Research Of High-speed Image Acquisition For Wheel-set Wear Measurement

Wheel-set is an important part of the vehicle. The wear condition of the wheel-set has an important influence on the vehicle’s driving safely. With the continuous development of the China’s railway transportation, vehicle speed and carrying capacity were greatly improved, and the wheel-set wear also became more serious. The wheel-set wear had threat the safe driving. In our country, the measurement system used in the wheel-set wear detection can work well while the speed is less than15km/h. In order to meet the needs of China’s high-speed railway detection, the paper proposed a high-speed image acquisition system. A high-speed image acquisition system based on machine vision had been designed, and the system worked in the asynchronous reset mode, and it has flash synchronization function. When the wheel-set went through the detection area, the system could get a clear image. The main content of the research in this article:(1) A high-speed image acquisition method was proposed, in this method the system has flash synchronization function.(2) An online high-speed image acquisition system, which was based on the machine vision and worked in the asynchronous reset mode, was designed. Firstly, the optical system had been analyzed, the light source had been designed, the installation position of the camera and the light source had been discussed. Secondly, the trigger module had been designed. Thirdly, a high accurate time sequence adjustment device had been designed. The exposure time sequence and flash sequence could be controlled, and guarantee the system get a clear image while the wheel-set arrived at the preset position. Finally, through choosing the right camera and frame grabber the asynchronous reset acquisition had been realized.(3) According to the project requirement, the system software had been designed. The image acquisition software and the delay time control software had been finished with VC++6.0. In the image acquisition software, the hardware trigger, software trigger, surveillance, and single-frame capture had been realized, and it could meet the need of the project. The exposure time sequence and flash sequence could be controlled by using the delay time control software.In the system the camera and the flash could work at a frequency of380Hz, the synchronization error of the exposure time sequence and the flash time sequence was less than25μs, and the system could got a clear image while the speed was less than 80km/h and the exposure time is45μs. All of these had been verified by the experiments.