Wrist-mounted smartphone-based navigation device for visually impaired people using ultrasonic sensing

This paper presents a wrist-mounted wearable device for helping visually impaired people to avoid obstacles and to enable them to move around more efficiently than when using only a white cane. The device is designed to be worn on the wrist of the user and is connected to the user's smartphone. The detection algorithm is based on the information acquired from an ultrasonic sensor on the wristband and the accelerometer in the smartphone. The device has two detection modes; the ground level detection mode, and the above ground level detection mode. The ground level detection mode is used to detect obstacles (both bumps and holes) on the ground based on the distance data from the ultrasonic sensor together with the angle data of the user's arm from the accelerometer. The above ground level detection mode uses solely the information from the ultrasonic sensor. When an obstacle is found, the device alerts the user with both audio and haptic tactile feedback via the smartphone. Experimental results tested on blindfolded sighted individuals show that using the device with a white cane increases efficiency in avoiding obstacles. The results also show that the device is easy to learn.