SDRE missile guidance law

In this work, a state dependent Riccati equation (SDRE) missile guidance is formulated and studied. With the aid of a line of sight (LOS) fixed coordinate, the order of the system equations describing the three dimensional missile guidance problem is reduced to three. In addtion, the computational effort of solving SDRE is less than the usual guidance formulations which often have the order greater than three. Three different state dependent coefficient forms are proposed and compared under the consideration of optimality and implementation. For more constructive design, a simple shift of variable is also introduced to achieve better performance. From the results of numerical experiments, we also find that the proposed SRRE guidance law outperforms the conventional PPN guidance (for navigation constant equals 5) in the sense of time but at the cost of energy.