TERMINAL GUIDANCE ALGORITHM FOR RAMJET-POWERED MISSILES

The terminal guidance design problem for a long-range bank-to-turn (BT T) ramjet missile involves a completely coupled pitch-yaw-roll nonline ar dynamics model. Because of these nonlinear dynamics, an optimal sol ution for acceleration and roll rate commands can be found only by num erical methods for solving two point boundary value problems. Because the roll-rate dynamics of the state-of-the-art missiles is much faster than the rest of the system states, a near-optimal solution is obtain ed to the BTT guidance problem using multiple timescale techniques. No nlinear feedback solutions for the acceleration command and roll-rate command are derived. The zero-order slow solution obtained by treating roll rate as infinitely fast, is exactly the optimal guidance law for a skid-to-turn missile. The zero-order fast solution provides the rol l-rate command. A first-order analysis corrects the acceleration comma nd for the finite dynamics behavior in bank angle. Simulation results are presented for a representative terminal engagement using this algo rithm. Near-zero miss distances are obtained in a noise-free environme nt.