Reason for flyaway

[BlackTracer]

This is in direct response to this thread, http://www.phantompilots.com/viewtopic.php?f=27&t=33205, but may explain a good number of other flyaways as well.

Here goes: The OP described what he thought was everything was ok and he took off. He had slow flashing greens and 10 sats. What he didn't have just yet was a home point ready to be recorded when he starts motors. The firmware has to initialize the home point to something, I am betting (0, 0). So when the Phantom gets in the air, it has good sat lock and position, but home point is still (0, 0). It immediately thinks it is out of the radius limit. It flashes rapid reds (says so in the manual), as reported by the OP, and flys off towards (0, 0) to try to get within the radius limit (says so in the manual). A perceived flyaway.

I also think once it enters this mode, it may be in an execution loop that does not update the home point even if it were to acquire one after it starts this behavior.

A way to get out of this is to switch to ATTI or manual when it starts to do this. You have to be thinking quickly on your feet.

This behavior can be likened to grabbing the phantom by the skids and dragging it away from its current location with no controller input. Once let go the phantom will try to return to the point where it was grabbed. So the flyaway is like instantaneously teleporting the phantom to a location far far away from its home point. Except in this case it is a special case in the firmware of being out of the radius limit. Hence the rapid reds and take off with no control.

What do you guys think? Ready to get shot down cause I probably forgot something important.

 

[happydays]

Hmmm, if he had slow flashing greens would this not indicate that the HP had been set? On all of my phantoms, the HP sets almost instantly when six sats are acquired.

 

[BlackTracer]

Hmmm, if he had slow flashing greens would this not indicate that the HP had been set?

Not on mine. I have to get the second set of rapid greens, indicating home point is ready to be stored on motor start.

On all of my phantoms, the HP sets almost instantly when six sats are acquired.

Same with mine. But this may not always be true in all cases. I have nothing to back this up lol.

 

[dbfletcher]

On all of my phantoms, the HP sets almost instantly when six sats are acquired.

I was under the impressions that HP doesnt get set/recorded until you csc to start the motors (or maybe it was take off... but csc makes more sense to me)

 

[MapMaker53]

I never rely on the bird to automatically set the home point on its own. I don't trust it. So much so that I manually set a home point while it is idling on the ground and then set a new HP when I get it up overhead where I confirm the rapid flashing lights a second time. Call me ****.

 

[N017RW]

On all of my phantoms, the HP sets almost instantly when six sats are acquired.

I was under the impressions that HP doesnt get set/recorded until you csc to start the motors (or maybe it was take off... but csc makes more sense to me)

I believe that may be the fact regarding the actual time time the location is 'stored'.

Step 1 (a) of the "Naza-M Home Lock Usage" section on this page suggests that...

http://wiki.dji.com/en/index.php/Naza-M ... on_Control

 

[LordEvil]

I never rely on the bird to automatically set the home point on its own. I don't trust it. So much so that I manually set a home point while it is idling on the ground and then set a new HP when I get it up overhead where I confirm the rapid flashing lights a second time. Call me ****.

I do the exact same thing, never had a problem with my bird, takes only a couple of seconds.

 

[Mako79]

This is in direct response to this thread, http://www.phantompilots.com/viewtopic.php?f=27&t=33205, but may explain a good number of other flyaways as well.

Here goes: The OP described what he thought was everything was ok and he took off. He had slow flashing greens and 10 sats. What he didn't have just yet was a home point ready to be recorded when he starts motors. The firmware has to initialize the home point to something, I am betting (0, 0). So when the Phantom gets in the air, it has good sat lock and position, but home point is still (0, 0). It immediately thinks it is out of the radius limit. It flashes rapid reds (says so in the manual), as reported by the OP, and flys off towards (0, 0) to try to get within the radius limit (says so in the manual). A perceived flyaway.

I also think once it enters this mode, it may be in an execution loop that does not update the home point even if it were to acquire one after it starts this behavior.

A way to get out of this is to switch to ATTI or manual when it starts to do this. You have to be thinking quickly on your feet.

