What is control?
Control theory is the mathematical study of systems that respond to uncertain and dynamic environments. Control engineering is the practice of designing such systems, control systems, in applications like aerospace, electronics, and industrial-scale chemical synthesis.
In biology, medicine, ecology, and elsewhere, control systems science is a set of emerging techniques for designing experiments and making inferences about natural or extant control systems.
Control systems science is especially helpful when we encounter complex systems that are difficult to understand with classical experimental design and statistical inference paradigms.
Developing control systems science is a step towards achieving better engineering outcomes in biology and medicine.
Control systems in biology and medicine include extant homeostatic, immune, nervous, and developmental processes, as well as clinical decision-making processes, treatment protocols, and devices like pacemakers and ventilators. The control framework therefore spans theoretical, basic science, translational, applied, and clinical approaches. A theoretical foundation can guide the design of descriptive mathematical models, which can guide the design of experiments and the design of clinical trials, which can guide the design of devices and therapies.
This kind of reasoning can also run in the other direction: the fact that a treatment works can be an indispensable piece of evidence about the underlying biological control system.
My enduring theoretical interest is in the question, what kinds of systems can exist? This is a question that is also studied in fields like thermodynamics and theoretical computer science; I like the particular techniques in control theory because I've lived with them longest, and because I have found them useful and beautiful.