GPS Rescue, Is It Worth the 10 Extra Grams?

[kpixels]

Does it really work? What if you're in acro mode, upside down and lose signal? Curious so I bought a couple of these just to experiment around with. I plan on testing one on a Chameleon and the other on a tricopter build I have planned. Any thoughts or ideas from anyone who's tried this or is thinking about it.
@LitterBug Do you know if this will work with dRonin?

A couple of videos I watched that got me thinking about trying it;

 

[ElectriSean]

It does work. I haven't tried it myself but my friend runs it on a couple of his mid-range quads. Essentially it puts you in angle mode, levels out, climbs and starts flying back. It's not perfect but it can save you from an Rx loss.

 

[LitterBug]

I have my A450 still thanks to a GPS and FrSky telemetry. Got behind a dense row of trees on the south side of the field and lost my FPV feed. Thought for sure it was in the row of trees. searched, listened for beeper, etc... no dice. Then I took the coordinates off my TX, plugged them into google maps, BAM!, found I had been looking 150 yards in the wrong direction. RTH is NOT a guaranteed thing if you have been flying aggressively in acro. Accelerometers can get biased and not know which way is up unless you can hover upright before switching to leveling/RTH. You also have to have a barometer and compass. Those GPSes should work with dRonin. I've been playing with the autonomous modes lately, and it's not just plug in and go. Need to calibrate the accelerometer and compass so the FC knows for sure which way is up and which way is north.
Cheers!
LitterBug

 

[kpixels]

I have my A450 still thanks to a GPS and FrSky telemetry. Got behind a dense row of trees on the south side of the field and lost my FPV feed. Thought for sure it was in the row of trees. searched, listened for beeper, etc... no dice. Then I took the coordinates off my TX, plugged them into google maps, BAM!, found I had been looking 150 yards in the wrong direction. RTH is NOT a guaranteed thing if you have been flying aggressively in acro. Accelerometers can get biased and not know which way is up unless you can hover upright before switching to leveling/RTH. You also have to have a barometer and compass. Those GPSes should work with dRonin. I've been playing with the autonomous modes lately, and it's not just plug in and go. Need to calibrate the accelerometer and compass so the FC knows for sure which way is up and which way is north.

Thanks LB, It might be worth it in some cases just for the gps telemetry because they are only $15. Your 450 might still be lost. I thought the RTH was a stretch for a freestyle. Neither the Bardwell F4 (Chameleon) or the DTFc (tricopter) have the barometer or compass built in. Will probably only add the compass + baro to the DTFc, should be fun.

 

[LitterBug]

Thanks LB, It might be worth it in some cases just for the gps telemetry because they are only $15. Your 450 might still be lost. I thought the RTH was a stretch for a freestyle. Neither the Bardwell F4 (Chameleon) or the DTFc (tricopter) have the barometer or compass built in. Will probably only add the compass + baro to the DTFc, should be fun.

Unfortunately, the DTFc does not have an exposed I2C buss so adding a compass and baro isn't an option. I'm using a Seppuku on my A450 for full blown testing of as many features I can turn on at one time. :-D

 

[kpixels]

Just my luck! Could still log gps with TX though. Might try on my old tricopter with Naze32 10DOF.

 

[Bricks]

We have found a few lost quads buy using a patch antenna as long as the battery is still connected.

 

[kpixels]

Yes, me too! I had one go down in some thick woods. Even though there was no video signal from my location after the crash, I took an fpv monitor plus a patch antenna from my goggles on my search. After some serious searching and nothing there was very faint picture on the monitor. Switched to the patch antenna and was able to head right to it.

 

[varg]

I think I'm going to try this out. I recently lost a quad on the first flight when the video signal unexpectedly went out on me at my local RC field during a turn. Long story short it wound up going into failsafe after drifting beyond a treeline, and when it went down I think it landed in a canal. This would be useful for that situation, upon losing video signal it could at least bring it close enough for me to land it line of sight if no video signal could be recovered.

 

[kpixels]

Sorry to hear about your quad. Lost 2 within a month a few years ago so know the feeling. Let us know how it works if you do any testing. Haven't had the chance to mess with mine yet.

 

[varg]

Will do. My next build will have it, and I'll be sure to record the testing. I'm also using a telemetry capable receiver on this build, so I should be able to log my GPS coordinates to my transmitter.

