RFlow-ID: Unobtrusive Workflow Recognition with COTS RFID

Workflow recognition is a key technique in the field of activity recognition with benefits of monitoring the step being performed in the workflow, detecting the missing step, and providing assistance to the performer of the workflow, among others. In this paper, we present an unobtrusive workflow recognition system called RFlow-ID, which is the first device-free, battery-free and privacy-preserving workflow recognition system based on RFID technique. RFlow-ID perceives the use and movement of associated objects in the workflow using fine-grained phase information extracted from low-level RF signal, and infers the most likely sequence of workflow activities via a VQ-HMM model. We implement RFlow-ID on COTS RFID devices and evaluate it through a common biomedical experiment. The results validate the high recognition accuracy and robustness of our system.