In this chapter, we present the fundamentals used in the analysis and design of terminal homing guidance systems. The purpose of terminal guidance is to cause a pursuer (typically a missile) to hit, or come close to, a preselected target.Moreover, we require that this interception take place despite unpredictable maneuvers of the target, disturbances, and navigation uncertainties.Here wemake a rough distinction between three types of terminal guidance: homing, ballistic, and midcourse. This distinction is based on the amount of control authority that is applied during most of the flight and does not lead to categories with sharply defined boundaries. Ballistic and midcourse guidance are studied in Chapters 6 and 7, respectively.

In homing guidance, we make the following assumptions:

1. The pursuer is actively controlled during the entirety of the engagement.

2. The pursuer has a velocity with constant norm (this is typical of the terminal phase of an engagement in atmospheric flight).

3. The pursuer is equipped with a passive seeker (e.g., a heat seeker), or a semipassive seeker (such as in laser-guided, smart bombs).

Under the preceding assumptions, we study solutions to the terminal homing guidance problem. We also allow the possibility of limiting the radius of curvature of the pursuer's trajectory.

Section 5.1 presents the fundamentals of planar homing guidance and identifies the main candidate strategies for homing.