laser sensors

Targeting accuracy and precision with laser sensors

Bestech is providing the local rail industry with access to products such as laser sensors that are used in driving advanced solutions.

The fundamentals of rail wheel interaction have been established for many decades. The conical shape of the wheels allows for the wheel set to shift while rounding a curve, and for the train to stay on track. These engineering principles have served railways well for centuries, however engineers are now looking for a way to reduce rail wear, allowing the tracks to operate longer without maintenance.

In a trial underway in the UK, an array of optoNCDT 1420 compact laser triangulation sensors from Micro-Epsilon have been installed to provide the measurement behind the ActiWheel solution. The sensors guide the ActiWheel traction system to produce more driving force on one side of the wheelset to ensure the train travels down the centreline of the track. The solution would overcome the compromises and issues that result from the combination of a solid axle and wheel coning and reduce wear on the wheel and the rail.

ActiWheel relies upon precise and accurate measurements from the optoNCDT sensors to provide the information for the artificial intelligence software that drives the motors that are individually affixed to each wheel. The optoNCDT sensors measure the lateral position of the wheel, relative to the rail, and according to Neil Cooney, technical director at the UK company behind ActiWheel, SET, the particular specifications of the sensor made it the perfect fit.

“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,” said Cooney.

This is not the only application of laser sensors in the rail industry. Sensors such as the optoNCDT have been widely used for maintenance of rail tracks and to measure wear and tear. This is in addition to track guiding devices that are installed below the train, which also use laser sensors. The conditions within these applications require a certain kind of sensor.

“These require a compact sensor that can be easily installed and provide accurate and reliable measurement at high speed,” said Wirhan Prationo, marketing engineer at Bestech, which distribute sensors from Micro-Epsilon in Australia.

As seen in its adoption for the innovative ActiWheel solution, the compact optoNCDT is optimised for the rail industry as a laser triangulation sensor.

“It combines speed, size, performance and versatility for measurement applications in the rail industry. This compact laser triangulation sensor is suitable for measuring distance and displacement up to 500mm with maximum sampling speed of 4kHz. It also can be easily integrated in restricted and narrow installation space,” said Prationo.

In the ActiWheel case, the sensor was particularly useful when it came to ensuring that the data collected was only that which was required, said Cooney.

“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,” said Cooney.

To use the sensors, SET created a frame that lies beneath the wheel axle of the train, 400mm from the rail head. The sensors are located in front of the flange and point towards the rail head. The data from this assembly is then transferred to the ActiWheel control system via a 4-20mA analogue signal. Operation and configuration can be done using the web- based interface. While these are the settings used by the ActiWheel team there are other information channels available.

“The optoNCDT laser triangulation sensor offers a range of different output signals that enable easy integration of the sensor into any industrial control system,” said Prationo. “The sensors are operated through the web interface and they also have additional analysis features, such as video signal display, signal peak selection, background noise filtering and signal averaging. A mobile data acquisition unit can be used to collect the data, which can be connected to the computer on board.”

With the trial ongoing in the UK, the optoNCDT’s technical specifications have been tested in a variety of environments. Rated to an IP65 protection level, the system is housed within a casing that is impenetrable by dirt and dust.

During the demonstration, the optoNCDT sensors were able to read accurate data in the harsh environment underneath the train, where dust, dirt, and moisture are present. They also delivered consistent reading irrespective of whether it’s a cold, wet, rainy or bright sunny day. After running for a couple of thousand miles the sensors did not need cleaning.

While the further development of ActiWheel promises much for reducing rolling contact fatigue, this is only one potential application of the optoNCDT sensors.

Located in Australia, Bestech is able to collaborate with rail organisations seeking to leverage the precision and accuracy of laser sensor technology.

“Bestech have more than 40 years of experiences in sensors and instrumentation for solving test and measurement challenges in the industry,” said Prationo. “We offer not only high-quality products, but also our technical expertise and support to assist with real-time application to correctly gather the data you require. Bestech can also customise the product to fit into certain requirements, such as different cable length, integration with mobile data acquisition system or signal conditioning to fit into the existing devices.”

“Our team is supported by highly- trained applications engineers and product specialists with a wealth of experience in sensor applications for measurement of physical parameters in the industry.”

Precise measurement for effective rail track maintenance

Overcoming the limitations of manual inspection of rail track wear is simplified with Bestech’s laser profile scanner.

The number of train travellers on major metropolitan railways are growing with annual increase of 3 per cent in Sydney, and almost 10 per cent in Melbourne since 2010, according to Infrastructure Australia and the Australian Bureau of Infrastructure Transport and Regional Economics (BITRE). The effective maintenance of rail and track is one way that operators and infrastructure managers can safely increase capacity on their networks, as the Victorian government’s submission to the Select Committee on Train Services outlined.

In New South Wales, passenger trips have surpassed the numbers predicted for 2030, with train patronage having already increased by 30 per cent when compared to those in 2011, based on NSW government figures. Meanwhile in Melbourne, Metro Trains Melbourne has added 10,000 more train services in the last 10 years to meet patronage levels of 229.6 million passenger travels in 2019.

