Multiobjective Global Optimization of Space Mission Design using Evolutionary Methods and Interval Analysis
- Paper number
IAC-04-U.3.A.04
- Author
Mr. Pierluigi Di Lizia, Politecnico di Milano, Italy
- Year
2004
- Abstract
Introduction. The purpose of the study was to explore the effects of long-duration space flight on the acquisition of specific visual targets in the horizontal plane. Methods. Seven cosmonauts (4 high performance pilots and 3 non-pilots) who had flown between 186-198 days on Mir served as subjects. Baseline testing was performed four times prior to launch and four times following landing. During testing the subjects were required to acquire targets that were randomly presented at +20, +30 and +60 angular degrees from center with both a head and eye movement using a time optimal strategy. Horizontal eye movements were recorded with EOG and head movements with tri-axial angular rate sensors. Results. Prior to flight two unique head movement strategies, related primarily to piloting experience, were used for target acquisition. Non-pilots employed a Type-I strategy consisting of high velocity head movements with large peak amplitudes, while high performance pilots used primarily low velocity, small amplitude head movements (Type-II) to acquire the targets (p<0.02). For both strategies peak head velocities increased as the angular distance to the target increased (p<0.01) resulting in greater discrimination between strategies for the 60 degrees targets. While preflight eye velocity between strategies did not reach statistical significance, postflight testing revealed a decrease in eye velocity for Type-I compared with their preflight performance (p<0.05) at the 60° targets. Postflight the Type-I group showed a decrease in head velocity (p<0.20) while the Type-II group increased head velocity (p<0.02). Variability on both head and eye parameters tended to increase postflight for both types of strategies. Conclusion. The primary purpose of coordinating head and eye movements for target acquisition is to bring the target onto foveal center in the most efficient manner. Our results are in agreement with the earlier findings of Barmin et al. (1983) on eye-head coordination parameters in pilots and non-pilots. Clearly, pilots have adopted a strategy for coping with changing gravitoinertial forces by restricting high velocity head movements, tending to use the eyes rather than the head within a stable platform (skull). Non-pilots, on the other hand, frequently rely on the head to bring the target within foveal range.
- Abstract document
- Manuscript document
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