Design of robust direct adaptive controllers for SISO systems: time and frequency domain design conditions

This paper presents the design of a robust direct model reference adaptive control (DMRAC) algorithm with focus on the satisfaction of an almost stric tly positive real (ASPR) condition in the presence of plant uncertainty rep resented as either variations in plant parameters or unmodelled dynamics in the form of additive or multiplicative norm bounded perturbations in the t ransfer function. Both the time and frequency domain design conditions for a feedforward compensator have been developed utilizing the robust stabilit y analysis and optimization methods. Illustrative examples are presented to validate the algorithm's use and applicability to control systems with par ametric uncertainty or unmodelled dynamics.