Robust global terminal sliding mode control of SISO nonlinear uncertain systems

A global terminal sliding mode controller is proposed for higher order SISO nonlinear dynamic systems by employing the fast terminal sliding mode concept in both the reaching phase and the sliding phase. The inherent dynamical properties of the fast terminal sliding modes and the recursive mechanism for application in higher order systems are explored. A control design procedure is developed. It is shown that, by suitably choosing the parameters of the fast terminal sliding modes, the system state variables will reach the fast terminal sliding manifolds within a desired finite time, and stay in the sliding modes thereafter, resulting in the convergence to the equilibrium in a finite time which can also be prespecified. The control law designed, which is called "the global terminal sliding mode control", is nonlinear and continuous. It does not cause chattering in the reaching phase and sliding phase. The robustness analysis shows that the proposed global terminal sliding mode controller has superior robustness in system uncertainties and external disturbances. Simulation studies are presented to validate the proposed scheme.