Jiyong Zhong

Research on the Real-time Tracking Information of Three-dimension Welding Seam in Robotic GTAW Process Based on Composite Sensor Technology

Aiming at the shortcomings of teaching-playback robot that can’t track the three-dimensional welding seam in real time during GTAW process, this paper designed a set of composite sensor system for tracking the three-dimensional welding seam based on visual sensor and arc sensor technology, which can effectively acquire three-dimensional welding seam information, such as clear images of seam and pool and stable arc voltage signals. The characteristic values of weld image and arc voltage signals were accurately extracted by using proper processing algorithm, and the experiments have been done to verify the precision of processing algorithms. The results demonstrate that the error is very small, which is accurate enough to meet the requirements of the subsequent real-time tracking and controlling during the welding robot GTAW process.

Real‐time image capturing and processing of seam and pool during robotic welding process

Purpose – The purpose of this paper is to analyze the technology of capturing and processing weld images in real‐time, which is very important to the seam tracking and the weld quality control during the robotic gas tungsten arc welding (GTAW) process.Design/methodology/approach – By analyzing some main parameters on the effect of image capturing, a passive vision sensor for welding robot was designed in order to capture clear and steady welding images. Based on the analysis of the characteristic of the welding images, a new improved Canny algorithm was proposed to detect the edges of seam and pool, and extract the seam and pool characteristic parameters. Finally, the image processing precision was verified by the random welding experiments.Findings – It was found that the seam and pool images can be clearly acquired by using the passive vision system, and the welding image characteristic parameters were accurately extracted through processing. The experiment results show that the precision range of the i...

Research on detection of welding penetration state during robotic GTAW process based on audible arc sound

– Penetration state is one of the most important factors for judging the quality of a gas tungsten arc welding (GTAW) joint. The purpose of this paper is to identify and classify the penetration state and welding quality through the features of arc sound signal during robotic GTAW process., – This paper tried to make a foundation work to achieve on‐line monitoring of penetration state to weld pool through arc sound signal. The statistic features of arc sound under different penetration states like partial penetration, full penetration and excessive penetration were extracted and analysed, and wavelet packet analysis was used to extract frequency energy at different frequency bands. The prediction models were established by artificial neural networks based on different features combination., – The experiment results demonstrated that each feature in time and frequency domain could react the penetration behaviour, arc sound in different frequency band had different performance at different penetration states and the prediction model established by 23 features in time domain and frequency domain got the best prediction effect to recognize different penetration states and welding quality through arc sound signal., – This paper tried to make a foundation work to achieve identifying penetration state and welding quality through the features of arc sound signal during robotic GTAW process. A total of 23 features in time domain and frequency domain were extracted at different penetration states. And energy at different frequency bands was proved to be an effective factor for identifying different penetration states. Finally, a prediction model built by 23 features was proved to have the best prediction effect of welding quality.

Automatic measuring and processing system of audio sensing for real-time arc height control of pulsed GTAW

Purpose – Surface forming control of welding bead is the fundamental study in automated welding. Considering that the vision sensing system cannot extract the height information of weld pool in pulsed GTAW process, so this paper designed a set of automatic measurement and control technology to achieve real-time arc height control via audio sensing system. The paper aims to discuss these issues. Design/methodology/approach – The experiment system is based on GTAW welding with acoustic sensor and signal conditioner. A combination denoising method was used to reduce the environmental noise and pulse interference noise. After extracting features of acoustic signal, the relationship between arc height and arc sound pressure was established by linear fitting. Then in order to improve the prediction accuracy of that model, the piecewise linear fitting method was proposed. Finally, arc height linear model of arc sound signal and arc height is divided into two parts and built in two different arc height conditions...

Research on Reconstruction of Weld Pool Surface Based on Shape from Shading During Robot Aluminum Alloy Pulse GTAW

In the interest of controlling the weld bead formation quality during robot aluminum alloy gas tungsten arc welding (GTAW) process, it’s necessary to monitor the shape and surface height information of the weld pool in real-time, which can indicate the penetration and formation. This paper presents an algorithm of shape from shading (SFS) based on single image for weld pool surface reconstruction. Two classic SFS algorithms are analyzed with the results of reconstruction from the synthetic half sphere image. Based on the Zheng and Chellapa algorithm, this paper proposes some measures for the improvement, such as smoothing process, strengthening the boundary constraints, using the known characteristics of the object surface and weighting error functions. And the improved algorithm is used to reconstruct the aluminum alloy weld pool surface during the robot pulse GTAW process. The result shows that the algorithm can successfully reconstruct the weld pool surface with effectiveness and accuracy and the computation of the surface height can be applied in real-time.

Research on the Robotic Arc Welding of a Five-Port Connector

The uncertain factors of welding process, such as the welding distortion, alternate edges in the welded seams and the variable quantity of the gap, would affect the weld appearance and quality directly. For the robotic arc welding of a five-port connector it’s necessary to establish a welding quality control system, which can realize seam tracking and welding formation control. The system captures the visual signals and the voltage signals to realize three-dimensional seam tracking. Furthermore, it stabilize the shape of the weld pool under the conditions of the varied gap and alternate edge.