PID Controller

[Fizyk]

PID can do the same as delta, when you use only P and D (I=0). I is used for extra stabilization, for example: if you use only P and D for holding altitude, it will always be a bit below the desired altitude - adding some I gain can eliminate this. It's just math

Anyway, can someone check the lua file changed by me (3 posts up) and maybe add it to UWSVN, if it's confirmed that it works?

[tuusita]

1.5 month BUMP!
Sorry about that. :blush:

Fizyk, to me it looks like the PID does seek to the new setpoint smoother than before.

But is there a way to make it properly follow a constantly changing setpoint? For example, a steady climbing setpoint on world Z axis makes it over/undershoot it constantly. It over/undershoot gets even worse if I change the rate of climb.

Hmm, come to think of it. I think I'll test a 'hold velocity' method rather than a 'follow changing coord' method.

I'll post my findings here:
EDIT: It seems to work. I can get an object to hover pretty darn perfectly when using GPS (z coord) and a delta gate(for up/down speed) Although there seems to be problems using the speedo, but it matters not since I'm now confident I'll get it working for my intended purpose.

[Pyroclastic]

Bit delayed but I just started reading this thread today. But I did a quick conversion on 3dfactor's E1 to make it an E2. I haven't done much testing, but it should work. All I had to do was shift a few if statements around and add some persists. So here it is:
[highlight=e2]
@name PID Gate E2
@inputs On CurValue GoalValue P I D Dcut Ilim Omin Omax Reset
@outputs Value
@persist Time Error Pt It Dt
@trigger On Reset CurValue GoalValue

interval(50)

if (first()) {
Time = curtime()
It = 0
}

if (!clk()) { exit() }

if (On) {
Time = curtime()
Error = GoalValue - CurValue
Pt = P * Error
Dt = ($Time > 0 ? ($Error/$Time) : 0) * D

if (abs(Dt) < Dcut) { It += I * Error }
if (It > Ilim & Error > 0) { It = Ilim }
if (It < -Ilim & Error < 0) { It = -Ilim }

Value = Pt + It + Dt
Value = (Value > Omax ? Omax : Value)
Value = (Value < Omin ? Omin : Value)
}

if (!On) {
Value = 0
Time = curtime()
}

It = (Reset ? 0 : It)
[/highlight]

[tuusita]

Quick corrections on your code Pyroclastic.

Line 14:
if (first()( {
The parenthesis in red is facing the wrong way.

Also, Out variable "doesn't exist". Added to outputs.

Now it's time to test it.

EDIT: Oh, hang on. Looking at your code AND thinking about it this time, if Value is the output of the PID, shouldn't you change all the references to Out into Value?

EDIT: Hmm, I suppose it does handle the change in SetPoint (or GoalValue in your E2) a bit better. Needs more testing to be sure, but I'm dead tired at the moment. 10hr work day does that sometimes... :P

Thanks for the E2 PID code, Pyroclastic.

[Pyroclastic]

Yeah, I noticed those as soon as I loaded it up, I did the translation in notepad. I edited my post with the corrected and working version (I did test this one).

[ningaglio]

where is the dupe file, i cant find it

[TomyLobo]

so you can steal that as well, ningaglio?
great reason for thread necromancy...

[Nicolai1]

Ningaglio has succesfuly bumped a pretty goddamn old thread...
*Facepalm*

[Ryusho]

Great..so I downloaded a 'obsolete' tool because someone necrobumped it? great >.<

[krazyfool]

Can some one explain to me how to use this. I currently use delta and i heard this was a good alternative. For some reason i just can't grasp how to use it. Any help?