"Safe to fly - Non GPS"

[Not A Speck Of Cereal]

I think you've got it. Here's my take (someone correct me if I'm wrong):

"P/A/F all feel the same": Agreed. That is, out on an open field with no real wind, if you have it in P mode, it will pretty much hold its position. If you put it in A mode, it will drift around a bit based on the breeze / atmospheric conditions, not much, but enough to show that you are not locked on GPS. In F mode, it's pretty much the same as P, only you can do the IOC (Intelligent Orientation Control) missions.

Other observations:

P Mode: it does lock, but it also drifts. It doesn't drift the same way as A mode, it just doesn't lock to GPS on a dime.

For instance, I've been doing a lot of Litchi 3-level panos lately, 10 snaps per layer, so 32 snaps in all (2 bottom snaps). That takes up a lot of time and I've found that at the end of the procedure on a windy day, the craft is not really very near the spot it started on.

To see, find a fixed object in the distance in relation to the craft position at the start, then compare to where the object is at the end. Of course, the wind is helping it wander off, so if there is no wind at all, you might not have any significant drift. Note that for Panos, a bit of a drift isn't that big of a deal when it comes to stitching them together later in post, at least, when you've not close to any objects.

A Mode: it still kind of stays in position, meaning you could take your hands off the sticks on a non-windy day and see that it's not only NOT dropping out of the sky, it's pretty much staying where it is with only moderate drift.

With a little bit of wind, you will be making a lot of small corrections with your thumbs on the sticks, with just a jiggle here and there, then back to zero (stick to middle, as in fingers off the sticks).

With a more moderately stronger wind, those movements will be heavier to the point where you're using them just to maintain position and the sticks are not going back to zero much at all. In fact, your goal now isn't to hold position on a dime, but just navigate while expecting the craft to be buffeted around in the air. After all, that movement isn't a problem when you're up in the sky. Getting close to the ground to land is another matter, hence one more reason why a lot of us like to hand-catch-land.

To practice: put your bird up in the air on a mildly breezy day, switch to A mode, see it drift, move the sticks to correct. Also, try landing in A mode, but at first, not on a very windy day.

F Mode: same as P, except of course using IOC (Intelligent Orientation Control).

Chris

 

[matti]

put your bird up in the air on a mildly breezy day, switch to A mode, see it drift, move the sticks to correct. Also, try landing in A mode, but at first, not on a very windy day.

I guess A mode landing usually benefits if Vision Positioning System (VPS) is active, right? Does VPS override GPS horizontal-lock in low (under 3 meter) altitudes??

...does someone disable Vision Positioning System by default?

From the manual:

"VPS is activated automatically when the Phantom 3 Professional is turned on. It is only effective when the aircraft is at altitudes of 0.3 to 3 meters. It cannot work properly on surfaces without clear pattern variations or when operating above sound-absorbing materials. The aircraft will switch from P-mode to A-mode automatically if neither GPS nor VPS are available. Operate the aircraft with great caution in the following situations:

Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green). Flying over a highly reflective surfaces.

Flying at high speeds (over 8 m/s at 2 meters or over 4 m/s at 1 meter).

Flying over water or transparent surfaces.

Flying over moving surfaces or objects.

Flying in an area where the lighting changes frequently or drastically.

Flying over extremely dark (lux < 10) or bright (lux > 100,000) surfaces.

Flying over surfaces that can absorb sound waves (e.g. thick carpet).

Flying over surfaces without clear patterns or texture.

Flying over surfaces with identical repeating patterns or textures (e.g. tiles with the same design). Flying over inclined surfaces that will deflect sound waves away from the aircraft.

VPS may not be able to stabilize the aircraft when flying close to the ground (below 0.5 meters) at fast speeds.

Do not use other ultrasonic devices with frequency of 40 KHz when VPS is in operation.

The sonar sensor emits high frequency sounds that are only audible to some animals."

 

[Not A Speck Of Cereal]

I guess A mode landing usually benefits if Vision Positioning System (VPS) is active, right?

I guess. I never thought about VPS when landing, I just landed. It's always been outside when there wasn't a concern for needing visual ultrasonic assistance.

Does VPS override GPS horizontal-lock in low (under 3 meter) altitudes??

I don't know for sure, but I wouldn't think so. There would be no reason I can think of to ignore GPS lock when using VPS in landing logic. It seems to me that it would be an aid in addition to GPS location services, but again, I don't know for sure.

...does someone disable Vision Positioning System by default?

I have heard people say in these forums that they do, or that they consider VPS to be worthless (I forget why), but I do not turn it off myself.

Chris