Upper left panel shows the general layout of the driving unit-pneumatic ventricle system. Ts and Td represent the systole and diastole time respectively. Upper right panel illustrates the pneumatic ventricle. Dashed and countinuous lines inside the ventricle represent two different position of the membrane. Vair and Pair (Vvad and Pvad) are the volume and pressure into the part of the ventricle connected to the air tube (into the ventricle). Lower panel shows the pressure-volume relationship which has been assumed for the pneumatic ventricular diaphragm in its end-systolic and end-diastolic position. Ced and Ces are the diaphragm compliance at end-diastolic and end-systolic position respectively. Vmin and Vmax are the minimum and the maximum pneumatic ventricular volume respectively.