Calibration of line structured light vision system based on camera’s projective center

Based on the characteristics of line structured light sensor, a speedy method for the calibration was established. With the coplanar reference target, the spacial pose between camera and optical plane can be calibrated by using of the camera’s projective center and the light’s information in the camera’s image surface. Without striction to the movement of the coplanar reference target and assistant adjustment equipment, this calibration method can be implemented. This method has been used and decreased the cost of calibration equipment, simplified the calibration procedure, improved calibration efficiency. Using experiment, the sensor can attain relative accuracy about 0.5%, which indicates the rationality and effectivity of this method.

Hybrid Visual Servoing Control for Robotic Arc Welding Based on Structured Light Vision

A novel hybrid visual servoing control method based on structured light vision is pro-posed for robotic arc welding with a general six degrees of freedom robot. It consists of a positioncontrol inner-loop in Cartesian space and two outer-loops. One is position-based visual control inCartesian space for moving in the direction of weld seam, i.e., weld seam tracking, another is image-based visual control in image space for adjustment to eliminate the errors in the process of tracking.A new Jacobian matrix from image space of the feature point on structured light stripe to Cartesianspace is provided for dierential movement of the end-e?ector. The control system model is simplifiedand its stability is discussed. An experiment of arc welding protected by gas CO2 for verifying iswell conducted.

Seam Tracking and Visual Control for Robotic Arc Welding Based on Structured Light Stereovision

A real-time arc welding robot visual control system based on a local network with a multi-level hierarchy is developed in this paper. It consists of an intelligence and human-machine interface level, a motion planning level, a motion control level and a servo control level. The last three levels form a local real-time open robot controller, which realizes motion planning and motion control of a robot. A camera calibration method based on the relative movement of the end-effector connected to a robot is proposed and a method for tracking weld seam based on the structured light stereovision is provided. Combining the parameters of the cameras and laser plane, three groups of position values in Cartesian space are obtained for each feature point in a stripe projected on the weld seam. The accurate three-dimensional position of the edge points in the weld seam can be calculated from the obtained parameters with an information fusion algorithm. By calculating the weld seam parameter from position and image data, the movement parameters of the robot used for tracking can be determined. A swing welding experiment of type V groove weld is successfully conducted, the results of which show that the system has high resolution seam tracking in real-time, and works stably and efficiently.

Effect of corneal light scatter on vision: a review of the literature

The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to provide rigidity to the entire eyeball.Therefore,good vision requires maintenance of the transparency and proper refractive shape of the cornea.The surface structures irregularities can be associated with wavefront aberrations and scattering errors.Light scattering in the human cornea causes a reduction of visual quality.In fact,the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye.In most cases,a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering.In fact,clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades.The measurement of corneal back scattering qualifies the degree of corneal transparency.The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency.The aim of this study was to review scattering in the human cornea and methods of measuring it.

Structured Light 3D Vision Based on Laser Scanning Space-encoding and Its Synchro Control

This paper presents the principle and mathematic model for the 3D depth map method based on space encoding images performed by modulating scanning structuredlight according to time sequences,and the synchro control among the camera,laser diode modulation and scanning polyhedron.

Developing a Machine Vision System Equipped with UV Light to Predict Fish Freshness Based on Fish-Surface Color

This study assessed the feasibility of developing a machine vision system equipped with ultraviolet (UV) light, using changes in fish-surface color to predict aerobic plate count (APC, a standard freshness indicator) during storage. The APC values were tested and images of the fish surface were taken when fish were stored at room temperature. Then, images’ color-space conversion among RGB, HSV, and L*a*b* color spaces was carried out and analyzed. The results revealed that a* and b* values from the UV-light image decreased linearly during storage. A further regression analysis of these two parameters with APC value demonstrated a good exponential relationship between the a* value and the APC value (R2 = 0.97), followed by the b* (R2 = 0.85). Therefore, our results suggest that the change in color of the fish surface under UV light can be used to assess fish freshness during storage.

