Finite-time convergence of guidance system via fast terminal sliding mode control

In this paper, a new nonlinear guidance law is proposed using a novel form of terminal sliding mode called “fast terminal sliding mode”. The system's states are also divided into two parts with respect to their required stabilization properties and only one part is forced to converge to zero. The faster the line-of-sight angular rate converges to zero, the more stability margin is obtained. Therefore, the resulting guidance law is able to nullify the line-of-sight angular rate in finite time. The finite time convergence property and robustness of the proposed law is also proved using extended Lyapunov stability theorem. Moreover, the control loop dynamics are considered as a first order differential equation due to their significant contribution to stability of the guidance system. Simulation results verify the better performance of the proposed law compared with conventional terminal sliding mode guidance law.