Assistive navigation systems for the visually impaired

Navigation systems consist of three main components 1. positioning and tracking 2. pathfinding and 3.guidance. (See Figure 1) The positioning and tracking block determines the position of the user through the use of triangulation or trilateration techniques and tracking is achieved by continuously updating the position of the user. Locating is similar to positioning except that it does not include information on the orientation and direction of the user. This becomes important when working indoors whereby most systems provide location detection rather than the position. The pathfinding block determines routes from between two locations optimised based on traveling time, cost and/or distance. Once the path is determined, the guidance block provides guidance such as turn-by-turn instructions to the user. More advanced systems can determine in real-time the surrounding conditions and guide the user around obstacles.