The blind are among us. They are ordinary people like us, but they can not see all that we see. Therefore, technology should help them. In the Google Store, we can find applications for the blind. In this article, I will describe two of them and I will present their disadvantages and possible improvements. In addition, I will also show other solution proposed by scientists along with its drawbacks.
The first application is Blind Assistant. It was created by a group of Italian developers and scientists working under the name PhoneScience. It is part of a research project aimed at developing the capacity of modern echolocators to work with non-ultrasonic frequencies. The Google Store offers both a paid and a free version. The second is a test version and is called a Blind Assistant Free. The authors warn that the application may malfunction on some smartphones, but without any details. In this case, the user may use the external devices described on the website Phone Science (http://www.phonescience.eu). The effectiveness of the application depends on the device on which it will start. Authors report that the app works both indoors and outside. However, the wind and various sounds may interfere with its proper functioning.
This app uses the loudspeaker of the device to emit pulse sounds and the microphone for recording the echo. Therefore, we should keep in mind not to cover either the speaker or the microphone and that the loudspeaker should be facing the obstacle so that it can be detected.
In the description of this app on Google Play, we can read that the application:
- has a fast and reliable algorithm
- launches immediately after double-clicking
- has advanced settings
- is user friendly
- has a professional handbook.
The minimum hardware requirements for this application are as follows:
Free version allows to make a echolocation test. In this mode application is testing capabilities of the device on which it is run. The user should find a quiet place, press the START button and approach the wall at a distance of 40 to 70 cm. We can send a report at the end of the test. Application efficiency is higher if the direction of emitted pulses forms an angle of 90° on the reflective surface as shown in the figure below:
The application allows you to set the maximum obstacle distance that will be detected. The choices are 1, 2 and 3 meters. Creators recommend setting a minimum value in the rooms. In addition, the application allows you to set other parameters that affect its operations, such as sensitivity of echolocation, optimization, way of signalling an obstacle (sound or vibration), sound pulses per second, width of sound pulses, volume modulation (switch on or off), recording time. The settings screen is shown in the figure below:
The second application is Pulse Echo Sonar Meter. This application was created by Keuwlsoft. It is available for free on Google Play. It is using audio output to generate sound pulses and microphone to detect echo.
The application description enumerates the following features:
- sampling frequency: 44,1 kHz
- sampling time: from 0.001 to 5 s.
- single / continuous mode
- saving data in CSV files.
When it comes to generating a pulse, its features are as follows:
- type of impulse: single / train / chirp
- impulse course: sinusoidal / square
- pulse frequency: from 20 Hz to 22.05 kHz
- pulse duration: more than 1 second.
The application sets defaults to the propagation of sound as 340.3 m/s, but we can change this value to any other. Sample application screen is shown in the figure below:
At the top we can see two buttons: TIME and DIST. They tell us what value is in the x-axis of the graph: time or distance. The display next to these buttons also shows the time elapsed since the pulse emitted until the echo is detected or the value of the distance travelled by the sound wave. So to calculate the distance from the obstacle we should divide the result by 2.
The top graph shows the recorded level of emitted pulse and echo. In the SCAN tab, you can specify whether there is a single or continuous scan of this level or whether the application is in a paused state.
In the PULSE SOURCE tab, we can set the pulse source to external or internal. In the first case, the application waits for pulses generated outside of it and based on it calculates. In the second case, the application itself generates pulses whose properties can be set when the EDIT PULSE is clicked. Then it is possible to set the type of pulse, its frequency or volume.
The lower display is the visualization of the signal from the last scan.
The documentation does not contain information about the hardware requirements for this application. The creators warn that it can make high pitch sounds, so users should be careful an use, for example, earplugs for more comfortable using.
The results returned by both applications are unreliable and often for the same measurements, they return different distances. However, even assuming that the distances received are one hundred percent true, these applications are not suitable for use by blind people. Firstly, their user interface is very complicated and even people with good eyesight may have trouble to use them properly. The advantage of these applications is that we can set different parameters that affect the measurement, but the way you set them is not suitable for the blind. Another problem is the way they return information about the distance from the obstacle. It is also completely unsuited to the blind. All because this distance is displayed on the screen, which makes it impossible for the blind to know it.
Suggested improvements to adapt application for blind:
- speaking distance
- change settings by voice
- supporting different languages
- starting calculations with a single click.
Another solution for the blind is a special smart bracelet equipped with an ultrasonic sensor that works even in motion and detects obstructions within 4 meters when used in open space and 2 meters away when used in the room. Obstacle information is transmitted in the form of vibration or sound signals. The bracelet was created by Sunu, a company from Boston. It costs $249 and can be ordered on the official website (http://www.sunu.io).
The above figure shows the look of the bracelet from the side, top and bottom. Below is a description of each item in the figure:
- A - an ultrasonic sensor that emits ultrasonic waves and receives echoes obtained during the reflection of these waves from an obstacle.
- B - two buttons allowing to set the range of the bracelet.
- C - a touch panel that allows interaction with the bracelet interface.
- D - input for micro-charger.
- E - hypoallergenic wrist strap with buckle.
However, this bracelet has its drawbacks. First of all, it can not detect sloping and uneven surfaces, curbs and various types of small objects that could endanger blind people. Secondly, it is not waterproof and therefore not suitable for use during rain. In addition, manufacturers warn that the bracelet may not work properly if other ultrasound devices are present, including automatic room lighting.
We can see then, that there is a lot of work ahead of mankind to support the blind as best as possible. Fortunately, the technology goes very fast forward, so maybe all of the above problems will be solved soon.