Haptically Supporting Car Driving: Optimizing or Satisficing?

Abstract – Background: A principal design choice in providing steering wheel force feedback to assist drivers during lane-keeping is whether feedback should be provided for any error with respect to the lane centre (continuous feedback) or only when acceptable tolerance limits are exceeded (bandwidth feedback). Problem: Research has shown that continuously assisting the driver by means of steering wheel force feedback improves driver performance and reduces mental workload. However, it has been suggested that continuous feedback induces aftereffects during subsequent manual driving. Method: In a fixed-base driving simulator study, we evaluated driver performance and mental workload, while drivers (n=32) received corrective force feedback on the steering wheel. Five designs were compared, namely no feedback (Manual), discrete bandwidth feedback (Band1), bandwidth feedback with a hysteresis filter (Band2), continuous feedback with feedback gain used in earlier studies (Cont), and continuous feedback with a feedback gain twice as strong (ContS). While driving the participants performed a secondary peripheral detection task. Participants were told that the feedback was not fully reliable. Towards the end of the trajectory the feedback algorithm was shut down in order to investigate short-term aftereffects. After each trial the participant would fill out a NASA-TLX and a Vanderlaan-questionnaire to measure workload, usefulness and satisfaction. Results: All four feedback designs eliminated the large lane centre deviations that occasionally occur during manual control. Both continuous feedback designs yielded smaller lane centre errors than bandwidth feedback and manual control. Shortly after the feedback was shut down, ContS resulted in worse lane keeping performance than Manual and bandwidth feedback. The secondary task showed a lower reaction time for Cont compared to Band1 and the NASA-TLX indicated lower workload for continuous feedback compared to manual control. The satisfaction scale of the Vanderlaan-questionnaire showed a significantly higher score for Cont compared to Band1. When the feedback shut down, drivers supported by ContS showed a lower minimum TLC, higher mean and maximum absolute lateral error, and more near lane departures. Conclusions: Providing the driver with continuous feedback is an effective way to improve the lane keeping performance and is experienced by drivers as more satisfactory and intuitive, as compared to bandwidth force feedback and manual steering. Bandwidth feedback is equally effective in preventing excessive deviation from the lane centre and did not suffer from the aftereffects that the ContS system did. Stronger continuous feedback resulted in better lane keeping performance, but also in larger aftereffects. The Cont design had a good performance, was perceived as satisfactory and showed no significant short-term aftereffects. Nevertheless, future research should point out if long-term behavioural adaptations lead to stronger aftereffects for continuous systems.BMDBioMechanical EngineeringMechanical, Maritime and Materials Engineerin

Use of auditory interfaces for takeover requests in highly automated driving: A proposed driving simulators study

Highly automated driving can potentially provide enormous benefits to society. However, it is unclear what types of interfaces should be used for takeover requests during highly automated driving, in which a driver is asked to switch back to manual driving. In this paper, a proposal for a driving simulator study on the use of six auditory signals during such takeover requests is outlined. The auditory signals to be tested in the experiment are based on the results of an online international survey previously conducted by the authors. The experiment will involve 24 participants performing a secondary task, and the takeover scenario will be represented by an accident in the middle lane of a three-lane freeway. The time margin prior to takeover will be 7 s. The driving time between subsequent takeover requests will be 2 to 3 min. The application of the results of the proposed study as well as plans for future studies are presented in the last section

Haptic shared steering control with an adaptive level of authority based on time-to-line crossing

