Disturbance observer-based higher order sliding mode control with switching gain adaptation

This paper proposes a disturbance observer (DOB)-based adaptive non-homogeneous higher order sliding mode control (HOSMC) scheme. Given a large initial tracking error, the proposed HOSMC provides fast convergence rate by using non-homogeneous finite time stabilization. In addition, a disturbance observer based adaptive control method is employed to identify bounded uncertainties. To solve the overestimation problem, DOB is introduced to compensate for the low-passed uncertainties, and an adaptive first order sliding mode control term by using the equivalent control technique is employed to handle the fast-changing components of the uncertainties beyond the pass-band of DOB. Simulations show the effectiveness of the proposed algorithm.