Car sensor at gate caused me to crash?

Airbroker · Jul 30, 2016

Flying my P3A through our gate - person at the gatehouse was going to open the gate as I approached. The car sensor (you can see on the left in the bushes) threw my drone into a sideways movement right into the bushes. I'm thinking the sensor threw my Phantom into atti mode before I could react. She fell on her back so everything seemed okay except when I rebooted her I got a "Warning: Motor Obstruction".

Got her home, removed the props and fired her up. No more warning and everything seems fine. One propellor was really difficult to remove - was jammed on real hard. Am going to try to fly her later this evening. Any thoughts? Click on "Crash" below to see film.

Crash

neven · Jul 30, 2016

Post txt log. Car sensor should not cause that

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Airbroker · Jul 30, 2016

Where do I find the txt log and how do I post it?

Meta4 · Jul 30, 2016

Airbroker said:
Where do I find the txt log and how do I post it?

It's in your phone/tablet
Go to https://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.

If you are using an Android phone or tablet, the flight records are in Internal Storage/DJI/dji.pilot/FlightRecord
They are all txt files and the file name includes the date.

Reed L · Jul 30, 2016

Yep, looks like it went into atti mode and drifted left because of the trees and hedges blocking the GPS signal, your logs will tell the story. That's an easy mistake just like flying under a bridge. With no gps the whole flying scenario changes rapidly. At least we always learn it well... after the first time...

shockwave199 · Jul 30, 2016

This is a good case for using the VPS. Sometimes it can make sense to use. There are also other ways to get tricky shots besides flying, to minimize the risk. Hand walking the drone through a shot or holding the drone on a bicycle. Even an investment in an osmo could be worth it for real estate filming. Point being, you don't always have to fly every shot to create the shot you're looking for.

sar104 · Jul 30, 2016

neven said:
Post txt log. Car sensor should not cause that

Sent from my SHIELD Tablet K1 using PhantomPilots mobile app

As far as I'm aware, most vehicle sensors are magnetic - they produce a magnetic field and detect the resulting energy loss when a metal object moves through it. I could imagine that the magnetic field might cause measurable interference with the aircraft compass at short range, leading to an erroneous heading indication and resulting course deviation.

neven · Jul 31, 2016

sar104 said:
As far as I'm aware, most vehicle sensors are magnetic - they produce a magnetic field and detect the resulting energy loss when a metal object moves through it. I could imagine that the magnetic field might cause measurable interference with the aircraft compass at short range, leading to an erroneous heading indication and resulting course deviation.

Aren't magnetic ones under the road? This one looks optical to me.

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sar104 · Jul 31, 2016

neven said:
Aren't magnetic ones under the road? This one looks optical to me.

Sent from my SHIELD Tablet K1 using PhantomPilots mobile app

I've never seen an optical gate vehicle sensor in that type of situation, but maybe. It's unlikely anything optical would affect the aircraft.

It's also unlikely that the aircraft would lose GPS lock in that location but, even if it did, then the IMU would not turn it through 90˚ like that.

Vertigo · Jul 31, 2016

sar104 said:
As far as I'm aware, most vehicle sensors are magnetic - they produce a magnetic field and detect the resulting energy loss when a metal object moves through it. I could imagine that the magnetic field might cause measurable interference with the aircraft compass at short range, leading to an erroneous heading indication and resulting course deviation.

I dont see how a compass problem could explain a lateral deviation. It will cause unintended yaw (incorrect heading), but not sideways movement like that.

Im gonna out on a limb and guess VPS was actually enabled and got confused by the surface.

shockwave199 · Jul 31, 2016

I had compass error and the bird flew with the breeze sideways. It apparently drops in atti mode with a compass error, or at least it did for me. Any number of things can bring on a problem in that situation, such as compass error, loss of gps, or the channel just too weak [dirty] and being dumped. Most of my odd flight behavior has happened really close to buildings where wireless networks are cranking out signal from inside. That's why I think that while drone can be cool for real estate, it can also be tricky and you have to really be on your game.

Wibble · Jul 31, 2016

Many garage door openers and gate sensors are radar - ie microwave. The automatic ones anyway.

Corey Tucker · Jul 31, 2016

looks like it just drifted over because of wind or poor gps. i wouldn't blame it on the car sensor or whatever. if i had seen it drifting, i would've just popped it up in altitude and avoided it. but looks like it was a soft crash anyway so no big deal.

BigAl07 · Jul 31, 2016

I'd say this would be a classic example of why you learn to fly the aircraft w/o all the stabilization so that when something goes wrong you are comfortable with correcting in a quick "instinctive" way.

Glad it sounds like it wasn't damaged, it didn't cause any damage to your client's property/vehhicles, and no one was close to it to get hurt. Mark this one up to good luck and spend some significant time flying the aircraft in manual mode in various situations so you're prepared and experienced should this happen again.

Also on a side note... repeating patterns (like the driveway) can create havoc with the Phantom VPS.