Comparative tests of data acquisition equipment for use on high-speed trains undertaken by the Beijing Jiaotong University in China have demonstrated the effectiveness of HBM’s SoMat eDAQ equipment when operating under extremely tough conditions
The tests were undertaken to determine the best DAQ equipment for monitoring and analyzing fatigue and hence determining the potential failure of critical mechanical parts, such as the steering frame and connecting axis, on the recently developed 350 km/hr high-speed CHRIII train. The aim is to equip the new high-speed train with an eDAQ system during initial assembly so that data can be collected over the train’s operational lifetime for continuous condition monitoring. The specified equipment had to be capable of functioning properly under all weather and operational conditions.
The specifications called for the train under test to be equipped with two or three eDAQs with 32 channels per unit which would be used for a variety of inputs although the main uses were strain gauges, displacement and pressure monitoring.
The tests were conducted using equipment from six suppliers, including HBM. But HBM was not in a good position at the beginning as we were new to the customer compared with some of the other suppliers that had already supplied DAQ equipment.
However the test conditions were far harsher than in previous tests. Some of the specific challenges that the equipment faced included the placement of the sensors under the train where they would expect to operate over many days without checking. Ambient conditions included temperatures ranging from -20°C to 60°C with high levels of vibration, humidity and dust and electrical and magnetic interference.
HBM’s equipment was the only one that was able to function effectively during the two-day ultimate test.
The HBM equipment selected comprised the SoMat eDAQ combined with a SoMat eDAQ Vehicle Network Communications Layer (ECOM) and the SoMat eDAQ Bridge Layer (EBRG) to provide a comprehensive and robust integrated system.
HBM’s SoMat eDAQ is specifically designed as a rugged mobile data acquisition system. It features leading-edge signal conditioning and a capacity to perform a broad range of on-board data processing, triggering, intelligent data storage, and complex computations. It can be used as either a wired or wireless system as it utilizes Ethernet communications and hosts its own web server. It does not require PC software to start/stop tests or upload data.
The SoMat eDAQ Vehicle Network Communications Layer (ECOM) complements the eDAQ by providing three CAN device interfaces, a Vehicle Bus Module (VBM) interface and a GPS communications port. This makes the ECOM extremely versatile as it provides direct correlation between vehicle bus channels with physical data as well as GPS. Up to 254 vehicle bus channels can be recorded per input allowing total eDAQ system channel counts to be virtually limitless. Vehicle bus channels do not consume any analog inputs with all 254 channels input directly through a single connector.
Finally the SoMat eDAQ Bridge Layer (EBRG) provided 16 simultaneously-sampled low-level differential analog inputs through independent connectors. The EBRG works with both amplified and unamplified transducers including strain gauges, accelerometers, pressure transducers, load cells, and other general analog signals. The EBRG also provides excellent strain gage conditioning with support for 1/4, 1/2, and full-bridges.
Qian Xu, HBM’s Sales Engineer, says, “One of the key reasons we won the order was the eDAQ’s rugged ability to reliably record all data even under the harshest test conditions”.
Although these tests were conducted by the Beijing Jiaotong University the trains are operated by China CNR Corporation Limited. CNR’s business includes the design, manufacture, refurbishment, overhaul and maintenance of electric locomotives, diesel locomotives, passenger coaches and freight wagons, electric and diesel multiple units, traction motors and rolling stock. CNR provides more than half of 500,000 locomotives and rolling stock on over 70,000 kilometer of the Chinese railway.