Automotive human‒machine interface to use like a peripersonal space through the elbow using vibrotactile stimulation
Authors: Furuya Tomokazu , Kawashima Takeshi 
Published: January 2024

Driving a car is a visually demanding task.The ability to convey information intuitively using other senses, rather than relying solely on vision, will significantly reduce the driver's workload. Therefore, we have been focusing on tactile stimuli and the peripersonal space, and the idea of transmitting the relative position and distance of objects around the vehicle to the driver via vibration stimuli applied to the upper limbs. The peripersonal space is the space around the body in which direct interaction between external objects and the body takes place. While driving, the driver monitors the surrounding situation from the front, and there is essentially a fixed relationship between the visual field and the position of the driver's arms. We conceived the idea of transmitting the relative position and distance of objects around the vehicle to the driver via vibration stimulation to the upper limbs by mapping this relationship like a peripersonal space. In a previous study, we investigated the correspondence between visual information presented on a driving simulator and vibration stimuli applied to the hand and elbow. Under such limited conditions, we found that stimuli to the hand tended to correspond to the range of the effective visual field, whereas stimuli to the elbow tended to correspond to the range outside the effective visual field. In the present basic investigation using a driving simulator, we applied tactile stimuli to the elbows to inform the driver about a possible collision with a vehicle pulling in front of them from a blind spot and confirmed the driver's reaction. In the experimental driving scenario, the driver follows behind a vehicle while driving on the left side of a two-lane road. A vehicle in the right lane suddenly cuts in front of the driver when the distance between the two vehicles is 0.5 m. Prior to cutting in front of the driver, the vehicle in the right lane is in the blind spot on the screen of the driving simulator and is completely invisible to the driver because there is no side mirror. The driver operates the vehicle to avoid colliding with the other vehicle. Three conditions were used: condition 1, no vibration stimulation; condition 2, elbow stimulation at a distance of 0.5 m between the vehicle in the right-hand lane and the driver's own vehicle; and condition 3, elbow stimulation at a distance of 0 m between the vehicle in the right-hand lane and the driver's own vehicle. Vibrotactile stimulation was applied twice, separated by an interval of 500 ms, with a tactile apparent motion. The subjects were informed that the tactile apparent motion indicated the interruption by a vehicle from the right-hand lane. The results showed that in condition 3, the timing of braking was earlier than in the other conditions and the distance between vehicles when interrupted by the vehicle from the right lane was large. Future experiments will be conducted to obtain further detailed mapping of the upper limb and visual space and compare the differences with other sensory human‒machine interfaces.