OPTIMAL ORBITAL RENDEZVOUS MANEUVERING FOR ANGLES-ONLY NAVIGATION

Angles-only navigation has great potential for orbital rendezvous, satellite formation flight, and other relative motion applications but is often discarded because of its inherent and misunderstood limitation in determining range. In most practical applications, maneuvers are needed to help resolve the relative position between two or more orbiting vehicles. Unfortunately, any arbitrary maneuver will not suffice. Maneuvers that strategically alter the natural line-of-sight (LOS) measurement profile are required with different trajectories producing varying degrees of observability. Using a previously derived closed-form observability criteria, the concept of having levels or degrees of observability is formally defined as a function of the measurement error. With this analytical expression, a mathematical foundation is formed to derive optimal maneuvers that maximizes the observability of the relative state. Although the results are valid for any linear dynamic system where azimuth and elevation measurements are used to estimate the relative position and velocity, a detailed orbital rendezvous example is provided to illustrate the fundamental concepts in deriving optimal maneuvers for angles-only navigation.