[Intro Music]
I'm Joshua Bardwell
And this weekend I will be presenting
a PID tuning masterclass
at the New York City Drone Film Festival
on March...2017, since things live forever on the internet
uh, many of you wont be able to make that
and thats OK
because
it will eventually be posted online
I've made sure that I have permission to post it to my channel
So you will get to see that presentation
It'll be more of the same PID tuney-goodness that you're used to seeing from me
In the lead up to that though,
I have some video that I shot
and I shot that video to
use in the PID tuning masterclass.
But of course I shot
Lots of video talking about PIDs and soforth
So Im going to be rolling out that video
over the course of this week
and some other good stuff too, not just that
since I know not everybody is into the PIDs
and then leading up to that , uh, when I'll give
the final presentation on, uh, I think it's Saturday afternoon -
I should really check when it is -
Uh, I'll give the final presentation at the film festival
Ok so here is the beginning of that
Thanks for watching...enjoy
The first thing I'm gonna do
is I'm going to turn my P-gains way down
and lets get a look
at
what that looks like
looks pretty good, I think
And then also
lets turn the D-gains
all the way down to zero
so that we can - when we raise the P-gains later -
We'll see the effect of not having D
and then we'll see the effect of adding D in
OK
Now we're going to fly like this
and it's going to be hard to fly like this
But I think I can do it
But the copter is going to be really sloppy and
require a lot of stick input to get it to do what it needs to do
It's gonna feel really sloppy and imprecise.
see that wobble there?
if I try and do some precise flying like this
I'm gonna find it hard to do
it's actually not as I would expect with the P's this low
You can see there - the propwash handling is really poor
and that's the lack of D, I think, more than anything
there, see that?
see that soft oscillation there?
Right there. Those sort of lower frequency, soft oscillation
That's low P-gain
It's having a lot of trouble here.
It's still pretty flyable. I'm really amazed at how flyable it is
with the P-gains this low.
But you can see that we're getting those propwash oscillations
on sharper turns
If we do some flips and rolls, let's see what we get
Big, big bounce there at the end of the roll
Let's look at a flip
Big oscillation, multiple oscillations there. There again.
Soft oscillations there.
Um
You see the multiple oscillations at the end of the flip
not just one rebound but..
that was more like one rebound. But we also saw
multiple oscillations there
and that's usually indicative of
high P-gain
but because those oscillations were so soft
We also, we know - this is low P-gain
those soft oscillations are indicative of low P-gain
What I want to do now is - I want to start raising those P-gains up
And I'm not going to change the D-gains at all.
Let's just take them to three (30)
Now what you're going to see..
And I'm gonna leave yaw alone for now
I don't think yaw is going to be as visible
So we'll leave that alone.
Now I'm going to do the same sort of maneuvers
and let's look at the difference
here's some prop-wash
the prop-wash handling is already better
still a really big bounce there at the end of the roll
the bounce at the end of the flip wasn't as big
No, much better for the flip. A flip and another roll
Ooh, real problem with prop-wash there
the roll is getting a much sharper stop
but we're still definitely seeing some prop-wash oscillation though
Let's go ahead and raise this up again
and we'll put them at 40
we're gonna leave yaw alone
I don't think yaw is going to have as visible effect on the handling
mostly I think I tune yaw by feel
and I just don't think it's going to be super visible.
so...we'll leave that alone
Let's look a the prop-wash handling first
doing these...
...it's getting better. You can see that it's getting better
Let's look at a flip or a roll
Big bounce there and I got a battery critical warning
battery's just getting lower
that flip was not too bad
we seem to be doing better with flips than with rolls
that may have to do with the fact that this is a stretched-X copter
yeah big -
do you see how the rebound; the oscillation after the rolls
is getting, I would say, it's getting sharper versus softer
Um, it's getting higher frequency
As you raise the P-gains, you'll start to get those sharp oscillations
coming out
Let's keep raising them
Ok
So now we're at 50. I don't think we've flown this one so we'll go ahead and fly it.
Let's look at the prop-wash first
The prop-wash handling is continuing to improve
the prop-wash oscillation is getting higher frequency and smaller magnitude
so instead of BIG soft oscillations - let's do - let's do a drop
BIG soft oscillations...
that was pretty good
no oscillation there on a drop and raise the throttle
let's look at a flip and a roll
Big bounce there still
I don't think that's gonna get fixed until we add...
Some D-gain...big bounce there as well
yeah
those are getting, um
uh, sharper
smaller magnitude
and higher frequency
and as we continue to raise P
that's gonna continue to happen
and we're going to see why we need D-gain
Why P alone cannot fix it
let's continue to raise the....
the P-gains
Now we're at 60
Now, do you see how that oscillation didn't die out as fast?
But kind of cascaded on itself?
See how it keeps going until I drop the throttle?
That means our P-gains are getting too high
It's gonna get more and more unsettled
See, it's just continuing to do it. It's not...
It's not settling itself but it's feeding back into itself
and it can't...can't control it
it can't let the oscillation die out on it's own
Pretty good there on the drop. But in the prop-wash scenario it's really having trouble
Let's look at a flip and a roll
Yeah. There. Do you see that?
That's high P-gain right there. The P-gain is too high
and you see. It's just all the time
...not so much on flip though. Flips have been better than rolls, generally
Oh yeah. Oh yeah.
There. So it's starting to get...
...not as controllable. Isn't it?
these oscillations are sort of...
happening all the time. The copter is getting harder and harder to control
I'm having to really manage the throttle
I'm having to back off on the throttle
in order to keep the oscillations from cascading out of control
let's raise it a little more just so we see what happens as we get...uh...too much
If I raise the throttle in a straight line, I don't get any oscillation
but any time I do sharp turns...
the oscillations start to come out
flips and rolls
oh! there was an oscillation there
just raising the throttle gave me an oscillation
see?
that's excess P-gain, that's what it looks like - oh yeah, oh yeah
I'm constantly having to back off the throttle to let those...
tho let those, uh, oscillations subside. The're not subsiding on their own are they?
If we look at a flip, how are we doing on a flip?
Oh. See I can't even punch out for a flip now
because these oscillations are just too much
if we just look at...a little throttle..a little blip
you can hear...
there is the oscillations there
yeah...this is excess P-gains right here...this is it
so, let's land now
this is only gonna get worse. So I'm not gonna keep going
Now. What I could do is back the P-gain off..
But, um..
But I'm not gonna do that...because
What I can do instead is add D-gain.
and we've got zero D-gain
and D-gain will have the effect of -
You think of D-gain as damping, but it's not really just damping
...let me fly this one back in because...we have 15 volts...
you think of D-gain of having the effect of damping the P-gain. People think "d" equals damping
D-gain doesn't just damp the P-gain but it does have the effect of
sort of taming the P-term oscillations
it also has an accelerating effect
though what D-gain actually does is, it accelerates
both directions - it accelerates when the PID sum is growing
it makes it grow faster. But when it's decreasing it makes it decrease faster
And the decrease faster is the one that is sort of most noticable
So let's go ahead and save this...
..and we will now start adding some D-terms