Research Of Linear CCD Image Measurement System Based On FPGA

Image measurement system uses the electronic devices to perceive image features of the objective environment and make use of them in order to achieve detection, control and other purposes. Most applications require non-contact image measurement system for high precision measurements to complete a series of fast processing. Traditional motor speed detection methods are usually based on MCU or industrial computer platform with the software serial mode and by encoder, grating or Hall element, their capability are often limited because of the request of high speed and high precision.Nowadays, the use of linear CCD (Charge Coupled Device) technology for high speed, high precision and real-time non-contact measurement became a reality gradually and achieved good results. What's more, FPGA (Field Programmable Gate Array) is currently the most widely used one of programmable logic devices, it based on hardware parallel processing technology and has a high speed of operation while easy to configure and use. It's very suitable for image measurement system processing core. Brushless DC motor speed detection with the combination of linear CCD and FPGA is the research object in this paper and it has achieved the accuracy and real-time of the system requirements simultaneously.On the basis of the motor speed detection requirements analyzing, this paper focused on the line CCD driver, CCD signal processing by CDS (Correlated Double Sampling) and AD (Analog to Digital) conversion, FIFO (First In First Out) memory and FFT (Fast Fourier Transformation) calculation in FPGA and other functions. In the aspect of software, the principles of auto-correlation algorithm for speed measurements and it's FPGA hardware implementation have also been analyzed. The FFT calculation has been improved for the requirements of real-time system. The drive clock signal and the chip configuration programs by Verilog HDL hardware description language have been designed in the ALTERA QuartusⅡintegrated development environment and have been compiled, simulated and downloaded to the FPGA chip. Finally, the optical measurement platform has been built, and the stability, reliability, good real-time and accuracy of the hardware platform with its relative algorithm program were verified by the contrast experiments.