University of Nevada, Reno computer science engineers have combined human-computer interaction and motion-planning research to build a low-cost, accessible navigation system for people with visual impairments. Called Navatar, the system can run on a standard smartphone.

Existing indoor navigation systems typically require the use of expensive and heavy sensors, or equipping rooms and hallways with radio-frequency tags that can be detected by a handheld reader and are used to determine the user’s location. This has often made the implementation of such systems prohibitively expensive, with few systems having been deployed.

Instead, the University of Nevada, Reno navigation system uses digital 2D architectural maps that are already available for many buildings, and uses low-cost sensors, such as accelerometers and compasses, that are available in most smartphones, to navigate users with visual impairments. The system locates and tracks the user inside the building, finding the most suitable path based on the user’s special needs, and gives step-by-step instructions to the destination.

The smartphone’s sensors, which are used to calculate how many steps the user has executed and her orientation, tend to pick up false signals. To synchronize the location, the system combines probabilistic algorithms and the natural capabilities of people with visual impairments to detect landmarks in their environment through touch, such as corridor intersections, doors, stairs, and elevators.

Since touchscreen devices are challenging for users with visual impairments, directions are provided using synthetic speech. Users confirm the presence of a landmark by verbal confirmation or by pressing a button on the phone or on a Bluetooth headset. A benefit of this approach is that the user can leave the phone in their pocket, leaving both hands free for using a cane and recognizing tactile landmarks.

The team is currently trying to implement their navigation system in other environments and integrate it into outdoor navigation systems that use GPS.

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