Raphael Zenk

The effect of a lightweight massage system in a car seat on comfort and electromyogram.

OBJECTIVE The objective of this study was to determine the effect of a lightweight low-intensity massage system (LWMAS) in a car seat on the electromyogram (EMG) of the neck and shoulder muscles and on the comfort experience during driving. METHODS Two experiments were performed during driving with and without the active LWMAS in the seat. Subjective measurements were taken, in which the comfort experience was recorded for 20 participants driving a prescribed path around Munich for 120 minutes. Then objective (surface EMG above the rhomboideus and trapezius muscles) measurements and subjective measurements of the comfort experience were recorded over 7 laps on a test track for 24 participants. RESULTS The comfort was higher, and the EMG was significantly lower in the trapezius area while driving with the LWMAS. CONCLUSION Despite the fact that the LWMAS system is lightweight, has low intensity, and might have had a smaller effect, similar effects to previous studies with heavier systems were found, indicating that this massage system increases comfort and reduces muscle activity during driving as well.

Predicting Overall Seating Discomfort Based on Body Area Ratings

For car manufacturers, seating comfort is becoming more and more important in distinguishing themselves from their competitors. There is a simultaneous demand for shorter development times and more comfortable seats. Comfort in automobile seats is a multi-dimensional and complex problem. Many current sophisticated measuring tools were consulted, but it is unclear on which factors one should concentrate attention when measuring comfort. The goal of this paper is to find a model in order to predict the overall seating discomfort based on body area ratings. Besides micro climate, the pressure distribution appears to be the most objective measure comprising with the clearest association with the subjective ratings. Therefore an analysis with three different test series was designed, allowing the variation of pressure on the seat surface. In parallel the subjects were asked to judge the local and the overall sensation. During the experiment the pressure distribution between test subject and seat was gathered by a pressure mat. The test series are based on 84 subjects and over 500 measuring results, which include three different settings for seat cushion and backrest.