In the present study, we used computational fluid dynamics to analyze the sag caused by spray painting, considering the change in paint shape due to flow. We focused on the paint adhering to the ...target surface because this behavior has not been previously examined. The particle method was adopted for the calculation because it enabled a stable analysis of the paint droplets and the complex uneven surface of the paint film. A high-speed camera and image analysis were used to capture the spray painting and identify the parameter values. Using the developed model, we analyzed the change in the film thickness distribution for painting on a flat plate in the vertical direction. It was confirmed that the numerical and experimental data correlated for two conditions of the target distance. In addition, we proposed a new index, Degree of Sagging (DSG), to evaluate the amount of sag based on the physical properties of the paint rheology and the geometry of the target. In the painting tests on flat plates with different angles, a strong positive correlation of 0.95 was observed between the sum of the calculated DSG values and the measured paint flow distance due to sag. In the painting tests on L-shaped surfaces, the predicted sag appearance by DSG agreed with the measured results at 14 of the 15 measurement points under all conditions. Overall, a computational model was developed for field implementation that could predict painting thickness distribution and sag occurrence. Note to Practitioners -The present work is motivated by the problem that teaching painting robots in a painting site is particularly time consuming. To address this problem, off-line programming methods have been proposed to computationally predict paint quality and film thickness and determine the painting route. Conventional approaches have approximated the paint deposition model with a function, which determines the paint thickness distribution, or simulated this model with high accuracy by considering electrostatic forces and wind velocity fields using computational fluid dynamics (CFD) modeling methods. However, two major problems exist in the field implementation of these studies: The first problem is the inability to predict defects, including sagging, that may occur after painting. In the conventional approach, the behavior of the paint after it adheres to the target is outside the scope of the calculation. The second problem is the high computational resource cost of CFD simulation, which renders its application to robotic painting challenging. In painting sites, the painting thickness must be accurately predicted and routed in a short period of time. In this paper, we present a method for analyzing film thickness distributions by considering time series changes of flow and propose a function-based model for predicting sagging based on the simulation results. The model for sag prediction was shown to be computationally inexpensive enough to be implemented in the field. The results of several painting experiments with a real robot confirmed the validity of the predictions made by this method. Our method could be implemented in the near future as a prediction system for off-line evaluation of painting routes, which could significantly reduce teaching cost. Since the target in this paper was a flat plate, it is necessary to conduct evaluation tests using various target shapes and painting conditions. Also, integration with the painting route optimization method has not yet been achieved, which is a topic that will be addressed in the future.
This paper focuses on intuitive and direct off-line robot programming from a CAD drawing running on a common 3-D CAD package. It explores the most suitable way to represent robot motion in a CAD ...drawing, how to automatically extract such motion data from the drawing, make the mapping of data from the virtual (CAD model) to the real environment and the process of automatic generation of robot paths/programs. In summary, this study aims to present a novel CAD-based robot programming system accessible to anyone with basic knowledge of CAD and robotics. Experiments on different manipulation tasks show the effectiveness and versatility of the proposed approach.
•A novel CAD-based off-line robot programming solution.•Robot programs are automatically generated from a CAD drawing.•Robot cell design and robot programming are embedded in the same interface.•The system is intuitive to use and presents a short learning curve.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
As a key technology of robotic assembly system, off-line programming (OLP) is an effective way to improve processing quality and efficiency. Currently, the basic functions of OLP systems, such as ...trajectory planning, three-dimensional task simulation and collision detection, could not achieve high machining precision and guarantee the quality stability. Thus, robot kinematics and stiffness performance optimization need to be investigated as secondary tasks in the special OLP system, on the basis of redundant kinematics characteristic of a serial robot system with external axis. First, a singularity measurement model of robot configuration is presented under the constraint of joint-limits to achieve the avoidance of singular and joint-limits configurations. Secondly, based on the robot static stiffness model, an axial stiffness identification method has been come up with to evaluate the stiffness performance in the processing direction. Next, with the combination of singularity measurement model and axial stiffness identification method, a redundancy resolution method is put forward to plan and optimize the configuration of robot system with external axis off-line, which keeps robots away from singularity and joint-limits, and meanwhile achieve the optimum stiffness during robotic drilling process. Finally, the validity of this method in improving drilling quality and stability is verified by the application in a robotic drilling system.
