Espritmodel.com Telemetry Radio
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Old Nov 01, 2008, 03:02 PM
Old retired Electronics Fart
Charles B's Avatar
United States, OH, Centerburg
Joined Mar 2007
426 Posts
Return Home with new function

I just got a Idea last night . It would be a new function added to the return home function.

In your software when you take your plane off ,
You can record the start location then you would record the direction and elevation

into the EEprom for at least 30 seconds (100 samples should do the trick) .
That would give the fail safe return home a path to land the plane.

As you flying the plane if your path crosses the start path and it was lower
in height you could record it as the lowest return point to that path.

Of course it would have to be some where up the start path in time. That
intersect point would have to be like 10 seconds or more into the start slope
.

If the condition happen to make a return home function.
The software would go to that point and reduce the planes elevation
to make that intersect point . and the direction would have to be 180 degrees different that the start direction.

Then you could control the plane to follow the start slope to the landing point. If it tried to do a return home with the 180
degrees and it overshot it you could do the same slope and the same
direction . to face going into the wind. It would be better than running of
battery power.

This hole process would require the software to control

motor speed, elevation and direction.

Charles
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Old Nov 02, 2008, 07:36 AM
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remzibi's Avatar
Poland
Joined Sep 2004
816 Posts
The auto return function is more complicated then it looks like .
The function by her self is , let say "easy" - the problem is how to stabilize the plane (or heli) , if we have stable platform - not a problem .
For heli must be some kind of heli command or similar hardware , for plane it must be any gyroscopic system or IR as avaliable or very good trimed plane not affected by wind conditions (not possible) . If we will have such stable platform - home returnig including landing is possible to do .
So for now better to consider car or boaut for such platform and on them made some experiments for "autonomus movement" .
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Old Nov 02, 2008, 07:45 AM
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Greece
Joined Feb 2007
4 Posts
Hi.
remzibi, I've seen that you have amost finished this unit. Is it possible for you to post the Bascom AVR code so I can see how you control the Max ICs? I'm trying to make a backup camera with a distance overlay and your code will surely help me see how to control the MAX ICs.
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Old Nov 02, 2008, 09:05 AM
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United Kingdom, Bath
Joined Apr 2007
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Quote:
Originally Posted by remzibi
The auto return function is more complicated then it looks like .
The function by her self is , let say "easy" - the problem is how to stabilize the plane (or heli) , if we have stable platform - not a problem .
For heli must be some kind of heli command or similar hardware , for plane it must be any gyroscopic system or IR as avaliable or very good trimed plane not affected by wind conditions (not possible) . If we will have such stable platform - home returnig including landing is possible to do .
So for now better to consider car or boaut for such platform and on them made some experiments for "autonomus movement" .
Not only that, the GPS is only accurate to about 10m in altitude 95% of the time, which means for 5% of the time it can be off by more than 10m. Even if your plane has perfect control, the recorded GPS path may not be where you think it should be all the time. This is why full GPS landing in real life is still not possible.


Remzibi, how much for a board without the 7456, without GPS, but with everything else as a kit?
-Z-
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Old Nov 02, 2008, 09:50 AM
LKJ
Lars k Jensen
Denmark, Central Denmark Region, Tostrup
Joined Apr 2006
570 Posts
Sitron wrote :This is why full GPS landing in real life is still not possible. :
Actually GPS landing systems is being installed in Denmark right now, or in the wherry near future.
Its is done with one extra Gps on a known spot on the ground transmitting corrections real time to all airplanes around 50 KM radius, precision is around 10 CM in attitude and around the same in direction i think.
I think its already working in USA now. At least after what i know, they invented the system.
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Old Nov 02, 2008, 10:00 AM
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United Kingdom, Bath
Joined Apr 2007
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Quote:
Originally Posted by LKJ
Sitron wrote :This is why full GPS landing in real life is still not possible. :
Actually GPS landing systems is being installed in Denmark right now, or in the wherry near future.
Its is done with one extra Gps on a known spot on the ground transmitting corrections real time to all airplanes around 50 KM radius, precision is around 10 CM in attitude and around the same in direction i think.
I think its already working in USA now. At least after what i know, they invented the system.
I think I'm a couple years behind the state of the art!

