Hierarchical control for nonsmooth sandwich systems with dead‐zone

Abstract This paper proposes a hierarchical control architecture for trajectory tracking in sandwich systems with dead‐zone nonlinearities. The architecture comprises three layers: (1) an inner‐layer integral sliding mode controller (ISMC) and a nonsmooth observer (NSO) to address sensitivity to control inputs and unobservable internal states; (2) a middle‐layer dead‐zone inverse model (DZIM) controller to mitigate the adverse effects of dead‐zone nonlinearities; and (3) an outer‐layer model predictive controller (MPC) combined with an extended state observer (ESO) to handle trajectory tracking and disturbance rejection in generalized linear systems. The stability of the closed‐loop system is rigorously analyzed using Lyapunov theory. Simulation results demonstrate the effectiveness and applicability of the proposed method in an electrohydraulic servo press system, achieving a 25 % improvement in tracking accuracy and a 30 % reduction in disturbance effects compared to traditional sliding mode control. The proposed method not only addresses practical challenges in electrohydraulic systems but also offers a robust framework for controlling other nonlinear systems in mechanical engineering.