On Tuesday 18 December 2012 19:08:42 andy pugh did opine:
> On 16 December 2012 22:46, andy pugh <bodge...@gmail.com> wrote:
> > It wouldn't be all that hard to make a linearisation curve component.
>
> And it wasn't. Put the following in a text file called
> "lincurve.comp" then sudo comp --install lincurve.comp.
>
> component lincurve "one-dimensional lookup table";
> description """Performs a 1-dimensional lookup and interpolation. The
> x-val parameters must be monotonic, though identical adjacent values
> are allowed. (for example 0,0,0,10) for a 4-element curve. For input x
> less than the lowest xval the y-val of the lowest is returned. For x
> greater than the largest x-val the yval corresponding to x-max is
> returned (ie, no extrapolation is performed. """;
>
> param rw float y-val##[16:personality] "output values";
> param rw float x-val##[16:personality] "input values";
>
> pin in float x "The input value";
> pin out float y "The output value";
>
> variable unsigned i = 0;
>
> option extra_setup yes;
>
> author "andy pugh";
> license "GPL";
>
> function _;
>
> ;;
>
> FUNCTION(_){
> double f;
> if (x >= x_val(personality-1)) {
> y = y_val(personality-1);
> return;
> }
> if (x <= x_val(0)) {
> y = y_val(0);
> return;
> }
> while (x > x_val(i+1)) { i++;}
> while (x < (x_val(i))) { i--;}
>
> f = (x - x_val(i))/(x_val(i+1)-x_val(i));
> y = y_val(i) + f * (y_val(i+1) - y_val(i));
>
> }
>
>
> EXTRA_SETUP(){
> if (personality > 16) personality=16;
> return 0;
> }
Please put this into the hal repo andy, I think it can be very useful
indeed. I think it will need some man page dressing up, unless that file
is nothing more than a CSV list. Adding that comment would seem to be
sufficient to me anyway.
But as I said on IRC, a 10k resistor in series with the signal from the C41
to the FC250J's center arm of the pot terminal worked wonders for the
linearity of control vs speed. I actually have something I can use. Needs
some fine tuning of course but it works plus or minus 1 rps at any speed
now.
Cheers, Gene
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene> is up!
The chief danger in life is that you may take too many precautions.
-- Alfred Adler
I was taught to respect my elders, but its getting
harder and harder to find any...
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