There are currently about 285 million people that are visually impaired on the world, 39 million of them are blind. Despite the affectance rate is slightly reducing since the 90s, it stills represent a major health problem that affects more in developing countries.
People with serious visual impairment need to be taught about how to accomplish daily task and travel safely and independently during the daily activities. They usually rely on the use of the white cane to detect obstacles, with a small number employing guide dogs. Local and central governments have also making navigation easier for visually impaired people by adapting public transportation and street furniture to be easier to use by them.
Danger situations in outdoor life
One of the most common fears of visually impaired and partially sighted people is having accident on outdoor activities. Some common causes of accidents are falling from stairs, falling into holes or pits, bumping into objects and collisions with vehicles. Road crossing represents a high risk task due to the different types of crossing, lack of audible semaphores and pedestrian visibility. However, these dangers doesn’t translate directly into heightened risk, since blind and partially sighted people regulate their behaviours in order to avoid these dangers. Some people tend to suppress their pedestrian activity by going out less often or using taxis, which does have an impact on their physical activity and social integration.
Formal road crossings may be controlled (when they have semaphores with fixed time windows or on-demand pushbuttons to request the right of way) or uncontrolled when only black and white stripes are painted on the roadway. Controlled crossings rely on beeping sounds to indicate blind and partially sighted people that they may cross: but, for uncontrolled road crossings, the detection of a stopped vehicle is essential for providing them the peace of mind to initiate the road crossing.
Modern electric and hybrid vehicles
The usage of electric motors as car engines presents the advantage of a quieter functioning mode compared to internal combustion engines, in addition to be more environmentally friendly. The dominant car noise at low speeds is the engine sound, but with electric and hybrid cars it is almost non-existent. That presents a problem to errant pedestrians and visually impaired people.
This problems has been spotted by various blind associations that advocate to include mandatory noise generator on electric and hybrid vehicles that should be activated when the car is in movement at slow speeds. As a consequence, several laws by US government and EU government have been approved, but they won’t be mandatory until 2019. However, these noise generation devices can be deactivated on some situations, and, until cars with these devices appears, there will be a significant number of electric and hybrid vehicles in circulation without these sound generators.
The proposed device aims to detect near electric drive vehicles through its electric motor switching noise. A visually impaired person may use the device to check if it is completely safe to cross a uncontrolled road crossing.
This approach has been used previously by M. Takagi et al at University of Tokyo using the microphone contained in the cell phone to alert pedestrian about near vehicles through wearable devices (Google Glass) using sound fingerprinting to identify vehicles. They have validated the use of sound to detect them earlier than an untrained pedestrian achieving a good accuracy for a initial work.
That same sound detection technique can be used to help visually impaired pedestrians being more safe when crossing the streets. However, some changes to the system can be applied in order to be usable by them, and possibly increase accuracy and range.
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