FxTDO ‐based non‐singular terminal sliding mode control for second‐order uncertain systems

In this study, a composite robust control approach with non‐singular terminal sliding mode control and fixed‐time disturbance observer (FxTDO) is proposed for a class of second‐order non‐linear systems in the presence of matched uncertain disturbances. A bi‐limit‐weighted homogeneous FxTDO is designed based on the efficient utilisation of power functions obtained by the differentiation error amplification strategy. The FxTDO enjoys a fast convergence rate and simple parameters tuning process. By introducing the disturbance estimation to directly compensate the total disturbance in the composite control law, only a particular small gain‐based discontinuous control term is needed to guarantee the existence of sliding mode, and chattering phenomenon can be attenuated. The simulation results revealed the effectiveness of the proposed method.