Design of the guidance law based on the virtual target for ship-to-air missile beyond visual range

The ship-to-air missile could drop into the sea at the beginning of the midcourse guidance,when the target flights in the low altitude beyond visual range.Towards to this phenomenon,the method of the virtual target was presented to perfectly solve the problem.Applying the concept of the pseudo control variable and the theory of the linear quadratic optimal control,an optimal guidance law was designed.The simulation results show that the method of the virtual target has better effect and the designed optimal guidance law is feasible.