View Abstract

The World Health Organization (WHO) reported that there are 285 million visuallyimpaired people worldwide. Among these individuals, there are 39 million who are totally blind. There have been several systems designed to support visually-impaired people and to improve the quality of their lives. Unfortunately, most of these systems are limited in their capabilities. In this paper, we present a comparative survey of the wearable and portable assistive devices for visuallyimpaired people in order to show the progress in assistive technology for this group of people. Thus, the contribution of this literature survey is to discuss in detail the most significant devices that are presented in the literature to assist this population and highlight the improvements, advantages, disadvantages, and accuracy. Our aim is to address and present most of the issues of these systems to pave the way for other researchers to design devices that ensure safety and independent mobility to visually-impaired people.

Protocol Steps

Sensor data collection

Ultrasonic sensors detect obstacles in front of the user by sending ultrasonic pulses and receiving reflected signals

Continuous during operationNot specified

Note: Servo motors provide precise position feedback during detection

View evidence from paper

“Ultrasonic sensors are used for detecting the obstacles. The servo motors are used to give a precise position feedback”

Signal processing by microcontroller

Microcontroller receives and processes data from ultrasonic sensors and servo motors

Real-time processingNot specified

Note: Fuzzy controller makes decisions based on processed information

View evidence from paper

“the fuzzy controller is able to give the accurate decisions based on the information received from the servo motors and ultrasonic sensors”

Feedback generation - audio output

System produces audio messages through speaker to provide navigation instructions to the user

As needed during navigationNot specified

Note: Voice messages provide directional and distance information

View evidence from paper

“The output of the Smart Cane depends on gathering the above information to produce audio messages through the speaker to the user”

Feedback generation - haptic output

System activates vibrator or vibrator gloves to provide tactile feedback to user

As needed during navigationNot specified

Note: Hearing impaired users receive vibration patterns through special gloves with specific meaning for each finger

View evidence from paper

“In addition, hearing impaired people have special vibrator gloves that are provided with the Smart Cane. There is a specific vibration for each finger”

Water detection

Water detector monitors for water presence at specified depth threshold

Continuous during operationNot specified

Note: Water sensor will not detect water unless it is 0.5 cm or deeper; buzzer will not stop until water is dried or wiped

View evidence from paper

“the water sensor will not detect the water unless it is 0.5 cm or deeper and the buzzer of water detector will not stop before it is dried or wiped”

Sensor-Based Assistive Devices for Visually-Impaired People: Current Status, Challenges, and Future Directions

Smart Cane Obstacle Detection

Equipment2

Materials8

Software1

Protocol Steps

Sensor data collection

Signal processing by microcontroller

Feedback generation - audio output

Feedback generation - haptic output

Water detection