Techniques for Constructing Indoor Navigation Systems for the Visually Impaired: A Review

Sight is an important sensory input for humans to navigate their surrounding environment independently. Tasks that are simple for the sighted are often difficult for a visually impaired person. Throughout the years, many researchers dedicated their time and efforts to design and implement technologies and devices that can help a visually impaired person to navigate in unknown areas independently. An assistive navigation system integrates multiple advanced technologies such as wayfinding, obstacle avoidance, and human-machine interface to assist the visually impaired. Individual components have been explored extensively in the literature and it is a daunting task to review this literature in its entirety. In this article, a compact but comprehensive collection of available methods to build each component is summarized. The discussed methods in this article may have not been implemented for a navigation assistive technology for visually impaired directly but they have great potential to be integrated as an individual building block for this task. Given that every approach has its own challenges, methods to combat those challenges have been presented. The purpose of this article is to present researchers with a comprehensive review of the available components and methods by recapping the essential knowledge to understand the nuances in each component and give them a baseline to start with.