Fast Convergent Nonsingular Terminal Sliding Mode Guidance Law with Impact Angle Constraint

In this paper, a nonsingular, essentially continuous and finite time fast convergent guidance law with impact angle constraint for some missiles attacking the targets with zero miss-distance and terminal impact angle constraint is presented by using terminal sliding mode control and finite time control theories. First, in order to avoid the singularity of terminal sliding mode control, and make the state variables achieve the equilibrium point in finite time, a fast convergent nonsingular terminal sliding mode control algorithm is improved. In the algorithm, the fast convergent nonsingular sliding mode function is employed to construct the sliding surface, and an adaptive exponential reaching law is employed to the reaching, so the system trajectory converges quickly from any initial state to the equilibrium point in the entire reaching phase. Then, a fast convergent nonsingular terminal sliding mode guidance law with impact angle constraint is presented base on this algorithm. Finite time control theory is used to analyze the convergence of the guidance law. Due to its inherent nonsingularity attribute, continuity and faster convergent rate, higher tracking precision of the desired impact angle in a shorter time interval with smoother guidance command can be guaranteed compared with conventional terminal sliding mode guidance law. A number of numerical simulation examples are implemented to justify the effectiveness of the proposed guidance law.