Differential GPS has been around for a while with very high accuracy, but I didn't know they are actually already being used for landing! Still though, unless you can afford to carry a DGPS station with you when you fly, or can tune into someone else's station, GPS landing with a single receiver is not going to be reliable.
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Old Nov 02, 2008, 10:38 AM
LKJ
Lars k Jensen
Denmark, Central Denmark Region, Tostrup
Joined Apr 2006
570 Posts
Well about installation in Denmark i first learned that last weekend, soo actually only one week behind me.
Perhaps someone smart guy one day figure out how to use it for our purpose, ( hint hint ennyone ) I mean when the system is working can anyone use it ? or do we need some license ? i don't know.
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Old Nov 02, 2008, 03:18 PM
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Poland
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Quote:
Originally Posted by tolisn
Hi.
remzibi, I've seen that you have amost finished this unit. Is it possible ...
Megale , nasuvoitiso sigura - ta elava ta schemata , ma xriazume ligo elevtero chrono kai thaine etimo se ligaki . I wrote that just for exercises language I didn't use for long long time .
I have your materials - solution for you will be ready soon , look email from me .


Quote:
Originally Posted by zitron
Not only that, the GPS is only accurate to about 10m in altitude 95% of the time, which means for 5% of the time it can be off by more than 10m. Even if your plane has perfect control, the recorded GPS path may not be where you think it should be all the time. This is why full GPS landing in real life is still not possible.-Z-
I think that for altitude - without pressure indicator such landing will not be possible using only one GPS unit , or without cooperation from groud .


Quote:
Originally Posted by zitron
Remzibi, how much for a board without the 7456, without GPS, but with everything else as a kit?
-Z-
Hmm , as chips are mountig by hot air - max is mountig also in the same process (on my desk ) . For kit with spare part I must warn you that runing device can not be so easy as you think .
So you must decide for clean board (all SMD elements you will take from used or broken PC cards/boards recover them by hot air) - or assembled and working device with preprogramed bootloader (what i reccomend for avoid make running problems , max'es just send to me) . However if you have any other proposal let me know .
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Last edited by remzibi; Nov 02, 2008 at 03:24 PM.
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Old Nov 02, 2008, 11:16 PM
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Greece
Joined Feb 2007
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Thanks for your help remzibi
Na ise kala patrioti
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Old Nov 03, 2008, 09:34 AM
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Charles B's Avatar
United States, OH, Centerburg
Joined Mar 2007
426 Posts
The GPS system in the USA that is go to a .25 of a inch (6.2mm) uses this system to
get the accurate reading.

They first put in a fixed location GPS receiver and computer.

That receivers computer keep track of the error it receives from its
GPS receiver. It then sends via 2 way radio the data signal to the unit that
need the accurate heading. That computer takes the error offset on its GPS
receiver and that corrects for the error. That ERROR is caused by the signal
getting to the earth via the GPS Satellite.

That is how the USA farmers can have there crop planters put the rows
in the middle of the rows they planted last year. All the data for that field is
keep on the fixed computer for usage from year to year. They also use that
data when they pick a crop. and that way they can tell what part of the
field need more fertilizer . There planting the next spring will then correct for
low crop output.
Even old equipment can be update to use this new GPS system.
One unit has a motor that drives a wheel the drives the steering wheel on
the tractors . It just clamps on.

Charles
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Old Nov 04, 2008, 01:35 PM
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tty044's Avatar
Joined Aug 2008
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Quote:
Originally Posted by Charles Beener
. That ERROR is caused by the signal
getting to the earth via the GPS Satellite.

