H-infinity Robust Controller for Precise Temperature Regulation in an Agricultural Growth Chamber Prototype

Abstract

Temperature regulation is crucial for crop yield optimization in controlled environment agriculture, yet achieving such accuracy is challenging due to system nonlinearities and external disturbances. Since H_(∞ )control is an established theory, its experimental validation on low-cost hardware for agricultural systems remains limited. This paper presents robust control for a nonlinear system, targeting an internal temperature of growth chamber agriculture. Moreover, the primary contribution is the demonstration of a systematic and practical methodology for designing, implementing, and validating an H_(∞ ) controller on an Arduino-based growth chamber prototype, bridging the gap between complex control theory and accessible implementation. A simplified linearized thermal model was derived from a lumped parameter approach using energy balance equations. A second-order weighting function was systematically designed using loop-shaping principles to guarantee robust performance against unmodeled dynamics and sensor noise. The resulting controller was synthesized in MATLAB and deployed on an Arduino Mega microcontroller for experimental testing. Simulations predicted high-precision tracking with a Root Mean Square Error (RMSE) of 0.037 °C and an Integral Absolute Error (IAE) of 0.70. Subsequent experimental validation under real-world conditions confirmed the controller's efficacy, achieving stable temperature regulation within ±2 °C of the set point. The experimental validation yielded an RMSE of 1.04 °C and an IAE of 0.924, highlighting a notable but analyzed performance gap between the idealized simulation and the physical implementation. The results of this work were also compared with MPC and PID controllers, showing the proposed approach demonstrated satisfactory performance and confirming the robustness and stability of the control strategy in practical conditions. This work concludes that the H_(∞ ) framework provides a computationally efficient pathway to achieving robust temperature control on accessible hardware, making advanced control techniques more feasible for distributed agricultural applications