Linear Array CCD Camera Research Articles

Measurements of solid volume fraction and granular temperature at granular avalanches in a drum

A granular flow in the drum has high heat exchange efficiency and mixing efficiency, and is widely used in industrial productions. Accurately describing the flow properties is extremely important for industrial production. In this work, an image measuring device based on area array CCD camera and a Speckle Visibility Spectroscopy (SVS) measuring device based on linear array CCD camera were established. Spherical particles having a mean particle diameter of 0.5 mm and irregular particles having an equivalent particle diameter of 0.5 mm were used. By measuring the profile of the side surface of the granular system in the drum, the volume fractions before and after the avalanche of the granular system were calculated. It was found that both the spherical particle system and the irregular particle system expanded during the avalanche process; before the avalanche, the irregular particle system was compacted, while the spherical particle system did not compact. Furthermore, granular temperature at different locations on the free surface of the granular flow was measured. It was found that the avalanche of the spherical particles and the irregular particles occurred at the same position; the compaction of the irregular particle system first occurred in the upper half of the system, and the compaction phenomenon occurred only once during one avalanche cycle time. Finally, based on the side surface profile and granular temperature, the angle of repose and characteristic time parameters were measured. It was found that the relationship between the angle of repose of the spherical particle system and the avalanche time was consistent with the model proposed by Davidson, and the compaction of the irregular particle system before avalanche would shorten the avalanche time of the particles. The experimental results obtained in this work provide reference data for improving the precise control technology of the flow and heat transfer of the granular materials in industrial productions.

Computer vision for yarn microtension measurement.

Yarn tension is an important parameter for assuring textile quality. In this paper, an optical method to measure microtension of moving yarn automatically in the winding system is proposed. The proposed method can measure microtension of the moving yarn by analyzing the captured images. With a line laser illuminating the moving yarn, a linear array CCD camera is used to capture the images. Design principles of yarn microtension measuring equipment based on computer vision are presented. A local border difference algorithm is used to search the upper border of the moving yarn as the characteristic line, and Fourier descriptors are used to filter the high-frequency noises caused by unevenness of the yarn diameter. Based on the average value of the characteristic line, the captured images were classified into sagging images and vibration images. The average value is considered a sag coordinate of the sagging images. The peak and trough coordinates of the vibration are obtained by change-point detection. Then, according to axially moving string and catenary theory, we obtain the microtension of the moving yarn. Experiments were performed and compared with a resistance strain sensor, and the results prove that the proposed method is effective and of high accuracy.

Measuring principle of vertical target density based on single linear array CCD camera

In consideration of the complexity and the high cost of the dual CCD intersection vertical target when it is used indoor. A novel measuring principle of one linear array CCD camera vertical target is presented. One low-power semiconductor sector-like laser with projection board is used to be the lamp-house of the CCD camera. The detection light screen of the CCD camera and the laser lamp-house are adjusted to same plane. When the projectile through the detection light screen, it blocks the part light of the laser and leaves a shadow of projectile on the board. The shadow and its coordinate are acquired and calculated by the CCD camera and computer, and the projectile coordinate of X and Y can be gotten through image processing and further calculation. The measuring principle and the formulas are given, and the measuring error is analyzed. The result indicates that the coordinate error of X and Y less than 1.5 and 2.2mm, respectively, when the detection light screens is 1m×1m, The principle presented has the advantages that measurement principle is simple, low cost and easy engineering.

Focal Length Measurement of Lens Based on Linear Array CCD

Focal length of lens is an important parameter to determine the relationship between objective and image. It must be measured accurately. The traditional method of using optical bench to measure the focal length of lens has big man-made errors. So we used linear array CCD camera instead of eyes as the receiver to measure the focal length of lens in this paper. Based on the theory of point spread function, it firstly determined the evaluation function of focal plane. With the threshold method, it determined the location coordinate of sharp signal. Then it proved the feasibility of this scheme through experiment. Finally we compared the experimental data obtained with this method with the experimental data obtained with traditional method, which showed that it was more accurate to measure the focal length of lens with this method.

基于机器视觉的输送带图像在线采集技术的研究

由于基于机器视觉输送带检测中输送带运动速度快、上下输送带间隔距离近(物距小)、采集范围大(视场大)，造成图像信息采集困难。本文提出了利用单个线阵CCD相机输送带图像的采集方法，该方法采集图像的视场角大，每个采集点只需要一个相机，网络传输方便，对网络传输要求低，图像处理简单，易于实现；利用工程光学理论，设计了单个相机的输送带图像在线采集系统，并对照明系统进行了设计。在实验室搭建了基于机器视觉的单个线阵CCD相机的输送带图像采集系统，进行了实验研究，结果表明该系统可实现高质量的输送带图像的采集，为研制基于机器视觉的输送带在线监测系统提供了基础。 Mine conveyor belt has problems of fast speed, short distance and large field of view, and it is difficult to collect image information. Focusing on these problems, this paper proposes a method of using a single linear array CCD camera to collect the image of conveyor belt. When using this method, the field angle of the image capturing is large and each collection point only needs one camera. So that the transmission system is to facilitate the network, the network transmission requirements are low, and the image processing is simple and easy to implement. Under the theory of optical engineering, scheme of collecting the whole image of the conveyor belt by using a single linear array CCD camera was provided and the lighting system was specially designed. Belt image acquisition system on a conveyor belt was built in the laboratory and a large number of experiments were carried out. The experiments show that this system can collect high quality conveyor belt image information, and also can provide foundation for the development of the on-line image acquisition system of conveyor belt based on machine vision.

Spectral domain optical coherence tomography for embryo heart flow measurement

The measurement of blood-plasma velocity distributions with high spatial and temporal resolution in vivo is important for the investigation of embryonic heart at its early stage development. Optical Coherence Tomography is a non-invasive imaging modality with high resolution (5 to 20μm) that can provide flow velocity information by calculating the Doppler frequency shift. In this paper, a high speed spectral optical coherence tomography system was demonstrated. An achievable scanning speed of 92k line/sec has been reached by using an ultra-high speed linear array CCD camera. The measurable flow velocity range is [-24,24]mm/s using this system. Early stage Chicken embryo heart blood flow was measured in vivo.

Micromechanical behavior of cortical bone as inferred from laser speckle data.

We investigated the micromechanical behavior of porcine femoral cortical bone using a novel, nondestructive, noncontacting, laser-based strain measurement technique. The technique is based upon the well-known concept of tracking translating laser speckle with a linear array CCD camera, but employs a unique data-processing scheme based upon a two-dimensional frequency transform of the data. The method proved to be successful in evaluating strain rates in the bone samples. Measured strain rates ranged between 4.61 and 23.84 micro epsilon/s. Total strains recorded were between 3.7 and 19.1 micro epsilon. Estimated Young's moduli averaged 9.01 +/- 3.93 GPa, which, considering the extremely slow strain rates, is an acceptable value for porcine cortical bone. General advantages of the technique include high sensitivity, insensitivity to zero-mean noise sources, compact design, and the fact that it is truly noncontact. A brief discussion of possible error sources within the method is also given.