This behavior can be likened to grabbing the phantom by the skids and dragging it away from its current location with no controller input. Once let go the phantom will try to return to the point where it was grabbed. So the flyaway is like instantaneously teleporting the phantom to a location far far away from its home point. Except in this case it is a special case in the firmware of being out of the radius limit. Hence the rapid reds and take off with no control.

What do you guys think? Ready to get shot down cause I probably forgot something important.

I had the same theory. Its to do with the MAX height and MAX radius settings. I call this the GEOFENCE.
The only way to validate that is to look at the birds behaviour. I know that when you fly out of the Geofence, as per the phantom assist, you only have "throttle and rudder commands". If you still have those 2 commands but it continues to "fly-away" then yes, the theory is correct.

There are 2 things I do to prevent this.
1. I set MAX Height and MAX radius to 9999999999999999. Doesn't help if you travel further than this...
2. Look on the radar or ground station. If the RADAR = NA don't fly. If it starts giving you 0.0 or more distance than you are good to go. In ground station, a Green H point will depict where you are and the airplane will be the phantoms reference point.

 

[rickasaurus]

When in Naza mode, it seems many are not aware of, or don't think to check, the rapidly flashing green lights. Watch the green lights closely after they first come on. After 6+ sats are locked in, the bird then seeks the current heading, and next the home point. Each one is signified by a few seconds of rapidly flashing green lights, then reverts to the slow flashing, signifying RTF in Sat mode. So if you observe both these sets of rapidly flashing green lights, you can be confident that the Course Lock and Home Lock, and RTH should work, as long as 6+ satellites are maintained.

 

[knowonecares]

Is this correct or close? NAZA Mode: Power On Phantom. Green Yellow Red combo a couple times quick = Warm Up. Green, Red, Red, Red repeated = Satellite Search. Ten to twenty seconds later, First Rapid Fire Green Flashes = Craft Orientation is recorded (for Course Lock flight). Then more Satellite Search with Green and Red (number of red flashes diminishes as it Locks In Satellites). After a number of seconds (maybe a minute or more it depends on location) Second Rapid Fire Green Flashes = 6+ Satellites Detected and Home Point is now Locked. The Return To Home Point is recorded, and Home Lock flight is possible. Finally, Slow Green Flashes = Ready for Take Off. And you recommend manually setting it while idling ,and again once it is hovering above your take off point? (Flipping the left
S2 switch 5-times and getting Rapid Fire Green?) Is this because up in the air you have better SAT lock?

 

[Mako79]

Is this correct or close? NAZA Mode: Power On Phantom. Green Yellow Red combo a couple times quick = Warm Up. Green, Red, Red, Red repeated = Satellite Search. Ten to twenty seconds later, First Rapid Fire Green Flashes = Craft Orientation is recorded (for Course Lock flight). Then more Satellite Search with Green and Red (number of red flashes diminishes as it Locks In Satellites). After a number of seconds (maybe a minute or more it depends on location) Second Rapid Fire Green Flashes = 6+ Satellites Detected and Home Point is now Locked. The Return To Home Point is recorded, and Home Lock flight is possible. Finally, Slow Green Flashes = Ready for Take Off. And you recommend manually setting it while idling ,and again once it is hovering above your take off point? (Flipping the left
S2 switch 5-times and getting Rapid Fire Green?) Is this because up in the air you have better SAT lock?

On NAZA mode, GPS lock can be acquired before Course Direction Lock and vice versa. If the phantom still has erroneous GPS data, it can rapid flash before the DIrection Course Lock.

And yes, the higher you are, the better chance of sat locking. This also helps with setting a new RTH/failsafe height. If failsafe is triggered, it will go that extra 20M higher from that mid air home point reset. Good if you have high obstructions.

 

[wkf94025]

And yes, the higher you are, the better chance of sat locking. This also helps with setting a new RTH/failsafe height. If failsafe is triggered, it will go that extra 20M higher from that mid air home point reset. Good if you have high obstructions.

Good point I hadn't thought of. Will remember that for the future.

