Haptic Seat Research Articles

A Contextual Multimodal System for Increasing Situation Awareness and Takeover Quality in Conditionally Automated Driving

Advanced driver assistances are becoming increasingly common in commercial cars, not only to assist but also to free drivers from manual driving whenever possible. Soon, drivers should be allowed to engage in non-driving-related tasks. The fact that responsibility for driving is shifting from humans to machines must be considered in the development of these assistances in order to guarantee safety and trust. In this article, we introduce AdVitam (for Advanced Driver-Vehicle Interaction to Make future driving safer), an autonomous system aiming at maintaining driver’s situation awareness and optimizing takeover quality during conditionally automated driving. The information conveyed to drivers is dynamically adapted to achieve these goals, depending on the driving environment and the driver’s physiological state. This system consists of three connected modules. The first module (Driver State) predicts the driver’s state with machine learning and physiological signals as inputs. The second module (Supervision) uses different interfaces (a haptic seat, a personal device, and ambient lights) to maintain the drivers’ situation awareness during the autonomous driving phases. The third module (Intervention) is a machine learning model that chooses the most appropriate combination among haptic, auditory, and visual modalities to request the driver to take over control and thus optimize takeover quality. To evaluate the system and each module independently, a preliminary user study with 35 drivers was conducted in a fixed-base driving simulator. All participants drove in two different environments (rural and urban). In addition, the activation of the Supervision and Intervention modules were manipulated as two between-subject factors. Results show that conveying information on the driving environment status through multimodal interfaces increases drivers’ situation awareness (i.e., better identification of potential problems in the environment) and trust in the automated vehicle. However, the system does not show positive outcomes on takeover quality. Besides, the Driver State module provided consistent predictions with the experimental manipulation. The system proposed in this paper could lead to better acceptance and safety when conditionally automated vehicles will be released by increasing drivers’ trust during phases of automated driving.

Effect of multimodal takeover request issued through A-pillar LED light, earcon, speech message, and haptic seat in conditionally automated driving

The driver of a conditionally automated vehicle equivalent to level 3 of the SAE is obligated to accept a takeover request (TOR) issued by the vehicle. Considerable research has been conducted on the TOR, especially in terms of the effectiveness of multimodal methods. Therefore, in this study, the effectiveness of various multimodalities was compared and analyzed. Thirty-six volunteers were recruited to compare the effects of the multimodalities, and vehicle and physiological data were obtained using a driving simulator. Eight combinations of TOR warnings, including those implemented through LED lights on the A-pillar, earcon, speech message, or vibrations in the back support and seat pan, were analyzed to clarify the corresponding effects. When the LED lights were implemented on the A-pillar, the driver reaction was faster (p = 0.022) and steering deviation was larger (p = 0.024) than those in the case in which no LED lights were implemented. The speech message resulted in a larger steering deviation than that in the case of the earcon (p = 0.044). When vibrations were provided through the haptic seat, the reaction time (p < 0.001) was faster, and the steering deviation (p = 0.001) was larger in the presence of vibrations in the haptic seat than no vibration. An interaction effect was noted between the visual and auditory modalities; notably, the earcon resulted in a small steering deviation and skin conductance response amplitude (SCR amplitude) when implemented with LED lights on the A-pillar, whereas the speech message led to a small steering deviation and SCR amplitude without the LED lights. In the design of a multimodal warning to be used to issue a TOR, the effects of each individual modality and corresponding interaction effects must be considered. These effects must be evaluated through application to various takeover situations.

