ABSTRACT This paper investigates the robust semi‐global output regulation of uncertain linear systems with input saturation. In this setup, one cannot apply off‐the‐shelf techniques to reject structural uncertainties due to numerical issues caused by the two time scales but also due to technical issues generated by the input saturation. To solve this problem, we combine internal model principle with low gain technique and singular perturbation theory. Explicitly, the regulator design is based on the computation of…