Autopilot may be confused, and never return home. - workaround needed.

[AndreK]

Hi.
(I have now a good, working, autopilot on ailerons.)

but I discovered a problem that would cause me to lose my model permanently if I enabled autopilot, and flew out of radio/video range.

-Some clouds may cause the AHI to be drawn with a 20 degree roll at certain heading. - for example when flying west.

-Imagine you are flying north, home is at south 500meters.
-now you engage autopilot.
-Autopilot will starts to turn west, banks maybe 10degree, and does it until it's heading west.
-When it reaches the course where AHI was drawn like "10degree" - it continues to go straight - as it "thinks" it's banking 10degrees.
-I also see the AHI being drawn as if you had a nice roll, the problem is, this is because of the sky in the side of horizon.
- So autopilot "thinks" it has a nice bank, when, in fact, plane goes straight (and west).
-Now the plane will continue like this till I disable autopilot - if I did not, it would most likely fly like this for many kilometers.

- this was caused by clouds, but if I were near to a mountain-side, the same would have happened.

The problem is that autopilot seems to rely on AHI to detect it's turn.
It seems to ignore that the bearing stops to change for many seconds.

Workaround must be this logic : "If bearing does not change while turning for x seconds" then "increase roll limit" - "until bearing changes in right direction"

Please add this, this will prevent massive f*ckups near buildings, mountains, and clouds like this on one horizon.

(Also, the same clouds affects pitch.)

[Alex Villa]

Very good point... taking note

[elpimous]

hello all.

Andrek, could you explain what you did to permit autopilot with ailerons ?!!!:p
I must change rudder on/out with ailerons in/out ! Correct ?
(programs changes will be done with elevator and elerons ! correct ?!!)

What program changes did you do, please ?!!!

Thanks, and soon...some archos 5 videos !!!

Vincent.

[bjacobs00]

hello all.

Andrek, could you explain what you did to permit autopilot with ailerons ?!!!:p
I must change rudder on/out with ailerons in/out ! Correct ?
(programs changes will be done with elevator and elerons ! correct ?!!)

What program changes did you do, please ?!!!

Thanks, and soon...some archos 5 videos !!!

Vincent.

Good luck with those Archos videos. I have a 705 Wifi and I would say it's operation is marginal at best. The most annoying thing it does is split the recorded video up into multiple files. I noticed it usually does this because at some point during the video it mistakenly thinks the source is copy protected. This means you can't copy the incorrectly protected portion of the video to your computer or to another other device.

I contacted Archos support about this and they basically said, sorry, we don't have a fix for this. Well, thanks alot Archos, I won't be buying any more of your products!

On a different note, I would really like some more advice on how to calibrate the artificial horizon. Are you guys setting neutral rudder and elevator positions during a flight or on the ground? If on the ground, do you need to make sure the camera view is centered on the horizon when doing this or it doesn't matter? Also, I am trying to hold the plane while setting these values which I think may throw the FMA sensors off (thermal from my body maybe giving false readings to the sensors). Should I try setting these values while the plane is sitting level on the runway instead of holding the plane? Sitting level on the runway doesn;t exactly line up with the horizon so this seems like not the correct thing...

[Alex Villa]

Good luck with those Archos videos. I have a 705 Wifi and I would say it's operation is marginal at best. The most annoying thing it does is split the recorded video up into multiple files. I noticed it usually does this because at some point during the video it mistakenly thinks the source is copy protected. This means you can't copy the incorrectly protected portion of the video to your computer or to another other device.

I contacted Archos support about this and they basically said, sorry, we don't have a fix for this. Well, thanks alot Archos, I won't be buying any more of your products!

On a different note, I would really like some more advice on how to calibrate the artificial horizon. Are you guys setting neutral rudder and elevator positions during a flight or on the ground? If on the ground, do you need to make sure the camera view is centered on the horizon when doing this or it doesn't matter? Also, I am trying to hold the plane while setting these values which I think may throw the FMA sensors off (thermal from my body maybe giving false readings to the sensors). Should I try setting these values while the plane is sitting level on the runway instead of holding the plane? Sitting level on the runway doesn;t exactly line up with the horizon so this seems like not the correct thing...
The best way to adjust the AHI is by setting neutral rudder and elevator in the air, but you can make a preadjust while holding the plane above your head, while setting neutral elevator make sure not to have your body on sight of front and rear sensors, an setting neutral rudder make sure not to have your body on sight of the lateral sensors.
Also make sure the AHI is working properly before attempting to use the autopilot.

[chiloschista]

- this was caused by clouds, but if I were near to a mountain-side, the same would have happened.

Are you shure this is caused by clouds?
You are flying on snow and water.
Has anyone ever measured effective temp of clear sky vs. cloudy sky and snow or cold water?
I suppose sky temp would not vary so much as it could change on ground with snow, water (cold lakes in winter) etc.

[AndreK]

Yes, there were some "high" clouds (at low and high altitute) on only one side of the horizon (they "filled that part) , far away.

I have many hours experience flying over snow, water.
and this phenomenon was only seen recently, but I did not see that the recorder was stopped - I even thought I created a video of it (circled to display these clouds.)

[Alex Villa]

I am thinking about this, since this is that awfull moment in wich the attitude sensors cant be trusted. Unfortunatly we are seeing here the limits of the FMA sensors, so this lead again to use the GPS as main source of information. Allowing the GPS information to decide any increase on roll limit is very dangerous and need to be done very carefully.

[elpimous]

Hello, ANDREK.
hello all.

Andrek, could you explain what you did to permit autopilot with ailerons ?!!!
I must change rudder on/out with ailerons in/out ! Correct ?
(programs changes will be done with elevator and ailerons ! correct ?!!)
is there any problem in menus with this change ?
Thanks.:o
Vincent.

p.s: bjacobs00, archos 5 is a non-finished product (bad firmware ) but it's a super product, and it rec. nice quality videos.

[AndreK]

Hello, ANDREK.
...
I must change rudder on/out with ailerons in/out ! Correct ?
...
is there any problem in menus with this change ?
...



yes, you only need to switch connections.
no specific change needed, but you may need to adjust rate of turn limit, bank integral gain and bank proportional gain , and/or invert the channel in order to make it work with the "new" control surfaces.

Also, you will now change value with right thumb (if you fly mode2) - not rudder. - and value "up" is to move stick to the left. - I already asked for future software to be able to select control surface in software, rather than swapping cables.

[elpimous]

Thanks, Andrek.
I'll try this soon..
vincent:)