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Interpretation and Optimization of an Adaptive Restraint System With Special Consideration for "Out-of-Position" Situations
Published December 04, 2000 by Fraunhofer Institut Chemische Technologie in Germany
Event: Airbag 2000
As early as the November '96 "Airbag 2000 Symposium" different speakers had already presented information about the problems associated with restraint systems. The injury risk factors from out-of-position children and adults were clearly identified, and potential solutions were presented. These solutions centered mainly on multi-level output inflators, that could support "smart restraint solutions." In addition the different control parameters and load cases were defined. A crash specialist from the medical profession recommends that safety system deployment characteristics should be based upon crash severity and its direction. It was further stated that the system should be "tunable" to account for occupant size as well as position within the vehicle compartment. A list of potential sensor systems and actuators (seatbelts/airbags/pre-tensioner/load-limiter) were also presented at this time.
It can be seen that an increase in system requirements will force larger expenditures for system development. The question is how to optimize the system development to minimize testing and ultimately costs. Numerical simulation is one such possibility that has the potential to reduce these development costs.
In looking at the hardware, the question is: "Which sensors and safety components, when combined, make the best safety system." In other words which system will reduce occupant injuries and yield the most benefit. This decision must be computed together with the overall system expenditures, as no one wants to develop and install a system that does not yield additional benefit. From a sensor point of view we must concern ourselves not only with which information is relevant, but also how reliable are the sensors themselves. Each sensor system has the potential for failure, and we must be aware of the consequences associated with this possibility.
The objective of this study was to develop potential solutions for better defining and optimizing a restraint system. This was based on an understanding of the interactions between the different subsystems, and ultimately defining a system strategies. The job was undertaken by a multi-firm workgroup where each partner contributed their respective strength to the project. Breed Technology was chosen to be responsible for the airbag technology because of there strength in design, production and module optimization. Siemens Restraint Systems was brought in for their expertise in numerical simulation and development methods. Finally, Opel was responsible for the overall system development and integration, based on a current vehicle platform.