The development and application of theory and methods for solving optimal control problems, the development of tailored numerical optimization methods, as well as the closed-loop implementation of optimal controllers on real-time computer systems. Particular methods include, but are not limited to, the calculus of variations, Pontryagin's maximum principle, dynamic programming, model predictive control and differential games. Control methodologies can be based on first-principles models, data-based models or a combination of both.