For this project, each ActiWheel system incorporates an optoNCDT 1420 laser triangulation sensor. “A critical part of the ActiWheel system is to understand the lateral position of the wheel relative to the rail. Then we can control the wheel and avoid the flange making contact with the rail head,” explains Cooney. “We’re really using the sensors to confirm that our complex controllers are actually working correctly.”
The optoNCDT 1420 laser triangulation sensor with integral controller is designed for high precision, high speed, dynamic displacement, distance and position measurement applications. The measuring rate is adjustable up to 4kHz. A range of different output signals enable easy integration of the sensor into plant or machine control systems. As well as analogue voltage and current outputs, a digital RS422 interface provides distance information from the sensor. All optoNCDT 1420 sensors operate using a web interface for fast sensor set up and configuration. Additional features of the optoNCDT 1420 include video signal display, signal peak selection and freely adjustable signal averaging, which enables optimisation of the measurement task. A region of interest (ROI) function allows background signal noise to be filtered out.
SET engineers built a special frame that lies beneath the wheel axle on the train. The optoNCDT 1420 sensors are mounted at a distance of 400mm from the rail head, just in front of the flange radius, pointing directly at the rail head. Measurement data from the sensors is output to the ActiWheel control system via 4-20mA.
Robust and reliable in harsh conditions
“We initially approached Micro-Epsilon for a suitable sensor and were very impressed with the application engineer who demonstrated the optoNCDT 1420 sensor to us. The sensor met all our technical requirements in terms of its flexibility, resolution and robustness. We are measuring down to 0.1mm accuracy and lateral movement can be up to a maximum of 20mm,” states Cooney.
“The sensors have performed very well in the demonstrator project and on other projects where we’ve tested the ActiWheel system. They are reliable even in the harsh environment underneath a train, where dust, dirt and moisture are present. They operate reliably whether it’s a cold, wet, rainy day or a bright sunny day. In the demonstrator project, we didn’t even have to clean the sensors after a couple of thousand miles of testing.”
“If we need to use the sensors for other applications, we can calibrate them ourselves and optimise their performance accordingly. We’ve also been impressed by the filtering function, which filters out noise from dirt, dust, grease and pieces of bent metal on the rail head, which means we can trust the measurement data.”
For more information on the optoNCDT 1420 laser triangulation sensors, please call the Micro-Epsilon sales department on +44 151 355 6070 or email email@example.com