#!/usr/bin/octave -q
# Something resembling the air compressor control loop
# Set point in mBar
sp = horzcat(zeros(1,500), ones(1,500)*300, ones(1,500)*500, zeros(1,500), ones(1,500)*200, ones(1,500)*700, zeros(1,500));
N = size(sp)(2);
# compressor motor threshold to start delivering compressed air
global CCVTHRES = 4;
global CCMINP = 200;
global CCK = 0.1;
global CC_DELAYLINE = 10;
global ccout = zeros(CC_DELAYLINE);
global out = 0;
global ccout_i = 1;
function result = motor(v)
global CCVTHRES;
global CCMINP;
global CCK;
global CC_DELAYLINE;
global ccout;
global ccout_i;
global out;
target = 0;
if (v > CCVTHRES)
target = CCMINP + v*(1000/12);
endif
out = (target-out)*CCK;
ccout(ccout_i) = out;
ccout_i = mod((ccout_i + 1), CC_DELAYLINE-1) + 1;
result = ccout(ccout_i);
endfunction
# Integer scale
CC_SCALE=fixed(16,0,256);
# PID coefficients
CC_P=fixed(16, 0, 8);
CC_I=fixed(16, 0, 3);
CC_D=fixed(16, 0, 1);
# last error for derivative calculation
x1 = fixed(16, 0, 0);
# Integral
cc_i = fixed(16, 0, 0);
# Output value in Volt
val = fixed(16, 0, 0);
for t=(1:N)
m = motor(float(val));
err = fixed(30, 0, sp(t)-m);
cc_i += err;
cc_d = fixed(16, 0, err-x1);
val = err*CC_P + cc_d*CC_D + cc_i*CC_I;
val = fixed(16, 0, val / CC_SCALE);
x1 = err;
Y(t) = val;
E(t) = err;
M(t) = m;
endfor
# Plot results
hold on
plot(float(Y), "b;controller output;")
plot(float(E), "r;error;")
plot(float(M), "g;modelled plant output / motor RPS;")
pause