DragonOSD+V2 with RTH - Page 154 - RC Groups
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Jul 16, 2010, 09:51 AM
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RacerX208's Avatar
Originally Posted by kempo
.....Looking forward to test the waypoint software, I want to play with it before the end of this month, if it is possible of course .
Thats next on my list of "To Do's"
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Jul 16, 2010, 10:03 AM
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kempo's Avatar
Originally Posted by RacerX208
Thats next on my list of "To Do's"
Some "behind the scene" info regarding waypoints? Maybe a screen capture with the software ?
Jul 16, 2010, 10:58 AM
Registered User
I think the IR sensors are old technology. Why 2 cents for IMU development.
Jul 16, 2010, 11:22 AM
Registered User

The EagleTree sensor is kinda low on resolution. If you review videos of them in action, you will find that the resolution is kinda low. It can probably be made to work though, being that it's I2C. I just don't think it's worth it because there are better sensors around.

As for the video about how IR sometimes behaves wrong, try this:-

Untitled (22 min 50 sec)

(about 5:17 into the video)

(about 37 seconds into the video)

I would qualify that these examples are not directed at the OSD but about the issues with IR sensors and thermal environment. The very nature of these sensors make them susceptible to certain types of issues but they work well enough for 80-90% of the time.

Jul 16, 2010, 02:05 PM
Fly the Discombooberator!
magnetman's Avatar
3. Would you prefer I work on improving the ArduIMU (there are limits to this), or finding a better IMU (for example, maybe one of the FY-xx devices), or making my own IMU design?


Thermopiles are outdated now, IMU is the way to go! I'm sure your design would be superb!! - But, there also must be some good units out there to adapt??

Jul 16, 2010, 02:08 PM
plus vite plus loins
Funjet2008's Avatar
finding a better IMU
finding a better IMU
finding a better IMU
Jul 16, 2010, 02:27 PM
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RacerX208's Avatar
Jul 16, 2010, 05:47 PM
I love FPV!
Cralis's Avatar
Originally Posted by Daniel Wee

The EagleTree sensor is kinda low on resolution. If you review videos of them in action, you will find that the resolution is kinda low. It can probably be made to work though, being that it's I2C. I just don't think it's worth it because there are better sensors around.
Thanks Daniel.
When you say resolution, do you mean how often it updates? I see the Honnywell one is 3hz. Would the resolution have a bad effect on, say autopilot, or anything else? I ask, as the ET one is $37.. with silicon tube, pitot tube and the device, and no soldering required - for my skills, pretty good. The Honeywell one requires lots of soldering and resistor work. Plus I'd need to source silicon tube from somewhere, as well as something to use as a pitot tube. And also, the installation... With the ET one, I just made a hole in the nose and put the pitot tube though... and had a static pipe connected somewhere too. When you say that it could work with the DOSD+, would it need a mod, or would I just need to ensure that the 4 wires go into the right 4 pins on the board?

I'm not 100% sure how accurate the thing was...

This was a flight I did with my, now dead, EasyGlider, a few months back.

That is reporting GPS Speed and Airspeed. I think the blue one is GPS speed, and you can see that the purple one seems more accurate in that, it seems more stable. I'm not sure why there is such a difference though... I don't have the higher res version...

But the GPS take off and landing height is different slightly... as is the barometric height...
Jul 16, 2010, 05:51 PM
Registered User
Kmart's Avatar
If the wind is blowing 20mph from the North, and you are flying 20mph in a Northern direction, what is your airspeed? 20mph. What would your ground speed be? 0. GPS Speed is your ground speed.

So, flip that example- 20mph from the north, and you are flying 20mph Southward. Your airspeed is still 20mph, but your ground speed will be 40mph.

If the plane was sitting on the ground, and a 20mph wind hit it, the airspeed will read 20mph, while your GPS speed is 0 (sitting on the ground).

Also, what you can see in a lot of FPV videos, is if you dive straight down, your GPS speed may say something like 5mph- you could be going 80mph downwards, but only 5mph across the X axis.

Hope that helps. some.
Jul 16, 2010, 05:56 PM
I love FPV!
Cralis's Avatar
Yip, Kmart, I agree. Problem is, with that graph, I was always consistantly flying with a tail wind (Airspeed slower than GPS speed). With my skills, I usually fly with close to zero wind. At least, when that graph was created.. I would only fly when the trees were standing still. This has since changed, but in that flight, I don't think it's the wind that's causing the difference.


I'm a fool!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
That's my GPS ALTITUDE vs Barometric!! Sorry, it's not airspeed at all!


And damn, I don't have an Airspeed comparison graph. Sorry!
*feels like a monkey*

Also, Kmart, those are the reason I want to see airspeed instead of ground speed. I think in a plane, ground speed is really pretty irrelevent.
Jul 16, 2010, 06:06 PM
what goes up, must come down..
AussieHoppy's Avatar
My name is Hoppy
I am an addicted fpv noob.

My 1.5 cents- continue as you have been Daniel, to develop new technology with stronger reliability.

When proven it works well, give me instructions on how to make a board, I'll have a go to make my own IMU

IMHO, my limited understanding is DOSD V2 is going to be something else then DragonTracker.... why not complete the entire system with newer IMU technology?

I'll go hide now....

Jul 16, 2010, 07:31 PM
I love FPV!
Cralis's Avatar
OK, some nice guy has kindly passed on a graph of the two airspeeds.


So - would this sort of data not be good enough for RTH or any other function that uses airspeed?

kmart - in this graph you can celarly see that there is a down wind and an upwind flight, as you mentioned. Pretty cool to see..
Jul 16, 2010, 08:04 PM
I love FPV!
Cralis's Avatar
RTH testing posponed til either later today, or tomorrow.
I was all ready this morning - dead calm, but then my dog started acting up, and could stand properly!

So, I had to take him to the vet... and by the time we got back, there was a small breeze.. Nothing major, but Daniels post says I should try in calm... so hopefully it dies later, but tomorrow morning looks good...
Jul 16, 2010, 10:57 PM
Registered User

When you say "hopefully it dies later", I assume you were not talking about your dog but the wind.

As for the resolution, I was thinking about the actually reading, not the rate of reading.

The problem with making a current sensor is that it takes time, money and work. All of which I don't have a lot of.

Actually, I think the Honeywell sensor is very easy to solder.

Jul 17, 2010, 12:19 AM
I love FPV!
Cralis's Avatar
Crashed!! And this time... I have NO idea what caused it. I did one short flight, and the plane went into a spiral, so I landed... and reversed the ailerons.

Launched, and it just banked right and went in...

And then.. I could smell that horrible burning smell!!!

ESC was beeping as if it had lost contact.

Opened the canopy... actually, the canopy came off... and I unplugged it all. I powered down my ground station. Then, I powered up the plane again.. and the ESC armed OK, and the servos twitched. But.. I had no control of aileron or elevator (the two things going into the OSD). So I powered down... and then noticed that a power pin had melted off, and the power to the OSD was detatched!!!

So, I packed up, and came home...

I see that again... the ground cables are all melted on my video harness!!

Argh!! Starting not to enjoy this now...

Analysing video, as I recorded it all...

Post crash: I've just reviewed the crash, and it's a mistake I made.
I changed the settings... and then removed my goggles to do a LOS launch... BUT.. I forgot to exit the menu!

So I had no control of the plane.. except for Throttle.......................................... ....

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