Design of Multivariable PID Control Scheme for Humidity and Temperature Control of Neonatal Incubator

Abstract

A preterm baby requires an environment identical to that of the womb. Therefore, a neonatal incubator can be used to provide an environment comparable to that of neonates in women. In this study, the overall system was designed using mathematical analysis. The neonate is shown as a single lump with two layers: core and skin. The model included all components of the neonatal incubator system. The neonatal incubator system was simulated using the MATLAB/Simulink software. Both the skin and air modes have a closed-loop simulation model controlled by a multivariable PID controller. In fact, we performed tuning using the sequential loop-closing tuning method. The simulation results show that for the skin temperature ( $\text{T}_{\mathrm {s}}$ ), the overshoot is reduced from 23.1096% to 6.117% and the settling time is also reduced from 4066.8 seconds to 755.8 seconds using decoupling and sequential loop closing tuning method with PID controller. Similarly, for air temperature ( $\text{T}_{\mathrm {a}}$ ), the overshoot was reduced from 59.65% to 7.2456%, and the settling time was also reduced from 2302.1 seconds to 530.48 seconds. For both skin mode and air mode operation, using decoupling and sequential loop closing tuning method with PID controller, the relative humidity has an improved settling time with an overshoot of 8.559% and 9.43%, respectively. In general, a PID controller improves the overall system performance. The PID controller accelerated the system by reducing the time constant.

Keywords

• Humidity
• multivariable PID controller
• neonatal incubator
• temperature