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Old Apr 15, 2010, 02:57 PM
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Eagle Tree: Request for Magnetic Compass Sensor

Been enjoying my FPV flights on my T-Rex 500 immensely. The heading compass sensor is enjoyable to watch as it moves with the aircraft.

But one thing I noticed is that the heading reading data comes from the GPS sensor. This is fine for "coordinated flight" where the velocity heading coincides with the aircraft's nose heading. However, in helicopter flight, one can do un-coordinated flight for long stretches at a time.

Intuitively, I think most people tend to thing the heading is the aircraft's nose heading and not from the actual velocity vector heading (GPS movement). It gets confusing when one is hovering slowly observing the ground and the heading indicator can start flipping around wildly. You can also notice this wild effect during helicopter takeoff and landing. It comes from the fact the GPS velocity reading isn't accurate until its start moving maybe 5mph or faster. Under that speed, the noise in the GPS signal gives erroneous "jumpy" readings. When I start doing more acrobatic moves like helicopter stall turns, the OSD heading can be off for a few moments in the opposite direction before it "snaps" into the new heading.

What is needed is a new sensor and one that uses a magnetic compass as its data sensor. Eagle Tree can then have an option setting to switch between GPS and magnetic readings (similiar to the setting to switch between GPS and airspeed sensors). Ideally, the OSD may overlay the two ontop of each other where the heading shows the magnetic compass heading with a small 'tick' that shows the velocity vector heading (GPS). I believe the difference between these two can also be used to give a "quality of turn" indicator as well like on real aircraft?
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Old Apr 15, 2010, 04:54 PM
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Hi,

It is already done, if you have a data recorder, if you have the elogger, you can ask for support for it, http://www.rcgroups.com/forums/showt...e#post14171402
But it costs $150

Megafluffy
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Old Apr 16, 2010, 12:08 AM
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Hi,

It is already done, if you have a data recorder, if you have the elogger, you can ask for support for it, http://www.rcgroups.com/forums/showt...e#post14171402
But it costs $150
Interesting components. I didn't realize that an electronic compass would be so complicated! I found a 2-axis super tiny compass for vastly cheaper cost at $30 and down to less than $24 each if purchased in 100+ volumes.

http://www.sparkfun.com/commerce/pro...oducts_id=7892

I can see this component being in a $40 to $50 plug-and-play Eagle Tree component! I would be first in line to buy an Eagle Tree compass sensor!
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Old Apr 16, 2010, 01:52 AM
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Weree, unfortunately that compass does not have tilt compensation. The one we support is that one's big brother, that does have the compensation. That one has up to 2 degrees of compass error for every 1 degree of tilt, so you can imagine the results you'd get while flying.
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Old Apr 16, 2010, 03:34 AM
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Originally Posted by billpa View Post
Weree, unfortunately that compass does not have tilt compensation. The one we support is that one's big brother, that does have the compensation. That one has up to 2 degrees of compass error for every 1 degree of tilt, so you can imagine the results you'd get while flying.
Hi Bill. I had no idea there was any support for an electronic compass. Is there a PDF or webpage you could direct me to that describes the component to buy and how exactly to wire it up?

Is the $150+ price tag prohibitive to building an actual plug-n-play Eagle Tree compass sensor? Or is there one already in the works? We heli FPV pilots could use one and I think would help advance the Eagle Tree OSD product to higher levels of RC aviation! Particularly if both the velocity heading and compass heading could be combined in a way similiar to what I described in the original post.
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Old Apr 17, 2010, 12:21 AM
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Weree, here's the component to buy:

http://www.sparkfun.com/commerce/pro...oducts_id=8656

It requires connection of a 4 pin cable, and installation of a diode, so it's not quite plug & play. :S

I hope we will be able to release a reasonably priced compass soon. $150 is way too expensive.
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Old Apr 20, 2010, 05:30 PM
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Originally Posted by billpa View Post
Weree, here's the component to buy:

http://www.sparkfun.com/commerce/pro...oducts_id=8656

It requires connection of a 4 pin cable, and installation of a diode, so it's not quite plug & play. :S

I hope we will be able to release a reasonably priced compass soon. $150 is way too expensive.

Good to hear that the compass sensor is in the pipeline. This year I will get full 2-axis head tracking on my heli's FPV camera. I just got the goosebumps a bit thinking how cool it would be to attach the compass sensor right on the pan/tilt mount and watching the OSD heading indicator track my actual head movements!
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Old Sep 19, 2012, 02:27 AM
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Originally Posted by billpa View Post
Weree, here's the component to buy:

http://www.sparkfun.com/commerce/pro...oducts_id=8656

It requires connection of a 4 pin cable, and installation of a diode, so it's not quite plug & play. :S

I hope we will be able to release a reasonably priced compass soon. $150 is way too expensive.
Hi Bill. I just had to resurrect this thread from 2010 regarding the possibility of an EagleTree compass sensor! Back then, your estimated price of an accurate EagleTree magnetic compass sensor with triaxial compass would be $150.

