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TRACES
HOST SYSTEMS: SUN, SGI
PROGRAM LANGUAGE: FORTRAN 77
TRACES
simulates
helicopter air combat explicitly including helicopter
aerodynamics, missiles, guns, and avionics with incorporation
of the environment. The helicopter flight dynamic models
include a generic model characterized by state vector
containing roll, pitch, velocity, and body frame angular
rates. The missile model includes aerodynamics, guidance,
seeker, and fuzing and is characterized based on acceleration,
heading, and climb angle rates. The missile guidance model
allows proportional navigation, pure pursuit, and beam
guidance methods to direct the course of the missile and
calculate desired heading and climb angle rates. The missile
seeker model (active, semi-active, and infrared (IR))
specifies the type of signal the seeker detects and the field
of view (FOV) of the seeker. The missile fuzing model contains
fuzing conditions and patterns. The turreted gun model aims
the gun and tracks the target within the turret boundaries.
The avionics models include radar, identification friend or
foe (IFF), fire control, and IR, optical, and passive sensors.
The fire control model applies constraints for each weapon
type. The high resolution terrain database interface is an
important feature of TRACES and consists of the data
structures, calculations of the height over terrain (HOT), and
performing a line of sight (LOS) calculation between two
points.
In TRACES, the simulations
use event-driven controls, which provide a natural mechanism
for more realistic interactions among asynchronous processes
by executing the modules at varying rates determined by the
modules. A sequence of events of the same type is called a
“stream”. A stream of events effectively simulates both
continuous and discrete processes. The continuous process of a
helicopter flying along a trajectory is simulated by the
periodic execution of helicopter flyout events. As events in a
continuous stream end, the next event in the stream is
scheduled to make the stream self-perpetuating. Continuous
processes are executed periodically as in time-sequenced
simulations, but the interval between events in each stream
can be tailored. A discrete process, such as gun firing,
occurs at irregular intervals scheduled from some other event
and is not self-perpetuate. Sequences of discrete events are
determined by the simulated situation and are executed only
when needed.
All aspects of the engagement to be simulated are
specified from input data files. The scenario file specifies
initial engagement conditions including placement of
helicopters and equipment relative to each other and the
terrain origin. Also the input includes an unformatted binary
file, produced by a preprocessor program, containing data
associated with the coordinates and values characteristic of a
selected region. Library files containing physical and
functional data for variables associated with missiles,
helicopter models, weapons, and devices are required. A file
containing attributes of pilot behavior is also required.
Output data includes an echo file,
which is an image of the input data from the scenario, pilot
behavior, SAM, weapon, and device libraries, and can be used
in the debugging effort. A dedicated diagnostic output file
receives detailed information about user selectable modules of
the simulation code; this is controlled by a set of logical
flags in the input data so diagnostic output can be requested
or suppressed. The engagement summary files contain a complete
time history of aircraft and missile kinematics state
throughout the engagement, and important weapon effects such
as kills, firings, and detection. This diagnostic output file
optionally records standard data records that can easily be
read by statistical analysis packages. The summary file
supplies input data to a graphics postprocessor program, which
displays a full color terrain, map and replays the engagement
using icons.
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