We recently completed a small study of highly reclined passenger postures. Many conceptual designs for future automated vehicles anticipate that passengers will want to recline for relaxation or even sleep. Although nearly all front passenger seats currently recline, the seats are not designed for comfort and support in highly reclined postures. (I define highly reclined postures as those for which head support is needed for comfort. This typically starts at about 30 degrees from vertical for most seats and sitters.) Moreover,current vehicles are not designed to provide crash protection in highly reclined postures.
In what we believe to be the first study of its kind, we measured posture and belt fit for 24 men and women with a wide range of body size as they sat in a typical front passenger seat with back angles of 23, 33, 43, and 53 degrees (referenced to SAE A40 measured at 23 degrees). Postures were measured with and without sitter-selected head support. The results were analyzed to develop posture-prediction models for use in safety assessments using computational human models.
