% PIPE FLOW SETUP
% RELAY ONTROLLERS
  clear all
  ROLD=0.0;HOLD=0.0;SENSOR=ROLD;
  TARGET=5.0;LOAD=0.0;DUMP=10.0;      
  X=0.5;Y=1.0;A=0.1;B=1.0;Z=1.0;
  NIT=10000;MIT=500;TIME=0.0;
  BIAS=5.0;JUMP=5.0;BAND=0.0;
  DELT=0.0005;     
  for IT=1:NIT
  TIME=TIME+DELT;     
  if(IT>MIT) ... 
   SENSOR=R(IT-MIT); end; 
  ERROR=TARGET-SENSOR;
  CONTROL=BIAS;
  if(ERROR>+BAND) ...
    CONTROL=BIAS+JUMP;end; 
  if(ERROR<-BAND) ...
    CONTROL=BIAS-JUMP;end;     
  ABC=Z*CONTROL-B*HOLD;
  XYZ=HOLD+LOAD-Y*ROLD;
  HNEW=HOLD+DELT*ABC/A;
  RNEW=ROLD+DELT*XYZ/X;
  T(IT)=TIME;R(IT)=RNEW;
  ROLD=RNEW;HOLD=HNEW;
  end; plot(T,R)
  xlabel('time')
  ylabel('volts')
  title('pipe relay control')