Hello all,
I’ve got an issue when I switch from quadcopter modes like qloiter to fbwb. I am using a tilt rotor type aircraft. I’ll leave a link below to the .bin file, the ground video, and the on-board flight video. For some reason when I switch modes. The aircraft starts spinning clockwise instead of beginning to fly forward and transition to fixed-wing-flight.
I have looked at the log file but I’m so new at this I have to admit I’m not sure what I’m looking for to diagnose the problem. I tried reversing the yaw signal coming from my transmitter and that didn’t do much. Is there a parameter that I may have missed? Any help or advise would be greatly appreciated. Let me know if the link isn’t working.
Hey Dhanesh,
Thank you for a quick reply. There are two motors that rotate forward and act as “puller” motors in fixed-wing-flight. Upon switching to fbwb, I’ve observed that the two front motors do begin to tilt forward. but it seems to cause the vehicle to spin uncontrollably.
You are correct! I just saw the video, your quad motors are tilting in the same direction, instead, they should be in the opposite direction (as per the video).
Great Tip! I have verified that my rotors are tilting correctly and that the motors are spinning correctly as well. I am still unsure of where the problem may be. I am using a 2+2 comfiguration so only the front two motors are able to tilt. I’ll look through the documentation to see if I missed anything.
I watched the video showing the attempted transition and it looks like both tilt servos are stalling. The right one seems to stall just before the left one does. This is probably what is causing the plane to rotate in a clockwise direction. If you look at the 13 to 14 second frames you will see the right servo stops rotating at approximately 45 degrees and then the left stops at a little bit more of an angle. I don’t know what servos you are using, but you should be using High Torque MG servos.
Jamesjack,
Checking the servo travel is a good tip. I was able to check the sevo travel and it seems good. I have a quadplane setup with differential yaw so I think that is what you were suggesting when you said motor differential.
What I am noticing is a “toilet-bowling” effect. This has been a problem in the past for me and has come back up recently. I’ll include a link to my most recent crash data. I saw the toilet-bowling happening in qstabilize, qhover, and qloiter. At the end of the flight, the plane pitched down suddenly and crashed. Before the flight I made sure my motors were aligned, I recalibrated the magnetometer, I recalibrated the ESC’s, and I made sure my GPS unit was fixed tight. I even disabled the internal compass on my pixhawk to avoid magnetic interference issues. I’ve looked into the flight logs and telemetry logs but I’m not able to see anything out of the ordinary. I suspect the internal IMU is to blame but I’m not sure. I am desperate! I can’t seem to figure it out.
Interesting. It appears in my servo output screen in mission planner that ch7 and ch8 are disabled. This corresponds to a value of 0. setting channels 7 and 8 to 75 and 76 respectively would set those channels to tiltmotorfrontleft and tiltmotorfrontright respectively. According to makeflyeasy (the manufacturer of the plane) channels 7 and 8 should be set to zero and channels 5 and 6 should be set to 75 and 76 respectively. Am I understanding you correctly?
