Advancements in knowledge and technology have led to an evolution of greenhouse operations: from simple transparent shelters to (one of) the most profitable sectors in agricultural industry. The understanding of the physiological and biological processes of the inside micro-climate and crop, as well as the introduction of climate control, were critical for improving both the quality and production rate. Advanced control strategies like MPC involve the application of horticultural and plant physiological knowledge using mathematical models that describe the dynamical behavior of the greenhouse and crop. An on-line control method balances the benefits of crop yield and costs of the climate control equipment. The increasing production and cultivation rate in response to the growing demand is at a point where the focus and tension is shifted to the energy input and environmental footprint of greenhouse operations. This stimulates the agricultural industry to provide sustainable solutions. An innovative greenhouse is developed by BBBLS Solutions, that uses a soap bubble cavity which improves the thermal properties and energy efficiency. The concept is in development phase and is acknowledged that there is potential for improved climate control and automation of the control of the soap bubble cavity. This research introduces a MPC strategy for controlling the greenhouse climate and the soap bubble cavity. The greenhouse processes are described by a mechanistic model, which simulates the inside climate variables as a function of the greenhouse structure, outside environmental conditions and climate control equipment. The dynamics of the soap bubble cavity and the corresponding thermal varying properties were then augmented in the climate model. The augmented model is used as a predictor for the future dynamics of the greenhouse climate, for which the optimizer generates a control input sequence for the climate control equipment and soap bubble generators inside the cavity. The MPC implementation results demonstrate that the greenhouse temperature can be controlled within the pre-defined bounds and that the filling of the soap bubble cavity is with respect to outside conditions and priorities. Furthermore, the MPC strategy supports real-time control as the CPU time can be less than the time between control instances. The proposed methodology is an initial attempt but proves to be a promising concept for further development.

With the rapidly growing world population and improving living standards of upcoming economies, the demand for fresh food is increasing vastly. Greenhouses have proven to be very effective in increasing crop yield since they offer a sheltered environment that can be controlled. Greenhouse growers need to take care of many processes, among which are maximising the crop yield while using as little resources as possible and controlling the indoor climate. An approach to alleviating demand for experienced growers is to automate processes within the greenhouse that aid in setpoint generation and setpoint tracking. Existing literature has presented multi-level architectures to cope with the two different timescales on which the two greenhouse subsystems act, i.e., the crop and greenhouse indoor climate subsystem. Current approaches in literature employ model-based techniques, which need tedious calibration per considered situation due to the influences of the local weather, environment and highly non-linear underlying physical processes. Therefore, these model-based approaches are scarcely used in the horticultural sector. Thus, this thesis proposes a data-driven control scheme that deals with long-term crop production control while taking into account resource usage. The proposed control scheme uses temporal and functional decomposition of the overall problem to accommodate the different timescales on which the greenhouse indoor climate subsystem and crop subsystem act. With the focus on the entire growing season, this thesis emphasises the importance of the climate strategy for crop production control. The aim of this thesis is threefold. Firstly, a non-linear simulator model for the crop dynamics has been selected, adapted, and calibrated, using the Autonomous greenhouse challenge (AGC) dataset. Secondly, the overall crop production control problem has been decomposed into a hierarchical structure, including two subproblems with different objectives, acting on different timescales and using different system representations. The communication protocol between the two layers has been determined, and the setpoint tracking controller is established for the lower layer and tested on a benchmark temperature reference trajectory. Thirdly, the Data-enabled predictive control (DeePC) algorithm is leveraged for the crop production control problem and compared in simulation against a conventional Economic model predictive control (EMPC) setpoint generating controller. Both use the aforementioned established setpoint tracking controller for controlling the greenhouse towards the generated climate strategies. In simulation, it is shown that the DeePC setpoint generating controller results in a climate strategy that results in a lower crop yield by 1.51% when compared to the EMPC climate strategy and 0.54% less when compared to the predefined benchmark reference trajectory. Furthermore, the resource usage needed for the climate strategy proposed by the DeePC setpoint generating controller uses 1.75% more heating resources when compared to the EMPC setpoint generating controller and 11.1% more when compared to a predefined temperature setpoint trajectory. The DeePC climate strategy results in 7.92% and 5.27% less electricity use when compared to the EMPC and predefined benchmark climate strategy, respectively. The DeePC climate strategy CO2 usage is 11.4% less when compared to the EMPC climate strategy CO2 usage and 20.8% less when compared to the predefined benchmark climate strategy. The decrease in resource usage compensates for the lower crop yield of the DeePC climate strategy. According to the metric of net economic profit, the DeePC generated climate strategy outperforms the benchmark climate strategy and EMPC climate strategy.

The world population is growing rapidly and the demand for healthy food grows with it. Greenhouse cultivation provides an efficient way to grow crops in a protected and controlled environment. In the past, many greenhouse control algorithms have been developed. How- ever, the majority of these algorithms rely on an explicit parametric model description of the greenhouse. These models are often based on physical laws such as conservation of mass and energy and contain many parameters which should be identified. Due to the complex and highly non-linear dynamics of greenhouses, these models might not be applicable to control greenhouses other than the one for which the model has been designed and identified. Hence, in current horticultural practice these control algorithms are scarcely used. Therefore, the need rises for a control algorithm which does not rely on a parametric system representa- tion but rather on input/output data of the greenhouse system, hereby establishing a way to control the system with unknown or unmodeled dynamics. A recently proposed algo- rithm, Data-Enabled Predictive Control (DeePC), is able to replace system identification, state estimation and future trajectory prediction by one single optimization framework. The algorithm exploits a non-parametric model constructed solely from input/output data of the system. This algorithm is employed in order to control the greenhouse climate. It is shown that in numerical simulation the DeePC algorithm is able to control the greenhouse climate. A comparison is made with the conventional Nonlinear Model Predictive Control (NMPC) algorithm in order to show the differences between a predictive control algorithm that has direct access to the non-linear greenhouse simulation model and a purely data-driven predic- tive control algorithm. Both algorithms are compared based on reference tracking accuracy and computational time. Furthermore, it is shown in numerical simulation that the DeePC algorithm is able to cope with changing dynamics within the greenhouse system throughout the crop cycle.