That is how the USA farmers can have there crop planters put the rows
in the middle of the rows they planted last year.
Charles
Please correct me if I am wrong but the "signal" is the Time Base needed for precise position calculation. This Time Base is not getting an error due to travelling through atmosphere but due to military service that distort it a little bit (civillian services and others like terrorists will not be using it for precise navigation). This distorion is floating in its character, thats why it is impossible to correct it in simple "shift".The precision of under 1 m is not possible without correcting floating Time Base. Even then in systems like Galileo or Waas/Egnos precision will not be higher than 0.5 - 1 m. And one simple rule - when you pay you get better accuracy (clear Time Base). I am not gps specialist but I wrote here what I heard or read.
Best regards
Michal
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Old Nov 04, 2008, 02:46 PM
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Remzibi - Gratulacje i Polska Gola!!!!
Szkoda, ze nie mam aktualnie czasu aby zajac sie tym projektem ktory jest naprawde super!!!

Pozdrowienia
Homer
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Old Nov 04, 2008, 04:29 PM
Old retired Electronics Fart
Charles B's Avatar
United States, OH, Centerburg
Joined Mar 2007
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Quote:
Originally Posted by tty044
Please correct me if I am wrong but the "signal" is the Time Base needed for precise position calculation. This Time Base is not getting an error due to travelling through atmosphere but due to military service that distort it a little bit (civillian services and others like terrorists will not be using it for precise navigation). This distorion is floating in its character, thats why it is impossible to correct it in simple "shift".The precision of under 1 m is not possible without correcting floating Time Base. Even then in systems like Galileo or Waas/Egnos precision will not be higher than 0.5 - 1 m. And one simple rule - when you pay you get better accuracy (clear Time Base). I am not gps specialist but I wrote here what I heard or read.
Best regards
Michal
Even with paying for the precision time base your still don't the accuracy
with out a GPS fixed reference . As weather changes the delay in the GPS
signal affect it accuracy . My cousin farm has been using that system for
two years and the Ohio department of highways also uses it but they add in
the satellites on 1240Mhz to 1575.42Mhz and they use a fixed GPS Receiver.

I was told that there accuracy is .1 inch.

U.S.A. ham that use 1200 Mhz to transmit TV signals have to stay away for
1240 Mhz by 6 Mhz so we don't interfere with there GPS receivers. Even
though the rules say we can transmit there. Were not allowed it interfere
any guidance system . The 1240Mhz GPS Satellites are Russians Satellites
and they don't care where they put they frequencies.


Charles
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Old Nov 11, 2008, 02:16 AM
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Hi

Can you please publish your project details on this forum, I think it will help to most of users in the world wide (http://rc-cam.info/viewtopic.php?t=131 is not English forum)
In this case if you can publish Circuit diagram along with part list, and software, will be nice.
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Old Nov 11, 2008, 04:03 PM
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remzibi's Avatar
Poland
Joined Sep 2004
816 Posts
Quote:
Originally Posted by lankaunicorn
Hi

Can you please publish your project details on this forum, I think it will help to most of users in the world wide (http://rc-cam.info/viewtopic.php?t=131 is not English forum)
In this case if you can publish Circuit diagram along with part list, and software, will be nice.
OK , as it is interestet for readers , I will do some translation in English .



The waether is not so good for testing (very windy) but thanks for sacrifice of betatesters , first movies from air ready :
2008-11-09 Chudoby - OSD Remzibi test2 (8 min 2 sec)


In this case possible problem of GPS jamed by videoTX , too short distance between videoTX and GPS module . However everything working OK .

Here another with very cheap and popular Navibe GM720 (SIRFSTARIII chipset) mouse GPS module .
2008-11-11 Chudoby - OSD Remzibi test GM720 (9 min 44 sec)



The picture quality with and without OSD are not changing , the basic functionality I declared for that unit , is accomplished .

Right now I am modyfing software to have fully customize layaout by user .
After that for easy way to do that , will need to write part working on PC .
If any one is good PC programer - welcome .
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Last edited by remzibi; Nov 11, 2008 at 06:01 PM.
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