In every automobile, the function of the headlight is to illuminate the road ahead of the automobile so as to reveal objects ahead from a safe distance. At the same time, it should cause minimum discomfort for drivers coming from the opposite side. In order to achieve this, a 'meeting' beam (dip beam) is provided in addition to the driving beam (high beam) so as to reduce the dazzle for those approaching head-on to the vehicle. While the present practice is to manually switch between the beams, Raksha Beam Assist(RBA) intends to automatically change the headlight circuit to either high beam or dip beam given a particular set of road conditions, without the intervention of the driver.
A study carried out by Central Road Research Institute, New Delhi, (Road Research Paper No.216), reveals the poor state of affairs on the Indian roads, regarding dipping. The observations and recommendations of the study group on road safety constituted by the Government of India vide Resolution No.19T (14) 68, dated June 3, 1969, is as follows:
A frequent cause of accidents at nights is the glare caused by oncoming vehicles which momentarily blinds the driver's vision. It takes three to eight seconds for a person with good eyesight to recover from the glare and during this time, the vehicle will have covered a long distance in utter darkness and it will be sheer luck if it escapes an accident. A glare recovery test should be carried out to gauge the applicant's ability in this direction, followed by tests pertaining t color and night blindness.
Manual beam shifting is not being done satisfactorily due to a variety of reasons, which includes sheer physical strain involved in operation of the dipper switch hundreds of times every night. (The total switching instances for a single night will be 1000 if we consider 8 hours of traveling and one encounter every one-minute and could exceed this number if one travels on roads with dense traffic).
The other reason includes a general tendency of paying more attention to steering control at the cost of dipping during a critical vehicle meeting situation especially in the case of heavy loaded vehicles. More reasons are the physiological and psychological states of a driver, which are influenced by a variety of factors like working hours, economic issues and social factors etc. Another major cause is 'ego problem', which makes each one wait till the other person initiates dipping, which may not happen.
The human eye, one of the most complex organs and the greatest gift of nature, is equipped with a variety of adaptation abilities. However, it is incapacitated by glare. The human eye's inability to refuse glare sources in the normal visual field (the sun does not fall in the normal visual field) during the long evolution process might be because nature was unaware of man's potential to create disabling sources-the most serious of which is vehicle headlight glare. The visibility of an object is determined by many factors apart from background luminance. Mere reduction of background luminance by an RBA in a particular situation need not necessarily result in clear perception of the objects on the road through visual information.
The physical dimensions of the object, the luminance reaching the object, it's reflectance factor, its color contrast, its time constancy, its movement in space, etc. determine the nature and quantum of visual information available. The actual perception is dependent on the physical condition and the perception method of the viewer. The headlight systems of the vehicle, including the number and type of lamps, their alignment and their efficiency, all play a vital role in influencing the visibility of objects on the road.
If the road is lit, the visibility of the user will be aided by the road lighting and his dependence on the vehicle lighting system will be drastically reduced. Consequently, when the automobile is traveling on a lit road the RBA can maintain the head lamps in dip beam. This functional behavior will also help other road users like cyclists, rickshaws and other non-motorized traffic. RBA is provided with the capability to assess road lighting status. This ability enables the RBA to automatically change its operational in accordance with the road lighting status.