Building a F-35 Vehicle Systems Integration Facility (VSIF) Data Acquisition System

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VSIF Data Acquisition System Configuration

Author(s):
Michael Fortenberry - G Systems, Inc.

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.

For more information, contact:

Dave Baker 

G Systems

Tel: 972-234-6000

E-mail: dave.baker@gsystems.com