Implementation of an Ultrasonic Device for the Visually Impaired

Abstract

An Implementation of Ultrasonic Detector for Visually Impaired Ultrasonic is defined as any bands above audible band (20 kHz) and up to MHz range, and it is widely used in many fields, such as medical, engineering, and military. Another unique characteristic of ultrasonic waves is that it can penetrate opaque materials that other waves cannot. This makes it a very valuable asset to measure distance and thickness of an object in an inexpensive and reliable way. This paper describes a simple and inexpensive but yet reliable ultrasonic device to help the visually impaired people to detect objects several meters away. There are a number of ways to design a device engaging ultrasonic principle. In our approach the detection is initially reflected as a change of duty cycle, and then it is converted into the variation of the frequency, and eventually the user is alerted by the sound from a buzzer. The transmitter sends a continuous 40 kHz signal without modulation. The reflected ultrasonic signal collected by the receiver is very weak, and thus it needs to be amplified and rectified. Two Peripheral Interface Controllers (PICs) are employed in this design. A good feature about this device is that it can updates its readings very quickly, which is required in detecting fast moving objects, such as cars and motorcycles. Most of the components used here are low power chips, hence battery lifetime can be prolonged. The small volume and light weight make it possible to put the ultrasonic transmitter and receiver on someone's arms, which is a convenient way to detect objects on the way ahead.