Adaptive asymptotic tracking of parametric strict-feedback systems in the presence of additive disturbance

This paper deals with the tracking control of uncertain, nonlinear, parametric strict-feedback systems subjected to additive disturbances. A continuous adaptive control law is proposed using a modified backstepping design that ensures the tracking error is asymptotically driven to zero. Despite the disturbance, the adaptation law does not need the standard robustifying term (σ-modification or e₁-modification) to ensure the aforementioned stability result. A numerical example illustrates the main result.