Robust H-Infinity Control of a Cold Storage System for Preservation of Leafy Vegetables in Nigeria

Food preservation is the process of handling and preparing food to prevent or significantly reduce spoiling (loss of nutritional content, edibility, or quality) that is brought on or hastened by microorganisms. Utilizing a straightforward yet efficient refrigeration system as a farm storage facility enhances the value of goods and lengthens their shelf life. Ugu (fluted pumpkin), efo tete (amaranth), and spinach are examples of green vegetables mostly consumed in Nigeria that should be kept between 0°C and 5°C to extend their shelf life and avoid wilting. Bacterial growth and respiration are significantly reduced in this temperature range. By slowing down product metabolism and the activity of microorganisms that cause quality degradation, temperature control contributes to an extension of postharvest life. As a result, ripening is slowed down, reserves are kept at a lower respiration rate, and there is less vapor pressure between the product and the environment, which minimizes water loss. By slowing down the rate at which quality declines and preserving the product's nutritional content, these elements help to keep freshness. This has a great potential to serve as a springboard for Nigeria to reach its national food security objective more quickly. The H-infinity control strategy is utilized to generate outstanding performance and robustness in the face of uncertainties and disturbances in order to accomplish this goal. The loop shaping design (LSDP) method is used in this study to design the H-infinity controller. The H-infinity controller was able to reach an air temperature and a goods temperature within the specified temperature range of 0 °C and 5 °C, which ensures the preservation of leafy vegetables, according to simulation findings during a 24-hour period using MATLAB/SIMULINK 2026a.