Enhancing user experience and safety in the context of automated driving through uncertainty communication

Operators of highly automated driving systems may exhibit behaviour characteristic of overtrust issues due to an insufficient awareness of automation fallibility. Consequently, situation awareness in critical situations is reduced and safe driving performance following emergency takeovers is impeded. Previous research has indicated that conveying system uncertainties may alleviate these issues. However, existing approaches require drivers to attend the uncertainty information with focal attention, likely resulting in missed changes when engaged in non-driving-related tasks. This research project expands on existing work regarding uncertainty communication in the context of automated driving. Specifically, it aims to investigate the implications of conveying uncertainties under consideration of non-driving-related tasks and, based on the outcomes, develop and evaluate an uncertainty display that enhances both user experience and driving safety. In a first step, the impact of visually conveying uncertainties was investigated under consideration of workload, trust, monitoring behaviour, non-driving-related tasks, takeover performance, and situation awareness. For this, an anthropomorphic visual uncertainty display located in the instrument cluster was developed. While the hypothesised benefits for trust calibration and situation awareness were confirmed, the results indicate that visually conveying uncertainties leads to an increased perceived effort due to a higher frequency of monitoring glances. Building on these findings, peripheral awareness displays were explored as a means for conveying uncertainties without the need for focused attention to reduce monitoring glances. As a prerequisite for developing such a display, a systematic literature review was conducted to identify evaluation methods and criteria, which were then coerced into a comprehensive framework. Grounded in this framework, a peripheral awareness display for uncertainty communication was developed and subsequently compared with the initially proposed visual anthropomorphic uncertainty display in a driving simulator study. Eye tracking and subjective workload data indicate that the peripheral awareness display reduces the monitoring effort relative to the visual display, while driving performance and trust data highlight that the benefits of uncertainty communication are maintained. Further, this research project addresses the implications of increasing the functional detail of uncertainty information. Results of a driving simulator study indicate that particularly workload should be considered when increasing the functional detail of uncertainty information. Expanding upon this approach, an augmented reality display concept was developed and a set of visual variables was explored in a forced choice sorting task to assess their ordinal characteristics. Particularly changes in colour hue and animation-based variables received high preference ratings and were ordered consistently from low to high uncertainty. This research project has contributed a series of novel insights and ideas to the field of human factors in automated driving. It confirmed that conveying uncertainties improves trust calibration and situation awareness, but highlighted that using a visual display lessens the positive effects. Addressing this shortcoming, a peripheral awareness display was designed applying a dedicated evaluation framework. Compared with the previously employed visual display, it decreased monitoring glances and, consequentially, perceived effort. Further, an augmented reality-based uncertainty display concept was developed to minimise the workload increments associated with increases in the functional detail of uncertainty information.</div

Automation transparency: Implications of uncertainty communication for human-automation interaction and interfaces

Operators of highly automated driving systems may exhibit behaviour characteristic for overtrust issues due to an insufficient awareness of automation fallibility. Consequently, situation awareness in critical situations is reduced and safe driving performance following emergency takeovers is impeded. A driving simulator study was used to assess the impact of dynamically communicating system uncertainties on monitoring, trust, workload, takeovers, and physiological responses. The uncertainty information was conveyed visually using a stylised heart beat combined with a numerical display and users were engaged in a visual search task. Multilevel analysis results suggest that uncertainty communication helps operators calibrate their trust and gain situation awareness prior to critical situations, resulting in safer takeovers. Additionally, eye tracking data indicate that operators can adjust their gaze behaviour in correspondence with the level of uncertainty. However, conveying uncertainties using a visual display significantly increases operator workload and impedes users in the execution of non-driving related tasks

Enhancing driving safety and user experience through unobtrusive and function-specific feedback

Inappropriate trust in the capabilities of automated driving systems can result in misuse and insufficient monitoring behaviour that impedes safe manual driving performance following takeovers. Previous studies indicate that the communication of system uncertainty can promote appropriate use and monitoring by calibrating trust. However, existing approaches require the driver to regularly glance at the instrument cluster to perceive the changes in uncertainty. This may lead to missed uncertainty changes and user disruptions. Furthermore, the benefits of conveying the uncertainty of the different vehicle functions such as lateral and longitudinal control have yet to be explored. This research addresses these gaps by investigating the impact of unobtrusive and function-specific feedback on driving safety and user experience. Transferring knowledge from other disciplines, several different techniques will be assessed in terms of their suitability for conveying uncertainty in a driving context

Augmented reality displays for communicating uncertainty information in automated driving

Safe manual driving performance following takeovers in conditionally automated driving systems is impeded by a lack in situation awareness, partly due to an inappropriate trust in the system’s capabilities. Previous work has indicated that the communication of system uncertainties can aid the trust calibration process. However, it has yet to be investigated how the information is best conveyed to the human operator. The study outlined in this publication presents an interface layout to visualise function-specific uncertainty information in an augmented reality display and explores the suitability of 11 visual variables. 46 participants completed a sorting task and indicated their preference for each of these variables. The results demonstrate that particularly colour-based and animation-based variables, above all hue, convey a clear order in terms of urgency and are well-received by participants. The presented findings have implications for all augmented reality displays that are intended to show content varying in urgency

Preliminary evaluation of variables for communicating uncertainties using a Haptic seat

Recent findings have indicated that the communication of uncertainties is a promising approach for overcoming human factors challenges associated with overtrust issues. The existing approaches, however, are limited in that they require operators to monitor the instrument cluster to perceive changes. As a consequence, significant changes may be missed and operators are regularly interrupted in the execution of non-driving related tasks even if the system is performing well. To overcome this, unobtrusive interfaces are required that are only interruptive if needed. This paper presents a lab-based study aiming at the preliminary evaluation of haptic variables for communicating automation uncertainties using a haptic vehicle seat. The initial results indicate that particularly increases in amplitude as well as a rhythm consisting of long vibrations separated by short breaks are well suited for communicating the exceedance of specified uncertainty thresholds. The communication of decreases in uncertainty using vibration cannot be recommended