Design of three-dimensional nonlinear guidance law with bounded acceleration command

This paper concentrates on the problem of designing a three-dimensional nonlinear guidance law accounting for saturation nonlinearity and the dynamics of missile autopilot based on a command filtered backstepping (CFBS) scheme. In the design, the nonlinear kinematics of target-missile engagement is considered in the spherical coordinate system and the dynamics of the autopilot is considered as a second-order term. The CFBS scheme is utilized to blend the command filtering approach into standard backstepping method to avoid the complex computation of the analytic derivatives of the intermediate control signals. A command filter with a saturation limiter embedded and some auxiliary filters are combined together to address acceleration command saturation. Simulation results show that even though subject to saturation constraint, the proposed guidance law achieves excellent guidance performance in terms of missed distance.