A comparative study of conventional nonsmooth time-invariant and smooth time-varying robust compensators

Variable structure-based robust compensators are general approaches to deal with uncertain nonlinear dynamic systems. The bang-bang (discontinuous-type) compensator and the saturation (continuous-type) compensator are the two common robust compensators used in variable structure controllers. This paper presents a comparative study of these two nonsmooth time-invariant robust compensators with a smooth time-varying compensator and reveals the superiority of the smooth time-varying compensator over the nonsmooth robust compensators.