## 4 Intelligent Wearable Solutions for VRU Safety: Trends, Challenges, and Opportunities
### Wearable Assistive Devices for Visually Impaired Users
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Reference** & **Year** & **Wearable Technology** & **Experimental Validation Method** \\ \hline [PERSON] et al. [56] & 2019 & Intelligent motorcycle helmet with infrared transceivers, camera, and audio system for large vehicle detection & Field testing with 10 motorcyclists collecting 600 images of approaching trucks/buses; tested day and night detection modes \\ \hline [PERSON] et al. [44] & 2020 & Helmet-integrated head-up display (HUD) with V2X communication warning cyclists of opening car doors & Mixed reality study in CAVE simulator comparing baseline with visual and visually-auditory warnings \\ \hline [PERSON] et al. [45] & 2021 & Cycling helmet with four directional tactile actuators for collision avoidance feedback & Field study with 10 cyclists on vehicle-free paths; measured accuracy in identifying direction and proximity of simulated vehicles through head tactile cues \\ \hline [PERSON] et al. [52] & 2021 & Smart scooter system with pressure-sensing insoles for balance monitoring, pothole detection, and path tracking & Field testing with six riders on varied terrains; evaluated balance algorithm accuracy and pothole detection performance \\ \[PERSON] et al. [46] & 2022 & Helmet-mounted HUD with awareness messages for cyclists about opening car doors & Mixed reality simulator study with 24 participants comparing three notification types to baseline \\ \[PERSON] et al. [47] & 2022 & Helmet-mounted HUD with multimodal awareness messages for cyclists avoiding door accidents & Mixed reality simulator study with 24 participants comparing three notification types; evaluated usability, interviewess, user experience, and attitudes \\ \hline [PERSON] et al. [53] & 2022 & Using AR glasses with visual, auditory, and vibrotactile feedback modes to warn of approaching vehicles at intersections & Outdoor experiment with 13 participants using real e-scooters in an AR simulation; compared three unimodal warnings to baseline (no warnings) \\ \hline [PERSON] et al. [48] & 2023 & Smart safety test for cyclists with ESP32, sensors, and LED panels for environmental-based alerts & Lab testing of illuminance sensor accuracy, LED visibility at various distances/angles, GPS tracking, and data logging to web server for route evaluation \\ \hline [PERSON] et al. [49] & 2024 & Smart glasses for cyclists with AR overlays, screen-fixed info, and ambient light displays for traffic hazards & Focus groups with three cycling HCI researchers and four UX design students; developed visual notification concepts and identified challenges in AR registration, distraction, and hazard prioritization \\ \hline [PERSON] et al. [50] & 2025 & Multimodal guidance system with AR displays and haptic vest (40 tactile units) for cyclist traffic awareness & Two studies with 12 participants compared visual feedback types and evaluated unimodal vs. multimodal feedback \\ \hline \hline \end{tabular}
\end{table} 
Table 7: _Cont._impaired pedestrians cross streets safely. In their subsequent research, they optimized this system [79], confirming that shoulder tactile feedback performed best in body orientation mode, significantly reducing users' deviation when crossing streets and establishing the theoretical foundation for multimodal interaction. Meanwhile, [PERSON] et al. developed a navigation system capable of calculating optimal routes based on user preferences [80], providing real-time guidance through voice prompts, significantly enhancing the independent mobility of visually impaired individuals in complex campus environments. To address the challenge of recognizing navigation instructions in noisy environments, [PERSON] et al. innovatively employed non-speech sound beacons to replace traditional voice commands [72], effectively overcoming the limitations of voice instructions in noisy environments and improving system adaptability across various environmental conditions. However, regarding wearable technology applications, [PERSON] et al.