"Heads Up" Display (HUD)

During target engagement by a high-performance aircraft, it is critical
that the man/machine interface be kept very simple.  There is no time
to scan the cockpit for flight information in close engagements, and
the pilot must watch the target at all times.

A solution to this problem is to create a "heads up" display (HUD) so
that the pilot may observe both the target and critical flight
parameters simultaneously. In most HUDs in aircraft, the flight
information is projected onto the windshield of the canopy so that the
pilot may continually look outside the aircraft. Figure 1 below shows a
typical HUD.  The HUD concept has been developed by the US DoD for some
time, and we are now finding this good idea filtering into the
commercial sector, with the window-oriented speed and status display
now emerging as an option on certain cars.

The object of the HUD is to provide sufficient information with low
complexity.  The correct scenario is for the pilot to fly the aircraft
so that the selected target falls within the target box.  Firing during
that time yields a high probability for a hit.  Assuming that the pilot
has selected a trainable gun (that is, one that may be aimed
automatically within a few degrees), the cursor inside the box points
to where the gun is currently aimed.  In addition, depending upon the
target range and type of armament selected, the target box will vary in
size, indicating the effective radius of the weapon.  As the aircraft
gets closer to the target, the box grows in size.  The display also
provides a presentation of critical flight parameters, such as altitude
and angle of attack, plus a summary of the armament status. 
Furthermore, an arrow is superimposed on top of the selected target. 
This arrow not only assures the pilot that the correct target is being
tracked, but also presents the target's predicted direction of flight.


In systems as complex as aircraft, there will exist many embedded
subsystems. When we design our HUD, there will certainly be physical
constraints on the solution that are beyond our control: we simply
cannot redesign the entire aircraft to meet our needs.  Most likely,
even before we start the design of our particular subsystem (the HUD),
another design team has already made a functional allocation of each
major aircraft subsystem, such as the avionics computer or radar
subsystem.  As a result, our HUD will have to depend upon several
predefined and usually static interfaces.

Figure 2 illustrates the functional allocation of the aircraft
subsystems from the perspective of the HUD.  As you can see, the major
subsystems are the Armament Subsystem, which controls weapon resources
and targeting, the Navigation Subsystem, which includes all flight
avionics equipment for aircraft guidance and control, and the Target
Radar Subsystem, which acquires and tracks target aircraft.

Problem [10 points]: perform an object-oriented analysis and a
top-level design of a HUD as described.  Create and present a data
dictionary, an entity-relationship diagram, and a data flow diagram
which illustrates your understanding of the problem as your analysis
phase.  Select the classes and objects during your design phase and
present the details of the member data and functions associated with
these classes and objects.  Include each subsystem interface in your
design along with the details of the interface.  Allow for subsystems
to be duplicated, so concentrate on a class-oriented design.