Our quad is not stable

Posted by Rafael Córdoba on June 6, 2013 at 12:33am

Hi! Sorry for making so many questions, but this is our first quad and we've lots of questions. We've tried to fly in stabilize mode, but our quad is not stable. Look at this video to watch what happens:

https://www.youtube.com/watch?v=U2lzR1kuW0s

I'm trying to modify the PID's params, but I don't know which of them do I have to change.

Thanks a lot for your help.

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Replies

  • Rafael Córdoba June 20, 2013 at 12:27am

    Well, now the quad is more stable than before, but it still obscilate. It's got a lot of vibrations and I don't know if it's because of  the frame, the motors o whatever. How can I fix this?

    Thanks a lot.

  • Rafael Córdoba June 12, 2013 at 3:30am

    Whit Tono's config it is more stable than before, but I still have to improve it a bit. What means the IMAX param?

  • Rafael Córdoba June 7, 2013 at 2:55am

    Well. I'm trying to tune it at the moment. Let's see if it works!

  • Pierre Dutoit June 6, 2013 at 10:57pm

    I have observed the same oscillations with my hexacopter at ground proximity and no change in the parameters are necessary.

    Showing your video i see the first seconds the copter is stable and the solution is to give more trottle to lift at about to 50 cm high and reduce so  the ground effect.

    You can test with an other person hold the copter horizontally  at about 1 m high and give about 50% throttle to see if oscillations are present. 

    Another usefull control is to measure at full throttle the rotational velocity of each motors to stay in the range + - 100 rpm.

     

  • Rafael Córdoba June 6, 2013 at 8:47am

    Thank you all. I'll try to read and tune all params and we'll see if it works or it doesn't. I hope it works 'cause we've had a very hard work building the frame, looking for help, etc.

  • The Sun June 6, 2013 at 8:34am

    I agree with those in the thread who have suggested tuning: as far as I can tell this is a case of horribly overlarge P values, or perhaps a slightly over-inflated D term. 

  • T3
    Richard Boyhan June 6, 2013 at 5:16am
    Below is Dave C. Tuning guide. It's a good read.

    http://www.diydrones.com/forum/topics/arducopter-tuning-guide
  • Developer
    Jani Hirvinen June 6, 2013 at 3:06am

    Well I would say that starting from small is not a good idea. As you just beging this hobby, go for bigger quad. Normal quad size is around 60cm from motor to motor. Smaller quads are a lot more demanding due their weight, size and extreme vibrations. 

    Best way to "kill" your quad no matter what size it is, is with vibrations. You need to make your quad as vibration less as possible and then it's easier to tune it. Even smallest vibrations on flight controller will make tuning and flying hard. 

    So first thing is make bigger frame, Second make it vibration less as possible. Again.. it should not vibrate. If you feel tinkling on your fingers when motors are running, for sure you will have problems. 

    Frames/Motors/Propellers always vibrates a bit so balance your propellers properly, put some anti-vibration tape under autopilot and so on.

    jani / jDrones

    jD-main
  • Charles lakins June 6, 2013 at 12:55am

    heres some help

    http://code.google.com/p/arducopter/wiki/AC2_attitude_PID

    http://en.wikipedia.org/wiki/PID_controller

     

     

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