Mechatronic system for controlling the humidity of the greenhouse microclimate

Abstract

The influence of general parameters of temperature and humidity on the microclimate of small greenhouses is analysed. The main properties that provide the most favorable conditions for plant growth and development are identified, among which air humidity plays a significant role. To ensure a stable humidity regime inside the greenhouse, it is necessary to maintain a humidity balance. The aim of this work is to create a mechatronic system for controlling air humidity in a greenhouse. The peculiarity of the approach is a shifted algorithm for controlling sprayers based on a daily weather forecast. A computer model of the greenhouse complex was substantiated and developed, which takes into account additional compensation for water vapor, convection, and forced air movement in the greenhouse. Based on the results of the research, a mathematical model of changes in water vapor flow in the greenhouse in accordance with changes in ambient air humidity during the day was developed in the SOLIDWORKS software environment. A simulation of changes in air parameters in a greenhouse during one day was carried out to forecast the weather in the Kherson region (May 17, 2023). The modeling was based on the design parameters of the greenhouse, the initial temperature in the greenhouse of 20°C, the ambient temperature in the range from 13.9°C to 26.2°C according to the weather forecast, and the initial air humidity of 70%. It was found that the obtained characteristics allow us to estimate the overall coefficient of air saturation with water vapor, which served as the basis for determining the required performance of compensating injectors and developing a control cyclogram for the greenhouse air humidity stabilization system. To ensure stable humidity in the greenhouse, a mechatronic hydraulic fogging system was developed. Based on the results of the model experiment, the coordinates of the injectors were determined and their operation mode, namely the control algorithm, was developed. The results of the study and the developed control algorithm are suitable for use in mechatronic microclimate control systems, taking into account daily changes in environmental parameters. The algorithm provides for switching on the fogging system, updating the current values of variables, polling sensors, and updating the set of control commands. The logic of the control process is based on the definition and development of modes in three humidity ranges: 70-65%; 65-60%; 60-50%