夜间动物目标的被动式快速监测方法

针对夜间暗环境下夜行动物目标监测所面临的照度低、对光线敏感和目标活动易产生拖影等问题,研究夜间暗环境动物目标的被动式快速监测方法。利用被动式微光夜视相机对动物目标进行成像监测,避免补光对夜行动物产生惊扰;利用短曝光和低光增强算法Zero-Denoise解决运动物体拖影和图像亮度低的问题,进而对增强后的图像进行目标识别和跟踪。实验结果显示,Zero-Denoise网络能有效提升夜间动物图像观测的质量,在给定试验条件下使目标检测算法精度提升6.8%,速度达到32 f/s。因此,这种结合微光夜视相机与低光增强算法Zero-Denoise的监测方法,适用于夜间暗环境动物目标的被动式快速监测。

空间定位与特征泛化增强的铁路异物跟踪检测

针对现有深度学习异物跟踪检测算法易受复杂环境、目标遮挡等影响,导致出现漏检及检测精度低等问题,提出了一种空间定位与特征泛化增强的铁路异物跟踪检测算法。提出改进多尺度级联GhostNet特征提取网络,提升对红外目标的特征提取能力;利用异物空间位置定位与泛化形态信息,设计空间定位与特征泛化增强模块,增强对复杂场景下位置移动与跟踪轨迹变化目标的检测精度;构建金字塔预测网络,得到红外铁路异物的检测锚框、类别及置信度信息;通过改进类别和置信度显示的DeepSORT跟踪算法,结合卡尔曼滤波与匈牙利算法实现红外弱光环境下铁路异物跟踪检测。实验结果表明:所提算法对铁路异物的跟踪检测精确度达到83.3%,平均检测速度为11.3帧/s;与比较算法相比,所提算法检测精度更高,对红外弱光场景下铁路异物跟踪检测具有较好的性能。

基于双目视觉和改进YOLOv8n的火灾检测及测距方法

针对火灾检测出现的漏检误检、模型参数量大及定位困难的问题,基于双目视觉和改进YOLOv8n提出了一种轻量化火灾检测及测距方法.通过双目相机拍摄图片,使用改进的检测算法YOLOv8n-AEM和现有的测距算法SGBM进行检测和测距.首先,在主干网络中引入可变核卷积AKConv和EMA注意力机制,通过构建不规则卷积核有效提取火灾的特征;然后,在颈部网络中构建C2f-SCConv模块,通过特征重组降低模型参数,提高检测速度;其次,基于最小点距离改进损失函数,解决火源与光源重叠导致的漏检与误检问题;最后,增加小目标检测头,提高对小火苗的检测能力.实验结果表明,改进后的检测算法P、R、mAP分别为83.6%、76.4%、83.6%,分别提高了2.5%、3.6%、4.8%;参数量和模型大小分别为2.54 M和5.1 MB,分别降低了15.3%和15%;测距精度误差不超过2.5%,证明改进的方法能准确完成火灾的检测及测距.

面向低光照环境的车辆目标检测方法

在智慧交通系统和城市安全领域中,准确获取车辆信息至关重要.通过视频或图像等视觉识别手段可以直接获取车辆相关信息.然而,在低光照环境下,图像亮度和对比度降低、噪声增加、图像细节特征易丢失,这些问题导致车辆目标检测算法的精度大大降低.为此,提出了一种基于低光照图像增强算法和改进目标检测算法的车辆检测方法.首先,利用图像增强算法ZeroDCE对低光照图像进行增强,以提升图像亮度;然后,利用改进的AFF-YOLO目标检测网络对增强后的图像进行车辆检测;最后,将本文方法在车辆数据集上进行测试,并分析不同低光照等级对于车辆检测精度的影响.结果表明,本文方法能够有效提升车辆目标检测的精度,与低光照图像相比,增强后图像的目标检测精度mAP@0.5提升了4.9%,达到94.7%;而且光照强度越低,增强后图像的目标检测精度提升越显著.研究成果可为低照度环境下的车辆检测提供参考.

