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A method for communication linking the vehicle user and the lighting engineer has been developed to improve the headlight beam pattern development process. A technique called the semantic differential has been used to quantify the user's perception on a large number of attributes of the beam pattern. The basis of the technique utilizes descriptive words used by both drivers and engineers to characterize headlight beam patterns. Beam pattern evaluations conducted in a series of dynamic drive situations formed the initial data base. Subsequent evaluations using this technique have facilitated close and quick interaction between the customer and the engineer during the development of headlight beam patterns.

The method of communication between the customer and the engineer has been refined to further improve the headlight beam pattern development process. The refinements included: a) reduction of word pairs used for semantic differential scaling and b) use of shortened questionnaire on night-roadway viewing zones. The added benefit of the new questionnaire method allows the engineer to evaluate the customer responses of the beam pattern within specific areas on the road scene. A statistical technique called factor analysis has been used to evaluate and to reduce the large number of semantic differential word pairs used in the previous work by Jack, O'Day and Bhise (1). A comparison of the two questionnaire forms used in the evaluation surveys was completed based on an evaluation of beam patterns in a dynamic drive situation.

The headlamp beam pattern development process contains both subjective and objective evaluations. The subjective evaluation, communication between the customer and the engineer, was developed in previous work [1][2]. This paper presents exploratory models used in the identification of objective photometric variables of a beam pattern that relate to the subjective impression of the beam pattern. Additional research will allow use of the photometric variables and their selected ranges for designing and evaluating beam patterns to achieve improved customer pleasing beam pattern driving experiences.

Two field studies were conducted on public roads to measure driver head movements while using the left outside passenger car mirror. The first study measured the effects of mirror width in the presence or absence of overtaking traffic. Driver head movements during left lane-changing maneuvers were recorded from a lead vehicle equipped with a motion picture camera and a telephoto-zoom lens. Results showed that, in addition to the head turning motions, the drivers made on the average about 2.0 inches of lateral head movements while using one of the four left outside mirror sizes which ranged in width from 2.3 to 10.6 inches. The drivers were also found to make larger lateral head movements when no other vehicles were present in the mirror as compared to when an overtaking vehicle was present. The second study was conducted in no overtaking traffic with one mirror width and used an improved photographic technique.