Measurement error analysis and accuracy enhancement of 2D vision system for robotic drilling

Robotic drilling for aircraft structures demands higher accuracy on industrial robots than their traditional applications. Positioning error measurement and compensation based on 2D vision system is a cost-effective way to improve the positioning accuracy in robotic drilling. In this paper, we first discuss the principle of error measurement and compensation with a 2D vision system for robotic drilling and the determination of tool center point of the vision system so that the Abbe errors are eliminated in the measurement process. Measurement errors due to nonideal measurement conditions, i.e. nonperpendicularity of the camera optical axis to the workpiece surface and incorrect object distance, are mathematically modeled and experimentally verified. A method utilizing four laser displacement sensors is proposed to ensure perpendicularity of the camera optical axis to the workpiece surface and correct object distance in the measurement process, and hence to achieve high accuracy in 2D vision-based measurement. Experiments performed on a robotic drilling system show that the 2D vision system can achieve an accuracy of approximately 0.1 mm with the proposed method.     

Machine vision based path planning for a robotic golf club head welding system

A path planning method based on machine vision techniques is constructed for a golf-club head robotic welding system. This system uses 3D machine vision techniques to recognize the weldseam and generates a welding path for the robot. The location of the weldseam is discovered by applying a Sobel mask to the captured data. A Laplace mask is also useful to filter out the noise points due to the scatter light refraction of tack-welding spots. The weldseam is then replenished and smoothed out by a B-spline curve fitting. The task frame of the weldseam is computed by finding the tangent, normal, and bi-normal of the curve. The robotic welding path is obtained by further rotations and translation along the axes of the task frame according to the requirement of the welding attitude. The developed machine vision technique and the mathematic framework pertaining to the generation of a welding task frame can readily be used for various three-dimensional welding tasks.     

扶正器测试系统研究与实现

根据扶正器结构与测量需求,设计实现了扶正器综合测试系统.系统综合利用了管道压力、光电和应变测量等多种手段,完成了扶正器在旋转过程中的推力、转速、推出偏差角的测量,从而为扶正器的检验与校正提供了有力手段.     

Maintaining a common co-ordinate system for a group of robots based on vision

This work presents a novel approach to the problem of establishing and maintaining a common co-ordinate system for a group of robots. A camera system mounted on top of a robot and vision algorithms are used to calculate the relative position of each surrounding robot. The watched movement of each robot is compared to the reported movement which is sent over some communication link. From this comparison a co-ordinate transformation is calculated. The algorithm was tested in simulation and is at the moment being implemented on a real robot system. Preliminary results of real world experiments are being presented.     

A robust navigation system for robotic wheelchairs

A landmark based navigation system for robotic wheelchairs is developed. The proposed navigation system is robust in the localization procedure which is the major problem in robotic navigation systems. Every landmark is composed of a segment of metallic path and a radio-frequency identification (RFID) tag. The odometry information is used for localization, which is corrected on-line every time the robotic wheelchair is over a landmark. A topological map is generated using such landmarks to compute the shortest path. A technique to generate the topological map for this navigation system and an obstacle avoidance strategy are also developed.     

Development of CAM system based on industrial robotic servo controller without using robot language

This paper describes the development of a robotic CAM system for an articulated industrial robot RV1A from the view point of robotic servo controller. It is defined here that the CAM system includes an important function which allows an industrial robot to move along cutter location data (CL data) consisting of position and orientation components. In addition, the developed CAM system has a high applicability to other industrial robots whose servo systems are technically opened to end-users. The developed robotic CAM system works as a straightforward interface between a general CAD/CAM and an industrial robot. At the present stage, the relationship between CAD/CAM and industrial robots is not well established compared to NC machine tools that are widely spread in manufacturing industries. The CAM systems for NC machine tools are already established, however, the CAM system for industrial robots has not been sufficiently considered and developed yet. A teaching pendant is generally used to obtain position and orientation data of the arm tip before an industrial robot works. Here, in order to enhance the relationship between a conventional CAD/CAM system and an industrial robot, a simple and straightforward CAM system without using any robot language is developed and implemented. The basic design of the robotic CAM system and the experimental results are presented in this paper.     

