High-Gain Functional Observer Based Output-Feedback Sliding-Mode Control with Chattering Avoidance^*

A novel observer-based output-feedback sliding-mode control method is introduced for multivariable linear plants. The central element is a high-gain functional observer (HGFO) that mitigates the impact of parametric uncertainties and exogenous disturbances and has an inherent chattering avoidance feature to cope with parasitic elements (unmodeled dynamics). A variable-gain unit vector control is provided to guarantee global exponential stability for the closed-loop system. Notably, the new HGFO transfer function based approach offers analysis and design simplicity by circumventing the more involved matrix-based classical high-gain observer (HGO) multivariable framework. Through numerical simulations considering an application example with a DC motor with resonant unmodeled dynamics, the efficacy of the proposed control strategy in achieving remarkable control accuracy and chattering avoidance is illustrated.