Repeatability, Reproducibility, and Validity of a New Method for Characterizing Lumbar Support in Automotive Seating.

Objective: This article describes a new and more repeatable, reproducible, and valid test method for characterizing lumbar support in automotive seating. Background: Lumbar support is important because it affects occupant accommodation and perceptions of seat comfort. Assessing only the lumbar mechanism-particularly in terms of travel-is inadequate because it does not consider the effects of trim and foam. Method: The Society of Automotive Engineers' next-generation H-Point machine and associated loading protocol were used as the basis for the new test. Results: The method was found to satisfy minimum gage repeatability and reproducibility requirements. Validity was demonstrated through a regression model that revealed 93.9% of the variance in subjective ratings of poor uncomfortable lumbar support can be explained by two objective indicators: (1) lumbar support prominence in the full-off position and (2) effective travel. Conclusion: The method can be used to differentiate between seats offering two-way adjustable lumbar support. The best two-way adjustable lumbar seat systems are those that couple little to no lumbar support in the starting or off position (i.e., they are nonintrusive) with a considerable amount of effective or perceptible travel. Application: The automotive industry has long needed a way to address the fact that consumers want more lumbar support than their seats currently supply. This contribution offers a method to objectify an important aspect of automotive seating comfort-namely, lumbar support. This should help human factors professionals produce, but not necessarily guarantee, better consumer ratings. [ABSTRACT FROM AUTHOR]