Two scale high gain adaptive control

Simple adaptive controllers based on high gain output feedback suffer a lack of robustness with respect to bounded disturbances. Existing modifications achieve boundedness of all solutions but introduce solutions that, even in the absence of disturbances, do not achieve regulation. In this paper a new modification that achieves the desired robustness without the side-effect of undesirable solutions is proposed. The modification features two data-driven stability indicators. Intuitively, the first indicator drives the ‘closed-loop poles’ to the closed right half plane while the latter provides fine-tuning that prevents persistent imaginary axis poles and their associated undesired behaviour.