Driver Activity Monitoring Based On Modulated Frequency Selective Surface and Millimeter-Wave Radar

In-cabin wireless sensors are vital for enhancing road safety and enabling autonomous vehicle technologies. Current vehicles use internal sensors to detect seat belt status, occupant presence, and driver behaviors. Early detection of inattentiveness or erratic driving can significantly reduce accident risks. In this context, this work presents a novel driver activity monitoring system based on a modulated Frequency Selective Surface (FSS), which is read by means of a millimeter-wave Doppler radar for detecting driver head movements. The proposed system offers a non-invasive, privacy-preserving approach by modulating the FSS at two distinct frequencies, enabling precise detection of key head gestures. By focusing on only two modulated frequencies instead of monitoring the entire head and its surrounding area, the system significantly reduces computational complexity and enhances noise immunity, which is essential for in-vehicle applications, where vibrations play an important role. This reduction also simplifies hardware requirements and enables faster, real-time processing, making it highly suitable for integration into Advanced Driver Assistance Systems (ADAS) and vehicle safety monitoring applications. The system aims to distinguish between the driver’s attention and non-attention states. Experimental evaluations demonstrate the system’s effectiveness in achieving this goal while providing lower hardware complexity compared to traditional approaches. By continuously monitoring driver head movements, the proposed system facilitates timely, proactive interventions to mitigate risks and enhance overall road safety.