Publication

Occupants have already in today’s cars the opportunity to choose various reclined seatingpositions. As highly automated driving (HAD) vehicles are introduced on the market, thepossibility to sit in reclined positions will increase. The car manufacturers will most likely beresponsible for ensuring crash safety for new seating positions. Therefore, the restraint systemhas to be developed to make these seating positions safe.
The objective of this master thesis is to make reclined seating positions safer and comfortablein level 4 HAD vehicles, with a focus on the lap belt geometry and submarining. The aim isto investigate how people want to sit in relaxed positions in level 4 HAD vehicles. With thatinformation provided, develop a restraint system that meets the user and safety requirementswith a focus on submarining. Submarining is an unwanted phenomenon that can occur duringfrontal collisions where the occupant slides under the lap belt (Hermitte & Labrousse, 2012).
The solution should be delivered as sketches and renderings. The work is performed incooperation with Autoliv Development AB. The project has been conducted by using a usercentered-design process. The methods have been chosen to generate user-centered results.Autoliv, as the constituent, has been involved in the project through all of the project’s phases, which has been benefiting for the progress.
The result shows that in today’s cars, 48% of the passengers preferred to sit in a relaxed positionwhere the seat back was reclined over 30 degrees. 56% of the passengers chose a seat backangle over 30 degrees when they wished to sleep. In the level 4 HAD vehicles, people wanted torecline the seat back more. 80% chose a seat back angle over 30 degrees when relaxing, in boththe drive’s and passenger seat. 100% of the passengers chose a seat back angle over 30 degreeswhen they wished to sleep.
The result indicates that the lap belt geometry deteriorated when the seat back reached anangle over 30 degrees. This means that the majority would, in their relaxed position, have alap belt geometry that could increase the risk for submarining. The pelvis rotation that comeswith reclined positions is one of the reasons that cause submarining (Couturier, Faure, Satué& Huguet, 2007). SafeX is a concept of a restraint system, developed as a part of this thesis. Itprovides a safer way for the occupants to sit in their most comfortable seating positions, withthe pelvis rotation in consideration.
This project provides Autoliv with valuable data for further investigation and development ofrestraint systems.