Pose Of Torch Research Articles

Passive Vision Detection of Torch Pose in Swing Arc Narrow Gap Welding.

To enhance the synchronous detection of the horizontal and vertical positions of the torch in swing arc narrow gap welding, a torch pose detection (TPD) method is proposed. This approach utilizes passive visual sensing to capture images of the arc on the groove sidewall, using advanced image processing methods to extract and fit the arc contour. The coordinates of the arc contour center point and the highest point are determined through the arc contour fitting line. The torch center position is calculated from the average horizontal coordinates of the arc contour centers in adjacent welding images, while the height position is determined from the vertical coordinate of the arc's highest point. Experimental validation in both variable and constant groove welding conditions demonstrated the TPD method's accuracy within 0.32 mm for detecting the torch center position. This method eliminates the need to construct the wire centerline, which was a requirement in previous approaches, thereby reducing the impact of wire straightness on detection accuracy. The proposed TPD method successfully achieves simultaneous detection of the torch center and height positions, laying the foundation for intelligent detection and adaptive control in swing arc narrow gap welding.

A novel model-based welding trajectory planning method for identical structural workpieces

Welding robots have been widely used with the development of manufacturing industry. At present, welding trajectory planning and programming of welding robots are performed separately for similar (structural) workpieces with different dimensions or deformations. Besides, the welding torch pose planning using conventional robot programming methods is time-consuming for workpieces with complex welding trajectories. To realize automatic planning of the welding torch pose for similar workpieces and improve the programming efficiency of welding robots, we propose a novel model-based welding trajectory planning method for welding robots. We create a basic model (point set) containing information on welding seam trajectory planning for similar workpieces. The welding seam trajectory extraction of similar workpieces is achieved by the non-rigid point set registration of the feature point cloud of similar workpieces with the basic model. Then, the welding torch pose planning is implemented by the geometric projection method of the local point cloud of the welding seam trajectory. Finally, the results of offline experiments and online experiments demonstrate the effectiveness of the proposed method.

Research on adaptive adjustment of welding torch pose in wire and arc additive remanufacturing of hot-forging dies

Research on adaptive adjustment of welding torch pose in wire and arc additive remanufacturing of hot-forging dies

Integration of a multi-directional wire arc additive manufacturing system with an automated process planning algorithm

With the increasing demand for high productivity and low cost, the advanced manufacturing system has become more complex. It is challenging to develop an advanced manufacturing system by engineers or researchers from manufacturing engineering disciplines. To combine knowledge and skills from two or more disciplines, interdisciplinary engineering (IDE), from industrial information integration, was carried out as a promising subject for further developing advanced manufacturing systems. Recently, Wire arc additive manufacturing (WAAM) technology has attracted attention from industrial sectors due to its capability to fabricate medium-to-large scale components with low capital investment and high productivity. In addition, a variant of WAAM, called multi-directional WAAM techniques, has been developed for the direct fabrication of parts with overhanging features. The multi-directional approach can reduce the need for additional supporting structures, reducing (amongst other things) material costs, manufacturing time, and post-process machining requirements. Although the multi-directional WAAM has a great potential for practical industrial use, the process planning also becomes more complex for developing an automated system for industrial use. This paper presents a novel automated processing planning algorithm and integrates with the automated robot offline programming (AOLP) engine and WAAM hardware. The proposed system aims at planning the multi-directional WAAM process automatically. The process planning algorithm consists of four key modules relating to (a) robot motion planning, (b) initial collision processing, (c) layer sequence optimisation, and (d) weld torch pose adjustment. In the first stage, the required robot motions to deposit each layer are obtained through an AOLP engine. Then a collision matrix is generated to guide later steps of the planning process from these robot motions. After this, layer sequence optimisation is performed to eliminate collision between the robotic system and the part. If collision still exists, adjustments to the torch pose are made to avoid the remaining collision. The final chapter of this paper demonstrates the effectiveness of the proposed system via a real-world case study, where a workpiece with overhanging features was fabricated.

Geometric error sensitivity analysis for a 6-axis welding equipment based on Lie theory

The influence of geometric errors on the accuracy of machine tools tends to attract more attention to the increasing demand for high-precision machining. In this paper, geometric error modeling and sensitivity analysis are employed to quantify the importance of geometric error for a new efficient and automatic 6-axis welding equipment. The geometric error model of the 6-axis welding equipment with 36 geometric error components is established based on Lie theory. Based on the geometric error model, the new sensitivity analysis method, in which the deviation of the welding torch pose is treated as a distance metric in SE(3), is proposed to evaluate the influences of geometric errors on the accuracy of the welding torch. And the sensitivity coefficient of each geometric error is derived by considering the basic value of geometric errors. Numerical simulations of a typical welding trajectory for intersecting pipes are conducted to analyze the sensitivity of geometric errors by the new method. The simulation results verified the validity of the sensitivity analysis method and the dominant geometric errors affecting the accuracy of the welding equipment were identified. Compared with the previous sensitivity analysis method, the proposed sensitivity analysis method considers the orientation error and position error of the welding torch simultaneously, which is more convenient and effective, and can also be applied in precision design and geometric error compensation of machine tools.

Interpolation Algorithm and Mathematical Model in Automated Welding of Saddle-Shaped Weld

This paper presents welding torch pose model and interpolation algorithm of trajectory control of saddle-shaped weld formed by intersection of two pipes; the working principle, interpolation algorithm, welding experiment, and simulation result of the automatic welding system of the saddle-shaped weld are described. A variable angle interpolation method is used to control the trajectory and pose of the welding torch, which guarantees the constant linear terminal velocity. The mathematical model of the trajectory and pose of welding torch are established. Simulation and experiment have been carried out to verify the effectiveness of the proposed algorithm and mathematical model. The results demonstrate that the interpolation algorithm is well within the interpolation requirements of the saddle-shaped weld and ideal feed rate stability.

Research on Algorithm for Space Weld Reconstruction and Torch Pose Simulation

A path planning algorithm based on B-spline interpolation techniques was constructed for automatic welding system.The system used a B-spline curve to reconstruct the weld,it was achieved by reversing the control points of B-spline curve through the prescribed date points. The weld posture model was then obtained from the osculating plane and normal plane of B-spline curve. By taking a series coordinate transformation to the weld posture model, the torch posture model based on control terminal was provided.Experiments show that the new algorithm can readily be used for various three-dimensional welding tasks.

Kinematics Analysis and Torch Pose Fitting for Welding Robot

Giant structure processes involve highly dangerous manual welding operations. aiming at the welding for giant structures, tankers and other large work pieces, a five degrees of freedom (DOF) gantry type automatic welding robot was developed which has our own property right. Forward/inverse kinematics for the mechanical structure is analyzed in which pose of the welding torch is defined as a free vector. Then kinematics equations were proposed for torch pose fitting. Finally, simulation results for robot kinematics analysis and torch pose fitting were also proposed with Matlab. The result not only proves the feasibility of torch pose fitting, but also provides a basis for further study on kinematic analysis, torch pose fitting and off-line programming about gantry type automatic welding robot.