procedure TForm1.followtrack;    /////////////////////////////////Spurverfolgung
var
  m: integer;
  sensor1, sensor2, sensor, regel, yp, yi, yd: real;

begin
  sensor1:=0;
  sensor2:=0;
  for m:=1 to sensoranzahl do begin
    if chk(m) and (sensor1=0) then begin
      if m<=sensoranzahl/2 then  sensor1:=-sensoranzahl/2-1+m
        else sensor1:=m-sensoranzahl/2;
      if m<>sensoranzahl then begin
        if chk(m+1) then begin
          if m+1<=sensoranzahl/2 then  sensor2:=-sensoranzahl/2+m
            else sensor2:=m+1-sensoranzahl/2;
        end;
      end;
    end;
  end;

  if sensor2<>0 then sensor:=(sensor1+sensor2)/2 else sensor:=sensor1;

  yp:=(kp/100)*(sensor/(sensoranzahl/2));
  yi:=yialt+(tast/100)/(ki/100)*sensor;
  yd:=(kd/100)*(sensor-sensoralt)/(tast/100);

  yialt:=yi;
  sensoralt:=sensor;

  regel:=yp+yi+yd;

  button6.caption:=floattostr(regel);

  if regel<0 then begin
    vr:=vr+abs(regel);
    if vr>=vmax then begin
      vr:=vmax;
      vl:=vl-abs(regel);
      if vl<0 then vl:=0;
    end;
  end;
  if regel>0 then begin
     vl:=vl+abs(regel);
     if vl>=vmax then begin
      vl:=vmax;
      vr:=vr-abs(regel);
      if vr<0 then vr:=0;
     end;
  end;     

end;