Evolution of a vision system by genetic algorithm

This paper proposes a framework for a genetic algorithm applied to determine and construct an organ, especially the neural network of a virtual creature. The vision system of the creature is a result of genetic evolution, and we are trying to realize this on the computer. We examine how the visual organ of the animal is evolved under a special environment (e.g., the specialized visual organ of an animal to catch a moving insect), and how many variations of neural networks exist. We also think it is possible to generalize the method to an automatic generation of various kinds of visual recognition system by adding various kinds of evolution any directions. This work was presented, in part, at the Second International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1997     

PD with sliding mode control for trajectory tracking of robotic system

Good tracking performance is very important for trajectory tracking control of robotic systems. In this paper, a new model-free control law, called PD with sliding mode control law or PD–SMC in short, is proposed for trajectory tracking control of multi-degree-of-freedom linear translational robotic systems. The new control law takes the advantages of the simplicity and easy design of PD control and the robustness of SMC to model uncertainty and parameter fluctuation, and avoid the requirements for known knowledge of the system dynamics associated with SMC. The proposed control has the features of linear control provided by PD control and nonlinear control contributed by SMC. In the proposed PD–SMC, PD control is used to stabilize the controlled system, while SMC is used to compensate the disturbance and uncertainty and reduce tracking errors dramatically. The stability analysis is conducted for the proposed PD–SMC law, and some guidelines for the selection of control parameters for PD–SMC are provided. Simulation results prove the effectiveness and robustness of the proposed PD–SMC. It is also shown that PD–SMC can achieve very good tracking performances compared to PD control under the uncertainties and varying load conditions.     

互感器检定仿真实训软件系统的设计与实现

现有互感器检定培训模式均采用实际操作的方式,存在周期长、工作效率低、有安全隐患等问题,本文开发了一套仿真培训软件系统,该系统集培训、仿真和实训为一体,学员可利用系统进行培训、考试、仿真接线和设备认知,通过系统性的学习和训练,最终掌握互感器检定技术。     

Automatic folding of cartons using a reconfigurable robotic system

This paper proposes new theories and methodology for the study of folding carton and reconfigurable packaging systems and presents both virtual and experimental systems to support the theories. Equivalent mechanisms of cartons were established by describing carton creases as joints and carton panels as links. With the analysis of the equivalent mechanism, the gusset vertexes of cartons were analyzed based on their equivalent spherical linkages and were identified as guiding linkages that determine folding. A reconfigurable robotic system was developed to demonstrate the ability to erect diverted cartons in the reconfigurable packaging system which could previously only be achieved manually.     

A machine vision system for measuring wear and chipping of drilling tools

An automated measurement system for detection of drilling tool malfunctions such as wear and chipping has been developed for application to machining centres. A machine vision system with two industrial television cameras has been developed. A global image provided by the first camera is used to rotate the drill such that a major cutting edge is a central vertical line in each of the detailed images provided by the second camera. The second camera, with an autofocusing mechanism, focuses towards a potentially affected small region of the drill. Three detailed images are used for detection of drilling tool malfunctions, and failed portions are extracted using image-processing techniques. Three-dimensional surface contours of the failed portions along with one- and two-dimensional quantities such as wear width, chipping width, and the failed portion area are measured. Lighting directions are determined so that the diffusion component dominates specular reflection, and the failed portions are illuminated more than the normal portions.     

Development of a system for robotic deburring

Relatively crude robotic deburring has been accomplished through the detailed programming of the edge contour and the provision of significant passive compliance to compensate for positional errors. In precision deburring, the uncertainties in edge position relative to the tool location may be too great to allow a sufficiently uniform chamfer to be obtained using passive compliance alone. In addition, the costs associated with the detailed path programming can represent a significant fraction of the cost of deburring. This paper discusses the development of a robotic deburring system which provides for simultaneous edge following and force control. An AdeptOne robotic manipulator has been interfaced with an instrumented remote center of compliance manipulator to provide a system which tracks an edge at a controlled force level which can be specified by the operator.     

单目视觉在棒料全自动上下料系统中的应用

在全自动上下料系统中,机器视觉技术以它快而准确无误的性质发挥重要的作用.针对系统的功能要求,进行了基于单目视觉全自动上下料系统平台的设计和搭建,通过Halcon完成了摄像机和机械手标定,理论上研究了实现空间棒料的三维姿态的算法,在图像处理中运用二项式滤波、傅立叶变换、闵可夫斯基加减法确定空间棒料的三维姿态,通过VS2015C#与Halcon混合编程,进行软件界面开发,控制机械手上下料.结果表明该方法具有可行性.     

Development and characterization of a multi-camera 2D-vision system for enhanced performance of a drink serving robotic cell

A 2D-vision system is integrated into a drink-serving robotic cell, to enhance its flexibility. Two videocameras are used in a hybrid configuration scheme. The former is rigidly mounted on the robot end effector, the latter is fixed to the workplace. The robot cell is based on two Denso robots that interoperate to simulate real human tasks. Blob analysis, template matching and edge detection algorithms cooperate with motion procedures for fast object recognition and flexible adaptation to the environment. The paper details the system workflow, with particular emphasis to the vision procedures. The experimental results show their performance in terms of flexibility and robustness against defocusing, lighting conditions and noise.     

