In the Navy

Two or three years ago, integrators would have laughed at the idea of controlling mission critical operations with Windows systems. Now the US Navy steers its ships with realtime embedded systems.

An integrated hardware and software solution has been selected by Litton Marine Systems for the rudder control system on US Naval Destroyers. The system, which runs on the Windows NT Embedded operating system, combines VersaLogic’s Panther PC/104-Plus single board computer with VenturCom’s RTX real-time enabling technology for Windows.

Litton Marine’s RTX-based rudder control system contains four VersaLogic embedded Pentium computers networked via a dual Ethernet connection, and operates on Windows NT Embedded. This design platform provides a robust user interface, a common development and testing platform, and integrates a number of pre-written off-the-shelf Windows-based applications.

Litton Marine Systems, a division of Litton, was commissioned to develop the rudder control system for the U.S. Navy’s upcoming Mustin (DDG 89) and Chafee (DDG 90) Destroyers, currently under construction at Ingalls Shipbuilding in Pascagoula, MS and Bath Iron Works in Bath, ME.

Destroyers, commonly referred to as ‘greyhounds of the sea’, are fast warships that help safeguard larger ships in a fleet or battle group.

Because they need to manoeuvre swiftly, the ability of the ship’s steering system to respond quickly to navigational commands is a paramount requirement.

The project’s architecture calls for four embedded controllers residing in the steering compartment of the ship. Two primary controllers are used to run the twin hydraulic systems that control the two rudders on the ship. The other two controllers are redundant, and are used as backup. Any controller can serve as the master controller and can communicate with numerous local consoles found throughout the ship.

Litton Marine began work on this project using a traditional RTOS development environment. However, they soon realised that a number of system requirements could not be adequately met through the use of their existing operating system.

At that time, Windows NT had begun to gain visibility as a development platform for embedded applications. The engineers at Litton Marine recognised a host of potential benefits that could be derived from building the system in a Windows NT environment.

These included:

A common development and testing platform — The ability to both develop and deploy the system using Windows NT tools improves the overall efficiency of the development, test, and debugging processes.

A wealth of easily integrated off-the-shelf tools and pre-written device drivers — Enables system engineers to add needed functionality to their designs while reducing the length of the development cycle.

A more robust user interface — Windows NT enables the user to add input/output devices including keyboards, monitors, and printers. This capability provides better overall system visibility, offers an enhanced system reporting mechanism, and provides a common environment between the system’s controllers.

Ability to link dual Ethernet connections through a single computer — To ensure redundancy in the event of an emergency, Litton Marine’s system required the support of dual Ethernet connections through a single computer. Windows NT offers this capability, which had previously been unavailable from the solution.

All these advantages would result in significantly lower development costs, and quicker time to market.

However, the Windows NT operating system could not, by itself, ensure the 40 Hz performance rate required to control the motion of the ship’s rudder effectively. A quick search of available technology, and a visit to Microsoft’s Web site, highlighted RTX, VenturCom’s real-time enabling technology for Windows NT. Litton Marine discovered that RTX could provide the guaranteed timing control and real-time determinism required to successfully deploy its rudder control system across Windows NT. Throughout the development process, Litton Marine has become quite impressed with RTX’s overall ease of installation and implementation, reliability, and cost-efficiency. This application is slated for future Destroyers as well as the Navy’s Amphibious Transport Docks (LPD), which are ships that transport amphibious vehicles to shore.

Under an agreement between VenturCom, and VersaLogic VenturCom has created configurations which speed the development of real-time Windows NT and Windows NT Embedded-based systems across VersaLogic’s PC/104-Plus and EBX single board computers.

Tom Barnum, General Manager at VersaLogic, said: ‘Customers of ours, such as Litton Marine, have demanded a PC/104 single board computer solution that supports real-time operation with Windows NT Embedded. Partnering enables us to meet that need.’

VenturCom’s website is at