基于YOLOv5的焊缝图像特征信息检测方法研究

为了满足自动化工艺的需要和获取更为清晰的焊缝原始图像,提出了一种基于YOLOv5和结构光的焊缝特征点提取算法。首先利用激光视觉系统获取焊缝图像,使用改进后的YOLOv5算法进行预训练;然后通过Steger算法提取结构光中心线,使用Harris算法对中心线图像进行处理,并确定焊缝坐标点的坐标;最后将坐标信息传输给PLC,控制十字滑台带动焊枪进行焊缝的跟踪操作。实验结果表明,改进后的YOLOv5算法mAP值更大、稳定性更高、鲁棒性更强。

Research on Night Vision System Based on Range-Gated Imaging

A design of low-light-level night vision system is described,which can image objects selectively in the specific space. The system can selectively image some objects in specific distances,meanwhile ignore those shelters on the way of observation by combining an intensifying charge coupled device(ICCD) with a near infrared laser assisted in vision,whose operation wavelength matches with the photocathode of the image tube,and adopting the gated mode and adjustable time-delay. A semiconductor laser diode of 100 W in peak power is chosen for illumination. The laser and the image tube operate in 150 ns pulse width and 2 kHz repeat frequency. Some images of different objects at the different distances within 100 m can be obtained clearly,and even behind a grove by using a sampling circuit and a delay control device at 100 W in peak power of semiconductor laser diode,150 ns in pulse width of laser and image tube,2 kHz in repeat frequency.

Accurate Measurement Method for Tube's Endpoints Based on Machine Vision

Tubes are used widely in aerospace vehicles, and their accurate assembly can directly affect the assembling reliability and the quality of products. It is important to measure the processed tube＇s endpoints and then fix any geometric errors correspondingly. However, the traditional tube inspection method is time-consuming and complex operations. Therefore, a new measurement method for a tube＇s endpoints based on machine vision is proposed. First, reflected light on tube＇s surface can be removed by using photometric linearization. Then, based on the optimization model for the tube＇s endpoint measurements and the principle of stereo matching, the global coordinates and the relative distance of the tube＇s endpoint are obtained. To confirm the feasibility, ll tubes are processed to remove the reflected light and then the endpoint＇s positions of tubes are measured. The experiment results show that the measurement repeatability accuracy is 0.167 mm, and the absolute accuracy is 0.328 ram. The measurement takes less than 1 min. The proposed method based on machine vision can measure the tube＇s endpoints without any surface treatment or any tools and can realize on line measurement.

Does Light Exposure during Embryonic Development Affect Cognitive Behavior in a Lizard?

Light is essential for embryonic development in many ovipa rous animals including fish,amphibians,and birds.However,light may be harmful for reptile embryos developing underground where they are in complete darkness and beneath thin eggshells.Nonetheless,how embryonic light conditions affect reptile development and offspring remains largely unknown.Here we incubated eggs in dark and light conditions to determine the effects of light exposure on embryonic development and offspring visual ability,spa tial cognitive ability and growth in a lacertid lizard,Eremias argus.Our experiments demonstrated that light stimulation shortened incubation duration of eggs,but did not affect hatching success,offspring size,visual ability or survival More interestingly,light exposure during incuba tion decreased spa tial cognitive ability and post-hatching growth of offspring On the basis of nega tive effects on offspring growth rates,our study indicates that in squamate reptiles with thin eggshells,light exposure in early development has negative effects on offspring cognitive ability.

基于线结构光扫描的烟支表面缺陷检测方法研究

在烟支表面缺陷检测时,为解决传统二维图像方法无法获得深度信息的问题,提出一种基于线结构光传感器旋转扫描的检测方法。烟支在两同向辊轮的旋转带动下实现自转,通过线结构光视觉传感器获取物体轴向轮廓线,使用随机采样一致性拟合轮廓线,通过计算原始点到拟合轮廓的距离判断缺陷点。选取某品牌烟支在检测过程中得到的原始数据,其中多组样本的Kappa值均达到0.97,重复性达到99.3%。研究为烟支缺陷检测提供参考。

Quantum and Non-Quantum Formulation of Eye’s Adaptation to Light’s Intensity Increments

