Tham khảo tài liệu 'deploying rfid challenges solutions and open issues part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Use of Active RFID and Environment-Embedded Sensors for Indoor Object Location Estimation 227 Experiment Environment Fridge- X Door ShoesBox--- Chair Table StereoShelf Shelf Fig. 7. Supposed Object Locations and RF Readers KitchenCabinet TVShelf-1 Active RFID Reader Desk DeskCabinet Value of K Fig. 8. Location Estimation Performance by KNN Algorithm 228 Deploying RFID - Challenges Solutions and Open Issues According to Fig. 8 the pattern recognition approach works effectively in discriminating each class from others although there is slight dispersion in estimation performance between different k values. Location estimation based on object motion and human behavior Another approach to improve object localization performance is to make the best use of sensing information. As mentioned before several kinds of sensors are used in our work. Vibration sensors attached inside RFID tags are supposed to provide the system with the information about object motion state whereas sensors embedded in the environment are supposed to provide the information about human behavior and location. It is important to perceive the moment that an object is placed for estimating its location with sensors in the environment effectively. The vibration sensor on each RFID tag offers a great solution to meet this requirement by detecting object motion state. However to integrate the vibration sensors into our system needs another problem to be solved. Generally active RFID tags are produced under the following policies 1 saving the battery 2 miniaturizing the size and 3 cutting down the cost. To follow these policies the frequency of data transmission and the performance of vibration sensor inside are set up to be low. These restrictions cause some significant problems. For example the system cannot detect the moment that object motion state changes in real-time because vibration sensor data requires a moment which is the sampling rate to convey its reaction to the system. In addition .
