On 29 May 2013 13:24, Les Newell <[email protected]> wrote:
> My HAL component used a simple lookup table that mapped spindle angle to
> X position.
After much messing about I found the maths to be fairly simple.
Here is the comp, it goes in between the axis.0.motor-pos-cmd and the
PID/stepgen.
It needs connections to the spindle position and the current radius
and tool offset (halui holds this).
It knows how to lie about position feedback to prevent f-errors.
If the facets pin is > 2 it tries to make a polygon. Handy for those
home-made pentagonal allen keys and matching bolts :-)
component polygon "Add a spindle-position related offset to an axis
for polygon turning";
pin in float encoder-pos "encoder position, should be scaled 0-1";
pin in float pos-in "the input (motor position)";
pin in float pos-relative "The commanded position, used for calcs.
halui.axis.N.pos-relative";
pin in float tool-offset;
pin in float facets = 0 "the number of facets required";
pin out float pos-out "the modified position request";
pin in float fb-in "position feedback from joint";
pin out float fb-out "position feedback to motion";
function _ ;
license "GPL";
author "Andy Pugh";
;;
#include <rtapi_math.h>
FUNCTION(_) {
float f, d;
if (facets < 3) {
pos_out = pos_in;
fb_out = fb_in;
return;
}
f = encoder_pos - floor(encoder_pos * facets)/facets - (1 / (2 * facets));
d = (pos_relative - tool_offset) * (1 / cos(6.28318530717959 * f) - 1);
pos_out = pos_in + d;
fb_out = fb_in - d;
}
--
atp
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