A Switching Control Framework to Enforce Performance Attributes for Uncertain Nonlinear Systems under Control Input Magnitude and Rate Constraints

When a system is operated with controllers designed via the prescribed performance control (PPC) methodology, internal instability may appear as an effect of control input magnitude and rate saturation. In this paper we propose a switching control framework to effectively alleviate this phenomenon. Two control units are utilized; a PPC and a Safety Controller (SC). Initially, control action is given to PPC, which switches to SC only when PPC becomes saturated and the risk of instability is high. The SC unit is designed to maintain system operation whenever PPC fails; thus avoiding the appearance of controller instability. Control is given back to PPC unit when the probability of internal instability is low. The proposed control solution is of low-complexity and achieves performance attributes on the output tracking error while preserving the boundedness of all signals in the closed-loop. Simulations clarify and verify the theoretical findings.