Surface contamination, or soiling, of the exterior of road vehicles can be unsightly, can reduce visibility and customer satisfaction, and, with the increasing application of surface-mounted sensors, can degrade the performance of advanced driver-assistance systems. Experimental methods of evaluating surface contamination are increasingly used in the product development process, but the results are generally subjective. The use of computational methods for predicting contamination makes objective measures possible, but comparable data from experiment is an important validation requirement.
This article describes the development of an objective measure of surface contamination arising during experiments. A series of controlled experiments using ultraviolet (UV) dye-doped water are conducted to develop a robust methodology. This process is then applied to a simplified contamination test. An image of a surface, illuminated by an UV lamp, is captured after every test along with a calibration vessel with known fluid depth. The image is processed to remove the influence of variation in incident illumination. The total mass of contamination deposited is then calculated using the calibration vessel to provide the required local fluid depths. The article includes validation of the technique.
