People with visual disabilities Programmable controllers 6 Blind 4 Ultrasonics 4 Vibrations 4 Automatic speech recognition 2 Blind persons 2 Design and construction 2 Detectors 2 Education (Secondary) 2 Global Positioning System 2 People with disabilities 2 Radio frequency identification systems 2 Self-help devices for people with disabilities 2 Sensors 2 Speech processing systems 2 Design 1 Education 1 User interfaces (Computer systems) 1 Web sites 1