User expectations of partial driving automation capabilities and their effect on information design preferences in the vehicle

Partially automated vehicles present interface design challenges in ensuring the driver remains alert should the vehicle need to hand back control at short notice, but without exposing the driver to cognitive overload. To date, little is known about driver expectations of partial driving automation and whether this affects the information they require inside the vehicle. Twenty-five participants were presented with five partially automated driving events in a driving simulator. After each event, a semi-structured interview was conducted. The interview data was coded and analysed using grounded theory. From the results, two groupings of driver expectations were identified: High Information Preference (HIP) and Low Information Preference (LIP) drivers; between these two groups the information preferences differed. LIP drivers did not want detailed information about the vehicle presented to them, but the definition of partial automation means that this kind of information is required for safe use. Hence, the results suggest careful thought as to how information is presented to them is required in order for LIP drivers to safely using partial driving automation. Conversely, HIP drivers wanted detailed information about the system's status and driving and were found to be more willing to work with the partial automation and its current limitations. It was evident that the drivers' expectations of the partial automation capability differed, and this affected their information preferences. Hence this study suggests that HMI designers must account for these differing expectations and preferences to create a safe, usable system that works for everyone. [Abstract copyright: Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.

Driven to discussion: engaging drivers in conversation with a digital assistant as a countermeasure to passive task-related fatigue

Using a Wizard-of-Oz approach, we explored the effectiveness of engaging drivers in conversation with a digital assistant as an operational strategy to combat the symptoms of passive task-related fatigue. Twenty participants undertook two 30-minute drives in a medium-fidelity driving simulator between 13:00 and 16:30, when circadian and homeostatic influences naturally reduce alertness. Participants were asked to follow a lead-car travelling at a constant speed of 68mph, in a sparsely-populated UK motorway scenario. During one of the counterbalanced drives, participants were engaged in conversation by a digital assistant (‘Vid’). Results show that interacting with Vid had a positive effect on driving performance and arousal, evidenced by better lane-keeping, earlier response to a potential hazard situation, larger pupil diameter, and an increased spread of attention to the road-scene (i.e. fewer fixations concentrated on the road-centre indicating a lower incidence of ‘cognitive tunnelling’). Drivers also reported higher levels of alertness and lower sleepiness following the Vid drive. Subjective workload ratings suggest that drivers exerted less effort to ‘stay awake’ when engaged with Vid. The findings support the development and application of in-vehicle natural language interfaces, and can be used to inform the design of novel countermeasures for driver fatigue

Evaluating secondary input devices to support an automotive touchscreen HMI: a cross-cultural simulator study conducted in the UK and China

Touchscreen Human-Machine Interfaces (HMIs) are a well-established and popular choice to provide the primary control interface between driver and vehicle, yet inherently demand some visual attention. Employing a secondary device with the touchscreen may reduce the demand but there is some debate about which device is most suitable, with current manufacturers favouring different solutions and applying these internationally. We present an empirical driving simulator study, conducted in the UK and China, in which 48 participants undertook typical in-vehicle tasks utilising either a touchscreen, rotary-controller, steering-wheel-controls or touchpad. In both the UK and China, the touchscreen was the most preferred/least demanding to use, and the touchpad least preferred/most demanding, whereas the rotary-controller was generally favoured by UK drivers and steering-wheel-controls were more popular in China. Chinese drivers were more excited by the novelty of the technology, and spent more time attending to the devices while driving, leading to an increase in off-road glance time and a corresponding detriment to vehicle control. Even so, Chinese drivers rated devices as easier-to-use while driving, and felt that they interfered less with their driving performance, compared to their UK counterparts. Results suggest that the most effective solution (to maximise performance/acceptance, while minimising visual demand) is to maintain the touchscreen as the primary control interface (e.g. for top-level tasks), and supplement this with a secondary device that is only enabled for certain actions; moreover, different devices may be employed in different cultural markets. Further work is required to explore these recommendations in greater depth (e.g. during extended or real-world testing), and to validate the findings and approach in other cultural contexts

The comparison of auditory, tactile, and multimodal warnings for the effective communication of unexpected events during an automated driving scenario

In an automated car, users can fully engage in a distractor task, making it a primary task. Compared to manual driving, drivers can engage in tasks that are difficult to interrupt and of higher demand, the consequences can be a reduced perception of, and an impaired reaction to, warnings. In this study we compared three in-vehicle warnings (auditory, tactile, and auditory-tactile) which were presented during three highly attention capturing tasks (visual, auditory, and tactile) while the user was engaged in a self-driving car scenario, culminating in an emergency brake event where the warning was presented. The novel addition for this paper was that three set paced, attention capturing tasks, as well the three warnings were all designed in a pilot study to have comparable workload and noticeability. This enabled a direct comparison of human performance to be made between each of the attention capturing tasks, which are designed to occupy only one specific modality (auditory, visual or haptic), but remain similar in overall task demand. Results from the study showed reaction times to the tactile warning (for the emergency braking event) were significantly slower compared to the auditory and auditory-tactile (aka multimodal or multisensory) warning. Despite the similar reaction times between the in-vehicle auditory warning and the multimodal warning, the multimodal warning led to a reduced number of missed warnings and fewer false responses. However, the auditory and auditory-tactile warnings were rated significantly more startling than the tactile alone. Our results extend the literature regarding the performance benefits of multimodal warnings by comparing them with in-vehicle auditory warnings in an autonomous driving context. The set-pace attention capturing tasks in this study would be of interest to other researchers to evaluate the interaction in an automated driving context, particularly with hard to interrupt and attention capturing tasks

