Optimal guidance law design for reentry vehicle using virtual displacement concept

The new predictive guidance law for reentry vehicle is presented in this paper. The proposed approach is based on the fact that lateral forces are formed to a plane perpendicular to the reentry vehicle velocity. In particular, the nominal ground location is defined as the ground location generated by the zero lift trajectory, the virtual displacement is defined as the small changes of the nominal ground location, this changes is caused by any instantaneous lateral force at the beginning of the trajectory. The optimal direction of the lateral force is searched by the solution to the optimal virtual displacement, in which case the virtual displacement is pointing to the target ground location. The analytical solution to the reentry trajectory and the linear quadratic gauss (LQG) method are used in this guidance method. The simulation results show that the effectiveness of proposed method.