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-   -   paper: Take-Back-Half Shooter Wheel Speed Control (http://www.chiefdelphi.com/forums/showthread.php?t=105965)

Ether 07-04-2013 13:53

Re: paper: Take-Back-Half Shooter Wheel Speed Control
 
Quote:

Originally Posted by tr6scott (Post 1258113)
The code is labview, more info from this link. http://www.chiefdelphi.com/forums/sh...d.php?t=113954

Doh. I remember our conversation now. I am starting to show my age. Sorry 'bout that.



tr6scott 07-04-2013 14:59

Re: paper: Take-Back-Half Shooter Wheel Speed Control
 
:) Me too. NP.

The Doctor 03-04-2014 22:14

Re: paper: Take-Back-Half Shooter Wheel Speed Control
 
I have found this to be an acceptable take-back-half algorithm:

Code:

cval -= (cval - goodval) / 2;
Where cval is the current value of [whatever] and goodval is the ideal point (what you want it to be at)

Code:

cval += constrain(-(cval - goodval) / 2,-max,max);
This also works, but is constrains the value to within a maximum speed, the variable max. Function constrain below:

Code:

float constrain(val,min,max) {
          return val>max?max:val<min?min:val;
}

This seems a lot simpler than the previously posted code, and I was wondering if they are equivalent?

Ziv 03-04-2014 23:29

Re: paper: Take-Back-Half Shooter Wheel Speed Control
 
Quote:

Originally Posted by The Doctor (Post 1369035)
I have found this to be an acceptable take-back-half algorithm:

Code:

cval -= (cval - goodval) / 2;
Where cval is the current value of [whatever] and goodval is the ideal point (what you want it to be at)

Where's the feedback here? How do you find goodval? The fact that you're setting cval suggests it's an output, and if you somehow knew the ideal output (namely goodval) then you wouldn't need closed loop control in the first place.

Now, if you instead have

Code:

cval -= (sensorval - goodval) / 2;
which seems to be what you were getting at, then what you secretly have is an integral controller (just the I from PID) with coefficient 1/2.

Ether 04-04-2014 12:01

Re: paper: Take-Back-Half Shooter Wheel Speed Control
 
Quote:

Originally Posted by Ziv (Post 1369059)
Now, if you instead have

Code:

cval -= (sensorval - goodval) / 2;
which seems to be what you were getting at, then what you secretly have is an integral controller (just the I from PID) with coefficient 1/2.

Yes.

And, just because it's an integrator, and its gain is 1/2, does not make it a TBH algorithm. The hallmark of TBH is the unique way that the output is reset at each zero crossing.




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