Sunday, August 28

Night Vision Technology

Night vision devices attached to vehicles there by reduces the chances of accidents both on and off the roads. Many leading car manufacturers have diverted their full R&D towards developing accident prevention technologies rather than going for higher efficiencies or higher torque production.

Electromagnetic Spectrum

Before going into the night vision systems it is necessary to understand something about the electromagnetic spectrum. Humans are visible only to the rays felling under the visible region of electromagnetic spectrum and are invisible to both the infra-red as well as the ultra violet region of the electromagnetic spectrum.

But night vision technology makes it possible for the humans to view the rays felling in the infra-red region of the electromagnetic spectrum, that is generally the night vision systems used in automobiles captures the infra-red image of distant obstacles on road as every object emits infra-red rays (heat rays) even during night. This image is viewed in a screen and the driver can thus apply the brakes as required.

Two Types Of Night Vision Technologies On The Market

Far Infrared (FIR) and Near Infrared (NIR) .FIR detects the radiation which all objects emit, while NIR detects the reflected illumination in a frequency just outside the visible range of a human being. All cars today have an acceptable "night vision" system. That is the high beam headlights of the vehicle. Even though they could be improved theirperformances are at least acceptable. However, in many areas, highbeams are of very limited use due to oncoming traffic. The insufficient night-time visibility originates in the fact that the high beam headlights are rarely possible to use. A Night Vision system must therefore be a system that increases visibility in situations where only low beam headlights can be used today.

Fir And Nir Night Vision Systems

Both NIR and FIR technology offer substantial benefits in different conditions. Both types of systems can also be used together with high beam headlights. The benefit of NIR systems together with high beams may be limited, as NIR systems could be compared with driving using high beams, but without blinding the other road users. The longer range of FIR systems would also make them very effective on dark roads as complements to the high beams of the vehicle. However, as concluded the previous section. Pedestrian detection while facing other vehicles with oncoming headlights should be the main evaluation criteria of a Night Vision system.

The Human-Machine Interface

The population group likely to benefit the most of all from the extra information provided is elderly people due to the degradation in vision this group experience with age (see table 1). However, it has also been shown that this group is less likely to accept, or utilize, the extra information. The Human-Machine Interface (HMI) between the system and the driver is fundamental for successful acceptance, especially among elderly drivers. Proper understanding of the required performance of the system and the expectation of the driver is a prerequisite for designing a good HMI. The primary issue should not be the type of display, but what information to provide to the driver and how it should be done.

A Night Vision System May Operate In Following Modes

Use the system as a look-ahead display to increase the preview — an extended view into the road ahead.

1) Use the system as a look-ahead display combined with a warning that directs the driver's attention to thedisplay when a risk has been identified.

2) Use the system as a look-ahead display but highlighting risky objects like pedestrians.

3) Use the sensor as a data source only and provide a warning when a risk exceeds a given threshold.


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