Vibration table fatigue crack online detection system and detection method based on computer vision

Abstract

The invention discloses a vibration table fatigue crack online detection system based on computer vision. The system comprises image acquisition device,a support,a multipath data collector,a processor,a display and a crack detection module. Image / video information acquisition is carried out on an area where cracks are easily generated on the surface of the part by adjusting the position of the bracket by the image acquisition equipment; the multipath data collector gathers multipath data into one path of signal and transmits the signal to the processor; the crack detection module performs fatigue crack online detection through comparison frame extraction,vibration displacement elimination,feature screening,form screening,crack verification,crack actual length calculation,crack informationstatistics,auxiliary reminding,positive and negative sample accumulation and parameter self-adaptive adjustment,and outputs a crack information result through the display. Displacement generated by the vibration table can be eliminated in a self-adaptive mode,information such as the position,the length and the shape of a part crack can be obtained in a robust mode,and therefore automatic crack detection is achieved.

Description

technical field [0001] The invention relates to the field of video analysis and image processing, in particular to an on-line detection system and method for fatigue cracks of a vibrating table based on computer vision. Background technique [0002] The fatigue fracture results of metal parts are important indicators for evaluating the quality of metal parts. Accurate evaluation of the quality of metal parts can effectively reduce major safety accidents and economic losses caused by quality reasons during use. However, the existing traditional fatigue crack detection methods are mainly visual methods, which are difficult to read during the test, need to stop the measurement, have low measurement accuracy, and are easily affected by human factors. Moreover, if you want to achieve real-time online observation, you need to use More manpower is very time-consuming and labor-intensive. Therefore, how to accurately and reliably detect the initiation and growth of fatigue cracks o...

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Problems solved by technology

The ultrasonic infrared method uses the interaction between ultrasonic excitation energy and defects to generate temperature changes, and then collects temperature field information to detect crack information through a thermal imager, as proposed in the document "Application of Ultrasonic Infrared Thermal Imaging Technology in Metal Crack Detection" The disadvantage of this method is that it is difficult to obtain information such as the precise shape of the crack due to the propagation of heat, and it is difficult to achieve dynamic real-time detection; the eddy current method is based on the eddy current phenomenon of electromagnetics, and a high-frequency signal is applied to the tested specimen. When there is a defect on the surface, the eddy current density changes locally, and then the surface temperature distribution changes, and then the temperature field information is collected by the thermal imager to detect the crack information, such as the method proposed in the literature "Research on the Crack Detection Method of Metal Weld Seam with Eddy Current Inspired Thermal Imaging" , but in actual detection, the parameters such as electromagnetic properties and thermal properties of materials vary widely, eddy current detection is easily affected by the external magnetic field, and can only detect ferromagnetic materials, and the detection depth is only 2-3mm; the acoustic emission method uses the acoustic emission acquisition device , Microscopic image acquisition device and fatigue crack status real-time monitoring device, process the received signal, generate acoustic emission characteristic parameters, graphics and crack size data of the fatigue crack change process, and then realize online dynamic and real-time detection of fatigue crack initiation and growth, Such as the method proposed in the patent CN201310467034.7; the crack detection method based on computer vision detects crack information through design features, such as the method proposed in the invention patent CN201510916229.4, the existing method is only for static metal parts and can obtain good However, there is no suitable method and system for metal parts that vibrate rapidly on the vibration table in the fatigue fracture test

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