The Netherlands is home to an ambitious project to build an advanced research simulator laboratory.
Graham Warwick/ATLANTA
A SIMULATOR IS taking shape in the Netherlands, which could set new standards for the fidelity of commercial flight-simulators. Delft University of Technology's International Centre for Research in Simulation, Motion and Navigation Technologies (SIMONA) will be used for fundamental research into flight simulation and, once completed, to explore the human-machine interface in future aircraft and spacecraft.
According to SIMONA director Sunjoo Advani, simulator fidelity is becoming increasingly important as regulatory authorities seek to ensure the "transfer of behaviour" between simulator and aircraft, and vice versa. Pilot reaction to an emergency, for example, should be identical in both aircraft and simulator, so that skills acquired on the ground are applicable in the air.
Any shortfall in simulator fidelity can result in the pilot learning responses, which are not appropriate in the aircraft. Fidelity can be compromised by the dynamics of the motion system, realism of the visual system or accuracy of the aerodynamic model, and these are areas, which will be tackled by the SIMONA programme.
Delft has a long history of flight-simulator research and contributed to development of the friction-free linear hydrostatic bearing now widely used in motion systems. The SIMONA programme was launched in 1992, says Advani, and the initial phase, just ending, has involved an investment of Dfl30 million ($18 million). Of that Dfl5 million, has come from the Netherlands Government. The rest has been, provided by universities and industry.
The first phase has involved the development of an advanced six-axis motion system. This is now ready for testing, says Advani. The design dedicates a digital signal-processor to each hydraulic actuator, enabling the system to compensate for variations in actuator performance resulting from hydraulic-fluid contamination, for example.
The SIMONA motion-system time delay is 20millisec, he says, compared with 80-150millisec for a conventional flight-simulator motion base. The bandwidth is increased, meanwhile, to 15-20Hz, enabling the system to generate harder, higher-frequency motion effects, "such as the touchdown bump", says Advani.
Next comes a lightweight, integrated flightdeck and motion-platform structure, or "shuttle" which will be mounted on the motion system later this year. This structure has a shell made from a sandwich of aramid-fibre skins and Nomex-honeycomb core, reinforced with carbonfibre reinforced plastic frames, floor beams and longerons to increase stiffness.
Advani says that the motion platform will weigh less than 3,500kg fully equipped with the visual system, flightdeck and crew, compared with 18,000-20,000kg for a conventional simulator. The centre of gravity is also lowered, to just slightly above the gimbal plane (compared to 2-3m above). Both contribute to improved motion-system fidelity, he says.
The SIMONA research simulator is scheduled to be operational "this time next year" without the visual system installed. Hewlett-Packard has donated a host computer and development of the rapidly reconfigurable flightdecks and the experiment-control station are under way.
High-performance graphics hardware will be used to generate rapidly two- and three-dimensional display formats for evaluation in the full glass cockpit. Easily interchangeable column columns and side sticks will be provided.
INSTRUCTION TASK
The experiment-control station will perform two functions, acting as an instructor station for the simulator while allowing the instructor to become an experimental subject. Studies will look at automating the instruction task, Advani says, and the feasibility of using off-board instructor-stations to manage multiple simulators engaged in realistic simulations involving cabin crew, air-traffic-control and other elements.
Delft has just submitted a request for Government funding support for the next phase of the SIMONA programme, the addition of a visual system. Several proposals have been received and include offers of industrial co-operation, Advani says. The image-generator is likely to be off-the-shelf, he says, but the display system will be purpose built.
The shuttle design provides an uninterrupted 180¡-horizontal by 40¡-vertical field of view. The wide-angle display will use a lightweight space-frame structure consisting of moulded carbonfibre tubes. Instead of the usual mylar-film mirror, pulled into shape by a vacuum, the curved display will consist of five to seven composite petals with laminated, mirrored surfaces, Advani says. The visual system is to be operational into two years' time.
Minimum weight is a key feature of the display-system design. "Motion performance is dependent on the inertia of the visual system," he says. "The motion cue is one of the most important," Advani says, explaining why so much of the SIMONA effort is on reducing the weight and inertia carried by the motion system. "A heavy [motion] platform can induce inappropriate behaviour in a pilot, particularly in smaller aircraft and helicopters," he says
Source: Flight International
