Development of Test and Evaluation Methodologies for Headborne Low Light Sensor Systems
Authors: Jose Villa, Edward Hennessy, Blake Mitchell, Reeve Goodenough, Rebecca Skulsky
Abstract: The military is working on improving technical capabilities by developing increasingly advanced low-light sensor headborne systems. There are several known limitations of legacy night vision devices (e.g., narrow field of view, poor depth perception, monochrome display, monocular output), and as technology moves forward, the U.S. Army needs ways to test and evaluate visual performance between systems. The presented research sought to identify, modify and/or develop a series of test methodologies to assess the visual performance of users while wearing these new technologies.Standardized vision performance tests have been used for several decades to assess visual capabilities of the human eye. These tests have been validated through research and clinical usage and are accepted as means of assessing vision, but usually only for the bare eye. Additionally, some tests cannot be used exactly as designed because of one or more design or functional characteristics of night vision/visual enhancement devices (e.g., helmet mounting, monocular view, etc.). We set out to assess the potential of each standard test to be used as designed and, when that was not possible, we modified the test and assessed its potential as a test and evaluation tool for developmental systems.The methodologies were assessed with 14 male, active-duty infantry Soldiers (Age: 22.5±4.31; years in service 3.2±2.40) who all had normal corrected vision (1 participant was red-green color blind). The test included two legacy night vision devices and one prototype device. The test was conducted to both assess the methodologies and compare the legacy devices to the prototype device to determine any improvements in prototype performance over the legacy device performance.Seven tasks were assessed in this study: 1. The Pelli-Robson Contrast Sensitivity test, which showed significant differences between the tested systems. 2. The Howard-Dolman test (depth perception), which did not result in significant differences between the systems. 3. Field of view performance, using a modernized version of a Ferree-Rand projection perimeter, which resulted in significant differences between the tested systems. 4. A timed pegboard task, to assess hand-eye coordination and dexterity performance, which showed significant differences between the tested systems. 5. A visual acuity assessment task, which assesses the vestibulo-ocuar reflex (VOR) function, showed significant differences between the tested systems. 6. A modified version of the Multi-Target Stepping Task, used to assess limb control, showed significant differences between the tested systems. 7. A novel target stamping task developed to evaluate hand-eye coordination and to measure the impacts on reach accuracy, showed significant differences between the tested systems.Initial testing shows these methodologies are promising as tools to evaluate night vision devices. Other than the Howard-Dolman test, all were sensitive enough to statistically differentiate between the tested items. Follow-on steps include: conducting model analysis to understand the relationship between performance in a given task versus the other; develop the assessed methodologies further to improve test reliability; develop and identify other potential new tests and tools to use as evaluation methods; and utilize the finalized methodologies in any applicable system evaluations.
Keywords: headborne systems, night vision systems, test methodologies, system assessment tools, depth perception, field of view, hand, eye coordination
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