Basic Principles of Homing Guidance

25­ INTRODUCTION The key objective of this article is to provide a broad conceptual foundation with respect to homing guidance but with sufficient depth to adequately support the articles that follow. During guidance analysis, it is typical to assume that the missile is on a near-collision course with the target. The implications of this and other assumptions are discussed in the first section, Handover Analysis. The next section, Engagement Kinematics, establishes a geometric foundation for analysis that is used in the subsequent sections of this and the other guidancerelated articles in this issue. In particular, a line-ofsight (LOS) coordinate frame is introduced upon which the kinematic equations of motion are developed; this coordinate frame supports the subsequent derivation of his article provides a conceptual foundation with respect to homing guidance upon which the next several articles are anchored. To this end, a basic geometric and notational framework is first established. Then, the wellknown and often-used proportional navigation guidance concept is developed. The mechanization of proportional navigation in guided missiles depends on several factors, including the types of inertial and target sensors available on board the missile. Within this context, the line-of-sight reconstruction process (the collection and orchestration of the inertial and target sensor measurements necessary to support homing guidance) is discussed. Also, guided missiles typically have no direct control over longitudinal acceleration, and they maneuver in the direction specified by the guidance law by producing acceleration normal to the missile body. Therefore, we discuss a guidance command preservation technique that addresses this lack of control. The key challenges associated with designing effective homing guidance systems are discussed, followed by a cursory discussion of midcourse guidance for completeness’ sake. Basic Principles of Homing Guidance