twitching

O

oilee

Member
Im new to the hobby.
This is my first build.
I built the mr steele alien per his you tube build.
It has a kiss pdb, kiss fc and kiss 24 esc and 2345 kv motors and 5x4.3x3 props.
I have it to the point where i can hover it.
But it twitches. not to the point where i cant keep it hovering but it isn't running smooth.
I soft mounted the fc and removed the vtx to see if that helped . It did not.
I ran it with out the props and i didn't notice any twitching.
Not sure what to do next. I should have got a rtf.
Hope someone can shed some light.
Till i can figure it out back to the sim
 
Have you messed with any pids.
Try a board reset but don't load any backup settings. Just set it up again.
You should also check all the solder joints for that motor. Maybe Reflow them if possible. This is why everytime I connect & solder a wire I check it with a multimeter. Sorry I don't run kiss so my knowledge is limited.
In bl-heli are the throttle low & high points the same.
 
I have the pids adjusted per rotor riots recommendations for starting out.
If you mean re loading firm ware into the fc, i tried that and no change.
I will check the solder joints and use multimeter, I havent done yet.
From what i understand so far kiss has a thing called kiss gui .
this is where i can adjust things , configure, data output,rates ,tpa, esc flasher.
I followed a tutorial and think i have it set right.
Thanks for the help
 
Most yaw and mid throttle twitching is noise induced from voltage spikes. Flight controllers such as the Lux and Rev6 Naze which use the MPU 6500 gyro chip are especially sensitive, not sure what the Kiss uses. But I'd focus on noise reduction, start out with simple stuff such as are all the screws in your frame tight and are any of your props/motor shafts bent. You stated that your FC is soft-mounted but you could also do the same with the motors. BUT the biggest noise reduction can be had by simply soldering a 1000 uF 35V low ESR capacitor onto the main battery pads. This will also have a nice side-effect of cleaning up any crap in your video feed. I use these ones.

http://www.readymaderc.com/products/details/capacitor-1000uf-35v
 
Just an FYI. Your mileage may vary :rolleyes:

When one of my RTFs "twitched" it acted like it was fighting intermittent gusts of wind. And there was no wind.

Turned out it needed a Compass Calibration.

I generally fly around home. Out in the country, so I rarely mess with compass.

Good luck!
 
IMG_20170621_225309292-768x1367.jpg the green object is low ESR.
You can place them here or the motor side of the esc. You can soft mount an fcb but you can't soft mount motors. You can buy fancy coloured whatever but you can't escape the fact that the frame screws & motors are one & the vibration is still going to travel through the screws. So I think soft mounts make it worse as there is that little room for give. Motors have vibration for a reason, unbalanced props, bent shafts o_O or bells. Whichever needs fixing, props or bells.
I never even looked at the kiss GUI so I'm stumped there.
 
mozquito1 said:
View attachment 3573 the green object is low ESR.
You can place them here or the motor side of the esc. You can soft mount an fcb but you can't soft mount motors. You can buy fancy coloured whatever but you can't escape the fact that the frame screws & motors are one & the vibration is still going to travel through the screws. So I think soft mounts make it worse as there is that little room for give. Motors have vibration for a reason, unbalanced props, bent shafts o_O or bells. Whichever needs fixing, props or bells.
I never even looked at the kiss GUI so I'm stumped there.
Click to expand...
oooh, there are a lot of developers out there who would totally disagree and would disprove that statement
 
RENOV8R said:
oooh, there are a lot of developers out there who would totally disagree and would disprove that statement
Click to expand...

:rolleyes: Agreed ! .... Soft mounted motors when considering vibration transmission through the screws may SEEM contradictory, but
it's easier to understand the benefits when you consider this:

Without soft mounts there is a broad solid surface to surface contact area (motor against arm) that easily transmits any vibrations.
There is no "give" at all and vibration is transferred through the broad contact area as well as the screws.

