Feeling Uncertain—Effects of a Vibrotactile Belt that Communicates Vehicle Sensor Uncertainty

Abstract

<jats:p>With the rise of partially automated cars, drivers are more and more required to judge the degree of responsibility that can be delegated to vehicle assistant systems. This can be supported by utilizing interfaces that intuitively convey real-time reliabilities of system functions such as environment sensing. We designed a vibrotactile interface that communicates spatiotemporal information about surrounding vehicles and encodes a representation of spatial uncertainty in a novel way. We evaluated this interface in a driving simulator experiment with high and low levels of human and machine confidence respectively caused by simulated degraded vehicle sensor precision and limited human visibility range. Thereby we were interested in whether drivers (i) could perceive and understand the vibrotactile encoding of spatial uncertainty, (ii) would subjectively benefit from the encoded information, (iii) would be disturbed in cases of information redundancy, and (iv) would gain objective safety benefits from the encoded information. To measure subjective understanding and benefit, a custom questionnaire, Van der Laan acceptance ratings and NASA TLX scores were used. To measure the objective benefit, we computed the minimum time-to-contact as a measure of safety and gaze distributions as an indicator for attention guidance. Results indicate that participants were able to understand the encoded uncertainty and spatiotemporal information and purposefully utilized it when needed. The tactile interface provided meaningful support despite sensory restrictions. By encoding spatial uncertainties, it successfully extended the operating range of the assistance system.</jats:p>

Investigating the Effect of Sensory Concurrency on Learning Haptic Spatiotemporal Signals

“…As described earlier, a number of SSADs have been developed in recent years to support a wide range of user interactions and experiences in different contexts, such as independent navigation using the vOICe [35], FeelSpace [27,38] or EyeCane [34], aiding communication or hearing via the skin [39,51], and augmenting awareness during driving [24,25] or other demanding tasks [6].…”

“…SSADs manifest in the literature through studies exploring feasibility (evaluating device limitations through psychophysics -see Jones [22] for an introduction), practicability (using methodology derived from contemporary HCI research to compare novel SSAD user performance against unaided performance in specific tasks [3,6,7,24,25]), or usability (in-the-wild long-term testing of SSADs with coupled assessments of usability through measurement [37,47] or interview [48]).…”

“…The Lateral Line [25], Feeling Uncertain [24] and ProximityHat [50] allowed users a familiarization time of 5-15 minutes in the context of a simplified or example use-case, before performing a series of device-dependent navigation tasks. As this length of exposure is significantly too short for the development of new sensorimotor skills, these studies may be relying on a degree of "cross-modal skills transfer"; where participants' familiarity with the task enables quick adaptation to receiving comparable sensory information through a new modality [29].…”

“…devices that have been designed to augment or substitute sensory experiences using dynamic, continuous, spatio-temporal signals in response to the user's interactions in a (physical or virtual) environment. Previous work in this area has introduced such interfaces to facilitate demanding tasks in the context of Sensory Substitution and Augmentation (such as sensory impairment aids like the Neosensory Buzz [39] which allows feeling sounds on the arm, or related efforts by Zhao [51] which targets language directly) or driving (The Lateral Line [25] augments driver awareness directly, and Feeling Uncertain [24] arms users with a dynamic awareness of semi-autonomous car sensor uncertainty). Some attempts have been made to produce toolkits for general creation of sensory signals with a variety of input mechanisms, such as TESSA [46] and the TongueDuino [11].…”

Editorial for Special Issue: Test and Evaluation Methods for Human-Machine Interfaces of Automated Vehicles

“…The next paper focuses on the communication of surrounding traffic conditions to users of automated vehicles. The paper "Feeling Uncertain-Effects of a Vibrotactile Belt that Communicates Vehicle Sensor Uncertainty" by Krüger, Driessen, Wiebel-Herboth, de Winter and Wersing [4] deals with the design and evaluation of a vibrotactile interface that communicates spatiotemporal information about surrounding vehicles and encodes a representation of spatial uncertainty in a novel way. For the measure of subjective understanding and benefit, a questionnaire, ratings and scores were used, for the objective benefit, the minimum time-to-contact as a measure of safety and gaze distributions as an indicator for attention guidance were computed.…”