The seamless transition of control between drivers and autonomous systems remains a critical challenge in automated driving, affecting both safety outcomes and overall user experience. To address this challenge, our study examines the effectiveness of two distinct haptic feedback approaches—pneumatic and vibrotactile—when implemented as intelligent interface components for takeover requests (TORs) during these transition periods. We specifically investigate how these haptic modalities can effectively signal drivers when human intervention is required, facilitating smoother control transitions from automated to manual driving. We designed a comprehensive experimental setup integrating these haptic modalities with audio and visual cues and evaluated their performance across nine interaction tasks to understand how multi-modal feedback influences driver responsiveness during takeover scenarios. Our findings reveal that multi-modal approaches incorporating either pneumatic or vibrotactile feedback, combined with standard visual cues, substantially outperform audio-only alerts in both response time and accuracy metrics for takeover requests (TORs). Notably, pneumatic feedback offered more natural sensation and smoother transitions than vibrotactile feedback, with pneumatic systems excelling in comfort while vibrotactile feedback better serves urgent takeovers. This first systematic comparison provides valuable insights for developing interfaces that balance effectiveness with comfort in human-machine systems.

International audience

Social distancing may force people to restrict social touch practices. Our survey (N=136) highlighted substantial social touch breakdowns during the COVID-19 pandemic for semi-intimate relationships (e.g., friends, colleagues), with handshakes being the most reduced, and frustrations at having to re-establish social touch habits. We then designed SansTouch, a multi-modal hand sleeve used together along with a smartphone to enable mediated hand-to-hand interactions such as handshakes or holding hands. To invoke the mediated touch, users synchronously mimic the hand position as in real life while holding SansTouch. Users can feel the touch sensation in real time without touching. Participants from our observational study (N=12) quickly adopted the hand-to-hand interactions of SansTouch for exchanging greetings face-to-face with colleagues and reported stronger preferences towards using SansTouch as opposed to mid-air gestures (e.g., waving). We discuss design implications, including the trade-offs of multi-modality for touch devices in face-to-face communication.

As one of the most important non-verbal communication channel, touch plays an essential role in interpersonal affective communication. Although some researchers have started exploring the possibility of using wearable devices for conveying emotional information, most of the existing devices still lack the capability to support affective and dynamic touch in interaction. In this paper, we explore the effect of dynamic visual cues on the emotional perception of vibrotactile signals. For this purpose, we developed VisualTouch, a haptic sleeve consisting of a haptic layer and a visual layer. We hypothesized that visual cues would enhance the interpretation of tactile cues when both types of cues are congruent. We first carried out an experiment and selected 4 stimuli producing substantially different responses. Based on that, a second experiment was conducted with 12 participants rating the valence and arousal of 36 stimuli using SAM scales.