Hi all,


Yesterday I went to the field to do my 1st flight and autotune the PID gains of a custom frame quadcopter.
The configuration is 'X' and I use Pixhawk with APM Copter V3.3.3. 30A ESCs with D3530/14 motors, 7x4'' 3 bladed props and a 4S 5000mA LiPo battery. I attach a photo of the copter. I did all the needed calibrations and checks through the Mission Planner 1.3.39. The GPS signal was strong outside and after a preflight test I took off the copter in stabilize mode around 1 meter from the ground and I moved it around some meters with my Taranis telemetry system. The flight for some secdonds was smooth enough but suddently the copter started to oscillate around the roll axis without being able to stabilize until it hit the ground. This happened before turn to Alt hold mode and switch the pre-configured channel 7 for the autotuning of the PIDs.

I went through the log file and in ATT signals I see the desired roll and pitch to be almost zero but the response from the pixhawk is violent oscillations. I can not see any hardware error prior or during the oscilations. I believe that the PID default values probably made the response unstable. I do not have much experience to extract any other valuable information from the log file. I attach it for reference. Is there a recipy to put some other than the default values in the PIDs before the performance of the autotuning in order to avoid these severe roll oscillations? For instance to reduce the default 'P' values?
I would be grateful for any help.

copter.jpg

87 8-8-2016 7-11-58 μμ.bin.log

copter.jpg

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