Dual-layer adaptive sliding mode control

This paper proposes new and novel equivalent control-based adaptive schemes for both conventional and super-twisting sliding mode control algorithms. The approach is based on a dual layer nested adaptive scheme which is quite different to the existing schemes proposed in the sliding mode literature. The new adaptive schemes do not require knowledge of the minimum and maximum allowable values of the adaptive gains, and more importantly do not require information about the upper-bound of the disturbances and their derivatives. The underlying idea can be applied to a variety of sliding mode control structures and relies more on the availability of an online approximation of the equivalent control, than the precise control law used to induce and maintain sliding.