ability to gather information about or to alter the state of the environment in which the

platform is operating. Therefore, the mission isolation constraint is intended to allow the

engineer to construct systems that can support a variety of missions, not just a single one.

The computer hardware independence constraint insists that the component be designed

independent of the computer system upon which the component will run. This was

included in the architecture so that currently used components can be applied to future

computer systems without modification to the component. This allows new computer

architectures to be easily inserted into current systems, extending its life cycle. This also

allows for hardware flexibility, as the appropriate hardware may be applied to each

system. Finally, technological independence is similar to computer hardware

independence, but instead deals with the action to be performed by the component instead

of the system that is performing the action. This constraint basically states that the

architecture will make no assumptions concerning the method by which an action is

performed. For example, in a JAUS compliant position system, no assumptions are made

concerning the method in which the vehicle position is obtained. Any method of

obtaining vehicle position is allowable, from a Global Positioning System (GPS), dead

reckoning, inertial measurement, a vision based position system, or any subsequent

positioning system [10].

1.3.2 System Topology

 There are four elements, which comprise the hierarchy of the JAUS architecture: the

System, Subsystem, Node, and Component/Instance. A System is a logical grouping of

one or more Subsystems, which have been grouped such that beneficial cooperation

between the Subsystems can be achieved. A Subsystem is a distinct organism, which is

comprised of any number of Nodes necessary to form a complete unmanned system. A