Having trouble maintaining controlled flight

Hi all,

I've been taking my quad out for testing lately and I've run into a few issues when trying to fly it.

Firstly, I'm finding it very difficult to keep the quad in roughly the same spot. Whenever I get it in the air it always seems to be drifting quite quickly in some random direction. The quad itself is stable and flying without oscillation, so I think I've got my PID control values tuned fairly well. I'm using fairly cheap ESCs (these ones: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6460), is it possible they're not all responding the same way to throttle commands? Or am I just a terrible pilot?

Similarly, I have trouble keeping it at a constant altitude. Even when I have Altitude Hold engaged the quad will sometimes rapidly descend when I haven't touched the throttle.

Another issue I've had is maintaining the quad's heading. Once in flight the quad will begin yawing rather quickly, which makes it quite difficult to control. I have the magnetometer, I've calibrated it's offsets in the CLI and verified that it's working in the Configurator.

GPS hold seemed to work for a little bit today. That is until I tried to alther the quad's heading, then it banked steeply and rapidly descended.

I've verified that my RX is trimmed correctly and the accelerometers are initialised properly.

I'm not sure what else to try. Any help/input would be greatly appreciated.

Cheers,

Chris

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • Thanks for all your responses. Most of the issues were probably caused by me. Turns out I was wrong when I said "I've verified that my RX is trimmed correctly and the accelerometers are initialised properly".
    The transmitter trim values have a habit of changing, or simply no long being correct between flights. I've found it's a good idea to check the TX trims in the configurator before each flights.
    Also, I was also mistaken when I thought I'd initialised the accelerometer offsets correctly. I initialised them with my quad sitting on it's landing gear, but it turns out my quad's gear isn't quite level. To get it perfectly leve I put blocks of equal height under each motor, so that the quad was resting on the blocks. Then I initialised the offsets. It's been flying pretty level since then.
    I still have the yaw issues, but apparently things will be better in the next code release. Here's hoping.
  • I initially had problems wit the bullet connectors. Seems far away from the issue you seem to have however once hard wired together, I have had no problems with the stability (no more uncommanded death rolls!) I also mounted the boards between two layers of soft foam, maybe the vibrations were affecting the IMU's? Anyway, I think they  helped.

    However, I too have the heading hold issue, I thought it was heading lock enabled? Anyway, I set my rudder rate way down low (50%) so I need full stick to yaw it with authority. just small tweeks left and right keeps heading and gives me time to respond. Also, some "pool noodle" foam skids help me sighting the front and back:) I fly in X form as I want to make a plane like  fusalage later. But for now, Im having fun getting stick time up, indoor flying helping out a lot. It helps with the confidence and now I use it to do parachue tests without the need of a plane or conventional heli. Just shoot it up high and release the chute and beat it to the ground for the next one. Small things amuse small minds:)

    https://www.youtube.com/watch?v=-hxEV3ASAAY

  • can you check the magneto heading in flight? do you have Xbees?
  • Ok, I may have jumped the gun a bit. I just checked my RX trim in the Configurator and it looks like my RX had forgotten it's trim settings. I guess this is something I should check before every flight!

    I just flew it again and it looks like the yaw and altitude issues remain. It looks like the quad wants to yaw to a given heading, when I point it in another direction it returns to its previous heading.

    Chris
This reply was deleted.

Activity

Neville Rodrigues liked Neville Rodrigues's profile
Jun 30
Santiago Perez liked Santiago Perez's profile
Jun 21
More…