Return Home on a P4

pdmike

pdmike

Extremely Popular Member
Last weekend, I launched my P4 from a circular table in our back yard. I let it hover over the table for about 30 seconds to make sure it got a good look at the launch point, then I flew it. I flew it over the house and into the front year/street area, where I boogied it up and down the street for a while until the battery was getting low. I didn't think the battery was that low, but apparently it was, because the quad went into automatic Return Home mode.

It flew behind the house and then began to descend (I thought) to the launch point - the circular table. When I got into the back yard, it was about four feet above the middle of our circular spa and descending. It was one of those "think fast" moments. I didn't think fast enough to disable Return Home but, somehow, I was still able to move it away from the spa and land it in some nearby ivy. No harm.

But this raises a question for me. When the quad is fixing on the launch point, how does it do it? Is the fix based on GPS coordinates or on a visual that the camera records? I suspect it's GPS, but I'm not sure. The reason I mention visual is that both the table and the spa are circular, although the spa is a much bigger circle than the table. The table was a good 25 feet away from the spa. What do you think happened here?

Thoughts/comments?
 
My guess is that the VPS got the circular images mixed up but it may also have something to do with the home position. Do you manually record your home position before you take off?
 
Hi it works like this when you calibrate the compass and it gets its GPS lock it then knows where it is and were the transmitter is . It uses this to return home as you walked out front of the house it lost a fix on the transmitter it still had a fix on take off point but it likes both
Try next time to keep transmitter were it was when you calibrate it should then return home to with in a few inches of were it started , I tested my P1 in very strong wind and it still landed within a foot of its take off point
I also found it you fly in IOC mode and fly behind yourself all controls go strange they go back to front , it does this because you turn round so the transmitter is now backwards to the Phantom (as it sees it )
 
holtneil said:
Hi it works like this when you calibrate the compass and it gets its GPS lock it then knows where it is and were the transmitter is . It uses this to return home as you walked out front of the house it lost a fix on the transmitter it still had a fix on take off point but it likes both
Try next time to keep transmitter were it was when you calibrate it should then return home to with in a few inches of were it started , I tested my P1 in very strong wind and it still landed within a foot of its take off point
I also found it you fly in IOC mode and fly behind yourself all controls go strange they go back to front , it does this because you turn round so the transmitter is now backwards to the Phantom (as it sees it )
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Thank you! I haven't calibrated the compass for my back yard - only for a baseball diamond several miles away. Today (with the compass still not calibrated for my back yard) I flew again from the back yard. I tried return home only this time, I was standing right next to the circular table which I thought was the launching point. I het return home and the little sucker descended to several feet off the patio floor, 10 or 15 feet away from the table, and just sat there. If I tried to lower it, it only came toward me. Finally, I thought to hit the return home button and look at the screen. When I slid off for return home, I was able to land it OK.

So - next flight, we calibrate the compass first thing. I suspect things will go a lot better then.

Not clear on one thing. Are you saying you have to have the transmitter close to the home point in order to use return home?
 
Also, make sure your home point is set in the DJI Go4 to the take-off location, not the transmitter location. I will say that this is completely outside my experience with mine. It always seems to be within inches of the take-off location, although I never let it completely auto-land. I always cancel it and fly the last bit down manually.

You shouldn't need to calibrate your compass for such a small change in location. However, you should always check your compass and IMU in DJI Go4 before flying and ensure they are reading in the green.
 
Phantoms are known to do fly away you should calibrate the compass every time you change flight locations or it may one day head off to its last calibration point which can be miles away
 
Rick M said:
Also, make sure your home point is set in the DJI Go4 to the take-off location, not the transmitter location. I will say that this is completely outside my experience with mine. It always seems to be within inches of the take-off location, although I never let it completely auto-land. I always cancel it and fly the last bit down manually.

You shouldn't need to calibrate your compass for such a small change in location. However, you should always check your compass and IMU in DJI Go4 before flying and ensure they are reading in the green.
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Thanks.
 
holtneil said:
Phantoms are known to do fly away you should calibrate the compass every time you change flight locations or it may one day head off to its last calibration point which can be miles away
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OOOPS! I had no idea! That wold not be good. Thank you. Will do.
 
holtneil said:
Phantoms are known to do fly away you should calibrate the compass every time you change flight locations or it may one day head off to its last calibration point which can be miles away
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Yes, they occasionally like to go off on their own hunting wabbits
 
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