Optimal terminal guidance with constraints at final time

A suboptimal terminal guidance law for a tactical guided missile was derived using a system of state equations describing the geometric and dynamic conditions of the missile-target closure. The problem was formulated to minimize a linear quadratic performance index with constraints at final time. Initially, the autopilot implementation assumed an ideal instantaneous response. This assumption was then removed, and the resulting configuration was investigated for various lag times. As would be expected, the control laws derived with the simplifying assumptions removed were much more complex. However, it was noted that in the limiting case, when the autopilot time lag tended to zero, a simpler control law surfaced. Comparisons were made then of the miss distance and attitude angle at impact with varying lag conditions. It was determined that the suboptimal control law was extremely sensitive to various approximations, especially linear subarcs or constants, for the time varying gains.