Gaze position modulates the effectiveness of forward collision warnings for drowsy drivers

Advanced driver assistance systems (ADAS) have the potential to prevent crashes and reduce their severity. Forward collision warnings (FCW) are quickly becoming standard across vehicle lineups and may prevent frontal crashes by alerting drivers. Previous research has demonstrated the effectiveness of FCW for distracted drivers, but their effectiveness for other types of impairment remains unknown. Like distraction, drowsiness can impair driver response time and lead to crashes. The goal of the present study was to evaluate the effectiveness of FCW for moderately and severely drowsy drivers using a high-fidelity driving simulator. Drowsy drivers were divided into three warning conditions during a revealed stop vehicle forward collision event: An auditory alert, a haptic seat vibration, and a no warning baseline. Results indicate that FCW were effective at speeding drowsy driver response, but only when the drowsy drivers were looking away from the forward roadway at the onset of the event. These results have important implications for ADAS technology and driver state monitoring systems.

Haptic Seat Interfaces for Driver Information and Warning Systems

The implementation of haptic interfaces in vehicles has important safety and flexibility implications for lessening visual and auditory overload during driving. The present study aims to design and evaluate haptic interfaces with vehicle seats. Three experiments were conducted by testing a haptic seat in a simulator with a total of 20 participants. The first experiment measured reaction time, subjective satisfaction, and subject workloads of the haptic, visual, and auditory displays for the four signals primarily used by vehicle navigation systems. The second experiment measured reaction time, subjective satisfaction, and subjective workloads of the haptic, auditory, and multimodal (haptic + auditory) displays for the ringing signal used by in-vehicle Bluetooth hands-free systems. The third experiment measured drivers' subjective awareness, urgency, usefulness, and disturbance levels at various vibration intensities and positions for a haptic warning signal used by a driver drowsiness warning system. The results indicated that haptic seat interfaces performed better than visual and auditory interfaces, but the unfamiliarity of the haptic interface caused a lower subjective satisfaction for some criteria. Generally, participants showed high subjective satisfaction levels and low subjective workloads toward haptic seat interfaces. This study provided guidance for implementing haptic seat interfaces and identified the possible benefits of their use. It is expected that haptic seats implemented in vehicles will improve safety and the interaction between driver and vehicle.

Driver comprehension of multiple haptic seat alerts intended for use in an integrated collision avoidance system

► A haptic driver seat that intuitively displays seven unique alerts was developed. ► Driver performance was examined as the number of possible alerts was increased. ► Displaying three alerts or less did not degrade driver performance. ► Distracted drivers that received alerts had faster responses to a surprise barricade. ► Alerts evoked through unique/distanced areas that map to desired responses are best. Previous research demonstrated that a haptic driver seat can effectively convey information to drivers, and suggests that it may be an ideal method for presenting haptic information because it maintains contact with the driver. The current study progresses this research by investigating whether a haptic seat can be used as the sole method for communicating multiple and meaningfully different alerts such that drivers quickly execute the correct response maneuver. An intuitive manner for presenting up to seven haptic alerts through the driver seat was developed based on driver performance with an earlier haptic seat design. Twenty-four drivers then participated in an on-road study that, through three experiments, investigated: (1) whether driver response performance to the alerts degrades as the number of possible alerts (one, three, or seven alerts) is increased, (2) whether driver response performance to the alerts degrades when alerts are presented through the same seat location, and (3) whether the haptic seat can effectively alert distracted drivers to a surprise barricade. In Experiment 1, despite drivers always making the correct response maneuver, their manual response time and verbal response accuracy significantly degraded as the number of alerts increased from three to seven. In Experiment 2, drivers’ manual response time significantly improved when alerts were presented through unique seat locations. In Experiment 3, distracted drivers that received an alert returned their gaze to the forward roadway sooner, lifted their foot up from the throttle sooner, and pressed the brake pedal sooner than distracted drivers that did not receive an alert. Overall, the study shows that confusion and delayed responses may occur when the number of possible alerts is increased, but that the information transmitted by the haptic seat alerts can be secured if the alerts are presented through unique seat locations that are spaced far apart, and map to the desired manual response. In balancing the tradeoff between communicating a multitude of information to drivers and minimizing performance decrements, a haptic seat that conveys three alerts is recommended when quick and accurate manual responses are required and additional alert modalities are not utilized. These findings are expected to inform the design of haptic driver seats.

