## 4 Intelligent Wearable Solutions for VRU Safety: Trends, Challenges, and Opportunities
### Wearable Assistive Devices for Visually Impaired Users
Regarding feedback mode selection, a comparative study by [PERSON] et al. [8] found that although visual feedback (LED light strips) had certain advantages in decision-making efficiency, most visually impaired users still preferred the comfort and intuitiveness of tactile feedback (vibration vests). These systems are particularly suitable for noisy environments and scenarios requiring auditory perception of environmental sounds, providing visually impaired individuals with a supplementary perception channel beyond hearing. Research trends indicate that this field is moving toward more refined vibration encoding, expressing richer spatial relationship information through varied vibration patterns. Despite tactile feedback's excellent performance in noisy environments, its limited information transmission capacity makes it difficult to express complex scene details, a limitation that has driven the development of more comprehensive head-mounted systems. Beyond tactile feedback systems, smart glasses and head-mounted systems have gradually become mainstream in assistive research for the visually impaired due to their convenient wear and natural field-of-view advantages, demonstrating a development trend from single feedback to multimodal integration. [PERSON] et al. designed an electronic glasses system that provided obstacle warnings through single-ear headphones or wrist vibrators [57], enabling users to correctly identify obstacle positions in a short time and effectively enhancing environmental perception capabilities. In technical implementation, the glasses system of [PERSON] et al. innovatively applied perspective projection geometry to measure grid shape changes [81], providing directional auditory feedback through Bluetooth headphones and achieving significant progress in the accuracy and processing speed of obstacle detection. Addressing the critical scenario of traffic safety, [PERSON] et al. developed specialized systems for crosswalk navigation [82] and intersection navigation [83], using head-mounted cameras and bone conduction headphones to identify crosswalks and traffic light status in complex environments, improving the crossing safety of visually impaired pedestrians. [PERSON] et al. conducted two in-depth studies based on this foundation [58; 59], further enhancing the accuracy and fluency of visually impaired pedestrians in crosswalk navigation by optimizing traffic light recognition algorithms and navigation instruction systems. Recent research shows a trend toward multisensory integration, with [PERSON] et al. combining 3D spatialized sound technology with helmet-mounted cameras [60], creating a more intuitive obstacle perception experience, and the smart glasses and smartphone combination system of [PERSON] et al. integrated advanced computer vision and multisensor fusion technology, providing dual voice and tactile feedback and achieving a 100% obstacle avoidance rate in complex indoor and outdoor environment tests [6]. With the advantage of simulating natural visual perception processes, these systems are particularly suitable for complex street and traffic scenarios. Research trends indicate the field is moving toward multisensory integration and full-scenario adaptability, providing more intuitive and precise environmental understanding capabilities through the integration of advanced sensors and intelligent algorithms. However, even the most advanced single-type systems struggle to meet the needs of visually impaired users in all scenarios, a recognition that has prompted researchers to further explore multimodal systems that deeply integrate the advantages of different technologies. From the perspective of overall technological evolution, multimodal systems embody the convergent development direction of assistive technologies for the visually impaired by integrating different types of sensors and feedback methods. [PERSON] et al.