Table 1.

Commonly used sensory aids for visually impaired persons.

Sensor	Cost	Type	Usability
Guide dog	High	Genesis	Not easily available; needs carer
White cane	Low	Mechanical	Slow and can only find obstacles through touch
Ultrasonic sensor	High	Electronic machine	Signal reflection or absorption may result in false information
Camera	Low	Electronic machine	Needs proper installation
Infrared sensor	Low	Electronic machine	Can only be used for short distances
Laser	High	Electronic machine	Sensitive to sunlight
GPS	Low	Electronic machine	Can only be used in outdoors
Mobile robots	High	Electromechanical	Can only be used on plain and smooth surfaces