Terminal sliding mode based impact angle guidance law with observability enhancement

In this paper, a new impact angle constraint guidance law for stationary targets is presented based on terminal sliding mode control (TSMC) theory. The finite time stability of the line-of-sight (LOS) angular rate have finite time convergence under the proposed guidance law is obtained in theory. The boundness of unknown parameter estimation error is proven through Lyapunov method. Also, higher target observability is guaranteed by forcing an oscillatory missile motion trajectory. Numerical simulations results are provided to demonstrate the effectiveness of the proposed guidance law under different initial conditions.