The use of haptics when interacting with in-car interfaces
Abstract: Humans use all their senses when they explore and interact with the environment. In human-machine interaction, vision is the dominant sense and interfaces are seldom designed to provide haptic information, i.e. information that can be gathered by touch. There is a trend among car manufacturers to merge functions into multifunctional interfaces. These interfaces are generally based on one display and one main interaction device and have been criticized for being visually demanding to use while driving. To facilitate interaction with such an interface it is possible to utilize an interaction device, e.g. a rotary control, that can provide varying haptic information. The main purpose of this thesis was to investigate in-car human-machine interaction, with a primary focus on the use of haptics. Four experimental studies are included in the thesis. In study I the participants focused on the interaction with the experimental interface. In studies II, III and IV the interaction with the experimental interfaces was carried out while concurrently driving a car simulator. Study I demonstrated that congruent haptic and visual interface information can be transferred between the sensory modalities, but the transfer from haptics to vision seemed to be easier than from vision to haptics. Study II showed that, even though the eyes were kept on the road when only haptic interface information was provided, driving performance deteriorated. In studies I and II haptic interaction required serial processing of information which seemed to be trying. As a consequence the participants relied more on visual interface information when it was available. Study III demonstrated that well designed assisting haptics can facilitate interaction with a multifunctional interface. However, the study also indicated that it is important to carefully assess the use of the haptics since poorly designed haptics may confuse the user. Study IV compared an interface manoeuvred by a rotary control and a touch screen interface. The study showed that the optimal interface is dependent on the task being performed. However, it was shown that driving performance was affected to a greater extent when the touch screen interface was used, probably as a cause of the lower display position.
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