Homing missile guidance and estimation under agile target acceleration

Two new algorithms for homing missile guidance and estimation in the two-dimensional intercept problem are proposed based on the assumption that certain targets execute evasive maneuvers orthogonal to their velocity vectors. The objectives of both algorithms are to estimate the engagement states in the presence of unknown target acceleration and guide the interceptor to hit the target based on these state estimates. Both algorithms are the integration of a filter in cascade with a guidance law, but constructed using different philosophies. One algorithm constructs the guidance law and the filter that estimates the target acceleration based on a target model in which the magnitude ofthe target acceleration vector is assumed to be a sinusoidal function. The other algorithm constructs the guidance law based on the anticipated worst possible target acceleration and constructs the filter by blocking rather than estimating the dynamic effect of the target acceleration. These two algorithms form an interesting design trade between the inherent estimation lag and increased estimation uncertainty.