Driving Behavior and Simulator Sickness While Driving the Vehicle in the Loop: Validation of Longitudinal Driving Behavior

The Vehicle in the Loop (VIL) is a simulator, which combines real driving experience with the replicability and safety of simulators. In the VIL test setup a real test vehicle is combined with a virtual testing environment which is displayed to the user via a head-mounted display (HMD). In theory, this simulation concept renders the VIL uniquely suited to the development and evaluation of numerous automotive applications, including driver assistance systems. Aiming to assess the extent to which the VIL elicits realistic driving responses, a validation study was performed. In this first validation study the focus was on longitudinal driving behavior. 44 participants performed five common traffic maneuvers in reality and the VIL setup. Simulator sickness was assessed with the simulator sickness questionnaire (SSQ). Descriptive and inferential analyses of the data showed that the VIL achieves relative validity concerning brake pressure and reaction times and absolute validity concerning the steering angle. However, subjects showed longer reaction times and accelerated more smoothly while driving the VIL. One possible explanation for these results could be the presence of simulator sickness. Overall, the study indicates that the VIL represents a suitable testing method for the evaluation and development of driver assistance systems. The study also provided clear indications for the future development of the VIL.