 

[varg]

The quad is built and flying and the GPS works, I get valid coordinates on my OSD, 12 sats, speed output, altitude, distance to home and the arrow points the correct direction, but my first test of the GPS rescue mode was a bust. I flew it about 280ft out and about 20ft above the ground hit the switch. It dropped to the ground. Luckily I had the foresight to do it low to the ground so it didn't hurt anything when it dropped, not even a prop. The documentation seems to suggest that it's because I didn't fly far enough away because I was within the descent distance (set to 100m). I do not have enough space at the spot I was flying to test as the documentation prescribed (100m past the descent distance) without passing over a treeline. I will play with the settings and test it again tomorrow at a much larger spot where I have at 600-700ft to the nearest treeline depending on where I take off from. I'll probably reduce the descent distance to 50m anyway.

FWIW I'm using a Cicada F4 All-in-one FC/ESC combo with betaflight 3.5. It's a very convenient package especially with a pretty low profile frame (Martian IV) but it only has one spare input (for GPS) and no pads to solder to for a spare UART/smart audio.

 

[varg]

Just an update on this. I've luckily not had to use it but lately I've been building quads for people and installing GPS on them and the one person who has had a loss of sight of the quad and used the GPS rescue mode in that situation had the quad go in the wrong direction despite the rescue mode being tested good after the build. Unfortunately he flies line of sight so we're very short of details, but it went in some direction other than the launch point and disappeared. I've been trying to figure out what would cause that, and haven't come up on any leads. So here's a caveat for you all; if you're one of those line of sight guys, don't expect this to help you in the slightest because you will be wholly unable to verify that you had a good GPS lock when you took off. One of the routine checks I do with any flight as a habit is to check that the "direction to home" arrow on my OSD is pointing in the correct direction and that the "distance to home" as I fly by my launch point is reasonable.

 

[kpixels]

Just an update on this. I've luckily not had to use it but lately I've been building quads for people and installing GPS on them and the one person who has had a loss of sight of the quad and used the GPS rescue mode in that situation had the quad go in the wrong direction despite the rescue mode being tested good after the build. Unfortunately he flies line of sight so we're very short of details, but it went in some direction other than the launch point and disappeared. I've been trying to figure out what would cause that, and haven't come up on any leads. So here's a caveat for you all; if you're one of those line of sight guys, don't expect this to help you in the slightest because you will be wholly unable to verify that you had a good GPS lock when you took off. One of the routine checks I do with any flight as a habit is to check that the "direction to home" arrow on my OSD is pointing in the correct direction and that the "distance to home" as I fly by my launch point is reasonable.

Thanks for sharing all this info, is definately useful. I had to put all my build projects on hold last Fall because one of my sons got hurt. Good thing I had my Reverb built and have been able to fly (learn fpv) maybe once a week (6-10 batts). His recovery is going well so I'm hoping to get caught up on things and dust off some projects.
I couldn't help thinking about gps rescue on Christmas Eve. My Reverb went down in the tall grass/brush that surrounds our RC field that afternoon. I wasn't paying attention to voltage and pushed the battery to next to nothing. One habit I picked up from this forum is to record every flight in my goggles so I could play it back if it goes down. In this one case it did not record. The battery was still connected but it was so drained that I couldn't use the directional locator technique that @Bricks mentioned.
My poor Reverb had to sleep under the stars Christmas Eve. On Christmas after about one hour of searching with my Phantom and 2 hours grid search on foot with metal detector finally found it. It was right on top sitting upright, no damage, just hard landed. It blended in so well that later when I looked at the Phantom footage, I had flown right over the spot where I found it several times but you can't see it in footage or high res photos. All together I searched rough terrain for more than six hours, two in the crispy cold dark, ho ho ho.
In the short term I think I'm going to start using ViFly for the freestylers. Hope to test these gps on a few of my larger multi-rotors builds soon...

 

[kpixels]

At least someone got it to work;

 

[varg]

Testing it like bardwell did in that video is all well and good, I do that, but if you don't verify that your home point is good when you're flying it's not going to help any. I've hit the GPS rescue switch on both of my quads many times just to see what it will do and it has come back towards me every time, aside from that one time I hit the switch too close and it just disarmed. It's worth it for the speed function alone, I've been able to get my overpowered Kopis 2 build up to over 130mph.