DJI A2 Performance/Build Comparisons

J

jazzboy

Member
kloner said:
to the best of my knowledge it's not a fasst thing as much as using the 8fg that i feel is important...... any other variation has it's quirks or at least did in the begining....

Is everybody that hates this issue with the features not working? whats the exact cause that's crashing it? is there any iosd logs of a crash i can check out?
Click to expand...
I will be following your lead. I got my single stick working fine but I have a gig in the next week (weather permitting) and my radio needs some tuning so I picked up a Futaba FG-8 Super and it has really good stick centering and feel. The only thing is that I fly pinch style on dual stick and the top switches are crazy tight. But the Futaba looks like the best option for now. Will post test results in a couple days.

Thanks for your info as things like gain ideas are really great to have as a reference.

Andy
 

J

jazzboy

Member
Posted this over in RC Groups as well.

Just finished mounting my A2 and did the indoor dirty maiden. All my multis pass this first test as if they are not safe inside they won't be safe outside...but never do this! ;-) Stock gains feel lively with no gimbal weight. The install is very compact and perhaps another option to mounting the two components together. I was thinking of mounting the IMU on top of the main box but this over and under setup leaves a wee gap between them.

Dirty air maiden


Under

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Top

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Rear with 10 cent antenna masts

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Top installed

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J

jazzboy

Member
First day outside for the A2. (aslo on RC Groups)

-Good loiter.
-Jerky flight in Atti (was alone so not in video).
-Good waypoint angles.
-Bad waypoint times as all were set to 5 and in the video you can see the times
vary wildly.
-Both GPS positions were too far east by about 20 feet.
-And sorry for the cr*p video quality, had to stabilize....yuck!

Overall ok but aggressive on stock gains and a few strange artifacts. BUT not as good as the NAZA 2 on the exact same set up and IMU location out of the box. Maybe tuning will help???


Panorama waypoints then loiter

 
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J

jazzboy

Member
Thanks for the offer, I really appreciate it but no iosd. The main issues are the hold time variances and the 20 foot offset. The offset might be due to Google Maps/Earth but I think they are pretty accurate. Maybe hold time is calulated only for location time and not hunting time.....Ed?
 

kloner

kloner

Aerial DP
it is a weird deal how they time that, if mine lock in then hunts and relocks, it spends all kinds of time on scene,,, think it starts the count over. We've had too high of gains make it never find the spot, wind on occasion gets it locked up like it needs to sit on such a small plate to consider being there. Were not running differential gps here, close is close enough.... too low gain it drifts off, too high it hunts, just right it works most of the time as advertised.
 


kloner

kloner

Aerial DP
it's a combo that you can see in the osd data if it's working right or looking all over or not caring.... shows in motor output

I hear quite a bit of surging in yaws,,, indicates maybe not level props or too small of props for the airframe?

start with a no wind day then if it kills it, throw it up in wind and see how it acts. the thing sounds good from the video, not hunting, might still be a tad bit low in manual gains.... get the basic gain into a grouped switching and atti onto it's own bank and move them exponentially but set endpoints so it can not go to extreme ends of the gain in case you would go the wrong way and give it small adjustments while you can see it close but in a waypoint pattern like you showed. adjust it till it starts working with itself....

try atti gains down from 90 through 110 while it's locked into a gps hold, basic gain could be high on that frame, might be towards 140-160. whats stock, 120? i forget

it has that a2 locked in look
 

J

jazzboy

Member
kloner said:
it's a combo that you can see in the osd data if it's working right or looking all over or not caring.... shows in motor output

I hear quite a bit of surging in yaws,,, indicates maybe not level props or too small of props for the airframe?

start with a no wind day then if it kills it, throw it up in wind and see how it acts. the thing sounds good from the video, not hunting, might still be a tad bit low in manual gains.... get the basic gain into a grouped switching and atti onto it's own bank and move them exponentially but set endpoints so it can not go to extreme ends of the gain in case you would go the wrong way and give it small adjustments while you can see it close but in a waypoint pattern like you showed. adjust it till it starts working with itself....

try atti gains down from 90 through 110 while it's locked into a gps hold, basic gain could be high on that frame, might be towards 140-160. whats stock, 120? i forget

it has that a2 locked in look
Click to expand...

Good call. I was going to set the two front dials on FG-8 for basic and and atti gains. Props are 15x5 and were perfect on the previous incarnation. The surging on yaws happened when I was testing a PX4 on this frame and vanished with the Naza V2. Stock basic is 140. Will post when I try the new gains. Thanks.

Andy
 

kloner

kloner

Aerial DP
props level like ruler on the prop adapter and it hits the next prop adapter. usually even a pinned frame has some degree of variance there.... that creates a pre yaw the algo doesn't handle as well.

your welcome
 

J

jazzboy

Member
kloner said:
props level like ruler on the prop adapter and it hits the next prop adapter. usually even a pinned frame has some degree of variance there.... that creates a pre yaw the algo doesn't handle as well.

your welcome
Click to expand...

Will re-check the angles. Should be out again tomorrow, weather permitting.
 


J

jazzboy

Member
Anyone have a good system to determine the vertical center of gravity once a large gimbal is added to an octo? Left to right and front to back are easy as I balance my craft to a center point but the vertical will be tricky.

Andy
 

kloner

kloner

Aerial DP
i pick em up by any two opposing arms and look at how it falls when it leaves a nice flat surface.... quad to octo, works good.... might also make sure the cg is set on where the gimbals cg is in relation to the 3rd axis if there is one
 

J

jazzboy

Member
kloner said:
i pick em up by any two opposing arms and look at how it falls when it leaves a nice flat surface.... quad to octo, works good.... might also make sure the cg is set on where the gimbals cg is in relation to the 3rd axis if there is one
Click to expand...

The horizontal axis are fine but I am in a quandary as to how to suspend the craft to ascertain the vertical cg once the gimbal is added.

Andy
 

kloner

kloner

Aerial DP
i've never sweated it, just guessed the number holding up a ruler and guessing where the weight would be and input in assistant.... they act fine
 


P

PeterLester

Member
We used to do this way back in 1st year university in Physics 101:
If you can determine the center of gravity of each part and its mass then you can use that information to determine the center of gravity of the system by summing the system mass moment of inertia. Where the sum of the first moments = zero you will find the center of mass. But also CAD programs that do 3D SOLID modelling will instantly do that for you provided you first input all above data. The manual method does not take long.

Obviously you will need to suspend each component individually from each of the 3 axes to establish first the c of g of each component.

http://www.engineering.com/Ask@/qactid/1/qaqid/3411.aspx


jazzboy said:
Anyone have a good system to determine the vertical center of gravity once a large gimbal is added to an octo? Left to right and front to back are easy as I balance my craft to a center point but the vertical will be tricky.

Andy
Click to expand...
 
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S

sk8brd

Member
Kloner i'm trying to help a guy that has had some issues with motor's cutting out on a2 setup. can't deter main if it's an esc prob or a fc issue. do you think you can peek at his log-i don't know how to read the logs yet to help him. i can email or post here let me know. Thanks!
 
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