Abstract
Keywords - Rapid Prototyping, Wizard of Oz, Driver Assistance Systems, Human- Machine-Interaction, Human-Machine Interface
Up to now, the resulting restrictions for HMI development from the limited availability of technical components lead to a method where a technological setup is avoided: In the Wizard of Oz Technique a human being takes over the role of the technical system components and simulates complex processes, e.g. the recognition and interpretation of speech inputs. In this field, this method was widespread in the 1990s, when computing power limited speech processing. Wizard of Oz experiments provide a possibility for user testing of future technologies which are not yet available in hardware. For automotive issues, first adaptations into virtual reality environments and driving simulators already exist.
This paper describes the transfer of this experimental technique into a driving vehicle: For research and development of driver assistance systems a Wizard of Oz vehicle was developed. In this vehicle, a hidden second driver in the load compartment is able to take over parts of the driving task varying the degree of automation from manual control to complete automatic control. Besides alternative control of the driving subtasks a cooperative control of the vehicle is possible by simultaneous manipulation of driver and wizard. This setup allows the person on the driver´s seat to experience not yet existing future driver assistance systems. Hence, sensor development issues are no longer limiting user testing and different degrees of "intelligence" of the driver assistance system can be realized before spending effort in technical development. Results from user testing can be generated much earlier in the development process and find their entry into the ongoing system design.
Besides the advantages for early usability testing, this instrument offers outstanding possibilities in the development of assistance functionalities as even very early ideas can be experienced in a real car. Therefore, the Wizard of Oz vehicle is an important instrument within a rapid prototyping approach in the development of assistance systems, completing established development tools such as driving simulators and prototype vehicles.
By means of the description of the technical realization of the experimental vehicle the conception and design of user studies is presented. Here, two example studies designed for validation of the tool are introduced and described: First, an in-vehicle information system was simulated. The system evaluation of 18 users was compared to the evaluation of a real system setup. In the second experiment a lanekeeping system is emulated as an example for intervening driver assistance. 19 users evaluated both the Wizard of Oz system and a prototype lanekeeping system. The results provide the background for a discussion of the advantages and constraints of using the Wizard of Oz-technique in a vehicle for designing HMIs of future driver assistance.