关键词: nonlinear system, adaptive control, Backstepping, unknown control direction

Abstract: The adaptive stabilization problem of nonlinear systems are studied. For a class of uncertain nonlinear systems with unknown control direction, we proposed a robust adaptive backstepping scheme withσ-modification by introducing Nussbaum function and Backstep- ping methods, and proved that all the signals of the closed-loop systems are bounded.

Key words: nonlinear system, adaptive control, Backstepping, unknown control direction