PSO–Fuzzy–PID Control with Static Psychrometric Decoupling for Modular Plant Factory Environment

Temperature and humidity control in modular edible fungi plant factories is challenging because of strong bidirectional coupling and mismatched loop dynamics: the pure delay is 1779 s in the temperature channel and 1462 s in the humidity channel. To address this, we developed a control framework that combines a particle swarm optimization (PSO)-based fuzzy proportional-integral-derivative (Fuzzy–PID) feedback controller with static psychrometric decoupling. The static compensation cancels steady-state cross-channel coupling, while the Fuzzy–PID feedback loop handles transient interactions. The system model integrates mechanistic energy/mass balance analysis with random forest regression (coefficient of determination R2 = 0.934 for temperature and 0.927 for humidity), and step-response experiments yield first-order-plus-dead-time (FOPDT) transfer functions. A fourth-order polynomial fit to the Magnus–Tetens psychrometric relation provides the static decoupling. Using an integral of time-weighted absolute error (ITAE) criterion, PSO tunes the initial PID gains (proportional Kp, integral Ki, derivative Kd) for both loops in a six-dimensional search. Physical validation in a 21 m2 oyster mushroom chamber over 23 h achieves ±0.3 °C and ±2.3% relative humidity (RH) maximum deviation from setpoint. In a 1 h comparative test, the PSO–Fuzzy–PID reduced the temperature rise time from 34 min to 17 min and the humidity rise time from 40 min to 20 min, corresponding to a 50.0% reduction in both cases relative to conventional PID. Real-time telemetry completeness reached 99.2% at 1 min intervals, while the 23 h stability record at 1 h intervals achieved 95.8% completeness. This field demonstration validates the strategy in a single chamber during oyster mushroom fruiting; other species or growth stages require re-validation. The edge-first programmable logic controller (PLC) architecture, combined with cloud telemetry and static decoupling, offers a practical, scalable solution for intelligent environmental control in modular plant factories with artificial lighting (PFALs), bridging the simulation-to-reality (Sim-to-Real) gap identified in recent reviews.