Generalized RFID Control Using Posture Effect on Tag Detection for Vision Impaired

Abstract

This project is about the design and implementation of generalized RFID control using posture effect on tag detection for vision impaired (or visual impairment person, VIP). There are two parts in this work including VIP’s Radio Frequency Identification (RFID) cane design and test using UHF RFID passive tag operated at 920 MHz and; Received Signal Strength Indication (RSSI) of UHF RFID tag attached to the cane in different orientation is used to realize generalized control mechanism for VIP. To validate the system practical, a prototype UHF RFID cane and its control system is designed and tested aligned with possible postal service for VIP in Macau. It is believed that such RFID cane based on passive tags allows an implementation of economic and smart information system development for VIP in future.

For the design of RFID cane, a two-tag cane with 100 cm length is studied in consideration of tag’s linear polarization. These two tags are arranged around 70 cm in horizontal and vertical position respectively in reference to the cane end. For a trial tag detection in 110 cm apart from the reader, due to the polarization effect of VIP’s cane vertically holding posture, the horizontal and vertical tags provided -64 dBm and -74 dBm of RSSI respectively whilst the horizontal posture holding only reported -55 dBm and 0 dBm of RSSI yielding more than 10 dB and 50 dB differences. Therefore, a control mechanism of “ON” and “OFF” signal can be differentiated. Additional tag-reader distances were studied, 8 dB, 3 dB, 7 dB for 120 cm, 160 cm, 190 cm when posture effect was implemented by different holdings of the cane with different angles. Moreover, the experiment aimed to test about whether the materials such as iron, copper and plastic will affect the effectiveness of the tags or not had been included in this project.

Nowadays, the postal service for VIP needs further attention in Macau. The above RSSI signal phenomena of two-tag RFID cane was used to develop a RFID enable postal service for VIP. In fact, the control system for the function of printing, voice to text or “Text to Voice” can be integrated to build a “Kiosk”. According to principle of the control mechanism of “ON” and “OFF”, the “Kiosk” can acts as a postal services center with different functions which is controlled via the different holdings of the RFID cane.