Hypervelocity orbital intercept guidance using certainty control
Abstract
Terminal guidance of a hypervelocity exoatmospheric orbital interceptor with free end time is examined. A new approach called certainty control is developed where control energy expenditure is reduced by constraining the expected final state to a function of projected estimate error. Conceptually, the constraint produces a shrinking sphere about the predicted impact point with the radius being a function of estimated error. If the predicted miss is inside or touching the sphere, thrusting is not necessary. The interceptor is modeled as a satellite with lateral thrusting capability using twobody orbital dynamics. The target is modeled as an intercontinental ballistic missile (IBM) in its final boost phase prior to burnout. Filtering is accomplished using an eightstate extended Kalman filter with lineofsight and range updates. The estimated relative trajectory and variances are propagated numerically to predicted impact time and then approximated by splines, eliminating the need to propagate new data repeatedly when present conditions are varied. A search is then made for a new impact time and point that will minimize present interceptor velocity changes and final mass distance. This control strategy, which is applied to two intercept problems, substantially reduces fuel consumption.
 Publication:

Journal of Guidance Control Dynamics
 Pub Date:
 June 1991
 DOI:
 10.2514/3.20677
 Bibcode:
 1991JGCD...14..574A
 Keywords:

 Ballistic Missiles;
 Hypervelocity Projectiles;
 Kalman Filters;
 Satellite Interceptors;
 Terminal Guidance;
 Algorithms;
 Computerized Simulation;
 Flight Control;
 Impact Prediction;
 Line Of Sight;
 Spline Functions;
 Space Communications, Spacecraft Communications, Command and Tracking