Three related experiments looked at the effects of a Night Vision Enhancement System (NVES) on driving performance, with differences in image size ratio, lateral position and direct/indirect viewing as parameters. The experiments used experienced drivers in a fixed base virtual-reality driving simulator. Experiment 1 found that subjects using an NVES gained time to assess the situation and choose an appropriate response, which was seen in terms of better control of braking and swerving. Contrary to expectations, subjects did not drive significantly faster when using the NVES. Experiment 2 found that a 1:2 display ratio resulted in better anticipatory control without any adverse effects from differences in recognition distances. When using an NVES display displaced laterally from the normal line of sight, drivers kept the vehicle closer to the middle of the road. They also found the displaced position less favourable than one in the normal line of sight, although there were no strong negative effects of the displacement. Experiment 3 compared a virtual (collimated) display to a direct viewing Flat Panel, with the hypothesis that reduced need of accommodation would lead to smoother driving. The results showed some differences between the two display types, although they were small compared to the effects of learning. Altogether the experiments confirmed that an NVES leads to an indisputable improvement in the drivers' anticipatory control, and hence has considerable safety potential. This work has also emphasised the need to consider the combined effects of an NVES as a system on driving, rather than to do classical controlled experiments.
Abstract