# Implementation of an Obstacle Recognition System for the Blind
## 2 Related Works  
The avoidance of obstacles for blind people has traditionally centered around the use of electronic travel aids (ETA), as documented in previous research [7; 8; 9]. The ETA approach for the blind requires the use of portable-wearable devices containing many electronic sensors that are expensive to manufacture.  
Recently, a study proposed a new navigation aid for the blind that was inexpensive to manufacture and easy to use. The study described a problem encountered by the blind in that they could not easily detect obstacles above their waists or a few feet away [10]. Therefore, a navigation aid system for the blind was suggested that could detect the surrounding environment via several types of sensors. This system consisted of sonar sensors situated on the shoulder for detecting obstacles in front of the blind person, a vibrator on an arm for vibro-tactile feedback, and an ultrasonic can for detecting obstacles on the ground. Detection of the obstacles was controlled by a central micro-controller that connected all the components. The system allowed a person to navigate a 100 m route with some obstacles; however, the system needed a very clean testing environment with little noise. Furthermore, it could only detect the existence of an obstacle, but it could not identify the type of obstacle.  
Later, an obstacle recognition system using radio-frequency identification (RFID) technology was proposed [11]. The system proposed a smart cane outfitted with a Braille display handle. This smart cane could read information provided by RFID tags that were installed in various places. The cane would then analyze the information and display it on the Braille display through the control of electro-mechanical switches. As a result, blind people were able to recognize obstacles via the Braille display. Ultimately, it was determined that the proposed system had several limitations for its adoption in the real world. First, the system did not discriminate between the types of obstacles a blind person could encounter. Additionally, the installation of RFID tags on every surrounding surface was virtually impossible. Even if the installation of RFID tags everywhere was possible to achieve, it would entail a massive cost, as determined by the cost analysis conducted during the study.  
Herein, we proposed an enhanced obstacle recognition system based on the technology of image recognition in real time. Table 1 shows a comparison between the systems proposed in related works and the proposed system of this study. The navigation aid for the blind [10] and the obstacle recognition system using RFID [11] both used several sensors. The navigation aid required ultrasonic sensors to determine if obstacles were in front of the blind, while the obstacle recognition system using RFID required as many RFID tags as the number of obstacles present. Our proposed system does not necessitate the manufacture of anything, nor does it require that expensive equipment be worn. In addition, our proposed system made it possible to recognize an obstacle by using a video input device, namely, a single camera, rather than several types of sensor. It could also recognize the types of obstacles that were in front of the blind.