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“A system was developed to help blind people to obtain information about theenvironment in their surroundings as shown” in Figure (2-1a & 2-1b). By using 3D “scanner and small PC, the system manages to detect anobstacle and acquires 3D range data map” of theenvironment and gives information to theuser by the synthesized sound. “The advantages of this system are it has clear object detection because it using 3D scanner”placed on the chest of the user and the angle of detection “is large enough to detect obstacle and alert the user. However, the problem of this system is the cost of this” system is very expensive since it “using the3D scanner and small PC and it is also heavyweight resulting inconvenient for the user”.
“The purpose of this research is to develop a system which gives blind people information of the environment around them”. A person is equipped with a 3D scanner and a small sized PC while “walking. The scanner scans and acquires 3D range data map of the environment”. The PC analyzes the range data map and detects objects which are useful for blind people in order to walk. “The PC gives environmental information to them by synthesized sound”. This paper first introduces the concept of the whole system and clarify the tasks for realizing the system. Secondly, the method for acquisition of 3D range data and detecting objects and obstacles are described. Then the usefulness of our proposed system is examined by an experiment in which our trial system detects bumps and trenches in the experimental environment.
In a stick that has the ability to stand alone was develop to help blind people facilitate movement as shown in Figure 2.3. The system equipped with amicrocontroller, ultrasonic sensor and buzzer provide a practical system that can help theuser to walk and perform daily activities. The system has their specification which contributes to a good design of thedevice. It is very comfortable to use this device because it has the ability to standaloneand theuser will not find difficulties to carry this device and the addition of the shoulderstrap make it more convenience for theuser. Although it is comfortable and convenience for theuser, but it also has limitation and can affect the safety of the user. Since it only uses buzzer and placed at the middle of the stick, there will be a problem if the user enters the noisy environment. The user cannot hear the sound because the buzzer is too far from the user.
A navigation aid for the blind using echolocation principle and ultrasonic sensors. The device is for obstacles avoidance by detecting near objects in front of the user and shall trigger an audible alarm. Based on the echolocation principle, the ultrasonic beam is emitted in a certain direction in space through a transmitter. The beam is reflected from objects it encounters on its way; a matching receiver detects the reflected beam and the distance to the objectarecalculated based on time difference between emitting and receiving beam. Experimental results are presented. It could plausibly deduce that the device produced is suitable to be used as a navigation aid for the visually impaired.
This system uses ultrasonic sensors are used to calculate thedistance of the obstacles around the blind person to guide the user towards the available path.The output is in the form of voice which the blind person can hear e.g., right, left etc. In its advance mode, the system will be able to recognize objects using image processing algorithms.The system block diagram is shown in figure 2.5. From thefigure, we can see that the system consists of amicrocontroller, camera, ear speaker, ultrasonic sensors, EEPROM, digital to analog converter. The system can function in two modes, WALK mode, and CAM mode. In WALK mode, the system uses ultrasonic sensors to detect anobstacle and the voice command will guide the user to the right direction via ear speaker. In CAM mode, the vision camera is used to help the blind people in recognizing objects and text. Figure 2.4 shows hardware setup of the system.
This system can give the direction guidance accurately as the ultrasonic sensors are placed with anangle so that the sensors can detect the obstacle from many directions, including the dig. However, this system cannot determine the distance between the obstacle and user and give an instruction on it. Since this system did not involve white cane, this will very dangerous to the user.
The Guide Cane is actually same like white cane because the user needs to hold the cane in front of them while walking. Although it is considered heavier than the white cane, but it rolls on wheels that support the Guide Cane’sweight during regular operation. A servomotor is controlled by the built-in computer to steer the wheels left and right relative to the cane. Both wheels are equipped with encoders to determine their relative motion. TheGuide Cane is equipped with ten ultrasonic sensors in order to detect anobstacle. To specify a desired direction of motion, the user operates a mini joystick located at the handle. Based on the user input and the sensor data from its sonar and encoders, the computer decides where to head next and turns the wheels accordingly. Whiletraveling, the ultrasonic sensors can detect any obstacle in a 120° wide sector ahead of the user (Step 1 in Figure 2.8). The sensors data will be received by the built-in computer and determine an appropriate direction of travel instantaneously. If an obstacle blocks the desired travel direction, then the obstacle avoidance algorithm prescribes an alternative direction to avoid the obstacle and then resumes in the desired direction (Step 2 in Figure
2.8). Once the wheels begin to steer sideways to avoid the obstacle, the user feels the resulting horizontal rotation of the cane (Step 3 in Figure 2.8).The user’s trajectory is very close to the GuideCane’s trajectory because itshandle is short. After the obstacle is cleared, the wheels steer back to theoriginallydesired direction of travel immediately, although the new line of travel will be offset from the original line of travel. The GuideCane can provide an accurate direction guideline to the user since the built-in computer can determine an appropriate direction of travel instantaneously afterreceiving the sensor data. The servomotor acts as a robotic guidedogto lead the user to the correct direction by turning the wheels to left or right. But, the size of the GuideCane is slightly larger and this will make the user inconvenient when walking to the street with many people. The placement of the ultrasonic sensor is slightly lower will cause the detection range of the ultrasonic sensor slightly drop as the sensor cannot detect the obstacles which just slightly higher. The use of ten ultrasonic sensors will cost a lot of money.
In this paper, an ultrasonic direction system for blind people is developed without awhite cane by using amicrocontroller. This system consists of a microcontroller, an accelerometer, a footswitch, a speech synthesizer, a hexadecimal keypad, a mode switch,
Two ultrasonic sensors, two vibrators and a power switch. Figure 2.9 shows the block diagram of the system. Basically, this system has several functions. First of all is the obstacle detection function. This system detects the obstacle by using two ultrasonic sensors and gives direction instruction to the user by vibration. For example, if left ultrasonic sensor detects anobstacle, then the left vibrator will vibrate. The vibration will increase if the distance between the user and the obstacle decrease and the vibration will decrease if the distance increases. Next, this system also acts as a ‘Micromax’, which means that the system can record and playback the direction instruction of a journey. In record mode, theuser walks the route of interest, and the aid measures the distance traveled by the user. When theuser reaches a decision point, for instance, a point at which the route takes a left turn, the user presses a key on the aid coded with a left turn instruction. Then, the distancetraveled will be stored in the memory in themicrocontroller. The user repeats this step for the next decision point until reach the destination. The user can make any of this decision turn left, turn right, cross road, cross road junction, pedestrian crossing, steps, pause, and stop. In the playback mode, there are forward and reverse directions. The aid measures again the distancetraveledby the user. When this is equal to that stored in the memory for that particular section of the route, a corresponding decision word generated by the synthesizer is given to the user. The audible signal indicates what action the user should take at this point, for instance, turn left. In the reverse direction, the procedure is exactly the same except that the route information stored in the memory is used in reverse order, and that right and left are interchanged this system is very user-friendlyas the system consists of multifunction. However, the placement of ultrasonic sensors at the shoulder of the user is too high will cause the ultrasonic sensors cannot detect the obstacle at alower level. If the user does not hold a white cane, this will very dangerous to the user.
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Figure 2.10 |