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Saab elevates testing of the world’s most cost-effective fighter plane

06 April 2018

Saab Aeronautics needed to find a commercial off-the-shelf (COTS) solution to replace its custom system for interfacing to line-replaceable units (LRUs) in Saab Aeronautics simulators.

Gripen E Fighter System (Copyright Saab AB)

It reduced cost and ensured maximum flexibility by joining NI in piloting its Switch Load and Signal Conditioning (SLSC) system, rather than developing a custom system to interface to the preferred CompactRIO and PXI-based systems.

In the Aeronautics Division, located in Linköping, Sweden, the Gripen Fighter System is a key product for Saab Aeronautics. The Gripen is a unique fighter concept that balances operational performance, sophisticated technology, industrial partnership, and cost efficiency in a single, smart multirole fighter system. 

Saab Aeronautics are currently developing a new addition to the Gripen family, the Gripen E. This plane will feature the latest avionics technology, improved radar systems, and more advanced communication of important combat information between fighters. 

The HIL application

To help develop the fighters, Saaab are building simulators and rigs for its hardware-in-the-loop (HIL) systems to test various Gripen line-replaceable units (LRUs). These LRUs include flight control systems, tactical systems, sensors, and other avionics equipment. In its most complex tests, up to 40 interconnected LRUs must be tested together. It began looking for a suitable commercial off-the-shelf (COTS) product to use as an I/O system in its HIL systems and selected the NI PXI and CompactRIO platforms because they are both modular and easy to expand. This is advantagous to its systems, which often have many different signal types. Saab built its HIL system based on several CompactRIO systems, controlled using LabVIEW, in which it can easily add more CompactRIO devices when required. 

An HIL system lets Saab check that the LRUs work as expected by simulating the real-world environment it would run in. This lets Saab run many LRU tests without putting a fighter in the sky, which can be costly and potentially dangerous. In its HIL system, it used the CompactRIO to produce simulated signals for the LRU and receive the output from the unit.

Switching, loads, and signal conditioning

To make the system specific to its application Saab needed custom signal conditioning and functionality between the CompactRIO and the LRU. Saab did not immediately find a COTS solution for customised signal conditioning along with switching and applying loads, so it started an internal development project to integrate the NI equipment with its simualtors.

During this project Saab met with NI staff for an overview of the Switch Load and Signal Conditioning (SLSC) system. The SLSC solution extends PXI and CompactRIO measurement hardware with high-power relays for signal switching, power loads, and additional in-line signal conditioning capability. The system consists of a chassis with built-in active cooling capable of hosting 12 modules that can be used in applications such as Saab’s HIL testing. 

SLSC System at Saab

The SLSC system looked interesting and similar to the one Saab were developing internally. It also made creating the system easier for Saab as NI is a preferred supplier for the company already. By having NI define the ecosystem or “constraints” for switches, loads, and signal conditioning targeted at HIL applications with the NI platform, it could potentially lower costs as Saab would not need to spend time and effort defining them. It put its internal system development on hold to go with the COTS SLSC system. 

Saab can choose from a variety of third-party SLSC modules, create its own or contact third parties to build modules based on a detailed hardware and software development kit and design specifications from NI. This fits well with Saab’s custom needs, and it’s are following all of these paths. Saab created its own modules by working with a local developer called Syncore Technologies AB. As they are also based in Linköping, they can develop modules much faster, which is a huge advantage to.

Saab can use the intellectual property from some of its existing designs quite easily using the SLSC Module Development Kit and design guidelines. It worked with NI to outline its requirements and partnered with aerospace domain experts and NI Alliance Partners, Bloomy Controls and SET GmbH, for modules.

Benefits of SLSC

Saab can use the SLSC system to focus on developing custom circuitry following the constraints defined by NI in the SLSC standard to save time and development resources. Without the SLSC Saab may have needed to spend thousands of man hours and many thousands of Euros in materials to develop the system itself. It would have had to consider the cooling, the form factor, connectors, and more to create a custom signal conditioning system. 

Having a COTS product means Saab can contain development and maintenance costs promoting the Saab initiative to break the cost curve. Using the SLSC system further promotes the goal to focus the attention on building HIL test systems and rigs, not developing advanced hardware. 

Future plans

Saab have already begun plans to integrate SLSC into one simulator. Although it is a large project, never done before, and with challenges, it is moving forward. With the savings from using a COTS system from NI, Saab plan to use CompactRIO and SLSC in a number of new simulators in the near future to continue testing innovative functionality for the Gripen fighters in a short timeframe and hitting the goal to lower the cost of test.

Recently, the Gripen E took off on its maiden flight over southern Sweden. It was a big success and another great milstone in Saab’s aviation history. It will begin to use its SLSC-based simulator to refine the Gripen E’s LRU systems further for delivery of the first aircraft in the next few years.

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