The Design Of Path Recognition Image Sensor Based On FPGA

Vision navigation based on colorized path recognition is the hotspot and aspect of the research in all the guidable means for AGV. Vision navigation is a way that controls the direction when vehicle moving based on the positional difference between the path and the vehicle, so, incepting and processing the colorized path image is the base and pivotal approach in it. In the current design of vision guide system, general CPU, embedded CPU and DSP are the foundations of the hardware platform. A common characteristic of these processors is that they deal with the data in series, whereas image recognition arithmetic requires a mass of parallel operation, accordingly, the traditional processing in series can not satisfy the demand for real time.As the shortage of micro CPU in this aspect, the author proposes a scheme of using FPGA to implement the parallel computing, and designs an intelligent image sensor system. The sensor adopts the advanced FPGA chip technology, makes many functional modules into one chip, including the image gathering and displaying, path identification and communication control and so on , which forms a SOC system. The primary function of this sensor is distinguishing the path from the image and computing the coordinate and orientation of the colorized path, and sending out the result to upper computer.The paper divides the course of image processing into three phases. The first one is obtaining a binary image via color clustering segmentation. The second one is filtering the black spot in the binary image using the tool of mathematical morphology. The third one is measuring the coordinate and direction-angle of the path. The image sensor communicates with the upper computer via UART. Owing to the upper computer needs the image sensor to implement manifold task, the author even defines an application layer protocol, which is applied to control the sensor by upper computer. For matching the speed of image gathering and showing, the author also devises a frame buffer mechanism for image display based on single port memory, and the image will be displayed on a screen through VGA interface in real time.With the thinking, the author has made a circuit board according as the sensor principle and debugged it. The results show that all the modules perform very well in the working process, and the digital logic circuit in FPGA can identify the path in real time. It incarnates adequately the advantage of image processing based on parallel computing.