Performance Model for EVA Helmet Mounted Camera and Light Systems

During certain Extra-Vehicular Activity (EVA), a suited crewmember can be used as an extra set of eyes for EVA operations, particularly for robotics. However, for night operations it is sometimes unclear as to the level of performance, such as maximum distance for viewing and the field of view, of the camera and light system mounted on the EVA helmet for direct and indirect viewing. To determine this performance, empirical data and computer modeling was used to compute the viewing envelopes for various configurations possible such as the use of floodlights and spotlights. Using measurements of the individual lights, a computer model was used to predict the light’s performance when used in pairs for two configurations, both pointing straight ahead and focused at 10 feet. The predicted iso-candle measurements were then computed from the model’s output. The various computed envelopes were then compared to determine the configuration with the maximum coverage and minimum contrast across the field of view. The envelopes take into consideration camera performance and direct viewing at a variety of distances and fields of view. The envelopes also provide the illumination levels over time, as battery power diminishes. In addition to assisting robotics operations, these envelopes can be used in the design of EVA worksites or any last minute EVA operation that might require extended collaborative activity between an EVA person and an Intra-Vehicular Activity (IVA) or ground based assistant. The envelopes can also be useful for analyses of luminance issues, such as glare, contrast and low illumination for specific worksites. Finally, this modeling approach permits easy “what if” iterations for the design of camera and illumination systems for EVA suits of the future.