Many studies are made to find a better way to assist the autonomous walking of blind people. The more diffuse and simple instrument used today is still the white cane although the great research made on the electronic travel aids (ETA). These devices have the task to assist blind people to intercept obstacles on their path. The common technologies used for this task are: Camera, GPS, Wireless sensor networks and ultrasonic and infrared sensors.
The devices based on camera work by processing images and by translating them into sounds, vibrations or verbal messages. The GPS technology is commonly used to know the exact position and to conduct blind people to their destinations by verbal messages. A similar approach, but using a wireless sensor network, is presented in work in which the wireless network is used to find the exact position optimized by a triangulation of sensors. Other different approaches to the problem is the interception of immediately obstacles to the user by using detention sensors like ultrasonic and infrared. The main task of these devices is to intercept the obstacles by a variation of the distance between it and the user. The output signals are usually the same of the other devices based on the other technology.
In the work entitled "A new hybrid infrared-ultrasonic electronic travel aids for blind people" the authors present an hybrid device based on two infrared and one ultrasonic sensors. The authors think that this approach has the goal of simplicity and is very cheap in comparison with a lot of other technology especially with those based on the image processing. This reduction of components comports a little consumption of energy and then a great autonomy. On the other hand the hybrid approach, combined ultrasonic and infrared technology, allows to take the best property of the two kind of sensors. The ultrasonic sensor has the possibility to intercept any kind of surfaces in contrast to the infrared one that cannot intercept glass or mirror. On the contrary the infrared sensor has the property to have a little spot, with respect to the ultrasonic sensor, then gives the possibility to intercept better the position of an obstacle.
The new ETA implement a device with the two infrared sensors, disposed one on the left and one on the right side of the user, that aim, each one, in front of the foot where they are located. All the components of the device are integrated in a belt that is easy to dress and is not very wearable like clothes or shoes.
The recognition of the different kind of obstacles is given by the different output signals that can increase or decrease in intensity respectively at the increasing or decreasing of the obstacle dimension. The simplicity of the output signals that the user have to learn to interpret is the goal of this device, for this reason the device takes the informations strictly necessary on the surroundings of the user and give to her/him only two kind of signals for each foot, depending on whether the obstacle is positive or negative. The introduction of the ultrasonic sensor, as after explained, is due only to functional reasons and to make more reliable the system.
The devices based on camera work by processing images and by translating them into sounds, vibrations or verbal messages. The GPS technology is commonly used to know the exact position and to conduct blind people to their destinations by verbal messages. A similar approach, but using a wireless sensor network, is presented in work in which the wireless network is used to find the exact position optimized by a triangulation of sensors. Other different approaches to the problem is the interception of immediately obstacles to the user by using detention sensors like ultrasonic and infrared. The main task of these devices is to intercept the obstacles by a variation of the distance between it and the user. The output signals are usually the same of the other devices based on the other technology.
In the work entitled "A new hybrid infrared-ultrasonic electronic travel aids for blind people" the authors present an hybrid device based on two infrared and one ultrasonic sensors. The authors think that this approach has the goal of simplicity and is very cheap in comparison with a lot of other technology especially with those based on the image processing. This reduction of components comports a little consumption of energy and then a great autonomy. On the other hand the hybrid approach, combined ultrasonic and infrared technology, allows to take the best property of the two kind of sensors. The ultrasonic sensor has the possibility to intercept any kind of surfaces in contrast to the infrared one that cannot intercept glass or mirror. On the contrary the infrared sensor has the property to have a little spot, with respect to the ultrasonic sensor, then gives the possibility to intercept better the position of an obstacle.
The new ETA implement a device with the two infrared sensors, disposed one on the left and one on the right side of the user, that aim, each one, in front of the foot where they are located. All the components of the device are integrated in a belt that is easy to dress and is not very wearable like clothes or shoes.
The recognition of the different kind of obstacles is given by the different output signals that can increase or decrease in intensity respectively at the increasing or decreasing of the obstacle dimension. The simplicity of the output signals that the user have to learn to interpret is the goal of this device, for this reason the device takes the informations strictly necessary on the surroundings of the user and give to her/him only two kind of signals for each foot, depending on whether the obstacle is positive or negative. The introduction of the ultrasonic sensor, as after explained, is due only to functional reasons and to make more reliable the system.
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