Flight Investigation of Hyperstereo Vision in Helmet-Mounted Display Designs

A number of image intensification (I2)-based helmet-mounted display (HMD) designs, both past and present, have attempted to overcome center-of-mass (CM) problems by moving the I2 tubes to the sides of the helmet. Such a design approach induces a visual condition referred to as hyperstereo vision (or hyperstereopsis). This condition manifests itself to the user as an exaggerated sense of depth perception, causing near- to mid-range objects to appear closer than they really are. Hyperstereopsis is potentially a major concern for helicopter operations that are conducted at low altitudes. A limited flight study was conducted to identify which flight maneuvers present the greatest difficulty to helicopter aviators and hence require additional study of their impact on flight performance and safety. In this exploratory study, two aviators experienced a total of eight hours and three aviators a single hour of flight as a non-flying pilot wearing a hyperstereo HMD. The pilot on the controls conducted a series if 13 maneuvers deemed to be typically and routinely performed by U.S. Army aviators. The maneuvers of roll-on and sloping terrain landings were identified as the most problematic when using the hyperstereo HMD. Subjects reported a 5-8 hour “adaptation” period for the remaining maneuvers.