Accurate positioning using long range active RFID technology to assist visually impaired people

The aim of this paper is to describe a new positioning technique to assist the blind and people with low vision to indicate their location and reach their destinations in both indoor and outdoor environments. The proposed technique is based on a combination of power attenuation and a received signal strength indicator (RSSI) using active radio-frequency identification (RFID) technology. The system uses a mobile reader with a power attenuation feature. RSSI is used as a quantized distance estimator for a short range and in combination with one of eight receiver attenuation level settings for a wider range of up to 70 m. A Global Positioning System (GPS) works efficiently in a similar environment but is only accurate to around 10-20 m and does not work efficiently in indoor environments. This research produced a system that identifies various locations such as offices, laboratories, theaters to assist users in reaching their destination of interest. It was then implemented in an indoor environment as an empirical case study to identify laboratories based on a combined technique with a successful identification rate of around 98%. The reader has eight attenuation settings, and the geographic range of each level using various tags was calculated. Then, to evaluate reliability, 6 experiments with 108 samples were conducted using three tags with distances from 1 m to 25 m, using power settings 1-6. A successful detection rate of 93.5% was achieved, as well as a false positive rate of 1%. Following this, the system was implemented in a park to evaluate its ability to indicate the position of the reader among a grid of tags in an open area. A satisfactory result was achieved. (C) 2013 Elsevier Ltd. All rights reserved.