Abnormal visual-vestibular responses among aviation personnel may predispose them to spatial disorientation, loss of dynamic visual acuity, or airsickness. Past pilot referrals to the Naval Medical Research Laboratory (NAMRL) from the Naval Aerospace and Naval Operational Medicine Institutes (NAMI/NOMI) have revealed that certain pilots may be predisposed to experiencing spatial disorientation, but whose deficiencies were only detected via specialized experimental acceleration equipment and tests.
DSM’s new Vertical Linear Accelerator (VLA) was developed for NAMRL to meet two main clinical needs of the Navy: 1) to identify and transition suitable future visual-vestibular testing devices; 2) to identify and transition airsickness tests and desensitization protocols. Particular emphasis is placed on vertical linear oscillation stimuli to the otolith organs, which sense the kinds of oscillations common during challenging aviation or sea operations and which are less well understood than the semicircular canals.
The VLA system has a stroke of 12 feet (3.66m) total and the capability to reach 1 G (2g total force with gravity) acceleration and a maximum velocity of 14 ft/s. In order to maximize the value of the device to the NAMRL and the greater research community, the goal of the machine development is to make the device as smooth and as quiet as possible. This is accomplished in part by the use of brushless linear motors and air bearings as the primary mover and guidance components. The VLA will include an integrated dynamic visual acuity (DVA) tester and capability to run arbitrary waveforms. Also included is the use of a triple redundant safety scheme utilizing long travel impact bumpers, rail brakes and regenerative dynamic braking.
“There is the vertical linear accelerator, a device that oscillates pilots at two cycles per second (2Hz) like a salt shaker…”
“The US Navy says its new vertical linear accelerator, built with government small businesses innovation research funds, is complete and being installed at Dayton. The device has a chair with a display screen that travels up and down a 3.66m-long I-beam to study vertical motion environments, for instance in helicopter research. The chair can move at rates of up to 2Hz, exerting up to 2g of force on the subject. "A lot of the research is for helicopters and then some very specific things we might want to look at," says Simmons, adding that the device could be used to study visual/vestibular interactions for any vehicles "with vertical motion" - the F-35 VSTOL variant, for example.”