Control of a robotic orthosis for gait rehabilitation

Robot assisted gait training may help in producing rapid improvements in functional gait parameters. This paper presents new experimental results with an intrinsically compliant robotic gait training orthosis. The newly developed robotic orthosis has 6 degrees of freedom (DOFs). A trajectory tracking controller based on the boundary layer augmented sliding control (BASMC) law was implemented to guide the subject’s limbs on physiological gait trajectories. The compliance of the robotic orthosis sagittal plane hip and knee joints was also controlled, independently of the trajectory tracking control. The robotic orthosis and the control scheme were evaluated on three neurologically intact subjects walking on a treadmill. A maximum trajectory tracking error of 10° was recorded at the hip and knee sagittal plane joints. The results showed that subjects can walk in the robotic orthosis with comfort and the BASMC law was able to guide the subject’s limbs on reference physiological trajectories.     

井下仰角钻孔测井系统设计

针对传统的测井系统存在总线利用率低、数据传输速率低等问题,提出了一种井下仰角钻孔测井系统设计方案,着重论述了系统结构、网络拓扑和以PIC18LF4680为核心的探管节点的软硬件设计。该系统应用文件管理控制芯片管理系统数据,实现了有缆和无缆2种测井方式。实际应用表明,该系统运行稳定,适用于生产矿井工况的测量。     

Development of a knowledge-based self-assessment system for measuring organisational performance

Effective performance measurement is an important task in the discipline of engineering management. With the support of City University of Hong Kong, a research project was initiated to develop a knowledge-based expert self-assessment (KES) training toolkit on measuring and assessing organisational performance based on the evaluation criteria of a renowned Business Excellence Model—the Malcolm Baldrige National Quality Award (MBNQA). This paper explains the development of and elaborates the system framework, requirements, design and validation of the toolkit. The project results shows that the toolkit could facilitate the teaching of students of engineering management courses by providing a stimulating learning environment and practical experiences in measuring and assessing enterprise performance. Incorporating the KES model and toolkit into the engineering management curriculum can provide students and industrial users with hands-on experience and insights of organisational PM.     

小型无人直升机着陆高度单目视觉测量方法

针对小型无人直升机自主降落过程中姿态发生变化和非差分GPS高程精度不高的情况,研究了一种基于单目视觉的小型无人直升机离地高度测量方法,用于提高自主降落的品质。在机体姿态角已知的情况下,识别提取降落图标中相互平行的特征直线段,并根据机载摄像头投影模型,实时求解机体降落过程中的离地高度。在测量系统上进行了实体实验,验证了所提出的方法,实验结果表明:该方法特征识别率高,在机体平面与地面存在倾角时,输出结果的实时性与准确性亦均能满足小型无人直升机自主降落要求。     

A monocular vision system for online pose measurement of a 3RRR planar parallel manipulator

In this paper, we develop a monocular vision system for online pose measurement of a 3-RRR planar parallel manipulator (PPM). By combining with a camera with global shutter, an active marker array, an industrial personal computer, and a degenerated perspective-n-points (DPnP) algorithm, a monocular vision measurement system (MVMS) is established. To improve measuring accuracy of the MVMS, factors that cause inaccuracy including the lens distortion, non-perpendicular angle, and input parameters’ uncertainty are analyzed and modeled in detail. In the simulation, effects of these error factors on the accuracy of the MVMS are quantitatively displayed, and comparisons between the DPnP algorithms and other state-of-art PnP algorithms are conducted. Experimental tests on the constructed MVMS demonstrate that it not only can accurately and efficiently measure pose of the 3RRR PPM, but possesses a higher operability and stability compared to the laser tracker.     

Development of a mobile robotic system for working in the double-hulled structure of a ship

Shipbuilding processes involve highly dangerous manual welding operations. Welding ship walls inside double-hulled structures presents a particularly hazardous environment for workers. This paper describes the “Rail Runner X” (RRX), a new robotic system that can move autonomously inside the walls of a double-hulled ship and automatically execute the required welding processes. The RRX robotic system is composed of a mobile platform and a welding robot consisting of a 3P3R serial manipulator. The robot is used to weld U-shaped trajectories located between two longitudinal stiffeners. The mobile platform enables traverse movements onto neighboring longitudinal stiffeners. The entire cross section of the robotic system is small enough to be placed inside the double-hulled structure via a conventional access hole from the outside shipyard floor. The overall engineering design process that led to the final robot solution developed is presented in this paper, including kinematic analysis data and experimental results for verifying the autonomous movement and welding performance.