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Sep 27, 2014, 09:36 AM
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Pixhawk Yaw Rotation Problem


Hello, I have been testing with my recently acquired Pixhawk Autopilot for my Quadcopter. Here is my current components on the flight vehicle:
Frame: HobbyKing H-Copter H4-650
ESC's: RCTimer 45A NFS/Opto ESC
Motors: RCTimer 5010-620KV
Propellers: 10x4.5''
AP: Pixhawk PX4FMU
RC Remote: Spectrum DX8

We used QGroundControl to load the TBS Discovery Frame (H-Frame) configuration onto the Autopilot. We calibrated the ESC's and have tested the response of the system similar to that mentioned
in http://diydrones.com/forum/topics/ar...r-tuning-guide . We then flew the Quadcopter with the default gains of the TBS H-Frame and it rotated about the yaw axis continuously.
We then saw that as the throttle increased the built in magnetometer of the Pixhawk started seeing a slight rotation due to EMI, thus we thought it might be compensating for it. After viewing
https://groups.google.com/forum/#!to...rs/TbXFZf4EKDc , we adjusted the input to the Kalman Filter
EKF RC2 100 -> 1000000
to try and eliminate the interference. The problem in yaw still persisted.
The maximum attitude angles were adjusted accordingly but the response in pitch and roll seemed suitable for flight.
MC_MAN_P_MAX 35 -> 15
MC_MAN_R_MAX-35 > 15
However, when flown the Quadcopter continued to rotate about the yaw axis almost in a cyclic nature.

Initially, we thought it was the ESC's calibration that was a problem, we re-calibrated and the problem persisted. We then thought of increasing the proportional gain P for the Yaw Rate and the Yaw to try and compensate for yaw disturbance faster, the behavior remained the same after the flight test.
YAWRATE_P 0.28 -> 1
YAW_P 2.8 ->10
YAWRATE_MAX 120 -> 10

We then limited the max manual angles as a last attempt:
ACRO_Y_MAX 120 -> 10
MAN_Y_MAX 120 -> 10
MAN_P_MAX 35 -> 15
MAN_R_MAX 35 - 15
But the problem is still present. Please could anyone help with this problem. I thought it should work straight out of the box. I forgot to put the Micro-SD card in the APU to log the data during testing, so I do not have data but I will attach a video shortly.
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Sep 28, 2014, 10:16 AM
Registered User
Thread OP
Here is the link to the problem experienced during flight.
px4fmu h4 quadcopter (2 min 7 sec)
Dec 02, 2014, 10:59 PM
Registered User
Hi, you probably fixed this issue by now, but I'll reply just incase.

I had something similar and fixed it by setting the frame to "Quad X" in Qgroundcontrol, however you have to swap all the props and motor directions too as stated here: http://copter.ardupilot.com/wiki/com...d-quick-start/

Hope this helps.
Dec 03, 2014, 08:48 AM
The coolest dude around
If you still can't figure it out try and get the compass away from the speed controllers as much as possible. For instance buy or create a gps stand. I had similar problems until I did this.
May 21, 2015, 08:06 AM
Dave2099
dave2046's Avatar
Hi did you work out what the problem was? I am having the same problems with my octocopter and can't figure it out


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