A Robust Universal Controller

Abstract

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 small but finite errors in honoring the constraints are considered acceptable. It is assumed 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'' t_s is much smaller than the characteristic time t_g of the system. A 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 posed is reasonable. The meaning of the equivocal word "reasonable" will be explained.