The Challenge:
Developing an integrated system to acquire various types
of data including analog, digital, video, and additional data transferred from
other systems through reflective memory to be used by Lockheed Martin
Aeronautics in the F-35 Vehicle Systems Integration Facility (VSIF) to monitor
aircraft subsystems integration tests.
The Solution:
Using custom software developed by G Systems along with
National Instruments hardware and other third-party tools to create a system
that exceeds the initial requirements for the system.
Building the System with NI DAQ Boards
G Systems, Inc. was
contracted by Lockheed Martin Aeronautics to construct a F-35 Vehicle Systems
Integration Facility (VSIF) to monitor aircraft subsystems integration tests.
The VSIF system was distributed across several servers to enable load balancing
and achieve the required system performance. The distributed software
architecture, which included six major custom applications, provided for future
expansion of the system.
We performed analog and digital data acquisition
using five PXI chassis populated with a variety of NI data acquisition (DAQ)
boards to achieve a system total of 640 analog channels and 480 digital
channels. The ability to mix-and-match different types of DAQ boards while
maintaining time synchronization was important to control the overall hardware
costs for the system. The system maintained the time synchronization through the
use of an IRIG time signal provided by the VSIF data acquisition or another
source within the VSIF lab. The system used this time source to provide the
start pulse and 10 MHz clock, which was routed through the PXI-6653
synchronization boards to each PXI chassis.
The application that acquired
the analog and digital data also performed the following operations using an
external DC source controlled by GPIB:
- PXI board verification and internal calibration
- Signal path calibration
This automation of the signal path calibration allowed a system
verification to be performed automatically within 20 minutes. In past similar
systems, this type of operation could take several hours and required
significant operator interaction. The system delivered all data to the user in
engineering units (EU) and took into account the calibration values for the A/D,
signal conditioning module, transducer, and zero nulling values where
appropriate. Derived channels (i.e., channels that are calculated from
information contained in other channels, like Watts=Volts*Amps) could also be
calculated. Additionally, there was a defined interface to link user-defined
external DLLs into the system (without recompiling the software) to create more
complex derived channels.
System Configuration and Data Display
The system stored configuration information for the VSIF data acquisition
system in a relational database. We developed a custom graphical user interface
used by the system administrator to configure every system aspect. Some of the
abilities of this program included:
1. User management :
- Administrating eight levels of user privileges for the system
2. Hardware inventory
- Managing available hardware such as PXI boards and transducers
- Updating calibration information and date for all equipment
3. System configuration
- Managing current hardware connections
- Identifying user-defined derived channels
4. Data administration
- Archiving or exporting data and database to tape or other media
- Cleaning up unused data in database
5. Reports
- Creating several standard reports of system or channel configuration
(including historical data on calibration)
- Providing capability to add new user-defined reports
We designed the application to help the system administrators handle the
large channel count of the system by providing capabilities such as column
sorting and filtering, channel group definitions, multi-record editing, and
copy/paste functionality. Through the user permissions, any user could use this
application to view the system configuration, but only authorized administrators
could change values. In addition, we provided several administrator permission
levels to give users precise definition of privileges.
Because the VSIF
data acquisition system was used by many different groups to test various
aircraft subsystems during integration tests, a single static user display was
not a good solution. Instead, G Systems created a dynamic user-configurable data
display application so any user could create custom views of data with several
choices of indicators available.
This application supported advanced
navigation functions for a user to instantly review data in real time or recall
and view logged data from previous test runs. Users could set triggers and
alarms to quickly find data points of interest. The system stored all
information for an individual user configuration in the database, and this
information could be exported with test data for stand-alone review or playback.
This made it possible for a user to take a snapshot of test data (including all
calibration and transducer information) from several test runs and use it
independently of the main VSIF data acquisition database, which could be useful
for offline analysis or a group presentation.
The test
control/monitoring/playback application provided several modes of operation for
a user. The system constantly acquired data and published it in a low resolution
form to six client workstations. As the published data was received, it was
continuously buffered on the local client in a 30 minute rolling buffer. From
this buffer, a user could look back in time at data that was published or logged
and replay it in real time, if desired.
When the operator chose to log
data, the high resolution data was logged to file and was later transferred to a
central repository. These test runs could be downloaded from the repository to a
workstation for detailed review of the data in the playback mode. Again, the
user could play back the data in real-time or could navigate through the logged
data timeline using several navigation options.
The VSIF system
controlled and protected all logged data. The system data automatically moved
the data from the acquisition servers to a central data storage unit (RAID) when
a user started logging a test run. Users could freely review the test data but
were prohibited from deleting any test data from the RAID. Both the data display
and data analysis export application could directly call up data that existed
either on the RAID or in an archived dataset. As a result, relatively unskilled
users could easily review previously logged data with a minimal amount of VSIF
specific training.
A custom application DIAdem data interface (DDI) provided advanced analysis
capabilities in the VSIF data acquisition system. DDI leveraged all of the
database interface and engineering unit conversion functionality developed for
the data display application to feed data directly into DIAdem through an OLE
interface. The application was structured so the operator could easily select
the test run(s) and channel(s) to export to DIAdem and support merging of data
from several test runs.
A Practical, Effective Solution
Through the use of advanced
software architecture and NI hardware, G Systems was able to provide Lockheed
Martin Aeronautics with a highly-configurable, expandable system to meet current
and future requirements of the F-35 VSIF. The expandable nature of the NI PXI
platform also enabled expansion of the channel count by 60 percent over the
initial system requirements.