Follow the Leader: Examining Real and Augmented Reality Lead Vehicles as Driving Navigational Aids

Two studies investigated the concept of following a lead vehicle as a navigational aid. The first videobased study (n=34) considered how drivers might use a real-world lead vehicle as a navigational aid, whilst the second simulator-based study (n=22) explored how an Augmented Reality (AR) virtual car, presented on a head-up display (HUD), may aid navigation around a complex junction. Study 1indicated that a lead vehicle is most valued as a navigation aid just before/during a required maneuver. During the second study the dynamic virtual car (which behaved like a real vehicle) resulted in greater confidence and lower workload than a static virtual car that “waits” at the correct junction exit, but resulted in more gaze concentration. It is concluded that a virtual car may be a valuable element of a navigation system, in combination with other forms of information, to completely fulfil all a driver’s navigational task requirements

Investigation of Thermal Stimuli for Lane Changes

Haptic feedback has been widely studied for in-car interactions. However, most of this research has used vibrotactile cues. This paper presents two studies that examine novel thermal feedback for navigation during simulated driving for a lane change task. In the first, we compare the distraction and time differences of audio and thermal feedback. The results show that the presentation of thermal stimuli does not increase lane deviation, but the time needed to complete a lane change increased by 1.82 seconds. In the second study, the influence of variable changes of thermal stimuli on the lane change task performance was tested. We found that the same stimulus design for warm and cold temperatures does not always elicit the same results. Furthermore, variable alterations can have different effects on specified tasks. This suggests that the design of thermal stimuli is highly dependent on what task result should be maximized

Intelligent scheduling for in-car notifications.

The process of driving a car involves a cognitive load that varies over time. Additional load comes from secondary factors not directly associated with the driving process, including navigation devices, entertainment systems and the car’s own warnings. In this paper, we present a framework for intelligent scheduling of in-car notifications based on the driver’s estimated cognitive load. As the single channel for communication, it reschedules the notifications using a priority queue, and relays them to the driver based on the urgency of the notification and the overall estimated cognitive load being experienced by the driver at any given moment. We evaluate our system using a dataset collected from a car’s CAN bus during multiple onroad trials and show that our proposed approach reduces the number of simultaneous calls on the driver’s attention during the driving task. We also demonstrate that our intelligent scheduling significantly reduces the maximum cognitive load experienced by the driver and the frequency with which high loads occur

Research knows best, but how to communicate distraction measures practically in an industrial context

Selection and comparison of human-factors related measures for evaluations of in-vehicle devices involves weighting of multiple criteria. It may result in a complex decision-making process for the practitioner, specifically in a time pressured industrial context. Visual information seeking has successfully been applied to reduce the complexity of datasets in healthcare and other fields. Information is presented visually and divided in ‘Overview’, representing the data by its characteristic criteria, and ‘Details’, which are presented on demand. This division reduces information load for the user and eases comparison based on characteristics. This project, first, aims to understand what criteria practitioners use to decide about the suitability of a measure for an in-vehicle evaluation. Secondly, criteria practitioners use to select measures are implemented in a new interface approach based on methods of visual information seeking to support users in the selection and comparison of human-factors related measures for in-vehicle evaluations. Overall, the interface exposes practitioners to new measures, enables them to rapidly compare measures, and obtain information to practically apply the

Thermal feedback for simulated lane change scenarios

Most research into haptic feedback for in-car applications has used vibrotactile feedback. In this article, two simulator studies investigate novel thermal feedback during driving for a lane change task. The distraction and time differences of audio and thermal feedback were investigated in the first, with results showing that thermal feedback does not increase lane deviation, but the time to completed lane change is 1.82s longer in the thermal than the audio condition. The second experiment explored the difference in variable changes of the thermal stimuli on the recognition rate and false positive recognition at the return to the neutral temperature. Variable alterations can have different effects on these tasks and are not mirrored for the directions of temperature change. This suggests that the design of thermal stimuli is highly dependent on what result should be maximized: recognition rate or minimal additional changes at the return to the neutral temperature

Recreating daylight for readability assessments of in-vehicle displays

This paper describes the early stages of research into defining daylight scenarios encountered by vehicles and outlining which are the worst-case situations with respect to display readability. The main objective of the research is to design a facility capable of recreating a wide range of daylight scenarios to perform controlled, repeatable and reproducible readability assessments within automotive vehicles. This will be achieved through sky luminance mapping, display readability assessments under real skies and investigations into daylighting technologies