Ideas / suggestion for adjusting alignment of MWC

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joshuabardwell
Posts: 7
Joined: Mon Aug 25, 2014 4:35 pm

Ideas / suggestion for adjusting alignment of MWC

Post by joshuabardwell »

I am setting up my first quad, and using MWC. I'm having some trouble getting the alignment of the FC exactly right. It would be ideal if this problem could be solved in software, and I think it probably can. I have found references to forcing sensor orientation, which I think is what I'm looking for, although I haven't run down the details yet. It would be excellent if there was an option similar to ACC Trim where one could use stick commands to adjust the FC orientation in real time. So, take off; hover; pitch forward. If the quad drifts to the right, land, and use a stick command to virtually rotate the FC to the left. Likewise, if the FC was tilted slightly, it could be adjusted in software.

I know some out there are probably thinking, "How hard is it to just adjust the FC." I'm holding my FC onto my copter with foam tape, so each time I move the FC, I have to peel off the old tape, replace it, and then cross my fingers that the new orientation is more accurate than the old one. By carefully measuring, I have got it within about five degrees, but the copter still doesn't go straight forward/left/back/right when I give the appropriate stick input from a hover.

I guess I haven't really asked a question per se. If anybody has any suggestions as to how to best address this, I'd love to hear them.

carlonb
Posts: 210
Joined: Sun Apr 03, 2011 6:29 pm

Re: Ideas / suggestion for adjusting alignment of MWC

Post by carlonb »

joshuabardwell wrote:I am setting up my first quad, and using MWC. I'm having some trouble getting the alignment of the FC exactly right. It would be ideal if this problem could be solved in software, and I think it probably can. I have found references to forcing sensor orientation, which I think is what I'm looking for, although I haven't run down the details yet. It would be excellent if there was an option similar to ACC Trim where one could use stick commands to adjust the FC orientation in real time. So, take off; hover; pitch forward. If the quad drifts to the right, land, and use a stick command to virtually rotate the FC to the left. Likewise, if the FC was tilted slightly, it could be adjusted in software.

I know some out there are probably thinking, "How hard is it to just adjust the FC." I'm holding my FC onto my copter with foam tape, so each time I move the FC, I have to peel off the old tape, replace it, and then cross my fingers that the new orientation is more accurate than the old one. By carefully measuring, I have got it within about five degrees, but the copter still doesn't go straight forward/left/back/right when I give the appropriate stick input from a hover.

I guess I haven't really asked a question per se. If anybody has any suggestions as to how to best address this, I'd love to hear them.

The better is to fix the FC in solid way, I think you will have vibration issues.
After that, if you change the FC position (the front Arrow must be Always aligned) the roll and pitch may be out of few millimeters, no problem, you MUST DO the acc calibration, and then if necessary adjust with stick calibration when in hovering. That's all.
One more think, this is important only Flying in Horizon mode, in Acro mode you only need to trim with RC sticks.
Bye

joshuabardwell
Posts: 7
Joined: Mon Aug 25, 2014 4:35 pm

Re: Ideas / suggestion for adjusting alignment of MWC

Post by joshuabardwell »

Sorry--are you suggesting that the FC should not be vibration isolated from the frame, or that it should be?

kilby
Posts: 76
Joined: Wed May 28, 2014 10:17 am

Post by kilby »

The APM and Naza flight controllers prefer to be pretty well isolated from the frame otherwise the flight controllers do weirdass things.

Most multiwii folks that I know (and in my case the Naze) tend to have their flight controllers hard mounted but it does mean being sure of balanced props and motors.

But that's on fairly stiff frames compared with the Naza and APM folks use

carlonb
Posts: 210
Joined: Sun Apr 03, 2011 6:29 pm

Re: Ideas / suggestion for adjusting alignment of MWC

Post by carlonb »

joshuabardwell wrote:Sorry--are you suggesting that the FC should not be vibration isolated from the frame, or that it should be?

I'm using multiwii and my FC is hard mounted, of course I use the gyro filter at 42 Hz and the props are well balanced.
In the past I've added some foam, but with bad results.

waltr
Posts: 733
Joined: Wed Jan 22, 2014 3:21 pm
Location: Near Philadelphia, Pennsyvania, USA

Re: Ideas / suggestion for adjusting alignment of MWC

Post by waltr »

At the most, my MW FC's have a small (3mm ID) rubber 'O' ring on each side the the mounting holes.

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