Traditional driver-automation interaction trades control over the vehicle back and forth between driver and automation. Haptic shared control offers an alternative by continuously sharing the control through torques on the steering wheel and pedals. When designing additional feedback torques, part of the design choice lies in the stiffness around the neutral steering point: also called the Level of Haptic Authority (LoHA), which is usually static and tuned to balance safety benefits (better at high LoHA) with conflicts torques in case of different intentions between automation and driver (higher conflict torques with increased LoHA). In this paper we explore the idea of situation-adaptive LoHA: in this case during lane-keeping by changing the LoHA based on time to lane crossing (TLC). Consequently, when safety margins are high (e.g., when driving on a wide road) the LoHA is low, but the LoHA would only increase when safety margins decrease. We propose two alternative design approaches to apply the LoHA: symmetrically and asymmetrically (i.e., only increase of LoHA in the direction of the low TLC). We compared these design in an explorative driving simulator study (n=14) to driving with two static LoHA designs (low and high). We found that compared to the high LoHA controller, both adaptive LoHA controllers designs resulted in similar safety margins, but at decreased conflict torques. Hence, a TLC-based adaptive LoHA controller seems to be an effective approach to mitigate conflicts while maintaining the safety benefits associated with HSC.Human-Robot Interactio

The effect of haptic support systems on driver performance: A literature survey

A large number of haptic driver support systems have been described in the scientific literature. However, there is little consensus regarding the design, evaluation methods, and effectiveness of these systems. This literature survey aimed to investigate: (1) what haptic systems (in terms of function, haptic signal, channel, and supported task) have been experimentally tested, (2) how these haptic systems have been evaluated, and (3) their reported effects on driver performance and behaviour. We reviewed empirical research in which participants had to drive a vehicle in a real or simulated environment, were able to control the heading and/or speed of the vehicle, and a haptic signal was provided to them. The results indicated that a clear distinction can be made between warning systems (using vibrations) and guidance systems (using continuous forces). Studies typically used reaction time measures for evaluating warning systems and vehicle-centred performance measures for evaluating guidance systems. In general, haptic warning systems reduced the reaction time of a driver compared to no warnings, although these systems may cause annoyance. Guidance systems generally improved the performance of drivers compared to non-aided driving, but these systems may suffer from after-effects. Longitudinal research is needed to investigate the transfer and retention of effects caused by haptic support systems

Shared control versus traded control in driving: a debate around automation pitfalls

A major question in human-automation interaction is whether tasks should be traded or shared between human and automation. This work presents reflections—which have evolved through classroom debates between the authors over the past 10 years—on these two forms of human-automation interaction, with a focus on the automated driving domain. As in the lectures, we start with a historically informed survey of six pitfalls of automation: (1) Loss of situation and mode awareness, (2) Deskilling, (3) Unbalanced mental workload, (4) Behavioural adaptation, (5) Misuse, and (6) Disuse. Next, one of the authors explains why he believes that haptic shared control may remedy the pitfalls. Next, another author rebuts these arguments, arguing that traded control is the most promising way to improve road safety. This article ends with a common ground, explaining that shared and traded control outperform each other at medium and low environmental complexity, respectively. Practitioner summary: Designers of automation systems will have to consider whether humans and automation should perform tasks alternately or simultaneously. The present article provides an in-depth reflection on this dilemma, which may prove insightful and help guide design. Abbreviations: ACC: Adaptive Cruise Control: A system that can automatically maintain a safe distance from the vehicle in front; AEB: Advanced Emergency Braking (also known as Autonomous Emergency Braking): A system that automatically brakes to a full stop in an emergency situation; AES: Automated Evasive Steering: A system that automatically steers the car back into safety in an emergency situation; ISA: Intelligent Speed Adaptation: A system that can limit engine power automatically so that the driving speed does not exceed a safe or allowed speed.Human-Robot Interactio

Vibrotactile displays: A survey with a view on highly automated driving

The task of car driving is automated to an ever greater extent. In the foreseeable future, drivers will no longer be required to touch the steering wheel and pedals and could engage in non-driving tasks such as working or resting. Vibrotactile displays have the potential to grab the attention of the driver when the automation reaches its functional limits and the driver has to take over control. The aim of the present literature survey is to outline the key physiological and psychophysical aspects of vibrotactile sensation and to provide recommendations and relevant research questions regarding the use of vibrotactile displays for taking over control from an automated vehicle. Results showed that a distinction can be made between four dimensions for coding vibrotactile information (amplitude, frequency, timing, and location), each of which can be static or dynamic. There is a consensus that frequency and amplitude are less suitable for coding information than location and timing. Vibrotactile stimuli have been shown to be effective as simple warnings. However, vibrations can evoke annoyance, and providing vibrations in close spatial-temporal proximity might cause a lack of comprehension of the signal. We describe the sequential stages of a take-over process and argue that vibrotactile displays are a promising candidate for redirecting the attention of a distracted driver. Furthermore, vibrotactile displays hold potential for supporting cognitive processing and action selection while resuming control of an automated vehicle. Finally, we argue that multimodal feedback should be used to assist the driver in the take-over process.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Vehicles & Cognitive Robotic

