Andha Asthra - A navigation system for the visually impaired

There has been a number of attempts to help in the independent travel of the blind. In simple terms they employ techniques to detect the obstacle in front by various methods like ultrasonic, IR, simulating the environment by taking photographs etc. Most practical systems are rather complex and expensive. Therefore, the objective of this paper is to develop a cost effective device that warns a blind pedestrian of obstacles in front of him. After interaction with a couple of blind people, it is observed that they always walk in a straight path and hence require surveillance of path just about 25deg on either side. This paper is based on the principle that if any obstacle is detected in a defined path in the front, then the blind person is given the warning by means of vibrations from a simple vibrator (similar to ones used in mobile phones). An ultrasonic transmitter and receiver pair is strapped on each knee of the user to survey the path. The sensor pairs are placed at different positions so as to detect over hanging obstacles, obstacles on ground and steps.