Robust control of fermentation temperature–humidity under process disturbance and uncertainty

Abstract Temperature and humidity regulation is crucial across industrial and real‐life applications, where precise environmental control impacts efficiency, product quality, and system reliability. However, the coupled nature of temperature and humidity dynamics, combined with system inertia and time delays, presents significant challenges for conventional control strategies. While traditional approaches such as proportional–integral–derivative (PID) and fuzzy PID have been widely explored, they often rely on accurate system models and involve complex tuning procedures. To address these limitations, this study proposes a hybrid active disturbance rejection control (ADRC) scheme for robust decoupling temperature–humidity regulation in a fermentation chamber. The approach applies first‐order ADRC to the temperature channel and second‐order ADRC to the humidity channel, considering their distinct dynamic behaviours and delay characteristics. The cross‐coupling effects are modelled as lumped disturbances and compensated in real time through an extended state observer (ESO), enabling model‐independent decoupling and enhanced disturbance rejection. Simulation results demonstrate that the proposed controller achieves comparable response speed to the conventional PID‐based decoupling method, while significantly improving robustness, disturbance rejection, and steady‐state accuracy under parameter variations. The method maintains a simple structure suitable for practical industrial implementation.