Ergonomics Studies on Non-Traditional In-Vehicle Displays for Reducing Information Access Costs
Ergonomics Studies on Non-Traditional In-Vehicle Displays for Reducing Information Access Costs Donghyun Beck Department of Industrial Engineering The Graduate School Seoul National University Drivers should keep their eyes forward most of the time during driving to be in full control of the vehicle and to be aware of the dynamic road scene. Thus, it is important to locate in-vehicle displays showing information required for a series of driving tasks close to the driver’s forward line-of-sight, and therefore, to reduce the eyes-off-the-road time. Automotive head-up display (HUD) system and camera monitor system (CMS) are promising non-traditional in-vehicle display systems that can reduce information access costs. HUD presents various information items directly on the driver’s forward field of view, and allows the drivers to acquire necessary information while looking at the road ahead. CMS consists of cameras capturing vehicle’s side and rear views and in-vehicle electronic displays presenting the real-time visual information, allowing the driver to obtain it inside a vehicle. Despite the potential benefits and promising applications of HUD system and CMS, however, there are some important research questions to be addressed for their ergonomics design. As for HUD system, presenting many information items indiscriminately can cause undesirable consequences, such as information overload, visual clutter and cognitive capture. Thus, only the necessary and important information must be selected and adequately presented according to the driving situation at hand. As for CMS, the electronic displays can be placed at any positions inside a vehicle and this flexibility in display layout design may be leveraged to develop systems that facilitate the driver’s information processing, and also, alleviate the physical demands associated with checking side and rear views. Therefore, the following ergonomics research questions were considered: 1) ‘Among various information items displayed by the existing HUD systems, which ones are important?’, 2) ‘How should the important HUD information items be presented according to the driving situation?', 3) ‘What are the design characteristics of CMS display layouts that can facilitate driver information processing?’, and 4) ‘What are the design characteristics of CMS display layouts that can reduce physical demands of driving?’ As an effort to address some key knowledge gaps regarding these research questions and contribute to the ergonomics design of these non-traditional in-vehicle display systems, two major studies were conducted – one on HUD information items, and the other on CMS display layouts. In the study on HUD information items, a user survey was conducted to 1) determine the perceived importance of twenty-two information items displayed by the existing commercial automotive HUD systems, and to 2) examine the contexts of use and the user-perceived design improvement points for high-priority HUD information items. A total of fifty-one drivers with significant prior HUD use experience participated. For each information item, the participants subjectively evaluated its importance, and described its contexts of use and design improvement points. The information items varied greatly in perceived importance, and current speed, speed limit, turn-by-turn navigation instructions, maintenance warning, cruise control status, and low fuel warning were of highest importance. For eleven high-priority information items, design implications and future research directions for the ergonomics design of HUD systems were derived. In the study on CMS display layouts, a driving simulator experiment was conducted to comparatively evaluate three CMS display layouts with the traditional side-view mirror arrangement in terms of 1) driver information processing and 2) physical demands of driving. The three layouts placed two side-view displays inside the car nearby the conventional side-view mirrors, on the dashboard at each side of the steering wheel, and on the center fascia with the displays joined side-by-side, respectively. Twenty-two participants performed a safety-critical lane changing task with each layout design. Compared to the traditional mirror system, all three CMS display layouts facilitated information processing and reduced physical demands. Design characteristics leading to such beneficial effects were placing CMS displays close to the normal line-of-sight to reduce eye gaze travel distance and locating each CMS display on each side of the driver to maintain compatibility. Keywords: head up display (HUD), experienced users, importance of information items, contexts of information use, design improvement points, camera monitor system (CMS), in-vehicle side-view displays, display layout, information processing, physical demands Student Number: 2013-21072
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High Cognitive Load Assessment in Drivers Through Wireless Electroencephalography and the Validation of a Modified
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Investigating driver gaze behavior during lane changes using two visual cues: ambient light and focal icons
Currently, lane change decision aid systems primarily address foveal vision and thus compete for drivers’ attention with interfaces of other assistant systems. Also, alternative modalities such as acoustic perception (Mahapatra et al., 2008), tactile perception (Löcken et al., 2015), or peripheral vision (Löcken et al., 2015), have been introduced for lane change support. We are especially interested in ambient light displays (ALD) addressing peripheral vision since they can adapt to the driver’s attention using changing saliency levels (Matthews et al., 2004). The primary objective of this research is to compare the effect of ambient light and focal icons on driving performance and gaze behavior. We conducted two driving simulator experiments. The first experiment evaluated an ambient light cue in a free driving scenario. The second one focused on the difference in gaze behavior between ALD and focal icons, called “abstract faces with emotional expressions” (FEE). The results show that drivers decide more often for safe gaps in rightward maneuvers with ambient light cues. Similarly, drivers decide to overtake more often when the gaps are big enough with both displays in the second experiment. Regarding gaze behavior, drivers looked longer towards the forward area, and less often and shorter into the side mirrors when using ALD. This effect supports the assumption that drivers perceive the ALD with peripheral vision. In contrast, FEE did not significantly affect the gaze behavior when compared to driving without assistance. These results help us to understand the effect of different modalities on performance and gaze behavior, and to explore appropriate modalities for lane change support.
