A Design Of The Ultrasonic Phased Array Guidance System For The Blind Based On STM32

In our daily life, ninety-five percent of the information is obtained by eyes. The blinds live in the darkness. There are lots of difficult in their life, work and communication. And the biggest problem for the blind people is how to walk safely. In the world, there are largest number of blind people, and twenty percent of them living in China. To solve this problem, we design a guide system based on ultrasonic phased array. By this system, the blinds can detect the region in front of them without contacting. We aims that the blinds can avoid obstacle with the help of this system.At the beginning of this article we introduced the status of the research in guiding for the blind domestic and international. Currently, there are some primary means used, including guide dogs, satellite guide, radio guide, guide robot and electronic eyes of the blind. In this article we introduced their advantages and disadvantages. So we get the direction of designing.And then we introduced the theory of ultrasonic phased array. This paper describe the method that how the phased array focused at different areas. We control each element's timing sequence to focus in different region by CPLD. At present, the ultrasonic phased array technology has developed fast in various fields. It has large advantages compared to common ultrasonic transducer.We describe the design of the whole architecture in the third part of this paper. In this part, we mainly introduced how the system work and the method of scanning the spatial in front of the blinds. In this chapter we mainly described the design of hardware and soft ware. The system uses multiple ultrasound probe formed phased array. According to certain delay time the phased array can focus at 25 points in front of the blind. So we get a more comprehensive environmental information. There are two parts in this system, including design of hardware and software. The design of hardware includes the circuit of the launching echo signal, low-pass filter section. Emission signal generated by the CPLD, when the signal met obstacle, it will retune back. After amplification by OPA725,the signal will be enlarged to a level that STM32 can recognize. Also we design a communication protocol between CPLD and STM32.By this way, the system can detect certain area in front of the blind. In the system, we used STM32 which was a high-performance launched by ST corporation. And Altera's CPLD chip was used to control the sending timing sequence.And then, we introduced the way of processing the echo. Analysis the different echo signal, we can identify different types of obstacles. So the system will provide necessary information for the blind people.Finally, we summarized this paper and prospected the future work.