Research On Some Problems For Portable Blind Guided Auxiliary System

Due to the lack of visual perception, it causes great inconvenience for the blind to their daily life and work. Domestic and overseas scholars propose different designs for blind guide auxiliary system, in order to provide the blind walk safely. This paper studies on several important problems of the information collection system, such as acquisition the distance and image information of obstacle, software compression, region location, voice prompt, power controlling etc, which to realize the environment information collection and process real-time for the blind.This paper summarized the development dynamic of blind guiding technology and the advantages and disadvantages of existing blind guided auxiliary system. In-depth study and discussion the existing information collecting technology, for the problems of single way to obtaining the information, large volume, inconvenient portability, which appears in the traditional information collection system. By studying on the image acquisition technology, ultrasonic ranging technology and GPS positioning technology, a design of portable information collection system is proposed. Based on the comprehensive consideration of cost and performance, we choose STM32F417microprocessor as control core, using ultrasonic sensors to detect the distance btween the blind and obstacles, and the distance is compared with the threshold of default distance in the system, as basis whether to open the camera. And the regional information is timing collected by GPS for the blind. These information are compressed before the local storage and wireless transmission, at the same time, the system receive the process results of the information real-time, which come from the information processing center, and in the form of voice to guide blind.In order to improve the efficiency of information transmission between information acquisition and processing system, using software compression algorithm to compress the image information of obstacles. Based on STM32F417development platform, the JPEG compression algorithm of still image coding is realized. Using the powerful DSP and FPU resources of STM32F417, to optimize the key modules and whole implementation process of the JPEG algorithm.Optimization results show that the compression encoder processing a picture of240X320RGB image (data volume150KB) takes only76ms, and the compression ratio can reach14:1.For effectively controlling system power consumption, the low power design scheme of software and hardware are adopted, and energy saving ways of peripheral work method are optimized. Energy conservation methods:ultrasonic ranging in frequency set to30times/min, the ranging error is less than2.68%; image acquisition frequency is60frame/min; every10minutes to open a GPS positioning system, which accuracy is less than10m; voice prompt and compression processing module are automatically enter to the standby mode, after complete a message prompted or a frame of image compressed. The experimental results show that the maximum power dissipation of information collection system is454.56mW. Therefore, uesing two pieces of7400mAh cellphone panels can afford the demand of system power to supply a longer time.The information acquisition system which is studied in this paper has these advantages of rich acquisition information, high real-time performance, small volume, light weight, low power consumption, and easy to carry for the blind, which provides an effective solution for the further research of portable blind guided auxiliary system.