PostureTag: RFID-Enabled Human Sitting Posture Recognition Using a Tag-Embedded Chair

This article presents a cost-effective wireless approach for identifying human postures using radio frequency identification (RFID) technology. The system uses ultrahigh-frequency (UHF) RFID tags, some embedded in a chair and others integrated inside footwear, to collect information about sitting postures. The novelty lies in the detection procedure, which is a simple and straightforward algorithm that calculates the root-mean-square error (RMSE) between any test dataset and a reference one, encoded by the states of the tags. These states are represented by the normalized counting of the tag electronic product code (EPC) by a reader in a specific time duration. The algorithm is made so that, of all postures under test, the one having the closest data pattern (i.e., minimum error) to the reference will be selected as the correct one. The required quantity and placement of the tags are optimized by looking at a tradeoff between the accuracy and complexity of the system. The proposed method in this stage can reliably differentiate between six primary sitting postures and an empty chair with up to 94%–100% accuracy. It also ensures correct identification even if the user shifts position or rotates relative to the reader.