The military’s rapid move toward network-centric, IP-based (intellectual
property) architectures is driving a number of design considerations
for current and next-generation embedded commercial off-the-shelf
(COTS) subsystems deployed on unmanned aerial vehicles (UAVs).
The push toward network-centric architectures is speeding the adoption
of these platforms and of newer data communications interfaces
such as Gigabit Ethernet (GE) and serial rapid IO (SRIO). There’s also
growing discussion about migrating over to 10 GE in the future.
At the same time, practical budgetary reasons for supporting slower
legacy interfaces such as 1553 on the protocol level to protect software
application development investment encourages continued but
transitional support of earlier, slower aerospace interface standards.
During this period of transition away from legacy interfaces, UAV
system integrators have taken a “best of both worlds” approach by, for
example, supporting the simulation of 1553 over GE and other highspeed
interfaces. This encapsulation approach enables the system to
utilize the entire 1553 structure and retain the software hooks that
have already been built, tested, and qualified in flight applications.
In anticipation of future requirements related to network-centric
architectures, next-generation UAV subsystems are being built today
that incorporate the hardware piping that will support IP packetization
in the upcoming future. This anticipatory step, essentially laying
down high-speed “cables” while retaining support for application
code written in legacy protocols, will ease the transition into adopting
complete network-centric communications methodologies,
including support for IPv6, when budgets allow and requirements
demand the evolution.
As an example, Curtiss-Wright’s System Sensor Management Unit
(SMU) subsystem deployed aboard the Global Hawk UAV provides
a fully modern platform that can support GE and Fibre Channel links
while interfacing with legacy interfaces such as 1553. In this way,
the SMU works essentially as an interface fusion box, routing various
interfaces and fusing them together.
The SMU’s aluminum chassis has also evolved, adding significant
capacity for system expansion, as it has grown from the original
(utilized in Global Hawk Block 20) 44-lb box to its current 75-lb size
(planned for the BAMS Global Hawk). Helping to drive this evolution
has been an increased demand for modularity and scalability.
UAV system integrators are being called on to enable both the scaling
up and scaling down of particular subsystems as required by the
mission. This trend has driven designs that enable system elements,
such as solid-state hard drives, to be easily ejected to protect proprietary
data in case of damage or threat to the aircraft. Subsystems
for the BAMS variant of Global Hawk, for example, will likely include
these features.
Going beyond the idea of interface fusion, another new trend in
UAV subsystem design is the data-fusion requirement. In data fusion,