Guidance, navigation, and control from instrumentation to information management

I. Classical Guidance, Navigation, and Control Systems T HE classical guidance, navigation, and control (GN&C) system, shown in Fig. 1, is a feedback system that includes three subsystems. These subsystems are defined as follows. Navigation is the determination of the position and velocity vectors of a moving platform in a specified coordinate frame. Guidance is the determination of a trajectory from a current position and velocity to a desired position and velocity, satisfying specified costs and constraints. Control is the determination of the commands to the vehicle actuators to implement the trajectory, preserving a stable feedback loop.