Improved nonsingular fast terminal sliding mode controller for nonlinear systems

In this paper, a novel control method is proposed for single-input single-output second-order nonlinear systems. The proposed controller guarantees the system reach to the sliding mode surface from any initial states and converge to origin along the surface in finite time while solving the problem of singularity. Compared with traditional fast terminal sliding mode (FTSM) controller, the proposed controller needs less convergence time resulting from a novel sliding mode surface design. A method used in nonsingular terminal sliding mode control is applied in this paper to eliminate the singularity problem. Furthermore, based on the novel sliding mode surface design, a parameter adaptive rule is proposed to make the sliding mode surface close to the initial sates. In this way, the chattering phenomenon is reduced. Finally, simulation results show that the new controller needs less convergence time compared with FTSM, while eliminating the singularity problem and reducing the chattering phenomenon.