Discussions

Opinion on flashing ESC's for multirotors

Posted by Vincent Mees on October 13, 2011 at 12:53pm

I would like to hear some opinions on flashing ESC's

 

I've been reading about this over at rcgroups

http://www.rcgroups.com/forums/showthread.php?t=1513678

 

The main advantages, from what I read, would be that:

-the speed between controler and ESC is 8 times faster

-no more need of ESCcalibrations

-no more programming of ESC with programming card or TX

 

I'm using the plush 30A ESC's with the Atmega8 so reflashing it wouldn't be a problem.

 

Could this give improvements to the overal flight stability of Arducopter whenlooking at the update speed? 

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Replies

  • Martin Szymanski January 9, 2012 at 5:39pm

    There will always be some sort of latency. It can be the motor prop combination with the airflow.

    Maybe the frame is heavy?

    The response rate ot a controller should be fast as possible.

    There is a point of dimminshed return though.

    A PID rate gain can adjust to a frame.

    However if the frame is physically designed to move slow it will.

  • Duy Pham January 9, 2012 at 5:08pm

    Hi Jashon,

    In the code of the ACM, 

    ((timer - fast_loopTimer) >= 5000)

    is this only need 5ms rate from ESCs?

    Could we change it into 2000 for 2ms response?

    Thanks,

    -Duy

  • kolin January 9, 2012 at 1:04am

    Hi,

    Back in days when KK board was only DIY, I had to reflash my TowerPro 18A to work with it. Without it, my tricopter was unflyable. That ESC really didn't like fast PWM. Btw esc cpu was not locked, so I made backup.

    Here is a proof, tested with futaba 401 gyro in DS mode (about 300Hz update rate)

    https://www.youtube.com/watch?v=c-Y6dyR8YFQ

  • Developer
    Olivier ADLER October 14, 2011 at 7:00am

     

    This will not give you big improvements.

    The APM output is optimized to artificially bypass the ESC low pass filter (Using Fast PWM). This is enough. The response time is more limited by mechanical inertia.

     

    Changing the ESC firmware is a quite difficult task. I did have a discussion about this with one of the firmware hacker who wrote a modified version and decided to not modify my ESCs because of the very low enhancements compared to the amount of work.

     

    The best efficient change you can do if you want faster response time is going to variable pitch props on each arm.

    Unfortunately this translate to a more expensive and more fragile setup with added weight because you'll need one more servo on each arm.

     

  • 100KM
    u4eake October 14, 2011 at 4:59am

    Problem for me is that there's no turning back.  You can't put the original firmware back I think, at least I haven't seen it anywhere.  So if I do it on my hexa, and it doesn't work out, I've wasted 6 esc's.

  • Developer
    Jason Short October 13, 2011 at 1:38pm

    8x is terribly unrealistic. There is an 8 step filter on the esc, so within 4 400hz iterations, you're half way there. 8x would imply it takes 8 times longer for any update at all.

    Jason

  • Björn Pettersson October 13, 2011 at 1:03pm

    Done this, (jDrones 20A ESC's) so far the most noticable difference is the quiteness, no high pitched scream, no klicking sounds either. Weather has been to bad to know if stability is better or worse (no flying at all).

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