Disturbance observer-based fixed-time control for nonlinear systems with multiple disturbances

Abstract

The fixed-time control is researched for the nonlinear system subject to multiple disturbances, which contain an external disturbance with unknown frequency and an unknown bounded disturbance. An adaptive nonlinear disturbance observer is devised to estimate the unknown frequency disturbance generated by an exogenous system. On this foundation, a composite fixed-time control scheme is proposed by combining the [Formula: see text] control and the fixed-time theory. It guarantees that the expected control performances of system can be achieved under the existence of multiple disturbances. Eventually, the validity of the control scheme is proved via simulation examples.