Lost and Found Drone - Losing and Finding our Shrike
We lost and luckily found our Shrike this week! So what happened? Long story, but we believe the following occurred to create the situation:
1.) We were flying from inside a car (Tx only, vRx was mounted on top of the car) which was no doubt reducing the range of our Tx.
2.) APM was set for a 45% throttle cruise speed for Auto & RTL, which for our airplane, was not enough to safely return it home in the 20mph head wind we were facing during RTL.
3.) When the airplane was at it's furthest point, it lost signal from our Tx, causing it to kick into Failsafe, which is to Loiter once, and then RTL.
4.) The airplane went into loiter, gained a little connection from our Tx, returned to back to Auto (the mode we were in), then lost connection, when to loiter, gained signal return to auto, etc. all the while a 15-20 mph wind is carrying it further and further away.
5.) When we finally turned the Tx off to allow the APM to only RTL, it was too late, the battery was too weak and the wind too strong for it to RTL.
It eventually lost enough power to safely land with stabilization carefully returning it to level and controlled decent.
What did we learn & what are we doing to fix it? A ton. We literally have over 50 tasks to make prevent this from happening and to aid it recovery. A few of the main ideas:
1.) Get the Tx out of the car to improve range
2.) Set failsafe to skip the loiter and go straight to RTL
3.) Increase RTL throttle rate to allow for headwind recovery
4.) Place a buzzer on the plane to assist in recovery
5.) OSD/Telemetry to assist in navigation
6.) Elevate vRx to increase signal quality
and many, many more.
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Comment by Hasufel on June 30, 2012 at 8:52am -
A great episode in the MyGeekShow series: "It's a miracle!". Heh :)
Keep it up Trent & Nick, learning by mistakes is the best way.
Lost a quad a bit like you did and luckily retrieved it - added loc8tor since on it.
Hope to see Ep.78 today with new stunts :)
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Comment by Zen on June 30, 2012 at 9:18am -
You should also invest in a Millswood Failsafe Device, or wait until diydronesafety.com comes out with theirs.
http://diydronesafety.com/entry.php/1-Just-ordered-two-Millswood-En...
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Moderator Comment by Gary Mortimer on June 30, 2012 at 10:03am -
Only do auto stuff up wind of you. Then if it goes wrong its blowing back over you.
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Comment by Trent at MyGeekShow on June 30, 2012 at 10:24am -
Hasufel: You're so right. We learn more with failures than we do with successes.
Zen: Very interesting! A very good option & assistant with recovery.
Gary: Agreed! That is one of our 50: "Wind Speed and Direction consideration with Mission Planning"
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Moderator Comment by Gary Mortimer on June 30, 2012 at 10:34am -
Yep weather is a big factor, I try not to fly in wind speeds that are greater than 50% of my cruise speed.
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Comment by Dave on June 30, 2012 at 10:59am -
Maybe a future feature for APM a buzzer that comes on after a settable length of time, useful if you forget to unplug the battery or loose your aircraft ! - Or to beep at any other event low battery, time, etc
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Comment by Mark Bateson on June 30, 2012 at 11:16am -
You were incredibly lucky to locate the plane - wow, just another 50 feet into that tall grass and it would have been really tough to visually locate ... or a gated road or private property with dogs. Glad you were able to locate it and it all worked out okay.
And respectfully I would like to suggest that flying right next to a freeway or for that matter, now that you're showing us your maps planning your flights over the freeway is not a good idea. I know it's highly unlikely but just imagine if your plane came down on the freeway and caused an accident. You always think it might never happen but just like you had amazingly good luck finding your plane - luck can also take a different turn. The best way to help prevent an accident is to try and avoid it in the first place. Looks like you have lots of rural areas to fly so please consider planing your flights over farmland.
I always enjoy your videos, your passion and determination - keep improving your system, learning and having fun.
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Comment by Helldesk on June 30, 2012 at 11:25am
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I know that feeling, including the against-all-odds recovery. Include your contact details in the aircraft right away and look into a defense-in-depth strategy for failsafe and recovery. Independent methods of locating and perhaps direction finding, and so on.
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Comment by Brian McGrath on June 30, 2012 at 11:34am -
Definitely go to CP antennas on both video transmitter and receiver and consider using a helical antenna on the receiver (much more directional) to assist in direction finding and extending the receive range. Not sure the frequency you are using (900mHz, if I recall correctly). Antenna size might become an issue with a helical unless you are considering going to a shorter wavelength (5.8gHz, perhaps).
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Comment by Toby Mills on June 30, 2012 at 12:35pm -
A car roof is actually a really good place for an antenna. Mounted in the center it will use the roof as a ground plane and considerably extend the range. An antenna inside the car will have the opposite effect.
Also use the APM minimum ground speed feature. In wind this will increase the throttle to ensure you don't go backwards.
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