Blind user wearable audio assistance for indoor navigation based on visual markers and ultrasonic obstacle detection

Abstract

This paper presents an indoor navigation wearable system based on visual markers recognition and ultrasonic obstacles perception used as an audio assistance for blind people. In this prototype, visual markers identify the points of interest in the environment; additionally this location status is enriched with information obtained in real time by other sensors. A map lists these points and indicates the distance and direction between closer points, building a virtual path. The blind users wear also glasses built with sensors like RGB camera, ultrasonic, magnetometer, gyroscope, and accelerometer enhancing the amount and quality of the available information. The user navigates freely in the prepared environment identifying the location markers. Based on the origin point information or the location point information and on the gyro sensor value the path to next marker (target) is calculated. To raise the perception of the environment, avoiding possible obstacles, it is used a couple of ultrasonic sensors. The audio assistance provided to the user makes use of an audio bank, with simple known instructions to indicate precisely the desired route and obstacles. Ten blind users tested and evaluated the system. The results showed rates of about 94.92% successful recognition of the markers using only 26 frames per second and 98.33% of ultrasonic obstacles perception disposed between 0.50 meters and 4.0 meters.