Dual-Control Guidance Strategy for Homing Interceptors Taking Angle-Only Measurements

Abstract

A discrete dual-control homing guidance law is proposed to improve intercept capabilities when angle-only measurements are available. A two-maneuver intercept is considered where the first maneuver inserts a measurable line-of-sight (LOS) rate to enhance the estimate of a key guidance parameter prior to the terminal maneuver used to null intercept miss. A numerical technique is proposed to evaluate the gradient of the variance of the chosen parameter with respect to a velocity correction. A first-order search is used to find a velocity correction that minimizes or substantially reduces the terminal variance. The algorithm is extended to multipleburn scenarios and is evaluated using the terminal estimation error in miss, velocity correction, and time-to-go, respectively, as the control criterion. The results yield interesting insights into the information content in the angle measurements. More importantly, they indicate that the dual-control guidance law suggested here could reduce rms angle-measurement accuracy requirements by a factor of 10 or more, compared to that needed by a more traditional guidance approach, while still maintining terminal intercept performance.