Fuzzy oxygen control system for the indirect calorimeter of premature infants

The indirect calorimetric system of measuring O-2 consumption and CO2 produ ction has been developed for energy expenditure estimation of premature inf ants. This apparatus requires an input room air mixing with pure oxygen to obtain a stable gas with definite oxygen concentration flowing into the hoo d for neonatal breath or supplemental oxygen treatments. In this paper, we propose an oxygen control system based on fuzzy control logic to automatica lly adjust the mixing ratio of room air to pure oxygen gas from the hospita l's supply system, designed for premature infants. It is designed to reduce the risks of oxygenic toxicity and retinopathy of prematurity by lowering the overshoot of oxygen concentration. Its performance was evaluated and op timal membership functions were obtained. As a result, the system is quite robust with little effect caused by disturbance and has little or no oversh oot when step changing the level of oxygen concentration in the mixed gas.