| In recent years there has been great interest in the positioning of people and assets in indoor and outdoor environments. Many systems were constructed to accomplish this. The application of these systems depends on the environment and the precision required for localization. The Global Positioning System (GPS) cannot be used for a precise indoor localization due to the attenuation and scattering of the signals. For indoor environments, other technologies like Wireless LAN, laser, camera images and motion sensors are used in precise localization. GPS can be used in outdoor environments but if localization accuracy is a critical requirement, other technologies should be used.;An intersecting application scenario for precise pedestrian localization is for the blind and visually impaired. This important segment of our society faces several challenges during daily activities like path planning, navigation and obstacle avoidance. Many of the blind still trust and rely on the white cane to explore their environments. The state-of-the-art white canes have audio systems to guide the blind through their environment. Continuously wearing a headset and hearing sounds can be irritating for some people. Our work provides techniques to fuse data from multiple cost-effective sensors such as Accelerometers, Gyroscopes, Time Difference of Arrival (TDoA) sensors, Wi-Fi and AM radio signals of opportunity. These techniques allow for building autonomous navigation systems for the blind and visually impaired. |
