Composite Finite-time Convergent Guidance Law for Maneuvering Targets with Second-order Autopilot Lag

This paper aims to develop a new finite-time convergent guidance law for intercepting maneuvering targets accounting for second-order autopilot lag. The guidance law is applied to guarantee that the line of sight (LOS) angular rate converges to zero in finite time and results in a direct interception. The effect of autopilot dynamics can be compensated based on the finite-time backstepping control method. The time derivative of the virtual input is avoided, taking advantage of integral-type Lyapunov functions. A finite-time disturbance observer (FTDOB) is used to estimate the lumped uncertainties and high-order derivatives to improve the robustness and accuracy of the guidance system. Finite-time stability for the closed-loop guidance system is analyzed using the Lyapunov function. Simulation results and comparisons are presented to illustrate the effectiveness of the guidance strategy.