: Geiser, G.; Nirschl, G.

Abstract
A Driver's Warning Assistant(DWA) differs from an automatic co-pilot by only presenting warning messages to the driver,instead of acting upon the vehicle or the environment. It is an open question whether combinations of both types of assistance system are feasible with automatic intervention if the driver has been warned without success, or if there is no chance for a warninq message leading to an appropriate action by the driver in due time. In this case difficult questions of task allocation and of responsibility have to be answered. The evaluation has begun and will continue with DWAs dedicated to special driving tasks, e.g. parking, lane keeping, overtaking, crossing. These DWAs have a competence limited to one of the driver's tasks, so that the driver can only expect support for this single task. In a car equipped with such a specialized DWA the driver has to learn the limits of the DWA's competence. Additionally, the case has to be considered in which a specialized DWA has limit ed competence for its task. This means that the support of a driver by the DWA is limited to a subset of all possible situations (e.g. to situations with good sight conditions). Under certain circumstances (e.g. hidden obstacles) the driver might not be supported. It has to be clarified whether this can be learned and will be accepted by the driver. A crucial topic in the development of a DWA is the timing of warning messages for the driver. The moment of warning on the one hand has to be chosen early enough to enable the driver to react appropriately. This means that the inevitable reaction time, which the driver needs to receive and process the DWA's message and to prepare a reaction, has to be considered. On the other hand the warning message should not be presented too early as this would annoy the driver and result in poor acceptance of the DWA. Therefore, it is important to integrate a time-budget analysis in the development phase and in the run-time version of a DWA, leading to