Application case of machine vision inspection for high-speed rail pantograph slide

Background of the project:

At present, existing trains are basically driven by electricity, and the power comes from the power transmission grid, which is achieved by sliding contact between pantograph slides installed on the top of the train and the contact wires of the power grid. The current receiving quality of the contact system determines whether the train can obtain sufficient traction power and run safely and reliably. As the pantograph slide of the train is always in a high-speed motion state, any slight damage to the pantograph system, such as excessive wear of the pantograph slide, step-like wear, notches, and warpage not only affects the normal power supply of the train, the resulting arc Discharge will further exacerbate the abrasion of pantograph slides and catenary, and at the same time, it will also generate radio interference, which will cause pantograph failure, which will cause serious losses and impacts on the transportation and production of rail transit systems. Therefore, it is more important to prevent pantograph accidents.

High-speed rail pantograph skateboard

Project purpose:

Grasp the wear status and abnormal surface shape of pantograph slides, timely replace and adjust the components of the pantograph net, to detect, prevent and eliminate the pantograph malfunction early, and eliminate the accident in the bud state.

Project requirements and difficulties:

The test must be performed during normal train running, the detection area is not less than 2000mm * 1000mm, and the detection accuracy is required to be 0.5mm. Since the train does not stop and the movement speed is high, the results are only analyzed once the image is allowed to be collected, so the accuracy is guaranteed. In this way, multiple cameras can only be used for simultaneous acquisition, but this method requires high synchronization signals, and requires more software developers for multi-image stitching, and the complexity of the algorithm will directly reduce the detection efficiency;

solution:

According to the project requirements, the solution adopts a 29 million high-resolution industrial camera developed by Vision Image and sensors to collect data. The camera has a resolution of 6576 × 4384 pixels. During the high-speed operation of the train, only one frame of image is needed to complete the data collection. And, under the premise of ensuring 0.5mm accuracy, the shooting area can reach 3288mm × 2192mm. Since only a single image is processed through a software algorithm, the algorithm is simple and fast, and the train can receive the pantograph slide of the train during high-speed operation. The key characteristic parameters do not need manual inspection, complete large-area, high-precision inspection, avoid manual inspection of parking, safe, reliable and efficient.

Weishi 29 million pixel industrial camera

Hardware advantages:

MV-E2900M / C, this industrial camera has a resolution of up to 6576 * 4384 and a frame rate of up to 4 frames per second. The MV-E2900M / C industrial camera is divided into black and white and color (Bayer), using 35mm full-frame CCD image The sensor has a resolution of 6576x4384 pixels and a single pixel size of 5.5μmx5.5μm, which can effectively perform photoelectric conversion. Although the pixels are large and the pixels are large, the overall power consumption is controlled to 6w (@ 12V DC). The power consumption can reduce the noise caused by the heating of the sensor, thereby reducing the impact of noise on image quality. Therefore, this industrial camera has a higher signal-to-noise ratio (SNR) and better image quality. The global shutter is adopted in the shutter mode, which can avoid the deformation of the object caused by the different exposure start time of each line of the rolling shutter camera when capturing moving objects. It transmits via Gigabit Ethernet and supports flexible networking of multiple cameras. Gigabit Ethernet transmission enables a transmission distance of up to 100 meters, and it is convenient to continue to extend the transmission distance through optical fiber transmission equipment.

Vision high-resolution camera parameters

In addition, Visvision high-resolution cameras support the following functions:

1. Overlapping external trigger function, when the camera reads out the data after the exposure of the previous frame is completed, the camera can perform the exposure of the next frame, which improves the efficiency of image acquisition;

2. Built-in 128M frame buffer, when multi-camera synchronous acquisition, the image data in the frame buffer can be obtained through the function interface to prevent data loss due to insufficient bandwidth;

3. Supports automatic re-linking after the network is disconnected, and continues to transmit data, which avoids the situation of maintenance personnel going to the site to process and reduces system or equipment operation and maintenance costs.

This project has been entrusted to iJUNCO by CRRC Times.