Abstract
The rise of automated vehicles (AVs) has revolutionized transportation, transforming how drivers interact with their vehicles. At Level 3 automation, drivers are relieved from controlling or monitoring the vehicle under certain conditions. However, when the AV encounters situations beyond its operational capabilities, it becomes critical to issue effective takeover requests (TORs) to prompt drivers to resume manual control. Designing intuitive and effective TOR mechanisms is a pivotal challenge in AV human-machine interface (HMI) design.This thesis investigates the use of haptic feedback for TOR design to enhance takeover performance and user experience. The research unfolds in three phases:
1. Meta-Analysis:
A meta-analysis of 19 empirical studies compared the effectiveness of haptic feedback to visual and auditory modalities in TOR scenarios. Sub-group analyses examined the impact of feedback location and non-driving-related tasks (NDRTs) on driver response times. Results indicated that haptic feedback delivered to the hand outperformed seat-based feedback, particularly in realistic scenarios, and was superior to visual or multimodal feedback. This analysis identified research gaps, particularly in the use of mid-air haptic feedback and the application of haptic feedback to facial locations.
2. Mid-air Haptic Feedback on the Face:
To address these gaps, a study evaluated the feasibility of ultrasound mid-air haptic (UMH) feedback on the face using lateral modulation (LM) techniques. The study, involving 24 participants, examined the influence of LM parameters (frequency and amplitude) on perceived intensity, valence, and arousal across different facial sites. Findings revealed that LM amplitude positively influenced perceived intensity and arousal, while LM frequency effects varied by facial location. The lips emerged as the most effective site for delivering mid-air haptic feedback, offering valuable guidelines for designing UMH-based interactions to optimize user experience.
3. Impact of Haptic Feedback Locations and Mid-air Haptic Technology on Drivers’ Takeover Performance and User Experience:
A subsequent study explored the effects of haptic feedback location (hand versus face) and technology (vibrotactile versus UMH) on driver takeover performance and user experience. With 32 participants, results highlighted the significant influence of feedback location on emotional responses and user attitudes, while feedback technology notably affected takeover performance. These findings provide empirical evidence to guide the design of intuitive and effective haptic TOR mechanisms.
Together, these studies advance the understanding of haptic feedback’s role in AV HMI design, offering novel insights for enhancing driving safety and user experience. The findings inform the development of TOR mechanisms that leverage mid-air haptics and facial feedback, paving the way for more effective and user-friendly future AV HMI systems.
| Date of Award | 13 Jul 2025 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Xu Sun (Supervisor), Bingjian Liu (Supervisor) & Qingfeng Wang (Supervisor) |