Centrifuge testing measurement study on the stability of pilot integrated display helmets

Objective To establish centrifuge testing measurement on the stability of pilot integrated display helmets, we investigated the objective and subjective movement data of the helmet under the sustained + Gz environment. Methods Twelve healthy male volunteers were randomly and averagely divided into 2 groups according to random number table: group A and group B. There were two types of the integrated display helmets tested: type A and type B (included BⅠ and BⅡ). Type A helmet was tested by group A. Type BⅠ and BⅡ helmets were tested by group B. The different type helmet tests were performed in different trapezium curve profile preconfigured. Onset rate was 3 G/s. The G peak value duration was 10 s. The test loads for type A were 3.5, 4.0, 5.0, 5.5 and 6.0 G. The test loads for type BⅠ were 3.5, 5.0, 6.5, 7.0 and 8.0 G. The test loads for type BⅡ were 3.5, 5.0, 6.0, 6.5, 7.0 and 8.0 G. A video camera was fixed in front of the subject in the centrifuge gondola and recorded the movement of helmet. The software SigmaScan Pro was applied for computing the slippage displacement of helmet under different + Gz conditions. At the same time, the movement scale in field of view were reported by subject and digitized. The SPSS 19.0 was applied for correlation analysis between objective data, subjective data and G level. Results The objective displacement and subjective movement scale of 3 types helmet were positively correlated (r=0.847-0.994, P<0.05) with G level respectively, and were positively correlated (r=0.542-0.602, P<0.01) with each other. Conclusions The pilot integrated display helmets displacement objective data, acquired by author's centrifuge tests, could reflect accurately the field of view change and was positively correlated to G level. The measure can be applied to assess the helmet stability in acceleration environment and provide test measurement for design, improvement and judgment of the same type equipment. Key words: Head protective devices; Acceleration; Methods; Integrated display helmets; Centrifuge test