Research On Speed Measurement Based On CCD Dynamic Response

The speed of moving object is an important parameter when it comes to the moving status of the object. And the measurements of speed have broad application and requirement in production, everyday life and scientific research. Such as measuring the speed of moving car, flying bullets of certain attitude, debris generated from an exploded object, high-speed movement of microscopic particles and so on. In this paper, through analyzing and studying the physical structure and working principle of Charge-coupled Device image sensor (CCD), we propose a speed measurement using single-frame fuzzy image of moving object based on the dynamic response of CCD. Comparing the proposed non-contact measurement based on single frame with the current method based on image sequences, the proposed method is more valid for that the speed measurement could be completed merely using signal-frame image which contains moving information of the moving object. The new method avoids the complex processing of image registration and feature point matching and its arithmetic may be more validate and simple, so the method has certain practicability.The main research of this paper can be concluded as follows: 1. A particular experimental setup is designed upon the mechanism of Charge Coupled Device (CCD), the gray data containing the response information are extracted from the concerned pixels of the motion image, and then the dynamic characteristic was modeled by processing the extracted gray data with Least-square algorithm. The result indicates that the dynamic response of CCD sensors can be expressed as an amended first-order system, a model with agreeable accuracy due to the fitting error approximating to 0.2. Then effect factors of dynamic response of CCD are analyzed and verified by experiments, and the result indicates that the time constant of the amended first-order system which describes CCD dynamic response is in connection with luminance of the object.2. A speed measurement that use single-frame fuzzy image of moving object is designed based on the dynamic response of CCD. In consideration of the engineering application, here we introduce the concept of brightness intensity and calibrate the camera. The time constant of the dynamic response of CCD is the function of gray value and brightness of object. Then the function is established in condition of that the brightness ranges from 700 to 1800lx, exposure time is 1/50 second and aperture is 2.8. Finally, the velocity measurement is conducted when the object is doing one-dimensional movement on a conveyor belt.