Strictly convergent nonsingular terminal sliding mode guidance law with impact angle constraints

In this paper, we develop a strictly convergent nonsingular terminal sliding mode guidance law for missiles with impact angle constraints. A novel nonsingular terminal sliding mode (NNTSM) control scheme is first proposed to improve the effectiveness of conventional terminal sliding mode in the whole phase plane, where the time taken to reach both the sliding surface and equilibrium point is guaranteed to be finite time. The proposed NNTSM control scheme is then applied to the guidance law of missiles with impact angle constraints, where extended state observer is designed to estimate the target acceleration. Simulation results are presented to validate the proposed guidance law.