A scaled-down model of a dairy barn to imitate a livestock building for modelling and control of environmental conditions.

ABSTRACT

Heat stress has vital importance in livestock farming due to the physiological changes on the animals so that meat and milk production is significantly degraded. Recently, the hereditary and mental effects of environmental conditions have also been discussed for future generations. Therefore, high-level automation solutions are required to keep the environmental conditions in the barns as optimal as possible. In this paper, a hangar-type scaled-down barn was experimentally designed for modelling and control of the environmental conditions. First, the temperature-humidity index (THI) which is a measure of the heat stress, was stabilized to its critical value in two regions of the barn by using proportional-integrative-derivative (PID) controller. The ventilation fans were controlled at variable speeds so that energy efficiency was also provided when compared to the on-off control. Second, we proposed the state-space modelling of the coupled temperature and humidity dynamics for the interior space of the barn so that the obtained model can be utilized for mathematical analysis and accurate control. Specifically, state monitoring and prediction, optimal control, and observer-based sensor-less control are to be applied based on its state-space model. The parameters of the state-space model were here estimated with an Extended-Kalman Filter (EKF). Performances are calculated in terms of mean square error (MSE), and the performance values were found to be less than 5% for stabilization and less than 2% for modelling, respectively. The proposed scaled-down barn model is a low-cost design that can be used as an example for those who work in this field to conduct experimental studies before making large investments. Barn design can also be modified for modelling, analysis, and control of new heat stress measures in the future.