An Objective model represents the desired state of the aircraft. Objective model state values are computed by any number of Guidance Mode components. These values are compared to estimated actual state represented in Navigation Models by Guidance Comparator components in order to Effect flight.
Although they are conceptually very different, the structure and dynamics of Objective models must parallel that of principal navigation models so that Error Models may reflect their differences in a consistent fashion.
Represent the visible attributes of topmost Objective Models as state vectors, using the same, or Transformable, representations used in Navigation Models. While the Flow of information in maintaining objective model state must parallel that for navigation models, most of the details are different. Rather than estimating values from sensors, objective models use Update protocols with Filters that select and/or combine values from various connected Guidance Mode components, that serve the same role as staged estimators in navigation. Often, the set of armed (enabled) modes established by system Monitor and Control components provide non-overlapping state data (e.g., lateral position versus altitude), so only a single source will be armed for any single state value. As with estimation, there may be an arbitrary number of intermediate stages.