Motor vehicles generally use headlamps to illuminate the road during low visibility conditions. In the past, vehicle generally employed two headlamps, one on either side, mounted at the front of the vehicle. Recent years have seen a proliferation of multiple headlamp systems, however, and many vehicles now feature at least two headlamps on each side. Each headlamp, or each pair of headlamps, offers two illumination conditions, referred to as high beam and low beam. The high beam setting offers maximum illumination, as the beams are aimed generally straight ahead of the vehicle. If oncoming traffic is present, however, high beams will impair the visibility of approaching drivers, and therefore a low beam setting is available, in which the headlight beams are directed relatively downward. Most countries, including the United States, ensure safety through regulations specifying the light patterns produced by mounted headlamps. In general, a vehicle under test is positioned in a stated position relative to a test surface, the headlamps are illuminated, and the resulting light pattern is analyzed. Headlamp mounting arrangements include an aiming adjustment mechanism, which typically shifts the orientation of the headlamp beam on horizontal and vertical axes, and that mechanism is used to aim the beams as required. A target or pattern on the projecting surface assists the aiming process, also referred to as aiming the headlamps.
Headlamps are initially aimed during manufacture, and that process must occur smoothly and rapidly. Typically, the vehicle assembly line includes a headlamp aiming station where that task is performed. It can be readily understood that headlamp aiming criteria vary with vehicle height, width, and other factors related to vehicle make, model, and build. Manufacturers have attempted to streamline the headlamp aiming process by identifying individual automobiles with a given build specification. In practice, these measures have not been noticeably successful, as it has been found that even small variations, particularly in height, have cause significant variation in results, causing undesirable cost and effort. A need therefore remains for headlamp aiming equipment and processes that allow flexible aiming over a range of vehicle types.