•Robot kinematics and stiffness performance optimization are investigated as secondary tasks in the specialized OLP system.•A singularity measurement model of robot configuration is presented under the constraint of joint-limits to achieve the avoidance of singular and joint-limits configurations.•An axial stiffness quantitative evaluation method is come up with to evaluate the stiffness performance of robot system with external axis in the processing direction.•With the combination of singularity measurement model and axial stiffness identification method, a redundancy resolution method is put forward to plan and optimize the configuration of robot system with external axis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Recently, the use of industrial robots as an alternative to computer numerical controlled (CNC) workbenches has been increasing due to the lack of access capabilities of CNC, their large masses and ...costs. Computer-aided design (CAD) and computer-aided manufacturing (CAM) programs for industrial robot applications are still limited due to the following reasons. The trajectories in the CNC program are transformed into robot programs. Despite the wide-ranging capabilities of robots, the tooling orientation is not considered and the trajectory information is generated for commonly used blade geometries due to its suitability for CNCs. The robot configuration is not considered. When the industrial robots compared to CNCs, they have some disadvantages due to their articulated structure. They have difficulty in processing hard surfaces. In this study, a CAD program was developed for robotic milling to resolve the above-mentioned basic problems. Also, it can generate trajectories to increase the surface treatment quality. The program creates trajectory for IRBs from the graphic models in 3ds (3D Studio) format. The depth of the surface treatment can be controlled to increase the stiffness and reduce the geometric errors due to the robots are not rigid enough.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
WAAM (Wire + Arc Additive Manufacturing) is an alternative additive technology that combines an electric arc as a heat source, filler material in the form of a wire for welding and cladding ...individual weld passes so as to ultimately achieve the closest shape of produced components. Nowadays, when it is modern to digitize the manufacturing production, this process can also be designed using off-line programming tools and 3D simulations of the robot that welds the whole structure. This study deals with the comparison of three structured continuous welds using different weld metal transfers. From the results of the first two processes (dip transfer and IAC process), optimization was achieved using the CMT process and the welding path correction. As the filler material, the low-alloyed solid wire electrode for shielded arc welding of quenched and tempered fine grained structural steels, Böhler Union X 90 (G 89 6 M Mn4Ni2CrMo) with 1 mm in diameter, was used. Obtained samples were subjected to standard technological tests. The results of these tests are used to determine new parameters to ensure stability of this technology. The experiment confirmed that off-line programming will greatly influence the speed and quality of the welding track programs. The results prove that, by combining off-line welding path optimization with an optimized CMT welding process, we can achieve a stable WAAM process.
Industrial robots are increasingly applied in the automatic die repair welding via the prevalent wire and arc additive manufacturing (WAAM) technology. However, the precise calibration of work ...coordinates is indispensable for the off-line programming of robotic welding paths, which often results in positioning error, path deviation, or even tool collisions. The die is pre-heated at about 500 °C before the robotic WAAM processes. Thus, it is challenging to calibrate work coordinates by touch sensing because those points on the
X
-axis and the
Y
-axis to determine the location of the part need to be caught by human eyes. In this paper, a camera vision calibration (CVC) method based on stereo vision is developed. Image feature points are extracted by a multi-saliency fusion algorithm based on the human visual attention mechanism. Through stereo vision, 3D information of the feature points is obtained, and the workpiece coordinate system (WCS) is finely calibrated. Compared with the random error of human vision calibration (HVC), the proposed method could improve the workpiece’s calibration accuracy, reduce the unexpected collisions in limited space, and improve the dimensional precision of the welding layer.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An articulated robot cooperated with a positioner is widely used in the field of intersecting pipes welding. In order to resolve the bottlenecks in productivity caused by the burdensome manual ...teaching process, this article presents an algorithm to generate motion codes for industrial robot to weld intersecting pipes. A unique welding scheme that simplifies welding technology complexity is introduced and adopted. Based on the geometrical model of intersecting pipes with the most complex intersecting mode, the welding trajectory planning is developed which contains posture planning of the welding torch and weaving welding control strategy. Then the welding trajectory is decomposed into the motion of the robot torch and the positioner, and the spatial relationship between the torch and the robot base is described with homogeneous transformation matrix. Finally, an algorithm flow chart with welding speed control strategy is provided for generating robot motion codes. Simulation and welding experiment verify the feasibility of the algorithm.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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