http://www.sgi.com/International/UK/stories.dir/britaerosp.html (Einblicke ins Internet, 10/1995)
The challenge facing the avionics engineers who shape the cockpit
environment is to create a format that helps aircrew complete tasks as
quickly and effectively as possible.
British Aerospace's Cockpit Group, within the Company's Systems Engineering department at Farnborough, employs a number of experienced specialist engineers to look at ways in which a pilot's work can be facilitated. The Group includes experts on ergonomics who are responsible for integrating the needs of the pilot into the overall cockpit design. There are also technical experts, including display performance engineers, knowledge engineers and software developers. This unique combination of expertise bridges the gap between psychology and technology with the aim of increasing the performance of individual pilots in the next generation of combat aircraft.
A Demanding Application
One particular focus of the work of the Cockpit Group is digital map displays, one of the more demanding applications associated with geographical information systems (GIS). Map displays have come a long way since the days of paper maps and the time when a pilot had to leaf through an assortment of maps while preparing to descend and bomb a target, verifying his own and the target's positions while at the same time keeping an eye on the dials in the cockpit are long gone.
The development of a moving map display that projected an image of the
relevant map onto a screen in front of the pilot, improved the
situation and is still used in many aircraft cockpits. However, this
approach is unwieldy since several rolls of film are needed for a
single flight, and to move from one map image to another the pilot has
to spool backwards or forwards along the roll. This is a
time-consuming and distracting task during any combat mission.In
response to the need for a more flexible system, digital maps--displayed electronically on a
computer screen--were
developed.
Using sophisticated computer graphics systems from Silicon Graphics, the Cockpit Group at British Aerospace has developed the world's first real-time digital maps. In effect, these form the prototype of a complete airborne computer-based geographical information system (GIS). The group is currently using Silicon Graphics Iris Indigo R4000 Elan for all its development work.
"[Silicon Graphics offers] the only machine that combines high quality graphics capabilities with low cost and suitably small size. Its powerful processor means that we can manipulate the various display options in real time. If you are travelling at 450 knots, even a few seconds taken by a computer to change and update displays is too long," explains Ian White, systems engineer at British Aerospace.
Designed to Avoid Confusion
The geographical information and display system developed by White and his colleagues has been specifically designed to avoid confusion arising from a cluttered screen and an overload of features. "At this stage in our development work we are, of course, working with simulated displays in the laboratory. It would not be cost-effective to carry out the exercise in a full cockpit simulator or to use a higher end workstation - so the Silicon Graphic system is perfect for our needs. The quality of graphics is excellent and the processing power does not limit our concept development in any way. In addition it is so compact that it could - given adequate protection - be placed inside an aircraft cockpit," says Ian White.
The basic map display of the present system resembles an Ordnance
Survey map but has additional information superimposed onto it, including
airfields and navigational landmarks. "The Silicon Graphics workstation enables us
to demonstrate the system in real time, so prospective customers can
evaluate its potential accurately. As the system is working exactly as
it would be in a cockpit, pilots can relate to it more easily and
provide us with valid comments and suggestions during simulation,"
according to British Aerospace's Ian White.
The pilot can also, in real time, view any section of the basic map in 3D relief, either from his own viewpoint or from the imaginary viewpoint described above. Features of the original map, such as roads and railway lines, can be overlaid onto the basic relief map.
The display incorporates an inter-visibility feature which allows the pilot to scan a visibility line from his own position. This indicates exactly what is in his line of vision or line of firing. He can then ask the display to indicate the area within which his own aircraft will be visible to a given target, with the objective of avoiding this area. The target could be another aircraft, a surface-to-air missile site, or a tank battalion, for example.
"In a practical situation," suggests Ian White, "The inter- visibility feature would have to be integrated with a weapons systems database, so that the marked area on the display would show the exact range of the target's weaponry".
The basic Ordnance Survey type map can also be displayed as a terrain map, viewed either from above or in sections through the terrain. Such maps, based on satellite photographs scanned into the system, could be particularly useful in planning a mission in that they would simulate as closely as possible the actual view seen by the pilot from his aircraft. Realistic conditions corresponding to the appropriate time of day can be incorporated into the display.
"The realism that the Silicon Graphics system gives us is vital. Integration of this type of display with a flight simulator allows the pilot to plan his mission in advance down to the last detail," says Ian White.
Lighting the Way
The Cockpit Group has also used the powerful graphics capabilities of the Silicon Graphics system to address problems associated with lighting of the display. In a practical situation, the usefulness of the display to a pilot would be affected by factors such as the reflection of ambient light off the screen. This has the effect of reducing contrast. At the same time, varying ambient light conditions cause adjustments in the human eye which in turn affect perception of a screen display.
The visual formats to be incorporated into the system under development had to take all these factors into account. To counteract effects of glare and varying light intensity, a dimming feature was added. This proved to be far from straightforward, since the relative conspicuousness of features, and contrasts between colours, had to be maintained irrespective of the light conditions.
"The graphics capabilities of the Silicon Graphics workstations are superb and have helped us move the project forward in a unique way," says Ian White. "These displays are not only realistic but can be manipulated in real time. This allows us to analyse the pilot's tasks and to carry out rapid prototyping of new ideas. The Silicon Graphics systems have allowed us to try out new ideas quickly with a low cost penalty, giving our project a big advantage."
