I would like to hear some opinions on flashing ESC's
I've been reading about this over at rcgroups
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?
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).
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.
I believe the filter is gone with the firmware hack.
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.
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.
Another advantage of variable pitch is that it does avoid spending energy to accelerate the propeller each time a thrust modification is needed.
Using governer mode with Heli ESCs, power consumption should be lower with variable pitch.
It should give as well a bit more lifting capacity (and max flight speed) because of the adaptive blade angle giving the possibility to use larger props.
Here is a setup that can be quite easily fitted to a multi :
just the noise reduction does make it worth as far as I am concerned. the fixed calibration is another bonus.
ESC's can be found at reasonable cost
And yes, I bricked one.. lol
Test flew with my flashed esc's for the first time today. Made the mistake of changing more than one thing at a time so I can't say if it is better or worse (stability wise) as I upgraded to 2.0.48 on my arducopter since last I flew it.
However, it is now very quiet, i can only hear prop noise as it is now, no hight pitched motor whine. I can not say I have found any negative aspects so far exept my one bricked rc-timer esc.. (I messed up fuse setting a bit lol).
It was worth it, no doubt.
Version 2.0.48 does use normal fast pwm, there is less jitter on output. A part of your observations (less motor noise) does certainly come from here.
What about your battery consumption with the new ESC firmware ?
Can't say anything about consumption (have not made observations about fhat yet) the noise bit was very aparent before I upgraded to 2.0.48 (tests in living room). I shuld reconnect my Jeti amp sensor, I had just over 12 amperes in hover before this.
I did not tried 2.0.48 yet, but i think it will ask a bit less current for same thrust, because there is less jitter on the outputs.
I've seen at least one user in a forum that did upgrade his ESCs and did report higher current consumption, because without ESC low pass filter the current demand is not so smooth.
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)