A pulse gtaw welding process control method based on iterative learning
A welding process and iterative learning technology, applied in welding equipment, manufacturing tools, arc welding equipment, etc., can solve the problems of reducing the welding quality of workpieces, difficulty in obtaining effective control models, and time-varying uncertainties with large lags. simple effect
Active Publication Date: 2018-07-24
HENAN POLYTECHNIC UNIV
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Problems solved by technology
The difficulty lies in: First, due to the complex mechanism of the welding process, which presents the characteristics of high nonlinearity, large lag and time-varying uncertainty, it is difficult to establish an accurate model of the welding system, so it is difficult to obtain an effective control model using the model-based control method
Secondly, due to the extremely changeable welding environment and the existence of noise interference and load disturbance, the parameters and even the structure of the welding system will change with time, which makes the parameter setting of the classic PID control algorithm difficult.
In addition, currently used intelligent control methods such as model-free adaptive control
Although it does not depend on the precise model of the welding system, it can suppress the uncertain interference of the external environment, but this method needs a certain transition time to achieve the desired index
Then the weld seam formed in the early transition stage will reduce the welding quality of the workpiece as a whole
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[0021] The present invention will be further described below in conjunction with the accompanying drawings.
[0022] Such as figure 1 As shown, the operating principle diagram of the pulsed GTAW welding control system based on PD-type iterative learning law.
[0023] (a) Without loss of generality, assuming that the Kth welding is being performed, the control quantity memory provides the welding peak current u at each moment in the current operation k (t); during the welding process, the arc acts on the workpiece to generate a weld, and the back fusion width y of the weld is indirectly measured by the visual sensor k (t), and then calculate the back fusion width error e k (t), and stored in the error memory;
[0024] (b) When the Kth welding process ends, the controller uses the data in the error storage including e k (t), e k (t+1) and the control input u in the control variable memory k (t) Calculate the peak current of the K+1th welding, and save it to the control qua...
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The invention provides a pulse GTAW welding process control method based on iterative learning. The method includes the following steps that 1, the welding control process is initialized; 2, k welding operation is started, wherein a visual sensor measures the back weld width ky(t) of a weld joint, then the back weld width ky(t) is compared with an expected value yd(t) in a memorizer, and the back weld width error ek(t) is obtained; 3, the control amount memorizer is updated, wherein after the k welding operation is completed, if the back weld width meets the condition shown in the specification, (k+1) welding operation is directly carried out; or else, welding peak current of the (k+1) welding operation is obtained according to a PD type interactive control law; 4, 1 is automatically added to the k value, and the step 2 is shifted to sequentially complete following welding control tasks. The characteristic of welding process repeatability is fully utilized, and the back weld width of the weld joint can rapidly reach and even completely reach expected indexes through a PD type iterative learning control algorithm. A controller is simple in structure, and certain inhibiting capacity is achieved for non-repetitive disturbance in the welding process.
Description
technical field [0001] The invention relates to the technical field of arc welding process control, in particular to a pulse GTAW welding process control method based on iterative learning. Background technique [0002] Pulse GTAW welding refers to the method of welding under the protection of inert gas, using a pulsed AC power supply through the arc between the tungsten electrode welding head and the workpiece. The arc welding process involves complex interactions of physics, chemistry, materials, metallurgy and many other aspects. It can be seen from the welding process requirements that complete penetration is an important prerequisite for forming a strong and reliable weld. Therefore, in order to achieve high-efficiency automatic welding, the control of weld penetration has always been the focus of welding control technology research. The difficulty lies in: First, due to the complex mechanism of the welding process, which presents the characteristics of high nonlinear...
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IPC IPC(8): B23K9/167B23K9/095B23K9/09
CPCB23K9/09B23K9/0956B23K9/167
Inventor 卜旭辉尹艳玲崔立志杨俊起梁嘉琪
Owner HENAN POLYTECHNIC UNIV