These extra services put extra loads and stresses on the existing rail infrastructure which wear them faster. Some of these services are also run on ageing tracks and legacy networks, meaning maintenance has to keep up with the increasing demand, to avoid disruptions or potentially fatal accidents. Traditional maintenance techniques for rail tracks rely on manual inspection to visually detect the wear.

As maintenance managers are looking to improve efficiency on their regular maintenance schedules, this traditional inspection method is no longer feasible or reliable enough.

To meet these challenges, there is a need for a device or system that is able to accurately profile rail tracks and automatically determine their wear and tear. One way that this can be achieved is to use laser profile scanners.

As a leading sensors and instrumentation company in Oceania, Bestech Australia supply design and manufacture sensors for measurement of physical parameters. Bestech has been supplying the Australian rail industry with the scanCONTROL laser profile scanner from Micro-Epsilon for rail monitoring applications.

“The scanControl has been previously used for measuring the wear and tear of the rail head,” said Bestech marketing engineer, Wirhan Prationo. “If the wear is too high, engineers can be notified so essential maintenance should be scheduled. Leaving the track as is could potentially derail the trains running on it, which can be fatal.”

Instead of manual inspections, which can be costly and inaccurate due to their reliance on human operators, scanControl can automatically determine wear and tear on the rail head at high speed. A minimum of two scanCONTROL scanners are required to measure the entire rail head profile. Mounted onto a measurement wagon, an array of four synchronously operated sensors can record profile data at speeds of up to 100km/h. The collected data is continuously compared with target profile in the evaluation software.

The deviation from a defined tolerance limit is marked on the map, allowing the maintenance operator to precisely locate the location to conduct repair.

“The laser profile scanner from MicroEpsilon is considered one of the highest performing laser profile scanners in its class due to their high accuracy and measuring rate. The sensor head is also equipped with intelligence for solving various measurement tasks such as profile, width, depth, edge, groove, gap, angle, flatness, deformations, and many other properties. It can also be individually programmed by integrators for custom requirement. All scanCONTROL sensors are equipped with Real-Time- Surface-Compensation feature for reliable measurement under rapidly changing conditions. More importantly, the sensors also come with GPS synchronisation which allow mapping of the entire railway tracks and fast identification of the problematic location,” said Prationo.

The non-contact profile measurement using laser scanners provides an
innovative, time saving solution for rail wear identification as compared with the conventional visual inspection technique. Customers can manually specify permissible deviation through the user-friendly interface. The data can be transferred to the cloud software application to create a detailed, interactive map of the entire rail network.

The scanCONTROL profile scanners offer a high precision and resolution scan which allows for up-to-date maintenance programs to be carried out, and directed to those sections of a track which require them most. The laser scanners can record data at a maximum speed of 10kHz at a resolution of 1,280 points/profile in the x-axis and 1μm in the z-axis.

The laser scanners are also designed to withstand harsh conditions and tested to reliably operate within a temperature range of -20 to 70°C and in strong sunlight. They are also able to withstand vibrations from the wagon or when used in an industrial environment.

Furthermore, the system has been designed with the user in mind, being compatible with image processing tools, said Prationo.

“Each scanControl scanner complies with the GigE vision standard of the Australian Imaging Association (AIA) which is widely used in image processing and supported by all conventional vision tools. This standard is essential to ensure fast and smooth integration with different image processing software for 3D profile evaluation.”

In addition to applications in the heavy rail sector, scanControl scanners have been used by light rail track maintenance providers. Mounted to a measurement wagon, two scanControl units produced a profile measurement of tram rails. The laser scanners can be integrated into the measurement system using a free SDK.

“The scanners are used to map a cross- section profile of the rail. The measured data can be compared with the stored reference data to automatically recognise wear,” said Prationo.

The data profile can be transmitted to the cloud software applications for a detailed, interactive map of the rail network, where the respective condition of the single section of the rail can be highlighted and reviewed.

In the manufacturing of railway sleepers, the scanCONTROL laser scanners can also be used as part of quality control. The process requires a high-speed, high-precision system with robust design, which the scanCONTROL scanners offer.

The implementation of advanced sensor technology such as the scanCONTROL
has proven to deliver effectiveness and efficiency in the rail industry.

“As a leading company in sensors and instrumentation in Australia and New Zealand, Bestech Australia offers not only the product, but also technical support and complete turn-key solutions for test and measurement requirements in the industry. We have more than 15 application engineers with various background to support you in understanding your applications and offer tailored solutions for your measuring requirements,” said Prationo.

Measuring lateral position of rail bogie relative to the tracks

It is crucial to ensure that the health of the tracks are regularly monitored as the train can potentially derail if the tracks are damaged.

The laser profile scanners are ideal to scan the wear and tear on the rail tracks and have been previously used for this type of measurement applications.