Filtered Smith predictor with feedback linearization and constraints handling applied to a solar collector field

Recently, the feedback linearization (FL) technique was proposed to control the temperature in a solar field using the water flow rate as the manipulated variable. Nevertheless, the system shows non-desirable control signal oscillations caused by a delay uncertainty. In this paper, the resulting dynamics obtained after applying the FL transformation over the process nonlinear model is approximated by a first-order model plus dead time, and a filtered Smith predictor (FSP) is proposed as control strategy. This controller deals with dead-time errors but also includes control signal saturation caused by flow rate constraints. Simulations demonstrate the robustness of the FSP structure in comparison to a simple PID when a faster closed-loop is required in a system with delay uncertainties.