DIAL-READING PERFORMANCE AS A FUNCTION OF FREQUENCY OF VIBRATION AND HEAD RESTRAINT SYSTEM.

Dial-reading performance under vibration was investigated at 6, 11, and 15 cps, 1 Gx acceleration vector of gravity plus or minus 1.1 gx vibration with three X-axis head restraint configurations a rigid restraint system, a piston-spring damper system and a spring only isolator system and two Z-axis head restraint configurations head locked in Z-Axis and head allowed to move freely in the Z-axis. Ten subjects were tested. The results indicated that less decrements in performance occurred at 6 cps than at 11 and 15 cps. Further, the use of the X-axis piston-spring damper isolation system resulted in significantly less errors as compared to the X-axis rigid restraint system. At 15 cps, where all three X-axis head configurations could be compared, there was no difference in performance with the piston-spring and spring only systems, while both resulted in less errors than the rigid system. Finally, the Z-axis restraint system had an effect upon performance only at 15 cps. The data suggested that allowing the head to move freely in the Z-axis at 15 cps resulted in less errors than when the head was locked in the Z-axis. Author