A pneumatic servovalve and control system have been integrated into a precision three-axis, motion-base simulator. A Pentium III 500-MHz PC, which connects with the joystick and rudder pedals, allows the user to play numerous PC games and flight simulator packages such as Microsoft's popular Flight Simulator 2000. An 18-in. LCD monitor displays the images and a 50-W base speaker underneath the chair base provides realistic sound.

A key component is the servovalve from Cobra Technologies, Irvine, Calif., which features high flow rates and broad bandwidth capability (nearly 200 Hz). Two 0.125-hp pneumatic airbrush compressors power the chair. Operating pressures range from 30 to 40 psi.

An operator-controlled flight yoke or joystick controls ±30° of pitch and roll axis motion. Rudder pedals provide ±15° degrees of motion control for the yaw axis.

A recent software upgrade to the chair's flight simulation capability includes the ability to fly FlightGear open-source software (www.flightgear.org) a realistic Linux-based closed-loop flight simulation package featuring a USB interface. Software "hooks" in the FlightGear software provide real-time pitch, roll, and yaw aircraft flight angles. These digital output signals, through a 12-bit d/a converter, drive the servovalve/actuator assembly. This ensures accurate and responsive motion synchronization and realistic simulation. http://www.menet.umn.edu/~curt/fgfs/Projects/fschair.html