Blind Navigation via a DGPS-based Hand-held Unit

This research explains the development of a hand-held DGPS (Differential Global Positioning System)-based mobile navigation unit, established for the guidance of blind and partially sighted pedestrians. The designed hand-held unit may easily be carried by visually impaired pedestrians to navigate themselves. In this paper the development of a micro-controller based hand- held unit was demonstrated, that is slightly larger than an average mobile telephone handset. The software development of the hand-held unit was done in assembly language and communication has been established with a GPS receiver and a cellular mobile telephone. The software is developed in two different modes, i.e. DGPS and Inverse-DGPS. Static experiments were performed using the designed hand-held unit. These experiments were performed in GPS mode in both cases, i.e. in the presence of Selective Availability (S/A) and the absence of S/A. These experimental results demonstrated that the performance of the system is much improved in the absence of S/A. Another set of experiments were performed in DGPS mode, that showed the positioning accuracy of the developed hand-held unit well within 5m circle around the marked reference points. The results of these experiments also depict the suitability of developed hand-held system for the navigation of blind and partially sighted pedestrians.