Esign Of Measurement Platform Of Mid Long-Distance Displacement And Distance Base On Ccd Camera

With the fast development of modern industry, the requirement of measurement is higher and higher. Many measurements are taken place at a special condition in aviation, military, machinery and construction, such as, high temperature, high pressure, high velocity, radioactivity and strong corrosive environment,etc. It is an important practical significance to develop long-distance non-contact measurement.As far as noncontact distance measurement is concerned, ultrasonic-based and laser-based techniques are among the most commonly used methods. Unfortunately, measurement accuracy via the laser-and ultrasonic based methods heavily depended on surface reflectivity of the object under measurement. If the reflection surface is undesired, the measuring system generally performed poorly. The calibration of laser-based instrument is not a trivial issue either since systematic trends could produce the lost of accuracy. Furthermore, these methods have difficulties in recording images of the objects while taking measurement. Alternatively, photogrammetric methods have been proposed for measuring distance as well as determining geometric properties of objects from photographic images. Thanks to the advantages in providing a rich source of environment information, photogrammetric methods have been widely adopted in various applications.However, traditional stereo vision-based systems generally required two cameras displaced horizontally from one another to capture two different pictures for further analysis. As a result, pattern recognition or image analysis of a whole image frame are required to extract and match features from the images for obtaining the distance measurement. Thus, huge amounts of storage capacity and high-speed digital signal processors are required for system so established, inevitably resulting in disadvantages in terms of system complexity, processing speed, and establishment cost. As a result, performance of real-time measurement via the pattern recognition or image analysis methods was generally not satisfactory, particularly for embedded applications, because of the speed constraint.This paper proposes a way of displacement, distance measurement with pixel counts based on digital image processing technology, and design a displacement, distance measurement platform which is composed of image data acquisition system, image data controlling system and image calculating and processing part. This paper includes these researches:1. Controlling system of image data reading and transmission base on SCM is designed and done. It uses AT89S52as MCU chip, which make the whole controlling system simple and effective. We choose CH375as the bridge of data communication because AT89S52cannot read the image data of the camera directly. Because the image data is too large, which is disadvantage for AT89S52to read and transport, we use re-directional of function to resolve this problem and the controlling system will send the image data to the image processing part directly.2. This paper proposes a way of displacement, distance measurement with pixel counts. Because pixel counts is not change while the measured object surface horizontal move, we choose two preference points on the measured object surface and calculate the displacement of measured object with the proportion relationship between the displacement of measured object and pixel counts of reference points. Moving the camera at the photographing direction back and forth, we can get the variation of pixel counts between two reference points and derivate the way of calculating the measured distance.3. Experiment analysis the effect of measuring distance on accuracy of measuring distance and the effect of optical axis deviating angle on accuracy of displacement measurement. Analysis the variation of photographing distance, we get the relationship between variation of photographing distance and measuring accuracy.