Disturbance Observer-Based Sliding Mode Control for Ventilation Blower-Based Systems: Controller Design and Simulation

This paper presents a disturbance observer-based sliding mode control (DO-SMC) for a ventilation blower-based system (VBS) to enhance control performance. Due to the complexity of physical modeling and the lack of blower specifications, the VBS model is approximated as a second-order transfer function using a black-box system identification approach. Additionally, the VBS model was evaluated using the Nash-Sutcliffe model efficiency coefficient, achieving a fit of 92.77%. To validate the performance of DO-SMC, various simulation scenarios were conducted both in the absence and presence of disturbances. In the disturbance-free scenario, the VBS controller effectively tracked the desired air volume during the inspiratory cycle. However, this effect is less evident at the start of the cycle due to rotor inertia and electrical driver characteristics. Specifically, the simulation data showed a maximum deviation of approximately 47 ml under these conditions. In contrast, under ramp and square disturbances combined with random noise, the proposed controller significantly reduced the steady-state error and improved response time, even in the presence of system uncertainties. Additionally, slight chattering was observed in the control signal, attributed to the controller’s attempts to compensate for abrupt system behavior changes. As a result, accurate estimation of the ramp and square disturbances contributed to enhanced overall control performance by mitigating their effects, even though some residual errors remained in the higher-order tracking dynamics due to system limitations.