Trajectory Control Of Spatial Intersected Curves In Automated Welding

Welding plays a prime important role in many industries, including military industry. Now China's welding industry has become the top one in the world, but it is still at a low automation level because of its late startup. There is still a large gap in the automated welding equipments between China and the main developed countries, such as Britain, the United States, Germany, France, Italy and Japan.The welding of Spatial Intersected Curves (SIC) is a common task in many industries. The automated welding of SIC has been drawing great attention from universities and research institutes because of its great importance in industries. The welding of SIC exists in many industries, such as car manufacturing, shipbuilding, oil transportation pressure vessels and water supply, etc. China has imported many automated equipments from USA, Germany, Austria for SIC welding, but we hasn't mastered the core technology for automated SIC welding. There is the urgent need to research the key technology and to develop automated SIC welding equipment with our own independent intellectual property.The accurate description for welding seam is the fist step in automated welding, and it has an important effect on welding precision. This thesis first analyzes the limitation of the way of welding seam description through space geometric analysis, and then proposes a new method - welding seam fitting by B-spline curve algorithm, with which the mathematical parameterized expression of the seam will be acquired. Also the thesis analyzes the accuracy of the B-spline algorithm fitting method by MATLAB.The interpolation algorithm is the core technology of Numerical Control (NC) system, and high-speed and high-precision are always the targets for interpolation algorithm research. The thesis researches the B-spline interpolation algorithm for automated welding of SIC. Based on the analysis of traditional algorithms, a universal interpolation algorithm with high speed and high precision is proposed, which can be used for the motion control both in Cartesian coordinates and non-Cartesian coordinates systems. The B-spline interpolation algorithm for SIC welding is proved in the thesis with MATLAB.The automated welding control system is introduced in the thesis, including the hardware design and software programming. The hardware system adopts the Industrial Personal Computer (IPC) as the control platform, and the system structure has the opening, modular and embeddable characteristics. To improve the program execution efficiency and decrease the memory requirement, the complexity of the algorithms is fully considered to attain algorithm's high-speed and high-efficiency. The program is written modularly with Visual C++.