Frequency Modulated Continuous Wave Millimeter-Wave Radar for Vehicular In-Cabin Sensing: Child Presence Detection and Beyond

To ensure passenger safety, contemporary vehicle designs require robust systems of in-cabin child presence detection (CPD) that adhere to stringent standards or regulatory requirements. These systems are expected to accurately classify children, adults, and nonhuman objects with 100% accuracy and zero false alarms in less than 10 seconds. Challenges have persisted for years to achieve highly reliable CPD using frequency modulated continuous wave (FMCW), particularly in missed detections and high detection precision for small displacements. This article presents integrated design strategies, wireless intelligent sensing (WISe), for mitigating these challenges and implementation details of the FMCW-based CPD system. Key hardware design guidelines and software methodologies for enabling WISe are highlighted in this article. First of all, a co-design approach for hardware is introduced, including the transmitting and receiving antenna isolation influence on the signal-to-noise ratio (SNR) of the radar systems. Second, software strategies are presented to enhance signal processing and data extraction, leveraging spatial-temporal features from point clouds (PCs) and vital signs for accurate and reliable classifications. Future applications of FMCW radar for advanced vehicular in-cabin sensing are also discussed.