자동차 네비게이션 시스템을 위한 햅틱 시트의 평가에 관한 연구

This study has confirmed that subjective positive and negative aspects a driver feels by applying haptic seat on a vehicle to substantiate vehicle navigation system. Our experiment with total twenty subjects provides that the reaction time (RT) is superior in haptic interface than visual or auditory interface but subjective satisfaction, which subjects feel, and workload is less low in a simulator environment. Although, the difference of individuals and unfamiliarity is relatively high inasmuch as the experiment of absolutely new technology, but overall satisfaction of haptic seat is high. The result of study provides some consideration and direction to need in implementation of a haptic seat and it also confirms their possibility meaningfully. We expect the interaction between a driver and a vehicle and safety improvement potentially through applied haptic seat on actual vehicles.

Identifying the Pattern of Localization Responses with a Haptic Seat Intended to Alert Drivers to the Direction of a Crash Threat

The potential safety benefits afforded by emerging automotive crash avoidance systems may be enhanced by implementing a driver vehicle interface (DVI) that effectively communicates the direction of a potential crash threat in a timely, effective, and integrated manner. An in-traffic study by the authors provided evidence that drivers could spatially map eight haptic seat vibration areas to the corresponding directions surrounding the vehicle with 86% localization accuracy (Fitch, Kiefer, Hankey, &amp; Kleiner, 2007). This paper re-analyzed the data from this study to explore the extent to which there were any notable patterns in the observed localization errors. Results indicate there was some tendency for subjects to perceive side (i.e., left or right) seat pan vibration locations as originating somewhat further back than they actually occurred. Furthermore, the pattern of these errors suggest that a haptic seat communicating four directions of crash threat (e.g., front, right, back, and left) may further reduce the low level of localization errors observed with an eight direction haptic seat design.

Toward Developing an Approach for Alerting Drivers to the Direction of a Crash Threat

This study explored the potential for auditory and haptic spatial cuing approaches to alert drivers to the direction of a crash threat. For an automobile equipped with multiple crash avoidance systems, effective cuing of the crash threat direction may help the driver avoid the crash. Because the driver may not be looking in the direction of a visual crash alert, nonvisual crash alerts were explored as an additional means of directing attention to a potential crash situation. In this in-traffic study, 32 drivers were asked to verbally report alert direction in the absence of any crash threats. Driver localization accuracy and response time were examined as a function of eight alert locations surrounding the vehicle and four directional alert approaches (auditory, haptic, haptic and auditory, and haptic and nondirectional auditory). The auditory directional alert approach used four speakers and broadband alert sounds, and the haptic directional alert approach used vibrations generated at various locations on the bottom of the driver's seat. Overall, relative to the auditory alert approach, the three approaches that included the haptic seat alert component reduced correct localization response times by 257 ms and increased percentage correct localization from 32% to 84%. These results suggest that seat vibration alerts are a promising candidate for alerting drivers to the direction of a crash threat. These findings should facilitate developing a multimodality integrated crash alert approach for vehicles equipped with multiple crash avoidance systems.

Comprehension of Haptic Seat Displays for Integrated Driver Warning Systems

Twenty-two haptic seat collision warning patterns were evaluated in a non-driving context to identify a smaller set for subsequent testing in a driving context. Different patterns were intended to convey blind spot, lane drift, forward collision, and sharp-curve-ahead warnings. Fifty-four test participants experienced a single 2–3 second exposure to each warning pattern while performing a continuous distraction task in a simulator buck with a haptic cushion. The test participant was surrounded by seven static images of driving conditions, one for each warning. The test participant was asked to report his or her association of the experienced haptic pattern with one of the seven driving conditions. The test participant could also respond “I don't know.” The comprehension of several patterns was as good as or better than that recently reported for visual collision warning symbols (Campbell et. al., 2004). One pattern was found that might serve as an excellent ‘general alert’. Some directionally similar patterns were found to degrade comprehension of patterns previously demonstrated to be well understood.