Use of auditory interfaces for takeover requests in highly automated driving: A proposed driving simulators study

Highly automated driving can potentially provide enormous benefits to society. However, it is unclear what types of interfaces should be used for takeover requests during highly automated driving, in which a driver is asked to switch back to manual driving. In this paper, a proposal for a driving simulator study on the use of six auditory signals during such takeover requests is outlined. The auditory signals to be tested in the experiment are based on the results of an online international survey previously conducted by the authors. The experiment will involve 24 participants performing a secondary task, and the takeover scenario will be represented by an accident in the middle lane of a three-lane freeway. The time margin prior to takeover will be 7 s. The driving time between subsequent takeover requests will be 2 to 3 min. The application of the results of the proposed study as well as plans for future studies are presented in the last section.Biomechatronics & Human-Machine Contro

Ipsilateral and contralateral warnings: effects on decision-making and eye movements in near-collision scenarios

Cars are increasingly capable of providing drivers with warnings and advice. However, whether drivers should be provided with ipsilateral warnings (signaling the direction to steer towards) or contralateral warnings (signaling the direction to avoid) is inconclusive. Furthermore, how auditory warnings and visual information from the driving environment together contribute to drivers’ responses is relatively unexplored. In this study, 34 participants were presented with animated video clips of traffic situations on a three-lane road, while their eye movements were recorded with an eye-tracker. The videos ended with a near collision in front after 1, 3, or 6 s, while either the left or the right lane was safe to swerve into. Participants were instructed to make safe lane-change decisions by pressing the left or right arrow key. Upon the start of each video, participants heard a warning: Go Left/Right (ipsilateral), Danger Left/Right (contralateral), and nondirectional beeps (Baseline), emitted from the spatially corresponding left and right speakers. The results showed no significant differences in response times and accuracy between ipsilateral and contralateral warnings, although participants rated ipsilateral warnings as more satisfactory. Ipsilateral and contralateral warnings both improved response times in situations in which the left/right hazard was not yet manifest or was poorly visible. Participants fixated on salient and relevant vehicles as quickly as 220 ms after the trial started, with no significant differences between the audio types. In conclusion, directional warnings can aid in making a correct left/right evasive decision while not affecting the visual attention distribution.Human-Robot Interactio

Driver response times to auditory, visual, and tactile take-over requests: A simulator study with 101participants

Conditionally automated driving systems may soon be available on the market. Even though these systems exempt drivers from the driving task for extended periods of time, drivers are expected to take back control when the automation issues a so-called take-over request. This study investigated the interaction between take-over request modality and type of non-driving task, regarding the driver's reaction time. It was hypothesized that reaction times are higher when the non-driving task and the take-over request use the same modality. For example, auditory take-over requests were expected to be relatively ineffective in situations in which the driver is making a phone call. 101 participants, divided into three groups, performed one of three non-driving tasks, namely reading (i.e., visual task), calling (auditory task), or watching a video (visual/auditory task). Results showed that auditory and tactile take-over requests yielded overall faster reactions than visual take-over requests. The expected interaction between takeover modality and the dominant modality of the non-driving task was not found. As for self-reported usefulness, auditory and tactile take-over requests yielded higher scores than visual ones. In conclusion, it seems that auditory and tactile stimuli are equally effective as take-over requests, regardless of the non-driving task. Further study into the effects of realistic non-driving tasks is needed to identify which non-driving tasks are detrimental to safety in automated driving.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Biomechatronics & Human-Machine Contro