Hay Guys...
I am using Pixhawk with 3.3.3 quad. We use factory PID values. The first flight was in POS HOLD mode at an altitude of 7 meters. There was a slight wobble and jerk in the quad. We flew for about 4 mins. The next flight was the same POSHOLD mode but found the is slightly stable and jerk was reduced compared to the first flight. Then the third flight, We could see much difference from the first flight. The quad was even more stale and jerk was greatly reduced. For each flight we power cycle the quad.
We had observed this same scenario next day also. the stability of the quad gets good for successive flights. Is there any offset values are stored for each flight? What could be the reason?
Replies
Thanks Vesselin Goranov... that a good idea, which I could try....
When I'm testing new drone, especially large one, always doing tethered flight tune. This ensures good stable flights, and no risk to break the new "bird". Moreover I'm living near the airport, where test flights are not possible.
This way you adjust the PIDs well and get the correct values for different loads, camera, etc.
The tethered tuning can be done outdoors, using bungee between two poles or trees.
The procedure is well described here.
I have noticed this myself. I don't know what it is but I swear it's not just my imagination. Perhaps the first flight the gps takes longer to acquire than subsequent flights. Or the compass when set to auto adjust or what is it?.... auto declination or something.... Anyway maybe that's it. So after a few flights the compass settles down. But I agree after 3-4 flights it just seems better / more stable.
As others have said starting out in stabilize or alt hold is better because there is less risk that it doesn't do something unexpected because it doesn't use the gps as much... or if at all.
Thanks Harry Courter.... Couple of months ago,we start with stabilize mode and change to pos hold or auto. But recent times starting with pos hold, which could take off with less jerk..... We have never flew with loiter mode. Can you explain me why do start with stabilize alt hold and loiter. Is there any reason behind that?
Autotune looks like a nightmare...We are in the process of building few more drones, after that autotune will be done.
We actually power cycle the entire system after each flight... If it resets the parameter, the second flight should also be jerky one...... but we dont see much jerk in second or third flights...
Harry Courter said:
Hay Philip... 3.3.3 firmware is working good. yet we had some crash with same firmware in auto flight mode and in stabilize mode, we have checked logs, don't know what could be the reason. For each firmware update there are lot of new parameters which affect the flight. Firmware update might be another iteration. We have to test with latest firmware in subsequent time....
Your first flight was totally in "position hold" mode? You need to start with stabilize mode, then move to alt hold mode, then to loiter. Only in this order can you really judge performance.
Until you succeed with completing the autotune routine nothing can be clear.
To respond to the question, Value "I" is adjusted during flight to compensate for a consistent error not corrected by "p" caused by something like a steady cross wind, This is why we can set "I max" value, to avoid the system setting this value to high.
However this is resets for each flight.
first comment, why would you fly with 3.3? move to release, or 3.5RC2.