The Human-body Response and Target Tracking Performance with Sighting Helmet in Vibration Conditions
WU Ming-lei;ZHAO Guang;WU Feng;WANG Xing-wei;XIE Hong;GUO Jin-yang;LI Shan-ming;CAO Yiqing;Institute of Aviation Medicine,Air Force;The 304 Institute,Corporation of China Aviation Industry;
Objective To determine the resonance frequencies of head with sighting helmet in vibration conditions, and measure the displacement of helmet slippage from head, and investigate the target tracking performance, so as to provide basis for the design and use of helmet. Method 6 healthy volunteers who sit in ejection seat. The helmet was mounted with sighting device or laser pointer. The seat was firmly mounted on the platform of vibration machine. Accelerometers were firmly mounted on the platform, seat, head and helmet. One end of a linear displacement transducer was firmly mounted on the face and the other end linked with helmet. There was a screen in the front of volunteer. In the screen there was a moving target. The sine scan vibration test was taken first to determine the resonance frequencies of head and helmet. The scan bandwidth was 2~110 Hz. Then, the sine vibration at the resonance frequency tests were taken to measure the displacement of helmet and the target tracking performance. Finally, the random vibration was tested. Result The resonance frequency of head and helmet is about 4.5 Hz.The displacement of helmet is from 0.5mmto 6.7mm, apparently affected by the vibration amplitude. The tracking errors and time-on–target(TOT) are affected by vibrations significantly. Conclusion The low frequency resonance of head with helmet has been keeping. The tracking performance is affected by vibrations significantly.