Dynamic vibrotactile signals for forward collision avoidance warning systems

Abstract

Objective: Four experiments were conducted in order to assess the effectiveness of dynamic vibrotactile collision-warning signals in potentially enhancing safe driving.

Background: Auditory neuroscience research has demonstrated that auditory signals that move toward a person are more salient than those that move away. If this looming effect were found to extend to the tactile modality, then it could be utilized in the context of in-car warning signal design.

Method: The effectiveness of various vibrotactile warning signals was assessed using a simulated car-following task. The vibrotactile warning signals consisted of dynamic toward-/away-from-torso cues (Experiment 1), dynamic versus static vibrotactile cues (Experiment 2), looming-intensity- and constant-intensity-toward-torso cues (Experiment 3), and static cues presented on the hands or on the waist, having either a low or high vibration intensity (Experiment 4).

Results: Braking reaction times (BRTs) were significantly faster for toward-torso as compared to away-from-torso cues (Experiments 1 and 2) and static cues (Experiment 2). This difference could not have been attributed to differential responses to signals delivered to different body parts (i.e., the waist vs. hands; Experiment 4). Embedding a looming-intensity signal into the toward-torso signal did not result in any additional BRT benefits (Experiment 3).

Conclusion: Dynamic vibrotactile cues that feel as though they are approaching the torso can be used to communicate information concerning external events, resulting in a significantly faster reaction time to potential collisions.

Application: Dynamic vibrotactile warning signals that move toward the body offer great potential for the design of future in-car collision-warning system.

Keywords: break reaction time; car following; driving; front-to-rear-end collision; haptic; interface design.

Figure 1.

Schematic bird’s-eye view of the setup used in the laboratory-based Experiments 1, 3, and 4.

Figure 2.

The design and procedure of Experiment 1.

Figure 3.

Mean latency of speeded braking responses (RT; in milliseconds) as a function of the warning signal type and head position in Experiment 1. Error bars indicate the standard errors of the means.

Figure 4.

The driving simulator setup in Experiment 2.

Figure 5.

Mean latency of speeded braking reaction times (in milliseconds) as a function of the warning signal type in Experiment 2. The error bars indicate the standard errors of the means.

Figure 6.

Mean latency of speeded braking responses (RT; in milliseconds) as a function of the warning signal type and head position in Experiment 3. Error bars indicate the standard errors of the means.

Figure 7.

Mean latency of speeded braking responses (RT; in milliseconds) as a function of the type of warning signal and head position in Experiment 4. Error bars indicate the standard errors of the means.