Design Of Acquisition System For High-speed Camera Based On FPGA

With the development of industrial automation,machine vision is widely used in various fields of security,medical equipment,quality inspection,etc.High speed camera is the most important part of Machine vision.Imaging quality and speed of the camera directly affects the machine judgment.In addition,because FPGA has the advantages of fast processing speed and good stability,so the High-speed CCD imaging system based FPGA has become one of the hot spots in the field of image research.Research work carried out in this paper are:Firstly,the image quality of the image acquisition system depends on the design of the analog front end to a certain extent.For the problem of existing area CCD analog front end debugging difficulties and low flexibility,the paper designed a analog front end for area CCD based on FPGA.Taking the interline transfer type CCD sensor named ICX229 AK for example,the working principle and driving schedules of CCD was analyzed.The Altera's FPGA chip was used as the main control system and Verilog HDL was employed to describe the driving sequencer.The designed analog front end has been successfully fulfilled system simulation and verification.The experimental results show that the design of the analog front-end flexibility was greatly improved.Secondly,focus is the key technology of image acquisition system to get a clear image.For the problem of existing area CCD camera autofocus algorithm low accuracy and it is easy that appearing local peak,this paper presents an auto-focus algorithm based on machine learning.Using decision tree algorithm in the machine learning to obtain two decision tree,which to determine the direction and the next step of lens and determine the range of peak.Then the local peak search is performed by using the hill-climbing algorithm to determine the focus peak position.The algorithm is implemented on FPGA.Experimental results show that the accuracy of the auto-focus is improved by 3% and the situation of the local peak has also been reduced.Thirdly,the speed of image acquisition system is mainly reflected in the speed of data processing.For the problem of existing data processing speed of CCD relatively slow,this paper presents an ‘ping-pang structrue' based double SDRAM.Using two pieces of SDRAM realize double port RAM.The selection unit of input data and the selection unit of output data switch each other to achieve seamless data buffer.Experimental results show that the processing speed of this method is34.2MB/s,effectively improved the speed of data processing and transmission.Finally,the paper based on the above work,designed a high speed camera acquisition system based on FPGA.The experimental results show that the acquisition system is designed to meet the design requirements,and it has high application value in industrial field detection and security and so on.