Markers for Automated Vehicles: Technologies, Applications, and Future Directions

Automated vehicles (AVs) heavily depend on sophisticated sensing technologies and advanced algorithms to accurately interpret their surroundings and make safe driving decisions. Despite significant advances in onboard sensors such as cameras, LiDAR, and radar, AV systems still encounter considerable challenges in complex real-world scenarios, including poor lighting, adverse weather conditions, occlusion, and densely populated urban environments. Consequently, external infrastructure solutions have emerged as vital components to enhance AV capabilities beyond onboard sensors alone. Markers, representing infrastructure-based technologies, offer distinct and stable reference points to assist vehicle perception, precise localization, accurate identification, and effective sensor calibration. This study systematically reviews three primary marker technologies: visual markers (e.g., QR codes, fiducial markers), magnetic markers embedded in road surfaces, and wireless tags (e.g., RFID, Bluetooth). For each marker type, we discuss operational principles, highlight key advantages, and analyze inherent limitations. Furthermore, we explore practical applications across various driving scenarios, from structured indoor facilities to challenging outdoor environments, while critically examining deployment challenges including infrastructure costs, environmental sensitivity, and signal interference. Finally, we outline several future research directions emphasizing multimodal marker integration, advanced sensor fusion techniques, and optimized deployment strategies, all aiming to further enhance the robustness and operational safety of automated vehicle systems.