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MoD moves to open architecture in order to embrace modularity

The electronics industry is no stranger to the concept of open systems; where either an official or a de facto standard allows technology from a range of suppliers to interoperate with few issues.

But when it comes to military equipment, the concept of open systems has only been adopted recently. Before, specialist suppliers maintained proprietary standards and only they could augment equipment which they had provided.

Today, those specifying and buying military equipment are keen on open systems. The approach not only reduces costs, but also promotes compatibility.

So if your ambition is to supply equipment to the UK military, you need to conform to the requirements of the Land Open Systems Architecture (LOSA). LOSA is a high level architecture that brings together such domains as vehicles, dismounted soldiers and static bases, along with Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR).

It comprises three parts: the Generic Vehicle Architecture (GVA), the Generic Base Architecture (GBA) and the Generic Soldier Architecture (GSA).

The objective of the GVA, or Def Stan 23-09, is to create a single, standard digital electronic and electrical architecture for UK military vehicles (see fig 1). It also addresses the need for a standard human-machine interface (HMI). The approach builds on the Vehicle Systems Integration programme and on the Vehicle Technology Integration Demonstrator.



GBA, as defined in Def-Stan 23-13, is a similar standard that defines interfaces to power, data, water, waste and fuel. GSA, meanwhile, identifies the critical interfaces and constraints and specifies the standards to be used when designing equipment for the dismounted soldier.

Professor Bryn James is a senior fellow in the Defence Science and Technology Laboratory's physical sciences department and an expert on the GVA. He explained the thinking behind the approach. "The MoD started to put LOSA together for a number of reasons, but basically so it could take a platform view; making everything plug and play, modular and adaptable. It allows things to enter service more quickly, to be updated, replaced and repaired more quickly."

Def-Stan 23-09 outlines the thinking behind GVA. 'The purpose of Def-Stan 23-09 is to enable the MoD to realise the benefits of an open architecture approach to Land platform design and integration, especially in regard to platform infrastructure and the associated HMI, in order to improve operational effectiveness across all Defence Lines of Development, reduce integration risks and reduce the cost of ownership across the fleet. This is achieved by mandating and applying the appropriate interface standards'.

GVA is also applicable to what the MoD calls the 'full spectrum of land platforms'. The requirements not only address equipment to be fitted as part of the initial operating capability, but also those likely to be fitted through life.

Prof James said it was difficult to say when the LOSA initiative started, but noted it was motivated by much defence equipment being bespoke in nature. "GVA is the more developed [of the three architectures] and is available for download at www.dstan.mod.uk.

"Within GVA, part 1 looks at infrastructure issues and that contains everything related to connectors for communications and power systems – Ethernet, USB, optical and so on. Part 0, meanwhile, covers the philosophy behind GVA. It doesn't just specify, there's also a dialogue and a discussion on the topics."

In fact, GVA has nine guiding principles, including:
• to be applicable to current and future systems;
• to use open, modular and scalable architectures and systems;
• to facilitate technology insertion; and
• to not implement in hardware any functionality that could be implemented in software.

When it comes to the electronic infrastructure, the GVA mandates that it shall consist of:
• One or more LANs for non deterministic data and video distribution;
• Connectors, including USB for peripheral devices only;
• Time stamp service to RFC5905;
• DDSI wire protocol with the Land Data Model;
• Video, using Def Stan 00-82;
• Safety critical deterministic networks, using time triggered protocols where appropriate.

Local area networks are expected to use Ethernet technology and to be capable of handling data rates of 1Gbit/s, with connectors and pin outs specified. A single Ethernet connection, for example will use MIL-STD 38999 series III connectors, with either the N or A keyway polarisation selected to support the appropriate security classification.

GVA also allows for the use of fibre optic communications, with data rates of up to 10Gbit/s. Again, the connector is specified, as is the keyway polarisation for security. MIL-STD 38999 connectors are also specified for USB purposes.

With more and more electronic equipment being integrated into military vehicles, it's no surprise that the GVA has a lot to say about power supply: '28V DC shall be the primary supply voltage for platform installations. It shall be the responsibility of the platform integrator to provide outlets with the appropriate individual power protection'.

It then says that a power conditioner may be needed to stabilise voltage, filter input and output supplies and to improve transient response.

'Power conditioning shall be incorporated within the power system units – for example, the power management unit, outlet points and power inputs – unless this causes integration issues, in which case the power conditioning unit shall be a central self contained unit'.

The standard also notes that vehicles implementing the GVA should not be affected by EMC issues. Given the requirement to exchange subsystem equipment between platforms, it says, it is important to guarantee minimal levels of emission to ensure compatibility when exchanging equipment.

Recognising the high levels of stress involved when a vehicle is being used 'in anger', GVA requires the HMI design to be intuitive so the crew can use it under stressful conditions. Information presentation must be unambiguous, it adds. 'The HMI shall be designed such that the user can control the vehicle's subsystems to the required level of performance, while the vehicle is moving over the full range of terrain types on which it will operate'.

The GVA is also interested in data collection, specifying that vehicles should include a Health Usage and Monitoring System, or HUMS. Part of the approach here is to log failures and to predict whether a unit might be failing. In the latter case, the HUMS unit must inform the crew of the useful working life of critical systems. The HUMS unit is also required to gather x-y-z acceleration data when those values exceed 4g.

Prof James said that GVA continues to be 'work in progress'. "We want GVA to do more," he enthused, "and we want to include more areas. For example, we are doing work in bringing hydraulic and pneumatic systems into the Architecture."

Foxhound the first to meet GVA requirements
The Foxhound light protected patrol vehicle is the first British military vehicle to meet the MoD's Generic Vehicle Architecture requirements. The objective of the GVA is to create a single, standard digital electronic and electrical architecture for UK vehicles that will enable the vehicle's crew to manage power and handle data efficiently.

Foxhound is said to be suited to use in narrow backstreets. Weighing 6tonnes and with a top speed of 70mph, it accelerates to 50mph in 19s. With four wheel steering, Foxhound has a turning circle of 40ft.

Author
Graham Pitcher

Related Downloads
66408\P29-30.pdf

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