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Post by thornton on May 30, 2014 7:16:17 GMT
J C . can u can u do this for us less experianced gimble tuners ..IM doing ok but im not sure how i got here ..and i fell i got a long way to go yet cheers TROU Thanks for all ur help so far
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Post by JohnC on May 30, 2014 16:54:11 GMT
Well, as a general method for tuning a servo based gimbal, I would tune each axis very roughly with the gain a bit too low so that it is not oscillating or anything to disturb the one you are tuning.
The first thing is to ensure the camera is balanced properly. You need to disconnect the servo drive for this as it drags too much for it to move freely under it's own weight. After this make sure any belts are tight and you can't feel slop between the movement of the gimbal and the servo (you will normally get a little bit due to the backlash in the servo gears).
Tune the roll axis first then the tilt and then the pan. For each axis:
Select the axis within the G-Lock software and open up the tuning graph from the main configuration window. You should see 2 lines being drawn : one is the amount of error for the stabilisation and the other is the rate of turn for the axis. During the tuning, you want to bring these lines as near to zero as you can without any oscillation.
For adjusting the gain, temporarily assign the 'gain' to a dial on the Tx so you can adjust it remotely. Also make sure the 'Rate' gain is zero. You will only add this if you need it.
Start rocking the gimbal by hand (so it is stabilising the axis) through about +/-40 degrees at about 30 degrees/second and adjust the gain until you get the best response. I normally take it too far so it oscillates to get the ballpark then back it off.
When you have it as good as you think it will get, test slewing the axis using the camera operators radio. You are looking for the smoothest line for the 'rate' on the tuning graph. You may need to adjust the gain for this. If you do, test by moving the gimbal by hand again that all is OK.
When you have the sweet spot, look on the main 'CARVEC G-Lock' window and see what the gain is. Copy this into the gain for the configuration window, turn off the 'gain' channel (ready for the next one) and write it to the module.
Repeat for each axis. If an axis tends to 'bounce' as you stop slewing it with the radio, try adding a bit of 'damping'. This will normally be a low value - 10% or around there.
Once you have done this, it's time to test it in action. If one axis seems to be less stable, assign it to the dial again and fine tune. If you do this, I would first mark the point on the dial where the gain from the Radio matches the gain you entered into the config window. You would then fine-tune either side of this position.
JohnC
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Post by thornton on May 30, 2014 17:29:26 GMT
Exelent !!! this great ..thanks JC .....got any more... a more in depth guide to the config window would be very good.. ..ie the tick circles to the right of the wizard box ---on left side --+90 +180 etc..these are not self evident throw in as many "in other words" as u can ...WE HANG ON UR EVERY WORD.. cheers trou
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Post by JohnC on May 30, 2014 18:11:51 GMT
One more tip is to hold your mouse pointer over any of the options or data boxes and you should get a 'tool tip' which explains what it does in more detail.
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Post by thornton on May 30, 2014 18:40:17 GMT
23 VIEWS mmmm .. got any more on how to use the TUNING GRAPH .. ... I dint even know it is a tool !!.. as radian didnt have it
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trou
Gimbal Cleaner
Posts: 2
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Post by trou on May 30, 2014 23:41:01 GMT
yellow line on all 3 axis is up at 8 on the graph .. gimble seems ok .. what do i do to bring it down
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Post by JohnC on May 31, 2014 7:46:56 GMT
Trou,
The yellow line is the actual angle of the gimbal for the current software. It shows where the gimbal is and as you slew the gimbal, you should see it move smoothly. If you move the gimbal by hand, you will see how much error is happening before the servo can correct it. To make it easier to see, slew the axis to zero before testing the stabilisation.
The blue line is the rate-of-turn of the axis - ie how fast it is turning.
The best you can do is increase the gain until you see signs of instability in the graphical display and then back it off a bit. To improve over that you are looking at upgrading the servo doing the driving. I expect the puny Freefly servo will gasping for breath driving your monster :-).
Remember that sometimes having a smooth blue-line is most important because it is how smoothly the camera is actually moving. Just tuning for the smallest yellow-line error can result in very small but jittery movements visible in the video.
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Post by thornton on May 31, 2014 18:29:22 GMT
morning john.. just about to start first full day of tuning .. many thanks for the reply.. im shure others will benifit from this discorse .. there is a level of customer support here that many have never seen before.. with other products.JC UR EVERY WORD IS GOLD .!! i remember ur valued advice over on the FF forum ....but now im gushing..... Ihave added a rotary motion damper to the tilt tray ..its filled with silicone. to take out the the backlash .. the servo can easely drive it as my final drive on tilt is 6.5 to 1 ...much more than the P H belt drive ..it provides a costant fluid force to the servo ..i do expect it to use more battery .. but i have tons of amps . watt are ur thorts on this ?? or should i just buy a BG85 and a module ?? I have 4 very stiff cables coming out the back of the camera up to the mount ..
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Post by thornton on May 31, 2014 21:35:05 GMT
JC ..how imprtant is it to keep the gimble absalutley still - stationary- when u power up ??
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Post by thornton on May 31, 2014 22:14:13 GMT
OK the ..ITT ENIDINE ROTARY VISCOUS DAMPER works very well.... im able to ad much more GAIN without jitttttttta they are $100 and small..a few ounces 55 mm dia . and a pain to get a shaft into unless ura machinist A freind loaded a servo full of heavy moly grease and got a good result on a small gimble
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Post by thornton on May 31, 2014 23:21:52 GMT
is 20% damping exesive
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Post by thornton on May 31, 2014 23:41:22 GMT
after an hour ..still cant get any response from the tuning graph ....how do u get it to go ?? however im getting the gimble to work pretty well now ...just on the bench THE VALUES ARE :- MAX RATE 40 TO FIXED 30 ACCEL 20 SLOWDOWN 20 how do these seem to u ? GAIN 50% DAMPING 20% Do i need anything in the proportional box ?? keep it clear ?? im just using sticks for the gimble .. and another DX61 ..ur fav .. for the dolly
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Post by thornton on Jun 1, 2014 4:46:29 GMT
WELL ...its now working quite ok on the bench .......BUT .... G-LOCK IS SO ACURITE ..that any slop or loosnense or backlash in the geartrian and ur doomed ......... To get ROLL to work smoothly and it does ..i stretched 4 rubber bands from the bottom of the roll cage up to where the roll servo ismounted so the servo is stretching the r b and stops the slop ROLL on an av200 has the most back lash ..as the plastic gear does not have a very strong splind and tends to whare fortunatley servos are strong and can handle a small force against them .. brushless cannot Ican see why G-LOCK would be supurb with brushless ...
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Post by JohnC on Jun 1, 2014 8:11:42 GMT
Yes - any slop is bad : the G-Lock can oscillate backwards and forwards around the slop. It's much worse for brushless - though as most are direct-drive it's easier to manage.
CX6 ? lol. OK as long as you don't want to do anything except use the sticks.
Did you get the graph working ?. remember to click the axis you want in the configuration window : it should start automatically when you open the graphing feature.
Your values look OK except be careful with the damping gain : use the minimum you can as it can cause oscillation - but is useful for giving the stabilisation a little 'kick' to get moving.
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Post by thornton on Jun 1, 2014 17:58:47 GMT
JC..in ur general method ... post above ..is that -10% gain as in minus 10% ?? i am finding that 1..3..5..7.. % gain as in low numbers is giving more jittta .. what about the proportional box . ..only using sticks for gimble control ... emty everything there..? Keeping it perfectly still at powerup ??
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