Since 2010, a lot of things have happened. Like the flood of multirotor aircraft along with a couple dozen associated open source and commercial flight controllers to choose from. Advanced autopiloting features are fairly common nowadays -- these features require the full 9-axis IMU sensors along with GPS. Almost all smartphones and video game controllers nowadays have them too. So these sensors seem to have become a commodity.

For instance, here is a 9-axis IMU: triaxial accelerometer + triaxial compass + triaxial gyro for $18.30 retail:

http://www.dealextreme.com/p/gy-85-6...arduino-148436

Could an EagleTree compass sensor be built on something like this? It could be even cheaper if you source a part with just the triaxial compass. As I mentioned in 2010, we FPV rotorcraft pilots need it. When hovering in place, the GPS compass is just bad because there's no movement. This is also true when sitting on the runway with a fixed wing FPV aircraft.

Other benefits:
  • OSD can display both nose heading and GPS velocity vector heading simultaneously. Example: The main compass view will come from the new compass sensor and a moving 'tick' indicator can be mapped onto the compass showing the GPS heading
  • Headtracking benefits: Would be so very awesome since moving my head will also move the compass where ever I look in near real time provided the compass sensor is placed on the pan/tilt assembly itself
  • Compass sensor data can be used to improve EagleTree RTH perhaps
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Old Sep 19, 2012, 04:09 PM
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Hi Weree, thanks for the feedback! We are working on a compass now, but how we end up packaging it has not been finalized.
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Old Sep 24, 2012, 01:30 AM
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Hi Weree, thanks for the feedback! We are working on a compass now, but how we end up packaging it has not been finalized.
I hope the compass can be made available separately. It would really help out and add to the OSDPro's usefulness.

I ran into another situation where the compass heading combined with GPS heading would really help out. I was at high altitude with my T-Rex 500 and noticed my GPS ground speed was over 50mph. I wanted to come to a dead stop "high hover" but realized I didn't actually know which way the heli was traveling to even start braking action! It took some fumbling to slow down but never actually completely stopped. Kinda ridiculous. As you know, at a certain high altitude, no motion is apparent especially coming from an FPV camera. This isn't even a problem at lower altitudes with ground cues.

I was thinking of a new graphical symbol in the form of a small circular reticle. The top part of the reticle always is the heli nose heading. A small indicator travels along the reticle's circumference indicates the actual direction of travel according to GPS. This circular stuff always makes the UI more cool! This reticle also be useful trying to hold a hover at low altitudes depending on how fast and accurate it is. A good solid hover might just turn into a game of trying to center this reticle! Once no motion is detectable by GPS, perhaps some other visual indication can happen on the inside of the reticle.

The software rendering this new graphical instrument needs to calculate both compass and GPS vectors. Not sure how much CPU cycles it would take but this reticle would be too cool a tool!
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Old Sep 25, 2012, 10:38 AM
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Hi Weree, thanks for the feedback! We are working on a compass now, but how we end up packaging it has not been finalized.
However packaged: Preorder!

Reliable directional information is essental for FPV flying and RTH in windy
conditions.
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Old May 30, 2013, 07:15 AM
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Originally Posted by billpa View Post
Hi Weree, thanks for the feedback! We are working on a compass now, but how we end up packaging it has not been finalized.
Re-re-resurrection. Ive been desperately googling for a OSD with a tilt compensated magnetic compass for my Trex 600 build and this is all Ive found, any update on weather or not ET will be releasing a compass or can somebody direct me twards a 3rd party sensor addon?
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Old Jun 06, 2013, 01:09 PM
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Hi, I do think we'll have a good solution for you later this year, but I don't have a release date or details for it, unfortunately. Sorry about that!
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Old Jun 06, 2013, 01:39 PM
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Hi, I do think we'll have a good solution for you later this year, but I don't have a release date or details for it, unfortunately. Sorry about that!
Any beta testing spots available, or pre orders? Was about to get an open source board and develope my own to suit my needs.
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Old Aug 30, 2013, 08:54 AM
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Hi, I do think we'll have a good solution for you later this year, but I don't have a release date or details for it, unfortunately. Sorry about that!
I too would be happy to beta test a compass module in my quad.
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