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The influence of a gaze direction based attention request to maintain mode awareness
Future vehicles will combine different levels of driving automation characterized by varying responsibilities for users. This development will intensify system complexity which poses the risk of confusing the driver. We hypothesize that the users’ mode awareness suffers especially when changing from Level 3 “Conditional Automation” to Level 2 “Partial Automation”. Therefore, automated systems need to be designed in a way that minimizes confusion with regard to the automation mode. The article describes the influence of a gaze direction based Attention Request (ATR) to avoid mode confusion with the aim of contributing to the reliable operation of different levels of automation in one vehicle. Two similar studies were conducted. One took place in a dynamic driving simulator with 40 participants. Every participant drove for 10 minutes with a partially automated driving (PAD) (SAE level 2) system and conditionally automated driving (CAD) (SAE level 3) system in the order PAD/CAD/PAD. The second study was conducted on a German highway in a Wizard-of-Oz car. All 40 test persons drove in each PAD and CAD phase 8 minutes in the order of PAD/CAD/PAD/CAD/PAD/CAD. The CAD-system was in both studies a high performing Hands-Off Level 2 system that required no input of the driver. To promote the same mental model for all participants as it is a requirement to measure the differences in mode awareness, all persons became a detailed description of the Level 2 and 3 systems presented by video and text. Both studies used a between-subject-design to measure the influence of an ATR. The ATR was based on the gaze direction of the driver and initiated by the investigator when the drivers gaze was not in the street AOI for longer than 4 seconds. Mode awareness was operationalized by the visual attention towards driving-relevant areas, a qualitative analysis of a questionnaire and followed by an interview. The ATR was proven to be an effective action to maintain the mode awareness by using a level 2 and 3 system within one car. Specifically, the visual attention did not decrease by an intermitted CAD drive during PAD. Moreover, the visual attention to the road scene increased for the group with an ATR during PAD. This was indicated by the measurement of a significant interaction effect for the development of the visual attention to the road scene for the groups with and without ATR. Thus, the gaze direction-based ATR was proven to be an effective measure to maintain mode awareness, if different levels of automation are combined in one vehicle. This result helps to take the next step for realizing such combined multilevel systems with tailored HMIs for advanced driver assistance systems. Moreover, it has to be considered, that the studies put the emphasis on the first glance of the drivers, during their first contact with partly and conditionally automated systems. Further studies should investigate the long term effect of an ATR.
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Trust in highly automated driving
The automotive industry is on the verge of a new technology: self-driving vehicles. Such highly automated driving vehicles are more and more technically feasible, and corporations and research institutes all over the world are investing time and money to bring the once futuristic vision on the road. The technology is developed with the goal to release the driver from the manual task of controlling the vehicle. Through that, it shall increase driving comfort and, above all, contribute to the enhancement of overall road safety. Beyond further technical development, psychological aspects and the creation of an optimal user experience gain importance for highly automated driving functionality. In particular, trust in this kind of functionality has yet to be built up for future societal usage. Otherwise, if people are not willing to entrust control to such a vehicle, it will not be used and the potential of highly automated driving cannot be fully exploited. The aim of this work is to identify influential factors on trust in highly automated driving vehicles and to examine how this trust can be supported by a specific human-machine interface (HMI). To this end, three main studies were conducted with participants. Different HMI concepts were tested in these user studies in a prototype vehicle on public roads as well as in a simulated environment. The aim of the first real-driving study (N = 28) with the highly automated driving vehicle was to test influential factors on trust in such a vehicle. The personality characteristic desire for control as well as a general attitude towards technology were identified as relevant factors. However, most important for trust was the perceived performance of the system. In the second user study (N = 72), the influence of system boundaries on trust was examined with the help of a simulated environment. It was proven that the type of the experienced system limit plays a crucial role. In particular, the non-detection of a relevant event within the driving situation diminished trust, while a false detection led to little trust reduction. Over several trial days, it was examined in a third user study (N = 18) how trust develops beyond a first contact with a highly automated driving system. In this real-driving study, first indications were found that the relevance of the HMI increases with prolonged system use. A trust model set up based on previous insights and theories was transferred to the new context of highly automated driving with the help of these studies. Furthermore, guidelines for the design of an HMI concept for highly automated vehicles were collected and applied. Thereby, the insights of this work support developers in designing HMI concepts to promote trust in automated driving functionality. Even if the future driver no longer needs to take over driving tasks, it is recommended to provide an adequate HMI concept supporting trust development.
