The axis is perfectly balanced. I initialize the radians on the bench, then hang the c8 for testing. I'm using a dx-8 for the camera operator. I have both the spektrum satellite receiver and a graupner rx connected for speedy transition to single op. Here's a video: The gain settings drop from 60-40-20 in the sequence. Any suggestions on what I'm doing wrong? Thanks - Nick
It almost looks like it's catching or it isn't panning smoothly because of the tension on the pan servo and belt. How well does it turn if you are just using your hand to turn it? Josh
How much play do you have in the pan belt? There should be about 2-3mm of deflection on the belt when you push on it between the servo and the pulley. Josh
I'm also wondering if it has something to do with your vibration isolators? Which ones are you using? How soft are they?
You're asking all the right questions, Josh. That wobble does appear to be at the gimbal's natural resonant frequency. Andy.
I'm using the stock isolators, I'm not quite sure how to quantify how soft they are but the gimbal floats around with very little resistance. I just put an order in at quadcopter yesterday, should I place one again today for stiffer rings?
Just before you go to the time and cost of ordering anything, can you tell me how you have got the pan Radian sensor connected up? What's plugged into each port, please? Also can you connect up the pan Radian sensor with the Radian software and take a screen shot of the Diagnostic and Configuration window while the Radian system is in Stabilized Slew mode and post that screen shot, please? We can double check to see if there's anything obviously set wrong. Thanks Andy.
I just installed the pan Radian on a AV130 and it is doing the exact same thing. It works well for holding heading and holds still when the air frame is still but small/slow movements cause this oscillation or stepping action. Of course my servo is different but I do know the servo will work very smooth with the 5:1 reduction that I have at this time. I think I may try a 6:1 or even 7:1 just to see what it does.
Hey Nick, Are you letting the airframe swing on it's own above the 3-axis gimbal. Try holding a hand on the boom to give it some 'mass' for the 3 axis gimbal to stabilize against. Things can get weird with stabilization systems when there is no mass for them to 'push' against. Tabb
Good point, Tabb -- and that "mass" would presumably be enhanced by the torque of the motors in flight, if I understand what's going on correctly -- and that's something missing from "dangle mode." Andy.
Hi Andy, Yes the multi rotor in flight is doing its best to hold heading, so it gives the gimbal something to torque against....as you said this does not exist in dangle mode. Tabb
So I just reviewed the footage from my first dual-op flight this evening and it's perfectly smooth. And I just tried another test in dangle mode without letting go of the booms and there weren't any oscillations. Thanks Josh, Andy, and Tabb for your help. I should have test flown before posting, I didn't really think about how dangle would differ from flight.
Glad all is well, Nick. Yeah, the in-flight dynamics are complex. All the more reason for kudos to Tabb, JohnC, Holger, Ingo for making the technology possible. Andy.