A Robust Universal Controller

The present paper advocates the use of ODE-based (instead of algebra-based) constraints on the output variables of a controlled system, and the use of dynamic control laws (instead of static control laws)—when finite but small errors in honoring the constraints are considered acceptable. It is assumed that the sensor signals are reliable and have good signal-to-noise ratios, that the controller has ample computational power, and that the hardware/software “sampling time” ts is much smaller than the system characteristic time tg. A universal dynamic control law is proposed which does not require detailed knowledge of the system itself—and is therefore completely robust with respect to uncertainties of the system—provided the control problem to be solved is reasonable. The meaning of the equivocal word “reasonable” will be explained.