Developing a Compact Data Logger for Railroad and Rail Vehicle Performance Validation

Author(s):

Arunkumar Manoharan - Apna Technologies & Solutions Private Limited
Sriram Iyer - Apna Technologies and Solutions Pvt Ltd
Starlin Immanuel - Apna Technologies and Solutions Pvt Ltd
Senthil R. Desappan - Apna Technologies and Solutions Pvt Ltd

The Research Design and Standards Organisation of the Ministry of Railways of India uses validation trials to set standards for Indian railway conditions. During validation trials, we test trains with certain load and speed criteria on a new or existing railway line. We also test locomotives and railway vehicles with modified designs under different track conditions.

Knowing parameters such as twist, gauge, alignment, and unevenness is critical for trains to run in a track. We needed to create a product to digitize, store, and analyze data in a running train with flexibility in sensor connection and appropriate signal conditioners. We needed the logger to withstand the high vibration and electromagnetic interference common in the railroad environment.

We used CompactRIO and LabVIEW to create the Apna Versatile Data Acquisition System (apnaVDAS) data logger. Various CompactRIO modules gave us the plug-and-play configuration we required for the system. We developed a LabVIEW application to detect the configuration of the modules and load the appropriate user interface and analysis. Some types of sensors we integrated include strain, accelerometer, displacement, pressure, temperature, and speed. The application creates a live track chart with measurements from sensors and marks corresponding to events (locations such as curves, straight lines, bridges, rise, fall, and stations) recorded by the imaging sensor and corresponding manual entries. Online and offline analysis software analyzes the recorded information. The apnaVDAS data logger has a modular front panel and built-in signal conditioning modules. The front panel provides signal-specific LEMO connectors for ease of handling and can withstand measurement conditions in a running train.

Railway Trials

The apnaVDAS performs the following railway trials:

• Track Monitoring Run: An ideal-condition locomotive runs on a track under test. We mount accelerometers on different locations in the locomotive to monitor the lateral and vertical acceleration, and the resulting acceleration value must fall under the allowable limit.
• Oscillation Trial: The track is in ideal condition, and we instrument the vehicle under test to measure lateral acceleration, vertical acceleration, longitudinal acceleration, bogie suspension (with and without load), and tilt performance.
• Jerk Trial: The track is in ideal condition, and we instrument the vehicle under test to measure different accelerations. The locomotive suddenly stops and we measure longitudinal (traveling direction), vertical, and lateral acceleration. We use these parameters to measure the riding index of the vehicle. The quality riding index helps us analyze the skill of the locomotive pilot, and the comfort riding index helps us analyze the comfort of the commuters.
• Confirmatory Oscillation Car Run Trial: The track is in ideal condition, and an oscillograph car (an instrumented railway coach) measures lateral and vertical acceleration.
• Emergency Brake Distance Trial: The test train runs at the maximum permissible speed and the operator applies the emergency brake. We continuously monitor the speed from an instrumented axle in the test vehicle. After application of the emergency brake, we measure the stopping distance of the vehicle.
• Adhesion Trial: We use this trial to calculate the maximum pulling force of the locomotive. The locomotive under test is coupled with two or three locomotives under brake-applied conditions. The test locomotive pulls the locomotive under the brake-applied condition. We perform the test in stationary and dynamic conditions where the pilot can change the notch from level 1 to level 7. We measure and analyze each level of strain formed in the coupler to calculate the pulling of the locomotive.
• Coupler Force Trial: We selected maximum pulling and pushing force of the region for this trial. In the hill region, track conditions are 37:1 (for every 37-meter length of track, one meter level changes). The locomotive runs 15 km/h in rise-and-fall track conditions. The push and pull force is derived from the strain formed in the coupler between the locomotives.

For each trial, we map the data with the video acquired by the imaging sensor. We also mark events along the data recording with the help of assigned function keys.

Measurement Architecture

We connected sensors mounted on different measurement points in the oscillograph car or test vehicle to the apnaVDAS with a shielded cable. The other end of the shielded cable features LEMO connectors. The connector size and mating notches are different for different signal types to avoid problems in the field.

After we configure the test and initialize the CompactRIO controller, the NI cRIO-9014 controller collects the data from other CompactRIO modules at 100 S/s and transfers the data to a rugged laptop.

Data Logger

We used an 8-slot NI CompactRIO chassis that we can configure to meet any test requirement. LEMO connectors interface from the field sensor to the enclosure front panels. The connectors feed required excitation voltage and current via sensors through customized module printed circuit boards. The data logger features battery backup for up to four hours in case of an emergency. The enclosure complies with the IP65 rating and is rugged enough to work in train-running conditions.

Software

We used LabVIEW to develop the apnaVDS software. Customers can configure the display and sensor scaling parameters in the apnaVDAS software per test requirements. They can save and retrieve data for similar trials.

Conclusion

We used LabVIEW and CompactRIO to develop a reliable, rugged data logger with field-configurable plug-and-play I/O modules to meet stringent requirements. We successfully conducted several railway trials. LabVIEW and CompactRIO reduced development time and increased the reliability of our system, as we needed fewer components to complete the logger.

Author Information:

Arunkumar Manoharan
Apna Technologies & Solutions Private Limited
No:1, Coconut Garden Cross,Outer Ring Road,Kalyan Nagar Post
Bangalore 560043
India
Tel: 080-25426463
arunkumar.manoharan@gmail.com