uncertainty cancellation based second-order sliding mode for finite-time thrust vector control

This paper proposes a new uncertainty cancellation based second-order sliding mode control law to control uncertain nonlinear systems in a finite time. the presented algorithm consists of a term that not only estimates the uncertainty based on sliding mode observer theory but also provides second-order sliding mode behaviour. therefore, the recommended algorithm is robust in the presence of uncertainties. additionally, it offers a smooth control signal, ensuring that chattering does not appear. in this method, the finite-time convergence of the closed-loop system error is guaranteed by using mathematical relations. for this aim, a lyapunov candidate function is first defined based on the sliding variable and the estimation error. then, by establishing the finite time stability condition, the stability of sliding variable and estimation error is ensured. additionally, the convergence time is explicitly determined. this particular design is applied to a thrust vector-based flying object to track the pitch angle. the efficiency of the thrust vector system will be demonstrated through computer simulations and compared with two other observer-based sliding mode methods.