With the continuous advancement of technology, the detection and monitoring equipment for rail transit is accelerating its transition from traditional manual operation to a new stage of intelligence and automation. Its functions are becoming increasingly rich. Automatic fault diagnosis, trend analysis, alarm handling, etc. have become standard features, significantly enhancing the real-time performance and accuracy of detection. Meanwhile, the extensive application of technologies such as inspection robots and unmanned transformation has significantly reduced human intervention, effectively enhancing the efficiency and safety of rail transit operation and maintenance. Many companies, such as YoseenIR, have accumulated project experience in key application areas of rail transit, including train pantograph monitoring, axle temperature monitoring, and train inspection thermal imaging. This has promoted the development of rail transit detection equipment towards intelligence, enhanced the coordination and efficiency of detection work, and provided technical support for the integrated operation and maintenance of the entire rail transit system.

High-speed infrared thermal cameras are thermal imaging devices capable of capturing and processing infrared images at extremely fast frame rates. They are particularly suitable for temperature monitoring and analysis in scenarios that require rapid response and high dynamic range. The temperature monitoring of train axles is crucial for ensuring the safety of railway operations, especially when trains are running at high speeds. Axles and their components (such as journal shafts, bearing shells, and bearings) are subjected to extreme mechanical stress and frictional heat, and their temperature conditions directly affect the reliability of train operation and the safety of passengers and goods. YoseenIR has launched a new uncooled high-speed infrared thermal camera, specially developed for the rail transit industry. It is used for real-time and precise monitoring of the operating temperature of high-speed rotating train axles and components, as well as thermal imaging monitoring and analysis in scientific research scenarios that require high-speed capture of minute temperature differences.

The YoseenIR high-speed infrared thermal camera is equipped with high-quality and high-performance detectors, featuring stable performance and rapid and sensitive response to fast-moving objects. With a thermal time constant of 4ms, it can quickly capture subtle temperature changes, which is approximately three times the thermal energy capture capacity of conventional thermal cameras. With a high frame rate of 125Hz, it accurately captures every frame of temperature data, ensuring smooth and lag-free images.

Image effects of YoseenIR thermal cameras under different configurations

Thermal camera frame rate: It refers to the number of images that a thermal camera can capture, process and display within one second, with the unit being Hz (Hertz). In simple terms, the higher the frame rate, the better the thermal camera performs in capturing and detecting moving targets or lens movements. For instance, when shooting fast-moving trains, cars, or running animals, the resulting images have less trailing and the real-time video quality is smoother. The higher the frame rate of an infrared thermal camera, the better the dynamic observation effect. In addition, the thermal time constant is also very crucial.

The thermal time constant of a thermal camera is a concept of time, which is used to measure the time required to respond to temperature changes. Of course, the shorter this time, the better.

Infrared thermal image of pantograph net under high-speed operation

Thermal time constant: The time constant of a conventional uncooled thermal camera is 8-12ms, but this does not mean that an accurate result can be read every 8-12ms. It usually takes five time constants to reach a stable state to obtain an accurate temperature information. The following figure shows the system response from 0°C to 100°C, with tau=14ms and half the time =8ms-12ms (the stabilization time required to immediately align the detector with a black body at 100°C after aligning it with ice water at 0°C).

System response from 0°C to 100°C

When a train is in operation, the load-bearing bearings will generate heat due to friction. When a fault occurs inside the bearing, the friction will intensify and the temperature will rise sharply. When it reaches a certain level, it will form a hot axle, and in severe cases, it may lead to faults such as axle cutting. Therefore, it is necessary to monitor and warn of the temperature of the wheel axle and other parts in real time to improve the safety and reliability of railway equipment. At the site of the train axle thermal imaging temperature monitoring project, based on the on-site investigation by the staff of YoseenIR, it was decided to set up YoseenIR high-speed infrared thermal cameras at key positions along the railway line to automatically scan the axles of passing trains, which are used to detect axle boxes, bearings, etc. of the axles to prevent faults caused by high-temperature deformation. The high-speed infrared thermal camera and its supporting software system can transmit data in real time to the central monitoring center, achieving large-scale, all-weather remote monitoring, improving the efficiency of fault detection, and reducing the cost of manual inspection.

Installation location of YoseenIR thermal imaging equipment

The main advantages of the YoseenIR high-speed infrared thermal camera for axle temperature monitoring are as follows:

125Hz ultra-high frame rate thermal camera, with sensitive and precise response

A 125Hz high-speed thermal camera with a 4ms thermal time constant is selected to respond quickly to high-speed moving axles, providing high-definition images without delay or trailing.

Real-time and uninterrupted monitoring, quickly capturing the temperature of each frame

When the train passes at high speed, the temperature distribution images of the axles and their components are quickly captured. Each frame of the temperature picture is rapidly captured to achieve real-time precise monitoring of the thermal state and over-temperature early warning.

Data analysis and trend prediction enhance maintenance efficiency

Real-time temperature data collection and storage, intelligent analysis of the temperature change trend of the axle, provide a scientific basis for the preventive diagnosis and maintenance of each component of the axle.

The software interface for high-speed thermal cameras

In addition, as an advanced non-contact temperature measurement tool, high-speed thermal cameras can capture the temperature changes on the surface of objects in an extremely short time, providing strong support for scientific research in multiple fields. The feature of high frame rate enables it to monitor rapidly changing thermal phenomena in real time and continuously, which is of great significance for dynamic research and the analysis of high-speed processes. High precision ensures the reliability and accuracy of measurement results, reduces errors, and provides a solid data foundation for scientific research. Especially in complex dynamic processes such as fluid mechanics, material research, welding experiments and collision experiments, the application of high-speed thermal cameras has demonstrated its unique advantages.