New research by Xu Dan and Hesham A. Ahmed shows that, although optimal control has been used extensively for greenhouse climate management, its application to plant factories is still in its infancy.
In this paper, the profitability of growing lettuce in a Chinese plant factory (vertical farm) is investigated by means of optimal control computations. To that end, first, a lettuce growth model is adapted to fit a plant factory environment.
Next, this model is calibrated and validated using nine sets of experimental data with different LED light intensities. Using the calibrated and validated model, optimal control computations are used to produce a 3D plot revealing the influence of the electricity and lettuce price on maximum profit.
Lettuce's physiological demand for dark periods during artificial lighting is incorporated by fixing this dark period to eight hours a day. Therefore, the optimal LED light intensity pattern obtained from the optimal control computations could be used in the actual production process.
Click here to access the research.