With soft mounts that broad surface area is cushioned AND that cushion also allows the screws to (in effect) "come off of contact"
from the arm when the cushion gets compressed by any vibratory motion TOWARDS the arm. The net result is that the broad surface
area of motor to arm contact is virtually eliminated with respect to vibration transmission effects, and the screw's transmission effects are
reduced by approximately half (given that they still have hard contact ONLY when the vibratory action is PULLING them harder against
the arm.

In summary, virtually eliminating the broad surface area contact (with respect to vibration transmission effects) combined with
eliminating one of the only two directions for screw vibration transmission effects GREATLY REDUCES VIBRATION TRANSMISSION. :)

There's no valid argument against eliminating the SOURCES of vibrations however,
but that does not preclude the benefits of soft mounting motors. ;)
 
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I'm actually surprised that there hasn't been more advancements in this area. When you think of it we are using notch, LP, D-Term, Kalman, FIR, PT1, Biquad, all these different filters to reduce the noise the motors are producing. They work quite well at what they're intended to do but the bottom line is the amount of filtering we induce is directly proportional to the responsiveness of the gyro. If we can reduce motor vibrations. even a bit, we are eliminating the problem at the source rather than using filters as a bandaid fix. Those tpu or silicone soft-mount plates do work, I've seen the results in BB logs, I think the key is to use one on each side of the arm, not just one between the motor and the frame. Also use blue Loctite so you don't have to screw 'em down super-tight. Less noise + less filters = more awesomeness
 
Hey whatever floats your boat, I would like to see the logs.
But you still can't escape the fact that the screws attach both plate & motors.if you have soft mounts both sides then there is no proper adhesion of the plate to motor. Therefore having give. As for not screwing the screws down tight & hoping loctite suspends them without coming loose. o_O
So unless anyone can show me evidence,
Otherwise I think it's just a selling point.
If you got vibration in a motor, it's going through the screws. Fact. Loctite'd or not
One of my first quads was beat up, slightly bent motor shafts or bells bent fibreglass arms. Vibration was like a hand drill in the hand. but it flew because the fcb was soft mounted. The only way to reduce motor vibration is to keep ontop of the motors.
Either look after them or replace it, if it's bent or an unbalanced prop. To be honest I've never had problems with vibration like the OP suspects. It would not effect 1 motor from the gyro. I know what would though, a very close short or somthing not being solderd properly. A slight connection.
 
RENOV8R said:
I think the key is to use one on each side of the arm, not just one between the motor and the frame.
Click to expand...

I've seen arguments both for and against cushioning both sides.
Of course loctite IS A MUST, otherwise you're reducing the effectiveness of the cushioning by tightening the screws enough to be fully secured.

The gist of it was if both sides are cushioned then, by allowing travel both toward and away from the arm, while the vibration transmission
isolation becomes enhanced the possibility of harmonic oscillation increases ... Moz makes a good point in that the eliminating the source
of vibration is a preferred action, but that's not alway an easy thing to determine or remedy.

Another thing worth mentioning regarding using filter capacitors:
Having a large value cap added in does absorb voltage transients, however it does little to block high frequency noise.
There are specific responses of capacitor values to specific frequencies, and just throwing a large cap will not address those higher freqs.
In fact, a smaller value cap has a greater effect on higher frequencies than a larger one, with the specific value to address the particular
frequency being derived by some mathematics.

My general recommendation is the use of POLOLU products to clean up any and all issues regarding voltage sources.
You just can't beat their cost, weight, form factor, performance, and over all value when it comes to such matters.
This coming from some one who can design and construct their own surface mounted component custom circuits boards. ;)
 
:rolleyes: ... Moz, the whole point is "having give" as you put it.
As for the screws, I've addressed that aspect of it too .... perhaps you didn't fully read my post?
I agree that getting rid of the cause of the vibration is the best resolution but, like I also said, it's not always
such an easy thing to trace down to the source.
 
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