Context and background: A quantum formulation of vision in vertebrates was proposed in the early 1940s. The number of quanta useful for enabling vision was found. The time interval required for their absorption, however, was never specified. In the early 1950s, experimental data on the effects of light’s intensity increment on vision indicated that the quantum formulation is true only at low light’s intensities. In this case, a vaguely described signaling adaptation mechanism was invoked to explain the separation between vision at low and high intensities, accompanied by the switch from rod to cones as photoreceptors. Motivation: In this article, we want to prove the validity of the non-totally-quantum formulation and unveil the nature of the signaling adaptation mechanism. Hypothesis: To accomplish our proof, we hypothesize that the amount of energy transferred and conserved in light’s interaction with the eyes is given by the product of light’s intensity (or power) times its period. Method: We construct and use the plots of the trends of light’s intensity increments and the corresponding changes in the axon’s membrane capacitance versus adapting intensity. Results: We find that 1) the average solar light’s intensity is the critical value that separates low from high light’s intensity regimes in vision, and 2) changes in the capacitance of the axon’s membrane enable the signaling adaptation of vision when light’s intensity changes. Conclusions: We prove the validity of the non-totally-quantum formulation and unveil the nature of the signaling adaptation mechanism. Our proof is supported by the model based on light’s intensity times period as being the energy conserved in light-matter interaction This model suggests that 1) all the waves in the electromagnetic spectrum, at the correct intensity for each frequency, could be used to produce the effects of optogenetics in diagnostics and therapy, and 2) it takes seconds to minutes to see details in the dark when light is switched off.

基于机器视觉的飞机电镀部件曲表面无损检测

[目的]为解决机器视觉在曲表面无损检测中算法复杂的问题,以及克服传统光源在曲表面检测中的局限性,开发了一套基于格栅光源的飞机电镀部件曲表面无损检测系统。[方法]该系统通过格栅光对电镀部件曲表面进行成像,随后进行图像分析,包括图像导入、预处理、Blob分析等步骤。[结果]该系统能够快速、准确地检测出电镀部件曲表面存在的缺陷,检测效率高且稳定可靠。[结论]该系统在飞机制造企业及航空公司飞机维护一线的初步工程应用中取得了良好效果,有望进一步推广。

Modeling of a Linear Scanning 3D Vision Coordinate Measurement System

This paper theoretically analyzes and researches the coordinate frames of a 3D vision scanning system, establishes the mathematic model of a system scanning process, derives the relationship between the general non-orthonormal sensor coordinate system and the machine coordinate system and the coordinate transformation matrix of the extrinsic calibration for the system.

一种面向机器视觉感知的暗光图像增强网络

低光照等恶劣环境下的目标检测一直都是难点,低光照和多雾因素往往会导致图像出现可视度低、噪声大等情况,严重干扰目标检测的检测精度。针对上述问题,提出了一个面向机器视觉感知的低光图像增强网络MVP-Net,并与YOLOv3目标检测网络整合,构建了端到端的增强检测框架MVP-YOLO。MVP-Net采用了逆映射网络技术,将常规RGB图像转换为伪RAW图像特征空间,并提出了伪ISP增强网络DOISP进行图像增强。MVP-Net旨在发挥RAW图像在目标检测中的潜在优势,同时克服其在直接应用时所面临的限制。模型在多个真实场景暗光数据上取得了优于先前工作效果并且能够适应多种不同架构的检测器。其端到端检测框mAP(50%)指标达到了78.3%,比YOLO检测器提高了1.85%。

基于线结构光的厚板焊缝特征点提取算法

针对厚板结构件在使用激光视觉系统时图像特征区域提取难和工件表面加工不均匀漫反射等导致特征点提取困难的问题,提出基于线结构光的厚板焊缝特征点提取算法。首先,激光视觉系统获取焊缝图像并使用YOLOv4算法进行预训练,利用训练获取的权重文件自动检测并获取焊缝特征感兴趣区域(ROI);其次,对ROI进行降噪、二值化等处理,通过逐行(列)搜索法得到焊缝中心线;最后,根据不同焊缝类型,基于最小二乘法使用距离法和直线段聚类的方法来提取特征点。实验结果表明:该方法可有效提取不同类型的焊缝特征点,具有鲁棒性强、识别误差小等特点。