ware components. The second section discusses some of the authors' experiences with the IDS.
Driving is one of the most complex tasks with which the majority of the population is familiar. Despite its commonality, driving is a rather complex task that involves quick decision making, significant motor skills, and the ability to quickly process information from a variety of sources. To simulate this task faithfully in a simulator requires extensive realism and fidelity with respect to several factors, including the hardware providing vibration, sound, and visual stimuli involved in driving a vehicle, the performance characteristics associated with the vehicle, and the external virtual environment in which a simulation takes place. In addition to simply reproducing these cues for the driver of the simulator, several other requirements are necessary for a simulator used to conduct scientific research. These requirements include an external environment that can be customized to meet study requirements; a realistic yet repeatable set of behaviors of the surrounding area; extensive data collection and analysis capabilities; and from an engineering standpoint, strict determinism and repeatability in the execution of the overall system.
The IDS (Freeman et al., 1995; Kuhl et al., 1995) is a high-fidelity driving simulator located at the University of Iowa's Center for Computer-Aided Design. The IDS cueing subsystems utilize state-of-the-art technology to provide visual, motion, audio, and tactile-instrument feedback. In addition, the IDS uses a sophisticated scenario control system (Cremer et al., 1994), which includes independent simulations of multiple robot drivers that comprise the external traffic participants. The wide range of uses that has been required of IDS imposes some surprisingly challenging technical requirements. Very often, it is not only necessary to model the environment faithfully, but the environment must be modeled differently from actual life in order to test some hypotheses. For example, in order to test a new highway design, the visual database must be constructed to reflect not traditional design rules but the new rules that are under study. To test and evaluate new in-vehicle devices requires the IDS to simulate systems that are not in existence, a task perfectly fit for a simulation that is nevertheless challenging, given the lack of engineering experience in the operation of the new devices. Similarly, to research reaction to specific traffic situations, the IDS must be able to reproduce traffic scenarios faithfully that may involve multiple other robot drivers coordinated to produce interactions (such as lane incursions and sudden braking), which may or may not be able to be reproduced in real life. To achieve this level of programmability and reconfigurability, the IDS utilizes several advanced technologies associated with its cueing systems. Requirements on these systems, along with details on their design, are given below.