I also manually set home point shortly after takeoff.

Kelly

 

[yorlik]

I never rely on the bird to automatically set the home point on its own. I don't trust it. So much so that I manually set a home point while it is idling on the ground and then set a new HP when I get it up overhead where I confirm the rapid flashing lights a second time. Call me ****.

Folks in the know, please add to, confirm, or correct this statement....

I ASSUMED home point was not just a latitude and longitude, but ALSO altitude. If you set home point 50 feet in the air, is that of any value?

When I 'lost' mine from stupid flying, it went over trees, 1500 feet away way out of site. I raced after it in golf cart, never got near it, finally went out of controller range and on dejected return to home, video came on saying 'going home!' I watched it come back and LAND where it had taken off. I don't think I like the idea of an 'attempted landing' with RTH 50 feet in the air?

 

[dalebb]

I never rely on the bird to automatically set the home point on its own. I don't trust it. So much so that I manually set a home point while it is idling on the ground and then set a new HP when I get it up overhead where I confirm the rapid flashing lights a second time. Call me ****.

Folks in the know, please add to, confirm, or correct this statement....

I ASSUMED home point was not just a latitude and longitude, but ALSO altitude. If you set home point 50 feet in the air, is that of any value?

When I 'lost' mine from stupid flying, it went over trees, 1500 feet away way out of site. I raced after it in golf cart, never got near it, finally went out of controller range and on dejected return to home, video came on saying 'going home!' I watched it come back and LAND where it had taken off. I don't think I like the idea of an 'attempted landing' with RTH 50 feet in the air?

I have seen videos on this, no matter how high you set the home point it will keep coming down till it lands, (that includes in water). :shock:

 

[CYeutter]

Setting the home point at a 50 foot altitude should not be an issue. It's not like the bird will descend to the 50 foot mark, think it's on the ground and turn it's engines off. It will keep descending slowly until it senses no more downward movement.
Regarding when the home point is acquired. I always thought that as soon as I see a value in the "Distance" field on my monitor, the home point has been established. Is that not the case?

 

[N017RW]

That may indicate it has a valid position fix but the location is not actually stored until you apply 10%+ throttle.
Academic really but that's what DJI has published.

See this page about mid-way down:
http://wiki.dji.com/en/index.php/Naza-M ... on_Control

 

[Meta4]

I ASSUMED home point was not just a latitude and longitude, but ALSO altitude. If you set home point 50 feet in the air, is that of any value? .. I don't think I like the idea of an 'attempted landing' with RTH 50 feet in the air?

As mentioned above the Phantom will not land at 50 ft but setting home point in the air is useful as a way of custom setting your RTH height which will be 20 metres above your home point. It also gives positive confirmation that home point is set.

 

[flyNfrank]

A fix for the "0,0" issue would be for the firmware to be written for us to be able to set & enter our Home Point as the default override. At any point when the motors are on/active while you have the quad staged on the launch pad, then at the point the quad see 6 plus satellites, it should be written to flash a message on the monitor screen asking to set the default home point such as "Set Home Point Now?". Then say if the satellite count drops below the 6 satellite count number, the message expires.

If the above suggestion was added to our quads, it would be golden!

 

[SteveMann]

A way to get out of this is to switch to ATTI or manual when it starts to do this. You have to be thinking quickly on your feet.

I postulated this exact theory a few months ago. But even in ATTI mode, the "return to fence" is still working and has priority. Manual is the only way to save the Phantom if this happens.

 

[Mako79]

A way to get out of this is to switch to ATTI or manual when it starts to do this. You have to be thinking quickly on your feet.

I postulated this exact theory a few months ago. But even in ATTI mode, the "return to fence" is still working and has priority. Manual is the only way to save the Phantom if this happens.

Makes sense. The IMU controls the Geofence height and the GPS controls the Geofence radius.
I think its best to remove the geofence and set to max 999999999 for both and use common sense and always keep your eyes on the telemetry.

I wonder how the Geofence works with Dynamic home point, especially in regards to the 2 second lag/ping.