Purchased a 2nd hand P3s which is crashing when it decends in auto flight R-T-H. The first 2 times I thought it was me or the wind, but it has happened 4 times now with no hands on the controler and no wind today. It decends to about 20 meters and just starts swinging out of control, before making a rapid decent. I tried putting power on today once it started but made no difference. It doesn't happen all the time and R-T-H works just like I expect it to otherwise, rises to preset hight, beelines for home and starts to decend. Am I missing something?
Previous experiance on P4P, Inspire 2 and Matrice 600 and haven't seen anything like this.

Only thing I can think of is maybe you lost GPS or it became intermittent as you descended due to the elevation mask which caused it to drift and correct as it descended the last 20 meters...

The P3S is limited to US satellites, unlike the other ACs you mentioned above which would include Russian satellites

What happens when you cancel RTH?  

That's the real crux ...

Cancel RTH and land yourself ... Auto Land in RTH is not a good idea ... its only good really as a last resort.

As to why your P3S is not good in that last descent ? What is the area you are landing in ? Maybe it has some magnetics ? But I assume you are landing in same spot as you take off from ? Are you doing Compass Calibration each time taking off or did it at this spot originally ?

1. Compass calibration is only needed usually once or later when absolutely necessary.

2. If you calibrated at that spot - it could be that its not a good location and your AC is having trouble when its on RTH nearing the spot ... who knows ?

GPS is good enough on its own - having Glonass is only 'icing on the cake' in fact ... so its not that. Again if you are returning to take off point - you would have known if it was shielded from Sats at take-off.

I would find a nice clear quiet spot out in the country well away pylons / cables / structures and test it again ... see what happens ... if it was mine - probably do a calibration there to be sure I have a good one. No need to calibrate again after that.

Nigel

Have you tried calibrating the IMU on a flat surface?

djordan2 Posted at 2018-3-4 08:03
Have you tried calibrating the IMU on a flat surface?

can I add :

Absolutely flat level surface checked by spirit level ? And done as cold as possible BEFORE AC warms up.

Nigel

Sorry to read on your post about the issues you are having with the drone, it may be related to poor GPS signal or the strong interference and so on, if the drone has been damaged, we recommend to contact our support team to start a ticket and send in the drone for data analysis if it is still in warranty period. We will do our best to make it clear.

Hello Everyone and thank you for your input.

I've calibrated the GPS at all of the launch spots, and its landed at all spots RTH OK.
There is iron stone around, but that should be constant interference.
Calibrated the IMU, not dead level, but read OK afterwards.
There are power lines within 100m, transformers and solar inverters, but no interference showing on takeoff. And it's in the country.
When I've cancelled RTH and put full power on I wasn't able to get control. I got some horizontal control on a previous crash.

Mindy, it's a 2nd hand drone that has been cleared of its data from what I can tell with a first gen controller. I'm doing my commercial RePL licences in Australia and got it to practice at home before investing in a new one.
I'm still not sure how to up load the telemetry for you and I still need to edit the 2 x videos I've got down to the last minute or so.

The only external damage has been the vibration plate, which has been replaced & 2 sets of blades. I suspect the previous owner crashed as it came with a spare camera.
Happy to provide the data though.
I appreciate RTH is a last resort and I should be doing more Atti flights and landings as recommended by my flight instructor.

Your thoughts are appreciated.

Thanks for the clarification. I'm afraid that the performance cannot be ensured after the crash. As Mindy mentioned, it is suggested to start a case and send the unit in for a fully diagnosis: https://www.dji.com/support The local team will take care once received the package.